The Inoculum Effect in the Era of Multidrug Resistance: Minor Differences in Inoculum Have Dramatic Effect on Minimal Inhibitory Concentration Determination.

PubMed

Smith, Kenneth P; Kirby, James E

2018-05-21

The observed MIC may depend on the number of bacteria initially inoculated into the assay. This phenomenon is termed the inoculum effect (IE) and is often most pronounced for β-lactams in strains expressing β-lactamase enzymes. The Clinical and Laboratory Standards Institute (CLSI) recommended inoculum is 5 x 10 5 CFU mL -1 with an acceptable range of 2-8 x 10 5 CFU mL -1 IE testing is typically performed using an inoculum 100-fold greater than the CLSI recommended inoculum. Therefore, it remains unknown whether the IE influences MICs during testing performed according to CLSI guidelines. Here, we utilized inkjet printing technology to test the IE on cefepime, meropenem, and ceftazidime-avibactam. First, we determined that inkjet dispense volume correlated well with the number of bacteria delivered to microwells in two-fold (R 2 = 0.99) or 1.1-fold (R 2 = 0.98) serial dilutions. We then quantified the IE by dispensing orthogonal titrations of bacterial cells and antibiotics. For cefepime resistant and susceptible dose-dependent strains, a 2-fold increase in inoculum resulted in a 1.6 Log 2 -fold increase in MIC. For carbapenemase-producing strains, each 2-fold reduction in inoculum resulted in a 1.26 Log 2 -fold reduction in meropenem MIC. At the lower end of the CLSI allowable inoculum range, minor error rates of 34.8% were observed for meropenem when testing a resistant strain set. Ceftazidime-avibactam was not subject to an appreciable IE. Our results suggest that IE is sufficiently pronounced for meropenem and cefepime in multidrug-resistant Gram-negative pathogens to affect categorical interpretations during standard laboratory testing. Copyright © 2018 American Society for Microbiology.

Mixed arbuscular mycorrhizal (AM) fungal application to improve growth and arsenic accumulation of Pteris vittata (As hyperaccumulator) grown in As-contaminated soil.

PubMed

Leung, H M; Leung, A O W; Ye, Z H; Cheung, K C; Yung, K K L

2013-08-01

A greenhouse pot experiment was conducted to study the effects of three types of single inoculum [indigenous mycorrhizas (IM) isolated from As mine, Glomus mosseae (GM) and Glomus intraradices (GI)] and two types of mixed inoculum (mixed with IM and either GM or GI) on the growth response of Pteris vittata (hyperaccumulator) and Cynodon dactylon (non-hyperaccumulator) at three levels of As concentrations (0, 100 and 200mgkg(-1)). Both mycorrhizal plants exhibited significantly higher biomass, and N and P accumulation in its tissue than the control. Among the mycorrhizal inoculum, the mixed inoculum IM/GM promoted substantially higher mycorrhizal colonization and arsenate reductase activity in P. vittata than C. dactylon, among all As levels. The portion of Paris arbuscular mycorrhizal structure (observed in colonized roots) together with the highest As translocation factor of 10.2 in P. vittata inoculated with IM/GM was also noted. It was deduced that IM/GM inoculum may be the best choice for field inoculation at any contaminated lands as the inoculum exhibited better adaptation to variable environmental conditions and hence benefited the host plants. Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.

Incubation of Phytophthora ramorum-infested leaf debris in soil affects survival, sporulation capacity, and subsequent risk of epidemic development within nurseries

Treesearch

Ebba K. Peterson; Niklaus J. Grünwald; Jennifer L. Parke

2017-01-01

Soilborne inoculum (infested leaf debris which has become incorporated into the soil) may be an important contributor to the persistence of the sudden oak death pathogen Phytophthora ramorum in recurrently positive nurseries. To initiate new epidemics, soilborne inoculum must not only be able to survive over time, but also be capable of producing...

Growth and enterotoxin production of Staphylococcus aureus during the manufacture and ripening of Camembert-type cheeses from raw goats' milk.

PubMed

Meyrand, A; Boutrand-Loei, S; Ray-Gueniot, S; Mazuy, C; Gaspard, C E; Jaubert, G; Perrin, G; Lapeyre, C; Vernozy-Rozand, C

1998-09-01

Tests were carried out to determine the effect of manufacturing procedures for a Camembert-type cheese from raw goats' milk on the growth and survival of Staphylococcus aureus organisms added to milk at the start of the process, and to study the possible presence of staphylococcal enterotoxin A in these cheeses. The initial staphylococcal counts were, respectively, 2, 3, 4, 5 and 6 log cfu ml-1. Cheese was prepared following the industrial specifications and ripened for 41 d. Detection of enterotoxins was done by the Vidas SET test and by an indirect double-sandwich ELISA technique using antienterotoxin monoclonal antibodies. Generally, numbers of microbes increased at a similar rate during manufacture in all cheeses until salting. During the ripening period, the aerobic plate count population and Staph. aureus levels remained stable and high. There was an approximately 1 log reduction of Staph. aureus in cheeses made with an initial inoculum of Staph. aureus greater than 10(3) cfu ml-1 at the end of the ripening period (41 d) compared with the count at 22 h. The level of staphylococcal enterotoxin A recovered varied from 1 to 3.2 ng g-1 of cheese made with an initial population of 10(3)-10(6) cfu ml-1. No trace of enterotoxin A was detected in cheeses made with the lowest Staph. aureus inoculum used in this study.

Impact of accessory gene regulator (agr) dysfunction on vancomycin pharmacodynamics among Canadian community and health-care associated methicillin-resistant Staphylococcus aureus

PubMed Central

2011-01-01

Background The accessory gene regulator (agr) is a quorum sensing cluster of genes which control colonization and virulence in Staphylococcus aureus. We evaluated agr function in community- (CA) and healthcare-associated (HA) MRSA, to compare the pharmacodynamics and bactericidal activity of vancomycin against agr functional and dysfunctional HA-MRSA and CA-MRSA. Methods 40 clinical isolates of MRSA from the Canadian Nosocomial Infection Surveillance Program were evaluated for delta-haemolysin production, as a surrogate marker of agr function. Time kill experiments were performed for vancomycin at 0 to 64 times the MIC against an initial inoculum of 106 and 108 cfu/ml of agr functional and dysfunctional CA-MRSA and HA-MRSA and these data were fit to a hill-type pharmacodynamic model. Results 15% isolates were agr dysfunctional, which was higher among HA-MRSA (26.3%) versus CA-MRSA (4.76%). Against a low initial inoculum of 106 cfu/ml of CA-MRSA, vancomycin pharmacodynamics were similar among agr functional and dysfunctional strains. However, against a high initial inoculum of 108 cfu/ml, killing activity was notably attenuated against agr dysfunctional CA-MRSA (USA400) and HA-MRSA (USA100). CA-MRSA displayed a 20.0 fold decrease in the maximal reduction in bacterial counts (Emax) which was 3.71 log10 CFU/ml for agr functional vs. 2.41 log10 CFU/ml for agr dysfunctional MRSA (p = 0.0007). Conclusions Dysfunction in agr was less common among CA-MRSA vs. HA-MRSA. agr dysfunction demonstrated an impact on vancomycin bactericidal activity and pharmacodynamics against a high initial inoculum of CA-MRSA and HA-MRSA, which may have implications for optimal antimicrobial therapy against persistent, difficult to treat MRSA infections. PMID:21599878

Impact of accessory gene regulator (agr) dysfunction on vancomycin pharmacodynamics among Canadian community and health-care associated methicillin-resistant Staphylococcus aureus.

PubMed

Tsuji, Brian T; MacLean, Robert D; Dresser, Linda D; McGavin, Martin J; Simor, Andrew E

2011-05-20

The accessory gene regulator (agr) is a quorum sensing cluster of genes which control colonization and virulence in Staphylococcus aureus. We evaluated agr function in community- (CA) and healthcare-associated (HA) MRSA, to compare the pharmacodynamics and bactericidal activity of vancomycin against agr functional and dysfunctional HA-MRSA and CA-MRSA. 40 clinical isolates of MRSA from the Canadian Nosocomial Infection Surveillance Program were evaluated for delta-haemolysin production, as a surrogate marker of agr function. Time kill experiments were performed for vancomycin at 0 to 64 times the MIC against an initial inoculum of 10(6) and 10(8) cfu/ml of agr functional and dysfunctional CA-MRSA and HA-MRSA and these data were fit to a hill-type pharmacodynamic model. 15% isolates were agr dysfunctional, which was higher among HA-MRSA (26.3%) versus CA-MRSA (4.76%). Against a low initial inoculum of 10(6) cfu/ml of CA-MRSA, vancomycin pharmacodynamics were similar among agr functional and dysfunctional strains. However, against a high initial inoculum of 10(8) cfu/ml, killing activity was notably attenuated against agr dysfunctional CA-MRSA (USA400) and HA-MRSA (USA100). CA-MRSA displayed a 20.0 fold decrease in the maximal reduction in bacterial counts (Emax) which was 3.71 log(10) CFU/ml for agr functional vs. 2.41 log(10) CFU/ml for agr dysfunctional MRSA (p = 0.0007). Dysfunction in agr was less common among CA-MRSA vs. HA-MRSA. agr dysfunction demonstrated an impact on vancomycin bactericidal activity and pharmacodynamics against a high initial inoculum of CA-MRSA and HA-MRSA, which may have implications for optimal antimicrobial therapy against persistent, difficult to treat MRSA infections.

Inoculum size-dependent interactive regulation of metabolism and stress response of Saccharomyces cerevisiae revealed by comparative metabolomics.

PubMed

Ding, Ming-Zhu; Tian, Hong-Chi; Cheng, Jing-Sheng; Yuan, Ying-Jin

2009-12-01

To investigate the metabolic regulation against inoculum density and stress response to high cell density, comparative metabolomic analysis was employed on Saccharomyces cerevisiae under fermentations with five different inoculum sizes by gas chromatography time-of-flight mass spectrometry. Samples from these fermentations were clearly distinguished by principal components analysis, indicating that inoculum size had a profound effect on the metabolism of S. cerevisiae. Potential biomarkers responsible for the discrimination were identified as glycerol, phosphoric acid, succinate, glycine, isoleucine, proline, palmitoleic acid, myo-inositol and ethanolamine. It indicated that enhanced stress protectants in glycerol biosynthesis and amino acid metabolism, depressed citric acid cycle intermediates, as well as decreased metabolites relating to membrane structure and function were involved as the inoculum size of yeast increased. Furthermore, significantly higher levels of glycerol and proline in yeast cells of higher inoculum size fermentation (40 g l(-1)) revealed that they played important roles in protecting yeast from stresses in high cell density fermentation. These findings provided new insights into characterizing the metabolic regulation and stress response depending on inoculum density during ethanol fermentation.

Methanosarcina plays a main role during methanogenesis of high-solids food waste and cardboard.

PubMed

Capson-Tojo, Gabriel; Trably, Eric; Rouez, Maxime; Crest, Marion; Bernet, Nicolas; Steyer, Jean-Philippe; Delgenès, Jean-Philippe; Escudié, Renaud

2018-04-07

Anaerobic digestion of food waste is a complex process often hindered by high concentrations of volatile fatty acids and ammonia. Methanogenic archaea are more sensitive to these inhibitors than bacteria and thus the structure of their community is critical to avoid reactor acidification. In this study, the performances of three different inocula were compared using batch digestion tests of food waste and cardboard mixtures. Particular attention was paid to the archaeal communities in the inocula and after digestion. While the tests started with inocula rich in Methanosarcina led to efficient methane production, VFAs accumulated in the reactors where inocula initially were poor in this archaea and no methane was produced. In addition, higher substrate loads were tolerated when greater proportions of Methanosarcina were initially present in the inoculum. Independently of the inoculum origin, Methanosarcina were the dominant methanogens in the digestates from the experiments that efficiently produced methane. These results suggest that the initial archaeal composition of the inoculum is crucial during reactor start-up to achieve stable anaerobic digestion at high concentrations of ammonia and organic acids. Copyright © 2018 Elsevier Ltd. All rights reserved.

In Vivo Pharmacodynamics of Cefquinome in a Neutropenic Mouse Thigh Model of Streptococcus suis Serotype 2 at Varied Initial Inoculum Sizes

PubMed Central

Guo, Chunna; Liao, Xiaoping; Wang, Mingru; Wang, Feng; Yan, Chaoqun; Xiao, Xia; Sun, Jiang

2015-01-01

Streptococcus suis serotype 2 is an emerging zoonotic pathogen and causes severe disease in both pigs and human beings. Cefquinome (CEQ), a fourth-generation cephalosporin, exhibits broad-spectrum activity against Gram-positive bacteria such as S. suis. This study evaluated the in vitro and in vivo antimicrobial activities of CEQ against four strains of S. suis serotype 2 in a murine neutropenic thigh infection model. We investigated the effect of varied inoculum sizes (106 to 108 CFU/thigh) on the pharmacokinetic (PK)/pharmacodynamic (PD) indices and magnitudes of a particular PK/PD index or dose required for efficacy. Dose fractionation studies included total CEQ doses ranging from 0.625 to 640 mg/kg/24 h. Data were analyzed via a maximum effect (Emax) model using nonlinear regression. The PK/PD studies demonstrated that the percentage of time that serum drug levels were above the MIC of free drug (%ƒT>MIC) in a 24-h dosing interval was the primary index driving the efficacy of both inoculum sizes (R2 = 91% and R2 = 63%). CEQ doses of 2.5 and 40 mg/kg body weight produced prolonged postantibiotic effects (PAEs) of 2.45 to 8.55 h. Inoculum sizes had a significant influence on CEQ efficacy. Compared to the CEQ exposure and dosages in tests using standard inocula, a 4-fold dose (P = 0.006) and a 2-fold exposure time (P = 0.01) were required for a 1-log kill using large inocula of 108 CFU/thigh. PMID:26666923

Modified batch anaerobic digestion assay for testing efficiencies of trace metal additives to enhance methane production of energy crops.

PubMed

Brulé, Mathieu; Bolduan, Rainer; Seidelt, Stephan; Schlagermann, Pascal; Bott, Armin

2013-01-01

Batch biochemical methane potential (BMP) assays to evaluate the methane yield of biogas substrates such as energy crops are usually carried out with undiluted inoculum. A BMP assay was performed on two energy crops (green cuttings and grass silage). Anaerobic digestion was performed both with and without supplementation of three commercial additives containing trace metals in liquid, solid or adsorbed form (on clay particles). In order to reveal positive effects of trace metal supplementation on the methane yield, besides undiluted inoculum, 3-fold and 10-fold dilutions of the inoculum were applied for substrate digestion. Diluted inoculum variants were supplemented with both mineral nutrients and pH-buffering substances to prevent a collapse of the digestion process. As expected, commercial additives had no effect on the digestion process performed with undiluted inoculum, while significant increases of methane production through trace element supplementation could be observed on the diluted variants. The effect of inoculum dilution may be twofold: (1) decrease in trace metal supplementation from the inoculum and (2) reduction in the initial number of bacterial cells. Bacteria require higher growth rates for substrate degradation and hence have higher trace element consumption. According to common knowledge of the biogas process, periods with volatile fatty acids accumulation and decreased pH may have occurred in the course ofanaerobic digestion. These effects may have led to inhibition, not only ofmethanogenes and acetogenes involved in the final phases of methane production, but also offibre-degrading bacterial strains involved in polymer hydrolysis. Further research is required to confirm this hypothesis.

Fabrication of biogenic antimicrobial silver nanoparticles by Streptomyces aegyptia NEAE 102 as eco-friendly nanofactory.

PubMed

El-Naggar, Noura El-Ahmady; Abdelwahed, Nayera A M; Darwesh, Osama M M

2014-04-01

The current research was focused on the extracellular biosynthesis of bactericidal silver nanoparticles (AgNPs) using cell-free supernatant of a local isolate previously identified as a novel Streptomyces aegyptia NEAE 102. The biosynthesis of silver nanoparticles by Streptomyces aegyptia NEAE 102 was quite fast and required far less time than previously published strains. The produced particles showed a single surface plasmon resonance peak at 400 nm by UV-Vis spectroscopy, which confirmed the presence of AgNPs. Response surface methodology was chosen to evaluate the effects of four process variables (AgNO3 concentration, incubation period, pH levels, and inoculum size) on the biosynthesis of silver nanoparticles by Streptomyces aegyptia NEAE 102. Statistical analysis of the results showed that the linear and quadratic effects of incubation period, initial pH, and inoculum size had a significant effect (p < 0.05) on the biosynthesis of silver nanoparticles by Streptomyces aegyptia NEAE 102. The maximum silver nanoparticles biosynthesis (2.5 OD, at 400 nm ) was achieved in runs number 5 and 14 under the conditions of 1 mM AgNO3 (1-1.5% (v/v)), incubation period (72-96 h), initial pH (9-10), and inoculum size (2-4% (v/v)). An overall 4-fold increase in AgNPs biosynthesis was obtained as compared with that of unoptimized conditions. The biosynthesized silver nanoparticles were characterized using UV-VIS spectrophotometer and Fourier transform infrared spectroscopy analysis, in addition to antimicrobial properties. The biosynthesized AgNPs significantly inhibited the growth of medically important pathogenic gram-positive (Staphylococcus aureus) and gram-negative bacteria (Pseudomonas aeruginosa) and yeast (Candida albicans).

Hydrolysis of particulate settleable solids (PSS) in activated sludge is determined by the bacteria initially adsorbed in the sewage.

PubMed

Benneouala, Mourad; Bareha, Younès; Mengelle, Evrard; Bounouba, Mansour; Sperandio, Mathieu; Bessiere, Yolaine; Paul, Etienne

2017-11-15

Up to half of the organic fraction of an urban wastewater is made up of particulate settleable solids (PSS). In activated sludge process (AS) this material is rapidly adsorbed on to microbial flocs but is only slowly and partially degraded. To better understand and predict the degradation kinetics observed, a determination of the proportion of hydrolytic bacteria is required. As inoculum is usually added in the biodegradation tests, a comparison is required between the roles of bacteria introduced with the inoculum and those attached to the substrate. In this work, respirometric batch experiments were performed on PSS collected from upstream or downstream of the sewers of Toulouse city. Toilet paper (TP) and cellulose, two model particulate substrates, were also investigated. To understand the role of the active biomass in hydrolysis, increasing concentrations of AS were added to a certain amount of PSS or TP. No correlation was observed between the concentration of AS and the rate and duration of degradation of the particulate matter. Simulations performed after calibration of the model ASM-1 allowed the fraction of hydrolytic bacteria to be estimated in both the substrate and the AS-inoculum. Only a very small fraction of the bacteria of AS and of the substrate samples were found to be efficient for hydrolysis. Hydrolysis was mainly initiated by a small proportion of the microorganisms, and especially by cells already attached to PSSs. Moreover, the fraction of bacteria able to hydrolyse large particles present in an inoculum of AS depended on the initial contamination of the surface of the particles. Copyright © 2017 Elsevier Ltd. All rights reserved.

In Vivo Pharmacodynamics of Cefquinome in a Neutropenic Mouse Thigh Model of Streptococcus suis Serotype 2 at Varied Initial Inoculum Sizes.

PubMed

Guo, Chunna; Liao, Xiaoping; Wang, Mingru; Wang, Feng; Yan, Chaoqun; Xiao, Xia; Sun, Jiang; Liu, Yahong

2016-02-01

Streptococcus suis serotype 2 is an emerging zoonotic pathogen and causes severe disease in both pigs and human beings. Cefquinome (CEQ), a fourth-generation cephalosporin, exhibits broad-spectrum activity against Gram-positive bacteria such as S. suis. This study evaluated the in vitro and in vivo antimicrobial activities of CEQ against four strains of S. suis serotype 2 in a murine neutropenic thigh infection model. We investigated the effect of varied inoculum sizes (10(6) to 10(8) CFU/thigh) on the pharmacokinetic (PK)/pharmacodynamic (PD) indices and magnitudes of a particular PK/PD index or dose required for efficacy. Dose fractionation studies included total CEQ doses ranging from 0.625 to 640 mg/kg/24 h. Data were analyzed via a maximum effect (Emax) model using nonlinear regression. The PK/PD studies demonstrated that the percentage of time that serum drug levels were above the MIC of free drug (%ƒT>MIC) in a 24-h dosing interval was the primary index driving the efficacy of both inoculum sizes (R(2) = 91% and R(2) = 63%). CEQ doses of 2.5 and 40 mg/kg body weight produced prolonged postantibiotic effects (PAEs) of 2.45 to 8.55 h. Inoculum sizes had a significant influence on CEQ efficacy. Compared to the CEQ exposure and dosages in tests using standard inocula, a 4-fold dose (P = 0.006) and a 2-fold exposure time (P = 0.01) were required for a 1-log kill using large inocula of 10(8) CFU/thigh. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Emergence of Distinct Brome Mosaic Virus Recombinants Is Determined by the Polarity of the Inoculum RNA

PubMed Central

Kwon, Sun-Jung

2012-01-01

Despite overwhelming interest in the impact exerted by recombination during evolution of RNA viruses, the relative contribution of the polarity of inoculum templates remains poorly understood. Here, by agroinfiltrating Nicotiana benthamiana leaves, we show that brome mosaic virus (BMV) replicase is competent to initiate positive-strand [(+)-strand] synthesis on an ectopically expressed RNA3 negative strand [(−) strand] and faithfully complete the replication cycle. Consequently, we sought to examine the role of RNA polarity in BMV recombination by expressing a series of replication-defective mutants of BMV RNA3 in (+) or (−) polarity. Temporal analysis of progeny sequences revealed that the genetic makeup of the primary recombinant pool is determined by the polarity of the inoculum template. When the polarity of the inoculum template was (+), the recombinant pool that accumulated during early phases of replication was a mixture of nonhomologous recombinants. These are longer than the inoculum template length, and a nascent 3′ untranslated region (UTR) of wild-type (WT) RNA1 or RNA2 was added to the input mutant RNA3 3′ UTR due to end-to-end template switching by BMV replicase during (−)-strand synthesis. In contrast, when the polarity of the inoculum was (−), the progeny contained a pool of native-length homologous recombinants generated by template switching of BMV replicase with a nascent UTR from WT RNA1 or RNA2 during (+)-strand synthesis. Repair of a point mutation caused by polymerase error occurred only when the polarity of the inoculum template was (+). These results contribute to the explanation of the functional role of RNA polarity in recombination mediated by copy choice mechanisms. PMID:22357282

Dissection of niche competition between introduced and indigenous arbuscular mycorrhizal fungi with respect to soybean yield responses.

PubMed

Niwa, Rieko; Koyama, Takuya; Sato, Takumi; Adachi, Katsuki; Tawaraya, Keitaro; Sato, Shusei; Hirakawa, Hideki; Yoshida, Shigenobu; Ezawa, Tatsuhiro

2018-05-09

Arbuscular mycorrhizal (AM) fungi associate with most land plants and deliver phosphorus to the host. Identification of biotic/abiotic factors that determine crop responses to AM fungal inoculation is an essential step for successful application of the fungi in sustainable agriculture. We conducted three field trials on soybean with a commercial inoculum and developed a new molecular tool to dissect interactions between the inoculum and indigenous fungi on the MiSeq sequencing platform. Regression analysis indicated that sequence read abundance of the inoculum fungus was the most significant factor that determined soybean yield responses to the inoculation, suggesting that dominance of the inoculum fungus is a necessary condition for positive yield responses. Agricultural practices (fallow/cropping in the previous year) greatly affected the colonization levels (i.e. read abundances) of the inoculum fungus via altering the propagule density of indigenous AM fungi. Analysis of niche competition revealed that the inoculum fungus competed mainly with the indigenous fungi that are commonly distributed in the trial sites, probably because their life-history strategy is the same as that of the inoculum fungus. In conclusion, we provide a new framework for evaluating the significance of environmental factors towards successful application of AM fungi in agriculture.

Potential Environmental Factors Affecting Oil-Degrading Bacterial Populations in Deep and Surface Waters of the Northern Gulf of Mexico

PubMed Central

Liu, Jiqing; Bacosa, Hernando P.; Liu, Zhanfei

2017-01-01

Understanding bacterial community dynamics as a result of an oil spill is important for predicting the fate of oil released to the environment and developing bioremediation strategies in the Gulf of Mexico. In this study, we aimed to elucidate the roles of temperature, water chemistry (nutrients), and initial bacterial community in selecting oil degraders through a series of incubation experiments. Surface (2 m) and bottom (1537 m) waters, collected near the Deepwater Horizon site, were amended with 200 ppm light Louisiana sweet crude oil and bacterial inoculums from surface or bottom water, and incubated at 4 or 24°C for 50 days. Bacterial community and residual oil were analyzed by pyrosequencing and gas chromatography-mass spectrometry (GC-MS), respectively. The results showed that temperature played a key role in selecting oil-degrading bacteria. Incubation at 4°C favored the development of Cycloclasticus, Pseudoalteromonas, Sulfitobacter, and Reinekea, while 24°C incubations enhanced Oleibacter, Thalassobius, Phaeobacter, and Roseobacter. Water chemistry and the initial community also had potential roles in the development of hydrocarbon-degrading bacterial communities. Pseudoalteromonas, Oleibacter, and Winogradskyella developed well in the nutrient-enriched bottom water, while Reinekea and Thalassobius were favored by low-nutrient surface water. We revealed that the combination of 4°C, crude oil and bottom inoculum was a key factor for the growth of Cycloclasticus, while the combination of surface inoculum and bottom water chemistry was important for the growth of Pseudoalteromonas. Moreover, regardless of the source of inoculum, bottom water at 24°C was a favorable condition for Oleibacter. Redundancy analysis further showed that temperature and initial community explained 57 and 19% of the variation observed, while oil and water chemistry contributed 14 and 10%, respectively. Overall, this study revealed the relative roles of temperature, water chemistry, and initial bacterial community in selecting oil degraders and regulating their evolution in the northern Gulf of Mexico. PMID:28119669

Potential Environmental Factors Affecting Oil-Degrading Bacterial Populations in Deep and Surface Waters of the Northern Gulf of Mexico.

PubMed

Liu, Jiqing; Bacosa, Hernando P; Liu, Zhanfei

2016-01-01

Understanding bacterial community dynamics as a result of an oil spill is important for predicting the fate of oil released to the environment and developing bioremediation strategies in the Gulf of Mexico. In this study, we aimed to elucidate the roles of temperature, water chemistry (nutrients), and initial bacterial community in selecting oil degraders through a series of incubation experiments. Surface (2 m) and bottom (1537 m) waters, collected near the Deepwater Horizon site, were amended with 200 ppm light Louisiana sweet crude oil and bacterial inoculums from surface or bottom water, and incubated at 4 or 24°C for 50 days. Bacterial community and residual oil were analyzed by pyrosequencing and gas chromatography-mass spectrometry (GC-MS), respectively. The results showed that temperature played a key role in selecting oil-degrading bacteria. Incubation at 4°C favored the development of Cycloclasticus, Pseudoalteromonas , Sulfitobacter , and Reinekea , while 24°C incubations enhanced Oleibacter, Thalassobius, Phaeobacter, and Roseobacter. Water chemistry and the initial community also had potential roles in the development of hydrocarbon-degrading bacterial communities. Pseudoalteromonas , Oleibacter , and Winogradskyella developed well in the nutrient-enriched bottom water, while Reinekea and Thalassobius were favored by low-nutrient surface water. We revealed that the combination of 4°C, crude oil and bottom inoculum was a key factor for the growth of Cycloclasticus , while the combination of surface inoculum and bottom water chemistry was important for the growth of Pseudoalteromonas . Moreover, regardless of the source of inoculum, bottom water at 24°C was a favorable condition for Oleibacter. Redundancy analysis further showed that temperature and initial community explained 57 and 19% of the variation observed, while oil and water chemistry contributed 14 and 10%, respectively. Overall, this study revealed the relative roles of temperature, water chemistry, and initial bacterial community in selecting oil degraders and regulating their evolution in the northern Gulf of Mexico.

Effect of cellobiose supplementation and dietary soluble fibre content on in vitro caecal fermentation of carbohydrate-rich substrates in rabbits.

PubMed

Ocasio-Vega, César; Abad-Guamán, Rodrigo; Delgado, Rebeca; Carabaño, Rosa; Carro, María Dolores; García, Javier

2018-06-01

The in vitro caecal fermentation of five substrates low in starch and protein content [d-(+)-glucose (GLU), d-cellobiose (CEL), sugar beet pectin (PEC), sugar beet pulp (SBP) and wheat straw (WS)] was investigated using soft faeces from rabbits receiving different levels of cellobiose and soluble fibre as inoculum. A total of 24 rabbits were supplemented 3 levels of cellobiose in the drinking water (0.0, 7.5, 15.0 g/l) and fed two experimental diets containing either low soluble fibre (LSF) or high soluble fibre (HSF) levels (84.0 and 130 g/kg dry matter). All substrates were subjected to a two-step pepsin/pancreatin in vitro pre-digestion, and the whole residue was used as substrate for the in vitro incubations. Gas production was measured until 144 h, and volatile fatty acid (VFA) production was determined at 24 h incubation. Experimental treatments did not affect SBP fermentation and had only a subtle influence on fermentation of WS and GLU. In contrast, cellobiose supplementation × donors' diet interactions were detected for most gas production parameters for CEL. Both the fractional gas production (k) and maximal gas production rates were linearly increased (p ≤ 0.042) and the initial delay in the onset of gas production (Lag) linearly decreased (p < 0.001) by cellobiose supplementation with the HSF inoculum, with no differences between the 7.5 and 15.0 doses. In contrast, with the LSF inoculum cellobiose supplementation only affected k values, which were quadratically increased (p = 0.043) and had maximal values for the 7.5 dose. A quadratic effect (p ≤ 0.018) of cellobiose supplementation was observed for total VFA production at 24 h when CEL and PEC were fermented, obtaining the maximal VFA production for the 7.5 dose of cellobiose. Total VFA production for CEL was greater with LSF than with HSF inoculum (20.7 vs. 12.9 mmol/l; p = 0.014), but the opposite was found for WS (3.97 vs. 6.21 mmol/l; p = 0.005). The use of LSF inoculum for CEL fermentation sharply reduced acetate (p = 0.001) and increased butyrate proportions (p ≤ 0.001) compared with the HSF inoculum. A positive relationship between total VFA caecal concentrations in rabbits receiving the same experimental treatments and in vitro values was only observed when WS was used as substrate (r = 0.90; p = 0.015; n = 6). The results suggest that experimental factors influenced the fermentative activity of caecal digesta, but the observed response differed with the incubated substrate, being the CEL the most affected.

Long-term kinetics of Salmonella Typhimurium ATCC 14028 survival on peanuts and peanut confectionery products

PubMed Central

Carminati, Joyce A.; Morishita, Karen N.; Amorim Neto, Dionísio P.; Pinheiro, Hildete P.; Maia, Rafael P.

2018-01-01

Due to recent large outbreaks, peanuts have been considered a product of potential risk for Salmonella. Usually, peanut products show a low water activity (aw) and high fat content, which contribute to increasing the thermal resistance and survival of Salmonella. This study evaluated the long-term kinetics of Salmonella survival on different peanut products under storage at 28°C for 420 days. Samples of raw in-shell peanuts (aw = 0.29), roasted peanuts (aw = 0.39), unblanched peanut kernel (aw = 0.54), peanut brittle (aw = 0.30), paçoca (aw = 0.40) and pé-de-moça (aw = 0.68) were inoculated with Salmonella Typhimurium ATCC 14028 at two inoculum levels (3 and 6 log cfu/ g). The Salmonella behavior was influenced (p<0.05) by aw, lipid, carbohydrate and protein content. In most cases for both inoculum levels, the greatest reductions were seen after the first two weeks of storage, followed by a slower decline phase. The lowest reductions were verified in paçoca and roasted peanuts, with counts of 1.01 and 0.87 log cfu/ g at low inoculum level and 2.53 and 3.82 log cfu/ g at high inoculum level at the end of the storage time. The highest loss of viability was observed in pé-de-moça, with absence of Salmonella in 10-g after 180 days at low inoculum level. The Weibull model provided a suitable fit to the data (R2≥0.81), with δ value ranging from 0.06 to 49.75 days. Therefore, the results demonstrated that Salmonella survives longer in peanut products, beyond the shelf life (>420 days), especially in products with aw around 0.40. PMID:29401480

Etiology and Epidemiological Conditions Promoting Fusarium Root Rot in Sweetpotato.

PubMed

Scruggs, A C; Quesada-Ocampo, L M

2016-08-01

Sweetpotato production in the United States is limited by several postharvest diseases, and one of the most common is Fusarium root rot. Although Fusarium solani is believed to be the primary causal agent of disease, numerous other Fusarium spp. have been reported to infect sweetpotato. However, the diversity of Fusarium spp. infecting sweetpotato in North Carolina is unknown. In addition, the lack of labeled and effective fungicides for control of Fusarium root rot in sweetpotato creates the need for integrated strategies to control disease. Nonetheless, epidemiological factors that promote Fusarium root rot in sweetpotato remain unexplored. A survey of Fusarium spp. infecting sweetpotato in North Carolina identified six species contributing to disease, with F. solani as the primary causal agent. The effects of storage temperature (13, 18, 23, 29, and 35°C), relative humidity (80, 90, and 100%), and initial inoculum level (3-, 5-, and 7-mm-diameter mycelia plug) were examined for progression of Fusarium root rot caused by F. solani and F. proliferatum on 'Covington' sweetpotato. Fusarium root rot was significantly reduced (P < 0.05) at lower temperatures (13°C), low relative humidity levels (80%), and low initial inoculum levels for both pathogens. Sporulation of F. proliferatum was also reduced under the same conditions. Qualitative mycotoxin analysis of roots infected with one of five Fusarium spp. revealed the production of fumonisin B1 by F. proliferatum when infecting sweetpotato. This study is a step toward characterizing the etiology and epidemiology of Fusarium root rot in sweetpotato, which allows for improved disease management recommendations to limit postharvest losses to this disease.

Variability in Cell Response of Cronobacter sakazakii after Mild-Heat Treatments and Its Impact on Food Safety

PubMed Central

Parra-Flores, Julio; Juneja, Vijay; Garcia de Fernando, Gonzalo; Aguirre, Juan

2016-01-01

Cronobacter spp. have been responsible for severe infections in infants associated with consumption of powdered infant formula and follow-up formulae. Despite several risk assessments described in published studies, few approaches have considered the tremendous variability in cell response that small micropopulations or single cells can have in infant formula during storage, preparation or post process/preparation before the feeding of infants. Stochastic approaches can better describe microbial single cell response than deterministic models as we prove in this study. A large variability of lag phase was observed in single cell and micropopulations of ≤50 cells. This variability increased as the heat shock increased and growth temperature decreased. Obviously, variability of growth of individual Cronobacter sakazakii cell is affected by inoculum size, growth temperature and the probability of cells able to grow at the conditions imposed by the experimental conditions should be taken into account, especially when errors in bottle-preparation practices, such as improper holding temperatures, or manipulation, may lead to growth of the pathogen to a critical cell level. The mean probability of illness from initial inoculum size of 1 cell was below 0.2 in all the cases and for inoculum size of 50 cells the mean probability of illness, in most of the cases, was above 0.7. PMID:27148223

Inoculum Effects of Ceftobiprole, Daptomycin, Linezolid, and Vancomycin with Staphylococcus aureus and Streptococcus pneumoniae at Inocula of 105 and 107 CFU Injected into Opposite Thighs of Neutropenic Mice

PubMed Central

Lee, Dong-Gun; Murakami, Yoichi; Andes, David R.

2013-01-01

Reduced bactericidal efficacy at a high inoculum is known as the inoculum effect (IE). We used neutropenic mice to compare the IEs of ceftobiprole (CFB), daptomycin (DAP), linezolid (LZD), and vancomycin (VAN) against 6 to 9 strains of Staphylococcus aureus and 4 strains of Streptococcus pneumoniae at 2 inocula in opposite thighs of the same mice. Neutropenic mice had 104.5 to 105.7 CFU/thigh (low inoculum [LI]) in one thigh and 106.4 to 107.2 CFU/thigh (high inoculum [HI]) in the opposite thigh when treated for 24 h with subcutaneous (s.c.) doses every 12 h of DAP at 0.024 to 100 mg/kg of body weight and LZD at 0.313 to 320 mg/kg and s.c. doses every 6 h of CFB at 0.003 to 160 mg/kg and VAN at 0.049 to 800 mg/kg. Dose-response data were analyzed by a maximum effect (Emax) model using nonlinear regression. Static doses for each drug and at each inoculum were calculated, and the difference between HI and LI (IE index) gave the magnitude of IE for each drug-organism combination. Mean (range) IE indexes of S. aureus were 2.9 (1.7 to 4.6) for CFB, 4.1 (2.6 to 9.3) for DAP, 4.6 (1.7 to 7.1) for LZD, and 10.1 (6.3 to 20.3) for VAN. In S. pneumoniae, the IE indexes were 2.5 (1.3 to 3.3) for CFB, 2.0 (1.6 to 2.8) for DAP, 1.9 (1.7 to 2.2) for LZD, and 1.5 (0.8 to 3.2) for VAN; these values were similar for all drugs. In S. aureus, the IE was much larger with VAN than with CFB, DAM, and LZD (P < 0.05). An in vivo time course of vancomycin activity showed initiation of killing at 4- to 16-fold-higher doses at HI than at LI despite similar initial growth of controls. PMID:23295932

The effect of different initial densities of nematode (Meloidogyne javanica) on the build-up of Pasteuria penetrans population.

PubMed

Darban, Daim Ali; Pathan, Mumtaz Ali; Bhatti, Abdul Ghaffar; Maitelo, Sultan Ahmed

2005-02-01

Pasteuria penetrans will build-up faster where there is a high initial nematode density and can suppress root-knot nematode populations in the roots of tomato plants. The effect of different initial densities of nematode (Meloidogyne javanica) (150, 750, 1500, 3000) and P. penetrans infected females (F1, F3) densities (F0=control and AC=absolute control without nematode or P. penetrans inoculum) on the build-up of Pasteuria population was investigated over four crop cycles. Two major points of interest were highlighted. First, that within a confined soil volume, densities of P. penetrans can increase >100 times within 2 or 3 crop cycles. Second, from a relatively small amount of spore inoculum, infection of the host is very high. There were more infected females in the higher P. penetrans doses. The root growth data confirms the greater number of females in the controls particularly at the higher inoculum densities in the third and fourth crops. P. penetrans generally caused the fresh root weights to be higher than those in the control. P. penetrans has shown greater reduction of egg masses per plant at most densities. The effects of different initial densities of M. javanica and P. penetrans on the development of the pest and parasite populations were monitored. And no attempt was made to return the P. penetrans spores to the pots after each crop so the build-up in actual numbers of infected females and spores under natural conditions may be underestimated.

Effect of packaging and storage temperature on the survival of Listeria monocytogenes inoculated postprocessing on sliced salami.

PubMed

Gounadaki, Antonia S; Skandamis, Panagiotis N; Drosinos, Eleftherios H; Nychas, George-John E

2007-10-01

The survival of postprocess Listeria monocytogenes contamination on sliced salami, stored under the temperatures associated with retail and domestic storage, was investigated. Sliced salami was inoculated with low and high concentrations of L. monocytogenes before being packaged under vacuum or air. Survival of L. monocytogenes was determined after storage of sausages for 45 or 90 days for low or high sample inocula, respectively, at 5, 15, and 25 degrees C. All survival curves of L. monocytogenes were characterized by an initial rapid inactivation within the first days of storage, followed by a second, slower inactivation phase or "tailing." Greater reduction of L. monocytogenes was observed at the high storage temperature (25 degrees C), followed by ambient (15 degrees C) and chill (5 degrees C) storage conditions. Moreover, vacuum packaging resulted in a slower destruction of L. monocytogenes than air packaging, and this effect increased as storage temperature decreased. Although L. monocytogenes numbers decreased to undetectable levels by the end of the storage period, the time (in days) needed for this reduction and for the total elimination of the pathogen decreased with high temperature, aerobic storage, and high inoculum. Results of this study clearly indicated that the kinetics of L. monocytogenes were highly dependent on the interaction of factors such as storage temperature, packaging conditions, and initial level of contamination (inoculum). These results may contribute to the exposure assessment of quantitative microbial risk assessment and to the establishment of storage-packaging recommendations of fermented sausages.

Effect of cultivating conditions on alpha-galactosidase production by a novel Aspergillus foetidus ZU-G1 strain in solid-state fermentation.

PubMed

Liu, Cai-qin; Chen, Qi-he; Cheng, Qian-jun; Wang, Jin-ling; He, Guo-qing

2007-05-01

The work is intended to achieve optimum culture conditions of alpha-galactosidase production by a mutant strain Aspergillus foetidus ZU-G1 in solid-state fermentation (SSF). Certain fermentation parameters involving moisture content, incubation temperature, cultivation period of seed, inoculum volume, initial pH value, layers of pledget, load size of medium and period of cultivation were investigated separately. The optimal cultivating conditions of alpha-galactosidase production in SSF were 60% initial moisture of medium, 28 degrees C incubation temperature, 18 h cultivation period of seed, 10% inoculum volume, 5.0 approximately 6.0 initial pH of medium, 6 layers of pledget and 10 g dry matter loadage. Under the optimized cultivation conditions, the maximum alpha-galactosidase production was 2 037.51 U/g dry matter near the 144th hour of fermentation.

Effect of cultivating conditions on α-galactosidase production by a novel Aspergillus foetidus ZU-G1 strain in solid-state fermentation

PubMed Central

Liu, Cai-qin; Chen, Qi-he; Cheng, Qian-jun; Wang, Jin-ling; He, Guo-qing

2007-01-01

The work is intended to achieve optimum culture conditions of α-galactosidase production by a mutant strain Aspergillus foetidus ZU-G1 in solid-state fermentation (SSF). Certain fermentation parameters involving moisture content, incubation temperature, cultivation period of seed, inoculum volume, initial pH value, layers of pledget, load size of medium and period of cultivation were investigated separately. The optimal cultivating conditions of α-galactosidase production in SSF were 60% initial moisture of medium, 28 °C incubation temperature, 18 h cultivation period of seed, 10% inoculum volume, 5.0~6.0 initial pH of medium, 6 layers of pledget and 10 g dry matter loadage. Under the optimized cultivation conditions, the maximum α-galactosidase production was 2 037.51 U/g dry matter near the 144th hour of fermentation. PMID:17542067

Survival of bioluminescent Listeria monocytogenes and Escherichia coli O157:H7 in soft cheeses.

PubMed

Ramsaran, H; Chen, J; Brunke, B; Hill, A; Griffiths, M W

1998-07-01

Pasteurized and raw milks that had been inoculated at 10(4) cfu/ml with bioluminescent strains of Listeria monocytogenes and Escherichia coli O157:H7 were used in the manufacture of Camembert and Feta cheeses with or without nisin-producing starter culture. Survival of both organisms was determined during the manufacture and storage of Camembert and Feta cheeses at 2 +/- 1 degree C for 65 and 75 d, respectively. Bacterial bioluminescence was used as an indicator to enumerate the colonies plated on selective Listeria agar and on MacConkey agar. Escherichia coli O157:H7 survived the manufacturing process of both cheeses and was present at the end of the storage period in greater numbers than in the initial inoculum. At the end of 75 d of storage, E. coli O157:H7 was found in the brine of Feta cheese. The counts of L. monocytogenes increased as the pH of the Camembert cheese increased, and there were significant differences between the counts from samples taken from the inside and the counts from samples obtained near the surface of the cheese. The Feta cheese that contained nisin was the only cheese in which L. monocytogenes was at the level of the initial inoculum after 75 d of storage.

Preparation and Antioxidant Activity of Purple Potato Wine

PubMed Central

Zhong-hua, Liu; Jie, Guo

2015-01-01

Purple potatoes were used as raw material to study the purple potato wine production process and antioxidant activity. This paper analyzed different fermentation time, fermentation temperature, yeast inoculum, initial pH, the initial sugar content on alcohol and anthocyanin contents of purple potato wine by single factor experiments and response surface methodology(RSM). The results showed that the optimum fermentation conditions of purple potato wine were as follows: fermentation temperature was 26oC, yeast inoculum was 0.15%, fermentation time was 7 d, initial pH was 3.0 and initial sugar content was 11 %. Under these conditions the alcohol and anthocyanin contents of purple potato wine could reach 10.55%/Vol and 6.42 μg/mL, respectively. The purple potato wine was purple, bright in colour, pleasant fragrance and pure taste. Prepared purple potato wine had the ability of reducing Fe3+ and scavenging superoxide anion radicals, which meant that purple potato wine had certain antioxidant activity. PMID:26998173

Linking microbial community structure and product spectrum of rice straw fermentation with undefined mixed culture

NASA Astrophysics Data System (ADS)

Ai, Binling; Chi, Xue; Meng, Jia; Sheng, Zhanwu; Zheng, Lili; Zheng, Xiaoyan; Li, Jianzheng

2017-12-01

Undefined mixed culture-based fermentation is an alternative strategy for biofuels and bioproducts production from lignocellulosic biomass without supplementary cellulolytic enzymes. Mixed culture produces mixed carboxylates. To estimate the relationship between microbial community structure and product spectrum, carboxylate production was initiated by mixed cultures with different microbial community structure. All the inoculum cultures were derived from the same enrichment culture from the combination of cattle manure, pig manure compost, corn field soil and rotten wood. Due to the differences in the preparation method and culture time, the inoculum cultures for batch fermentation had high similarity in microbial community structure, while the community structure of each inoculum culture for repeated batch fermentation differed from that of another. The inoculum cultures with similar community structure led to a similar product spectrum. In batch fermentation, the selectivity of main product butyric acid stabilized around 76%. The inoculum cultures with different community structures resulted in different product spectra. In repeated batch fermentation, the butyric acid content gradually decreased to 27%, and the by-product acetic acid content steadily increased to 56%. The other by-products including propionic, valeric and caproic acids were also increased. It is deduced that keeping the microbial community structure stable makes the basic and key precondition for steady production of specific carboxylic acid with undefined mixed culture.

The production and activity test of cellulases using bagasse substrate on Aspergillus niger isolated from Clove field, Kare, Madiun

NASA Astrophysics Data System (ADS)

Ardhi, Muh. Waskito; Sulistyarsi, Ani; Pujiati

2017-06-01

Aspergillus sp is a microorganism which has a high ability to produce cellulase enzymes. In producing Cellulase enzymes requires appropriate concentration and incubation time to obtain optimum enzyme activity. This study aimed to determine the effect of inoculum concentration and incubation time towards production and activity of cellulases from Aspergillus sp substrate bagasse. This research used experiments method; completely randomized design with 2 factorial repeated 2 times. The treatment study include differences inoculum (K) 5% (K1), 15% (K2) 25%, (K3) and incubation time (F) that is 3 days (F1), 6 days (F2), 9 days (F3), 12 days (F4). The data taken from the treatment are glucose reduction and protein levels of crude cellulase enzyme activity that use Nelson Somogyi and Biuret methods. Analysis of variance ANOVA data used two paths with significance level of 5% then continued with LSD test. The results showed that: Fhit>Ftab. Thus, there is effect of inoculum concentrations and incubation time toward activity of crude cellulases of Aspergillus sp. The highest glucose reduction of treatment is K3F4 (concentration of inoculum is 25% with 12 days incubation time) amount 12.834 g / ml and the highest protein content is K3F4 (concentration of inoculum is 25% with with 12 days incubation time) amount 0.740 g / ml.

Versatility of Streptomyces sp. M7 to bioremediate soils co-contaminated with Cr(VI) and lindane.

PubMed

Aparicio, JuanDaniel; Solá, María Zoleica Simón; Benimeli, Claudia Susana; Amoroso, María Julia; Polti, Marta Alejandra

2015-06-01

The aim of this work was to study the impact of environmental factors on the bioremediation of Cr(VI) and lindane contaminated soil, by an actinobacterium, Streptomyces sp. M7, in order to optimize the process. Soil samples were contaminated with 25 µg kg(-1) of lindane and 50 mg kg(-1) of Cr(VI) and inoculated with Streptomyces sp. M7. The lowest inoculum concentration which simultaneously produced highest removal of Cr(VI) and lindane was 1 g kg(-1). The influence of physical and chemical parameters was assessed using a full factorial design. The factors and levels tested were: Temperature: 25, 30, 35°C; Humidity: 10%, 20%, 30%; Initial Cr(VI) concentration: 20, 50, 80 mg kg(-1); Initial lindane concentration: 10, 25, 40 µg kg(-1). Streptomyces sp. M7 exhibited strong versatility, showing the ability to bioremediate co-contaminated soil samples at several physicochemical conditions. Streptomyces sp. M7 inoculum size was optimized. Also, it was fitted a model to study this process, and it was possible to predict the system performance, knowing the initial conditions. Moreover, optimum temperature and humidity conditions for the bioremediation of soil with different concentrations of Cr(VI) and lindane were determined. Lettuce seedlings were a suitable biomarker to evaluate the contaminants mixture toxicity. Streptomyces sp. M7 carried out a successful bioremediation, which was demonstrated through ecotoxicity test with Lactuca sativa. Copyright © 2015 Elsevier Inc. All rights reserved.

The survival of salmonellas in shell eggs cooked under simulated domestic conditions.

PubMed Central

Humphrey, T. J.; Greenwood, M.; Gilbert, R. J.; Rowe, B.; Chapman, P. A.

1989-01-01

Strains of Salmonella enteritidis, S. typhimurium and S. senftenberg inoculated into the yolks of shell eggs were found to survive forms of cooking where some of the yolk remained liquid. Survival was largely independent of the size of the initial inoculum. The organisms also grew rapidly in eggs stored at room temperature and after 2 days the number of cells per gram of yolk exceeded log10 8.0. With this level of contamination viable cells could be recovered from eggs cooked in any manner. PMID:2673824

Toxicity of DEDGN (Diethyleneglycol Dinitrate), Synthetic-HC Smoke Combustion Products, Solvent Yellow 33 and Solvent Green 3 to Freshwater Aquatic Organisms.

DTIC Science & Technology

1987-01-15

stock mixture of these components caused both an algistatic and algicidal effect on the alga. The rainbow trout and the water flea had 96-h and 48-h...stock mixture of these components caused both an algistatic and algicidal effect on the alga. LC50 values for the rainbow trout and the water flea...growth period, cell counts did not increase significantly from the initial inoculum level. 2. Algicidal concentration. This is the lowest concentration

Toxicity of DEGDN (Diethyleneglycol Dinitrate), Synthetic-HC Smoke Combustion Products, Solvent Yellow 33 and Solvent Green 3 to Freshwater Aquatic Organisms. Phase 2

DTIC Science & Technology

1987-01-15

algicidal effect on the * alga. LC50 values for the rainbow trout and the water flea were 2.2% and 9.3% of the stock solution, respectively. Additional...significantly from the initial inoculum level. " Algicidal concentration. This is the lowest concentration tested which causes an apparent algistatic...86.9 - 335.5 mg/L). The minimum algicidal concentration was greater than 542.4 mg/L, the highest concentration tested. When algal cultures from this

Diversity of trends of viremia and T-cell markers in experimental acute feline immunodeficiency virus infection.

PubMed

Roche, Sylvain; El Garch, Hanane; Brunet, Sylvie; Poulet, Hervé; Iwaz, Jean; Ecochard, René; Vanhems, Philippe

2013-01-01

The early events of human immunodeficiency virus infection seem critical for progression toward disease and antiretroviral therapy initiation. We wanted to clarify some still unknown prognostic relationships between inoculum size and changes in various immunological and virological markers. Feline immunodeficiency virus infection could be a helpful model. Viremia and T-cell markers (number of CD4, CD8, CD8β(low)CD62L(neg) T-cells, CD4/CD8 ratio, and percentage of CD8β(low)CD62L(neg) cells among CD8 T-cells) were measured over 12 weeks in 102 cats infected with different feline immunodeficiency virus strains and doses. Viremia and T-cell markers trajectory groups were determined and the dose-response relationships between inoculum titres and trajectory groups investigated. Cats given the same inoculum showed different patterns of changes in viremia and T-cell markers. A statistically significant positive dose-response relationship was observed between inoculum titre and i) viremia trajectory-groups (r = 0.80, p<0.01), ii) CD8β(low)CD62L(neg) cell-fraction trajectory-groups (r = 0.56, p<0.01). Significant correlations were also found between viremia and the CD4/CD8 ratio and between seven out of ten T-cell markers. In cats, the infectious dose determines early kinetics of viremia and initial CD8+ T-cell activation. An expansion of the CD8β(low)CD62L(neg) T-cells might be an early predictor of progression toward disease. The same might be expected in humans but needs confirmation.

Deterministic mechanisms define the long-term anaerobic digestion microbiome and its functionality regardless of the initial microbial community.

PubMed

Peces, M; Astals, S; Jensen, P D; Clarke, W P

2018-05-17

The impact of the starting inoculum on long-term anaerobic digestion performance, process functionality and microbial community composition remains unclear. To understand the impact of starting inoculum, active microbial communities from four different full-scale anaerobic digesters were each used to inoculate four continuous lab-scale anaerobic digesters, which were operated identically for 295 days. Digesters were operated at 15 days solid retention time, an organic loading rate of 1 g COD L r -1 d -1 (75:25 - cellulose:casein) and 37 °C. Results showed that long-term process performance, metabolic rates (hydrolytic, acetogenic, and methanogenic) and microbial community are independent of the inoculum source. Digesters process performance converged after 80 days, while metabolic rates and microbial communities converged after 120-145 days. The convergence of the different microbial communities towards a core-community proves that the deterministic factors (process operational conditions) were a stronger driver than the initial microbial community composition. Indeed, the core-community represented 72% of the relative abundance among the four digesters. Moreover, a number of positive correlations were observed between higher metabolic rates and the relative abundance of specific microbial groups. These correlations showed that both substrate consumers and suppliers trigger higher metabolic rates, expanding the knowledge of the nexus between microorganisms and functionality. Overall, these results support that deterministic factors control microbial communities in bioreactors independently of the inoculum source. Hence, it seems plausible that a desired microbial composition and functionality can be achieved by tuning process operational conditions. Copyright © 2018. Published by Elsevier Ltd.

Dispersal of Beauveria bassiana by the activity of nettle insects.

PubMed

Meyling, Nicolai V; Pell, Judith K; Eilenberg, Jørgen

2006-10-01

Recent studies have shown that the entomopathogenic fungus Beauveria bassiana occurs naturally on the phylloplanes of several plants, including nettles. Insects could, by their activity, be contributing to this inoculum by dispersing it from other sites. The potential of nettle aphids Microlophium carnosum and their predator Anthocoris nemorum to disperse conidia of B. bassiana from soil to nettles and from sporulating cadavers in the nettle canopy was investigated in laboratory experiments. In petri dish assays, aphids showed potential to distribute B. bassiana from soil to nettle leaves. Predators dispersed inoculum from both soil and cadavers to nettle leaves in petri dishes. In microcosms, aphids did not disperse B. bassiana from the soil or from cadavers confined in the canopy, but A. nemorum were able to transfer inoculum from soil into the nettle canopy and to distribute conidia from cryptic cadavers. In some instances, infections were initiated in aphids and predators as a consequence of dispersal.

Behavior of Salmonella spp. and natural microbiota on fresh-cut dragon fruits at different storage temperatures.

PubMed

Sim, Hui Li; Hong, Yoon-Ki; Yoon, Won Byong; Yuk, Hyun-Gyun

2013-01-01

The aim of this study was to determine survival or growth of unadapted, acid-adapted and cold-stressed Salmonella spp., and natural microbiota on fresh-cut dragon fruits at different storage temperatures. Dragon fruits were sliced and spot inoculated with five-strain cocktail of Salmonella spp. at two inoculum levels (2.5 or 5.5 log CFU/g). Inoculated fruits were stored at 28°C for 48h and at 4°C and 12°C for 96 h. Salmonella population significantly increased by 2.4 to 3.0 log CFU/g at low inoculum level, whereas the numbers increased by 0.4 to 0.7 log CFU/g at the high inoculum level on fruits held at 28°C for 48h. Only unadapted and acid-adapted cells grew with 0.7 to 0.9log increase at the low inoculum level at 12°C for 96h. No significant growth was observed at both inoculum levels during storage at 4°C. Overall, acid, starved and cold adaptation of Salmonella spp. did not show significant difference in survival or growth on fresh-cut dragon fruits during storage compared to unadapted control cells. For natural microbiota on the fruit, mesophilic bacterial counts reached to 5-log CFU/g at 28 and 12°C by 9.9 and 52.9h. Similar with Salmonella spp. there was no growth of natural microbiota at 4°C. These results showed that Salmonella spp. could grow on fresh-cut dragon fruits under inappropriate storage conditions, indicating that fresh-cut dragon fruits could be a potential vehicle for salmonellosis. Thus, this study suggests that fresh-cut dragon fruits should be stored at 4°C to ensure the safety as well as to extend the shelf life of fresh-cut dragon fruits. Copyright © 2012 Elsevier B.V. All rights reserved.

Experimental rhinovirus infection in volunteers.

PubMed

Bardin, P G; Sanderson, G; Robinson, B S; Holgate, S T; Tyrrell, D A

1996-11-01

Experimental viral disease studies in volunteers have clarified many aspects of the pathogenesis of human viral disease. Recently, interest has focused on rhinovirus-associated asthma exacerbations, and new volunteer studies have suggested that airway responsiveness (AR) is enhanced during a cold. For scientific, ethical and safety reasons, it is important to use validated methods for the preparation of a virus inoculum and that the particular virological characteristics and host responses should not be altered. We have prepared a new human rhinovirus (HRV) inoculum using recent guidelines and assessed whether disease characteristics (for example, severity of colds or changes in AR) were retained. Studies were conducted in 25 clinically healthy volunteers using a validated HRV inoculum in the first 17 and a new inoculum in the subsequent eight subjects. Severity of cold symptoms, nasal wash albumin levels and airway responsiveness were measured, and the new inoculum was prepared from nasal washes obtained during the cold. The new inoculum was tested using standard virological and serological techniques, as well as a polymerase chain reaction for Mycoplasma pneumoniae. No contaminating viruses or organisms were detected and the methods suggested were workable. Good clinical colds developed in 20 of the 25 subjects and median symptom scores were similar in the validated and new inoculum groups (18 and 17.5, respectively; p=0.19). All subjects shed virus, and there were no differences noted in viral culture scores, nasal wash albumin and rates of seroconversion in the two groups. Although airway responsiveness increased in both groups (p=0.02 and p=0.05), the degree of change was similar. We have performed experimental rhinovirus infection studies and demonstrated similar clinical disease in two inoculum groups. Amplified airway responsiveness was induced; continuing studies will define the mechanisms and suggest modes of treatment.

Nitrogen availability of grape juice limits killer yeast growth and fermentation activity during mixed-culture fermentation with sensitive commercial yeast strains.

PubMed Central

Medina, K; Carrau, F M; Gioia, O; Bracesco, N

1997-01-01

The competition between selected or commercial killer strains of type K2 and sensitive commercial strains of Saccharomyces cerevisiae was studied under various conditions in sterile grape juice fermentations. The focus of this study was the effect of yeast inoculation levels and the role of assimilable nitrogen nutrition on killer activity. A study of the consumption of free amino nitrogen (FAN) by pure and mixed cultures of killer and sensitive cells showed no differences between the profiles of nitrogen assimilation in all cases, and FAN was practically depleted in the first 2 days of fermentation. The effect of the addition of assimilable nitrogen and the size of inoculum was examined in mixed killer and sensitive strain competitions. Stuck and sluggish wine fermentations were observed to depend on nitrogen availability when the ratio of killer to sensitive cells was low (1:10 to 1:100). A relationship between the initial assimilable nitrogen content of must and the proportion of killer cells during fermentation was shown. An indirect relationship was found between inoculum size and the percentage of killer cells: a smaller inoculum resulted in a higher proportion of killer cells in grape juice fermentations. In all cases, wines obtained with pure-culture fermentations were preferred to mixed-culture fermentations by sensory analysis. The reasons why killer cells do not finish fermentation under competitive conditions with sensitive cells are discussed. PMID:9212430

Contrasting plant height can improve the control of rain-borne diseases in wheat cultivar mixture: modelling splash dispersal in 3-D canopies.

PubMed

Vidal, T; Gigot, C; de Vallavieille-Pope, C; Huber, L; Saint-Jean, S

2018-06-08

Growing cultivars differing by their disease resistance level together (cultivar mixtures) can reduce the propagation of diseases. Although architectural characteristics of cultivars are little considered in mixture design, they could have an effect on disease, in particular through spore dispersal by rain splash, which occurs over short distances. The objective of this work was to assess the impact of plant height of wheat cultivars in mixtures on splash dispersal of Zymoseptoria tritici, which causes septoria tritici leaf blotch. We used a modelling approach involving an explicit description of canopy architecture and splash dispersal processes. The dispersal model computed raindrop interception by a virtual canopy as well as the production, transport and interception of splash droplets carrying inoculum. We designed 3-D virtual canopies composed of susceptible and resistant plants, according to field measurements at the flowering stage. In numerical experiments, we tested different heights of virtual cultivars making up binary mixtures to assess the influence of this architectural trait on dispersal patterns of spore-carrying droplets. Inoculum interception decreased exponentially with the height relative to the main inoculum source (lower diseased leaves of susceptible plants), and little inoculum was intercepted further than 40 cm above the inoculum source. Consequently, tall plants intercepted less inoculum than smaller ones. Plants with twice the standard height intercepted 33 % less inoculum than standard height plants. In cases when the height of suscpeptible plants was doubled, inoculum interception by resistant leaves was 40 % higher. This physical barrier to spore-carrying droplet trajectories reduced inoculum interception by tall susceptible plants and was modulated by plant height differences between cultivars of a binary mixture. These results suggest that mixture effects on spore dispersal could be modulated by an adequate choice of architectural characteristics of cultivars. In particular, even small differences in plant height could reduce spore dispersal.

Influence of cultivating conditions on the alpha-galactosidase biosynthesis from a novel strain of Penicillium sp. in solid-state fermentation.

PubMed

Wang, C L; Li, D F; Lu, W Q; Wang, Y H; Lai, C H

2004-01-01

The work is intended to achieve optimum culture conditions of alpha-galactosidase production by a mutant strain Penicillium sp. in solid-state fermentation (SSF). Certain fermentation parameters involving incubation temperature, moisture content, initial pH value, inoculum and load size of medium, and incubation time were investigated separately. The optimal temperature and moisture level for alpha-galactosidase biosynthesis was found to be 30 degrees C and 50%, respectively. The range of pH 5.5-6.5 was favourable. About 40-50 g of medium in 250-ml flask and inoculum over 1.0 x 10(6) spores were suitable for enzyme production. Seventy-five hours of incubation was enough for maximum alpha-galactosidase production. Substrate as wheat bran supplemented with soyabean meal and beet pulp markedly improved the enzyme yield in trays. Under optimum culture conditions, the alpha-galactosidase activity from Penicillium sp. MAFIC-6 indicated 185.2 U g(-1) in tray of SSF. The process on alpha-galactosidase production in laboratory scale may have a potentiality of scaling-up.

Chitooligomers preparation by chitosanase produced under solid state fermentation using shrimp by-products as substrate.

PubMed

Nidheesh, T; Pal, Gaurav Kumar; Suresh, P V

2015-05-05

Solid state fermentation (SSF) conditions were statistically optimized for the production of chitosanase by Purpureocillium lilacinum CFRNT12 using shrimp by-products as substrate. Central composite design and response surface methodology were applied to evaluate the effect of variables and their optimization. Incubation temperature, incubation time, concentration of inoculum and yeast extract were found to influence the chitosanase production significantly. The R(2) value of 0.94 indicates the aptness of the model. The level of variables for optimal production of chitosanase was 32 ± 1°C temperature, 96 h incubation, 10.5% (w/v) inoculum, 1.05% (w/w) yeast extract and 65% (w/w) moisture content. The chitosanase production was found to increase from 2.34 ± 0.07 to 41.78 ± 0.73 units/g initial dry substrate after optimization. The crude chitosanase produced 4.43 mM of chitooligomers as exclusive end product from colloidal chitosan hydrolysis. These results indicate the potential of P. lilacinum CFRNT12 for the chitosanase production employing cost effective SSF using shrimp by-products. Copyright © 2014 Elsevier Ltd. All rights reserved.

High density growth of T7 expression strains with auto-induction option

DOEpatents

Studier, F William [Stony Brook, NY

2009-07-14

Disclosed is a method for promoting auto-induction of transcription of cloned DNA in cultures of bacterial cells grown batchwise, the transcription being under the control of a promoter whose activity can be induced by an exogenous inducer whose ability to induce said promoter is dependent on the metabolic state of said bacterial cells. Initially, a culture media is provided which includes: i) an inducer that causes induction of transcription from said promoter in said bacterial cells; and ii) a metabolite that prevents induction by said inducer, the concentration of said metabolite being adjusted so as to substantially preclude induction by said inducer in the early stages of growth of the bacterial culture, but such that said metabolite is depleted to a level that allows induction by said inducer at a later stage of growth. The culture medium is inoculated with a bacterial inoculum, the inoculum comprising bacterial cells containing cloned DNA, the transcription of which is induced by said inducer. The culture is then incubated under conditions appropriate for growth of the bacterial cells.

Inhibition of Listeria monocytogenes by Lactobacillus bavaricus MN in beef systems at refrigeration temperatures.

PubMed Central

Winkowski, K; Crandall, A D; Montville, T J

1993-01-01

The ability of Lactobacillus bavaricus, a meat isolate, to inhibit the growth of three Listeria monocytogenes strains was examined in three beef systems: beef cubes, beef cubes in gravy, and beef cubes in gravy containing glucose. The beef was minimally heat treated, inoculated with L. bavaricus at 10(5) or 10(3) CFU/g and L. monocytogenes at 10(2) CFU/g, vacuum sealed, and stored at 4 or 10 degrees C. The meat samples were monitored for microbial growth, pH, and bacteriocin production. The pathogen was inhibited by L. bavaricus MN. At 4 degrees C, L. monocytogenes was inhibited or killed depending on the initial inoculum level of L. bavaricus. At 10 degrees C, at least a 10-fold reduction of the pathogen occurred, except in the beef without gravy. This system showed a transient inhibition of the pathogen during the first week of storage followed by growth to control levels by the end of the incubation period. Bacteriocin was detected in the samples, and inhibition could not be attributed to acidification. Low refrigeration temperatures significantly (P < or = 0.05) enhanced L. monocytogenes inhibition. Moreover, the addition of glucose-containing gravy and the higher inoculum level of L. bavaricus were significantly (P < or = 0.05) more effective in reducing L. monocytogenes populations in most of the systems studied. PMID:8368843

Effect of low-dose irradiation on growth of and toxin production by Staphylococcus aureus and Bacillus cereus in roast beef and gravy.

PubMed

Grant, I R; Nixon, C R; Patterson, M F

1993-03-01

The effect of irradiation (2 kGy) on growth of and toxin production by Staphylococcus aureus and Bacillus cereus in roast beef and gravy during storage at abuse temperatures (15 and 22 degrees C) was assessed by inoculation studies. Irradiation resulted in a 3-4 log10 reduction in numbers of both pathogens. Whenever B. cereus and S. aureus numbers reached 10(6) and 10(7) cfu/g, respectively, during storage their toxins were detectable. As the time taken to attain these levels was longer in irradiated than in unirradiated samples, toxin production by both pathogens was delayed by irradiation. When samples initially containing low levels (10(2)/g) of S. aureus were irradiated no toxin was produced during subsequent storage at 15 or 22 degrees C. Diarrhoeal toxin produced by B. cereus was detected after 2 days at 22 degrees C, but not at 15 degrees C, in samples containing 10(2) cells/g prior to irradiation. When higher numbers (10(6)/g) of either pathogen were present prior to irradiation, toxins were produced by both pathogens at 22 degrees C, but not at 15 degrees C. Microbial competition had an effect on the growth of B. cereus and S. aureus after irradiation when a low initial inoculum was applied. However, when a higher inoculum was used the pathogens outnumbered their competitors and competition effects were less important. It was concluded that low-dose irradiation would improve the microbiological safety of roast beef and gravy.

Effect of high pressure processing on the survival of Salmonella Enteritidis and shelf-life of chicken fillets.

PubMed

Argyri, Anthoula A; Papadopoulou, Olga S; Nisiotou, Aspasia; Tassou, Chrysoula C; Chorianopoulos, Nikos

2018-04-01

High pressure processing (HPP) is a preservation technology alternative to heat treatment that is mild for food, but effectively inactivates the spoilage microbiota and foodborne pathogens of several foods. The purpose of the current study was to evaluate the effect of HPP on Salmonella ser. Enteritidis, indigenous microbiota and shelf-life of chicken fillets. Chicken fillets were inoculated with S. Enteritidis at three different initial inocula (3, 5, 7 log CFU/g), packed under vacuum, treated or not with HPP (500 MPa/10 min) and stored at 4 and 12 °C. Total viable counts, S. Enteritidis, pseudomonads, Brochothrix thermosphacta, lactic acid bacteria, Enterobacteriaceae and yeasts/molds populations were determined in parallel with sensory analysis of non-inoculated samples. The HPP resulted in the reduction of the pathogen population below the detection limit of the enumeration method (0.48 log CFU/g), irrespective of the inoculum. During the shelf life of the HPP samples, the pathogens population remained below or near the detection limit of the enumeration method at both temperatures, except from the high inoculum case that an increase was observed at 12 °C. At the low inoculum level, the pathogen could not be detected with the enrichment method after the first storage days (2nd day for 4 °C and 0 day for 12 °C). The survival of Salmonella strains was assessed by pulsed field gel electrophoresis and it was shown that the survival of the different strains depended on the inoculum and storage temperature. Regarding the indigenous microbiota, Br. thermosphacta was reported for the first time to be the main spoilage microorganism that survived and dominated after the HPP. From the results it was evident that, HPP may enhance the safety and increase the shelf life (6 at 4 °C and 2 days at 12 °C) of chicken meat. Copyright © 2017 Elsevier Ltd. All rights reserved.

Enhancement of acidogenic fermentation for volatile fatty acid production from food waste: Effect of redox potential and inoculum.

PubMed

Yin, Jun; Yu, Xiaoqin; Zhang, Yeer; Shen, Dongsheng; Wang, Meizhen; Long, Yuyang; Chen, Ting

2016-09-01

The aim of this study was to explore the effects of redox potential (ORP) and inoculum on volatile fatty acids (VFAs) production from food waste by acidogenic fermentation. Four experimental conditions with two ORP levels were tested: limited aeration conditions with ORP level of -100 to -200mV inoculating anaerobic sludge (LA+AnS) or aerobic sludge (LA+AeS), and anaerobic conditions with ORP level of -200 to -300mV inoculating anaerobic sludge with 2-bromoethanosulfophate (AN+BES) and without BES (AN). The maximal VFA yield (0.79g COD/g VS) was attained in LA+AnS reactor due to enhanced hydrolysis of substrates, especially proteins (degradation efficiency 78.3%). A higher frequency of phylum Firmicutes under limited aeration conditions (42.2-48.2%) was observed than that under anaerobic conditions (21.1%). The microbial community was more diverse in LA+AnS reactors than LA+AeS. We conclude that appropriate ORP level (from -100 to -200mV) and inoculum play essential roles in VFA production. Copyright © 2016 Elsevier Ltd. All rights reserved.

Initiation of conidiation in Erysiphe necator is regulated by prior vegetative growth, inoculum density and light

USDA-ARS?s Scientific Manuscript database

Initiation of asexual sporulation in powdery mildews is preceded by a period of superficial vegetative growth of mildew colonies. We found evidence of signaling in Erysiphe necator that was promulgated at the colony center as early as five days after inoculation and stimulated sporulation throughout...

Sclerotinia homoeocarpa Overwinters in Turfgrass and Is Present in Commercial Seed

PubMed Central

Rioux, Renée A.; Shultz, Jeanette; Garcia, Michelle; Willis, David Kyle; Casler, Michael; Bonos, Stacy; Smith, Damon; Kerns, James

2014-01-01

Dollar spot is the most economically important disease of amenity turfgrasses in the United States, yet little is known about the source of primary inoculum for this disease. With the exception of a few isolates from the United Kingdom, Sclerotinia homoeocarpa, the causal agent of dollar spot, does not produce spores. Consequently, it was assumed that overwintering of this organism in soil, thatch, and plant debris provides primary inoculum for dollar spot epidemics. Overwintering of S. homoeocarpa in roots and shoots of symptomatic and asymptomatic creeping bentgrass turfgrass was quantified over the course of a three-year field experiment. Roots did not consistently harbor S. homoeocarpa, whereas S. homoeocarpa was isolated from 30% of symptomatic shoots and 10% of asymptomatic shoots in the spring of two out of three years. The presence of stroma-like pathogen material on leaf blades was associated with an increase in S. homoeocarpa isolation and colony diameter at 48 hpi. Commercial seed has also been hypothesized to be a potential source of initial inoculum for S. homoeocarpa. Two or more commercial seed lots of six creeping bentgrass cultivars were tested for contamination with S. homoeocarpa using culture-based and molecular detection methods. A viable, pathogenic isolate of S. homoeocarpa was isolated from one commercial seed lot and contamination of this lot was confirmed with nested PCR using S. homoeocarpa specific primers. A sensitive nested PCR assay detected S. homoeocarpa contamination in eight of twelve (75%) commercial seed lots. Seed source, but not cultivar or resistance to dollar spot, influenced contamination by S. homoeocarpa. Overall, this research suggests that seeds are a potential source of initial inoculum for dollar spot epidemics and presents the need for further research in this area. PMID:25333928

Study of methanogenesis during bioutilization of plant residuals

NASA Astrophysics Data System (ADS)

Ilyin, V. K.; Korniushenkova, I. N.; Starkova, L. V.; Lauriniavichius, K. S.

2005-02-01

The waste management strategy for the future should meet the benefits of human safety, respect principles of planet ecology, and compatibility with other habitability systems. For these purposes waste management technologies relevant to application of the biodegradation properties of bacteria are of great value. Biological treatment method is based on the biodegradation of organic substances by various microorganisms. The objectives of our study were: to evaluate the effectiveness of microbial biodegradation of vegetable non-edible residual, using artificial inoculum, and to study the peculiarities of biogas, and possibilities of optimizing or reducing the share of methane. The diminution rate of organic gained 76% from initial mass within 9 days of fermentation. The biogas production achieved 46 l/kg of substrate. The microbial studies of biodegradation process revealed the following peculiarities: (i) gradual quantitative increase of Lactobacillus sp. (from 103 to 105 colony-forming units (CFU) per ml); (ii) activation of Clostridia sp. (from 102 to 10 4 CFU/ml); and (iii) elimination of aerobic conventional pathogens (Enterobacteriaceae, Protea sp., Staphylococci). Chromatography analysis revealed the constant presence of carbon dioxide (up to 90.9%). The methane content measures revealed traces 0.1-0.4%. However, when we optimized the methane production in "boiling layer" using methanogenic granules, the amount of methane in biogas reached 80-90%. Based on the results obtained the artificial inoculum was created which was capable of initiating biodegradation of vegetable wastes. This inoculum consisted of active sludge adapted to wastes mixed with excretea of insects which consume plant wastes. Using this inoculum the biodegradation process takes less time than that using active sludge. Regulation of methane concentration from traces to 90% may be achieved by adding methane reactor to the plant digester.

Influence of inoculum density on population dynamics and dauer juvenile yields in liquid culture of biocontrol nematodes Steinernema carpocapsae and S. feltiae (Nematoda: Rhabditida).

PubMed

Hirao, Ayako; Ehlers, Ralf-Udo

2010-01-01

For improvement of mass production of the rhabditid biocontrol nematodes Steinernema carpocapsae and Steinernema feltiae in monoxenic liquid culture with their bacterial symbionts Xenorhabdus nematophila and Xenorhabdus bovienii, respectively, the effect of the initial nematode inoculum density on population development and final concentration of dauer juveniles (DJs) was investigated. Symbiotic bacterial cultures are pre-incubated for 1 day prior to inoculation of DJs. DJs are developmentally arrested and recover development as a reaction to food signals provided by their symbionts. After development to adults, the nematodes produce DJ offspring. Inoculum density ranged from 1 to 10 x 10(3) DJ per milliliter for S. carpocapsae and 1 to 8 x 10(3) DJs per milliliter for S. feltiae. No significant influence of the inoculum density on the final DJ yields in both nematode species was recorded, except for S. carpocapsae cultures with a parental female density <2 x 10(3) DJs per milliliter, in which the yields increased with increasing inoculation density. A strong negative response of the parental female fecundity to increasing DJ inoculum densities was recorded for both species with a maximum offspring number per female of >300 for S. carpocapsae and almost 200 for S. feltiae. The compensative adaptation of fecundity to nematode population density is responsible for the lack of an inoculum (or parental female) density effect on DJ yields. At optimal inoculation density of S. carpocapsae, offspring were produced by the parental female population, whereas S. feltiae always developed a F1 female population, which contributed to the DJ yields and was the reason for a more scattered distribution of the yields. The F1 female generation was accompanied by a second peak in X. bovienii density. The optimal DJ inoculum density for S. carpocapsae is 3-6 x 10(3) DJs per milliliter in order to obtain >10(3) parental females per milliliter. Density-dependent effects were neither observed on the DJ recovery nor on the sex ratio in the parental adult generation. As recovery varied between different batches, assessment of the recovery of inoculum DJ batches is recommended. S. feltiae was less variable in DJ recovery usually reaching >90%. The recommended DJ inoculum density is >5 x 10(3) DJs per milliliter to reach >2 x 10(3) parental females per milliliter. The mean yield recorded for S. carpocapsae was 135 x 10(3) and 105 x 10(3) per mililiter for S. feltiae.

Solid-state Fermentation of Xylanase from Penicillium canescens 10-10c in a Multi-layer-packed Bed Reactor

NASA Astrophysics Data System (ADS)

Assamoi, Antoine A.; Destain, Jacqueline; Delvigne, Frank; Lognay, Georges; Thonart, Philippe

Xylanase is produced by Penicillium canescens 10-10c from soya oil cake in static conditions using solid-state fermentation. The impact of several parameters such as the nature and the size of inoculum, bed-loading, and aeration is evaluated during the fermentation process. Mycelial inoculum gives more production than conidial inoculum. Increasing the quantity of inoculum enhances slightly xylanase production. Forced aeration induces more sporulation of strain and reduces xylanase production. However, forced moistened air improves the production compared to production obtained with forced dry air. In addition, increasing bed-loading reduces the specific xylanase production likely due to the incapacity of the Penicillium strain to grow deeply in the fermented soya oil cake mass. Thus, the best cultivation conditions involve mycelial inoculum form, a bed loading of 1-cm height and passive aeration. The maximum xylanase activity is obtained after 7 days of fermentation and attains 10,200 U/g of soya oil cake. These levels are higher than those presented in the literature and, therefore, show all the potentialities of this stock and this technique for the production of xylanase.

Interaction Between Meloidogyne arenaria and Glomus fascicuqlatus in Grape.

PubMed

Atilano, R A; Menge, J A; Gundy, S D

1981-01-01

Root zones of grape (Fitis vinifera cv Thompson Seedless) cuttings were infested with chlamydospores of Glomus fasciculatus or eggs of Meloidogyne arenaria or both. Growth of grapevines was greatest in mycorrhizal (G. fasciculatus) plants. Mycorrhizal development and growth of mycorrhizal and nonmycorrhizal plants were reduced in the presence of M. arenaria. At low initial nematode inoculum (PI) levels (approx. 200 eggs/plant), the presence of mycorrhizae enhanced plant growth during 1 yr, but no significant benefit was achieved by mycorrhizae where PI was high (approx. 2,000 eggs/plant). Final nematode populations were highest in mycorrhizal plants.

Investigation of antimicrobial activity and statistical optimization of Bacillus subtilis SPB1 biosurfactant production in solid-state fermentation.

PubMed

Ghribi, Dhouha; Abdelkefi-Mesrati, Lobna; Mnif, Ines; Kammoun, Radhouan; Ayadi, Imen; Saadaoui, Imen; Maktouf, Sameh; Chaabouni-Ellouze, Semia

2012-01-01

During the last years, several applications of biosurfactants with medical purposes have been reported. Biosurfactants are considered relevant molecules for applications in combating many diseases. However, their use is currently extremely limited due to their high cost in relation to that of chemical surfactants. Use of inexpensive substrates can drastically decrease its production cost. Here, twelve solid substrates were screened for the production of Bacillus subtilis SPB1 biosurfactant and the maximum yield was found with millet. A Plackett-Burman design was then used to evaluate the effects of five variables (temperature, moisture, initial pH, inoculum age, and inoculum size). Statistical analyses showed that temperature, inoculum age, and moisture content had significantly positive effect on SPB1 biosurfactant production. Their values were further optimized using a central composite design and a response surface methodology. The optimal conditions of temperature, inoculum age, and moisture content obtained under the conditions of study were 37°C, 14 h, and 88%, respectively. The evaluation of the antimicrobial activity of this compound was carried out against 11 bacteria and 8 fungi. The results demonstrated that this biosurfactant exhibited an important antimicrobial activity against microorganisms with multidrug-resistant profiles. Its activity was very effective against Staphylococcus aureus, Staphylococcus xylosus, Enterococcus faecalis, Klebsiella pneumonia, and so forth.

Enhancement of fructosyltransferase and fructooligosaccharides production by A. oryzae DIA-MF in Solid-State Fermentation using aguamiel as culture medium.

PubMed

Muñiz-Márquez, Diana B; Contreras, Juan C; Rodríguez, Raúl; Mussatto, Solange I; Teixeira, José A; Aguilar, Cristóbal N

2016-08-01

The aim of this work was to improve the production of fructosyltransferase (FTase) by Solid-State Fermentation (SSF) using aguamiel (agave sap) as culture medium and Aspergillus oryzae DIA-MF as producer strain. SSF was carried out evaluating the following parameters: inoculum rate, incubation temperature, initial pH and packing density to determine the most significant factors through Box-Hunter and Hunter design. The significant factors were then further optimized using a Box-Behnken design and response surface methodology. The maximum FTase activity (1347U/L) was obtained at 32°C, using packing density of 0.7g/cm(3). Inoculum rate and initial pH had no significant influence on the response. FOS synthesis applying the enzyme produced by A. oryzae DIA-MF was also studied using aguamiel as substrate. Copyright © 2016 Elsevier Ltd. All rights reserved.

A Laboratory Assessment of Factors That Affect Bacterial Adhesion to Contact Lenses

PubMed Central

Dutta, Debarun; Willcox, Mark DP

2013-01-01

Adhesion of pathogenic microbes, particularly bacteria, to contact lenses is implicated in contact lens related microbial adverse events. Various in vitro conditions such as type of bacteria, the size of initial inoculum, contact lens material, nutritional content of media, and incubation period can influence bacterial adhesion to contact lenses and the current study investigated the effect of these conditions on bacterial adhesion to contact lenses. There was no significant difference in numbers of bacteria that adhered to hydrogel etafilcon A or silicone hydrogel senofilcon A contact lenses. Pseudomonas aeruginosa adhered in higher numbers compared to Staphylococcus aureus. Within a genera/species, adhesion of different bacterial strains did not differ appreciably. The size of initial inoculum, nutritional content of media, and incubation period played significant roles in bacterial adhesion to lenses. A set of in vitro assay conditions to help standardize adhesion between studies have been recommended. PMID:24833224

Evaluation and optimization of ethanol production from carob pod extract by Zymomonas mobilis using response surface methodology.

PubMed

Vaheed, Hossein; Shojaosadati, Seyed Abbas; Galip, Hasan

2011-01-01

In this research, ethanol production from carob pod extract (extract) using Zymomonas mobilis with medium optimized by Plackett-Burman (P-B) and response surface methodologies (RSM) was studied. Z. mobilis was recognized as useful for ethanol production from carob pod extract. The effects of initial concentrations of sugar, peptone, and yeast extract as well as agitation rate (rpm), pH, and culture time in nonhydrolyzed carob pod extract were investigated. Significantly affecting variables (P = 0.05) in the model obtained from RSM studies were: weights of bacterial inoculum, initial sugar, peptone, and yeast extract. Acid hydrolysis was useful to complete conversion of sugars to glucose and fructose. Nonhydrolyzed extract showed higher ethanol yield and residual sugar compared with hydrolyzed extract. Ethanol produced (g g(-1) initial sugar, as the response) was not significantly different (P = 0.05) when Z. mobilis performance was compared in hydrolyzed and nonhydrolyzed extract. The maximum ethanol of 0.34 ± 0.02 g g(-1) initial sugar was obtained at 30°C, initial pH 5.2, and 80 rpm, using concentrations (g per 50 mL culture media) of: inoculum bacterial dry weight, 0.017; initial sugar, 5.78; peptone, 0.43; yeast extract, 0.43; and culture time of 36 h.

Availability of ectomycorrhizal fungi to black spruce above the present treeline in Eastern Labrador.

PubMed

Reithmeier, Laura; Kernaghan, Gavin

2013-01-01

Ectomycorrhizal fungi (ECMF) are an important biotic factor in the survival of conifer seedlings under stressful conditions and therefore have the potential to facilitate conifer establishment into alpine and tundra habitats. In order to assess patterns of ectomycorrhizal availability and community structure above treeline, we conducted soil bioassays in which Picea mariana (black spruce) seedlings were grown in field-collected soils under controlled conditions. Soils were collected from distinct alpine habitats, each dominated by a different ectomycorrhizal host shrub: Betula glandulosa, Arctostaphylos alpina or Salix herbacaea. Within each habitat, half of the soils collected contained roots of ectomycorrhizal shrubs (host (+)) and the other half were free of host plants (host(-)). Forest and glacial moraine soils were also included for comparison. Fungi forming ectomycorrhizae during the bioassays were identified by DNA sequencing. Our results indicate that ECMF capable of colonizing black spruce are widespread above the current tree line in Eastern Labrador and that the level of available inoculum has a significant influence on the growth of seedlings under controlled conditions. Many of the host(-) soils possessed appreciable levels of ectomycorrhizal inoculum, likely in the form of spore banks. Inoculum levels in these soils may be influenced by spore production from neighboring soils where ectomycorrhizal shrubs are present. Under predicted temperature increases, ectomycorrhizal inoculum in soils with host shrubs as well as in nearby soils without host shrubs have the potential to facilitate conifer establishment above the present tree line.

Availability of Ectomycorrhizal Fungi to Black Spruce above the Present Treeline in Eastern Labrador

PubMed Central

Reithmeier, Laura; Kernaghan, Gavin

2013-01-01

Ectomycorrhizal fungi (ECMF) are an important biotic factor in the survival of conifer seedlings under stressful conditions and therefore have the potential to facilitate conifer establishment into alpine and tundra habitats. In order to assess patterns of ectomycorrhizal availability and community structure above treeline, we conducted soil bioassays in which Picea mariana (black spruce) seedlings were grown in field-collected soils under controlled conditions. Soils were collected from distinct alpine habitats, each dominated by a different ectomycorrhizal host shrub: Betula glandulosa, Arctostaphylos alpina or Salix herbacaea. Within each habitat, half of the soils collected contained roots of ectomycorrhizal shrubs (host+) and the other half were free of host plants (host−). Forest and glacial moraine soils were also included for comparison. Fungi forming ectomycorrhizae during the bioassays were identified by DNA sequencing. Our results indicate that ECMF capable of colonizing black spruce are widespread above the current tree line in Eastern Labrador and that the level of available inoculum has a significant influence on the growth of seedlings under controlled conditions. Many of the host− soils possessed appreciable levels of ectomycorrhizal inoculum, likely in the form of spore banks. Inoculum levels in these soils may be influenced by spore production from neighboring soils where ectomycorrhizal shrubs are present. Under predicted temperature increases, ectomycorrhizal inoculum in soils with host shrubs as well as in nearby soils without host shrubs have the potential to facilitate conifer establishment above the present tree line. PMID:24204858

Influence of External Nitrogen on Nitrogenase Enzyme Activity and Auxin Production in Herbaspirillum seropedicae (Z78).

PubMed

Yin, Tan Tzy; Pin, Ui Li; Ghazali, Amir Hamzah Ahmad

2015-04-01

The production of nitrogenase enzyme and auxins by free living diazotrophs has the potential to influence the growth of host plants. In this study, diazotrophs were grown in the presence of various concentrations of nitogen (N) to determine the optimal concentration of N for microbial growth stimulation, promotion of gaseous N (N2) fixation, and phytohormone production. Therefore, we investigate whether different levels of N supplied to Herbaspirillum seropedicae (Z78) have significant effects on nitrogenase activity and auxin production. The highest nitrogenase activity and the lowest auxin production of H. seropedicae (Z78) were both recorded at 0 gL(-1) of NH4Cl. Higher levels of external N caused a significant decrease in the nitrogenase activity and an increased production of auxins. In a subsequent test, two different inoculum sizes of Z78 (10(6) and 10(12) cfu/ml) were used to study the effect of different percentages of acetylene on nitrogenase activity of the inoculum via the acetylene reduction assay (ARA). The results showed that the optimal amount of acetylene required for nitrogenase enzyme activity was 5% for the 10(6) cfu/ml inoculum, whereas the higher inoculum size (10(12) cfu/ml) required at least 10% of acetylene for optimal nitrogenase activity. These findings provide a clearer understanding of the effects of N levels on diazotrophic nitrogenase activity and auxin production, which are important factors influencing plant growth.

Influence of External Nitrogen on Nitrogenase Enzyme Activity and Auxin Production in Herbaspirillum seropedicae (Z78)

PubMed Central

Yin, Tan Tzy; Pin, Ui Li; Ghazali, Amir Hamzah Ahmad

2015-01-01

The production of nitrogenase enzyme and auxins by free living diazotrophs has the potential to influence the growth of host plants. In this study, diazotrophs were grown in the presence of various concentrations of nitogen (N) to determine the optimal concentration of N for microbial growth stimulation, promotion of gaseous N (N2) fixation, and phytohormone production. Therefore, we investigate whether different levels of N supplied to Herbaspirillum seropedicae (Z78) have significant effects on nitrogenase activity and auxin production. The highest nitrogenase activity and the lowest auxin production of H. seropedicae (Z78) were both recorded at 0 gL−1 of NH4Cl. Higher levels of external N caused a significant decrease in the nitrogenase activity and an increased production of auxins. In a subsequent test, two different inoculum sizes of Z78 (106 and 1012 cfu/ml) were used to study the effect of different percentages of acetylene on nitrogenase activity of the inoculum via the acetylene reduction assay (ARA). The results showed that the optimal amount of acetylene required for nitrogenase enzyme activity was 5% for the 106 cfu/ml inoculum, whereas the higher inoculum size (1012 cfu/ml) required at least 10% of acetylene for optimal nitrogenase activity. These findings provide a clearer understanding of the effects of N levels on diazotrophic nitrogenase activity and auxin production, which are important factors influencing plant growth. PMID:26868594

Short- and Long-Term Clinical Outcomes in Rhesus Monkeys Inoculated with a Highly Pathogenic Chimeric Simian/Human Immunodeficiency Virus

PubMed Central

Endo, Yasuyuki; Igarashi, Tatsuhiko; Nishimura, Yoshiaki; Buckler, Charles; Buckler-White, Alicia; Plishka, Ronald; Dimitrov, Dimiter S.; Martin, Malcolm A.

2000-01-01

A highly pathogenic simian/human immunodeficiency virus (SHIV), SHIVDH12R, isolated from a rhesus macaque that had been treated with anti-human CD8 monoclonal antibody at the time of primary infection with the nonpathogenic, molecularly cloned SHIVDH12, induced marked and rapid CD4+ T cell loss in all rhesus macaques intravenously inoculated with 1.0 50% tissue culture infective dose (TCID50) to 4.1 × 105 TCID50s of virus. Animals inoculated with 650 TCID50s of SHIVDH12R or more experienced irreversible CD4+ T lymphocyte depletion and developed clinical disease requiring euthanasia between weeks 12 and 23 postinfection. In contrast, the CD4+ T-cell numbers in four of five monkeys receiving 25 TCID50s of SHIVDH12R or less stabilized at low levels, and these surviving animals produced antibodies capable of neutralizing SHIVDH12R. In the fifth monkey, no recovery from the CD4+ T cell decline occurred, and the animal had to be euthanized. Viral RNA levels, subsequent to the initial peak of infection but not at peak viremia, correlated with the virus inoculum size and the eventual clinical course. Both initial infection rate constants, k, and decay constants, d, were determined, but only the latter were statistically correlated to clinical outcome. The attenuating effects of reduced inoculum size were also observed when virus was inoculated by the mucosal route. Because the uncloned SHIVDH12R stock possessed the genetic properties of a lentivirus quasispecies, we were able to assess the evolution of the input virus swarm in animals surviving the acute infection by monitoring the emergence of neutralization escape viral variants. PMID:10888632

Influence of inocula with prior hydrocarbon exposure on biodegradation rates of diesel, synthetic diesel, and fish-biodiesel in soil.

PubMed

Horel, Agota; Schiewer, Silke

2014-08-01

To achieve effective bioremediation within short warm seasons of cold climates, microbial adaptation periods to the contaminant should be brief. The current study investigated growth phases for soil spiked with diesel, Syntroleum, or fish biodiesel, using microbial inocula adapted to the specific substrates. For modeling hydrocarbon degradation, multi-phase first order kinetics was assumed, comparing linear regression with nonlinear parameter optimization of rate constants and phase durations. Lag phase periods of 5 to >28d were followed by short and intense exponential growth phases with high rate constants (e.g. from kFish=0.0013±0.0002 to kSyntr=0.015±0.001d(-1)). Hydrocarbon mineralization was highest for Syntroleum contamination, where up to three times higher cumulative CO2 production was achieved than for diesel fuel, with fish biodiesel showing initially the slowest degradation. The amount of hydrocarbons recovered from the soil by GC-MS decreased in the order fish biodiesel>diesel>Syntroleum. During initial weeks, biodegradation was higher for microbial inocula adapted to a specific fuel type, whereby the main effect of the inoculum was to shorten the lag phase duration; however, the inoculum's importance diminished after daily respiration peaked. In conclusion, addition of an inoculum to increase biodegradation rates was not necessary. Copyright © 2014 Elsevier Ltd. All rights reserved.

Impact of relative humidity, inoculum carrier and size, and native microbiota on Salmonella ser. Typhimurium survival in baby lettuce.

PubMed

López-Gálvez, Francisco; Gil, Maria Isabel; Allende, Ana

2018-04-01

The effects of relative humidity (RH), fluctuating climate conditions, inoculum size and carrier on the survival of Salmonella enterica serovar Typhimurium on baby lettuce in environmental test chambers were studied. Buffered peptone water (BPW), distilled water (DW), and irrigation water (IW) were compared as inoculum carriers. Additionally, survival of Salmonella in suspensions prepared using filtered and unfiltered IW was assessed. Salmonella Typhimurium survived better on baby lettuce plants at high RH independently of the inoculum size. When lettuce plants were grown under fluctuating environmental conditions, Salmonella survival was similar under both RH conditions. Regarding the inoculum carrier, the inoculated microorganism survived better on lettuce plants when BPW was used as carrier both at high and low RH. Survival rate of Salmonella in IW was affected by the presence of native microbiota. Native microbiota present in IW did not affect survival of Salmonella or the levels of mesophilic bacteria on the baby lettuce leaves. The information obtained in the present study contributes to the knowledge on the effect of environmental conditions on pathogenic bacteria survival on growing edible plants. These results are useful when selecting the methodology to carry out experimental studies on the survival of microbial pathogens under different pre-harvest conditions. Copyright © 2017 Elsevier Ltd. All rights reserved.

Survival of a native toxigenic isolate of Listeria monocytogenes CFR 1302 during storage of milk-based foods can be a potential cause of health risk.

PubMed

Jayanth, Hampapura S; Varadaraj, Mandyam C

2017-07-01

The ability of a native toxigenic culture of Listeria monocytogenes CFR 1302 to survive and elaborate associated toxigenic trait in ice cream and mango pulp-based lactic fermented milk was studied. The culture of L. monocytogenes inoculated at two initial levels of 4.6 and 5.6 log 10  CFU/ml almost remained unaltered during storage of the food products. However, in both the milk-based products, a marginal increase in viable population was observed during 2-4 d of storage as against the initial inoculum levels. The toxigenic trait, listeriolysin "O" was detected by PCR based on species-specific hlyA primers in the two products without any step of enrichment. The positive amplification in PCR was evidenced with initial population levels of 6.3, 7.3, and 8.3 log 10  CFU/ml of the respective products. In culture broth, PCR detection was positive with the lowest level of 2.3 log 10  CFU/ml. The established pathogenic strain of L. monocytogenes Scott A used as a reference culture revealed almost the same behavior to that of native culture in the food products. The findings of present study bring into focus that, irrespective of low storage temperatures, there exists the potential health hazard associated with foods initially contaminated with risk population levels of L. monocytogenes.

Simultaneous saccharification and fermentation of Agave tequilana fructans by Kluyveromyces marxianus yeasts for bioethanol and tequila production.

PubMed

Flores, Jose-Axel; Gschaedler, Anne; Amaya-Delgado, Lorena; Herrera-López, Enrique J; Arellano, Melchor; Arrizon, Javier

2013-10-01

Agave tequilana fructans (ATF) constitute a substrate for bioethanol and tequila industries. As Kluyveromyces marxianus produces specific fructanases for ATF hydrolysis, as well as ethanol, it can perform simultaneous saccharification and fermentation. In this work, fifteen K. marxianus yeasts were evaluated to develop inoculums with fructanase activity on ATF. These inoculums were added to an ATF medium for simultaneous saccharification and fermentation. All the yeasts, showed exo-fructanhydrolase activity with different substrate specificities. The yeast with highest fructanase activity in the inoculums showed the lowest ethanol production level (20 g/l). Five K. marxianus strains were the most suitable for the simultaneous saccharification and fermentation of ATF. The volatile compounds composition was evaluated at the end of fermentation, and a high diversity was observed between yeasts, nevertheless all of them produced high levels of isobutyl alcohol. The simultaneous saccharification and fermentation of ATF with K. marxianus strains has potential for industrial application. Copyright © 2013 Elsevier Ltd. All rights reserved.

Evidence that Blueberry Floral Extracts Influence Secondary Conidiation and Appressorial Formation of Colletotrichum fioriniae.

PubMed

Waller, Timothy J; Vaiciunas, Jennifer; Constantelos, Christine; Oudemans, Peter V

2018-05-01

Blueberry anthracnose, caused by Colletotrichum fioriniae, is a pre- and postharvest disease of cultivated highbush blueberry (Vaccinium corymbosum). During disease development, the pathogen undergoes several lifestyle changes during host colonization, including epiphytic, quiescent, and necrotrophic phases. It is not clear, however, what if any host signals alter the pattern of colonization during the initial epiphytic phase and infection. This research investigated the role of blueberry floral extracts (FE) on fungal development. Results show that FE significantly increased both the quantity and rate of secondary conidiation and appressorial formation in vitro, suggesting that floral components could decrease the minimum time required for infection. Activity of FE was readily detected in water collected from field samples, where secondary conidiation and appressorial formation decreased as rainwater collections were further removed from flowers. A comparison of FE from four blueberry cultivars with different levels of field susceptibility revealed that appressorial formation but not secondary conidiation significantly increased with the FE from susceptible cultivars versus resistant cultivars. Inoculum supplemented with FE produced higher levels of disease on ripe blueberry fruit as compared with inoculum with water only. Flowers from other ericaceous species were found to also induce secondary conidiation and appressorial formation of C. fioriniae. This research provides strong evidence that flowers can contribute substantially to the infection process of C. fioriniae, signifying the importance of the bloom period for developing effective disease management strategies.

Production of prodigiosin and chitinases by tropical Serratia marcescens strains with potential to control plant pathogens.

PubMed

Gutiérrez-Román, Martha Ingrid; Holguín-Meléndez, Francisco; Bello-Mendoza, Ricardo; Guillén-Navarro, Karina; Dunn, Michael F; Huerta-Palacios, Graciela

2012-01-01

The potential of three Serratia marcescens strains (CFFSUR-B2, CFFSUR-B3 and CFFSUR-B4) isolated from tropical regions in Mexico to inhibit the mycelial growth and conidial germination of Colletotrichum gloeosporioides, causal agent of fruit anthracnose, was evaluated. The ability of these strains to produce prodigiosin and chitinases when cultivated in oil seed-based media (peanut, sesame, soybean and castor bean) and in Luria-Bertani medium was determined. All of the strains exhibited similar fungal antagonistic activities and inhibited myceliar growth by more than 40% while inhibiting conidial germination by 81-89% (P = 0.01). The highest level of prodigiosin (40 μg/ml) was produced in the peanut-based medium while growth in soybean-based medium allowed the highest production of chitinases (56 units/ml), independent of the strain used. Strain CFFSUR-B2 grown in peanut medium was used to evaluate the effect of inoculum density and initial pH on metabolite production. The amount of prodigiosin produced increased with greater inoculum densities, with an initial density of 1 × 10(12) resulting in the highest production (60 μg/ml). Prodigiosin production was not affected by pH. The strains studied have the advantage of being adapted to tropical climates and are able to produce chitinases in the absence of chitin induction in vitro. These characteristics suggest their potential as biocontrol agents for fungal pathogens in tropical regions of the world.

'Prion-like' propagation of the synucleinopathy of M83 transgenic mice depends on the mouse genotype and type of inoculum.

PubMed

Sargent, Dorian; Verchère, Jérémy; Lazizzera, Corinne; Gaillard, Damien; Lakhdar, Latifa; Streichenberger, Nathalie; Morignat, Eric; Bétemps, Dominique; Baron, Thierry

2017-10-01

The M83 transgenic mouse is a model of human synucleinopathies that develops severe motor impairment correlated with accumulation of the pathological Ser129-phosphorylated α-synuclein (α-syn P ) in the brain and spinal cord. M83 disease can be accelerated by intracerebral inoculation of brain extracts from sick M83 mice. This has also recently been described using peripheral routes, injecting recombinant preformed α-syn fibrils into the muscle or the peritoneum. Here, we inoculated homozygous and/or hemizygous M83 neonates via the intraperitoneal and/or intracerebral routes with two different brain extracts: one from sick M83 mice inoculated with brain extract from other sick M83 mice, and the other derived from a human multiple system atrophy source passaged in M83 mice. Detection of α-syn P using ELISA and western blot confirmed the disease in mice. The distribution of α-syn P in the central nervous system was similar, independently of the inoculum or inoculation route, consistent with previous studies describing M83 disease. ELISA tests revealed higher levels of α-syn P in homozygous than in hemizygous sick M83 mice, at least after IC inoculation. Interestingly, the immunoreactivity of α-syn P detected by ELISA was significantly lower in M83 mice inoculated with the multiple system atrophy inoculum than in M83 mice inoculated with the M83 inoculum, at the first two passages. 'Prion-like' propagation of the synucleinopathy up to the clinical disease was accelerated by both intracerebral and intraperitoneal inoculations of brain extracts from sick mice. This acceleration, however, depends on the levels of α-syn expression by the mouse and the type of inoculum. © 2017 International Society for Neurochemistry.

Sabin-to-Mahoney Transition Model of Quasispecies Replication

DOE Office of Scientific and Technical Information (OSTI.GOV)

2009-05-31

Qspp is an agent-based stochastic simulation model of the Poliovirus Sabin-to-Mahoney transition. This code simulates a cell-to-cell model of Poliovirus replication. The model tracks genotypes (virus genomes) as they are replicated in cells, and as the cells burst and release particles into the medium of a culture dish. An inoculum is then taken from the pool of virions and is used to inoculate cells on a new dish. This process repeats. The Sabin genotype comprises the initial inoculum. Nucleotide positions that match the Sabin1 (vaccine strain) and Mahoney (wild type) genotypes, as well as the neurovirulent phenotype (from the literature)more » are enumerated as constants.« less

Development of a robust, versatile, and scalable inoculum train for the production of a DNA vaccine.

PubMed

Okonkowski, J; Kizer-Bentley, L; Listner, K; Robinson, D; Chartrain, M

2005-01-01

For many microbial fermentation processes, the inoculum train can have a substantial impact on process performance in terms of productivity, profitability, and process control. In general, it is understood that a well-characterized and flexible inoculum train is essential for future scale-up and implementation of the process in a pilot plant or manufacturing setting. A fermentation process utilizing E. coli DH5 for the production of plasmid DNA carrying the HIV gag gene for use as a vaccine is currently under development in our laboratory. As part of the development effort, we evaluated inoculum train schemes that incorporate one, two, or three stages. In addition, we investigated the effect of inoculum viable-cell concentrations, either thawed or actively growing, over a wide range (from 2.5 x 10(4) to 1.0 x 10(8) viable cells/mL or approximately 0.001% to 4% of final working volume). The various inoculum trains were evaluated in terms of final plasmid yield, process time, reproducibility, robustness, and feasibility at large scale. The results of these studies show that final plasmid yield remained in the desired range, despite the number of stages or inoculation viable-cell concentrations comprising the inoculum train. On the basis of these observations and because it established a large database, the first part of these investigations supports an exceptional flexibility in the design of scalable inoculum trains for this DNA vaccine process. This work also highlighted that a slightly higher level of process reproducibility, as measured by the time for the culture to reach mid-exponential growth, was observed when using actively growing versus frozen cells. It also demonstrated the existence of a viable-cell concentration threshold for the one-stage process, since we observed that inoculation of the production stage with very low amounts of viable cells from a frozen source could lead to increased process sensitivity to external factors such as variation in the quality of the raw materials used in the medium formulation. However, our analysis indicates that, despite this slight disadvantage, a one-stage inoculum train was a viable option in many situations, especially if the inoculation viable-cell concentration was kept above 4.8 x 10(6) viable cells/mL. Because it leads to a reduction in process steps and eliminates some capital investments (i.e., inoculum fermenter), when feasible a one-stage process configuration will positively impact process economics.

Efficacy of Daptomycin Monotherapy and In Combination with β-lactams for Daptomycin-Susceptible Enterococcus faecium Harboring LiaSR Substitutions: Influence of The Inoculum Effect.

PubMed

Kebriaei, Razieh; Rice, Seth A; Singh, Kavindra V; Stamper, Kyle C; Dinh, An Q; Rios, Rafael; Diaz, Lorena; Murray, Barbara E; Munita, Jose M; Tran, Truc T; Arias, Cesar A; Rybak, Michael J

2018-05-14

Enterococcus faecium that harbor LiaFSR substitutions but are phenotypically susceptible to daptomycin (DAP) by current breakpoints are problematic since predisposition to resistance may lead to therapeutic failure. Using a simulated endocardial vegetation (SEV) PK/PD model, we investigated DAP regimens (6, 8 and 10 mg/kg/day) as monotherapy and in combination with ampicillin (AMP), ceftaroline (CPT) or ertapenem (ERT) against E. faecium HOU503, a DAP-susceptible strain that harbors common LiaS and LiaR substitutions found in clinical isolates (T120S and W73C, respectively). Of interest, the efficacy of DAP monotherapy, at any dose regimen, was dependent on the size of the inoculum. At an inoculum of ∼10 9 CFU/g, DAP doses of 6-8 mg/kg/d were not effective and led to significant regrowth with emergence of resistant derivatives. In contrast, at an inoculum of ∼10 7 , marked reductions in bacterial counts were observed with DAP 6 mg/kg/d with no resistance. The inoculum effect was confirmed in a rat model using humanized DAP exposures. Combinations of DAP with AMP, CPT or ERT demonstrated enhanced eradication and reduced potential for resistance allowing for de-escalation of the DAP dose. Persistence of the LiaRS substitutions were identified in DAP-resistant isolates recovered from the SEV model and in DAP-resistant derivatives of an initially DAP-susceptible clinical isolate of E. faecium (HOU668) harboring LiaSR substitutions and recovered from a patient with a recurrent bloodstream infection. Our results provide novel data for the use of DAP monotherapy and combinations for recalcitrant E. faecium infections and paves the way for testing these approaches in humans. Copyright © 2018 American Society for Microbiology.

Investigation of Antimicrobial Activity and Statistical Optimization of Bacillus subtilis SPB1 Biosurfactant Production in Solid-State Fermentation

PubMed Central

Ghribi, Dhouha; Abdelkefi-Mesrati, Lobna; Mnif, Ines; Kammoun, Radhouan; Ayadi, Imen; Saadaoui, Imen; Maktouf, Sameh; Chaabouni-Ellouze, Semia

2012-01-01

During the last years, several applications of biosurfactants with medical purposes have been reported. Biosurfactants are considered relevant molecules for applications in combating many diseases. However, their use is currently extremely limited due to their high cost in relation to that of chemical surfactants. Use of inexpensive substrates can drastically decrease its production cost. Here, twelve solid substrates were screened for the production of Bacillus subtilis SPB1 biosurfactant and the maximum yield was found with millet. A Plackett-Burman design was then used to evaluate the effects of five variables (temperature, moisture, initial pH, inoculum age, and inoculum size). Statistical analyses showed that temperature, inoculum age, and moisture content had significantly positive effect on SPB1 biosurfactant production. Their values were further optimized using a central composite design and a response surface methodology. The optimal conditions of temperature, inoculum age, and moisture content obtained under the conditions of study were 37°C, 14 h, and 88%, respectively. The evaluation of the antimicrobial activity of this compound was carried out against 11 bacteria and 8 fungi. The results demonstrated that this biosurfactant exhibited an important antimicrobial activity against microorganisms with multidrug-resistant profiles. Its activity was very effective against Staphylococcus aureus, Staphylococcus xylosus, Enterococcus faecalis, Klebsiella pneumonia, and so forth. PMID:22536017

Effect of white mustard cover crop residue, soil chemical fumigation and Trichoderma spp. root treatment on black-foot disease control in grapevine.

PubMed

Berlanas, Carmen; Andrés-Sodupe, Marcos; López-Manzanares, Beatriz; Maldonado-González, María Mercedes; Gramaje, David

2018-05-20

Black-foot disease is one of the main soilborne fungal diseases affecting grapevine production worldwide. Two field experiments were established to evaluate the effect of white mustard cover crop residue amendment and chemical fumigation with propamocarb + fosetyl-Al combined with Trichoderma spp. root treatment on the viability of black-foot inoculum in soil and fungal infection in grafted plants and grapevine seedlings used as bait plants. A total of 876 black-foot pathogens isolates were collected from grafted plants and grapevine seedlings used as bait plants in both fields. White mustard biofumigation reduced inoculum of Dactylonectria torresensis and the incidence and severity of black-foot of grapevine, but no added benefit was obtained when biofumigation was used with Trichoderma spp. root treatments. The effect of white mustard residues and chemical fumigation on populations of D. torresensis propagules in soil was inconsistent, possibly due to varying pretreatment inoculum levels. Biofumigation with white mustard plants had potential for improving control of black-foot disease in grapevines. This control strategy can reduce soil inoculum levels and protect young plants from infection, providing grape growers and nursery propagators with more tools for developing integrated and sustainable control systems. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Influence of nanohydroxyapatite surface properties on Staphylococcus epidermidis biofilm formation.

PubMed

Barros, J; Grenho, L; Manuel, C M; Ferreira, C; Melo, L; Nunes, O C; Monteiro, F J; Ferraz, M P

2014-05-01

Nanohydroxyapatite (nanoHA), due to its chemical properties, has appeared as an exceptionally promising bioceramic to be used as bone regeneration material. Staphylococcus epidermidis have emerged as major nosocomial pathogens associated with infections of implanted medical devices. In this work, the purpose was to study the influence of the nanoHA surface characteristics on S. epidermidis RP62A biofilm formation. Therefore, two different initial inoculum concentrations (Ci) were used in order to check if these would affect the biofilm formed on the nanoHA surfaces. Biofilm formation was followed by the enumeration of cultivable cells and by scanning electron microscopy. Surface topography, contact angle, total surface area and porosimetry of the biomaterials were studied and correlated with the biofilm data. The surface of nanoHA sintered at 830 (nanoHA830) showed to be more resistant to S. epidermidis attachment and accumulation than that of nanoHA sintered at 1000 (nanoHA1000). The biofilm formed on nanoHA830 presented differences in terms of structure, surface coverage and EPS production when compared to the one formed on nanoHA1000 surface. It was observed that topography and surface area of nanoHA surfaces had influence on the bacterial attachment and accumulation. Ci influenced bacteria attachment and accumulation on nanoHA surfaces over time. The choice of the initial inoculum concentration was relevant proving to have an effect on the extent of adherence thus being a critical point for human health if these materials are used in implantable devices. This study showed that the initial inoculum concentration and surface material properties determine the rate of microbial attachment to substrata and consequently are related to biofilm-associated infections in biomaterials.

Biohythane production from marine macroalgae Sargassum sp. coupling dark fermentation and anaerobic digestion.

PubMed

Costa, José C; Oliveira, João V; Pereira, Maria A; Alves, Maria M; Abreu, Angela A

2015-08-01

Potential biohythane production from Sargassum sp. was evaluated in a two stage process. In the first stage, hydrogen dark fermentation was performed by Caldicellulosiruptor saccharolyticus. Sargassum sp. concentrations (VS) of 2.5, 4.9 and 7.4gL(-1) and initial inoculum concentrations (CDW) of 0.04 and 0.09gL(-1) of C. saccharolyticus were used in substrate/inoculum ratios ranging from 28 to 123. The end products from hydrogen production process were subsequently used for biogas production. The highest hydrogen and methane production yields, 91.3±3.3Lkg(-1) and 541±10Lkg(-1), respectively, were achieved with 2.5gL(-1) of Sargassum sp. (VS) and 0.09gL(-1)of inoculum (CDW). The biogas produced contained 14-20% of hydrogen. Potential energy production from Sargassum sp. in two stage process was estimated in 242GJha(-1)yr(-1). A maximum energy supply of 600EJyr(-1) could be obtained from the ocean potential area for macroalgae production. Copyright © 2015 Elsevier Ltd. All rights reserved.

Adaptation of Methanogenic Inocula to Anaerobic Digestion of Maize Silage

PubMed Central

Wojcieszak, Martyna; Pyzik, Adam; Poszytek, Krzysztof; Krawczyk, Pawel S.; Sobczak, Adam; Lipinski, Leszek; Roubinek, Otton; Palige, Jacek; Sklodowska, Aleksandra; Drewniak, Lukasz

2017-01-01

A well-balanced microbial consortium is crucial for efficient biogas production. In turn, one of a major factor that influence on the structure of anaerobic digestion (AD) consortium is a source of microorganisms which are used as an inoculum. This study evaluated the influence of inoculum sources (with various origin) on adaptation of a biogas community and the efficiency of the biomethanization of maize silage. As initial inocula for AD of maize silage the samples from: (i) an agricultural biogas plant (ABP) which utilizes maize silage as a main substrate, (ii) cattle slurry (CS), which contain elevated levels of lignocelluloses materials, and (iii) raw sewage sludge (RSS) with low content of plant origin materials were used. The adaptation of methanogenic consortia was monitored during a series of passages, and the functionality of the adapted consortia was verified through start-up operation of AD in two-stage reactors. During the first stages of the adaptation phase, methanogenic consortia occurred very slowly, and only after several passages did the microbial community adapts to allow production of biogas with high methane content. The ABP consortium revealed highest biogas production in the adaptation and in the start-up process. The biodiversity dynamics monitored during adaptation and start-up process showed that community profile changed in a similar direction in three studied consortia. Native communities were very distinct to each other, while at the end of the Phase II of the start-up process microbial diversity profile was similar in all consortia. All adopted bacterial communities were dominated by representatives of Porphyromonadaceae, Rikenellaceae, Ruminococcaceae, and Synergistaceae. A shift from low acetate-preferring acetoclastic Methanosaetaceae (ABP and RSS) and/or hydrogenotrophic Archaea, e.g., Methanomicrobiaceae (CS) prevailing in the inoculum samples to larger populations of high acetate-preferring acetoclastic Methanosarcinaceae was observed by the end of the experiment. As a result, three independent, functional communities that syntrophically produced methane from acetate (primarily) and H2/CO2, methanol and methylamines were adapted. This study provides new insights into the specific process by which different inocula sampled from typical methanogenic environments that are commonly used to initiate industrial installations gradually adapted to allow biogas production from maize silage. PMID:29033919

Anaerobic digestion of food waste for volatile fatty acids (VFAs) production with different types of inoculum: effect of pH.

PubMed

Wang, Kun; Yin, Jun; Shen, Dongsheng; Li, Na

2014-06-01

Food waste anaerobic fermentation was carried out under acidic conditions using inocula based on aerobic activated sludge (Inoculum AE) or anaerobic activated sludge (Inoculum AN) for volatile fatty acids (VFAs) production. The results showed that food waste hydrolysis increased obviously when Inoculum AN was used relative to Inoculum AE at any pH investigated. Hydrolysis at pH 4.0 and uncontrolled pH was higher than that at other pHs when either inoculum was used. Additionally, VFAs production at pH 6.0 was the highest, regardless of the inoculum used. The optimum VFA yields were 0.482g/gVSSremoval with Inoculum AE and 0.918g/gVSSremoval with Inoculum AN, which were observed after 4d and 20d of fermentation, respectively. VFAs composition analysis showed that butyrate acid was the prevalent acid at pH 6.0, followed by acetate acid and propionic acid. Copyright © 2014 Elsevier Ltd. All rights reserved.

Alcohol-to-acid ratio and substrate concentration affect product structure in chain elongation reactions initiated by unacclimatized inoculum.

PubMed

Liu, Yuhao; Lü, Fan; Shao, Liming; He, Pinjing

2016-10-01

The objective of the study was to investigate whether the ratio of ethanol to acetate affects yield and product structure in chain elongation initiated by unacclimatized mixed cultures. The effect of varying the substrate concentration, while maintaining the same ratio of alcohol to acid, was also investigated. With a high substrate concentration, an alcohol to acid ratio >2:1 provided sufficient electron donor capacity for the chain elongation reaction. With an ethanol to acetate ratio of 3:1 (300mM total carbon), the highest n-caproate concentration (3033±98mg/L) was achieved during the stable phase of the reaction. A lower substrate concentration (150mM total carbon) gave a lower yield of products and led to reduced carbon transformation efficiency compared with other reaction conditions. The use of unacclimatized inoculum in chain elongation can produce significant amounts of odd-carbon-number carboxylates as a result of protein hydrolysis. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effects of superheated steam on Geobacillus stearothermophilus spore viability.

PubMed

Head, D S; Cenkowski, S; Holley, R; Blank, G

2008-04-01

To examine the effect of processing with superheated steam (SS) on Geobacillus stearothermophilus ATCC 10149 spores. Two inoculum levels of spores of G. stearothermophilus were mixed with sterile sand and exposed to SS at 105-175 degrees C. The decimal reduction time (D-value) and the thermal resistance constant (z-value) were calculated. The effect of cooling of spores between periods of exposure to SS was also examined. A mean z-value of 25.4 degrees C was calculated for both inoculum levels for SS processing temperatures between 130 degrees C and 175 degrees C. Spore response to SS treatment depends on inoculum size. SS treatment may be effective for reduction in viability of thermally resistant bacterial spores provided treatments are separated by intermittent cooling periods. There is a need for technologies that require short thermal processing times to eliminate bacterial spores in foods. The SS processing technique has the potential to reduce microbial load and to modify food texture with less energy in comparison to commonly used hot air treatment. This work provides information on the effect of SS processing parameters on the viability of G. stearothermophilus spores.

Enhancing anaerobic digestion of food waste through biochemical methane potential assays at different substrate: inoculum ratios.

PubMed

Hobbs, Shakira R; Landis, Amy E; Rittmann, Bruce E; Young, Michelle N; Parameswaran, Prathap

2018-01-01

Food waste has a high energy potential that can be converted into useful energy in the form of methane via anaerobic digestion. Biochemical Methane Potential assays (BMPs) were conducted to quantify the impacts on methane production of different ratios of food waste. Anaerobic digester sludge (ADS) was used as the inoculum, and BMPs were performed at food waste:inoculum ratios of 0.42, 1.42, and 3.0g chemical oxygen demand/g volatile solids (VS). The 1.42 ratio had the highest CH 4 -COD recovery: 90% of the initial total chemical oxygen demand (TCOD) was from food waste, followed by ratios 0.42 and 3.0 at 69% and 57%, respectively. Addition of food waste above 0.42 caused a lag time for CH 4 production that increased with higher ratios, which highlighted the negative impacts of overloading with food waste. The Gompertz equation was able to represent the results well, and it gave lag times of 0, 3.6 and 30days and maximum methane productions of 370, 910, and 1950mL for ratios 0.42, 1.42 and 3.0, respectively. While ratio 3.0 endured a long lag phase and low VSS destruction, ratio 1.42 achieved satisfactory results for all performance criteria. These results provide practical guidance on food-waste-to-inoculum ratios that can lead to optimizing methanogenic yield. Copyright © 2017 Elsevier Ltd. All rights reserved.

Proteolysis in tempeh-type products obtained with Rhizopus and Aspergillus strains from grass pea (Lathyrus sativus) seeds.

PubMed

Starzyńska-Janiszewska, Anna; Stodolak, Bożena; Wikiera, Agnieszka

2015-01-01

Tempeh is a food product obtained from legumes by means of solid-state fermentation with Rhizopus sp. Our previous research proved that mixed-culture inoculum may also be successfully applied. The objective of present research was to study the proteolytic activity of R. microsporus var. chinensis and A. oryzae during tempeh-type fermentation of grass pea seeds, and the effect of inoculum composition on the protein level and in vitro protein bioavailability in products. Fermentation substrate were soaked and cooked grass pea seeds. Material was mixed with single- or mixed-culture inoculum, and incubated in perforated plastic bags at 30°C for 32 hrs. In the products, the proteolytic activity (pH 3, 5 and 7), glucosamine, total protein and free amino acids levels, as well as protein in vitro bioavailability and degree of protein hydrolysis were obtained. The significant correlation was found between glucosamine content and proteolytic activity in grass pea seeds fermented with Rhizopus or Aspergillus. The activities of Rhizopus proteases were higher than Aspergillus ones, which corresponded with the degree of seed protein hydrolysis. Both strains showed the highest activity of protease at pH 3. Tempeh made with pure culture of Rhizopus had 37% protein of 69% in-vitro bioavailability. Mixed-culture fermentation improved nutritional parameters of products only when the dose of Aspergillus spores in the inoculum was equal and lower than that of Rhizopus. This process resulted in higher in-vitro bioavailability of protein, slightly more efficient protein hydrolysis and higher level of free amino acids, as compared to standard tempeh. The activity of A. oryzae in tempeh-type fermentation is beneficial as long as it does not dominate the activity and/or growth of Rhizopus strain.

Infection, Reproduction Potential, and Root Galling by Root-knot Nematode Species and Concomitant Populations on Peanut and Tobacco

PubMed Central

Hirunsalee, Anan; Barker, K. R.; Beute, M. K.

1995-01-01

Single populations of Meloidogyne arenaria races 1 (MA1) and 2 (MA2) and M. hapla (MH), and mixed populations of MA1 + MA2 and MA1 + MH with four inoculum levels of eggs were tested on peanut cv. 'Florigiant' and M. incognita-resistant tobacco cv. 'McNair 373' in a greenhouse experiment. Root infection, female development, and reproduction of MA2 on peanut and MA1 on resistant tobacco were limited at 2 and 6 weeks. MA1, MH, and MA1 + MH on peanut had similar root infection (total parasitic forms per root unit) at both 2 and 6 weeks, and similar female development and reproduction potentials at 6 weeks. MA2 tended to depress root infection, female development, and reproduction of MA1 on peanut. MH had little effect on MA1 on this crop. On tobacco, MA2 population had greater incidence of root infection than did MH at 2 weeks. The two nematode species had similar development in roots at 6 weeks. All of these processes were restricted when either MA2 or MH was present together with MA1. As initial inoculum level of parasitically fit populations increased, relative infection ratio on both peanut and tobacco, and reproduction factor on peanut decreased. Populations that had high infection incidence and reproduction rates induced greater root galling than did other populations. Root galling was suppressed in the presence of antagonistic response between nematode populations. PMID:19277277

An attempt to model the probability of growth and aflatoxin B1 production of Aspergillus flavus under non-isothermal conditions in pistachio nuts.

PubMed

Aldars-García, Laila; Ramos, Antonio J; Sanchis, Vicente; Marín, Sonia

2015-10-01

Human exposure to aflatoxins in foods is of great concern. The aim of this work was to use predictive mycology as a strategy to mitigate the aflatoxin burden in pistachio nuts postharvest. The probability of growth and aflatoxin B1 (AFB1) production of aflatoxigenic Aspergillus flavus, isolated from pistachio nuts, under static and non-isothermal conditions was studied. Four theoretical temperature scenarios, including temperature levels observed in pistachio nuts during shipping and storage, were used. Two types of inoculum were included: a cocktail of 25 A. flavus isolates and a single isolate inoculum. Initial water activity was adjusted to 0.87. Logistic models, with temperature and time as explanatory variables, were fitted to the probability of growth and AFB1 production under a constant temperature. Subsequently, they were used to predict probabilities under non-isothermal scenarios, with levels of concordance from 90 to 100% in most of the cases. Furthermore, the presence of AFB1 in pistachio nuts could be correctly predicted in 70-81 % of the cases from a growth model developed in pistachio nuts, and in 67-81% of the cases from an AFB1 model developed in pistachio agar. The information obtained in the present work could be used by producers and processors to predict the time for AFB1 production by A. flavus on pistachio nuts during transport and storage. Copyright © 2015 Elsevier Ltd. All rights reserved.

Evaluation of Proposed Dredged Material Disposal Alternatives for New York/New Jersey Harbor. Phase 1

DTIC Science & Technology

1988-08-01

following initial incubation of the inoculum in lactose broth. The presence of Vibrio parahemolyticus was determined using trypticase citrate 0 bile salts...SaZmonella (enteritis), SalmonelZa typhosa (typhoid fever), ShigeZla (dysentery), and Vibrio cholerae (cholera). The organisms causing these diseases do not

Chitosan production by psychrotolerant Rhizopus oryzae in non-sterile open fermentation conditions.

PubMed

Tasar, Ozden Canli; Erdal, Serkan; Taskin, Mesut

2016-08-01

A new chitosan producing fungus was locally isolated from soil samples collected around Erzurum, Turkey and identified as Rhizopus oryzae PAS 17 (GenBank accession number KU318422.1). Cultivation in low cost non-sterile conditions was achieved by exploiting its ability to grow at low temperature and pH, thus, undesired microbial contamination could be eliminated when appropriate culture conditions (incubation temperature as 15°C and initial pH of the medium as 4.5) were selected. Medium composition and culture conditions were optimized using Taguchi orthogonal array (OA) design of experiment (DOE). An OA layout of L16 (4(5)) was constructed with five most influensive factors at four levels on chitosan production like, carbon source (molasses), metal ion (Mg(2+)), inoculum amount, agitation speed and incubation time. The optimal combinations of factors (molasses, 70ml/l; MgSO4·7H2O, 0.5g/l; inoculum, 6.7×10(6) spores/disc; agitation speed, 150rpm and incubation time, 8days) obtained from the proposed DOE methodology was further validated by analysis of variance (ANOVA) test and the results revealed the increment of chitosan and biomass yields of 14.45 and 8.58 folds from its unoptimized condition, respectively. Copyright © 2016 Elsevier B.V. All rights reserved.

Internalization and dissemination of human norovirus and Tulane virus in fresh produce is plant dependent.

PubMed

Yang, Zhihong; Chambers, Heather; DiCaprio, Erin; Gao, Gary; Li, Jianrong

2018-02-01

Human norovirus (NoV) is a leading cause of fresh produce associated outbreaks. Previous research indicates that the roots of growing leafy greens and berries internalize human NoV. However the effect of plant type and inoculum level on internalization rates has not been directly compared. In this study we compared the internalization and dissemination rates of human NoV and its surrogate, Tulane virus (TV) in green onion, radishes, and Romaine lettuce. We also evaluated the effect inoculum level and plant growth matrix on the rate of viral internalization. In the hydroponic growth system, we detected internalization and dissemination of human NoV RNA in green onions. In hydroponically growing green onions inoculated with high titer TV, we found higher rates of internalization and dissemination compared to green onions inoculated with low titer TV. In soil growth systems, no infectious TV was detected in either green onion or radishes. However, in Romaine lettuce plants grown in soil approximately 4 log 10  PFU/g was recovered from all tissues on day 14 p.i. Overall, we found that the type of plant, growth matrix, and the inoculum level influences the internalization and dissemination of human NoV and TV. Copyright © 2017 Elsevier Ltd. All rights reserved.

The growth of Treponema hyodysenteriae and other porcine intestinal spirochaetes in a liquid medium.

PubMed

Lemcke, R M; Bew, J; Burrows, M R; Lysons, R J

1979-05-01

A new simple method for the preparation of a liquid medium containing rabbit serum for the propagation of Treponema hyodysenteriae and other porcine intestinal spirochaetes is described. The medium, when dispensed in shallow layers and sealed under 10 per cent CO2 in nitrogen, had a redox potential not greater than -125mV and an initial pH of about 6.9 when buffered with bicarbonate. Growth of T hyodysenteriae developed more rapidly and viable counts reached higher levels at 42 degrees C than at 37 degrees C. Viable counts increased at least 10,000-fold after two to five days' incubation, depending on the temperature. Growth could be initiated from small inocula that failed to produce colonies on blood agar. Using a 1 per cent inoculum, the medium supported the growth of two strains of T hyodysenteriae through 10 serial passages.

Modelling and predicting the simultaneous growth of Escherichia coli and lactic acid bacteria in milk.

PubMed

Ačai, P; Valík, L'; Medved'ová, A; Rosskopf, F

2016-09-01

Modelling and predicting the simultaneous competitive growth of Escherichia coli and starter culture of lactic acid bacteria (Fresco 1010, Chr. Hansen, Hørsholm, Denmark) was studied in milk at different temperatures and Fresco inoculum concentrations. The lactic acid bacteria (LAB) were able to induce an early stationary state in E. coli The developed model described and tested the growth inhibition of E. coli (with initial inoculum concentration 10(3) CFU/mL) when LAB have reached maximum density in different conditions of temperature (ranging from 12 ℃ to 30 ℃) and for various inoculum sizes of LAB (ranging from approximately 10(3) to 10(7) CFU/mL). The prediction ability of the microbial competition model (the Baranyi and Roberts model coupled with the Gimenez and Dalgaard model) was first performed only with parameters estimated from individual growth of E. coli and the LAB and then with the introduced competition coefficients evaluated from co-culture growth of E. coli and LAB in milk. Both the results and their statistical indices showed that the model with incorporated average values of competition coefficients improved the prediction of E. coli behaviour in co-culture with LAB. © The Author(s) 2015.

The influences of inoculants from municipal sludge and solid waste on compost stability, maturity and enzyme activities during chicken manure composting.

PubMed

Li, Shuyan; Li, Jijin; Yuan, Jing; Li, Guoxue; Zang, Bing; Li, Yangyang

2017-07-01

The aim of this study was to investigate the influence of inoculants on compost stability, maturity and enzyme activities during composting of chicken manure and cornstalk. Two microbial inoculants (originated from aerobic municipal sludge and municipal solid waste, respectively) were used in composting at the rate of 0.3% of initial raw materials (wet weight). No microbial inoculums were added to the control. The experiment was conducted under aerobic conditions for 53 days. The results show that enzyme activity is an important index to comprehensively evaluate the composting stability and maturity. Microbes originated from sludge works best in terms of composting stability and maturity (C:N ratio decreased from 15.5 to 10, and germination index increased to 109%). Microbial inoculums originated from sludge and municipal solid waste extended the time of thermophilic phase for 11 and 7 days, respectively. Microbial inoculums originated from sludge and MSW significantly increased the average of catalase activity (by 15.0% and 12.1%, respectively), urease activity (by 21.5% and 12.2%, respectively) and cellulase activity (by 32.1% and 26.1%, respectively) during composting.

Comparative assessment of inoculum effects on the antimicrobial activity of amoxycillin-clavulanate and piperacillin-tazobactam with extended-spectrum beta-lactamase-producing and extended-spectrum beta-lactamase-non-producing Escherichia coli isolates.

PubMed

López-Cerero, L; Picón, E; Morillo, C; Hernández, J R; Docobo, F; Pachón, J; Rodríguez-Baño, J; Pascual, A

2010-02-01

A significant inoculum-size effect has been observed with piperacillin-tazobactam, and has been associated with beta-lactamase production in extended-spectrum beta-lactamase (ESBL) producers. This association has not been previously studied in the case of amoxycillin-clavulanate. Piperacillin-tazobactam and amoxycillin-clavulanate were compared, using high inocula of susceptible strains either harbouring ESBLs or not. Two non-ESBL-producing and 15 amoxycillin-clavulanate-susceptible and piperacillin-tazobactam-susceptible ESBL-producing Escherichia coli isolates, and their respective transconjugants, were tested in dilution susceptibility tests using standard and 100-fold higher inocula. Three ESBL-producing strains and E. coli ATCC 25922 were selected for time-kill studies using standard and high initial inocula. At high inocula, MICs of piperacillin increased >eight-fold for non-ESBL-producing strains, and MICs of piperacillin-tazobactam (8:1 ratio or with tazobactam fixed at 4 mg/L) increased>eight-fold for all ESBL-producing strains. However, amoxycillin MICs were not affected by a high inoculum with non-ESBL-producing strains, whereas the MICs of amoxycillin-clavulanate (2:1 and 4:1) increased

The effect of storage conditions on microbial community composition and biomethane potential in a biogas starter culture.

PubMed

Hagen, Live Heldal; Vivekanand, Vivekanand; Pope, Phillip B; Eijsink, Vincent G H; Horn, Svein J

2015-07-01

A new biogas process is initiated by adding a microbial community, typically in the form of a sample collected from a functional biogas plant. This inoculum has considerable impact on the initial performance of a biogas reactor, affecting parameters such as stability, biogas production yields and the overall efficiency of the anaerobic digestion process. In this study, we have analyzed changes in the microbial composition and performance of an inoculum during storage using barcoded pyrosequencing of bacterial and archaeal 16S ribosomal RNA (rRNA) genes, and determination of the biomethane potential, respectively. The inoculum was stored at room temperature, 4 and -20 °C for up to 11 months and cellulose was used as a standard substrate to test the biomethane potential. Storage up to 1 month resulted in similar final methane yields, but the rate of methane production was reduced by storage at -20 °C. Longer storage times resulted in reduced methane yields and slower production kinetics for all storage conditions, with room temperature and frozen samples consistently giving the best and worst performance, respectively. Both storage time and temperature affected the microbial community composition and methanogenic activity. In particular, fluctuations in the relative abundance of Bacteroidetes were observed. Interestingly, a shift from hydrogenotrophic methanogens to methanogens with the capacity to perform acetoclastic methanogensis was observed upon prolonged storage. In conclusion, this study suggests that biogas inocula may be stored up to 1 month with low loss of methanogenic activity, and identifies bacterial and archaeal species that are affected by the storage.

Use of sucrose-agar globule with root exudates for mass production of vesicular arbuscular mycorrhizal fungi.

PubMed

Selvaraj, Thangaswamy; Kim, Hoon

2004-03-01

A sucrose-agar globule (SAG) was newly introduced to increase production of the vesicular arbuscular mycorrhizal (VAM) fungal spores, Gigaspora gigantea and Glomus fasciculatum. An SAG inoculum and a sucrose-agar globule with root exudates (SAGE) inoculum were prepared, and their spore productions were compared with a soil inoculum. When the SAGE was used as the inoculum on sucrose-agar medium plates the number of spores was increased (35% more than the soil inoculum). After the soil inoculum and SAGE were inoculated on an experimental plant, Zingiber officinale, the percentage root colonization, number of VAM spores, and dry matter content were analyzed. It was observed that the SAGE showed a higher percentage of root colonization (about 10% more), and increases in the number of spores (about 26%) and dry matter (more than 13%) for the two VAM fungal spores than the soil inoculum. The results of this study suggested that the SAGE inoculum may be useful for the mass production of VAM fungi and also for the large scale production of VAM fungal fertilizer.

Comparison of various microbial inocula for the efficient anaerobic digestion of Laminaria hyperborea.

PubMed

Sutherland, Alastair D; Varela, Joao C

2014-01-23

The hydrolysis of seaweed polysaccharides is the rate limiting step in anaerobic digestion (AD) of seaweeds. Seven different microbial inocula and a mixture of these (inoculum 8) were therefore compared in triplicate, each grown over four weeks in static culture for the ability to degrade Laminaria hyperborea seaweed and produce methane through AD. All the inocula could degrade L. hyperborea and produce methane to some extent. However, an inoculum of slurry from a human sewage anaerobic digester, one of rumen contents from seaweed-eating North Ronaldsay sheep and inoculum 8 used most seaweed volatile solids (VS) (means ranged between 59 and 68% used), suggesting that these each had efficient seaweed polysaccharide digesting bacteria. The human sewage inoculum, an inoculum of anaerobic marine mud mixed with rotting seaweed and inoculum 8 all developed to give higher volumes of methane (means between 41 and 62.5 ml g-1 of seaweed VS by week four) ,compared to other inocula (means between 3.5 and 27.5 ml g-1 VS). Inoculum 8 also gave the highest acetate production (6.5 mmol g-1 VS) in a single-stage fermenter AD system and produced most methane (8.4 mL mmol acetate-1) in phase II of a two-stage AD system. Overall inoculum 8 was found to be the most efficient inoculum for AD of seaweed. The study therefore showed that selection and inclusion of efficient polysaccharide hydrolysing bacteria and methanogenic archaea in an inoculum offer increased methane productivity in AD of L. hyperborea. This inoculum will now being tested in larger scale (10L) continuously stirred reactors optimised for feed rate and retention time to determine maximum methane production under single-stage and two-stage AD systems.

Comparison of various microbial inocula for the efficient anaerobic digestion of Laminaria hyperborea

PubMed Central

2014-01-01

Background The hydrolysis of seaweed polysaccharides is the rate limiting step in anaerobic digestion (AD) of seaweeds. Seven different microbial inocula and a mixture of these (inoculum 8) were therefore compared in triplicate, each grown over four weeks in static culture for the ability to degrade Laminaria hyperborea seaweed and produce methane through AD. Results All the inocula could degrade L. hyperborea and produce methane to some extent. However, an inoculum of slurry from a human sewage anaerobic digester, one of rumen contents from seaweed-eating North Ronaldsay sheep and inoculum 8 used most seaweed volatile solids (VS) (means ranged between 59 and 68% used), suggesting that these each had efficient seaweed polysaccharide digesting bacteria. The human sewage inoculum, an inoculum of anaerobic marine mud mixed with rotting seaweed and inoculum 8 all developed to give higher volumes of methane (means between 41 and 62.5 ml g-1 of seaweed VS by week four) ,compared to other inocula (means between 3.5 and 27.5 ml g-1 VS). Inoculum 8 also gave the highest acetate production (6.5 mmol g-1 VS) in a single-stage fermenter AD system and produced most methane (8.4 mL mmol acetate-1) in phase II of a two-stage AD system. Conclusions Overall inoculum 8 was found to be the most efficient inoculum for AD of seaweed. The study therefore showed that selection and inclusion of efficient polysaccharide hydrolysing bacteria and methanogenic archaea in an inoculum offer increased methane productivity in AD of L. hyperborea. This inoculum will now being tested in larger scale (10L) continuously stirred reactors optimised for feed rate and retention time to determine maximum methane production under single-stage and two-stage AD systems. PMID:24456825

Effect of varying dietary starch and fiber levels and inoculum source (mule deer vs. dairy cow) on simulated rumen fermentation characteristics.

PubMed

Brooks, Matthew A; Harvey, Robyn M; Johnson, Nichole F; Koutsos, Elizabeth A; Kerley, Monty S

2014-01-01

This study measured starch and fiber digestion and microbial fermentation of three commercial exotic animal feeds using mule deer (MD) or dairy cow (DC) rumen inoculum. Diets were formulated to provide either high starch/low fiber (based on neutral detergent fiber fraction; NDF) with either alfalfa (diet A) or grain and oilseed byproducts (diet B) as the major fiber sources or low starch/high NDF (diet C). An initial batch culture incubation was run with diets inoculated with each rumen inoculum (n = 6; N = 36) over a 48 hr period with samples taken at different hour points for ammonia, pH, lactate, and volatile fatty acids (VFA). A second experiment was conducted where two continuous culture incubations (MD or DC) were run with six single-flow polycarbonate fermentation vessels per dietary treatment. Diets were fed two times a day over an 8-day period and sampled for ammonia, pH, and VFA before and after feeding on the last 3 days. On day 8, fermenter and effluent contents were collected and analyzed for nitrogen, dry matter digestibility (DMD), and organic matter digestibility (OMD). OMD was greater in MD (P = 0.02) and DMD tended to do the same (P = 0.06), but there were no differences due to diet (P > 0.05). Ammonia concentration was greater in DC (P < 0.01), and diets A and B had greater concentrations than diet C (P < 0.01). The greater digestibility, higher acetate:propionate (A:P) ratio and increased lactate levels prior to feeding likely led to diet C having a lower pH than diet A (6.59 vs. 6.66, respectively; P < 0.01) and led the tendency of A to be lower than C after feeding (P = 0.08). A:P ratio was greater in DC than MD before and after feeding (P < 0.01) and was greater in diet C than diets A or B (P < 0.01). Total VFA production tended to be greater in diets B and C in DC (P = 0.06). Rumen fluid source did affect fermentation. Increasing fiber level did not negatively affect fermentation and may increase OMD by removal of negative associative affects by starch on cellulolytic bacteria. © 2014 Wiley Periodicals, Inc.

Mycorrhizal inoculum potentials of pure reclamation materials and revegetated tailing sands from the Canadian oil sand industry.

PubMed

Bois, G; Piché, Y; Fung, M Y P; Khasa, D P

2005-05-01

Recent improvements in the management of oil sand tailings used by the Canadian oil sand industry have resulted in the production of composite tailing sands (CT): a new challenging material for reclamation work. Jack pine (Pinus banksiana Lamb.), hybrid poplar (Populus deltoides Bartr. ex Marsh. xPopulus nigra L.) and red clover (Trifolium pratense L.) plants were used in an 8-week greenhouse bioassay to evaluate the mycorrhizal inoculum potential of CT. This inoculum potential was compared with that of three other reclamation materials [common tailing sands (TS), deep overburden (OB) and muskeg peat (MK)], and with three sites reclaimed in 1982 (R82), 1988 (R88) and 1999 (R99). CT was devoid of active mycorrhizal propagules while all other materials showed some level of inoculum potential. Arbuscular mycorrhizal fungi were observed on roots of clover or poplar grown in TS, OB, and all substrates containing peat (MK, R82, R88 and R99). Pine roots were also colonized by vesicle-forming hyphae of an unidentified fine endophyte and by dark septate fungi. Ectomycorrhizas (ECM) were observed on pine and poplar grown in OB, MK, and in soils from the two older reclaimed sites (R82 and R88). Using morpho- and molecular typing, six ECM fungi were identified to the genus or species level: Laccaria sp., Thelephora americana, Wilcoxina sp. (E-strain), Tuber sp. (I-type), a Sebacinoid, and a Pezizales species. Laccaria sp. and Wilcoxina sp. were the most frequently observed ECM species.

Development of a quantitative loop-mediated isothermal amplification assay for the field detection of Erysiphe necator

USDA-ARS?s Scientific Manuscript database

Plant pathogen detection systems have been useful tools to monitor inoculum presence and initiate management schedules. More recently, a LAMP assay was successfully designed for field use in the grape powdery mildew pathosystem; however, false negatives or false positives were prevalent in grower-co...

Evaluation of 3M™ Molecular Detection Assay (MDA) Listeria for the Detection of Listeria species in Selected Foods and Environmental Surfaces: Collaborative Study, First Action 2014.06.

PubMed

Bird, Patrick; Flannery, Jonathan; Crowley, Erin; Agin, James; Goins, David; Monteroso, Lisa; Benesh, DeAnn

2015-01-01

The 3M™ Molecular Detection Assay (MDA) Listeria is used with the 3M Molecular Detection System for the detection of Listeria species in food, food-related, and environmental samples after enrichment. The assay utilizes loop-mediated isothermal amplification to rapidly amplify Listeria target DNA with high specificity and sensitivity, combined with bioluminescence to detect the amplification. The 3M MDA Listeria method was evaluated using an unpaired study design in a multilaboratory collaborative study and compared to the AOAC Official Method of AnalysisSM (OMA) 993.12 Listeria monocytogenes in Milk and Dairy Products reference method for the detection of Listeria species in full-fat (4% milk fat) cottage cheese (25 g test portions). A total of 15 laboratories located in the continental United States and Canada participated. Each matrix had three inoculation levels: an uninoculated control level (0 CFU/test portion), and two levels artificially contaminated with Listeria monocytogenes, a low inoculum level (0.2-2 CFU/test portion) and a high inoculum level (2-5 CFU/test portion) using nonheat-stressed cells. In total, 792 unpaired replicate portions were analyzed. Statistical analysis was conducted according to the probability of detection (POD) model. Results obtained for the low inoculum level test portions produced a difference in cross-laboratory POD value of -0.07 with a 95% confidence interval of (-0.19, 0.06). No statistically significant differences were observed in the number of positive samples detected by the 3M MDA Listeria method versus the AOAC OMA method.

Enhancing anaerobic digestion of high-pressure extruded food waste by inoculum optimization.

PubMed

Kong, Xin; Xu, Shuang; Liu, Jianguo; Li, Huan; Zhao, Ke; He, Liang

2016-01-15

The inoculation for extruded food waste anaerobic digestion (AD) was optimized to improve methane (CH4) yield. The inoculum of acclimated anaerobic sludge resulted in high biodegradability, producing CH4 yields from 580 mLCH4 g(-1)·VSadded to 605 mLCH4 g(-1)·VSadded, with corresponding BDCH4 ranging from 90% to 94%. We also investigated inoculum to substrate ratios (ISRs). With regards to digested slurry as inoculum, we found that a decrease in ISR improved CH4 yield, while a lower ISR prolonged the lag time of the initial AD stage due to lipid inhibition caused by excessive food waste. These results demonstrate that minimal inocula are required to start the AD system for high-pressure extruded food waste because it is easily biodegraded. High ammonia concentration had a negative effect on CH4 production (i.e., when free ammonia nitrogen [FAN] increased from 20 to 30 mg L(-1) to 120-140 mg L(-1), the CH4 yield decreased by 25%), suggesting that FAN was a significant inhibitor in CH4 yield reduction. In terms of CH4 yield and lag time of the AD process, the optimal inoculation of digested slurry for the extruded food waste had an ISR of 0.33 with CH4 yield of 505 mLCH4 g(-1)VSadded, which was 20% higher than what was found for higher ISR controls of 2, 1 and 0.5. Copyright © 2015 Elsevier Ltd. All rights reserved.

Efficacy of Gaseous Ozone Application during Vacuum Cooling against Escherichia coli O157:H7 on Spinach Leaves as Influenced by Bacterium Population Size.

PubMed

Yesil, Mustafa; Kasler, David R; Huang, En; Yousef, Ahmed E

2017-07-01

Foodborne disease outbreaks associated with the consumption of fresh produce pose a threat to public health, decrease consumer confidence in minimally processed foods, and negatively impact the sales of these commodities. The aim of the study was to determine the influence of population size of inoculated pathogen on its inactivation by gaseous ozone treatment during vacuum cooling. Spinach leaves were spot inoculated with Escherichia coli O157:H7 at approximate initial populations of 10 8 , 10 7 , and 10 5 CFU/g. Inoculated leaves were vacuum cooled (28.5 inHg; 4°C) in a custom-made vessel and then were subjected to a gaseous ozone treatment under the following conditions: 1.5 g of ozone per kg of gas mixture, vessel pressure at 10 lb/in 2 gauge, 94 to 98% relative humidity, and 30 min of holding time at 9°C. Treatment of the leaves, having the aforementioned inocula, decreased E. coli populations by 0.2, 2.1, and 2.8 log CFU/g, respectively, compared with the inoculated untreated controls. Additionally, spinach leaves were inoculated at 1.4 × 10 3 CFU/g, which approximates natural contamination level, and the small populations remaining after ozone treatment were quantified using the most-probable-number (MPN) method. Vacuum and ozone sequential treatment decreased this E. coli O157:H7 population to <3 MPN/g (i.e., greater than 3-log reduction). Resulting log reductions were greater (P < 0.05) at the lower rather than the higher inoculum levels. In conclusion, treatment of spinach leaves with gaseous ozone is effective against pathogen loads comparable to those found in naturally contaminated fresh produce, but efficacy decreases as inoculum level increases.

Effect of inoculum size, bacterial species, type of surfaces and contact time to the transfer of foodborne pathogens from inoculated to non-inoculated beef fillets via food processing surfaces.

PubMed

Gkana, E; Chorianopoulos, N; Grounta, A; Koutsoumanis, K; Nychas, G-J E

2017-04-01

The objective of the present study was to determine the factors affecting the transfer of foodborne pathogens from inoculated beef fillets to non-inoculated ones, through food processing surfaces. Three different levels of inoculation of beef fillets surface were prepared: a high one of approximately 10 7  CFU/cm 2 , a medium one of 10 5  CFU/cm 2 and a low one of 10 3  CFU/cm 2 , using mixed-strains of Listeria monocytogenes, or Salmonella enterica Typhimurium, or Escherichia coli O157:H7. The inoculated fillets were then placed on 3 different types of surfaces (stainless steel-SS, polyethylene-PE and wood-WD), for 1 or 15 min. Subsequently, these fillets were removed from the cutting boards and six sequential non-inoculated fillets were placed on the same surfaces for the same period of time. All non-inoculated fillets were contaminated with a progressive reduction trend of each pathogen's population level from the inoculated fillets to the sixth non-inoculated ones that got in contact with the surfaces, and regardless the initial inoculum, a reduction of approximately 2 log CFU/g between inoculated and 1st non-inoculated fillet was observed. S. Typhimurium was transferred at lower mean population (2.39 log CFU/g) to contaminated fillets than E. coli O157:H7 (2.93 log CFU/g), followed by L. monocytogenes (3.12 log CFU/g; P < 0.05). Wooden surfaces (2.77 log CFU/g) enhanced the transfer of bacteria to subsequent fillets compared to other materials (2.66 log CFU/g for SS and PE; P < 0.05). Cross-contamination between meat and surfaces is a multifactorial process strongly depended on the species, initial contamination level, kind of surface, contact time and the number of subsequent fillet, according to analysis of variance. Thus, quantifying the cross-contamination risk associated with various steps of meat processing and food establishments or households can provide a scientific basis for risk management of such products. Copyright © 2016 Elsevier Ltd. All rights reserved.

Use of sugarcane molasses "B" as an alternative for ethanol production with wild-type yeast Saccharomyces cerevisiae ITV-01 at high sugar concentrations.

PubMed

Fernández-López, C L; Torrestiana-Sánchez, B; Salgado-Cervantes, M A; García, P G Mendoza; Aguilar-Uscanga, M G

2012-05-01

Molasses "B" is a rich co-product of the sugarcane process. It is obtained from the second step of crystallization and is richer in fermentable sugars (50-65%) than the final molasses, with a lower non-sugar solid content (18-33%); this co-product also contains good vitamin and mineral levels. The use of molasses "B" for ethanol production could be a good option for the sugarcane industry when cane sugar prices diminish in the market. In a complex medium like molasses, osmotolerance is a desirable characteristic for ethanol producing strains. The aim of this work was to evaluate the use of molasses "B" for ethanol production using Saccharomyces cerevisiae ITV-01 (a wild-type yeast isolated from sugarcane molasses) using different initial sugar concentrations (70-291 g L(-1)), two inoculum sizes and the addition of nutrients such as yeast extract, urea, and ammonium sulphate to the culture medium. The results obtained showed that the strain was able to grow at 291 g L(-1) total sugars in molasses "B" medium; the addition of nutrients to the culture medium did not produce a statistically significant difference. This yeast exhibits high osmotolerance in this medium, producing high ethanol yields (0.41 g g(-1)). The best conditions for ethanol production were 220 g L(-1) initial total sugars in molasses "B" medium, pH 5.5, using an inoculum size of 6 × 10(6) cell mL(-1); ethanol production was 85 g L(-1), productivity 3.8 g L(-1 )h(-1) with 90% preserved cell viability.

Modeling time to inactivation of Listeria monocytogenes in response to high pressure, sodium chloride, and sodium lactate.

PubMed

Youart, Alyssa M; Huang, Yang; Stewart, Cynthia M; Kalinowski, Robin M; Legan, J David

2010-10-01

A mathematical model was developed to predict time to inactivation (TTI) by high pressure processing of Listeria monocytogenes in a broth system (pH 6.3) as a function of pressure (450 to 700 MPa), inoculum level (2 to 6 log CFU/ml), sodium chloride (1 or 2%), and sodium lactate (0 or 2.5%) from a 4°C initial temperature. Ten L. monocytogenes isolates from various sources, including processed meats, were evaluated for pressure resistance. The five most resistant strains were used as a cocktail to determine TTI and for model validation. Complete inactivation of L. monocytogenes in all treatments was demonstrated with an enrichment method. The TTI increased with increasing inoculum level and decreasing pressure magnitude, from 1.5 min at 700 MPa and 2 log CFU/ml, to 15 min at 450 MPa and 6 log CFU/ml. Neither NaCl nor sodium lactate significantly influenced TTI. The model was validated with ready-to-eat, uncured, Australian retail poultry products, and with product specially made at a U.S. Department of Agriculture, Food Safety and Inspection Service (FSIS)-inspected pilot plant in the United States. Data from the 210 individual product samples used for validation indicate that the model gives "fail-safe" predictions (58% with response as expected, 39% with no survivors where survivors expected, and only 3% with survivors where none were expected). This model can help manufacturers of refrigerated ready-to-eat meats establish effective processing criteria for the use of high pressure processing as a postlethality treatment for L. monocytogenes in accordance with FSIS regulations.

Evaluation of the 3M™ Molecular Detection Assay (MDA) 2 - Salmonella for the Detection of Salmonella spp. in Select Foods and Environmental Surfaces: Collaborative Study, First Action 2016.01.

PubMed

Bird, Patrick; Flannery, Jonathan; Crowley, Erin; Agin, James R; Goins, David; Monteroso, Lisa

2016-07-01

The 3M™ Molecular Detection Assay (MDA) 2 - Salmonella uses real-time isothermal technology for the rapid and accurate detection of Salmonella spp. from enriched select food, feed, and food-process environmental samples. The 3M MDA 2 - Salmonella was evaluated in a multilaboratory collaborative study using an unpaired study design. The 3M MDA 2 - Salmonella was compared to the U.S. Food and Drug Administration Bacteriological Analytical Manual Chapter 5 reference method for the detection of Salmonella in creamy peanut butter, and to the U.S. Department of Agriculture, Food Safety and Inspection Service Microbiology Laboratory Guidebook Chapter 4.08 reference method "Isolation and Identification of Salmonella from Meat, Poultry, Pasteurized Egg and Catfish Products and Carcass and Environmental Samples" for the detection of Salmonella in raw ground beef (73% lean). Technicians from 16 laboratories located within the continental United States participated. Each matrix was evaluated at three levels of contamination: an uninoculated control level (0 CFU/test portion), a low inoculum level (0.2-2 CFU/test portion), and a high inoculum level (2-5 CFU/test portion). Statistical analysis was conducted according to the probability of detection (POD) statistical model. Results obtained for the low inoculum level test portions produced difference in collaborator POD values of 0.03 (95% confidence interval, -0.10 to 0.16) for raw ground beef and 0.06 (95% confidence interval, -0.06 to 0.18) for creamy peanut butter, indicating no statistically significant difference between the candidate and reference methods.

Phage Inactivation of Listeria monocytogenes on San Daniele Dry-Cured Ham and Elimination of Biofilms from Equipment and Working Environments

PubMed Central

Iacumin, Lucilla; Manzano, Marisa; Comi, Giuseppe

2016-01-01

The anti-listerial activity of generally recognized as safe (GRAS) bacteriophage Listex P100 (phage P100) was demonstrated in broths and on the surface of slices of dry-cured ham against 5 strains or serotypes (i.e., Scott A, 1/2a, 1/2b, and 4b) of Listeria monocytogenes. In a broth model system, phage P100 at a concentration equal to or greater than 7 log PFU/mL completely inhibited 2 log CFU/cm2 or 3 log CFU/cm2 of L. monocytogenes growth at 30 °C. The temperature (4, 10, 20 °C) seemed to influence P100 activity; the best results were obtained at 4 °C. On dry-cured ham slices, a P100 concentration ranging from 5 to 8 log PFU/cm2 was required to obtain a significant reduction in L. monocytogenes. At 4, 10, and 20 °C, an inoculum of 8 log PFU/cm2 was required to completely eliminate 2 log L. monocytogenes/cm2 and to reach the absence in 25 g product according to USA food law. Conversely, it was impossible to completely eradicate L. monocytogenes with an inoculum of approximately of 3.0 and 4.0 log CFU/cm2 and with a P100 inoculum ranging from 1 to 7 log PFU/cm2. P100 remained stable on dry-cured ham slices over a 14-day storage period, with only a marginal loss of 0.2 log PFU/cm2 from an initial phage treatment of approximately 8 log PFU/cm2. Moreover, phage P100 eliminated free L. monocytogenes cells and biofilms on the machinery surfaces used for dry-cured ham production. These findings demonstrate that the GRAS bacteriophage Listex P100 at level of 8 log PFU/cm2 is listericidal and useful for reducing the L. monocytogenes concentration or eradicating the bacteria from dry-cured ham. PMID:27681898

Impact of Cropping Systems, Soil Inoculum, and Plant Species Identity on Soil Bacterial Community Structure.

PubMed

Ishaq, Suzanne L; Johnson, Stephen P; Miller, Zach J; Lehnhoff, Erik A; Olivo, Sarah; Yeoman, Carl J; Menalled, Fabian D

2017-02-01

Farming practices affect the soil microbial community, which in turn impacts crop growth and crop-weed interactions. This study assessed the modification of soil bacterial community structure by organic or conventional cropping systems, weed species identity [Amaranthus retroflexus L. (redroot pigweed) or Avena fatua L. (wild oat)], and living or sterilized inoculum. Soil from eight paired USDA-certified organic and conventional farms in north-central Montana was used as living or autoclave-sterilized inoculant into steam-pasteurized potting soil, planted with Am. retroflexus or Av. fatua and grown for two consecutive 8-week periods to condition soil nutrients and biota. Subsequently, the V3-V4 regions of the microbial 16S rRNA gene were sequenced by Illumina MiSeq. Treatments clustered significantly, with living or sterilized inoculum being the strongest delineating factor, followed by organic or conventional cropping system, then individual farm. Living inoculum-treated soil had greater species richness and was more diverse than sterile inoculum-treated soil (observed OTUs, Chao, inverse Simpson, Shannon, P < 0.001) and had more discriminant taxa delineating groups (linear discriminant analysis). Living inoculum soil contained more Chloroflexi and Acidobacteria, while the sterile inoculum soil had more Bacteroidetes, Firmicutes, Gemmatimonadetes, and Verrucomicrobia. Organically farmed inoculum-treated soil had greater species richness, more diversity (observed OTUs, Chao, Shannon, P < 0.05), and more discriminant taxa than conventionally farmed inoculum-treated soil. Cyanobacteria were higher in pots growing Am. retroflexus, regardless of inoculum type, for three of the four organic farms. Results highlight the potential of cropping systems and species identity to modify soil bacterial communities, subsequently modifying plant growth and crop-weed competition.

Large scale field inoculation and scoring of maize southern leaf blight and other maize foliar fungal diseases

USDA-ARS?s Scientific Manuscript database

Field-grown maize is inoculated with Cochliobolus heterostrophus, causal agent of Southern Leaf Blight disease, by dropping sorghum grains infested with the fungus into the whorl of each maize plant at an early stage of growth. The initial lesions produce secondary inoculum that is dispersed by wind...

Effects of inoculum type and bulk dissolved oxygen concentration on achieving partial nitrification by entrapped-cell-based reactors.

PubMed

Rongsayamanont, Chaiwat; Limpiyakorn, Tawan; Khan, Eakalak

2014-07-01

An entrapment of nitrifiers into gel matrix is employed as a tool to fulfill partial nitrification under non-limiting dissolved oxygen (DO) concentrations in bulk solutions. This study aims to clarify which of these two attributes, inoculum type and DO concentration in bulk solutions, is the decisive factor for partial nitrification in an entrapped-cell based system. Four polyvinyl alcohol entrapped inocula were prepared to have different proportions of nitrite-oxidizing bacteria (NOB) and nitrite-oxidizing activity. At a DO concentration of 3 mg l(-1), the number of active NOB cells in an inoculum was the decisive factor for partial nitrification enhancement. However, when the DO concentration was reduced to 2 mg l(-1), all entrapped cell inocula showed similar degrees of partial nitrification. The results suggested that with the lower bulk DO concentration, the preparation of entrapped cell inocula is not useful as the DO level becomes the decisive factor for achieving partial nitrification. Copyright © 2014 Elsevier Ltd. All rights reserved.

Performance assessment of improved composting system for food waste with varying aeration and use of microbial inoculum.

PubMed

Manu, M K; Kumar, Rakesh; Garg, Anurag

2017-06-01

Wet waste recycling at generation point will alleviate burden on the overflowing waste dumpsites in developing nations. Drum composting is a potential treatment option for such waste at individual or community level. The present study was aimed to produce compost from wet waste (primarily comprising food waste) in composting drums modified for improved natural air circulation. Effect of microbial inoculum and waste turning on composting process was also studied. The final results showed the production of matured and stable compost in the modified drums. Addition of the microbial inoculum resulted in thermophilic phase within a week time. The self-heating test and germination index (>80%) showed the production of non-phytotoxic and mature compost in the modified drums after 60days. The change in microbial population, humic substances and biological parameters (lignin, cellulose and hemicellulose) during the study is discussed. Moreover, the reduction in waste mass and volume is also reported. Copyright © 2017 Elsevier Ltd. All rights reserved.

The Effects of Soil Type, Particle Size, Temperature, and Moisture on Reproduction of Belonolaimus longicaudatus.

PubMed

Robbins, R T; Barker, K R

1974-01-01

Effects of soil type, particle size, temperature, and moisture on the reproduction of Belonolaimus longicaudatus were investigated under greenhouse conditions. Nematode increases occurred only in soils with a minimum of 80% sand and a maximum of 10% clay. Optimum soil particle size for reproduction of the Tarboro, N.C. and Tifton, Ga. populations of the nematode was near that of 120-370 mum (65-mesh) silica sand. Reproduction was greatest at 25-30 C. Some reproduction by the Tifton, Ga. population occurred at 35 C, whereas the Tarboro, N.C. population declined, as compared to the initial inoculum. Both populations reproduced slightly at 20 C. Nematode reproduction was greater at a moisture level of 7% than at a high of 30% or a low of 2%. Reproduction occurred at the high moisture level only when the nutrient solution was aerated.

Importance of inoculum properties on the structure and growth of bacterial communities during Recolonisation of humus soil with different pH.

PubMed

Pettersson, Marie; Bååth, Erland

2013-08-01

The relationship between community structure and growth and pH tolerance of a soil bacterial community was studied after liming in a reciprocal inoculum study. An unlimed (UL) humus soil with a pH of 4.0 was fumigated with chloroform for 4 h, after which < 1 % of the initial bacterial activity remained. Half of the fumigated soil was experimentally limed (EL) to a pH of 7.6. Both the UL and the EL soil were then reciprocally inoculated with UL soil or field limed (FL) soil with a pH of 6.2. The FL soil was from a 15-year-old experiment. The structural changes were measured on both bacteria in soil and on bacteria able to grow on agar plates using phospholipids fatty acid (PLFA) and denaturing gradient gel electrophoresis (DGGE) analysis. The developing community pH tolerance and bacterial growth were also monitored over time using thymidine incorporation. The inoculum source had a significant impact on both growth and pH tolerance of the bacterial community in the EL soil. These differences between the EL soil inoculated with UL soil and FL soil were correlated to structural changes, as evidenced by both PLFA and DGGE analyses on the soil. Similar correlations were seen to the fraction of the community growing on agar plates. There were, however, no differences between the soil bacterial communities in the unlimed soils with different inocula. This study showed the connection between the development of function (growth), community properties (pH tolerance) and the structure of the bacterial community. It also highlighted the importance of both the initial properties of the community and the selection pressure after environmental changes in shaping the resulting microbial community.

Laboratory observations of biocide efficiency against Legionella in model cooling tower systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thomas, W.M.; Eccles, J.; Fricker, C.

1999-07-01

The efficacy of specific oxidizing and non-oxidizing biocides was examined using a model cooling system inoculated with a microcosm containing an environmental isolate of Legionella pneumophila. The microcosm was prepared in a two-stage chemostat, which provided a consistent source of microbiological inoculum for the study. The microcosm consisted of both sessile (within biofilms) and planktonic Legionella in association with other microorganisms, including Pseudomonas species and cyst-forming ameobae. A procedure was established to successfully transfer the chemostat grown inoculum to the model cooling system and establish both sessile and planktonic forms of Legionella in the model cooling system. The greatest biocidalmore » effect for all of the biocides was observed immediately after dosing. This effect was relatively short-lived even for the slow acting biocides such isothiazolin (as 8 ppm active) where an effect was only observed over the first 12 hours. The faster acting biocides, DBNPA (as 8 ppm active) and gluteraldehyde (as 27 ppm active), did initially reduce Legionella populations but did not totally eliminate Legionella or provide lasting control. Chlorine and bromine (as 0.5--1.5 ppm free halogen), and ozone (as 0.1--0.5 ppm free reserve) reduced and controlled Legionella populations so long as a free reserve of oxidant was maintained. Legionella recovered quickly after biocide dosing, reestablishing similar levels to those observed before dosing.« less

Assessing the Challenges in the Application of Potential Probiotic Lactic Acid Bacteria in the Large-Scale Fermentation of Spanish-Style Table Olives.

PubMed

Rodríguez-Gómez, Francisco; Romero-Gil, Verónica; Arroyo-López, Francisco N; Roldán-Reyes, Juan C; Torres-Gallardo, Rosa; Bautista-Gallego, Joaquín; García-García, Pedro; Garrido-Fernández, Antonio

2017-01-01

This work studies the inoculation conditions for allowing the survival/predominance of a potential probiotic strain ( Lactobacillus pentosus TOMC-LAB2) when used as a starter culture in large-scale fermentations of green Spanish-style olives. The study was performed in two successive seasons (2011/2012 and 2012/2013), using about 150 tons of olives. Inoculation immediately after brining (to prevent wild initial microbiota growth) followed by re-inoculation 24 h later (to improve competitiveness) was essential for inoculum predominance. Processing early in the season (September) showed a favorable effect on fermentation and strain predominance on olives (particularly when using acidified brines containing 25 L HCl/vessel) but caused the disappearance of the target strain from both brines and olives during the storage phase. On the contrary, processing in October slightly reduced the target strain predominance on olives (70-90%) but allowed longer survival. The type of inoculum used (laboratory vs. industry pre-adapted) never had significant effects. Thus, this investigation discloses key issues for the survival and predominance of starter cultures in large-scale industrial fermentations of green Spanish-style olives. Results can be of interest for producing probiotic table olives and open new research challenges on the causes of inoculum vanishing during the storage phase.

Comparison of two possible routes of pathogen contamination of spinach leaves in a hydroponic cultivation system.

PubMed

Koseki, Shigenobu; Mizuno, Yasuko; Yamamoto, Kazutaka

2011-09-01

The route of pathogen contamination (from roots versus from leaves) of spinach leaves was investigated with a hydroponic cultivation system. Three major bacterial pathogens, Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes, were inoculated into the hydroponic solution, in which the spinach was grown to give concentrations of 10⁶ and 10³ CFU/ml. In parallel, the pathogens were inoculated onto the growing leaf surface by pipetting, to give concentrations of 10⁶ and 10³ CFU per leaf. Although contamination was observed at a high rate through the root system by the higher inoculum (10⁶ CFU) for all the pathogens tested, the contamination was rare when the lower inoculum (10³ CFU) was applied. In contrast, contamination through the leaf occurred at a very low rate, even when the inoculum level was high. For all the pathogens tested in the present study, the probability of contamination was promoted through the roots and with higher inoculum levels. The probability of contamination was analyzed with logistic regression. The logistic regression model showed that the odds ratio of contamination from the roots versus from the leaves was 6.93, which suggested that the risk of contamination from the roots was 6.93 times higher than the risk of contamination from the leaves. In addition, the risk of contamination by L. monocytogenes was about 0.3 times that of Salmonella enterica subsp. enterica serovars Typhimurium and Enteritidis and E. coli O157:H7. The results of the present study indicate that the principal route of pathogen contamination of growing spinach leaves in a hydroponic system is from the plant's roots, rather than from leaf contamination itself.

Co-digestion of ruminal content and blood from slaughterhouse industries: influence of solid concentration and ammonium generation.

PubMed

López, I; Passeggi, M; Borzacconi, L

2006-01-01

At the present time, organic solid wastes from industries and agricultural activities are considered to be promising substrates for biogas production via anaerobic digestion. Moreover solids stabilisation is required before reutilization or disposal. Slaughterhouses are among the most important industries in Uruguay and produce 150,000 tons of ruminal content (RC) and 30,000 tons of blood per year. In order to determine the influence of the solids and blood contents, the ammonia inhibition and the inoculum adaptation co-digestion batch tests were performed. A set of experiences with TS concentration of 2.5%, 5% and 7.5% and different ratios of RC/blood were carried out using an inoculum from an UASB reactor. In all experiences fast blood hydrolisation was observed. A higher methane production was detected in the experiences with higher TS content. However, the fraction of solids degradation was lower in these experiences. A plateau in the biogas production was found. The free ammonia level, which was above the reported inhibitory levels, could explain this behaviour. After the inhibition period the biogas production restarted probably due to the biomass acclimatisation to the ammonia. In order to determine the inoculum adaptation a new experiment was performed. The inoculum used was the sludge coming from the first set of experiences. Based upon batch tests a 3.5 m3 pilot reactor was designed and started up. Ammonia inhibition was avoided by the start-up strategy and in two weeks the biogas production was 3.5 m3/d. The VS stabilisation with a solid retention time of 20 days was of 43%. The pilot reactor working at steady state had a TS concentration of 3-4% with a ratio of RC/blood of 10:1 at the entrance.

Housefly maggot-treated composting as sustainable option for pig manure management.

PubMed

Zhu, Feng-Xiang; Yao, Yan-Lai; Wang, Su-Juan; Du, Rong-Guang; Wang, Wei-Ping; Chen, Xiao-Yang; Hong, Chun-Lai; Qi, Bing; Xue, Zhi-Yong; Yang, Hong-Quan

2015-01-01

In traditional composting, large amounts of bulking agents must be added to reduce the moisture of pig manure, which increases the cost of composting and dilutes the N, P and K content in organic fertilizers. In this study, maggot treatment was used in composting instead of bulking agents. In experiment of selecting an optimal inoculum level for composting, the treatment of 0.5% maggot inoculum resulted in the maximum yield of late instar maggots, 11.6% (maggots weight/manure weight). The manure residue became noticeably granular by day 6 and its moisture content was below 60%, which was suitable for further composting without bulking agents. Moreover, in composting experiment with a natural compost without maggot inoculum and maggot-treated compost at 0.5% inoculum level, there were no significant differences in nutrient content between the two organic fertilizers from the two treatments (paired Student's t15=1.0032, P=0.3317). Therefore, maggot culturing did not affect the characteristics of the organic fertilizer. The content of TNPK (total nitrogen+total phosphorus+total potassium) in organic fertilizer from maggot treatment was 10.72% (dry weight), which was far more than that of organic fertilizer made by conventional composting with bulking agents (about 8.0%). Dried maggots as feed meet the national standard (GB/T19164-2003) for commercial fish meal in China, which contained 55.32 ± 1.09% protein; 1.34 ± 0.02% methionine; 4.15 ± 0.10% lysine. This study highlights housefly maggot-treated composting can be considered sustainable alternatives for pig manure management to achieve high-quality organic fertilizer and maggots as feed without bulking agents. Copyright © 2014 Elsevier Ltd. All rights reserved.

Mechanisms for the development of genetically variable mycorrhizal mycelia in the ectomycorrhizal fungus Laccaria bicolor.

PubMed Central

de la Bastide, P Y; Kropp, B R; Piché, Y

1995-01-01

An in vitro study investigated mechanisms for the development of genetically variable mycorrhizal mycelia for Laccaria bicolor. Seedlings of jack pine (Pinus banksiana) grown nonaseptically in an autoclaved soil substrate were given different L. bicolor inoculum treatments. These included (i) a dikaryotic mycelium genotype (D); (ii) D and basidiospores collected from one group of five sporophores (T1); (iii) D and basidiospores collected from 10 sporophores, two from each of five different groups (T5); (iv) T1 alone; (v) T5 alone; and (vi) a noninoculated control. Dikaryotic mycelial inoculum was provided at the time of sowing, while basidiospore inoculum was added at 10 weeks after seed germination. Sporophore formation was induced after 20 weeks of growth, and dikaryotic cultures were isolated from their tissue. Seedlings were harvested, and growth and mycorrhization were assessed. Levels of both were generally lower for T1-treated seedlings, compared with seedlings receiving D, while levels for T5-treated seedlings were intermediate. Sporophore genotype variability was assessed for inoculum treatments by using the isoenzymatic marker leucine aminopeptidase. The greatest genetic variability was seen with the basidiospore treatments T1 and T5, with up to four leucine aminopeptidase patterns per seedling. The mixed treatments D plus T1 and D plus T5 produced most frequently, but not exclusively, the inoculated dikaryon genotype. After isoenzyme results were assessed, variable sporophore isolates of mixed treatments were analyzed with randomly amplified polymorphic DNA and PCR mitochondrial DNA markers to determine if they were formed by dikaryon-monokaryon crosses between the inoculated dikaryon and monosporous mycelia.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7486997

Inoculum Potential of Fusarium spp. Relates to Tillage and Straw Management in Norwegian Fields of Spring Oats

PubMed Central

Hofgaard, Ingerd S.; Seehusen, Till; Aamot, Heidi U.; Riley, Hugh; Razzaghian, Jafar; Le, Vinh H.; Hjelkrem, Anne-Grete R.; Dill-Macky, Ruth; Brodal, Guro

2016-01-01

The increased occurrence of Fusarium-mycotoxins in Norwegian cereals over the last decade, is thought to be caused by increased inoculum resulting from more cereal residues at the soil surface as a result of reduced tillage practices. In addition, weather conditions have increasingly promoted inoculum development and infection by Fusarium species. The objective of this work was to elucidate the influence of different tillage regimes (autumn plowing; autumn harrowing; spring plowing; spring harrowing) on the inoculum potential (IP) and dispersal of Fusarium spp. in spring oats. Tillage trials were conducted at two different locations in southeast Norway from 2010 to 2012. Oat residues from the previous year’s crop were collected within a week after sowing for evaluation. IP was calculated as the percentage of residues infested with Fusarium spp. multiplied by the proportion of the soil surface covered with residues. Fusarium avenaceum and F. graminearum were the most common Fusarium species recovered from oat residues. The IP of Fusarium spp. was significantly lower in plowed plots compared to those that were harrowed. Plowing in either the autumn or spring resulted in a low IP. Harrowing in autumn was more effective in reducing IP than the spring harrowing, and IP levels for the spring harrowed treatments were generally higher than all other tillage treatments examined. Surprisingly low levels of F. langsethiae were detected in the residues, although this species is a common pathogen of oat in Norway. The percentage of the residues infested with F. avenaceum, F. graminearum, F. culmorum, and F. langsethiae generally related to the quantity of DNA of the respective Fusarium species determined using quantitative PCR (qPCR). Fusarium dispersal, quantified by qPCR analysis of spore trap samples collected at and after heading, generally corresponded to the IP. Fusarium dispersal was also observed to increase after rainy periods. Our findings are in line with the general understanding that plowing is a means to reduce the IP of Fusarium spp. in cereal fields. The main inoculum source for F. langsethiae remains unclear. Our results will be useful in the development of forecasting tools to calculate the risk of Fusarium in cereals. PMID:27148236

Effect of Trichoderma on horticultural seedlings' growth promotion depending on inoculum and substrate type.

PubMed

Marín-Guirao, J I; Rodríguez-Romera, P; Lupión-Rodríguez, B; Camacho-Ferre, F; Tello-Marquina, J C

2016-10-01

The biostimulant effect of Trichoderma spp. on horticultural crops are highly variable. Thus, practical use of Trichoderma sp. requires feasible formulated products and suitable substrates. This study evaluates the survival and the growth-promotion effect of a Trichoderma saturnisporum rice formulation compared with a nonformulated conidia suspension (seven treatments in total), on tomato, pepper and cucumber seedlings grown in two substrates: (i) rich in organic matter (OM) and (ii) mineral substrate without OM. The results showed beneficial effects on seedling growth in the OM-rich substrate when T. saturnisporum rice formulation (mainly at maximum concentration) was applied, but the effects were opposite when the mineral substrate without OM was used. The effects were closely linked to the level of inoculum in the substrate, which was greater upon application of the formulated inoculum as opposed to the nonformulated one. The use of rice to prepare the inoculum of T. saturnisporum seems to be promising for seedling growth in the nursery when it is applied in a substrate that is rich in organic matter, but it must be considered that under certain conditions of food shortage, Trichoderma sp. could show pathogenicity to seedlings. This study provides evidence of the complexity inherent in the use of micro-organisms in agriculture, while also confirming that the activity of the biofertilizers based on Trichoderma depends on the type of inoculum and its concentration, as well as the properties of the medium in which the fungi develop. Further studies assessing the effectiveness or possible pathogenicity of Trichoderma in different soils under greenhouse conditions must be addressed. © 2016 The Society for Applied Microbiology.

The effect of cultivation on the size, shape, and persistence of disease patches in fields.

PubMed

Truscott, J E; Gilligan, C A

2001-06-19

Epidemics of soil-borne plant disease are characterized by patchiness because of restricted dispersal of inoculum. The density of inoculum within disease patches depends on a sequence comprising local amplification during the parasitic phase followed by dispersal of inoculum by cultivation during the intercrop period. The mechanisms that control size, shape, and persistence have received very little rigorous attention in epidemiological theory. Here we derive a model for dispersal of inoculum in soil by cultivation that takes account into the discrete stochastic nature of the system in time and space. Two parameters, probability of movement and mean dispersal distance, characterize lateral dispersal of inoculum by cultivation. The dispersal parameters are used in combination with the characteristic area and dimensions of host plants to identify criteria that control the shape and size of disease patches. We derive a critical value for the probability of movement for the formation of cross-shaped patches and show that this is independent of the amount of inoculum. We examine the interaction between local amplification of inoculum by parasitic activity and subsequent dilution by dispersal and identify criteria whereby asymptomatic patches may persist as inoculum falls below a threshold necessary for symptoms to appear in the subsequent crop. The model is motivated by the spread of rhizomania, an economically important soil-borne disease of sugar beet. However, the results have broad applicability to a very wide range of diseases that survive as discrete units of inoculum. The application of the model to patch dynamics of weed seeds and local introductions of genetically modified seeds is also discussed.

Kinetic study of dry anaerobic co-digestion of food waste and cardboard for methane production.

PubMed

Capson-Tojo, Gabriel; Rouez, Maxime; Crest, Marion; Trably, Eric; Steyer, Jean-Philippe; Bernet, Nicolas; Delgenès, Jean-Philippe; Escudié, Renaud

2017-11-01

Dry anaerobic digestion is a promising option for food waste treatment and valorization. However, accumulation of ammonia and volatile fatty acids often occurs, leading to inefficient processes and digestion failure. Co-digestion with cardboard may be a solution to overcome this problem. The effect of the initial substrate to inoculum ratio (0.25 to 1gVS·gVS -1 ) and the initial total solids contents (20-30%) on the kinetics and performance of dry food waste mono-digestion and co-digestion with cardboard was investigated in batch tests. All the conditions produced methane efficiently (71-93% of the biochemical methane potential). However, due to lack of methanogenic activity, volatile fatty acids accumulated at the beginning of the digestion and lag phases in the methane production were observed. At increasing substrate to inoculum ratios, the initial acid accumulation was more pronounced and lower cumulative methane yields were obtained. Higher amounts of soluble organic matter remained undegraded at higher substrate loads. Although causing slightly longer lag phases, high initial total solids contents did not jeopardize the methane yields. Cardboard addition reduced acid accumulation and the decline in the yields at increasing substrate loads. However, cardboard addition also caused higher concentrations of propionic acid, which appeared as the most last acid to be degraded. Nevertheless, dry co-digestion of food waste and cardboard in urban areas is demonstrated asan interesting feasible valorization option. Copyright © 2017 Elsevier Ltd. All rights reserved.

Survival of human pathogenic bacteria in different types of natural mineral water.

PubMed

Serrano, Concepción; Romero, Margarita; Alou, Luis; Sevillano, David; Corvillo, Iluminada; Armijo, Francisco; Maraver, Francisco

2012-09-01

The aim of this study was to determine the survival of human pathogens (Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa) in five natural mineral waters (NMWs) with different properties and mineralization levels. Five NMWs from four Spanish spas with different dry residue at 110 °C were used: A = 76,935 mg/L; B = 1,827 mg/L; C = 808.4 mg/L; D = 283.8 mg/L; and E = 170.4 mg/L. An initial inoculum of 1 × 10(6) colony forming units (cfu)/mL was used for survival studies. Distilled water, chlorinated tap water and Mueller-Hinton broth were used as controls. Colony counts in all different waters were lower than those achieved with Mueller-Hinton broth over all incubation periods. A direct effect between the bacterial survival and the level of mineralization water was observed. The NMW E with low mineralization level along with the radioactive properties showed the highest antibacterial activity among all NMWs.

The effects of arbuscular mycorrhizal fungal inoculation at a roadside prairie restoration site.

PubMed

White, Jennifer A; Tallaksen, J; Charvat, I

2008-01-01

Arbuscular mycorrhizal fungi (AMF) may play an important role in ecological succession, but few studies have documented the effectiveness of mycorrhizal inoculation at restoration/reclamation sites. At a roadside prairie restoration in Shakopee, Minnesota, we compared AMF root colonization and resulting vegetative cover among four inoculation treatments. After 15 mo of growth, we found that AMF colonization was high in all treatments but was significantly higher in treatments that received AMF inoculum propagated from a local prairie site or commercially available inoculum than the uninoculated control. For the prairie inoculum, this increase in colonization occurred whether the inoculum was applied with seeds in furrows or broadcast with seeds on the soil surface. However, increased colonization did not discernibly affect the restored vegetation; neither total vegetative cover nor the proportion "desired" prairie vegetation differed among inoculation treatments. By the end of the third growing season (27 mo after planting) there were no longer differences in AMF colonization among the inoculation treatments nor were there differences in vegetative cover. It is likely that natural recolonization of the plots by remnant AMF populations at the site limited the duration of the inoculation effect. This natural recolonization, in combination with relatively high soil phosphorus levels, likely rendered inoculation unnecessary. In contrast to previous published studies of AMF inoculation in landscape restorations, this study shows that AMF inoculation may not be warranted under some circumstances.

Improvement of ε-poly-L-lysine production through seed stage development based on in situ pH monitoring.

PubMed

Sun, Qi-Xing; Chen, Xu-Sheng; Ren, Xi-Dong; Mao, Zhong-Gui

2015-01-01

Nissin, natamycin, and ε-poly-L-lysine (ε-PL) are three safe, microbial-produced food preservatives used today in the food industry. However, current industrial production of ε-PL is only performed in several countries. In order to realize large-scale ε-PL production by fermentation, the effects of seed stage on cell growth and ε-PL production were investigated by monitoring of pH in situ in a 5-L laboratory-scale fermenter. A significant increase in ε-PL production in fed-batch fermentation by Streptomyces sp. M-Z18 was achieved, at 48.9 g/L, through the optimization of several factors associated with seed stage, including spore pretreatment, inoculum age, and inoculum level. Compared with conventional fermentation approaches using 24-h-old shake-flask seed broth as inoculum, the maximum ε-PL concentration and productivity were enhanced by 32.3 and 36.6 %, respectively. The effect of optimized inoculum conditions on ε-PL production on a large scale was evaluated using a 50-L pilot-scale fermenter, attaining a maximum ε-PL production of 36.22 g/L in fed-batch fermentation, constituting the first report of ε-PL production at pilot scale. These results will be helpful for efficient ε-PL production by Streptomyces at pilot and plant scales.

The effect of methanogenesis inhibition, inoculum and substrate concentration on hydrogen and carboxylic acids production from cassava wastewater.

PubMed

Amorim, Norma C S; Amorim, Eduardo L C; Kato, Mario T; Florencio, Lourdinha; Gavazza, Savia

2018-02-01

Manipueira is a carbohydrate-rich agro-industrial waste from cassava processing. It is considered well suitable for biotechnological processes, such as hydrogen and carboxylic acids production, due to the high content of easily degradable organic matter. However, the proper methanogenesis inhibition method, inoculum type, and organic loads are factors still limiting the processes. The objective in this work was to evaluate the effects of such factors on byproducts production in anaerobic reactors. Batch experiments were conducted with 2.3-L flasks during two operational phases. In the first phase (P1), inhibition of methanogens in the sludge was evaluated using acetylene (1% v/v of headspace) and heat treatment (120 °C, 1 atm for 30 min). In the second phase (P2), three inoculum types obtained from common anaerobic sludges (bovine rumen and sludges from municipal and textile industrial wastewater treatment plants) were individually assayed. P2 aimed to identify the best inoculum, based on hydrogen production ability, which was tested for three initial concentrations of manipueira in terms of chemical oxygen demand (COD) (10, 20 and 40 g O 2 /L). Results of P1 indicated that either acetylene or heat treatment efficiently inhibited methanogenesis, with no methane production. However, the maximum H 2 production potential by applying heat treatment (~ 563 mL) was more than twice compared with that by acetylene treatment (~ 257 mL); and butyrate was the main carboxylic acid by-product (~ 3 g/L). In P2 experiments after sludge heat treatment, the highest hydrogen yield (1.66 ± 0.07 mol H 2 /mol glucose) and caproic acid production (~ 2 g/L) were observed at 20 g O 2 /L of manipueira COD, when bovine rumen was the inoculum. The primary metabolic degradation products in all P2 experiments were ethanol, acetic, butyric, propionic and caproic acids. The finding of caproic acid detection indicated that the applied conditions in manipueira anaerobic degradation favored carbon chain elongation over methanogenesis.

Hairy nightshade as a potential Potato leafroll virus (Luteoviridae: Polerovirus) inoculum source in Pacific Northwest potato ecosystems.

PubMed

Srinivasan, R; Alvarez, J M

2008-09-01

Hairy nightshade, Solanum sarrachoides, is a solanaceous weed found abundantly in Pacific Northwest potato ecosystems. It serves as a reservoir for one of the important potato viruses, Potato leafroll virus (PLRV) (Luteoviridae: Polerovirus), and its most important vector, the green peach aphid, Myzus persicae (Homoptera: Aphididae). Laboratory research indicated an increased green peach aphid settling and performance on S. sarrachoides than on potato. It also revealed that green peach aphids transmitted PLRV more efficiently from S. sarrachoides to potato than from potato to potato. To test the efficiency of S. sarrachoides as an inoculum source in the field, a two season (2004 and 2005) trial was conducted at Kimberly, Idaho. Two inoculum sources, PLRV-infected potato and PLRV-infected S. sarrachoides, were compared in this trial. Green peach aphid density and temporal and spatial PLRV spread were monitored at weekly intervals. Higher densities of green peach aphids were observed on plots with S. sarrachoides and inoculum sources (PLRV-infected S. sarrachoides and potato) than on plots without S. sarrachoides and inoculum sources. PLRV infection in plots with PLRV-infected S. sarrachoides was similar to or slightly higher than in plots with PLRV-infected potato as an inoculum source. Temporal and spatial PLRV spread was similar in plots with either inoculum source. Thus, S. sarrachoides is as efficient as or a better PLRV inoculum source than potato.

Effects of operational parameters on dark fermentative hydrogen production from biodegradable complex waste biomass.

PubMed

Ghimire, Anish; Sposito, Fabio; Frunzo, Luigi; Trably, Eric; Escudié, Renaud; Pirozzi, Francesco; Lens, Piet N L; Esposito, Giovanni

2016-04-01

This work aimed to investigate the effect of the initial pH, combination of food to microorganism ratio (F/M) and initial pH, substrate pre-treatment and different inoculum sources on the dark fermentative biohydrogen (H2) yields. Three model complex waste biomasses (food waste, olive mill wastewater (OMWW) and rice straw) were used to assess the effect of the aforementioned parameters. The effect of the initial pH between 4.5 and 7.0 was investigated in batch tests carried out with food waste. The highest H2 yields were shown at initial pH 4.5 (60.6 ± 9.0 mL H2/g VS) and pH 5.0 (50.7 ± 0.8 mL H2/g VS). Furthermore, tests carried out with F/M ratios of 0.5, 1.0 and 1.5 at initial pH 5.0 and 6.5 revealed that a lower F/M ratio (0.5 and 1.0) favored the H2 production at an initial pH 5.0 compared to pH 6.5. Alkaline pre-treatment of raw rice straw using 4% and 8% NaOH at 55°C for 24h, increased the H2 yield by 26 and 57-fold, respectively. In the dark fermentation of OMWW, the H2 yield was doubled when heat-shock pre-treated activated sludge was used as inoculum in comparison to anaerobic sludge. Overall, this study shows that the application of different operating parameters to maximize the H2 yields strongly depends on the biodegradability of the substrate. Copyright © 2016 Elsevier Ltd. All rights reserved.

Relative heat sensitivities of certain Phytophthora spp. and the potential for soil solarization to disinfest nursery beds in West Coast states

Treesearch

Jennifer L. Parke; Fumiaki Funahashi; Clara Weidman; Ebba K. Peterson

2017-01-01

Soilborne Phytophthora spp. can be important for initiating disease through movement of inoculum with surface water to roots or splashing onto foliage. Nursery beds infested with Phytophthora spp. can contaminate container plants set on them, causing disease year after year and posing a risk of additional spread....

The efficiency of introduced pisolithus tinctorius inoculum on backcrossed chestnut germination and survival

Treesearch

Jenise M. Bauman; Carolyn H. Keiffer; Shiv Hiremath

2012-01-01

American chestnut was eliminated as a canopy tree from the Appalachian region of North America with the introduction of chestnut blight in the early 1900s. Breeding programs initiated in the 1980s have produced seedling lines that display the pure American morphology with potential resistance to chestnut blight. More work is required to assess their field performance...

Extrahepatic exoerythrocytic forms of rodent malaria parasites at the site of inoculation: clearance after immunization, susceptibility to primaquine, and contribution to blood-stage infection.

PubMed

Voza, Tatiana; Miller, Jessica L; Kappe, Stefan H I; Sinnis, Photini

2012-06-01

Plasmodium sporozoites are inoculated into the skin of the mammalian host as infected mosquitoes probe for blood. A proportion of the inoculum enters the bloodstream and goes to the liver, where the sporozoites invade hepatocytes and develop into the next life cycle stage, the exoerythrocytic, or liver, stage. Here, we show that a small fraction of the inoculum remains in the skin and begins to develop into exoerythrocytic forms that can persist for days. Skin exoerythrocytic forms were observed for both Plasmodium berghei and Plasmodium yoelii, two different rodent malaria parasites, suggesting that development in the skin of the mammalian host may be a common property of plasmodia. Our studies demonstrate that skin exoerythrocytic stages are susceptible to destruction in immunized mice, suggesting that their aberrant location does not protect them from the host's adaptive immune response. However, in contrast to their hepatic counterparts, they are not susceptible to primaquine. We took advantage of their resistance to primaquine to test whether they could initiate a blood-stage infection directly from the inoculation site, and our data indicate that these stages are not able to initiate malaria infection.

Isolation of a bacteriocin-producing Lactococcus lactis subsp. lactis and application to control Listeria monocytogenes in Moroccan jben.

PubMed

Benkerroum, N; Oubel, H; Zahar, M; Dlia, S; Filali-Maltouf, A

2000-12-01

Use of a bacteriocin-producing lactococcal strain to control Listeria monocytogenes in jben. A Lactococcus lactis strain isolated from lben was shown, by the spot technique, to produce a bacteriocin different from nisin. Inhibitory activity of the bacteriocin-producing strain against Listeria monocytogenes was investigated in jben, made from cow's milk fermented with the producer organism and contaminated with 104 or 107 cfu ml-1. Listeria counts were monitored during manufacture, and during conservation at room and at refrigeration temperatures. Results showed that the pathogen was reduced by 2.7 logarithmic units after 30 h of jben processing when the initial inoculum of 107 cfu ml(-1) was used. For the initial inoculum of 104 cfu ml(-1), the bacterium was completely eliminated at 24 h. Furthermore, the use of the bacteriocin-producing starter culture extended the shelf-life of jben by 5 days. In situ production of the lactococcal bacteriocin is an efficient biological means of controlling L. monocytogenes in jben and of allowing shelf-life extension. The proposed technology will essentially benefit minimally processed dairy products and those made with raw milk.

Effect of Monascus purpureus inoculum concentration on pigment production in jackfruit seed flour substrate

NASA Astrophysics Data System (ADS)

Hamdiyati, Yanti; Kusnadi, Yuliani, Lia Amelia

2016-02-01

The used of synthetic dyes have various negative effects on human health. Roomates pigment produced by Monascus purpureus mold can be used as an alternative natural food coloring. The research on the effect of inoculum concentration's M. purpureus to pigment production on the jackfruit seed flour has been done. The objective of research to is to investigate the effect of inoculum concentration's M. purpureus to the production of red, yellow and orange pigment on the jackfruit seed flour. The concentrations used were 0%, 5%, 10%, and 15% (v/w). The result of the data analysed using One-Way ANOVA showed that the inoculum concentration affected the production of red pigment M. purpureus, as well as the data analysis using the Kruskal-Wallis showed that inoculum concentration has influence on the production of yellow and orange pigments. Inoculum concentration of 15% is the optimum concentration for the production of red, yellow and orange pigments with 0:10, 0:50 and 0:20 absorbance units per gram of sample respectively. Based on the results of the research, it can be concluded that inoculum concentration of M. purpureus influenced the production of red, yellow and orange pigments.

Inoculum selection influences the biochemical methane potential of agro-industrial substrates

PubMed Central

De Vrieze, Jo; Raport, Linde; Willems, Bernard; Verbrugge, Silke; Volcke, Eveline; Meers, Erik; Angenent, Largus T; Boon, Nico

2015-01-01

Obtaining a reliable estimation of the methane potential of organic waste streams in anaerobic digestion, for which a biochemical methane potential (BMP) test is often used, is of high importance. Standardization of this BMP test is required to ensure inter-laboratory repeatability and accuracy of the BMP results. Therefore, guidelines were set out; yet, these do not provide sufficient information concerning origin of and the microbial community in the test inoculum. Here, the specific contribution of the methanogenic community on the BMP test results was evaluated. The biomethane potential of four different substrates (molasses, bio-refinery waste, liquid manure and high-rate activated sludge) was determined by means of four different inocula from full-scale anaerobic digestion plants. A significant effect of the selected inoculum on the BMP result was observed for two out of four substrates. This inoculum effect could be attributed to the abundance of methanogens and a potential inhibiting effect in the inoculum itself, demonstrating the importance of inoculum selection for BMP testing. We recommend the application of granular sludge as an inoculum, because of its higher methanogenic abundance and activity, and protection from bulk solutions, compared with other inocula. PMID:25756301

Internalization of Murine Norovirus 1 by Lactuca sativa during Irrigation ▿

PubMed Central

Wei, Jie; Jin, Yan; Sims, Tom; Kniel, Kalmia E.

2011-01-01

Romaine lettuce (Lactuca sativa) was grown hydroponically or in soil and challenged with murine norovirus 1 (MNV) under two conditions: one mimicking a severe one-time contamination event and another mimicking a lower level of contamination occurring over time. In each condition, lettuce was challenged with MNV delivered at the roots. In the first case, contamination occurred on day one with 5 × 108 reverse transcriptase quantitative PCR (RT-qPCR) U/ml MNV in nutrient buffer, and irrigation water was replaced with virus-free buffer every day for another 4 days. In the second case, contamination with 5 × 105 RT-qPCR U/ml MNV (freshly prepared) occurred every day for 5 days. Virus had a tendency to adsorb to soil particles, with a small portion suspended in nutrient buffer; e.g., ∼8 log RT-qPCR U/g MNV was detected in soil during 5 days of challenge with virus inoculums of 5 × 108 RT-qPCR U/ml at day one, but <6 log was found in nutrient buffer on days 3 and 5. For hydroponically grown lettuce, ∼3.4 log RT-qPCR U of viral RNA/50 mg of plant tissue was detected in some lettuce leaf samples after 5 days at high MNV inoculums, significantly higher than the internalized virus concentration (∼2.6 log) at low inoculums (P < 0.05). For lettuce grown in soil, approximately 2 log RT-qPCR U of viral RNA/50 mg of plant tissue was detected in lettuce with both high and low inoculums, showing no significant difference. For viral infectivity, infectious MNV was found in lettuce samples challenged with high virus inoculums grown hydroponically and in soil but not in lettuce grown with low virus inoculums. Lettuce grown hydroponically was further incubated in 99% and 70% relative humidities (RH) to evaluate plant transpiration relative to virus uptake. More lettuce samples were found positive for MNV at a significantly higher transpiration rate at 70% RH, indicating that transpiration might play an important role in virus internalization into L. sativa. PMID:21296944

Inhibitory activity of bacteriocin produced from Lactobacillus SCG 1223 toward L. monocytogenes, S. thypimurium and E. coli

NASA Astrophysics Data System (ADS)

Marwati, T.; Cahyaningrum, N.; Widodo, S.; Januarsyah, T.; Purwoko

2018-01-01

Bacteriocin is a protein compound which has bactericidal ability against pathogen bacteria. This research aims to study the inhibitory activity of bacteriocin produced from Lactobacillus SCG 1223 against Listeria monocytogenes, Salmonella thypimuruim and Escherchia coli. The bacteriocin produce from Lactobacillus SCG 1223 in the MRS broth media The experimental design used was Completely Randomized Design. The variations used in this design were percentage of inoculum (5%, 10%), medium pH (4, 6), incubation temperature (27°C, 40°C), and incubation time (4, 10, 14 hours). Result showed that bacteriocin from Lactobacillus SCG 1223 had wide spectrum toward L. monocytogenes, S. thypimuruim and E. coli. The highest bacteriocin activity toward L. monocytogenes produced by Lactobacillus SCG 1223 with 10% inoculum in media with initial pH 6, incubation temperature 27°C for 14 hour, toward S. thypimurium produced by Lactobacillus SCG 1223 with in media with initial pH 6, incubation temperature 40°C for 14 hour, and toward E. coli was 1085.81 AU/ml, produced by Lactobacillus SCG 1223 in MRS broth with initial pH 4, incubation temperature 40°C for 14 hour. This study is expected to find a new food preservative that can inhibit the growth of pathogenic bacteria and extend the shelf life of food. From the economic prospective of view, bacteriocin is very promising natural alternative biopreservatives.

The role of inoculum's origin on the methane yield of different substrates in biochemical methane potential (BMP) tests.

PubMed

Koch, Konrad; Lippert, Thomas; Drewes, Jörg E

2017-11-01

The impact of the inoculum's origin on the methane yield in Biochemical Methane Potential (BMP) tests was investigated. The three most commonly applied inocula were chosen, originating from (i) a digester of a wastewater treatment plant, (ii) an agricultural biogas plant treating manure and energy crops, and (iii) a biowaste treatment plant. The performance of each inoculum was tested with four different substrates, namely sewage sludge, dried whole crop maize, food waste, and microcrystalline cellulose as a typical reference material. The results revealed that the choice of inoculum had no significant impact on the specific methane yield of the tested substrates except for cellulose. Still, the specific methane production rate was significantly influenced by the choice of the inoculum especially for sewage sludge, but also for food waste and cellulose, whereas it became clear that an inoculum adapted to a substrate is beneficial for a speedy digestion. Copyright © 2017 Elsevier Ltd. All rights reserved.

Towards a universal microbial inoculum for dissolved organic carbon degradation experiments

NASA Astrophysics Data System (ADS)

Pastor, Ada; Catalán, Núria; Gutiérrez, Carmen; Nagar, Nupur; Casas-Ruiz, Joan P.; Obrador, Biel; von Schiller, Daniel; Sabater, Sergi; Petrovic, Mira; Borrego, Carles M.; Marcé, Rafael

2017-04-01

Dissolved organic carbon (DOC) is the largest biologically available pool of organic carbon in aquatic ecosystems and its degradation along the land-to-ocean continuum has implications for carbon cycling from local to global scales. DOC biodegradability is usually assessed by incubating filtered water inoculated with native microbial assemblages in the laboratory. However, the use of a native inoculum from several freshwaters, without having a microbial-tailored design, hampers our ability to tease apart the relative contribution of the factors driving DOC degradation from the effects of local microbial communities. The use of a standard microbial inoculum would allow researchers to disentangle the drivers of DOC degradation from the metabolic capabilities of microbial communities operating in situ. With this purpose, we designed a bacterial inoculum to be used in experiments of DOC degradation in freshwater habitats. The inoculum is composed of six bacterial strains that easily grow under laboratory conditions, possess a versatile metabolism and are able to grow under both aerobic and anaerobic conditions. The mixed inoculum showed higher DOC degradation rates than those from their isolated bacterial components and the consumption of organic substrates was consistently replicated. Moreover, DOC degradation rates obtained using the designed inoculum were responsive across a wide range of natural water types differing in DOC concentration and composition. Overall, our results show the potential of the designed inoculum as a tool to discriminate between the effects of environmental drivers and intrinsic properties of DOC on degradation dynamics.

National validation study of a swab protocol for the recovery of Bacillus anthracis spores from surfaces.

PubMed

Hodges, Lisa R; Rose, Laura J; O'Connell, Heather; Arduino, Matthew J

2010-05-01

Twelve Laboratory Response Network (LRN) affiliated laboratories participated in a validation study of a macrofoam swab protocol for the recovery, detection, and quantification of viable B. anthracis (BA) Sterne spores from steel surfaces. CDC personnel inoculated steel coupons (26cm(2)) with 1-4 log(10) BA spores and recovered them by sampling with pre-moistened macrofoam swabs. Phase 1 (P1) of the study evaluated swabs containing BA only, while dust and background organisms were added to swabs in Phase 2 (P2) to mimic environmental conditions. Laboratories processed swabs and enumerated spores by culturing eluted swab suspensions and counting colonies with morphology consistent with BA. Processed swabs were placed in enrichment broth, incubated 24h, and cultured by streaking for isolation. Real-time PCR was performed on selected colonies from P2 samples to confirm the identity of BA. Mean percent recovery (%R) of spores from the surface ranged from 15.8 to 31.0% (P1) and from 27.9 to 55.0% (P2). The highest mean percent recovery was 31.0% (sd 10.9%) for P1 (4 log(10) inoculum) and 55.0% (sd 27.6%) for P2 (1 log(10) inoculum). The overall %R was higher for P2 (44.6%) than P1 (24.1%), but the overall reproducibility (between-lab variability) was lower in P2 than in P1 (25.0 vs 16.5%CV, respectively). The overall precision (within-lab variability) was close to identical for P1 and P2 (44.0 and 44.1, respectively), but varied greatly between inoculum levels. The protocol demonstrated linearity in %R over the three inoculum levels and is able to detect between 26 and 5x10(6)spores/26cm(2). Sensitivity as determined by culture was >98.3% for both phases and all inocula, suggesting that the culture method maintains sensitivity in the presence of contaminants. The enrichment broth method alone was less sensitive for sampled swabs (66.4%) during P2, suggesting that the presence of background organisms inhibited growth or isolation of BA from the broth. The addition of real-time PCR testing to the assay increased specificity from >85.4% to >95.0% in P2. Although the precision was low at the 1 log(10) inoculum level in both phases (59.0 and 50.2%), this swab processing protocol, was sensitive, specific, precise, and reproducible at 2-4 log(10)/26cm(2) spore concentrations. Published by Elsevier B.V.

An Outpatient, Ambulant-Design, Controlled Human Infection Model Using Escalating Doses of Salmonella Typhi Challenge Delivered in Sodium Bicarbonate Solution

PubMed Central

Waddington, Claire S.; Darton, Thomas C.; Jones, Claire; Haworth, Kathryn; Peters, Anna; John, Tessa; Thompson, Ben A. V.; Kerridge, Simon A.; Kingsley, Robert A.; Zhou, Liqing; Holt, Kathryn E.; Yu, Ly-Mee; Lockhart, Stephen; Farrar, Jeremy J.; Sztein, Marcelo B.; Dougan, Gordon; Angus, Brian; Levine, Myron M.; Pollard, Andrew J.

2014-01-01

Background. Typhoid fever is a major global health problem, the control of which is hindered by lack of a suitable animal model in which to study Salmonella Typhi infection. Until 1974, a human challenge model advanced understanding of typhoid and was used in vaccine development. We set out to establish a new human challenge model and ascertain the S. Typhi (Quailes strain) inoculum required for an attack rate of 60%–75% in typhoid-naive volunteers when ingested with sodium bicarbonate solution. Methods. Groups of healthy consenting adults ingested escalating dose levels of S. Typhi and were closely monitored in an outpatient setting for 2 weeks. Antibiotic treatment was initiated if typhoid diagnosis occurred (temperature ≥38°C sustained ≥12 hours or bacteremia) or at day 14 in those remaining untreated. Results. Two dose levels (103 or 104 colony-forming units) were required to achieve the primary objective, resulting in attack rates of 55% (11/20) or 65% (13/20), respectively. Challenge was well tolerated; 4 of 40 participants fulfilled prespecified criteria for severe infection. Most diagnoses (87.5%) were confirmed by blood culture, and asymptomatic bacteremia and stool shedding of S. Typhi was also observed. Participants who developed typhoid infection demonstrated serological responses to flagellin and lipopolysaccharide antigens by day 14; however, no anti-Vi antibody responses were detected. Conclusions. Human challenge with a small inoculum of virulent S. Typhi administered in bicarbonate solution can be performed safely using an ambulant-model design to advance understanding of host–pathogen interactions and immunity. This model should expedite development of diagnostics, vaccines, and therapeutics for typhoid control. PMID:24519873

Detection methods for human enteric viruses in representative foods.

PubMed

Leggitt, P R; Jaykus, L A

2000-12-01

Although viral foodborne disease is a significant problem, foods are rarely tested for viral contamination, and when done, testing is limited to shellfish commodities. In this work, we report a method to extract and detect human enteric viruses from alternative food commodities using an elution-concentration approach followed by detection using reverse transcription-polymerase chain reaction (RT-PCR). Fifty-gram lettuce or hamburger samples were artificially inoculated with poliovirus type 1 (PV1), hepatitis A virus (HAV), or the Norwalk virus and processed by the sequential steps of homogenization, filtration, Freon extraction (hamburger), and polyethylene glycol (PEG) precipitation. To reduce volumes further and remove RT-PCR inhibitors, a secondary PEG precipitation was necessary, resulting in an overall 10- to 20-fold sample size reduction from 50 g to 3 to 5 ml. Virus recoveries in secondary PEG concentrates ranged from 10 to 70% for PV1 and 2 to 4% for HAV as evaluated by mammalian cell culture infectivity assay. Total RNA from PEG concentrates was extracted to a small volume (30 to 40 microl) and subjected to RT-PCR amplification of viral RNA sequences. Detection limit studies indicated that viral RNA was consistently detected by RT-PCR at initial inoculum levels > or =102 PFU/50-g food sample for PV1 and > or =10(3) PFU/50-g food sample for HAV. In similar studies with the Norwalk virus, detection at inoculum levels > or =1.5 X 10(3) PCR-amplifiable units/50-g sample for both food products was possible. All RT-PCR amplicons were confirmed by subsequent Southern hybridization. The procedure reported represents progress toward the development of methods to detect human enteric viral contamination in foods other than shellfish.

Fiber Treatment Effects on Bioreactor Bulk Fluid Trends

NASA Technical Reports Server (NTRS)

Ellis, Ronald II

2013-01-01

In order to facilitate the exploration of worlds beyond the borders of our planet, it is necessary to maintain sustainable levels of clean water. The remediation of water via Membrane Aerated Bioreactors (MABRs) is one such method, and the focus of this study. MARRs rely on healthy biofilms grown on hollow fiber membranes to clean non-potable water. These biofilms can take weeks to months to establish. Therefore, various fiber treatments and two inoculums were evaluated for their effect on rapid biofilm formation. Fiber treatments are as follows: sanding of the fibers with 1500 and 8000 grit sandpaper, immersion of the fibers in a 1% hydrofluoric acid solution for 12 seconds and 15 minutes, and the immersion of the fibers in a Fluoroetch® solution for 18 seconds and 5 minutes. The two inoculums utilized were sourced from healthy, established MARRs; Texas Tech University (TTU) MABR "TRL5" and Kennedy Space Center (KSC) MABR "R3". Data attained from direct bacterial cell counts of the reactor bulk fluids via fluorescent microscopy, suggests that the fluoroetching treatment combined with the TTU inoculum show the greatest biofilm creation.

Effect of seed sludge on characteristics and microbial community of aerobic granular sludge.

PubMed

Song, Zhiwei; Pan, Yuejun; Zhang, Kun; Ren, Nanqi; Wang, Aijie

2010-01-01

Aerobic granular sludge was cultivated by using different kinds of seed sludge in sequencing batch airlift reactor. The influence of seed sludge on physical and chemical properties of granular sludge was studied; the microbial community structure was probed by using scanning electron microscope and polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). The results showed that seed sludge played an important role on the formation of aerobic granules. Seed sludge taken from beer wastewater treatment plant (inoculum A) was more suitable for cultivating aerobic granules than that of sludge from municipal wastewater treatment plant (inoculum B). Cultivated with inoculum A, large amount of mature granules formed after 35 days operation, its SVI reached 32.75 mL/g, and SOUR of granular sludge was beyond 1.10 mg/(g x min). By contrast, it needed 56 days obtaining mature granules using inoculum B. DGGE profiles indicated that the dominant microbial species in mature granules were 18 and 11 OTU when inoculum A and B were respectively employed as seed sludge. The sequencing results suggested that dominant species in mature granules cultivated by inoculum A were Paracoccus sp., Devosia hwasunensi, Pseudoxanthomonas sp., while the dominant species were Lactococcus raffinolactis and Pseudomonas sp. in granules developed from inoculum B.

Assessing the Challenges in the Application of Potential Probiotic Lactic Acid Bacteria in the Large-Scale Fermentation of Spanish-Style Table Olives

PubMed Central

Rodríguez-Gómez, Francisco; Romero-Gil, Verónica; Arroyo-López, Francisco N.; Roldán-Reyes, Juan C.; Torres-Gallardo, Rosa; Bautista-Gallego, Joaquín; García-García, Pedro; Garrido-Fernández, Antonio

2017-01-01

This work studies the inoculation conditions for allowing the survival/predominance of a potential probiotic strain (Lactobacillus pentosus TOMC-LAB2) when used as a starter culture in large-scale fermentations of green Spanish-style olives. The study was performed in two successive seasons (2011/2012 and 2012/2013), using about 150 tons of olives. Inoculation immediately after brining (to prevent wild initial microbiota growth) followed by re-inoculation 24 h later (to improve competitiveness) was essential for inoculum predominance. Processing early in the season (September) showed a favorable effect on fermentation and strain predominance on olives (particularly when using acidified brines containing 25 L HCl/vessel) but caused the disappearance of the target strain from both brines and olives during the storage phase. On the contrary, processing in October slightly reduced the target strain predominance on olives (70–90%) but allowed longer survival. The type of inoculum used (laboratory vs. industry pre-adapted) never had significant effects. Thus, this investigation discloses key issues for the survival and predominance of starter cultures in large-scale industrial fermentations of green Spanish-style olives. Results can be of interest for producing probiotic table olives and open new research challenges on the causes of inoculum vanishing during the storage phase. PMID:28567038

Study on Leucaena leocochepala seed during fermentation : sensory characteristic and changes on anti nutritional compounds and mimosine level

NASA Astrophysics Data System (ADS)

Nursiwi, A.; Ishartani, D.; Sari, AM; Nisyah, K.

2018-01-01

Lamtoro (Leucaena leucocephala) seed is one of the leguminosae which have high level of protein but it contains toxic compound such as mimosine and some anti nutritional compounds such as phitic acid and tannin. The objectives of the research was to investigate the sensory characteristic and the changes onanti nutritional compounds and mimosine level in Leucaena leucochepala seed during fermentation. Lamtoro tempeh processing was carried out by boiling the seed, crushing to separate the hull, soaking, boiling, and fermentation. The best concentration inoculum in lamtoro tempeh processing was determined by hedonic test. Fermentation was carried out in 36 hours and every 6 hours mimosine, tannin, and phitic acid content was analyzed. From hedonic test, inoculum concentration of 1% was used in lamtoro tempeh processing. During 36 hours fermentation, phytic acid content and mimosine content was decreased significantly, from 0.0558 % to 0.0453 % and from 0.00393 % to 0.00173 % respectively. Whereas tannin content was increased signifacantly, from 0.0822 % to 0.00173 %.

Why is Puccinia graminis f. sp. tritici, but not P. striiformis f. sp. tritici able to infect an alternate host in the U.S. Pacific Northwest

USDA-ARS?s Scientific Manuscript database

Sexual reproduction of the stem rust pathogen, Puccinia graminis f. sp. tritici (Pgt), on barberry (Berberis vulgaris) has been shown to provide initial inoculum for the development of the disease on wheat and barley and also generate diverse races of the pathogen. However, in our previous study, t...

Stochastic Assembly of Bacteria in Microwell Arrays Reveals the Importance of Confinement in Community Development

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hansen, Ryan H.; Timm, Andrea C.; Timm, Collin M.

The structure, function and evolving composition of microbial communities is deeply influenced by the physical and chemical architecture of the local microenvironment. The complexity of this parameter space in naturally occurring systems has made a clear understanding of the key drivers of community development elusive. Here, we examine the role of spatial confinement on community development using a microwell platform that allows for assembly and monitoring of unique microbial communities en masse. This platform was designed to contain microwells with varied size features in order to mimic various levels of spatial confinement found in natural systems. Microbial populations assembled inmore » wells with incrementally smaller size features showed increasingly larger variations in inoculum levels. By exploiting this size dependence, large wells were used to assemble homogenous initial populations of Pseudomonas aeruginosa, allowing for reproducible, directed growth trajectories. In contrast, smaller wells were used to assemble a heterogeneous range of initial populations, resulting in a variety of growth and decay trajectories. This allowed for parallel screening of single member communities across different levels of confinement to identify initial conditions in which P. aeruginosa colonies have dramatically higher probabilities of survival. These results demonstrate a unique approach for manipulating the distribution of initial microbial populations assembled into controlled microenvironments to rapidly identify population and environmental parameters conducive or inhibitive to growth. Additionally, multi-member community assembly was characterized to demonstrate the power of this platform for studying the role of member abundance on microbial competition, mutualism and community succession.« less

Stochastic Assembly of Bacteria in Microwell Arrays Reveals the Importance of Confinement in Community Development

DOE PAGES

Hansen, Ryan H.; Timm, Andrea C.; Timm, Collin M.; ...

2016-05-06

The structure, function and evolving composition of microbial communities is deeply influenced by the physical and chemical architecture of the local microenvironment. The complexity of this parameter space in naturally occurring systems has made a clear understanding of the key drivers of community development elusive. Here, we examine the role of spatial confinement on community development using a microwell platform that allows for assembly and monitoring of unique microbial communities en masse. This platform was designed to contain microwells with varied size features in order to mimic various levels of spatial confinement found in natural systems. Microbial populations assembled inmore » wells with incrementally smaller size features showed increasingly larger variations in inoculum levels. By exploiting this size dependence, large wells were used to assemble homogenous initial populations of Pseudomonas aeruginosa, allowing for reproducible, directed growth trajectories. In contrast, smaller wells were used to assemble a heterogeneous range of initial populations, resulting in a variety of growth and decay trajectories. This allowed for parallel screening of single member communities across different levels of confinement to identify initial conditions in which P. aeruginosa colonies have dramatically higher probabilities of survival. These results demonstrate a unique approach for manipulating the distribution of initial microbial populations assembled into controlled microenvironments to rapidly identify population and environmental parameters conducive or inhibitive to growth. Additionally, multi-member community assembly was characterized to demonstrate the power of this platform for studying the role of member abundance on microbial competition, mutualism and community succession.« less

Rhizoctonia solani infection reduced by bacterial and fungal combination of biofertilizer inoculums on organic potato

NASA Astrophysics Data System (ADS)

Papp, Orsolya; Biro, Borbala; Abod, Eva; Jung, Timea; Tirczka, Imre; Drexler, Dora

2017-04-01

Soil biological functioning and proper agrotechnical management are of key importance in organic agriculture. Beneficial microbial inoculums are used either as plant strengthening products (psp) or also as plant protecting products (ppp). Question is, which type of microbes should be applied to certain soil-plant systems to improve yield or reduce the damage of soil-born plant pathogens? Objective of present study was to compare the effect of inoculums 1 (PPS) with plant growth promoting bacterium strains (PGPR) and inoculums 2 (TPB) with potential biocontrol-agents, including both fungi and bacteria in organic potato production. Field experiment was conducted at the Organic Research Station of the Szent István University (Babatpuszta, Hungary). Growth and quality of potato (Solanum tuberosum var. Demon) was studied in the two microbial treatments and control, in four replicates. The PPS inoculums included Pseudomonas protegens, Ps. jessenii and Strenotrophomonas maltophylia, with plant growth promoting (PGPR) effect. TPB inoculums consisted of Trichoderma hartianum, Pseudomonas putida and Bacillus subtilis strains with main biocontrol effects of fungal and bacterium combination. Strains were incubated for 24 hours at 28 oC in a rotary shaker (140 rpm/min) up till cell-number about 1010 cell.ml-1 in Nutrient broth substrate, and mixed to prepare combined inoculums. Each potato tuber was treated by 10 ml inoculums that was added to 100 ml water respectively with only water at the controls. Yield of potato (10 plants/plot) and tuber quality, i.e. the percentage ratio of scabbiness (Streptomyces scabies), Rhizoctonia solani, and Fusarium sp. infection was estimated. Abundance of total aerob and anaerob heterotrophs, total microscopic fungi, pseudomonads bacteria and some sporeforming microorganisms was assessed by the most probable number (MPN) method in soil samples, collected four times during vegetation. Soil enzyme, dehydrogenase (DH) and fluorescein diacetate (FDA) activity was estimated, beside soil physical and chemical characteristics. Statistics, including binomial logistic regression was used for evaluation (IBM SPSS Statistics 22 software). Aerobic MPN counts were reduced by 0,5 value, anaerobic however were increased by 2 order of magnitude at the end of vegetation period. Both inoculums reduced the fungal counts at 60% of flowering stage, but PPS inoculums improved also the abundance of pseudomonads bacteria in the soil at all sampling stages. Soil dehydrogenase (DH) activity showed a strong seasonal variability, which was about 20-times higher at flowering of potato, more particularly at TPB inoculums. Although yield parameters were only tendentiously improved, the presence of Rhizoctonia solani infected tubers was significantly less likely (by 70,3%) with TPB inoculums combination. We assumed that presence of biocontrol type of Trichoderma fungi in TPB inoculums was the reason for such a significant reduction of Rhizoctonia infection. Necessity of previous monitoring of soil-health, including the microbial status of potential biocontrol strains is concluded. The tuber quality of organic potato may be enhanced by using the inoculums tested in this study. Thematically belongs to Biochar (Piac-13-1-2013-0274) and Biofector (GA 312117) projects.

Influence of the hot-fill water-spray-cooling process after continuous pasteurization on the number of decimal reductions and on Alicyclobacillus acidoterrestris CRA 7152 growth in orange juice stored at 35 degrees C.

PubMed

Spinelli, Ana Cláudia N F; Sant'Ana, Anderson S; Pacheco-Sanchez, Cristiana P; Massaguer, Pilar R

2010-02-28

In this study, the influence of the hot-fill water-spray-cooling process after continuous pasteurization on the number of decimal reductions (gamma) and growth parameters (lag time; lambda, ratio N(f)/N(o); kappa, maximum growth rate; mu) of Alicyclobacillus acidoterrestris CRA 7152 in orange juice stored at 35 degrees C were investigated. Two different inoculum levels of A. acidoterrestris CRA 7152 (10(2) and 10(3) spores/mL) in orange juice (11(0)Brix, pH 3.7) and a Microthermics UHT-HTST pilot plant were used to simulate industrial conditions. Results have shown that regardless of the inoculum level (10(2) or 10(3) spores/mL), the pasteurization processes were unable to cause even 1 gamma. Predictive modeling using the Baranyi model showed that only kappa and time to reach 10(4)spores/mL (t10(4) - time to juice spoilage) were affected by the spore inoculum used (p<0.05). It has been concluded that A. acidoterrestris was able to survive the hot-fill process and to grow and spoil orange juice in 5-6 days when the final storage temperature was 35 degrees C. (c) 2009 Elsevier B.V. All rights reserved.

Forest type influences transmission of Phytophthora ramorum in California oak woodlands.

PubMed

Davidson, Jennifer M; Patterson, Heather A; Wickland, Allison C; Fichtner, Elizabeth J; Rizzo, David M

2011-04-01

The transmission ecology of Phytophthora ramorum from bay laurel (Umbellularia californica) leaves was compared between mixed-evergreen and redwood forest types throughout winter and summer disease cycles in central, coastal California. In a preliminary multisite study, we found that abscission rates of infected leaves were higher at mixed-evergreen sites. In addition, final infection counts were slightly higher at mixed-evergreen sites or not significantly different than at redwood sites, in part due to competition from other foliar pathogens at redwood sites. In a subsequent, detailed study of paired sites where P. ramorum was the main foliar pathogen, summer survival of P. ramorum in bay laurel leaves was lower in mixed-evergreen forest due to lower recovery from infected attached leaves and higher abscission rates of infected leaves. Onset of inoculum production and new infections of bay laurel leaves occurred later in mixed-evergreen forest. Mean inoculum levels in rainwater and final infection counts on leaves were higher in redwood forest. Based on these two studies, lower summer survival of reservoir inoculum in bay laurel leaves in mixed-evergreen forest may result in delayed onset of both inoculum production and new infections, leading to slower disease progress in the early rainy season compared with redwood forest. Although final infection counts also will depend on other foliar pathogens and disease history, in sites where P. ramorum is the main foliar pathogen, these transmission patterns suggest higher rates of disease spread in redwood forests during rainy seasons of short or average length.

Bioremediation of fungicides by spent mushroom substrate and its associated microflora.

PubMed

Ahlawat, O P; Gupta, Pardeep; Kumar, Satish; Sharma, D K; Ahlawat, K

2010-10-01

Experiments were conducted both under in vitro and in situ conditions to determine the biodegradation potential of button mushroom spent substrate (SMS) and its dominating microbes (fungi and bacteria) for carbendazim and mancozeb, the commonly used agricultural fungicides. During 6 days of incubation at 30 ± 2°C under broth culture conditions, highest degradation of carbendazim (17.45%) was recorded with B-1 bacterial isolate, while highest degradation of mancozeb (18.05%) was recorded with Trichoderma sp. In fungicide pre-mixed sterilized SMS, highest degradation of carbendazim (100.00-66.50 μg g(-1)) was recorded with mixed inoculum of Trichoderma sp. and Aspergillus sp., whereas highest degradation of mancozeb (100.00-50.50 μg g(-1)) was with mixed inoculum of Trichoderma sp., Aspergillus sp. and B-I bacterial isolate in 15 days of incubation at 30 ± 2°C. All these microbes both individually as well as in different combinations grew well and produced extracellular lignolytic enzymes on SMS, which helped in fungicides degradation. Under in situ conditions, among three different proportions of SMS (10, 20 and 30%, w/w) mixed with fungicide pre-mixed soil (100 μg g(-1) of soil), the degradation of carbendazim was highest in 30% SMS treatment, while for mancozeb it was in 20% SMS treatment. The residue levels of both fungicides decreased to half of their initial concentration after 1 month of SMS mixing.

Enhanced anaerobic digestion performance via combined solids- and leachate-based hydrolysis reactor inoculation.

PubMed

Wilson, L Paige; Sharvelle, Sybil E; De Long, Susan K

2016-11-01

Suboptimal conditions in anaerobic digesters (e.g., presence of common inhibitors ammonia and salinity) limit waste hydrolysis and lead to unstable performance and process failures. Application of inhibitor-tolerant inocula improves hydrolysis, but approaches are needed to establish and maintain these desired waste-hydrolyzing bacteria in high-solids reactors. Herein, performance was compared for leach bed reactors (LBRs) seeded with unacclimated or acclimated inoculum (0-60% by mass) at start-up and over long-term operation. High quantities of inoculum (∼60%) increase waste hydrolysis and are beneficial at start-up or when inhibitors are increasing. After start-up (∼112days) with high inoculum quantities, leachate recirculation leads to accumulation of inhibitor-tolerant hydrolyzing bacteria in leachate. During long-term operation, low inoculum quantities (∼10%) effectively increase waste hydrolysis relative to without solids-derived inoculum. Molecular analyses indicated that combining digested solids with leachate-based inoculum doubles quantities of Bacteria contacting waste over a batch and supplies additional desirable phylotypes Bacteriodes and Clostridia. Copyright © 2016 Elsevier Ltd. All rights reserved.

Reduction of Escherichia coli O157:H7 viability on leafy green vegetables by treatment with a bacteriophage mixture and trans-cinnamaldehyde.

PubMed

Viazis, Stelios; Akhtar, Mastura; Feirtag, Joellen; Diez-Gonzalez, Francisco

2011-02-01

Enterohemorrhagic Escherichia coli (EHEC) O157:H7 has been recognized as a major foodborne pathogen responsible for frequent gastroenteritis outbreaks. Phages and essential oils can be used as a natural antimicrobial method to reduce bacterial pathogens from the food supply. The objective of this study was to determine the effect of a bacteriophage cocktail, BEC8, alone and in combination with the essential oil trans-cinnameldehyde (TC) on the viability of a mixture of EHEC O157:H7 strains applied on whole baby romaine lettuce and baby spinach leaves. The EHEC O157:H7 strains used were Nal(R) mutants of EK27, ATCC 43895, and 472. Exponentially growing cells from tryptic soy (TS) broth cultures were spot inoculated on leaves and dried. EHEC cells were placed at low, medium, and high inoculum levels (10(4), 10(5), and 10(6) CFU/mL, respectively). Appropriate controls, BEC8 (approx. 10(6) PFU/leaf), and TC (0.5% v/v) were applied on treated leaves. The leaves were incubated at 4, 8, 23, and 37 °C in Petri dishes with moistened filter papers. EHEC survival was determined using standard plate count on nalidixic acid (50 μg/mL) Sorbitol MacConkey agar. No survivors were detected when both leaves were treated with BEC8 or TC individually at low inoculum levels after 24 h at 23 and 37 °C. When the EHEC inoculum size increased and/or incubation temperature decreased, the efficacy of BEC8 and TC decreased. However, when the two treatments were combined, no survivors were detected after 10 min at all temperatures and inoculum levels on both leafy greens. These results indicated that the BEC8/TC combination was highly effective against EHEC on both leafy greens. This combination could potentially be used as an antimicrobial to inactivate EHEC O157:H7 and reduce their incidence in the food chain. Copyright © 2010 Elsevier Ltd. All rights reserved.

Fermentation of Ammonia Fiber Expansion Treated and Untreated Barley Straw in a Rumen Simulation Technique Using Rumen Inoculum from Cattle with Slow versus Fast Rate of Fiber Disappearance.

PubMed

Griffith, Candace L; Ribeiro, Gabriel O; Oba, Masahito; McAllister, Tim A; Beauchemin, Karen A

2016-01-01

The purpose of this study was to determine the effect of rumen inoculum from heifers with fast vs. slow rate of in situ fiber digestion on the fermentation of complex versus easily digested fiber sources in the forms of untreated and Ammonia Fiber Expansion (AFEX) treated barley straw, respectively, using an artificial rumen simulation technique (Rusitec). In situ fiber digestion was measured in a previous study by incubating untreated barley straw in the rumen of 16 heifers fed a diet consisting of 700 g/kg barley straw and 300 g/kg concentrate. The two heifers with fastest rate of digestion (Fast ≥ 4.18% h -1 ) and the two heifers with the slowest rate of digestion (Slow ≤ 3.17% h -1 ) were chosen as inoculum donors for this study. Two Rusitec apparatuses each equipped with eight fermenters were used in a completely randomized block design with two blocks (apparatus) and four treatments in a 2 × 2 factorial arrangement of treatments (Fast or Slow rumen inoculum and untreated or AFEX treated straw). Fast rumen inoculum and AFEX straw both increased ( P < 0.05) disappearance of dry matter (DMD), organic matter, true DMD, neutral detergent fiber, acid detergent fiber, and nitrogen (N) with an interactive effect between the two ( P < 0.05). Fast rumen inoculum increased ( P > 0.05) methane production per gram of digested material for both untreated and AFEX straw, and reduced (interaction, P < 0.05) acetate: propionate ratio for untreated straw. Greater relative populations of Ruminococcus albus ( P < 0.05) and increased microbial N production ( P = 0.045) were observed in Fast rumen inoculum. AFEX straw in Fast inoculum had greater total bacterial populations than Slow, but for untreated straw this result was reversed (interaction, P = 0.013). These findings indicate that differences in microbial populations in rumen fluid contribute to differences in the capacity of rumen inoculum to digest fiber.

Disease spread across multiple scales in a spatial hierarchy: effect of host spatial structure and of inoculum quantity and distribution.

PubMed

Gosme, Marie; Lucas, Philippe

2009-07-01

Spatial patterns of both the host and the disease influence disease spread and crop losses. Therefore, the manipulation of these patterns might help improve control strategies. Considering disease spread across multiple scales in a spatial hierarchy allows one to capture important features of epidemics developing in space without using explicitly spatialized variables. Thus, if the system under study is composed of roots, plants, and planting hills, the effect of host spatial pattern can be studied by varying the number of plants per planting hill. A simulation model based on hierarchy theory was used to simulate the effects of large versus small planting hills, low versus high level of initial infections, and aggregated versus uniform distribution of initial infections. The results showed that aggregating the initially infected plants always resulted in slower epidemics than spreading out the initial infections uniformly. Simulation results also showed that, in most cases, disease epidemics were slower in the case of large host aggregates (100 plants/hill) than with smaller aggregates (25 plants/hill), except when the initially infected plants were both numerous and spread out uniformly. The optimal strategy for disease control depends on several factors, including initial conditions. More importantly, the model offers a framework to account for the interplay between the spatial characteristics of the system, rates of infection, and aggregation of the disease.

Survival of Salmonella Typhimurium in poultry-based meat preparations during grilling, frying and baking.

PubMed

Roccato, Anna; Uyttendaele, Mieke; Cibin, Veronica; Barrucci, Federica; Cappa, Veronica; Zavagnin, Paola; Longo, Alessandra; Ricci, Antonia

2015-03-16

The burden of food-borne diseases still represents a threat to public health; in 2012, the domestic setting accounted for 57.6% of strong-evidence EU food-borne Salmonella outbreaks. Next to cross-contamination, inadequate cooking procedure is considered as one of the most important factors contributing to food-borne illness. The few studies which have assessed the effect of domestic cooking on the presence and numbers of pathogens in different types of meat have shown that consumer-style cooking methods can allow bacteria to survive and that the probability of eating home-cooked poultry meat that still contains surviving bacteria after heating is higher than previously assumed. Thus, the main purpose of this study was to reproduce and assess the effect of several types of cooking treatments (according to label instructions and not following label instructions) on the presence and numbers of Salmonella Typhimurium DT 104 artificially inoculated in five types of poultry-based meat preparations (burgers, sausages, ready-to-cook-kebabs, quail roulades and extruded roulades) that are likely to be contaminated by Salmonella. Three contamination levels (10 cfu/g; 100 cfu/g and 1000 cfu/g) and three cooking techniques (grilling, frying and baking) were applied. Cooking treatments performed according to label instructions eliminated Salmonella Typhimurium (absence per 25g) for contamination levels of 10 and 100 cfu/g but not for contamination levels of 1000 cfu/g. After improper cooking, 26 out of 78 samples were Salmonella-positive, and 23 out of these 26 samples were artificially contaminated with bacterial loads between 100 and 1000 cfu/g. Nine out of 26 samples provided quantifiable results with a minimum level of 1.4MPN/g in kebabs (initial inoculum level: 100 cfu/g) after grilling and a maximum level of 170MPN/g recorded in sausages (initial inoculum level: 1000 cfu/g) after grilling. Kebabs were the most common Salmonella-positive meat product after cooking, followed by sausages, burgers and extruded roulades; in relation to the type of cooking treatment applied, Salmonella Typhimurium was detected mostly after frying. Thus, following label instructions mostly, but not always, produced safe cooked poultry-based meat preparations, while the application of inadequate cooking treatments was not able to assure complete elimination of Salmonella from the products even with a low contamination level (10cfu/g). Consequently, there is a need to develop guidelines for producers and consumers and promote a multidisciplinary educational campaign in order to provide information on safe cooking and time-temperature combinations able to maintain the organoleptic qualities of meat. Copyright © 2014 Elsevier B.V. All rights reserved.

A rapid culture system uninfluenced by an inoculum effect increases reliability and convenience for drug susceptibility testing of Mycobacterium tuberculosis.

PubMed

Jung, Yong-Gyun; Kim, Hyejin; Lee, Sangyeop; Kim, Suyeoun; Jo, EunJi; Kim, Eun-Geun; Choi, Jungil; Kim, Hyun Jung; Yoo, Jungheon; Lee, Hye-Jeong; Kim, Haeun; Jung, Hyunju; Ryoo, Sungweon; Kwon, Sunghoon

2018-06-05

The Disc Agarose Channel (DAC) system utilizes microfluidics and imaging technologies and is fully automated and capable of tracking single cell growth to produce Mycobacterium tuberculosis (MTB) drug susceptibility testing (DST) results within 3~7 days. In particular, this system can be easily used to perform DSTs without the fastidious preparation of the inoculum of MTB cells. Inoculum effect is one of the major problems that causes DST errors. The DAC system was not influenced by the inoculum effect and produced reliable DST results. In this system, the minimum inhibitory concentration (MIC) values of the first-line drugs were consistent regardless of inoculum sizes ranging from ~10 3 to ~10 8 CFU/mL. The consistent MIC results enabled us to determine the critical concentrations for 12 anti-tuberculosis drugs. Based on the determined critical concentrations, further DSTs were performed with 254 MTB clinical isolates without measuring an inoculum size. There were high agreement rates (96.3%) between the DAC system and the absolute concentration method using Löwenstein-Jensen medium. According to these results, the DAC system is the first DST system that is not affected by the inoculum effect. It can thus increase reliability and convenience for DST of MTB. We expect that this system will be a potential substitute for conventional DST systems.

Synergism of Cattle and Bison Inoculum on Ruminal Fermentation and Select Bacterial Communities in an Artificial Rumen (Rusitec) Fed a Barley Straw Based Diet.

PubMed

Oss, Daniela B; Ribeiro, Gabriel O; Marcondes, Marcos I; Yang, WenZhu; Beauchemin, Karen A; Forster, Robert J; McAllister, Tim A

2016-01-01

This study evaluated the effect of increasing the proportion of bison relative to cattle inoculum on fermentation and microbial populations within an artificial rumen (Rusitec). The experiment was a completely randomized design with a factorial treatment structure (proportion cattle:bison inoculum; 0:100, 33:67, 67:33, and 100:0) replicated in two Rusitec apparatuses ( n = 8 fermenters). The experiment was 15 d with 8 d of adaptation and 7 d of sampling. Fermenters were fed a diet of 70:30 barley straw:concentrate (DM basis). True digestibility of DM was determined after 48 h of incubation from d 13 to 15, and daily ammonia (NH 3 ) and volatile fatty acid (VFA) production were measured on d 9-12. Protozoa counts were determined at d 9, 11, 13, and 15 and particle-associated bacteria (PAB) from d 13 to 15. Select bacterial populations in the PAB were measured using RT-qPCR. Fermenter was considered the experimental unit and day of sampling as a repeated measure. Increasing the proportion of bison inoculum resulted in a quadratic effect ( P < 0.05) on straw, concentrate and total true DM disappearance and on straw and total neutral detergent fiber (aNDF) disappearance, with greater disappearances observed with mixed inoculum. There were no effect of source or proportion of inoculum on ADF disappearance ( P > 0.05). Increasing bison inoculum linearly increased ( P < 0.05) concentrate aNDF disappearance, total and concentrate N disappearance as well as total daily VFA and acetate production. A positive quadratic response ( P < 0.05) was observed for daily NH 3 -N, propionate, butyrate, valerate, isovalerate and isobutyrate production, as well as the acetate:propionate ratio. Increasing the proportion of bison inoculum linearly increased ( P < 0.05) total protozoa numbers. No effects were observed on pH, total gas and methane production, microbial N synthesis, or copies of 16S rRNA associated with total bacteria, Selenomonas ruminantium or Prevotella bryantii . Increasing bison inoculum had a quadratic effect ( P < 0.05) on Fibrobacter succinogenes , and tended to linearly ( P < 0.10) increase Ruminococcus flavefaciens and decrease ( P < 0.05) Ruminococcus albus copy numbers. In conclusion, bison inoculum increased the degradation of feed protein and fiber. A mixture of cattle and bison rumen inoculum acted synergistically, increasing the DM and aNDF disappearance of barley straw.

Synergism of Cattle and Bison Inoculum on Ruminal Fermentation and Select Bacterial Communities in an Artificial Rumen (Rusitec) Fed a Barley Straw Based Diet

PubMed Central

Oss, Daniela B.; Ribeiro, Gabriel O.; Marcondes, Marcos I.; Yang, WenZhu; Beauchemin, Karen A.; Forster, Robert J.; McAllister, Tim A.

2016-01-01

This study evaluated the effect of increasing the proportion of bison relative to cattle inoculum on fermentation and microbial populations within an artificial rumen (Rusitec). The experiment was a completely randomized design with a factorial treatment structure (proportion cattle:bison inoculum; 0:100, 33:67, 67:33, and 100:0) replicated in two Rusitec apparatuses (n = 8 fermenters). The experiment was 15 d with 8 d of adaptation and 7 d of sampling. Fermenters were fed a diet of 70:30 barley straw:concentrate (DM basis). True digestibility of DM was determined after 48 h of incubation from d 13 to 15, and daily ammonia (NH3) and volatile fatty acid (VFA) production were measured on d 9–12. Protozoa counts were determined at d 9, 11, 13, and 15 and particle-associated bacteria (PAB) from d 13 to 15. Select bacterial populations in the PAB were measured using RT-qPCR. Fermenter was considered the experimental unit and day of sampling as a repeated measure. Increasing the proportion of bison inoculum resulted in a quadratic effect (P < 0.05) on straw, concentrate and total true DM disappearance and on straw and total neutral detergent fiber (aNDF) disappearance, with greater disappearances observed with mixed inoculum. There were no effect of source or proportion of inoculum on ADF disappearance (P > 0.05). Increasing bison inoculum linearly increased (P < 0.05) concentrate aNDF disappearance, total and concentrate N disappearance as well as total daily VFA and acetate production. A positive quadratic response (P < 0.05) was observed for daily NH3-N, propionate, butyrate, valerate, isovalerate and isobutyrate production, as well as the acetate:propionate ratio. Increasing the proportion of bison inoculum linearly increased (P < 0.05) total protozoa numbers. No effects were observed on pH, total gas and methane production, microbial N synthesis, or copies of 16S rRNA associated with total bacteria, Selenomonas ruminantium or Prevotella bryantii. Increasing bison inoculum had a quadratic effect (P < 0.05) on Fibrobacter succinogenes, and tended to linearly (P < 0.10) increase Ruminococcus flavefaciens and decrease (P < 0.05) Ruminococcus albus copy numbers. In conclusion, bison inoculum increased the degradation of feed protein and fiber. A mixture of cattle and bison rumen inoculum acted synergistically, increasing the DM and aNDF disappearance of barley straw. PMID:28018336

Prediction of phycoremediation of As(III) and As(V) from synthetic wastewater by Chlorella pyrenoidosa using artificial neural network

NASA Astrophysics Data System (ADS)

Podder, M. S.; Majumder, C. B.

2017-11-01

An artificial neural network (ANN) model was developed to predict the phycoremediation efficiency of Chlorella pyrenoidosa for the removal of both As(III) and As(V) from synthetic wastewater based on 49 data-sets obtained from experimental study and increased the data using CSCF technique. The data were divided into training (60%) validation (20%) and testing (20%) sets. The data collected was used for training a three-layer feed-forward back propagation (BP) learning algorithm having 4-5-1 architecture. The model used tangent sigmoid transfer function at input to hidden layer ( tansing) while a linear transfer function ( purelin) was used at output layer. Comparison between experimental results and model results gave a high correlation coefficient (R allANN 2 equal to 0.99987 for both ions and exhibited that the model was able to predict the phycoremediation of As(III) and As(V) from wastewater. Experimental parameters influencing phycoremediation process like pH, inoculum size, contact time and initial arsenic concentration [either As(III) or As(V)] were investigated. A contact time of 168 h was mainly required for achieving equilibrium at pH 9.0 with an inoculum size of 10% (v/v). At optimum conditions, metal ion uptake enhanced with increasing initial metal ion concentration.

Isolate resistance of Blastocystis hominis to metronidazole.

PubMed

Haresh, K; Suresh, K; Khairul Anus, A; Saminathan, S

1999-04-01

Isolates of Blastocystis hominis from infected immigrant workers from Indonesia, Bangladesh and infected individuals from Singapore and Malaysia were assessed for growth pattern and degree of resistance to different concentrations of metronidazole. Viability of the cells was assessed using eosin-brillian cresyl blue which stained viable cells green and nonviable cells red. The Bangladeshi and Singaporean isolates were nonviable even at the lowest concentration of 0.01 mg/ml, whereas 40% of the initial inoculum of parasites from the Indonesian isolate at day one were still viable in cultures with 1.0 mg/ml metronidazole. The study shows that isolates of B. hominis of different geographical origin have different levels of resistance to metronidazole. The search for more effective drugs to eliminate th parasite appears inevitable, especially since surviving parasites from metronidazole cultures show greater ability to multiply in subcultures than controls.

Implications of Bt traits on mycotoxin contamination in maize: Overview and recent experimental results in southern United States.

PubMed

Abbas, Hamed K; Zablotowicz, Robert M; Weaver, Mark A; Shier, W Thomas; Bruns, H Arnold; Bellaloui, Nacer; Accinelli, Cesare; Abel, Craig A

2013-12-04

Mycotoxin contamination levels in maize kernels are controlled by a complex set of factors including insect pressure, fungal inoculum potential, and environmental conditions that are difficult to predict. Methods are becoming available to control mycotoxin-producing fungi in preharvest crops, including Bt expression, biocontrol, and host plant resistance. Initial reports in the United States and other countries have associated Bt expression with reduced fumonisin, deoxynivalenol, and zearalenone contamination and, to a lesser extent, reduced aflatoxin contamination in harvested maize kernels. However, subsequent field results have been inconsistent, confirming that fumonisin contamination can be reduced by Bt expression, but the effect on aflatoxin is, at present, inconclusive. New maize hybrids have been introduced with increased spectra of insect control and higher levels of Bt expression that may provide important tools for mycotoxin reduction and increased yield due to reduced insect feeding, particularly if used together with biocontrol and host plant resistance.

Simultaneous biogas upgrading and biochemicals production using anaerobic bacterial mixed cultures.

PubMed

Omar, Basma; Abou-Shanab, Reda; El-Gammal, Maie; Fotidis, Ioannis A; Kougias, Panagiotis G; Zhang, Yifeng; Angelidaki, Irini

2018-05-29

A novel biological process to upgrade biogas was developed and optimised during the current study. In this process, CO 2 in the biogas and externally provided H 2 were fermented under mesophilic conditions to volatile fatty acids (VFAs), which are building blocks of higher-value biofuels. Meanwhile, the biogas was upgraded to biomethane (CH 4 >95%), which can be used as a vehicle fuel or injected into the natural gas grid. To establish an efficient fermentative microbial platform, a thermal (at two different temperatures of 70 °C and 90 °C) and a chemical pretreatment method using 2-bromoethanesulfonate were investigated initially to inhibit methanogenesis and enrich the acetogenic bacterial inoculum. Subsequently, the effect of different H 2 :CO 2 ratios on the efficiency of biogas upgrading and production of VFAs were further explored. The composition of the microbial community under different treatment methods and gas ratios has also been unravelled using 16S rRNA analysis. The chemical treatment of the inoculum had successfully blocked the activity of methanogens and enhanced the VFAs production, especially acetate. The chemical treatment led to a significantly better acetate production (291 mg HAc/L) compared to the thermal treatment. Based upon 16S rRNA gene sequencing, it was found that H 2 -utilizing methanogens were the dominant species in the thermally treated inoculum, while a significantly lower abundance of methanogens was observed in the chemically treated inoculum. The highest biogas content (96% (v/v)) and acetate production were achieved for 2H 2 :1CO 2 ratio (v/v), with Acetoanaerobium noterae, as the dominant homoacetogenic hydrogen scavenger. Results from the present study can pave the way towards more development with respect to microorganisms and conditions for high efficient VFAs production and biogas upgrading. Copyright © 2018 Elsevier Ltd. All rights reserved.

Inactivation of Escherichia coli by citral.

PubMed

Somolinos, M; García, D; Condón, S; Mackey, B; Pagán, R

2010-06-01

The aim was to evaluate (i) the resistance of Escherichia coli BJ4 to citral in a buffer system as a function of citral concentration, treatment medium pH, storage time and initial inoculum size, (ii) the role of the sigma factor RpoS on citral resistance of E. coli, (iii) the role of the cell envelope damage in the mechanism of microbial inactivation by citral and (iiii) possible synergistic effects of mild heat treatment and pulsed electric fields (PEF) treatment combined with citral. The initial inoculum size greatly affected the efficacy of citral against E. coli cells. Exposure to 200 microl l(-1) of citral at pH 4.0 for 24 h at 20 degrees C caused the inactivation of more than 5 log(10) cycles of cells starting at an inoculum size of 10(6) or 10(7) CFU ml(-1), whereas increasing the cell concentration to 10(9) CFU ml(-1) caused <1 log(10) cycle of inactivation. Escherichia coli showed higher resistance to citral at pH 4.0 than pH 7.0. The rpoS null mutant strain E. coli BJ4L1 was less resistant to citral than the wild-type strain. Occurrence of sublethal injury to both the cytoplasmic and outer membranes was demonstrated by adding sodium chloride or bile salts to the recovery media. The majority of sublethally injured cells by citral required energy and lipid synthesis for repair. A strongly synergistic lethal effect was shown by mild heat treatment combined with citral but the presence of citral during the application of a PEF treatment did not show any advantage. This work confirms that cell envelope damage is an important event in citral inactivation of bacteria, and it describes the key factors on the inactivation of E. coli cells by citral. Knowledge about the mechanism of microbial inactivation by citral helps establish successful combined preservation treatments.

Environmental parameters affecting inoculum production from lilac leaf pieces infected with Phytophthora ramorum

Treesearch

Nina Shishkoff

2008-01-01

Leaves with lesions caused by Phytophthora ramorum Werres, de Cock & Man in?t Veld often drop off infected plants. Because fallen leaves might serve as sources of inoculum both for the above-ground tissues of host plants and for their roots, this study quantified the inoculum produced by such leaves on the surface of pots when exposed to...

On-farm production of arbuscular mycorrhizal funus inoculum in compost and vermiculite mixtures: results of on-farm demonstrations and impact of compost microbiological quality

USDA-ARS?s Scientific Manuscript database

The sustainability and profitability of many agricultural systems can be enhanced through the utilization of inoculum of arbuscular mycorrhizal fungi. Inocula are commercially available, but inoculum can also be produced on-farm in mixtures of compost and vermiculite with a nurse host plant. Demon...

Hot Water and Copper Coatings in Reused Containers Decrease Inoculum of Fusarium and Cylindrocarpon and Increase Douglas Fir Seedling Growth

Treesearch

R. Kasten Dumroese; Robert L. James; David L. Wenny

2002-01-01

Inoculum of Douglas fir root diseases caused by the fungi Fusarium and Cylindrocarpon is carried from crop to crop in reused containers. Soaking containers for 90 seconds in 80 °C water removed ~99% of Fusarium and 100% of Cylindrocarpon inoculum between growing cycles. Overall seedling growth was also improved:...

Treatment of real wastewater using co-culture of immobilized Chlorella vulgaris and suspended activated sludge.

PubMed

Mujtaba, Ghulam; Lee, Kisay

2017-09-01

The use of algal-bacterial symbiotic association establishes a sustainable and cost-effective strategy in wastewater treatment. Using municipal wastewater, the removal performances of inorganic nutrients (nitrogen and phosphorus) and organic pollutants were investigated by the co-culture system having different inoculum ratios (R) of suspended activated sludge to alginate-immobilized microalgae Chlorella vulgaris. The co-culture reactors with lower R ratios obtained more removal of nitrogen than in pure culture of C. vulgaris. The reactor with R = 0.5 (sludge/microalgae) showed the highest performance representing 66% removal after 24 h and 95% removal after 84 h. Phosphorus was completely eliminated (100%) in the co-culture system with inoculum ratios of 0.5 and 1.0 after 24 h and in the pure C. vulgaris culture after 36 h. The COD level was greatly reduced in the activated sludge reactor, while, it was increasing in pure C. vulgaris culture after 24 h of incubation. However, COD was almost stabilized after 24 h in the reactors with high R ratios such as 2.0, 5.0, and 10 due to the higher concentration of activated sludge. The growth of C. vulgaris was promoted from 0.03 g/L/d to 0.05 g/L/d in the co-culture of low inoculum ratios such as R = 0.5, implying that there exist an optimum inoculum ratio in the co-culture system in order to achieve efficient removal of nutrients. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effects of selected pectinolytic bacterial strains on water-retting of hemp and fibre properties.

PubMed

Di Candilo, M; Bonatti, P M; Guidetti, C; Focher, B; Grippo, C; Tamburini, E; Mastromei, G

2010-01-01

To study the effect of selected bacterial strains on hemp water-retting and properties of retted fibre. The trials were performed in laboratory tanks. The traditional water-retting process, without inoculum addition, was compared to a process modified by inoculating water tanks with two selected pectinolytic bacteria: the anaerobic strain Clostridium sp. L1/6 and the aerobic strain Bacillus sp. ROO40B. Six different incubation times were compared. Half the fibre obtained from each tank was combed. Micromorphological analyses were performed by scanning electron microscopy on uncombed and combed fibres. Moreover, organoleptic and chemical analyses of uncombed fibres were performed. The inoculum, besides speeding up the process, significantly improved the fibre quality. The fibre was not damaged by mechanical hackling, thanks to the good retting level obtained by the addition of selected strains, differently to what happened with the traditionally retted fibre. The best fibre quality was obtained after 3-4 days of retting with the addition of the bacterial inoculum. Retting is the major limitation to an efficient production of high-quality hemp fibres. The water-retting process and fibre quality were substantially improved by simultaneously inoculating water tanks with two selected pectinolytic strains.

Efficiency improvement of an antibody production process by increasing the inoculum density.

PubMed

Hecht, Volker; Duvar, Sevim; Ziehr, Holger; Burg, Josef; Jockwer, Alexander

2014-01-01

Increasing economic pressure is the main driving force to enhance the efficiency of existing processes. We developed a perfusion strategy for a seed train reactor to generate a higher inoculum density for a subsequent fed batch production culture. A higher inoculum density can reduce culture duration without compromising product titers. Hence, a better capacity utilization can be achieved. The perfusion strategy was planned to be implemented in an existing large scale antibody production process. Therefore, facility and process constraints had to be considered. This article describes the initial development steps. Using a proprietary medium and a Chinese hamster ovary cell line expressing an IgG antibody, four different cell retention devices were compared in regard to retention efficiency and reliability. Two devices were selected for further process refinement, a centrifuge and an inclined gravitational settler. A concentrated feed medium was developed to meet facility constraints regarding maximum accumulated perfundate volume. A 2-day batch phase followed by 5 days of perfusion resulted in cell densities of 1.6 × 10(10) cells L(-1) , a 3.5 fold increase compared to batch cultivations. Two reactor volumes of concentrated feed medium were needed to achieve this goal. Eleven cultivations were carried out in bench and 50 L reactors showing acceptable reproducibility and ease of scale up. In addition, it was shown that at least three perfusion phases can be combined within a repeated perfusion strategy. © 2014 American Institute of Chemical Engineers.

Utilization of inoculum of AM fungi produced on-farm for the production of Capsicum annuum: a summary of 7 years of field trials on a conventional vegetable farm

USDA-ARS?s Scientific Manuscript database

Utilization of arbuscular mycorrhizal [AM] fungus inoculum has been encouraged as a way for vegetable farmers to better utilize the AM symbiosis. On-farm systems can economically produce inoculum that has been shown to increase the yield of specific crops. We conducted seven years of field studies...

Fermentation of Ammonia Fiber Expansion Treated and Untreated Barley Straw in a Rumen Simulation Technique Using Rumen Inoculum from Cattle with Slow versus Fast Rate of Fiber Disappearance

PubMed Central

Griffith, Candace L.; Ribeiro, Gabriel O.; Oba, Masahito; McAllister, Tim A.; Beauchemin, Karen A.

2016-01-01

The purpose of this study was to determine the effect of rumen inoculum from heifers with fast vs. slow rate of in situ fiber digestion on the fermentation of complex versus easily digested fiber sources in the forms of untreated and Ammonia Fiber Expansion (AFEX) treated barley straw, respectively, using an artificial rumen simulation technique (Rusitec). In situ fiber digestion was measured in a previous study by incubating untreated barley straw in the rumen of 16 heifers fed a diet consisting of 700 g/kg barley straw and 300 g/kg concentrate. The two heifers with fastest rate of digestion (Fast ≥ 4.18% h-1) and the two heifers with the slowest rate of digestion (Slow ≤ 3.17% h-1) were chosen as inoculum donors for this study. Two Rusitec apparatuses each equipped with eight fermenters were used in a completely randomized block design with two blocks (apparatus) and four treatments in a 2 × 2 factorial arrangement of treatments (Fast or Slow rumen inoculum and untreated or AFEX treated straw). Fast rumen inoculum and AFEX straw both increased (P < 0.05) disappearance of dry matter (DMD), organic matter, true DMD, neutral detergent fiber, acid detergent fiber, and nitrogen (N) with an interactive effect between the two (P < 0.05). Fast rumen inoculum increased (P > 0.05) methane production per gram of digested material for both untreated and AFEX straw, and reduced (interaction, P < 0.05) acetate: propionate ratio for untreated straw. Greater relative populations of Ruminococcus albus (P < 0.05) and increased microbial N production (P = 0.045) were observed in Fast rumen inoculum. AFEX straw in Fast inoculum had greater total bacterial populations than Slow, but for untreated straw this result was reversed (interaction, P = 0.013). These findings indicate that differences in microbial populations in rumen fluid contribute to differences in the capacity of rumen inoculum to digest fiber. PMID:27899919

Characterization of pomegranate juice and whey based novel beverage fermented by kefir grains.

PubMed

Sabokbar, Nayereh; Khodaiyan, Faramarz

2015-06-01

Mixture of pomegranate juice and whey was evaluated as a potential substrate for production of a novel probiotic beverage by kefir grains. Different fermentation conditions were used as viz: two fermentation temperature (19 ºC and 25 ºC) and two levels of kefir grains inoculum (5 % and 8%w/v). pH, acidity, lactose consumption as well as organic acids formation were determined during 32 hours of fermentation. Results showed that kefir grains were able to utilize lactose and decrease pH, increase acidity, produce lactic acid and acetic acid, while the level of citric acid decreased. It was observed these change depended on temperature and level of kefir grains with the highest changes at the temperature of 25 ºC and kefir grains inoculum of 8%w/v. Pomegranate juice and whey mixture therefore may serve as a suitable substrate for the production of novel probiotic dairy-fruit juice beverage by kefir grains and the sensory characteristics of this beverage were shown desirable results.

Utilization of inoculum of AM fungi produced on-farm for the production of Solanum lycopersicum: a summary of 7 years of field trials on a conventional vegetable farm with high soil phosphorus

USDA-ARS?s Scientific Manuscript database

Adding arbuscular mycorrhizal [AM] fungus inoculum to potting media enables vegetable farmers to better take advantage of the AM symbiosis. On-farm production of AM fungus inoculum is a viable alternative to commercially-available inocula. We conducted a seven year experiment at a conventional veg...

Reactions of Grape Rootstocks to Pratylenchus vulnus and Meloidogyne spp.

PubMed

Chitambar, J J; Raski, D J

1984-04-01

Five grape rootstocks were inoculated with 0, 100, 1,000, and 10,000 Pratylenchus vulnus. Dogridge and Saltcreek supported low average total numbers of P. vulnus, 136-705/pot, at 12 months after inoculation. Growth of both rootstocks was not affected. Harmony, Couderc 1613, and Ganzin 1 supported high average total numbers, 6-856 times the inoculum levels. Numbers in Harmony continued to increase at all levels but reduced root weight only at the 10,000 level after 12 months. Numbers in Couderc 1613 decreased by 15-30% after 12 months, and root weight was reduced at the 10,000 level. In Ganzin 1, total nematode numbers diminished after 12 months but were still at high levels; growth reduction was proportional to numbers of nematodes added. Meloidogyne incognita, M. javanica, and M. arenaria produced galls and egg masses in Harmony and Couderc 1613 only at 36 C. Galling in Ganzin 1 increased with increasing temperature. Galls in Ganzin 1 at 18 C supported mature females after 90 days. Harmony was resistant to M. incognita in single and concomitant inoculations of P. vulnus and M. incognita. At 250 days after inoculation, total numbers of P. vulnus increased above the inoculum level and the 150-day values; increase was greatest in P. vulnus added singly. Neither nematode species affected growth of Harmony.

Sheared-root inocula of vesicular-arbuscular mycorrhizal fungi.

PubMed

Sylvia, D M; Jarstfer, A G

1992-01-01

For efficient handling, vesicular-arbuscular mycorrhizal fungi should be processed into small and uniform inocula; however, processing can reduce the inoculum density. In this article we describe the preparation and use of sheared-root inocula of Glomus spp. in which inoculum densities were increased during processing. Our objectives were to determine inoculum viability and density after shearing and to ascertain if the sheared inocula could be pelletized or used with a gel carrier. Root samples were harvested from aeroponic cultures, blotted dry, cut into 1-cm lengths, and sheared in a food processor for up to 80 s. After shearing, the inoculum was washed over sieves, and the propagule density in each fraction was determined. Sheared inocula were also encapsulated in carrageenan or used in a gel carrier. Shearing aeroponically produced root inocula reduced particle size. Propagule density increased with decreasing size fraction down to a size of 63 mum, after which propagule density decreased. The weighted-average propagule density of the inoculum was 135,380 propagules g (dry weight) of sheared root material. Sheared roots were encapsulated successfully in carrageenan, and the gel served as an effective carrier. Aeroponic root inoculum was stored dry at 4 degrees C for 23 months without significant reduction in propagule density; however, this material was not appropriate for shearing. Moist roots, useful for shearing, began to lose propagule density after 1 month of storage. Shearing proved to be an excellent method to prepare viable root inocula of small and uniform size, allowing for more efficient and effective use of limited inoculum supplies.

Biohydrogen production from lactose: influence of substrate and nitrogen concentration.

PubMed

Moreno, R; Fierro, J; Fernández, C; Cuetos, M J; Gómez, X

2015-01-01

Hydrogen produced from renewable sources may be considered the energy vector of the future. However, reducing process costs is imperative in order to achieve this goal. In the present research, the effect of nitrogen (N), initial pH and substrate content for starting up the dark fermentative process was studied using the response surface methodology. Anaerobic digested dried sludge (biosolid pellets) was used as the inoculum. Synthetic wastewater was used as the substrate in batch reactors. A decrease in H2 production was observed with the increase in N and lactose concentrations. This drop was considerably greater when the concentration of lactose was at its lower level. Although the increase in lactose concentration results in a lower H2 production, the effect of N on the response is attenuated at higher levels of lactose. On the other hand, the effect of initial pH on the fermentation system was not significant. The evaluation on the process under semi-continuous conditions was performed using anaerobic sequencing batch reactors (ASBRs). The process was evaluated at different C/N ratios using synthetic wastewater. Results showed higher hydrogen yields with the gradual decrease in nitrogen content. The addition of cheese whey to the ASBR resulted in a H2 production rate of 0.18 L H2 L(-1) d(-1).

Development of an In Vivo and In Vitro Ileal Fermentation Method in a Growing Pig Model.

PubMed

Montoya, Carlos A; de Haas, Edward S; Moughan, Paul J

2018-02-01

Substantial microbial fermentation may occur mainly in the lower small intestine (SI) of human adults, but there is no established methodology to determine this. The study aimed to develop a combined in vivo and in vitro methodology for ileal fermentation based on the pig as an animal model for digestion in human adults. Several aspects of a combined in vivo/in vitro ileal fermentation assay were evaluated. Male 9-wk-old pigs (n = 30; mean ± SD body weight: 23 ± 1.6 kg) were fed a human-type diet (143, 508, 45, 49, and 116 g/kg dry matter diet of crude protein, starch, total lipid, ash, and total dietary fiber) for 15 d. On day 15, pigs were killed, and the last third of the SI was collected to prepare an ileal digesta-based inoculum. Terminal jejunal digesta (last 50 cm of the second third of the SI) were collected as substrate for the assay to test the form of substrate (fresh or freeze-dried), origin (location in jejunum or SI) of the substrate, storage of the inoculum, incubation time (1.2-6.8 h), pH of the medium, and inoculum concentration (6-26 mg inoculum/100 mg substrate). The group of donor pigs used to prepare the inoculum, form of the substrate, origin of the substrate, origin of the inoculum (location in the SI), storage of the inoculum, incubation time, and inoculum concentration did not influence the in vitro ileal organic matter (OM) fermentability (P > 0.05). The in vitro ileal OM fermentability decreased when the pH of the medium increased from 5.5 to 7.5 (31% to 28%; P ≤ 0.05). Predicted (in vivo/in vitro) apparent ileal OM digestibility was similar to the value measured in vivo. Thirty-percent of the terminal jejunal digesta OM was fermented in the ileum. Fiber fermentation in the ileum can be studied using the optimized in vivo/in vitro ileal fermentation method.

Valorization of indigenous dairy cattle breed through salami production.

PubMed

Gaglio, Raimondo; Francesca, Nicola; Maniaci, Giuseppe; Corona, Onofrio; Alfonzo, Antonio; Giosuè, Cristina; Di Noto, Annamaria; Cardamone, Cinzia; Sardina, Maria Teresa; Portolano, Baldassare; Alabiso, Marco

2016-04-01

The aim of the research was to produce salami manufactured with meat of three different commercial categories of bovine breed: cow on retirement, beef and young bull. A total of six experimental productions, at small-scale plant, were carried out with and without starter culture inoculums. The evolution of physico-chemical parameters in all trials followed the trend already registered for other fermented meat products. Several LAB species were found during process with different levels of species diversity and frequency of isolation among inoculated (mainly Pediococcus pentosaceus and Staphylococcus xylosus) and uninoculated (mainly Enterococcus devriesei, Lactobacillus curvatus and Lactobacillus sakei) trials. Enterobacteriaceae were found at very low levels during the entire ripening period and no pathogenic bacteria were found in any samples. The multivariate analysis showed that starter inoculums and meat affected significantly the physico-chemical and the microbiological composition of salami. The sensory analysis evidenced the highest overall acceptability was displayed by salami produced with meat from cow on retirement. Copyright © 2015 Elsevier Ltd. All rights reserved.

Antimicrobial Activity of Aroma Compounds against Saccharomyces cerevisiae and Improvement of Microbiological Stability of Soft Drinks as Assessed by Logistic Regression▿

PubMed Central

Belletti, Nicoletta; Kamdem, Sylvain Sado; Patrignani, Francesca; Lanciotti, Rosalba; Covelli, Alessandro; Gardini, Fausto

2007-01-01

The combined effects of a mild heat treatment (55°C) and the presence of three aroma compounds [citron essential oil, citral, and (E)-2-hexenal] on the spoilage of noncarbonated beverages inoculated with different amounts of a Saccharomyces cerevisiae strain were evaluated. The results, expressed as growth/no growth, were elaborated using a logistic regression in order to assess the probability of beverage spoilage as a function of thermal treatment length, concentration of flavoring agents, and yeast inoculum. The logit models obtained for the three substances were extremely precise. The thermal treatment alone, even if prolonged for 20 min, was not able to prevent yeast growth. However, the presence of increasing concentrations of aroma compounds improved the stability of the products. The inhibiting effect of the compounds was enhanced by a prolonged thermal treatment. In fact, it influenced the vapor pressure of the molecules, which can easily interact within microbial membranes when they are in gaseous form. (E)-2-Hexenal showed a threshold level, related to initial inoculum and thermal treatment length, over which yeast growth was rapidly inhibited. Concentrations over 100 ppm of citral and thermal treatment longer than 16 min allowed a 90% probability of stability for bottles inoculated with 105 CFU/bottle. Citron gave the most interesting responses: beverages with 500 ppm of essential oil needed only 3 min of treatment to prevent yeast growth. In this framework, the logistic regression proved to be an important tool to study alternative hurdle strategies for the stabilization of noncarbonated beverages. PMID:17616627

Wastewater Utilization for Poly-β-Hydroxybutyrate Production by the Cyanobacterium Aulosira fertilissima in a Recirculatory Aquaculture System▿

PubMed Central

Samantaray, Shilalipi; Nayak, Jitendra Kumar; Mallick, Nirupama

2011-01-01

Intensive aquaculture releases large quantities of nutrients into aquatic bodies, which can lead to eutrophication. The objective of this study was the development of a biological recirculatory wastewater treatment system with a diazotrophic cyanobacterium, Aulosira fertilissima, and simultaneous production of valuable product in the form of poly-β-hydroxybutyrate (PHB). To investigate this possible synergy, batch scale tests were conducted under a recirculatory aquaculture system in fiber-reinforced plastic tanks enhanced by several manageable parameters (e.g., sedimentation, inoculum size, depth, turbulence, and light intensity), an adequate combination of which showed better productivity. The dissolved-oxygen level increased in the range of 3.2 to 6.9 mg liter−1 during the culture period. Nutrients such as ammonia, nitrite, and phosphate decreased to as low as zero within 15 days of incubation, indicating the system's bioremediation capability while yielding valuable cyanobacterial biomass for PHB production. Maximum PHB accumulation in A. fertilissima was found in sedimented fish pond discharge at 20-cm culture depth with stirring and an initial inoculum size of 80 mg dry cell weight (dcw) liter−1. Under optimized conditions, the PHB yield was boosted to 92, 89, and 80 g m−2, respectively for the summer, rainy, and winter seasons. Extrapolation of the result showed that a hectare of A. fertilissima cultivation in fish pond discharge would give an annual harvest of ∼17 tons dry biomass, consisting of 14 tons of PHB with material properties comparable to those of the bacterial polymer, with simultaneous treatment of 32,640 m3 water discharge. PMID:21984242

Wastewater utilization for poly-β-hydroxybutyrate production by the cyanobacterium Aulosira fertilissima in a recirculatory aquaculture system.

PubMed

Samantaray, Shilalipi; Nayak, Jitendra Kumar; Mallick, Nirupama

2011-12-01

Intensive aquaculture releases large quantities of nutrients into aquatic bodies, which can lead to eutrophication. The objective of this study was the development of a biological recirculatory wastewater treatment system with a diazotrophic cyanobacterium, Aulosira fertilissima, and simultaneous production of valuable product in the form of poly-β-hydroxybutyrate (PHB). To investigate this possible synergy, batch scale tests were conducted under a recirculatory aquaculture system in fiber-reinforced plastic tanks enhanced by several manageable parameters (e.g., sedimentation, inoculum size, depth, turbulence, and light intensity), an adequate combination of which showed better productivity. The dissolved-oxygen level increased in the range of 3.2 to 6.9 mg liter⁻¹ during the culture period. Nutrients such as ammonia, nitrite, and phosphate decreased to as low as zero within 15 days of incubation, indicating the system's bioremediation capability while yielding valuable cyanobacterial biomass for PHB production. Maximum PHB accumulation in A. fertilissima was found in sedimented fish pond discharge at 20-cm culture depth with stirring and an initial inoculum size of 80 mg dry cell weight (dcw) liter⁻¹. Under optimized conditions, the PHB yield was boosted to 92, 89, and 80 g m⁻², respectively for the summer, rainy, and winter seasons. Extrapolation of the result showed that a hectare of A. fertilissima cultivation in fish pond discharge would give an annual harvest of ∼17 tons dry biomass, consisting of 14 tons of PHB with material properties comparable to those of the bacterial polymer, with simultaneous treatment of 32,640 m³ water discharge.

Characterization of anode and anolyte community growth and the impact of impedance in a microbial fuel cell.

PubMed

Sanchez-Herrera, Diana; Pacheco-Catalan, Daniella; Valdez-Ojeda, Ruby; Canto-Canche, Blondy; Dominguez-Benetton, Xochitl; Domínguez-Maldonado, Jorge; Alzate-Gaviria, Liliana

2014-12-09

A laboratory-scale two-chamber microbial fuel cell employing an aerated cathode with no catalyst was inoculated with mixed inoculum and acetate as the carbon source. Electrochemical impedance spectroscopy (EIS) was used to study the behavior of the MFC during initial biofilm (week 1) and maximum power density (week 20). EIS were performed on the anode chamber, biofilm (without anolyte) and anolyte (without biofilm). Nyquist plots of the EIS data were fitted with two equivalent electrical circuits to estimate the contributions of intrinsic resistances to the overall internal MFC impedance at weeks 1 and 20, respectively. The results showed that the system tended to increase power density from 15 ± 3 (week 1) to 100 ± 15 mW/m(2) (week 20) and current density 211 ± 7 (week 1) to 347 ± 29 mA/m(2) (week 20). The Samples were identified by pyrosequencing of the 16S rRNA gene and showed that initial inoculum (week 1) was constituted by Proteobacteria (40%), Bacteroidetes (22%) and Firmicutes (18%). At week 20, Proteobacterial species were predominant (60%) for electricity generation in the anode biofilm, being 51% Rhodopseudomonas palustris. Meanwhile on anolyte, Firmicutes phylum was predominant with Bacillus sp. This study proved that under the experimental conditions used there is an important contribution from the interaction of the biofilm and the anolyte on cell performance. Table 1 presents a summary of the specific influence of each element of the system under study. The results showed certain members of the bacterial electrode community increased in relative abundance from the initial inoculum. For example, Proteobacterial species are important for electricity generation in the anode biofilms and Firmicutes phylum was predominant on anolyte to transfer electron. R1 is the same in the three systems and no variation is observed over time. The biofilm makes a significant contribution to the charge transfer processes at the electrode (R2 and Cdl) and, consequently, on the performance of the anode chamber. The biofilm can act as a barrier which reduces diffusion of the anolyte towards the electrode, all the while behaving like a porous material. The anolyte and its interaction with the biofilm exert a considerable influence on diffusion processes, given that it presents the highest values for Rd which increased at week 20.

Crop Rotation and Races of Meloidogyne incognita in Cotton Root-knot Management

PubMed Central

Kirkpatrick, T. L.; Sasser, J. N.

1984-01-01

The influence o f various crop rotations and nematode inoculum levels on subsequent population densities of Meloidogyne incognita races 1 and 3 were studied in microplots. Ten different 3-year sequences o f cotton, corn, peanut, or soybean, all with cotton as the 3rd-year crop, were grown in microplots infested with each race. Cotton monoculture, two seasons o f corn, or cotton followed by corn resulted in high race 3 population densities and severe root galling on cotton the 3rd year. Peanut for 2 years preceding cotton most effectively decreased the race 3 population and root galls on cotton the 3rd year. Race 1 did not significantly influence cotton growth or yield at initial populations of up to 5,000 eggs/500 cm³ soil. At 5,000 eggs/500 cm³, cotton growth was suppressed by race 3 but yield was not affected. PMID:19294030

Optimization of culture conditions and bench-scale production of L-asparaginase by submerged fermentation of Aspergillus terreus MTCC 1782.

PubMed

Gurunathan, Baskar; Sahadevan, Renganathan

2012-07-01

Optimization of culture conditions for L-asparaginase production by submerged fermentation of Aspergillus terreus MTCC 1782 was studied using a 3-level central composite design of response surface methodology and artificial neural network linked genetic algorithm. The artificial neural network linked genetic algorithm was found to be more efficient than response surface methodology. The experimental L-asparaginase activity of 43.29 IU/ml was obtained at the optimum culture conditions of temperature 35 degrees C, initial pH 6.3, inoculum size 1% (v/v), agitation rate 140 rpm, and incubation time 58.5 h of the artificial neural network linked genetic algorithm, which was close to the predicted activity of 44.38 IU/ml. Characteristics of L-asparaginase production by A. terreus MTCC 1782 were studied in a 3 L bench-scale bioreactor.

Sublethal effects of iridovirus disease in a mosquito.

PubMed

Marina, Carlos F; Arredondo-Jiménez, Juan I; Castillo, Alfredo; Williams, Trevor

1999-05-01

Recognition of the importance of debilitating effects of insect virus diseases is currently growing. Commonly observed effects of sublethal infection at the individual level include extended development times, reduced pupal and adult weights, and lowered fecundity. However, for the most part, sublethal infections are assumed to be present in survivors of an inoculum challenge, rather than demonstrated to be present by microscopy or molecular techniques. Invertebrate iridescent viruses are dsDNA viruses capable of causing disease with symptoms obvious to the naked eye, a "patent" infection, that is lethal. Furthermore, inapparent "covert" infections may occur that are non-lethal and which can only be detected using bioassay or molecular techniques. In this study, replication of Invertebrate iridescent virus 6 in Aedes aegypti larvae was demonstrated in the absence of patent disease. A sensitive insect bioassay (using Galleria mellonella) allowed the detection of covert infections, which were more common than patent infections. A concentration-response relationship was detected for the incidence of patent infections. Covert infections were up to 2 orders of magnitude commoner than patent infections, but the prevalence of covert infections did not appear to be related to virus inoculum concentration. Exposure of larvae to virus inoculum resulted in extended juvenile development times. A reduction in the mean and an increase in the variability of fecundity and adult progeny production was observed in females exposed to an inoculum challenge, although formal analysis was not possible. Males appeared capable of passing virus to uninfected females during the mating process. Covertly infected females were smaller and had shorter lifespans than control or virus-challenged females. A conservative estimate for the reduction in the net reproductive rate (R 0 ) of such insects was calculated at slightly more than 20% relative to controls.

Acetate accumulation enhances mixed culture fermentation of biomass to lactic acid.

PubMed

Khor, Way Cern; Roume, Hugo; Coma, Marta; Vervaeren, Han; Rabaey, Korneel

2016-10-01

Lactic acid is a high-in-demand chemical, which can be produced through fermentation of lignocellulosic feedstock. However, fermentation of complex substrate produces a mixture of products at efficiencies too low to justify a production process. We hypothesized that the background acetic acid concentration plays a critical role in lactic acid yield; therefore, its retention via selective extraction of lactic acid or its addition would improve overall lactic acid production and eliminate net production of acetic acid. To test this hypothesis, we added 10 g/L of acetate to fermentation broth to investigate its effect on products composition and concentration and bacterial community evolution using several substrate-inoculum combinations. With rumen fluid inoculum, lactate concentrations increased by 80 ± 12 % (cornstarch, p < 0.05) and 16.7 ± 0.4 % (extruded grass, p < 0.05) while with pure culture inoculum (Lactobacillus delbrueckii and genetically modified (GM) Escherichia coli), a 4 to 23 % increase was observed. Using rumen fluid inoculum, the bacterial community was enriched within 8 days to >69 % lactic acid bacteria (LAB), predominantly Lactobacillaceae. Higher acetate concentration promoted a more diverse LAB population, especially on non-inoculated bottles. In subsequent tests, acetate was added in a semi-continuous percolation system with grass as substrate. These tests confirmed our findings producing lactate at concentrations 26 ± 5 % (p < 0.05) higher than the control reactor over 20 days operation. Overall, our work shows that recirculating acetate has the potential to boost lactic acid production from waste biomass to levels more attractive for application.

Clinically Relevant Plasma Concentrations of Colistin in Combination with Imipenem Enhance Pharmacodynamic Activity against Multidrug-Resistant Pseudomonas aeruginosa at Multiple Inocula▿†

PubMed Central

Bergen, Phillip J.; Forrest, Alan; Bulitta, Jürgen B.; Tsuji, Brian T.; Sidjabat, Hanna E.; Paterson, David L.; Li, Jian; Nation, Roger L.

2011-01-01

The use of combination antibiotic therapy may be beneficial against rapidly emerging resistance in Pseudomonas aeruginosa. The aim of this study was to systematically investigate in vitro bacterial killing and resistance emergence with colistin alone and in combination with imipenem against multidrug-resistant (MDR) P. aeruginosa. Time-kill studies were conducted over 48 h using 5 clinical isolates and ATCC 27853 at two inocula (∼106 and ∼108 CFU/ml); MDR, non-MDR, and colistin-heteroresistant and -resistant strains were included. Nine colistin-imipenem combinations were investigated. Microbiological response was examined by log changes at 6, 24, and 48 h. Colistin combined with imipenem at clinically relevant concentrations increased the levels of killing of MDR and colistin-heteroresistant isolates at both inocula. Substantial improvements in activity with combinations were observed across 48 h with all colistin concentrations at the low inoculum and with colistin at 4× and 16× MIC (or 4 and 32 mg/liter) at the high inoculum. Combinations were additive or synergistic against imipenem-resistant isolates (MICs, 16 and 32 mg/liter) at the 106-CFU inoculum in 9, 11, and 12 of 18 cases (i.e., 9 combinations across 2 isolates) at 6, 24, and 48 h, respectively, and against the same isolates at the 108-CFU inoculum in 11, 7, and 8 cases, respectively. Against a colistin-resistant strain (MIC, 128 mg/liter), combinations were additive or synergistic in 9 and 8 of 9 cases at 24 h at the 106- and 108-CFU inocula, respectively, and in 5 and 7 cases at 48 h. This systematic study provides important information for optimization of colistin-imipenem combinations targeting both colistin-susceptible and colistin-resistant subpopulations. PMID:21876058

Canola Cake as a Potential Substrate for Proteolytic Enzymes Production by a Selected Strain of Aspergillus oryzae: Selection of Process Conditions and Product Characterization

PubMed Central

Freitas, Adriana C.; Castro, Ruann J. S.; Fontenele, Maria A.; Egito, Antonio S.; Farinas, Cristiane S.; Pinto, Gustavo A. S.

2013-01-01

Oil cakes have excellent nutritional value and offer considerable potential for use in biotechnological processes that employ solid-state fermentation (SSF) for the production of high value products. This work evaluates the feasibility of using canola cake as a substrate for protease production by a selected strain of Aspergillus oryzae cultivated under SSF. The influences of the following process parameters were considered: initial substrate moisture content, incubation temperature, inoculum size, and pH of the buffer used for protease extraction and activity analysis. Maximum protease activity was obtained after cultivating Aspergillus oryzae CCBP 001 at 20°C, using an inoculum size of 107 spores/g in canola cake medium moistened with 40 mL of water to 100 g of cake. Cultivation and extraction under selected conditions increased protease activity 5.8-fold, compared to the initial conditions. Zymogram analysis of the enzymatic extract showed that the protease molecular weights varied between 31 and 200 kDa. The concentrated protease extract induced clotting of casein in 5 min. The results demonstrate the potential application of canola cake for protease production under SSF and contribute to the technological advances needed to increase the efficiency of processes designed to add value to agroindustrial wastes. PMID:24455400

Effect of cultural conditions on antrodin C production by basidiomycete Antrodia camphorata in solid-state fermentation.

PubMed

Xia, Yongjun; Wang, Yuanlong; Zhang, Bobo; Xu, Ganrong; Ai, Lianzhong

2014-01-01

Antrodia camphorata is a medicinal fungus and antrodin C is one of the main bioactive components of A. camphorata in the submerged fermentation (SmF). To optimize the culture conditions, the factors influencing the production of antrodin C by A. camphorata under solid-state fermentation (SSF) were investigated in this study. Different solid substrates and external nitrogen sources were tested for their efficiency in producing antrodin C. The response surface methodology was applied to evaluate the influence of several variables, namely, the concentrations of soybean meal, initial moisture content, and inoculum density on antrodin C production in solid-state fermentation. The experimental results show that the optimum fermentation medium for antrodin C production by A. camphorata was composed of 0.578 g soybean meal, 0.05 g Na2 HPO4 , 0.05 g MgSO4 for 100 g rice, with 51.83% initial moisture content, 22 day culture time, 28 °C culture temperature, and 35.54% inoculum density. At optimized conditions, 6,617.36 ± 92.71 mg kg(-1) yield of antrodin C was achieved. Solid-state fermentation is one good cultural method to improve the production of antrodin C by A. camphorata. © 2014 International Union of Biochemistry and Molecular Biology, Inc.

Application of a mixed culture of adapted acidophilic bacteria in two-step bioleaching of spent lithium-ion laptop batteries

NASA Astrophysics Data System (ADS)

Heydarian, Ahmad; Mousavi, Seyyed Mohammad; Vakilchap, Farzane; Baniasadi, Mahsa

2018-02-01

The rapid increase in the production of electrical and electronic equipment, along with higher consumption of these products, has caused defective and obsolete equipment to accumulate in the environment. In this research, bioleaching of spent lithium-ion batteries (LIBs) used in laptops is carried out under two-step condition based on the bacterial activities of a mixture of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans. First, the best inoculum ratio of two acidophilic bacteria for the mixed culture is obtained. Next, adaptation is carried out successfully and the solid-to-liquid ratio reaches 40 g L-1. Response surface methodology is utilized to optimize the effective variables of initial pH, iron sulfate and sulfur concentrations. The maximum recovery of metal is about 99.2% for Li, 50.4% for Co and 89.4% for Ni under optimum conditions of 36.7 g L-1 iron sulfate concentration, 5.0 g L-1 sulfur concentration and initial pH of 1.5 for the best inoculum ratio of 3/2. Results of FE-SEM, XRD and FTIR analysis before and after bioleaching confirm that bacterial activity is a promising and effective route for metal recovery from spent LIBs. Toxicity assessment tests demonstrate the suitability of the bioleached residual as a nonhazardous material that meets environmental limitations for safe disposal.

Antimicrobial Effects of β-Lactams on Imipenem-Resistant Ceftazidime-Susceptible Pseudomonas aeruginosa

PubMed Central

Wi, Yu Mi; Choi, Ji-Young; Lee, Ji-Young; Kang, Cheol-In; Chung, Doo Ryeon; Peck, Kyong Ran; Song, Jae-Hoon

2017-01-01

ABSTRACT We studied the resistance mechanism and antimicrobial effects of β-lactams on imipenem-resistant Pseudomonas aeruginosa isolates that were susceptible to ceftazidime as detected by time-kill curve methods. Among 215 P. aeruginosa isolates from hospitalized patients in eight hospitals in the Republic of Korea, 18 isolates (23.4% of 77 imipenem-resistant isolates) were imipenem resistant and ceftazidime susceptible. Multilocus sequence typing revealed diverse genotypes, which indicated independent emergence. These 18 isolates were negative for carbapenemase genes. All 18 imipenem-resistant ceftazidime-susceptible isolates showed decreased mRNA expression of oprD, and overexpression of mexB was observed in 13 isolates. In contrast, overexpression of ampC, mexD, mexF, or mexY was rarely found. Time-kill curve methods were applied to three selected imipenem-resistant ceftazidime-susceptible isolates at a standard inoculum (5 × 105 CFU/ml) or at a high inoculum (5 × 107 CFU/ml) to evaluate the antimicrobial effects of β-lactams. Inoculum effects were detected for all three β-lactam antibiotics, ceftazidime, cefepime, and piperacillin-tazobactam, against all three isolates. The antibiotics had significant killing effects in the standard inoculum, but no effects in the high inoculum were observed. Our results suggest that β-lactam antibiotics should be used with caution in patients with imipenem-resistant ceftazidime-susceptible P. aeruginosa infection, especially in high-inoculum infections such as endocarditis and osteomyelitis. PMID:28373200

Influence of carbon source and inoculum type on anaerobic biomass adhesion on polyurethane foam in reactors fed with acid mine drainage.

PubMed

Rodriguez, Renata P; Zaiat, Marcelo

2011-04-01

This paper analyzes the influence of carbon source and inoculum origin on the dynamics of biomass adhesion to an inert support in anaerobic reactors fed with acid mine drainage. Formic acid, lactic acid and ethanol were used as carbon sources. Two different inocula were evaluated: one taken from an UASB reactor and other from the sediment of a uranium mine. The values of average colonization rates and the maximum biomass concentration (C(max)) were inversely proportional to the number of carbon atoms in each substrate. The highest C(max) value (0.35 g TVS g(-1) foam) was observed with formic acid and anaerobic sludge as inoculum. Maximum colonization rates (v(max)) were strongly influenced by the type of inoculum when ethanol and lactic acid were used. For both carbon sources, the use of mine sediment as inoculum resulted in a v(max) of 0.013 g TVS g(-1) foam day(-1), whereas 0.024 g TVS g(-1) foam day(-1) was achieved with anaerobic sludge. Copyright © 2011 Elsevier Ltd. All rights reserved.

Optimization of the production of mycorrhizal inoculum on substrate with organic fertilizer

PubMed Central

Coelho, Ieda R; Pedone-Bonfim, Maria VL; Silva, Fábio SB; Maia, Leonor C

2014-01-01

The system for production of inoculum of arbuscular mycorrhizal fungi (AMF) using sand and vermiculite irrigated with nutrient solution is promising. However, organic amendments added to the substrate can stimulate sporulation of AMF and replace the nutrient solution. The aim of this study was to maximize the production of AMF (Acaulospora longula, Claroideoglomus etunicatum, Dentiscutata heterogama and Gigaspora albida) using selected organic substrates (vermicompost, coir dust and Tropstrato) together with sand and vermiculite. The production of spores varied among the tested AMF and according to the organic source added to the substrate. The vermicompost promoted higher sporulation of A. longula in relation to the other AMF and substrates. The Tropstrato® inhibited the sporulation of D. heterogama while the reproduction of C. etunicatum was not affected by the organic compounds. The inoculum of A. longula also showed a high number of infective propagules and promoted biomass accumulation in maize plants. The system of inoculum production using sand and vermiculite + 10% vermicompost favors the production of infective inoculum of A. longula with the fungus benefiting growth of corn plants. PMID:25763020

Fermentative hydrogen gas production using biosolids pellets as the inoculum source.

PubMed

Kalogo, Youssouf; Bagley, David M

2008-02-01

Biosolids pellets produced from anaerobically digested municipal wastewater sludge by drying to greater than 90% total solids at 110-115 degrees C for at least 75 min, were tested for their suitability as an inoculum source for fermentative hydrogen production. The hydrogen recoveries (mg gaseous H(2) produced as COD/mg added substrate COD) for glucose-fed batch systems were equal, 20.2-21.5%, between biosolids pellets and boiled anaerobic digester sludge as inoculum sources. Hydrogen recoveries from primary sludge were 2.4% and 3.5% using biosolids pellets and boiled sludge, respectively, and only 0.2% and 0.8% for municipal wastewater. Biosolids pellets should be a practical inoculum source for fermentative hydrogen reactors, although the effectiveness will depend on the wastewater treated.

Relationships between transit time in man and in vitro fermentation of dietary fiber by fecal bacteria.

PubMed

Oufir, L E; Barry, J L; Flourié, B; Cherbut, C; Cloarec, D; Bornet, F; Galmiche, J P

2000-08-01

To assess the effects of drug-induced changes in mean transit time (MTT) on the activity of human fecal flora in vitro. The activity of fecal flora was estimated by the ability of a fecal inoculum to ferment a substrate (beet fiber) in vitro in a batch system for 24 h. The inoculum was collected from 8 healthy volunteers studied during three 3-week randomized periods, who received a controlled diet alone (control period) or the same diet with either cisapride or loperamide. Cisapride and loperamide were adjusted in order to halve and double MTT measured during the control period. At the end of each period, the percentage disappearance of the initial added substrate and the concentration and the profile of short-chain fatty acids (SCFAs), were determined. In the control period, the pH of the inoculum and SCFA concentration were inversely related to MTT (P=0.0001). Individual SCFA production was also significantly related to MTT (P<0.01). Cisapride-reduced transit time was associated with a significant rise in the concentrations of total SCFAs (P<0.05), propionic and butyric acids (P<0.05) and the percentage substrate disappearance (P<0.05). Inverse relations were observed during the loperamide period. Moreover, MTT was inversely related to the percentage substrate disappearance (P<0.001), SCFA production (P<0.001) and butyrate production (P<0.0005). Changes in MTT alter bacterial activity and modify the bacterial pathways affecting the proportion of individual SCFAs. European Journal of Clinical Nutrition (2000) 54, 603-609

Quantitative analysis of the growth of Salmonella stanley during alfalfa sprouting and evaluation of Enterobacter aerogenes as its surrogate.

PubMed

Liu, Bin; Schaffner, Donald W

2007-02-01

Raw seed sprouts have been implicated in several food poisoning outbreaks in the last 10 years. Few studies have included investigations of factors influencing the effectiveness of testing spent irrigation water, and in no studies to date has a nonpathogenic surrogate been identified as suitable for large-scale irrigation water testing trials. Alfalfa seeds were inoculated with Salmonella Stanley or its presumptive surrogate (nalidixic acid-resistant Enterobacter aerogenes) at three concentrations (-3, -30, and -300 CFU/g) and were then transferred into either flasks or a bench top-scale sprouting chamber. Microbial concentrations were determined in seeds, sprouts, and irrigation water at various times during a 4-day sprouting process. Data were fit to logistic regression models, and growth rates and maximum concentrations were compared using the generalized linear model procedure of SAS. No significant differences in growth rates were observed among samples taken from flasks or the chamber. Microbial concentrations in irrigation water were not significantly different from concentrations in sprout samples obtaihed at the same time. E. aerogenes concentrations were similar to those of Salmonella Stanley at corresponding time points for all three inoculum concentrations. Growth rates were also constant regardless of inoculum concentration or strain, except that lower inoculum concentrations resulted in lower final concentrations proportional to their initial concentrations. This research demonstrated that a nonpathogenic easy-to-isolate surrogate (nalidixic acid-resistant E. aerogenes) provides results similar to those obtained with Salmonella Stanley, supporting the use of this surrogate in future large-scale experiments.

Changes in ectomycorrhizal fungal community composition and declining diversity along a 2-million-year soil chronosequence.

PubMed

Albornoz, Felipe E; Teste, François P; Lambers, Hans; Bunce, Michael; Murray, Dáithí C; White, Nicole E; Laliberté, Etienne

2016-10-01

Ectomycorrhizal (ECM) fungal communities covary with host plant communities along soil fertility gradients, yet it is unclear whether this reflects changes in host composition, fungal edaphic specialization or priority effects during fungal community establishment. We grew two co-occurring ECM plant species (to control for host identity) in soils collected along a 2-million-year chronosequence representing a strong soil fertility gradient and used soil manipulations to disentangle the effects of edaphic properties from those due to fungal inoculum. Ectomycorrhizal fungal community composition changed and richness declined with increasing soil age; these changes were linked to pedogenesis-driven shifts in edaphic properties, particularly pH and resin-exchangeable and organic phosphorus. However, when differences in inoculum potential or soil abiotic properties among soil ages were removed while host identity was held constant, differences in ECM fungal communities and richness among chronosequence stages disappeared. Our results show that ECM fungal communities strongly vary during long-term ecosystem development, even within the same hosts. However, these changes could not be attributed to short-term fungal edaphic specialization or differences in fungal inoculum (i.e. density and composition) alone. Rather, they must reflect longer-term ecosystem-level feedback between soil, vegetation and ECM fungi during pedogenesis. © 2016 John Wiley & Sons Ltd.

Interaction of Trichoderma asperellum with Phytophthora ramorum inoculum soil populations and enzyme secretion

Treesearch

Supriya Sharma; Wolfgang Schweigkofler; Karen Suslow; Timothy L. Widmer

2017-01-01

There is a continuing desire to investigate the potential of biological control to manage the spread of Phytophthora ramorum. A specific isolate of Trichoderma asperellum has been demonstrated to be effective in reducing P. ramorum soil populations to non-detectable levels. This study was conducted...

Rationale behind high-dose amoxicillin therapy for acute otitis media due to penicillin-nonsusceptible pneumococci: support from in vitro pharmacodynamic studies.

PubMed Central

Lister, P D; Pong, A; Chartrand, S A; Sanders, C C

1997-01-01

To evaluate whether increased doses of amoxicillin should be used to treat acute pneumococcal otitis media, an in vitro pharmacokinetic model was used to evaluate the killing of pneumococci by amoxicillin when middle ear pharmacokinetics were simulated. Logarithmic-phase cultures were exposed to peak concentrations of 3, 6, and 9 microg of amoxicillin per ml every 12 h, and an elimination half-life of 1.6 h was simulated. Changes in viable bacterial counts were measured over 36 h. All three doses rapidly decreased the viable bacterial counts of penicillin-susceptible strains below the 10-CFU/ml limit of detection by 6 to 10 h and maintained counts below this limit through 36 h. The 3-microg/ml peak dose was much less effective against two of three strains with intermediate penicillin resistance and all three penicillin-resistant strains, with bacterial counts approaching those in drug-free control cultures by 12 h. The 6-microg/ml peak dose completely eliminated two of three strains with intermediate penicillin resistance and maintained viable counts of the other nonsusceptible strains at 1.5 to 2 logs below the initial inoculum through 36 h. The 9-microg/ml peak dose was most effective, completely eliminating all three strains with intermediate penicillin resistance and maintaining the viable counts of the resistant strains at 3 to 4 logs below the original inoculum. The pharmacodynamics observed in this study suggest that peak concentrations of amoxicillin of 6 to 9 microg/ml may be sufficient for the elimination of penicillin-nonsusceptible pneumococcal strains causing otitis media, especially those with intermediate resistance to amoxicillin. In vivo pharmacokinetic studies are needed to determine if these levels can be achieved in middle ear fluid with amoxicillin at 70 to 90 mg/kg/day divided into two daily doses. If these levels are reliably achieved, then clinical studies are warranted. PMID:9303386

Effects of simulated Mars conditions on the survival and growth of Escherichia coli and Serratia liquefaciens.

PubMed

Berry, Bonnie J; Jenkins, David G; Schuerger, Andrew C

2010-04-01

Escherichia coli and Serratia liquefaciens, two bacterial spacecraft contaminants known to replicate under low atmospheric pressures of 2.5 kPa, were tested for growth and survival under simulated Mars conditions. Environmental stresses of high salinity, low temperature, and low pressure were screened alone and in combination for effects on bacterial survival and replication, and then cells were tested in Mars analog soils under simulated Mars conditions. Survival and replication of E. coli and S. liquefaciens cells in liquid medium were evaluated for 7 days under low temperatures (5, 10, 20, or 30 degrees C) with increasing concentrations (0, 5, 10, or 20%) of three salts (MgCl(2), MgSO(4), NaCl) reported to be present on the surface of Mars. Moderate to high growth rates were observed for E. coli and S. liquefaciens at 30 or 20 degrees C and in solutions with 0 or 5% salts. In contrast, cell densities of both species generally did not increase above initial inoculum levels under the highest salt concentrations (10 and 20%) and the four temperatures tested, with the exception that moderately higher cell densities were observed for both species at 10% MgSO(4) maintained at 20 or 30 degrees C. Growth rates of E. coli and S. liquefaciens in low salt concentrations were robust under all pressures (2.5, 10, or 101.3 kPa), exhibiting a general increase of up to 2.5 orders of magnitude above the initial inoculum levels of the assays. Vegetative E. coli cells were maintained in a Mars analog soil for 7 days under simulated Mars conditions that included temperatures between 20 and -50 degrees C for a day/night diurnal period, UVC irradiation (200 to 280 nm) at 3.6 W m(-2) for daytime operations (8 h), pressures held at a constant 0.71 kPa, and a gas composition that included the top five gases found in the martian atmosphere. Cell densities of E. coli failed to increase under simulated Mars conditions, and survival was reduced 1 to 2 orders of magnitude by the interactive effects of desiccation, UV irradiation, high salinity, and low pressure (in decreasing order of importance). Results suggest that E. coli may be able to survive, but not grow, in surficial soils on Mars.

Sequestration of carbon dioxide and production of biomolecules using cyanobacteria.

PubMed

Upendar, Ganta; Singh, Sunita; Chakrabarty, Jitamanyu; Chandra Ghanta, Kartik; Dutta, Susmita; Dutta, Abhishek

2018-07-15

A cyanobacterial strain, Synechococcus sp. NIT18, has been applied to sequester CO 2 using sodium carbonate as inorganic carbon source due to its efficiency of CO 2 bioconversion and high biomass production. The biomass obtained is used for the extraction of biomolecules - protein, carbohydrate and lipid. The main objective of the study is to maximize the biomass and biomolecules production with CO 2 sequestration using cyanobacterial strain cultivated under different concentrations of CO 2 (5-20%), pH (7-11) and inoculum size (5-12.5%) within a statistical framework. Maximum sequestration of CO 2 and maximum productivities of protein, carbohydrate and lipid are 71.02%, 4.9 mg/L/day, 6.7 mg/L/day and 1.6 mg/L/day respectively, at initial CO 2 concentration: 10%, pH: 9 and inoculum size: 12.5%. Since flue gas contains 10-15% CO 2 and the present strain is able to sequester CO 2 in this range, the strain could be considered as a useful tool for CO 2 mitigation for greener world. Copyright © 2018 Elsevier Ltd. All rights reserved.

Effect of different fermentation parameters on L-lactic acid production from liquid distillery stillage.

PubMed

Djukić-Vuković, Aleksandra P; Mojović, Ljiljana V; Vukašinović-Sekulić, Maja S; Rakin, Marica B; Nikolić, Svetlana B; Pejin, Jelena D; Bulatović, Maja L

2012-09-15

Expansion of lactic acid applications, predominantly for the preparation of biodegradable polymers increased the research interest for new, economically favourable production processes. Liquid stillage from bioethanol production can be an inexpensive, valuable source of nutrients for growth of lactic acid bacteria. Utilisation of residual biomass with spent fermentation media as a functional animal feed can greatly influence the process value and its ecological aspect. In this paper, the kinetics of lactic acid and biomass production on liquid stillage by Lactobacillus rhamnosus ATCC 7469 was studied. In addition, the impact of temperature, inoculum concentration, shaking and pH control by addition of CaCO(3) was evaluated. Maximal lactic acid yield of 73.4%, as well as high biomass production (3×10(8) CFU ml(-1)) were achieved under selected conditions (41°C, 5% (v/v) of inoculum, 1% (w/v) of CaCO(3), initial pH of 6.5 and shaking rate of 90 rpm). These results were achieved without supplementation of the stillage with nitrogen or mineral sources. Copyright © 2012 Elsevier Ltd. All rights reserved.

Mutual facilitations of food waste treatment, microbial fuel cell bioelectricity generation and Chlorella vulgaris lipid production.

PubMed

Hou, Qingjie; Pei, Haiyan; Hu, Wenrong; Jiang, Liqun; Yu, Ze

2016-03-01

Food waste contains large amount of organic matter that may be troublesome for handing, storage and transportation. A microbial fuel cell (MFC) was successfully constructed with different inoculum densities of Chlorella vulgaris for promoting food waste treatment. Maximum COD removal efficiency was registered with 44% and 25 g CODL(-1)d(-1) of substrate degradation rate when inoculated with the optimal initial density (150 mg L(-1)) of C. vulgaris, which were 2.9 times and 3.1 times higher than that of the abiotic cathode. With the optimum inoculum density of C. vulgaris, the highest open circuit voltage, working voltage and power density of MFC were 260 mV, 170 mV and 19151 mW m(-3), respectively. Besides the high biodiesel quality, promoted by MFC stimulation the biomass productivity and highest total lipid content of C. vulgaris were 207 mg L(-1)d(-1) and 31%, which were roughly 2.7 times and 1.2 times higher than the control group. Copyright © 2015 Elsevier Ltd. All rights reserved.

Enhancement of 2,3-Butanediol Production by Klebsiella oxytoca PTCC 1402

PubMed Central

Anvari, Maesomeh; Safari Motlagh, Mohammad Reza

2011-01-01

Optimal operating parameters of 2,3-Butanediol production using Klebsiella oxytoca under submerged culture conditions are determined by using Taguchi method. The effect of different factors including medium composition, pH, temperature, mixing intensity, and inoculum size on 2,3-butanediol production was analyzed using the Taguchi method in three levels. Based on these analyses the optimum concentrations of glucose, acetic acid, and succinic acid were found to be 6, 0.5, and 1.0 (% w/v), respectively. Furthermore, optimum values for temperature, inoculum size, pH, and the shaking speed were determined as 37°C, 8 (g/L), 6.1, and 150 rpm, respectively. The optimal combinations of factors obtained from the proposed DOE methodology was further validated by conducting fermentation experiments and the obtained results revealed an enhanced 2,3-Butanediol yield of 44%. PMID:21318172

A simple and cost-saving approach to optimize the production of subtilisin NAT by submerged cultivation of Bacillus subtilis natto.

PubMed

Ku, Ting-Wei; Tsai, Ruei-Lan; Pan, Tzu-Ming

2009-01-14

Subtilisin NAT, formerly designated nattokinase or subtilisin BSP, is a potent cardiovascular drug because of its strong fibrinolytic activity and safety. In this study, one Bacillus subtilis natto strain with high fibrinolytic activity was isolated. We further studied the optimal conditions for subtilisin NAT production by submerged cultivation and three variables/three levels of response surface methodology (RSM) using various inoculum densities, glucose concentrations, and defatted soybean concentrations as the three variables. According to the RSM analysis, while culturing by 2.93% defatted soybean, 1.75% glucose, and 4.00% inoculum density, we obtained an activity of 13.78 SU/mL. Processing the batch fermentation with this optimal condition, the activity reached 13.69 SU/mL, which is equal to 99.3% of the predicted value.

Virulence of Meloidogyne spp. and Induced Resistance in Grape Rootstocks.

PubMed

McKenry, Michael V; Anwar, Safdar A

2007-03-01

Harmony grape rootstock displays resistance to several Meloidogyne spp. but that resistance is not durable in commercial vineyard settings. A 2-year experiment in a microplot setting revealed host specificities of two virulent populations of Meloidogyne arenaria and an avirulent population of Meloidogyne incognita. In a subsequent split-root experiment, the avirulent nematode population was demonstrated to induce resistance to the virulent nematode population. To quantify the level of resistance, reproduction of the virulent nematode population was determined 63 days after being challenged by an avirulent nematode population using a range of inoculum densities and timeframes. Induction of resistance became apparent when the virulent nematode population was inoculated 7 days after the avirulent nematode population and increased thereafter. The level of induced resistance increased with increased inoculum levels of the avirulent nematode population. Root systems of perennial crops are commonly fed upon simultaneously by multiple nematode species. These two studies indicate that field populations can become preferentially virulent upon one or multiple rootstocks and that co-inhabiting populations may induce existing resistance mechanisms. In perennial crops, it is common for numerous nematode species besides Meloidogyne spp. to be present, including some that feed without causing apparent damage.

Survival kinetics of Mycobacterium bovis during manufacture and ripening of raw milk Cheddar and Caerphilly cheese produced on a laboratory-scale.

PubMed

Forgrave, R; Donaghy, J A; Fisher, A; Rowe, M T

2016-11-01

Persistence of Mycobacterium bovis was investigated in UK raw milk cheeses. Replicating traditional cheese production methods under stringent CL3 containment conditions, Cheddar and Caerphilly cheeses were produced with Myco. bovis inoculated raw milk. High-inoculum investigations used three Myco. bovis genotypes; later low-inoculum investigations used only Myco. bovis AF2122/97. High-inoculum Cheddar (n = 9) and Caerphilly (n = 9) were matured for a minimum of 12 and 4 months respectively; maturation of low-inoculum Cheddar (n = 3) and Caerphilly (n = 3) was up to 11 weeks. Survival of Myco. bovis was monitored by enumeration at different points throughout cheese manufacture and ripening. D values were calculated as follows: 57 and 59 days in high-inoculum Cheddar and Caerphilly, respectively, and 41 and 24 days in low-inoculum Cheddar and Caerphilly respectively. Mycobacterium bovis is concentrated in cheese curd and a proportion lost with the whey. Reduction in viability during manufacturing is limited, while significant Myco. bovis inactivation occurs during maturation. Inactivation was improved, during Caerphilly ripening, when acid development was enhanced by increasing the proportion of starter culture. Mycobacterium bovis inactivation data obtained could be used to inform assessment of the risk posed to consumers by raw milk dairy products. © 2016 The Society for Applied Microbiology.

Antimicrobial Effects of β-Lactams on Imipenem-Resistant Ceftazidime-Susceptible Pseudomonas aeruginosa.

PubMed

Wi, Yu Mi; Choi, Ji-Young; Lee, Ji-Young; Kang, Cheol-In; Chung, Doo Ryeon; Peck, Kyong Ran; Song, Jae-Hoon; Ko, Kwan Soo

2017-06-01

We studied the resistance mechanism and antimicrobial effects of β-lactams on imipenem-resistant Pseudomonas aeruginosa isolates that were susceptible to ceftazidime as detected by time-kill curve methods. Among 215 P. aeruginosa isolates from hospitalized patients in eight hospitals in the Republic of Korea, 18 isolates (23.4% of 77 imipenem-resistant isolates) were imipenem resistant and ceftazidime susceptible. Multilocus sequence typing revealed diverse genotypes, which indicated independent emergence. These 18 isolates were negative for carbapenemase genes. All 18 imipenem-resistant ceftazidime-susceptible isolates showed decreased mRNA expression of oprD , and overexpression of mexB was observed in 13 isolates. In contrast, overexpression of ampC , mexD , mexF , or mexY was rarely found. Time-kill curve methods were applied to three selected imipenem-resistant ceftazidime-susceptible isolates at a standard inoculum (5 × 10 5 CFU/ml) or at a high inoculum (5 × 10 7 CFU/ml) to evaluate the antimicrobial effects of β-lactams. Inoculum effects were detected for all three β-lactam antibiotics, ceftazidime, cefepime, and piperacillin-tazobactam, against all three isolates. The antibiotics had significant killing effects in the standard inoculum, but no effects in the high inoculum were observed. Our results suggest that β-lactam antibiotics should be used with caution in patients with imipenem-resistant ceftazidime-susceptible P. aeruginosa infection, especially in high-inoculum infections such as endocarditis and osteomyelitis. Copyright © 2017 American Society for Microbiology.

Hydrogen production from sugar beet juice using an integrated biohydrogen process of dark fermentation and microbial electrolysis cell.

PubMed

Dhar, Bipro Ranjan; Elbeshbishy, Elsayed; Hafez, Hisham; Lee, Hyung-Sool

2015-12-01

An integrated dark fermentation and microbial electrochemical cell (MEC) process was evaluated for hydrogen production from sugar beet juice. Different substrate to inoculum (S/X) ratios were tested for dark fermentation, and the maximum hydrogen yield was 13% of initial COD at the S/X ratio of 2 and 4 for dark fermentation. Hydrogen yield was 12% of initial COD in the MEC using fermentation liquid end products as substrate, and butyrate only accumulated in the MEC. The overall hydrogen production from the integrated biohydrogen process was 25% of initial COD (equivalent to 6 mol H2/mol hexoseadded), and the energy recovery from sugar beet juice was 57% using the combined biohydrogen. Copyright © 2015 Elsevier Ltd. All rights reserved.

Different substrates and starter inocula govern microbial community structures in biogas reactors.

PubMed

Satpathy, Preseela; Steinigeweg, Sven; Cypionka, Heribert; Engelen, Bert

2016-01-01

The influence of different starter inocula on the microbial communities in biogas batch reactors fed with fresh maize and maize silage as substrates was investigated. Molecular biological analysis by Denaturing Gradient Gel Electrophoresis (DGGE) of 16S rRNA gene fragments showed that each inoculum bore specific microbial communities with varying predominant phylotypes. Both, bacterial and archaeal DGGE profiles displayed three distinct communities that developed depending on the type of inoculum. Although maize and silage are similar substrates, different communities dominated the lactate-rich silage compared to lactate-free fresh maize. Cluster analysis of DGGE gels showed the communities of the same substrates to be stable with their respective inoculum. Bacteria-specific DGGE analysis revealed a rich diversity with Firmicutes being predominant. The other abundant phylotypes were Bacteroidetes and Synergistetes. Archaea-specific DGGE analysis displayed less diverse community structures, identifying members of the Methanosarcinales as the dominant methanogens present in all the three biogas digesters. In general, the source of inoculum played a significant role in shaping microbial communities. Adaptability of the inoculum to the substrates fed also influenced community compositions which further impacted the rates of biogas production.

Effect of levels of wheat residue on the severity of stagonospora nodorum blotch in winter wheat

USDA-ARS?s Scientific Manuscript database

Stagonospora nodorum blotch (SNB), caused by the ascomycete fungus Stagonospora nodorum, is a major disease of wheat. Wheat residue can be an important source of inoculum, but the effect of different densities of infected debris on disease severity has not been previously determined. Experiments wer...

Seasonal trends in response to inoculation of coast live oak with Phytophthora ramorum

Treesearch

Richard S. Dodd; Daniel Hüberli; Tamar Y. Harnik; Brenda O' Dell; Matteo Garbelotto

2006-01-01

We developed a branch cutting inoculation method to provide a controlled system for studying variation in response to inoculation of coast live oak (Quercus agrifolia) with Phytophthora ramorum. This method has advantages over inoculations of trees in the field, in containing the inoculum and in allowing high levels of replication...

Utilization of tannery fleshings: Optimization of conditions for fermenting delimed tannery fleshings using Enterococcus faecium HAB01 by response surface methodology.

PubMed

Kumar Rai, Amit; General, Thiyam; Bhaskar, N; Suresh, P V; Sakhare, P Z; Halami, P M; Gowda, Lalitha R; Mahendrakar, N S

2010-03-01

Conditions for fermentation of delimed tannery fleshings--to obtain higher degree of protein hydrolysis and reasonably better antioxidant activity--using Enterococcus faecium HAB01 (GenBank #FJ418568) were optimized. Three independent variables--viz., inoculum level (X1), glucose level (X2) and fermentation time (X3)--were optimized using response surface method considering degree of hydrolysis (DH; %) and total titrable acidity (TTA) as response variables. The optimized conditions were found to be 12.5% (v/w) inoculum, 17.5% (w/w) glucose and 96h of fermentation at 37+/-1 degrees C to obtain a maximum DH%. The usefulness of the predicted model was further validated by considering random combinations of the independent factors. The chemical score of the hydrolysate revealed an excess amount of essential amino acids, viz., arginine and leucine compared to reference protein. The liquor portion had relatively high antioxidant activities, indicating its potential for use as a high value feed ingredient. Copyright (c) 2009 Elsevier Ltd. All rights reserved.

Enhancing the auto-flocculation of photosynthetic bacteria to realize biomass recovery in brewery wastewater treatment.

PubMed

Lu, Haifeng; Dong, Shan; Zhang, Guangming; Han, Ting; Zhang, Yuanhui; Li, Baoming

2018-02-15

Photosynthetic bacteria (PSB) wastewater treatment technology can simultaneously realize wastewater purification and biomass production. The produced biomass contains high value-added products, which can be used in medical and agricultural industry. However, because of the small size and high electronegativity, PSB are hard to be collected from wastewater, which hampers the commercialization of PSB-based industrial processes. Auto-flocculation is a low cost, energy saving, non-toxic biomass collection method for microbiology. In this work, the influence factors with their optimal levels and mechanism for enhancing the auto-flocculation of PSB were investigated in pure cultivation medium. Then PSB auto-flocculation performance in real brewery wastewater was probed. Results showed that Na + concentration, pH and light intensity were three crucial factors except the initial inoculum sizes and temperature. In the pure medium cultivation system, the optimal condition for PSB auto-flocculation was as follows: pH was 9.5, inoculum size was 420 mg l -1 , Na + concentration was 0.067 mol l -1 , light intensity was 5000 lux, temperature was 30°C. Under the optimal condition, the auto-flocculation ratio and biomass recovery reached 85.0% and 1488 mg l -1 , which improved by 1.67-fold and 2.14-fold compared with the PSB enrichment cultivation conditions, respectively. Mechanism analysis showed that the protein/polysaccharides ratio and absolute Zeta potential value had a liner relationship. For the brewery wastewater treatment, under the above optimal condition, the chemical oxygen demand removal reached 94.3% with the auto-flocculation ratio and biomass recovery of 89.6% and 1510 mg l -1 , which increased 2.75-fold and 2.77-fold, respectively.

A Tool for Investigating Asthma and COPD Exacerbations: A Newly Manufactured and Well Characterised GMP Wild-Type Human Rhinovirus for Use in the Human Viral Challenge Model

PubMed Central

Fullen, Daniel J.; Murray, Bryan; Mori, Julie; Catchpole, Andrew; Borley, Daryl W.; Murray, Edward J.; Balaratnam, Ganesh; Gilbert, Anthony; Mann, Alex; Hughes, Fiona; Lambkin-Williams, Rob

2016-01-01

Background Human Rhinovirus infection is an important precursor to asthma and chronic obstructive pulmonary disease exacerbations and the Human Viral Challenge model may provide a powerful tool in studying these and other chronic respiratory diseases. In this study we have reported the production and human characterisation of a new Wild-Type HRV-16 challenge virus produced specifically for this purpose. Methods and Stock Development A HRV-16 isolate from an 18 year old experimentally infected healthy female volunteer (University of Virginia Children’s Hospital, USA) was obtained with appropriate medical history and consent. We manufactured a new HRV-16 stock by minimal passage in a WI-38 cell line under Good Manufacturing Practice conditions. Having first subjected the stock to rigorous adventitious agent testing and determining the virus suitability for human use, we conducted an initial safety and pathogenicity clinical study in adult volunteers in our dedicated clinical quarantine facility in London. Human Challenge and Conclusions In this study we have demonstrated the new Wild-Type HRV-16 Challenge Virus to be both safe and pathogenic, causing an appropriate level of disease in experimentally inoculated healthy adult volunteers. Furthermore, by inoculating volunteers with a range of different inoculum titres, we have established the minimum inoculum titre required to achieve reproducible disease. We have demonstrated that although inoculation titres as low as 1 TCID50 can produce relatively high infection rates, the optimal titre for progression with future HRV challenge model development with this virus stock was 10 TCID50. Studies currently underway are evaluating the use of this virus as a challenge agent in asthmatics. Trial Registration ClinicalTrials.gov NCT02522832 PMID:27936016

Transmission of Phytophthora ramorum in Mixed-Evergreen Forest in California.

PubMed

Davidson, Jennifer M; Wickland, Allison C; Patterson, Heather A; Falk, Kristen R; Rizzo, David M

2005-05-01

ABSTRACT During 2001 to 2003, the transmission biology of Phytophthora ramorum, the causal agent of sudden oak death, was studied in mixedevergreen forest, a common forest type in northern, coastal California. Investigation of the sources of spore production focused on coast live oak (Quercus agrifolia) and bay laurel (Umbellularia californica), dominant hosts that comprised 39.7 and 46.2% of the individuals at the study site, respectively. All tests for inoculum production from the surface of infected coast live oak bark or exudates from cankers were negative. In contrast, sporangia and chlamydospores were produced on the surface of infected bay laurel leaves. Mean number of zoospores produced from infected bay laurel leaves under natural field conditions during rainstorms was 1,173.0 +/- SE 301.48, and ranged as high as 5,200 spores/leaf. P. ramorum was recovered from rainwater, soil, litter, and streamwater during the mid- to late rainy season in all 3 years of the study. P. ramorum was not recovered from sporadic summer rains or soil and litter during the hot, dry summer months. Concentrations of inoculum in rainwater varied significantly from year to year and increased as the rainy season progressed for the two complete seasons that were studied. Potential dispersal distances were investigated for rainwater, soil, and streamwater. In rainwater, inoculum moved 5 and 10 m from the inoculum source. For soil, transmission of inoculum was demonstrated from infested soil to bay laurel green leaf litter, and from bay laurel green leaf litter to aerial leaves of bay laurel seedlings. One-third to one-half of the hikers tested at the study site during the rainy season also were carrying infested soil on their shoes. In streamwater, P. ramorum was recovered from an unforested site in pasture 1 km downstream of forest with inoculum sources. In total, these studies provide details on the production and spread of P. ramorum inoculum in mixed-evergreen forest to aid forecasting and managing disease transmission of this environmentally destructive pathogen.

[Effect of inoculum size on sensitivity and specificity of the double-disk synergy test for the detection of wide-spectrum beta-lactamases].

PubMed

Bedenić, B; Boras, A

2001-01-01

The plasmid-mediated extended-spectrum beta-lactamases (ESBL) confer resistance to oxymino-cephalosporins, such as cefotaxime, ceftazidime, and ceftriaxone and to monobactams such as aztreonam. It is well known fact that ESBL producing bacteria exhibit a pronounced inoculum effect against broad spectrum cephalosporins like ceftazidime, cefotaxime, ceftriaxone and cefoperazone. The aim of this investigation was to determine the effect of inoculum size on the sensitivity and specificity of double-disk synergy test (DDST) which is the test most frequently used for detection of ESBLs, in comparison with other two methods (determination of ceftazidime MIC with and without clavulanate and inhibitor potentiated disk-diffusion test) which are seldom used in clinical laboratories. The experiments were performed on a set of K. pneumoniae strains with previously characterized beta-lactamases which comprise: 10 SHV-5 beta-lactamase producing K. pneumoniae, 20 SHV-2 + 1 SHV 2a beta-lactamase producing K. pneumoniae, 7 SHV-12 beta-lactamase producing K. pneumoniae, 39 putative SHV ESBL producing K. pneumoniae and 26 K. pneumoniae isolates highly susceptible to ceftazidime according to Kirby-Bauer disk-diffusion method and thus considered to be ESBL negative. According to the results of this investigation, increase in inoculum size affected more significantly the sensitivity of DDST than of other two methods. The sensitivity of the DDST was lower when a higher inoculum size of 10(8) CFU/ml was applied, in distinction from other two methods (MIC determination and inhibitor potentiated disk-diffusion test) which retained high sensitivity regardless of the density of bacterial suspension. On the other hand, DDST displayed higher specificity compared to other two methods regardless of the inoculum size. This investigation found that DDST is a reliable method but it is important to standardize the inoculum size.

Characterization of Founder Viruses in Very Early SIV Rectal Transmission

PubMed Central

Yuan, Zhe; Ma, Fangrui; Demers, Andrew J.; Wang, Dong; Xu, Jianqing; Lewis, Mark G.; Li, Qingsheng

2016-01-01

A better understanding of HIV-1 transmission is critical for developing preventative strategies. To that end, we analyzed 524 full-length env sequences of SIVmac251 at 6 and 10 days post intrarectal infection of rhesus macaques. There was no tissue compartmentalization of founder viruses across plasma, rectal and distal lymphatic tissues for most animals; however one animal has evidence of virus tissue compartmentalization. Despite identical viral inoculums, founder viruses were animal-specific, primarily derived from rare variants in the inoculum, and have a founder virus signature that can distinguish dominant founder variants from minor founder or untransmitted variants in the inoculum. Importantly, the sequences of post-transmission defective viruses were phylogenetically associated with competent viral variants in the inoculum and were mainly converted from competent viral variants by frameshift rather than APOBEC mediated mutations, suggesting the converting the transmitted viruses into defective viruses through frameshift mutation is an important component of rectal transmission bottleneck. PMID:28027479

Influence of inoculum size of Aspergillus parasiticus spores on aflatoxin production

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharma, A.; Behere, A.G.; Padwal-Desai, S.R.

The influence of the inoculum size on growth and aflatoxin production was examined in Aspergillus parasiticus (NRRL 3145) by using a synthetic medium. The reduction in the number of spores by 4 to 5 log cycles either by serial dilution or by gamma irradiation caused a two fold increase in the toxin production. The decrease in the inoculum size induced a lag in growth of the culture, though the final yield of the mycelium over the 28-day experimental period was the same. The maximal accumulation of aflatoxin was observed on day 14 of incubation. A transition from the biphasic tomore » monophasic pattern in aflatoxin production could be correlated with the size of the inoculum. The enhanced toxin production from dilute inocula was similar to that obtained with the surviving fraction of the spores after gamma irradiation (0 to 150 krads).« less

Evaluation of lactic acid as an initial and secondary subprimal intervention for Escherichia coli O157:H7, non-O157 Shiga toxin-producing E. coli, and a nonpathogenic E. coli surrogate for E. coli O157:H7.

PubMed

Pittman, C I; Geornaras, I; Woerner, D R; Nightingale, K K; Sofos, J N; Goodridge, L; Belk, K E

2012-09-01

Lactic acid can reduce microbial contamination on beef carcass surfaces when used as a food safety intervention, but effectiveness when applied to the surface of chilled beef subprimal sections is not well documented. Studies characterizing bacterial reduction on subprimals after lactic acid treatment would be useful for validations of hazard analysis critical control point (HACCP) systems. The objective of this study was to validate initial use of lactic acid as a subprimal intervention during beef fabrication followed by a secondary application to vacuum-packaged product that was applied at industry operating parameters. Chilled beef subprimal sections (100 cm(2)) were either left uninoculated or were inoculated with 6 log CFU/cm(2) of a 5-strain mixture of Escherichia coli O157:H7, a 12-strain mixture of non-O157 Shiga toxin-producing E. coli (STEC), or a 5-strain mixture of nonpathogenic (biotype I) E. coli that are considered surrogates for E. coli O157:H7. Uninoculated and inoculated subprimal sections received only an initial or an initial and a second "rework" application of lactic acid in a custombuilt spray cabinet at 1 of 16 application parameters. After the initial spray, total inoculum counts were reduced from 6.0 log CFU/cm(2) to 3.6, 4.4, and 4.4 log CFU/cm(2) for the E. coli surrogates, E. coli O157:H7, and non-O157 STEC inoculation groups, respectively. After the second (rework) application, total inoculum counts were 2.6, 3.2, and 3.6 log CFU/cm(2) for the E. coli surrogates, E. coli O157:H7, and non-O157 STEC inoculation groups, respectively. Both the initial and secondary lactic acid treatments effectively reduced counts of pathogenic and nonpathogenic strains of E. coli and natural microflora on beef subprimals. These data will be useful to the meat industry as part of the HACCP validation process.

Seasonal associations and atmospheric transport distances of fungi in the genus Fusarium collected with unmanned aerial vehicles and ground-based sampling devices

NASA Astrophysics Data System (ADS)

Lin, Binbin; Ross, Shane D.; Prussin, Aaron J.; Schmale, David G.

2014-09-01

Spores of fungi in the genus Fusarium may be transported through the atmosphere over long distances. New information is needed to characterize seasonal trends in atmospheric loads of Fusarium and to pinpoint the source(s) of inoculum at both local (farm) and regional (state or country) scales. We hypothesized that (1) atmospheric concentrations of Fusarium spores in an agricultural ecosystem vary with height and season and (2) transport distances from potential inoculum source(s) vary with season. To test these hypotheses, spores of Fusarium were collected from the atmosphere in an agricultural ecosystem in Blacksburg, VA, USA using a Burkard volumetric sampler (BVS) 1 m above ground level and autonomous unmanned aerial vehicles (UAVs) 100 m above ground level. More than 2200 colony forming units (CFUs) of Fusarium were collected during 104 BVS sampling periods and 180 UAV sampling periods over four calendar years (2009-2012). Spore concentrations ranged from 0 to 13 and 0 to 23 spores m-3 for the BVS and the UAVs, respectively. Spore concentrations were generally higher in the fall, spring, and summer, and lower in the winter. Spore concentrations from the BVS were generally higher than those from the UAVs for both seasonal and hourly collections. A Gaussian plume transport model was used to estimate distances to the potential inoculum source(s) by season, and produced mean transport distances of 1.4 km for the spring, 1.7 km for the summer, 1.2 km for the fall, and 4.1 km for the winter. Environmental signatures that predict atmospheric loads of Fusarium could inform disease spread, air pollution, and climate change.

Biodegradation of hydrocarbon mixtures in surface waters at environmentally relevant levels - Effect of inoculum origin on kinetics and sequence of degradation.

PubMed

Birch, Heidi; Hammershøj, Rikke; Comber, Mike; Mayer, Philipp

2017-10-01

Biodegradation is a dominant removal process for many organic pollutants, and biodegradation tests serve as tools for assessing their environmental fate within regulatory risk assessment. In simulation tests, the inoculum is not standardized, varying in microbial quantity and quality, thereby potentially impacting the observed biodegradation kinetics. In this study we investigated the effect of inoculum origin on the biodegradation kinetics of hydrocarbons for five inocula from surface waters varying in urbanization and thus expected pre-exposure to petroleum hydrocarbons. A new biodegradation method for testing mixtures of hydrophobic chemicals at trace concentrations was demonstrated: Aqueous solutions containing 9 hydrocarbons were generated by passive dosing and diluted with surface water resulting in test systems containing native microorganisms exposed to test substances at ng-μg/L levels. Automated Headspace Solid Phase Microextraction coupled to GC-MS was applied directly to these test systems to determine substrate depletion relative to abiotic controls. Lag phases were generally less than 8 days. First order rate constants were within one order of magnitude for each hydrocarbon in four of the five waters but lower in water from a rural lake. The sequence of degradation between the 9 hydrocarbons showed similar patterns in the five waters indicating the potential for using selected hydrocarbons for benchmarking between biodegradation tests. Degradation half-times were shorter than or within one order of magnitude of BioHCwin predictions for 8 of 9 hydrocarbons. These results showed that location choice is important for biodegradation kinetics and can provide a relevant input to aquatic exposure and fate models. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of domestication on microorganism diversity and anaerobic digestion of food waste.

PubMed

Bi, S J; Hong, X J; Wang, G X; Li, Y; Gao, Y M; Yan, L; Wang, Y J; Wang, W D

2016-08-19

To accomplish the rapid start-up and stable operation of biogas digesters, an efficient inoculum is required. To obtain such an inoculum for food waste anaerobic digestion, we domesticated dairy manure anaerobic digestion residue by adding food waste every day. After 36 days, the pH and biogas yield stabilized signifying the completion of domestication. During domestication, the microbial communities in the inocula were investigated by constructing 16S rDNA clone libraries. We evaluated the effect of the domesticated inoculum by testing batch food waste anaerobic digestion with a non-domesticated inoculum as a control. The pH and methane yield of the digestion systems were determined as measurement indices. Domestication changed the composition and proportion of bacteria and archaea in the inocula. Of the bacteria, Clostridia (49.3%), Bacteroidales (19.5%), and Anaerolinaceae (8.1%) species were dominant in the seed sludge; Anaerolinaceae (49.0%), Clostridia (28.4%), and Bacteroidales (9.1%), in domestication sludge. Methanosaeta was the dominant genus in both of the seed (94.3%) and domestication (74.3%) sludge. However, the diversity of methanogenic archaea was higher in the domestication than in seed sludge. Methanoculleus, which was absent from the seed sludge, appeared in the domestication sludge (21.7%). When the domesticated inoculum was used, the digestion system worked stably (organic loading rate: 20 gVS/L; methane yield: 292.2 ± 9.8 mL/gVS; VS = volatile solids), whereas the digestion system inoculated with seed sludge failed to generate biogas. The results indicate that inoculum domestication ensures efficient and stable anaerobic digestion by enriching the methanogenic strains.

Effectiveness of a model constructed wetland system containing Cyperus papyrus in degrading diesel oil

NASA Astrophysics Data System (ADS)

Harbowo, Danni Gathot; Choesin, Devi Nandita

2014-03-01

Synergism between wetland systems and the provision of degrading bacterial inoculum is now being developed for the recovery of areas polluted waters of pollutants. In connection with the frequent cases of diesel oil pollution in the waters of Indonesia, we need a way of water treatment as an efficient. In this study conducted a series of tests to develop an construcred wetland design that can effectively degrade diesel oil. Tested five systems: blanko (A), substrated, without bacterial inoculums, and vegetation (B); with the addition of inoculum (C); subsrated and vegetated (D); substrated and vegetated with the addition of inoculum (E). Vegetation used in this study is Cyperus papyrus because it has the ability to absorb pollutants. Inoculum used was Pseudomonas aeruginosa and Enterobacter aerogenes which is a bacteria degrading organic compounds commonly found in water. To measure the effectiveness of the system, use several indicators to see the degradation of pollutants, namely changes in viscosity, surface tension of pollutants, and the emergence of compound degradation. Based on the results of the study can be determined that the substrated and vegetated system with Cyperus papyrus inoculum (E) was considered the most capable of degrading diesel oil due to the large changes in all parameters. In the system E, 40.6% increase viscosity, surface tension decreased 32.7%, the appearance of degradation compounds with relatively 3614.7 points, and increased to 227.8% TDS. In addition the environmental conditions in the system E also supports the growth of vegetation and degrading microbes.

Rapid Detection of Ceratocystis platani Inoculum by Quantitative Real-Time PCR Assay

PubMed Central

Ghelardini, Luisa; Belbahri, Lassaâd; Quartier, Marion; Santini, Alberto

2013-01-01

Ceratocystis platani is the causal agent of canker stain of plane trees, a lethal disease able to kill mature trees in one or two successive growing seasons. The pathogen is a quarantine organism and has a negative impact on anthropogenic and natural populations of plane trees. Contaminated sawdust produced during pruning and sanitation fellings can contribute to disease spread. The goal of this study was to design a rapid, real-time quantitative PCR assay to detect a C. platani airborne inoculum. Airborne inoculum traps (AITs) were placed in an urban setting in the city of Florence, Italy, where the disease was present. Primers and TaqMan minor groove binder (MGB) probes were designed to target cerato-platanin (CP) and internal transcribed spacer 2 (ITS2) genes. The detection limits of the assay were 0.05 pg/μl and 2 fg/μl of fungal DNA for CP and ITS, respectively. Pathogen detection directly from AITs demonstrated specificity and high sensitivity for C. platani, detecting DNA concentrations as low as 1.2 × 10−2 to 1.4 × 10−2 pg/μl, corresponding to ∼10 conidia per ml. Airborne inoculum traps were able to detect the C. platani inoculum within 200 m of the closest symptomatic infected plane tree. The combination of airborne trapping and real-time quantitative PCR assay provides a rapid and sensitive method for the specific detection of a C. platani inoculum. This technique may be used to identify the period of highest risk of pathogen spread in a site, thus helping disease management. PMID:23811499

Analyses of Fusarium wilt race 3 resistance in Upland cotton (Gossypium hirsutum L.).

PubMed

Abdullaev, Alisher A; Salakhutdinov, Ilkhom B; Egamberdiev, Sharof Sh; Kuryazov, Zarif; Glukhova, Ludmila A; Adilova, Azoda T; Rizaeva, Sofiya M; Ulloa, Mauricio; Abdurakhmonov, Ibrokhim Y

2015-06-01

Fusarium wilt [Fusarium oxysporum f.sp. vasinfectum (FOV) Atk. Sny & Hans] represents a serious threat to cotton (Gossypium spp.) production. For the last few decades, the FOV pathogen has become a significant problem in Uzbekistan causing severe wilt disease and yield losses of G. hirsutum L. cultivars. We present the first genetic analyses of FOV race 3 resistance on Uzbek Cotton Germplasm with a series of field and greenhouse artificial inoculation-evaluations and inheritance studies. The field experiments were conducted in two different sites: the experimental station in Zangiota region-Environment (Env) 1 and the Institute of Cotton Breeding (Env-2, Tashkent province). The Env-1 was known to be free of FOV while the Env-2 was known to be a heavily FOV infested soil. In both (Env-1 and Env-2) of these sites, field soil was inoculated with FOV race 3. F2 and an F3 Upland populations ("Mebane B1" × "11970") were observed with a large phenotypic variance for plant survival and FOV disease severity within populations and among control or check Upland accessions. Wilt symptoms among studied F2 individuals and F3 families significantly differed depending on test type and evaluation site. Distribution of Mendelian rations of susceptible (S) and resistant (R) phenotypes were 1S:1R field Env-1 and 3S:1R field Env-2 in the F2 population, and 1S:3R greenhouse site in the F3 population. The different segregation distribution of the Uzbek populations may be explained by differences in FOV inoculum level and environmental conditions during assays. However, genetic analysis indicated a recessive single gene action under high inoculum levels or disease pressure for FOV race 3 resistance. Uzbek germplasm may be more susceptible than expected to FOV race 3, and sources of resistance to FOV may be limited under the FOV inoculum levels present in highly-infested fields making the breeding process more complex.

Fate of Listeria monocytogenes in Fresh Apples and Caramel Apples.

PubMed

Salazar, Joelle K; Carstens, Christina K; Bathija, Vriddi M; Narula, Sartaj S; Parish, Mickey; Tortorello, Mary Lou

2016-05-01

An outbreak of listeriosis in late 2014 and early 2015 associated with caramel apples led to questions about how this product became a vector for Listeria monocytogenes. This investigation aimed to determine information about the survival and growth of L. monocytogenes in both fresh apples and caramel apples, specifically examining the effects of site and level of inoculation, inoculum drying conditions, and storage temperature. At a high inoculation level (7 log CFU per apple), L. monocytogenes inoculated at the stem end proliferated on Gala caramel apples at both 5 and 25°C and on Granny Smith caramel apples at 25°C by as much as 3 to 5 log CFU per apple. Fresh apples and caramel apples inoculated at the equatorial surface supported survival but not growth of the pathogen. Growth rates (μmax) for apples inoculated at the stem end, as determined using the Baranyi and Roberts growth model, were 1.64 ± 0.27 and 1.38 ± 0.20 log CFU per apple per day for Gala and Granny Smith caramel apples, respectively, stored at 25°C. At a low inoculation level (3 log CFU per apple), L. monocytogenes inoculated at the stem end and the equatorial surface survived but did not grow on fresh Gala and Granny Smith apples stored at 25°C for 49 days; however, on caramel apples inoculated at the stem end, L. monocytogenes had significant growth under the same conditions. Although certain conditions did not support growth, the pathogen was always detectable by enrichment culture. The inoculation procedure had a significant effect on results; when the inoculum was allowed to dry for 24 h at 5°C, growth was significantly slowed compared with inoculum allowed to dry for 2 h at 25°C. Variation in stick materials did affect L. monocytogenes survival, but these differences were diminished once sticks were placed into caramel apples.

The effect of low-temperature laundering and detergents on the survival of Escherichia coli and Staphylococcus aureus on textiles used in healthcare uniforms.

PubMed

Riley, K; Williams, J; Owen, L; Shen, J; Davies, A; Laird, K

2017-05-10

To determine the survival of Escherichia coli and Staphylococcus aureus on cotton and polyester and the effectiveness of low-temperature laundering and detergents on the removal of micro-organism from healthcare laundry. Survival of E. coli and S. aureus on polyester or cotton was assessed over 3 weeks and the efficacy of a domestic wash (40 and 60°C) and a range of detergents was also determined. Both bacteria were able to survive on cotton (5 log (10) ) and polyester (0·28 log (10) ) for up to 3 weeks. Laundering at 40°C resulted in a 3·5 log (10) removal of the initial 7·7 log (10) inoculum and some cross-contamination to sterile fabrics (3 log (10) ). Increasing the temperature to 60°C resulted in the complete removal of the initial inoculum. This study shows that most of the micro-organisms are removed at 40°C, however, those cells still remaining may have the potential for further contamination to the clinical environment and patients. National Health Service (NHS) nurses are required to domestically launder their uniforms at 60°C to ensure safe removal of micro-organisms, 33% of NHS staff questioned said they launder their uniforms at 40°C, which could potentially result in transmission of hospital-acquired infections. © 2017 The Society for Applied Microbiology.

Optimization of medium components and cultural variables for enhanced production of acidic high maltose-forming and Ca2+-independent α-amylase by Bacillus acidicola.

PubMed

Sharma, Archana; Satyanarayana, Tulasi

2011-05-01

The production of acidic α-amylase by a novel acidophilic bacterium Bacillus acidicola TSAS1 was optimized in submerged fermentation using statistical approaches. The process parameters that significantly affected α-amylase production (starch, K(2)HPO(4), inoculum size and temperature) were identified by Plackett and Burman design. The optimum levels of the significant variables as determined using central composite design of response surface methodology are starch (2.75%), K(2)HPO(4) (0.01%), inoculum size [2% (v/v) containing 1.9×10(8) CFU ml(-1)], and temperature (33°C). An overall 2.4 and 2.9-fold increase in enzyme production has been attained in batch and fed-batch fermentations in the laboratory fermentor, respectively. Copyright © 2011 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Enrichment of Secondary Wastewater Sludge for Production of Hydrogen from Crude Glycerol and Comparative Evaluation of Mono-, Co- and Mixed-Culture Systems

PubMed Central

Pachapur, Vinayak Laxman; Kutty, Prianka; Brar, Satinder Kaur; Ramirez, Antonio Avalos

2016-01-01

Anaerobic digestion using mixed-culture with broader choice of pretreatments for hydrogen (H2) production was investigated. Pretreatment of wastewater sludge by five methods, such as heat, acid, base, microwave and chloroform was conducted using crude glycerol (CG) as substrate. Results for heat treatment (100 °C for 15 min) showed the highest H2 production across the pretreatment methods with 15.18 ± 0.26 mmol/L of medium at 30 °C in absence of complex media and nutrient solution. The heat-pretreated inoculum eliminated H2 consuming bacteria and produced twice as much as H2 as compared to other pretreatment methods. The fermentation conditions, such as CG concentration (1.23 to 24 g/L), percentage of inoculum size (InS) (1.23% to 24% v/v) along with initial pH (2.98 to 8.02) was tested using central composite design (CCD) with H2 production as response parameter. The maximum H2 production of 29.43 ± 0.71 mmol/L obtained at optimum conditions of 20 g/L CG, 20% InS and pH 7. Symbiotic correlation of pH over CG and InS had a significant (p-value: 0.0011) contribution to H2 production. The mixed-culture possessed better natural acclimatization activity for degrading CG, at substrate inhibition concentration and provided efficient inoculum conditions in comparison to mono- and co-culture systems. The heat pretreatment step used across mixed-culture system is simple, cheap and industrially applicable in comparison to mono-/co-culture systems for H2 production. PMID:26771607

Aerobic and anaerobic degradation and mineralization of 14C-chitin by water column and sediment inocula of the York River estuary, Virginia.

PubMed Central

Boyer, J N

1994-01-01

Potential rates of chitin degradation (Cd) and mineralization (Cm) by estuarine water and sediment bacteria were measured as a function of inoculum source, temperature, and oxygen condition. In the water column inoculum, 88 to 93% of the particulate chitin was mineralized to CO2 with no apparent lag between degradation and mineralization. No measurable dissolved pool of radiolabel was found in the water column. For the sediment inocula, 70 to 90% of the chitin was degraded while only 55 to 65% was mineralized to CO2. 14C label recoveries in the dissolved pool were 19 to 21% for sand, 17 to 24% in aerobic mud, and 12 to 21% for the anaerobic mud. This uncoupling between degradation and mineralization occurred in all sediment inocula. More than 98% of the initial 14C-chitin was recovered in the three measured fractions. The highest Cd and Cm values, 30 and 27% day-1, occurred in the water column inoculum at 25 degrees C. The lowest Cd and Cm values were found in the aerobic and anaerobic mud inocula incubated at 15 degrees C. Significant differences in Cd and Cm values among water column and sediment inocula as well as between temperature treatments were evident. An increased incubation temperature resulted in shorter lag times before the onset of chitinoclastic bacterial growth, degradation, and mineralization and resulted in apparent Q10 values of 1.1 for water and 1.3 to 2.1 for sediment inocula. It is clear that chitin degradation and mineralization occur rapidly in the estuary and that water column bacteria may be more important in this process than previously acknowledged. PMID:8117075

Soil moisture--a regulator of arbuscular mycorrhizal fungal community assembly and symbiotic phosphorus uptake.

PubMed

Deepika, Sharma; Kothamasi, David

2015-01-01

Multiple species of arbuscular mycorrhizal fungi (AMF) can colonize roots of an individual plant species but factors which determine the selection of a particular AMF species in a plant root are largely unknown. The present work analysed the effects of drought, flooding and optimal soil moisture (15-20 %) on AMF community composition and structure in Sorghum vulgare roots, using PCR-RFLP. Rhizophagus irregularis (isolate BEG 21), and rhizosphere soil (mixed inoculum) of Heteropogon contortus, a perennial C4 grass, collected from the semi-arid Delhi ridge, were used as AMF inocula. Soil moisture functioned as an abiotic filter and affected AMF community assembly inside plant roots by regulating AMF colonization and phylotype diversity. Roots of plants in flooded soils had lowest AMF diversity whilst root AMF diversity was highest under the soil moisture regime of 15-20 %. Although plant biomass was not affected, root P uptake was significantly influenced by soil moisture. Plants colonized with R. irregularis or mixed AMF inoculum showed higher root P uptake than non-mycorrhizal plants in drought and control treatments. No differences in root P levels were found in the flooded treatment between plants colonized with R. irregularis and non-mycorrhizal plants, whilst under the same treatment, root P uptake was lower in plants colonized with mixed AMF inoculum than in non-mycorrhizal plants.

Root infections may challenge management of invasive Phytophthora spp

Treesearch

E.J. Fichtner; D.M. Rizzo; S.A. Kirk; J.F. Webber

2011-01-01

Because sporulation of Phytophthora ramorum and P. kernoviae on Rhododendron ponticum, an invasive plant, serves as primary inoculum for trunk infections on trees, R. ponticum clearance from pathogen-infested woodlands is pivotal to inoculum management. The efficacy of clearance for...

Inoculum and zeolite synergistic effect on anaerobic digestion of poultry manure.

PubMed

Fotidis, Ioannis A; Kougias, Panagiotis G; Zaganas, Ioannis D; Kotsopoulos, Thomas A; Martzopoulos, Gerasimos G

2014-01-01

Poultry manure is an ammonia-rich substrate due to its high content of proteins and amino acids. Ammonia is the major inhibitor of anaerobic digestion (AD) process, affecting biogas production and causing great economic losses to the biogas plants. In this study, the effect of different natural zeolite dosages on the mesophilic AD of poultry manure inoculated with a non-acclimatized to ammonia inoculum (dairy manure) was investigated. Additionally, a comparative analysis was performed between the data extracted from this study and the results of a previous study, which has been conducted under the same experimental conditions but with the use of ammonia acclimatized inoculum (swine manure). At 5 and 10 g zeolite L(-1), the methane yield of poultry manure was 43.4% and 80.3% higher compared with the experimental set without zeolite addition. However, the ammonia non-acclimatized inoculum was not efficient in digesting poultry manure even in the presence of 10 g zeolite L(-1), due to low methane production (only 39%) compared with the maximum theoretical yield. Finally, ammonia acclimatized inoculum and zeolite have demonstrated a possible 'synergistic effect', which led to a more efficient AD of poultry manure. The results of this study could potentially been used by the biogas plant operators to efficiently digest poultry manure.

Effects of Feedstock Sources on Inoculant Acclimatization: Start-up Strategies and Reactor Performance.

PubMed

Yang, Qian; Wei, Liang-Huan; Li, Wei-Zun; Chen, Yu; Ju, Mei-Ting

2017-11-01

Different inoculum sources and acclimatization methods result in different substrate adaptation and biodegradability. To increase straw degradation rate, shorten the digester start-up time, and enhance the biogas production, we domesticated anaerobic sludge by adding microcrystalline cellulose (MCC). During acclimatization, the start-up strategies and reactor performance were investigated to analyze changes in feedstock adaption, biodegradability, and methanogen activity. The effect of the domesticated inoculum was evaluated by testing batch un-pretreated corn stover with a dewatered sludge (DS)-domesticated inoculum as a control. The results showed that (1) using MCC as a substrate rapidly improved microorganism biodegradability and adaptation. (2) MCC as domesticated substrate has relatively stable system and high mass conversion, but with low buffer capacity. (3) Macro- and micronutrients should be added for improving the activity of methanogenic and system's buffer capacity. (4) Using the domesticated inoculums and batch tests to anaerobically digest untreated corn stover yielded rapid biogas production of 292 mL, with an early peak value on the first day. The results indicated that cultivating directional inoculum can efficiently and quickly start-up digester. These investigated results to promote anaerobic digestion of straw for producing biogas speed up the transformation of achievements of biomass solid waste utilization have a positive promoting significance.

The water kefir grain inoculum determines the characteristics of the resulting water kefir fermentation process.

PubMed

Laureys, D; De Vuyst, L

2017-03-01

To investigate the influence of the water kefir grain inoculum on the characteristics of the water kefir fermentation process. Three water kefir fermentation processes were started with different water kefir grain inocula and followed as a function of time regarding microbial species diversity, community dynamics, substrate consumption profile and metabolite production course. The inoculum determined the water kefir grain growth, the viable counts on the grains, the time until total carbohydrate exhaustion, the final metabolite concentrations and the microbial species diversity. There were always 2-10 lactic acid bacterial cells for every yeast cell and the majority of these micro-organisms was always present on the grains. Lactobacillus paracasei, Lactobacillus hilgardii, Lactobacillus nagelii and Saccharomyces cerevisiae were always present and may be the key micro-organisms during water kefir fermentation. Low water kefir grain growth was associated with small grains with high viable counts of micro-organisms, fast fermentation and low pH values, and was not caused by the absence of exopolysaccharide-producing lactic acid bacteria. The water kefir grain inoculum influences the microbial species diversity and characteristics of the fermentation process. A select group of key micro-organisms was always present during fermentation. This study allows a rational selection of a water kefir grain inoculum. © 2016 The Society for Applied Microbiology.

Rapid Induction of High-Level Carbapenem Resistance in Heteroresistant KPC-Producing Klebsiella pneumoniae

PubMed Central

Adams-Sapper, Sheila; Nolen, Shantell; Donzelli, Grace Fox; Lal, Mallika; Chen, Kunihiko; Justo da Silva, Livia Helena; Moreira, Beatriz M.

2015-01-01

Enterobacteriaceae strains producing the Klebsiella pneumoniae carbapenemase (KPC) have disseminated worldwide, causing an urgent threat to public health. KPC-producing strains often exhibit low-level carbapenem resistance, which may be missed by automated clinical detection systems. In this study, eight Klebsiella pneumoniae strains with heterogeneous resistance to imipenem were used to elucidate the factors leading from imipenem susceptibility to high-level resistance as defined by clinical laboratory testing standards. Time-kill analysis with an inoculum as low as 3 × 106 CFU/ml and concentrations of imipenem 8- and 16-fold higher than the MIC resulted in the initial killing of 99.9% of the population. However, full recovery of the population occurred by 20 h of incubation in the same drug concentrations. Population profiles showed that recovery was mediated by a heteroresistant subpopulation at a frequency of 2 × 10−7 to 3 × 10−6. Samples selected 2 h after exposure to imipenem were as susceptible as the unexposed parental strain and produced the major outer membrane porin OmpK36. However, between 4 to 8 h after exposure, OmpK36 became absent, and the imipenem MIC increased at least 32-fold. Individual colonies isolated from cultures after 20 h of exposure revealed both susceptible and resistant subpopulations. Once induced, however, the high-level imipenem resistance was maintained, and OmpK36 remained unexpressed even without continued carbapenem exposure. This study demonstrates the essential coordination between blaKPC and ompK36 expression mediating high-level imipenem resistance from a population of bacteria that initially exhibits a carbapenem-susceptibility phenotype. PMID:25801565

Identification of alleles conferring resistance to gray leaf spot in maize derived from its wild progenitor species teosinte (Zea mays ssp. parviglumis)

USDA-ARS?s Scientific Manuscript database

Gray Leaf Spot [(GLS), causal agent Cercospora zeae-maydis and Cercospora zeina] is an important maize disease in the United States. Current control methods for GLS include using resistant cultivars, crop rotation, chemical applications, and conventional tillage to reduce inoculum levels. Teosinte ...

A test system to quantify inoculum in runoff from Phytophthora ramorum-infected plant roots

Treesearch

Nina. Shishkoff

2010-01-01

Foliar hosts of Phytophthora ramorum are often susceptible to root infection, but the epidemiological significance of such infections is unknown. We used a standardized test system to study inoculum in runoff from root-infected Viburnum tinus cuttings.

A bench-scale, cost effective and simple method to elicit Lycopersicon esculentum cv. PKM1 (tomato) plants against Cucumber mosaic virus attack using ozone-mediated inactivated Cucumber mosaic virus inoculum.

PubMed

Sudhakar, N; Nagendra-Prasad, D; Mohan, N; Murugesan, K

2007-12-01

Studies were undertaken to evaluate ozone for inactivation of Cucumber mosaic virus present in the inoculum and to stimulate Lycopersicon esculentum cv. PKM1 (tomato) plants against Cucumber mosaic virus infection by using the inactivated Cucumber mosaic virus inoculum. Application of a T(4) (0.4mg/l) concentration of ozone to the inoculum containing Cucumber mosaic virus resulted in complete inactivation of the virus. The inactivated viral inoculum was mixed with a penetrator (delivery agent), referred to as T(4) preparation, and it was evaluated for the development of systemic acquired resistance in the tomato plants. Application of a T(4) preparation 5 days before inoculation with the Cucumber mosaic virus protected tomato plants from the effects of Cucumber mosaic virus. Among the components of the inactivated virus tested, coat protein subunits and aggregates were responsible for the acquired resistance in tomato plants. In field trials, the results of enzyme-linked immunosorbent assay revealed that, Cucumber mosaic virus accumulation was significantly less for all the test plants (16%) sprayed with the T(4) preparation than untreated control plants (89.5%) at 28 days postinoculation (dpi). A remarkable increase in the activities of the total soluble phenolics (10-fold) and salicylic acid (16-fold) was detected 5 days after the treatment in foliar extracts of test plants relative to untreated control plants. The results showed that treatment of tomato plants with inactivated viral inoculum led to a significant enhancement of protection against Cucumber mosaic virus attack in a manner that mimics a real pathogen and induces systemic acquired resistance.

Experimental infections of Pacific oyster Crassostrea gigas using the Australian ostreid herpesvirus-1 (OsHV-1) µVar strain.

PubMed

Paul-Pont, Ika; Evans, Olivia; Dhand, Navneet K; Whittington, Richard J

2015-03-09

In Australia, the spread of the ostreid herpesvirus-1 microvariant (OsHV-1 µVar) threatens the Pacific oyster industry. There is an urgent need to develop an experimental infection model in order to study the pathogenesis of the virus under controlled laboratory conditions. The present study constitutes the first attempt to use archived frozen oysters as a source of inoculum, based on the Australian OsHV-1 µVar strain. Experiments were conducted to test (1) virus infectivity, (2) the dose-response relationship for OsHV-1, and (3) the best conditions in which to store infective viral inoculum. Intramuscular injection of a viral inoculum consistently led to an onset of mortality 48 h post-injection and a final cumulative mortality exceeding 90%, in association with high viral loads (1 × 105 to 3 × 107 copies of virus mg-1) in dead individuals. For the first time, an infective inoculum was produced from frozen oysters (tissues stored at -80°C for 6 mo). Storage of purified viral inoculum at +4°C for 3 mo provided similar results to use of fresh inoculum, whereas storage at -20°C, -80°C and room temperature was detrimental to infectivity. A dose-response relationship for OsHV-1 was identified but further research is recommended to determine the most appropriate viral concentration for development of infection models that would be used for different purposes. Overall, this work highlights the best practices and potential issues that may occur in the development of a reproducible and transferable infection model for studying the pathogenicity of the Australian OsHV-1 strain in Crassostrea gigas under experimental conditions.

Effects of pre-treatment technologies on dark fermentative biohydrogen production: A review.

PubMed

Bundhoo, M A Zumar; Mohee, Romeela; Hassan, M Ali

2015-07-01

Biohydrogen production from dark fermentation of lignocellulosic materials represents a huge potential in terms of renewable energy exploitation. However, the low hydrogen yield is currently hindering its development on industrial scale. This study reviewed various technologies that have been investigated for enhancing dark fermentative biohydrogen production. The pre-treatment technologies can be classified based on their applications as inoculum or substrates pre-treatment or they can be categorised into physical, chemical, physicochemical and biological based on the techniques used. From the different technologies reviewed, heat and acid pre-treatments are the most commonly studied technologies for both substrates and inoculum pre-treatment. Nevertheless, these two technologies need not necessarily be the most suitable since across different studies, a wide array of other emerging techniques as well as combined technologies have yielded positive findings. To date, there exists no perfect technology for either inoculum or substrate pre-treatment. Although the aim of inoculum pre-treatment is to suppress H2-consumers and enrich H2-producers, many sporulating H2-consumers survive the pre-treatment while some non-spore H2-producers are inhibited. Besides, several inoculum pre-treatment techniques are not effective in the long run and repeated pre-treatment may be required for continuous suppression of H2-consumers and sustained biohydrogen production. Furthermore, many technologies employed for substrates pre-treatment may yield inhibitory compounds that can eventually decrease biohydrogen production. Consequently, much research needs to be done to find out the best technology for both substrates and inoculum pre-treatment while also taking into consideration the energetic, economic and technical feasibility of implementing such a process on an industrial scale. Copyright © 2015 Elsevier Ltd. All rights reserved.

Ozone and infection of geranium flowers by Botrytis cinerea

DOE Office of Scientific and Technical Information (OSTI.GOV)

Manning, W.J.; Feder, W.A.; Perkins, I.

1970-01-01

Flowering plants of geranium cultivars were exposed to 0.2, 0.35, and 0.55 ppm ozone for 4-hr periods at 20/sup 0/C in a greenhouse fumigation chamber. Three fully-opened flower heads were sprayed with a spore suspension of Botrytis cinerea at 2000, 1000, or 500 spores/ml immediately before exposure to ozone began. Sterile distilled water was sprayed on noninoculated flower heads. All flowers were examined for evidence of infection 24 hr after the end of the ozone-exposure periods. All flower heads were then removed and placed in wet, loosely tied plastic bags and incubated at 20/sup 0/C for 72 hr, with examinationmore » at 24-hr intervals for evidence of infection. Ozone at 0.2 ppm did not injure the plants or prevent or inhibit flower infection by B. cinerea at all inoculum levels. Natural infection also occurred on some noninoculated flowers. Ozone at 0.35 ppm did not injure the plants or prevent infection, but did inhibit pathogenesis at the 500-spore/ml inoculum level and on noninoculated flowers. Ozone at 0.55 ppm caused moderate injury on all plants. Ozone at this level did not prevent infection, but did restrict pathogenesis on all inoculated and noninoculated flowers.« less

Laser cytometric analysis of FIV-induced injury in astroglia.

PubMed

Zenger, E; Collisson, E W; Barhoumi, R; Burghardt, R C; Danave, I R; Tiffany-Castiglioni, E

1995-02-01

Glia are the predominant brain cells infected by the lentiviruses human immunodeficiency virus (HIV) and feline immunodeficiency virus (FIV). The importance of astrocytes in maintenance of central nervous system homeostasis suggests that astrocytes are likely to play a strategic role in the progression of neurological disease in lentiviral-infected patients. In consideration of this postulate, the ability of FIV to cause injury by infection of cultured feline astroglia was examined via vital fluorescence assays. Intracellular Ca2+ homeostasis, plasma membrane permeability and fluidity, and cytosolic glutathione (GSH) levels were evaluated. Although basal intracellular Ca2+ was not significantly different between groups, FIV-infected astroglia displayed both a significant delay in development of peak Ca2+ levels following ionophore application and a decrease in the amount of Ca2+ released from intracellular stores. Plasma membrane lipid mobility was increased in FIV-infected cells within 24 h of infection. Glutathione levels were affected in a dose dependent fashion. With a standard viral inoculum there was a decrease in GSH which became significant after 8 days postinfection. With a high inoculum dose there was rapid loss of cell viability with an increase in GSH in surviving cells. We have identified several cellular processes altered in FIV-infected astroglia and our findings suggest that FIV-infection of feline astroglia affects cellular membranes, both structurally and functionally.

Actinobacteria consortium as an efficient biotechnological tool for mixed polluted soil reclamation: Experimental factorial design for bioremediation process optimization.

PubMed

Aparicio, Juan Daniel; Raimondo, Enzo Emanuel; Gil, Raúl Andrés; Benimeli, Claudia Susana; Polti, Marta Alejandra

2018-01-15

The objective of the present work was to establish optimal biological and physicochemical parameters in order to remove simultaneously lindane and Cr(VI) at high and/or low pollutants concentrations from the soil by an actinobacteria consortium formed by Streptomyces sp. M7, MC1, A5, and Amycolatopsis tucumanensis AB0. Also, the final aim was to treat real soils contaminated with Cr(VI) and/or lindane from the Northwest of Argentina employing the optimal biological and physicochemical conditions. In this sense, after determining the optimal inoculum concentration (2gkg -1 ), an experimental design model with four factors (temperature, moisture, initial concentration of Cr(VI) and lindane) was employed for predicting the system behavior during bioremediation process. According to response optimizer, the optimal moisture level was 30% for all bioremediation processes. However, the optimal temperature was different for each situation: for low initial concentrations of both pollutants, the optimal temperature was 25°C; for low initial concentrations of Cr(VI) and high initial concentrations of lindane, the optimal temperature was 30°C; and for high initial concentrations of Cr(VI), the optimal temperature was 35°C. In order to confirm the model adequacy and the validity of the optimization procedure, experiments were performed in six real contaminated soils samples. The defined actinobacteria consortium reduced the contaminants concentrations in five of the six samples, by working at laboratory scale and employing the optimal conditions obtained through the factorial design. Copyright © 2017 Elsevier B.V. All rights reserved.

Inoculum selection is crucial to ensure operational stability in anaerobic digestion.

PubMed

De Vrieze, Jo; Gildemyn, Sylvia; Vilchez-Vargas, Ramiro; Jáuregui, Ruy; Pieper, Dietmar H; Verstraete, Willy; Boon, Nico

2015-01-01

Anaerobic digestion is considered a key technology for the future bio-based economy. The microbial consortium carrying out the anaerobic digestion process is quite complex, and its exact role in terms of "elasticity", i.e., the ability to rapidly adapt to changing conditions, is still unknown. In this study, the role of the initial microbial community in terms of operational stability and stress tolerance was evaluated during a 175-day experiment. Five different inocula from stable industrial anaerobic digesters were fed a mixture of waste activated sludge and glycerol. Increasing ammonium pulses were applied to evaluate stability and stress tolerance. A different response in terms of start-up and ammonium tolerance was observed among the different inocula. Methanosaetaceae were the dominant acetoclastic methanogens, yet, Methanosarcinaceae increased in abundance at elevated ammonium concentrations. A shift from a Firmicutes to a Proteobacteria dominated bacterial community was observed in failing digesters. Methane production was strongly positively correlated with Methanosaetaceae, but also with Bacteria related to Anaerolinaceae, Clostridiales, and Alphaproteobacteria. Volatile fatty acids were strongly positively correlated with Betaproteobacteria and Bacteroidetes, yet ammonium concentration only with Bacteroidetes. Overall, these results indicate the importance of inoculum selection to ensure stable operation and stress tolerance in anaerobic digestion.

Environmentally Friendly Production of D(-) Lactic Acid by Sporolactobacillus nakayamae: Investigation of Fermentation Parameters and Fed-Batch Strategies.

PubMed

Michelz Beitel, Susan; Fontes Coelho, Luciana; Sass, Daiane Cristina; Contiero, Jonas

2017-01-01

The interest in the production of lactic acid has increased due to its wide range of applications. In the present study, the variables that affect fermentative D(-) lactic acid production were investigated: neutralizing agents, pH, temperature, inoculum percentage, agitation, and concentration of the medium components. An experimental design was applied to determine the optimal concentrations of the medium components and fermentation was studied using different feeding strategies. High production (122.41 g/L) and productivity (3.65 g/L·h) were efficiently achieved by Sporolactobacillus nakayamae in 54 h using a multipulse fed-batch technique with an initial medium containing 35 g/L of yeast extract (byproduct of alcohol production), 60 g/L of crystallized sugar, and 7.5 mL/L of salts. The fermentation process was conducted at 35°C and pH 6.0 controlled by NaOH with a 20% volume of inoculum and agitation at 125 rpm. The production of a high optically pure concentration of D(-) lactic acid combined with an environmentally friendly NaOH-based process demonstrates that S. nakayamae is a promising strain for D(-) lactic acid production.

Recycling food waste to clean water: the use of a biodigester's residual liquid inoculum (RLI) to decolourise textile azo dyes.

PubMed

Maganha de Almeida, A C; Backhaus, J; Corso, C R

2018-01-01

A residual liquid inoculum (RLI) was used to decolourise solutions of Acid Yellow 25 (AY25) and Direct Violet 51 (DV51) azo dyes. The RLI was obtained through anaerobic digestion of food waste from a university restaurant. The concentration of bacteria in the RLI was 8.45 × 10 7 CFU mL -1 . Dye solutions (50 μg mL -1 ) were inoculated with the RLI (20% v/v) and incubated at room temperature. The decolourisation studies took place at microaerophilic and in-batch conditions and at pH = 2.50. Initially, the dyes were taken up from solution by biosorption; maximum colour removal was achieved after 3 hours of incubation, with 88.66% for AY25 and 77.65% of DV51. At prolonged incubation times (3-96 hours) decolourisation was mainly attributed to biodegradation of the azo solutions, with breakage of the azo bond, as detected by UV-VIS spectroscopy and Fourier transform infrared (FT-IR) analysis. Analysis of UV-VIS absorption rates of dyes showed, however, that AY25 was more readily biodegradable whereas DV51 was more recalcitrant to the action of the RLI.

Anaerobic Decolorization and Detoxification of Cationic Red X-GRL by Shewanella oneidensis MR-1.

PubMed

Li, Qian; Feng, Xiao-Li; Li, Ting-Ting; Lu, Xue-Rong; Liu, Qiu-Yue; Han, Xue; Feng, Yu-Jie; Liu, Zhao-Ying; Zhang, Xi-Jia; Xiao, Xiang

2017-07-14

The ability of a electrochemically active bacterium, Shewanella oneidensis MR-1, to decolorize azo dye cationic red X-GRL (X-GRL) was investigated. S. oneidensis MR-1 showed a high decolorization capability for X-GRL under anaerobic conditions. The Mtr respiratory pathway was proved to be involved in the extracellular decolorization of X-GRL. The decolorization efficiency of S. oneidensis MR-1 was significantly inhibited when initial X-GRL concentration was over 200 mg L -1 . Increasing the inoculum volume of S. oneidensis MR-1 could obviously promote the X-GRL decolorization. The 100 mg L -1 X-GRL and 6% (v/v) inoculum volume were chosen as the optimal parameter. Under such a condition, almost all of X-GRL (100 mg L -1 ) could be completely reduced after 12-h incubation at the pH range of 5.5∼8.0 and temperature range of 30∼40 °C. Salinity in the medium also affected X-GRL decolorization. Lactate and citric acid were found to be the suitable electron donors for X-GRL decolorization. Although the genotoxicity increased slightly, the phytotoxicity of X-GRL in the decolorization process was significantly reduced by S. oneidensis MR-1.

Anaerobic biodegradability of Category 2 animal by-products: methane potential and inoculum source.

PubMed

Pozdniakova, Tatiana A; Costa, José C; Santos, Ricardo J; Alves, M M; Boaventura, Rui A R

2012-11-01

Category 2 animal by-products that need to be sterilized with steam pressure according Regulation (EC) 1774/2002 are studied. In this work, 2 sets of experiments were performed in mesophilic conditions: (i) biomethane potential determination testing 0.5%, 2.0% and 5.0% total solids (TS), using sludge from the anaerobic digester of a wastewater treatment plant as inoculum; (ii) biodegradability tests at a constant TS concentration of 2.0% and different inoculum sources (digested sludge from a wastewater treatment plant; granular sludge from an upflow anaerobic sludge blanket reactor; leachate from a municipal solid waste landfill; and sludge from the slaughterhouse wastewater treatment anaerobic lagoon) to select the more adapted inoculum to the substrate in study. The higher specific methane production was of 317 mL CH(4)g(-1) VS(substrate) for 2.0% TS. The digested sludge from the wastewater treatment plant led to the lowest lag-phase period and higher methane potential rate. Copyright © 2012 Elsevier Ltd. All rights reserved.

Inoculation of Pichia kudriavzevii RB1 degrades the organic acids present in raw compost material and accelerates composting.

PubMed

Nakasaki, Kiyohiko; Araya, Shogo; Mimoto, Hiroshi

2013-09-01

In this study, the yeast strain Pichia kudriavzevii RB1 was used as an inoculum to accelerate organic matter degradation of rabbit food with added organic acids, which was used as a model food waste for composting. The RB1 strain rapidly degraded the organic acids present in the raw compost material, leading to an increase in pH beyond the neutral level, within 2 days. Both mesophilic and thermophilic bacteria proliferated faster in the compost with RB1 inoculation than in that without inoculation. Although the yeast died with the increase in compost temperature, it affected the early stages of composting prior to the thermophilic stage and accelerated the composting process by 2 days by eliminating the initial lag phase seen in the growth of other microorganisms. Moreover, populations of Bacillus thermoamylovorans, Bacillus foraminis, and Bacillus coagulans became dominant during the thermophilic stages of both composting with and without RB1 inoculation. Copyright © 2013 Elsevier Ltd. All rights reserved.

Production of 6-pentyl-α-pyrone by trichoderma harzianum in solid-state fermentation

PubMed Central

de Souza Ramos, Aline; Fiaux, Sorele Batista; Leite, Selma Gomes Ferreira

2008-01-01

Many Trichoderma species are able to produce 6-pentyl-α-pyrone (6-PP), a lactone with coconut-like aroma. In the present work, several culture parameters were studied to enhance the production of 6-PP by Trichoderma harzianum 4040 in solid-state fermentation. Green coir powder added to a nutrient solution was used as support material for fermentation. A Plackett-Burman screening technique was applied, followed by a fractionary factorial design. The best culture conditions within the experimental domain studied were (100 g support)−1: sucrose, 3 g; NaNO3, 0.24 g; (NH4)2SO4, 0.18 g; KH2PO4, 0.1 g; inoculum concentration, 2.2 × 106 spores; moisture level, 55%. The temperature established was 28°C. The fermentation under the selected conditions led to a 6-PP production six times higher (5.0 mg/g dry matter) than the initial one (0.8 mg/g dry matter) after seven days of cultivation. PMID:24031295

Process performance of high-solids batch anaerobic digestion of sewage sludge.

PubMed

Liao, Xiaocong; Li, Huan; Cheng, Yingchao; Chen, Nan; Li, Chenchen; Yang, Yuning

2014-01-01

The characteristics of high-solids anaerobic digestion (AD) of sewage sludge were investigated by comparison with conventional low-solids processes. A series of batch experiments were conducted under mesophilic condition and the initial solid contents were controlled at four levels of 1.79%, 4.47%, 10.28% and 15.67%. During these experiments, biogas production, organic degradation and intermediate products were monitored. The results verified that high-solids batch AD of sewage sludge was feasible. Compared with the low-solids AD with solid contents of 1.79% or 4.47%, the high-solids processes decreased the specific biogas yield per gram of sludge volatile solids slightly, achieved the same organic degradation rate of about 40% within extended degradation time, but increased the volumetric biogas production rate and the treatment capability of digesters significantly. The blocked mass and energy transfer, the low substrate to inoculum rate and the excessive cumulative free ammonia were the main factors impacting the performance of high-solids batch AD.

Evaluation of indirect impedance for measuring microbial growth in complex food matrices.

PubMed

Johnson, N; Chang, Z; Bravo Almeida, C; Michel, M; Iversen, C; Callanan, M

2014-09-01

The suitability of indirect impedance to accurately measure microbial growth in real food matrices was investigated. A variety of semi-solid and liquid food products were inoculated with Bacillus cereus, Listeria monocytogenes, Staphylococcus aureus, Lactobacillus plantarum, Pseudomonas aeruginosa, Escherichia coli, Salmonella enteriditis, Candida tropicalis or Zygosaccharomyces rouxii and CO2 production was monitored using a conductimetric (Don Whitely R.A.B.I.T.) system. The majority (80%) of food and microbe combinations produced a detectable growth signal. The linearity of conductance responses in selected food products was investigated and a good correlation (R(2) ≥ 0.84) was observed between inoculum levels and times to detection. Specific growth rate estimations from the data were sufficiently accurate for predictive modeling in some cases. This initial evaluation of the suitability of indirect impedance to generate microbial growth data in complex food matrices indicates significant potential for the technology as an alternative to plating methods. Copyright © 2014 Elsevier Ltd. All rights reserved.

Production of 6-pentyl-α-pyrone by trichoderma harzianum in solid-state fermentation.

PubMed

de Souza Ramos, Aline; Fiaux, Sorele Batista; Leite, Selma Gomes Ferreira

2008-10-01

Many Trichoderma species are able to produce 6-pentyl-α-pyrone (6-PP), a lactone with coconut-like aroma. In the present work, several culture parameters were studied to enhance the production of 6-PP by Trichoderma harzianum 4040 in solid-state fermentation. Green coir powder added to a nutrient solution was used as support material for fermentation. A Plackett-Burman screening technique was applied, followed by a fractionary factorial design. The best culture conditions within the experimental domain studied were (100 g support)(-1): sucrose, 3 g; NaNO3, 0.24 g; (NH4)2SO4, 0.18 g; KH2PO4, 0.1 g; inoculum concentration, 2.2 × 10(6) spores; moisture level, 55%. The temperature established was 28°C. The fermentation under the selected conditions led to a 6-PP production six times higher (5.0 mg/g dry matter) than the initial one (0.8 mg/g dry matter) after seven days of cultivation.

Reduction of aflatoxins by Rhizopus oryzae and Trichoderma reesei.

PubMed

Hackbart, H C S; Machado, A R; Christ-Ribeiro, A; Prietto, L; Badiale-Furlong, E

2014-08-01

This study evaluated the ability of the microorganisms Rhizopus oryzae (CCT7560) and Trichoderma reesei (QM9414), producers of generally recognized as safe (GRAS) enzymes, to reduce the level of aflatoxins B1, B2, G1, G2, and M1. The variables considered to the screening were the initial number of spores in the inoculum and the culture time. The culture was conducted in contaminated 4 % potato dextrose agar (PDA) medium, and the residual mycotoxins were determined every 24 h by HPLC-FL. The fungus R. oryzae has reduced aflatoxins B1, B2, and G1 in the 96 h and aflatoxins M1 and G2 in the range of 120 h of culture by approximately 100 %. The fungus T. reesei has reduced aflatoxins B1, B2, and M1 in the 96 h and aflatoxin G1 in the range of 120 h of culture by approximately 100 %. The highest reduction occurred in the middle of R. oryzae culture.

Growth parameters of Penicillium expansum calculated from mixed inocula as an alternative to account for intraspecies variability.

PubMed

Garcia, Daiana; Ramos, Antonio J; Sanchis, Vicente; Marín, Sonia

2014-09-01

The aim of this work was to compare the radial growth rate (μ) and the lag time (λ) for growth of 25 isolates of Penicillium expansum at 1 and 20 ºC with those of the mixed inoculum of the 25 isolates. Moreover, the evolution of probability of growth through time was also compared for the single strains and mixed inoculum. Working with a mixed inoculum would require less work, time and consumables than if a range of single strains has to be used in order to represent a given species. Suitable predictive models developed for a given species should represent as much as possible the behavior of all strains belonging to this species. The results suggested, on one hand, that the predictions based on growth parameters calculated on the basis of mixed inocula may not accurately predict the behavior of all possible strains but may represent a percentage of them, and the median/mean values of μ and λ obtained by the 25 strains may be substituted by the value obtained with the mixed inoculum. Moreover, the predictions may be biased, in particular, the predictions of λ which may be underestimated (fail-safe). Moreover, the prediction of time for a given probability of growth through a mixed inoculum may not be accurate for all single inocula, but it may represent 92% and 60% of them at 20 and 1 ºC, respectively, and also their overall mean and median values. In conclusion, mixed inoculum could be a good alternative to estimate the mean or median values of high number of isolates, but not to account for those strains with marginal behavior. In particular, estimation of radial growth rate, and time for 0.10 and 0.50 probability of growth using a cocktail inoculum accounted for the estimates of most single isolates tested. For the particular case of probability models, this is an interesting result as for practical applications in the food industry the estimation of t10 or lower probability may be required. Copyright © 2014 Elsevier B.V. All rights reserved.

Inoculum Density Relationships for Infection of Some Eastern US Forest Species by Phytophthora ramorum

Treesearch

Paul Tooley; Marsha Browning; Robert Leighty

2013-01-01

Our objectives were to establish inoculum density relationships between P. ramorum and selected hosts using detached leaf and whole-plant inoculations. Young plants and detached leaves of Quercus prinus (Chestnut oak), Q. rubra (Northern red oak), Acer rubrum (red maple), ...

Severity of clinical disease and pathology in ferrets experimentally infected with influenza viruses is influenced by inoculum volume.

PubMed

Moore, Ian N; Lamirande, Elaine W; Paskel, Myeisha; Donahue, Danielle; Kenney, Heather; Qin, Jing; Subbarao, Kanta

2014-12-01

Ferrets are a valuable model for influenza virus pathogenesis, virus transmission, and antiviral therapy studies. However, the contributions of the volume of inoculum administered and the ferret's respiratory tract anatomy to disease outcome have not been explored. We noted variations in clinical disease outcomes and the volume of inoculum administered and investigated these differences by administering two influenza viruses (A/California/07/2009 [H1N1 pandemic] and A/Minnesota/11/2010 [H3N2 variant]) to ferrets intranasally at a dose of 10(6) 50% tissue culture infective doses in a range of inoculum volumes (0.2, 0.5, or 1.0 ml) and followed viral replication, clinical disease, and pathology over 6 days. Clinical illness and respiratory tract pathology were the most severe and most consistent when the viruses were administered in a volume of 1.0 ml. Using a modified micro-computed tomography imaging method and examining gross specimens, we found that the right main-stem bronchus was consistently larger in diameter than the left main-stem bronchus, though the latter was longer and straighter. These anatomic features likely influence the distribution of the inoculum in the lower respiratory tract. A 1.0-ml volume of inoculum is optimal for delivery of virus to the lower respiratory tract of ferrets, particularly when evaluation of clinical disease is desired. Furthermore, we highlight important anatomical features of the ferret lung that influence the kinetics of viral replication, clinical disease severity, and lung pathology. Ferrets are a valuable model for influenza virus pathogenesis, virus transmission, and antiviral therapy studies. Clinical disease in ferrets is an important parameter in evaluating the virulence of novel influenza viruses, and findings are extrapolated to virulence in humans. Therefore, it is highly desirable that the data from different laboratories be accurate and reproducible. We have found that, even when the same virus was administered at similar doses, different investigators reported a range of clinical disease outcomes, from asymptomatic infection to severe weight loss, ocular and nasal discharge, sneezing, and lethargy. We found that a wide range of inoculum volumes was used to experimentally infect ferrets, and we sought to determine whether the variations in disease outcome were the result of the volume of inoculum administered. These data highlight some less explored features of the model, methods of experimental infection, and clinical disease outcomes in a research setting. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Severity of Clinical Disease and Pathology in Ferrets Experimentally Infected with Influenza Viruses Is Influenced by Inoculum Volume

PubMed Central

Moore, Ian N.; Lamirande, Elaine W.; Paskel, Myeisha; Donahue, Danielle; Qin, Jing

2014-01-01

ABSTRACT Ferrets are a valuable model for influenza virus pathogenesis, virus transmission, and antiviral therapy studies. However, the contributions of the volume of inoculum administered and the ferret's respiratory tract anatomy to disease outcome have not been explored. We noted variations in clinical disease outcomes and the volume of inoculum administered and investigated these differences by administering two influenza viruses (A/California/07/2009 [H1N1 pandemic] and A/Minnesota/11/2010 [H3N2 variant]) to ferrets intranasally at a dose of 106 50% tissue culture infective doses in a range of inoculum volumes (0.2, 0.5, or 1.0 ml) and followed viral replication, clinical disease, and pathology over 6 days. Clinical illness and respiratory tract pathology were the most severe and most consistent when the viruses were administered in a volume of 1.0 ml. Using a modified micro-computed tomography imaging method and examining gross specimens, we found that the right main-stem bronchus was consistently larger in diameter than the left main-stem bronchus, though the latter was longer and straighter. These anatomic features likely influence the distribution of the inoculum in the lower respiratory tract. A 1.0-ml volume of inoculum is optimal for delivery of virus to the lower respiratory tract of ferrets, particularly when evaluation of clinical disease is desired. Furthermore, we highlight important anatomical features of the ferret lung that influence the kinetics of viral replication, clinical disease severity, and lung pathology. IMPORTANCE Ferrets are a valuable model for influenza virus pathogenesis, virus transmission, and antiviral therapy studies. Clinical disease in ferrets is an important parameter in evaluating the virulence of novel influenza viruses, and findings are extrapolated to virulence in humans. Therefore, it is highly desirable that the data from different laboratories be accurate and reproducible. We have found that, even when the same virus was administered at similar doses, different investigators reported a range of clinical disease outcomes, from asymptomatic infection to severe weight loss, ocular and nasal discharge, sneezing, and lethargy. We found that a wide range of inoculum volumes was used to experimentally infect ferrets, and we sought to determine whether the variations in disease outcome were the result of the volume of inoculum administered. These data highlight some less explored features of the model, methods of experimental infection, and clinical disease outcomes in a research setting. PMID:25187553

Influence of inoculum type, inorganic salt and nitrogen to carbon ratio on sclerotium formation and carotenoid production in surface culture of Penicillium sp. PT95.

PubMed

Han, Jian-Rong; Xu, Jun; Zhou, Xiao-Mei

2002-01-01

This study examined the respective effect of inoculum type, inorganic salt and nitrogen to carbon ratio on sclerotium formation and carotenoid production in surface culture of Penicillium sp. PT95. Neither the spore inoculum nor the mycelial pellet inoculum could result in the formation of sclerotium on a modified Czapek agar medium after incubation of 28 days, whereas the inoculum in the form of sclerotium caused the formation of numerous orange, sand-shaped sclerotia after incubation of 14 days. Among four inorganic salts tested, K(2)HPO(4) was more essential to the sclerotium formation and carotenoid production of strain PT95 as compared to KCl, MgSO(4) or FeSO(4). It was also shown that the combination of K(2)HPO(4), KCl and MgSO(4) could produce the best positive cooperation and give the highest sclerotia biomass (782 mg/plate) and carotenoid content in sclerotium (420 microg/g of dry sclerotia) as well as pigment yield (328 microg/plate). The medium containing 0.24 approximately 0.48 g/l sodium nitrate-nitrogen was effective to both the sclerotium formation and carotenoid production of strain PT95 when available maltose-carbon concentrations were at 5.26 approximately 21.05 g/l. The optimal N:C ratio was found to be 1:25.

Potential secondary inoculum sources of Botrytis cinerea and their influence on bunch rot development in dry Mediterranean climate vineyards.

PubMed

Calvo-Garrido, Carlos; Usall, Josep; Viñas, Inmaculada; Elmer, Philip Ag; Cases, Elena; Teixidó, Neus

2014-06-01

Epidemiological studies have described the life cycle of B. cinerea in vineyards. However, there is a lack of information on the several infection pathways and the quantitative relationships between secondary inoculum and bunch rot at harvest. Over two seasons, different spray programmes were used to determine key phenological stages for bunch rot development. Secondary inoculum sources within the bunch were also studied. The relative importance of flowering was evidenced in the given conditions, as treatments that included two fungicide applications at flowering were the most effective. In 2010, under conducive meteorological conditions for B. cinerea development after veraison, an extra application provided significantly higher control. Infections of necrotic tissues inside the bunch and latent infections developed mainly during flowering, while very low quantities of B. cinerea conidia were recovered from the fruit surface at veraison. Regression analysis correlated the incidence of latent infections and B. cinerea incidence on calyptras and aborted fruits at veraison with incidence of Botrytis bunch rot at harvest, presenting R2 = 0.95 for the overall regression model. This work points out key phenological stages during the season for bunch rot and B. cinerea secondary inoculum development and relates quantitatively inoculum sources at veraison to bunch rot at harvest. Recommendations for field applications of antibotrytic products are also suggested. © 2013 Society of Chemical Industry.

The effect of inoculum source and fluid shear force on the development of in vitro oral multispecies biofilms.

PubMed

Fernández, C E; Aspiras, M B; Dodds, M W; González-Cabezas, C; Rickard, A H

2017-03-01

Saliva has been previously used as an inoculum for in vitro oral biofilm studies. However, the microbial community profile of saliva is markedly different from hard- and soft-tissue-associated oral biofilms. Here, we investigated the changes in the biofilm architecture and microbial diversity of in vitro oral biofilms developed from saliva, tongue or plaque-derived inocula under different salivary shear forces. Four inoculum types (saliva, bacteria harvested from the tongue, toothbrush and curette-harvested plaque) were collected and pooled. Biofilms (n ≥ 15) were grown for 20 h in cell-free human saliva flowing at three different shear forces. Stained biofilms were imaged using a confocal laser scanning microscope. Biomass, thickness and roughness were determined by image analysis and bacterial community composition analysed using Ion Torrent. All developed biofilms showed a significant reduction in observed diversity compared with their respective original inoculum. Shear force altered biofilm architecture of saliva and curette-collected plaque and community composition of saliva, tongue and curette-harvested plaque. Different intraoral inocula served as precursors of in vitro oral polymicrobial biofilms which can be influenced by shear. Inoculum selection and shear force are key factors to consider when developing multispecies biofilms within in vitro models. © 2016 The Society for Applied Microbiology.

Effect of Inoculum and of Beta-Lactamase on the Anti-Staphylococcal Activity of Thirteen Penicillins and Cephalosporins

PubMed Central

Sabath, L. D.; Garner, Carol; Wilcox, Clare; Finland, Maxwell

1975-01-01

Because there are few persuasive data for selecting one semisynthetic penicillin or cephalosporin over another for treatment of serious staphylococcal infections, 118 recent clinical isolates of Staphylococcus aureus were studied to determine to what extent the presence of β-lactamase affected the relative anti-staphylococcal activity of six penicillins and seven cephalosporins. In addition, the effect of inoculum was studied for its possible effect on the anti-staphylococcal activity of the 13 β-lactam antibiotics. By all criteria, methicillin and nafcillin were clearly more resistant to both the inoculum effect and the production of staphylococcal β-lactamase, whereas benzylpenicillin and cephaloridine (especially benzyl-penicillin) were the most susceptible to these effects. Cephazolin was clearly more susceptible to staphylococcal β-lactamase and heavy inocula than the other cephalosporins (with the exception of cephaloridine), whereas cephalothin was the most resistant cephalosporin to these factors. The minimal inhibitory concentration for benzylpenicillin for tests with undiluted inoculum, compared to results with inoculum diluted 10−4, differed by a factor up to 16,384, whereas with methicillin and nafcillin the differences were rarely more than twofold. Ratios for the other 10 antibiotics fell between these extremes. These results suggest that methicillin or nafcillin is most stable to staphylococcal β-lactamase, and that benzylpenicillin and cephaloridine are the most susceptible. PMID:1167043

Susceptibility of Haemophilus influenzae to chloramphenicol and eight beta-lactam antibiotics.

PubMed Central

Thirumoorthi, M C; Kobos, D M; Dajani, A S

1981-01-01

We examined the minimal inhibitory concentrations and minimal bactericidal concentrations of chloramphenicol, ampicillin, ticarcillin, cefamandole, cefazolin, cefoxitin, cefotaxime, ceforanide, and moxalactam for 100 isolates of Haemophilus influenzae, 25 of which produced beta-lactamase. Susceptibility was not influenced by the capsular characteristic of the organism. The mean minimal inhibitory concentrations of cefamandole, ticarcillin, and ampicillin for beta-lactamase-producing strains were 3-, 120-, and 400-fold higher than their respective mean minimal inhibitory concentrations for beta-lactamase-negative strains. No such difference was noted for the other antibiotics. We performed time-kill curve studies, using chloramphenicol, ampicillin, cefamandole, cefotaxime, and moxalactam with two concentrations of the antimicrobial agents (4 or 20 times the minimal inhibitory concentrations) and two inoculum sizes (10(4) or 10(6) colony-forming units per ml). The inoculum size had no appreciable effect on the rate of killing of beta-lactamase-negative strains. The rates at which beta-lactamase-producing strains were killed by chloramphenicol, cefotaxime, and moxalactam was not influenced by the inoculum size. Whereas cefamandole in high concentrations was able to kill at 10(6) colony-forming units/ml of inoculum, it had only a temporary inhibiting effect at low drug concentrations. Methicillin and the beta-lactamase inhibitor CP-45,899 were able to neutralize the inactivation of cefamandole by a large inoculum of beta-lactamase-producing H. influenzae. PMID:6974541

Improving management of grape powdery mildew with new tools and knowledge

USDA-ARS?s Scientific Manuscript database

The assumption that inoculum of the grape powdery mildew pathogen is always available once conditions are suitable for inoculum release has been shown to be incorrect. Using various molecular techniques, we have shown that viticulturist can reduce their fungicide applications, on average, by 2.4 ap...

A test system to quantify inoculum in runoff from Phytophthora ramorum-infected plant roots

USDA-ARS?s Scientific Manuscript database

Foliar hosts of Phytophthora ramorum are often susceptible to root infection, but the epidemiological significance of such infections is unknown. We used a standardized test system to study inoculum in runoff from root-infected Viburnum tinus cuttings. Viburnum were inoculated by pouring a sporang...

Effects of microbial inoculum composition on rumen microbial ecology of dairy calves

USDA-ARS?s Scientific Manuscript database

The objective of this study was to determine if microbial inoculum composition affects dairy calf rumen microbial ecology. Holstein bull calves (n=20) were removed from their dam at birth and individually housed in calf hutches with sand bedding. Responses were studied using a randomized complete bl...

Interaction of rhizosphere bacteria, fertilizer, and vesicular-arbuscular mycorrhizal fungi with sea oats.

PubMed

Will, M E; Sylvia, D M

1990-07-01

Plants must be established quickly on replenished beaches in order to stabilize the sand and begin the dune-building process. The objective of this research was to determine whether inoculation of sea oats (Uniola paniculata L.) with bacteria (indigenous rhizosphere bacteria and N(2) fixers) alone or in combination with vesicular-arbuscular mycorrhizal fungi would enhance plant growth in beach sand. At two fertilizer-N levels, Klebsiella pneumoniae and two Azospirillum spp. did not provide the plants with fixed atmospheric N; however, K. pneumoniae increased root and shoot growth. When a sparingly soluble P source (CaHPO(4)) was added to two sands, K. pneumoniae increased plant growth in sand with a high P content. The phosphorus content of shoots was not affected by bacterial inoculation, indicating that a mechanism other than bacterially enhanced P availability to plants was responsible for the growth increases. When sea oats were inoculated with either K. pneumoniae or Acaligenes denitrificans and a mixed Glomus inoculum, there was no consistent evidence of a synergistic effect on plant growth. Nonetheless, bacterial inoculation increased root colonization by vesicular-arbuscular mycorrhizal fungi when the fungal inoculum consisted of colonized roots but had no effect on colonization when the inoculum consisted of spores alone. K. pneumoniae was found to increase spore germination and hyphal growth of Glomus deserticola compared with the control. The use of bacterial inoculants to enhance establishment of pioneer dune plants warrants further study.

The influence of inoculum composition on selected bioactive and nutritional parameters of grass pea tempeh obtained by mixed-culture fermentation with Rhizopus oligosporus and Aspergillus oryzae strains.

PubMed

Starzynska-Janiszewska, A; Stodolak, B; Dulinski, R; Mickowska, B

2012-04-01

Tempeh is a popular Indonesian product obtained from legume seeds by solid-state fermentation with Rhizopus sp. The aim of this research was to study the effect of simultaneous mixed-culture fermentation of grass pea seeds on selected parameters of products as compared to traditional tempeh. The inoculum contained different ratios of Rhizopus oligosporus and Aspergillus oryzae spores. The simultaneous fermentation of grass pea seeds with inoculum consisting of 1.2 × 10(6) R. oligosporus and 0.6 × 10(6) A. oryzae spores (per 60 g of seeds) resulted in a product of improved quality, as compared with traditionally made tempeh (obtained after inoculation with 1.2 × 10(6) R. oligosporus spores), at the same fermentation time. This product had radical scavenging ability 70% higher than the one obtained with pure R. oligosporus culture and contained 2.23 g/kg dm of soluble phenols. The thiamin and riboflavin levels were above three (340 µg/g dm) and two (50.50 µg/g dm) folds higher than in traditionally made tempeh, respectively. The product had 65% in vitro bioavailability of proteins and 33% in vitro bioavailability of sugars. It also contained 40% less 3-N-oxalyl-L-2, 3-diaminopropionic acid (0.074 g/kg dm), as compared to traditional tempeh.

Stochastic Assembly of Bacteria in Microwell Arrays Reveals the Importance of Confinement in Community Development

PubMed Central

Hansen, Ryan H.; Timm, Andrea C.; Timm, Collin M.; Bible, Amber N.; Morrell-Falvey, Jennifer L.; Pelletier, Dale A.; Simpson, Michael L.; Doktycz, Mitchel J.; Retterer, Scott T.

2016-01-01

The structure and function of microbial communities is deeply influenced by the physical and chemical architecture of the local microenvironment and the abundance of its community members. The complexity of this natural parameter space has made characterization of the key drivers of community development difficult. In order to facilitate these characterizations, we have developed a microwell platform designed to screen microbial growth and interactions across a wide variety of physical and initial conditions. Assembly of microbial communities into microwells was achieved using a novel biofabrication method that exploits well feature sizes for control of innoculum levels. Wells with incrementally smaller size features created populations with increasingly larger variations in inoculum levels. This allowed for reproducible growth measurement in large (20 μm diameter) wells, and screening for favorable growth conditions in small (5, 10 μm diameter) wells. We demonstrate the utility of this approach for screening and discovery using 5 μm wells to assemble P. aeruginosa colonies across a broad distribution of innoculum levels, and identify those conditions that promote the highest probability of survivial and growth under spatial confinement. Multi-member community assembly was also characterized to demonstrate the broad potential of this platform for studying the role of member abundance on microbial competition, mutualism and community succession. PMID:27152511

The impact of oxygen on the final alcohol content of wine fermented by a mixed starter culture.

PubMed

Morales, Pilar; Rojas, Virginia; Quirós, Manuel; Gonzalez, Ramon

2015-05-01

We have developed a wine fermentation procedure that takes advantage of the metabolic features of a previously characterized Metschnikowia pulcherrima strain in order to reduce ethanol production. It involves the use of M. pulcherrima/Saccharomyces cerevisiae mixed cultures, controlled oxygenation conditions during the first 48 h of fermentation, and anaerobic conditions thereafter. The influence of different oxygenation regimes and initial inoculum composition on yeast physiology and final ethanol content was studied. The impact of oxygenation on yeast physiology goes beyond the first aerated step and influences yields and survival rates during the anaerobic stage. The activity of M. pulcherrima in mixed oxygenated cultures resulted in a clear reduction in ethanol yield, as compared to S. cerevisiae. Despite relatively low initial cell numbers, S. cerevisiae always predominated in mixed cultures by the end of the fermentation process. Strain replacement was faster under low oxygenation levels. M. pulcherrima confers an additional advantage in terms of dissolved oxygen, which drops to zero after a few hours of culture, even under highly aerated conditions, and this holds true for mixed cultures. Alcohol reduction values about 3.7 % (v/v) were obtained for mixed cultures under high aeration, but they were associated to unacceptable volatile acidity levels. In contrast, under optimized conditions, only 0.35 g/L acetic acid was produced, for an alcohol reduction of 2.2 % (v/v), and almost null dissolved oxygen during the process.

Epidemiological Features and Trends of Brown Spot of Pear Disease Based on the Diversity of Pathogen Populations and Climate Change Effects.

PubMed

Moragrega, Concepció; Puig, Mireia; Ruz, Lídia; Montesinos, Emilio; Llorente, Isidre

2018-02-01

Brown spot of pear, caused by the fungus Stemphylium vesicarium, is an emerging disease of economic importance in several pear-growing areas in Europe. In recent years, new control strategies combining sanitation practices and fungicide applications according to developed forecasting models have been introduced to manage the disease. However, the pathogenic and saprophytic behavior of this pathogen makes it difficult to manage the disease. In addition, climate change can also result in variations in the severity and geographical distribution of the disease. In this study, ecological and epidemiological aspects of brown spot of pear disease related to inoculum characterization and climate change impact were elucidated. The pathogenic variation in S. vesicarium populations from pear orchards and its relationship to inoculum sources (air samples, leaf debris, and infected host and nonhost tissues) was determined using multivariate analysis. In total, six variables related to infection and disease development on cultivar Conference pear detached leaves of 110 S. vesicarium isolates were analyzed. A high proportion of isolates (42%) were nonpathogenic to pear; 85% of these nonpathogenic isolates were recovered from air samples. Most isolates recovered from lesions (93%) and pseudothecia (83%) were pathogenic to pear. A group of pathogenic isolates rapidly infected cultivar Conference pear leaves resulted in disease increase that followed a monomolecular model, whereas some S. vesicarium isolates required a period of time after inoculation to initiate infection and resulted in disease increase that followed a logistic model. The latter group was mainly composed of isolates recovered from pseudothecia on leaf debris, whereas the former group was mainly composed of isolates recovered from lesions on pear fruit and leaves. The relationship between the source of inoculum and pathogenic/aggressiveness profile was confirmed by principal component analysis. The effect of climate change on disease risk was analyzed in two pear-growing areas of Spain under two scenarios (A2 and B1) and for three periods (2005 to 2009, 2041 to 2060, and 2081 to 2100). Simulations showed that the level of risk predicted by BSPcast model increased to high or very high under the two scenarios and was differentially distributed in the two regions. This study is an example of how epidemiological models can be used to predict not only the onset of infections but also how climate change could affect brown spot of pear. [Formula: see text] Copyright © 2018 The Author(s). This is an open-access article distributed under the CC BY-NC-ND 4.0 International license .

Effect of prior vegetative growth, inoculum density and light on conidiation in Erysiphe necator

USDA-ARS?s Scientific Manuscript database

A driving force in epidemics of grape powdery mildew is the abundant production of conidia. Our objective was to better define the three factors involved in the qualitative change that occurs when a mildew colony switches from vegetative growth to sporulation –inoculum density, light, and a sporulat...

On-farm AM fungus inoculum production: a complete how-to on-farm am fungus inoculum production

USDA-ARS?s Scientific Manuscript database

Arbuscular mycorrhizal (AM) fungi are beneficial soil fungi that form a symbiosis with the majority of crop plants. The benefits to the plant include increased nutrient uptake and disease and drought resistance. This makes utilization of the symbiosis a potentially important part in ensuring the s...

Effects of inoculum density and wounding on stem infection of three Eastern U.S. forest species by Phytophthora ramorum

USDA-ARS?s Scientific Manuscript database

Seedlings of three Eastern US forest species (red maple, northern red oak, and chestnut oak) were inoculated by applying Phytophthora ramorum sporangia to stems at different inoculum densities with and without wounding. Disease occurred in all treatments involving wounds, and no disease was observe...

Effects of inoculum density and wounding on stem infection of three eastern US forest species by Phytophthora ramorum

Treesearch

P.W. Tooley; M. Browning; R.M. Leighty

2014-01-01

Seedlings of three Eastern US forest species Quercus rubra (northern red oak), Quercus prinus (chestnut oak) and Acer rubrum (red maple) were inoculated by applying Phytophthora ramorum sporangia to stems at different inoculum densities with and without wounding. Disease occurred in all...

Development of an assay for rapid detection and quantification of Verticillium dahliae in soil

USDA-ARS?s Scientific Manuscript database

Verticillium dahliae is responsible for Verticillium wilt on a wide range of hosts including strawberry, on which low inoculum densities can cause significant crop loss. Determination of inoculum density is currently done by soil plating, but this can take 6-8 weeks to complete and delay the grower...

Root susceptibility and inoculum production from roots of eastern oak species to Phytophthora ramorum

USDA-ARS?s Scientific Manuscript database

Little is known about root susceptibility of eastern tree species to Phytophthora ramorum. In this study, we examined root susceptibility and inoculum production from roots. Oak radicles of several eastern oak species were exposed to zoospore suspensions of 1, 10, 100, or 1000 zoospores per ml at ...

Seasonal availability of inoculum of the Heterobasidion root disease pathogen in central Wisconsin

Treesearch

Glen R. Stanosz; Denise R. Smith; Jennifer Juzwik

2016-01-01

After deposition of airborne basidiospores, the root disease pathogen Heterobasidion irregulare Garbelotto and Otrosina infects fresh conifer stumps and spreads through root grafts or by root contact to adjacent trees. Infection can be prevented, however, by borate application. Because the need for stump protection depends on inoculum availability...

Addition of Bacillus sp. inoculums in bedding for swine on a pilot scale: effect on microbial population and bedding temperature.

PubMed

Corrêa, E K; Ulguim, R R; Corrêa, L B; Castilhos, D D; Bianchi, I; Gil-Turnes, C; Lucia, T

2012-10-01

Thermal and microbiological characteristics of beddings for swine were compared according to their depth and of addition of inoculums. Bedding was added to boxes at 0.25 (25D) and 0.50 m (50D), with three treatments: control (no inoculums); T1, with 250 g of Bacillus cereus var. toyoii at 8.4 × 10(7) CFU; and T2, with 250 g of a pool of B. subtilis, Bacillus licheniformis and Bacillus polymyxa at 8.4 × 10(7) CFU (250 g for 25D and 500 g for 50D). Mean temperatures were 28.5 ± 3.9 at the surface and 35.2 ± 8.9 inside the beddings. The most probable number (MPN) of thermophilic bacteria was higher for T1 and T2 than for the control (P<0.05). The MPN of thermophilic bacteria and fungi was greater for D50 than for D25 (P<0.05). The use of 25D without inoculums is recommended due to the reduction of thermophilic microbiota. Copyright © 2012 Elsevier Ltd. All rights reserved.

Chemical characteristics of beddings for swine: effects of bedding depths and of addition of inoculums in a pilot-scale.

PubMed

Corrêa, E K; Corezzolla, J L; Corrêa, M N; Bianchi, I; Gil-Turnes, C; Lucia, T

2012-11-01

The effect of depths and of addition of inoculums on the chemical content of swine beddings was evaluated. For beddings 0.25m (25D) and 0.50m (50D) deep, three treatments were tested in two repeats with the same beddings: control (no inoculums); T1 (250g of Bacillus cereus var. toyoii at 8.4×10(7)CFU/g); and T2 (250g of a pool of Bacillus sp. at 8.4×10(7)CFU/g) (250g for 25D and 500g for 50D). For 25D, the C:N ratio was lower, but N, K and C contents were greater than for 50D (P<0.05). The inoculums did not benefit any chemical parameter (P>0.05). In the second repeat, beddings presented lower C:N ratio and greater N, P and K contents than in the first repeat (P<0.05). Thus, the compost produced after using 25D twice had greater fertilizer value than that of 50D. Copyright © 2012 Elsevier Ltd. All rights reserved.

Influence of inocula and grains on sclerotia biomass and carotenoid yield of Penicillium sp. PT95 during solid-state fermentation.

PubMed

Han, Jian-Rong; Yuan, Jing-Ming

2003-10-01

Various inocula and grains were evaluated for carotenoid production by solid-state fermentation using Penicillium sp. PT95. Millet medium was more effective in both sclerotia growth and carotenoid production than other grain media. An inoculum in the form of sclerotia yielded higher sclerotia biomass compared to either a spore inoculum or a mycelial pellet inoculum. Adding wheat bran to grain medium favored the formation of sclerotia. However, neither the inoculum type nor addition of wheat bran resulted in a significant change in the carotenoid content of sclerotia. Among grain media supplemented with wheat bran (wheat bran:grain =1:4 w/w, dry basis), a medium consisting of rice and wheat bran gave the highest sclerotia biomass (15.10 g/100 g grain), a medium consisting of buckwheat and wheat bran gave the highest content of carotenoid in sclerotia (0.826 mg/g dry sclerotia), and a medium consisting of millet and wheat bran gave the highest carotenoid yield (11.457 mg/100 g grain).

Rapid depletion of dissolved oxygen in 96-well microtiter plate Staphylococcus epidermidis biofilm assays promotes biofilm development and is influenced by inoculum cell concentration.

PubMed

Cotter, John J; O'Gara, James P; Casey, Eoin

2009-08-01

Biofilm-related research using 96-well microtiter plates involves static incubation of plates indiscriminate of environmental conditions, making oxygen availability an important variable which has not been considered to date. By directly measuring dissolved oxygen concentration over time we report here that dissolved oxygen is rapidly consumed in Staphylococcus epidermidis biofilm cultures grown in 96-well plates irrespective of the oxygen concentration in the gaseous environment in which the plates are incubated. These data indicate that depletion of dissolved oxygen during growth of bacterial biofilm cultures in 96-well plates may significantly influence biofilm production. Furthermore higher inoculum cell concentrations are associated with more rapid consumption of dissolved oxygen and higher levels of S. epidermidis biofilm production. Our data reveal that oxygen depletion during bacterial growth in 96-well plates may significantly influence biofilm production and should be considered in the interpretation of experimental data using this biofilm model.

Optimization of conditions for probiotic curd formulation by Enterococcus faecium MTCC 5695 with probiotic properties using response surface methodology.

PubMed

Ramakrishnan, Vrinda; Goveas, Louella Concepta; Prakash, Maya; Halami, Prakash M; Narayan, Bhaskar

2014-11-01

Enterococcus faecium MTCC 5695 possessing potential probiotic properties as well as enterocin producing ability was used as starter culture. Effect of time (12-24 h) and inoculum level (3-7 % v/v) on cell growth, bacteriocin production, antioxidant property, titrable acidity and pH of curd was studied by response surface methodology (RSM). The optimized conditions were 26.48 h and 2.17%v/v inoculum and the second order model validated. Co cultivation studies revealed that the formulated product had the ability to prevent growth of foodborne pathogens that affect keeping quality of the product during storage. The results indicated that application of E. faecium MTCC 5695 along with usage of optimized conditions attributed to the formation of highly consistent well set curd with bioactive and bioprotective properties. Formulated curd with potential probiotic attributes can be used as therapeutic agent for the treatment of foodborne diseases like Traveler's diarrhea and gastroenteritis which thereby help in improvement of bowel health.

The Ebb and Flow of Airborne Pathogens: Monitoring and Use in Disease Management Decisions.

PubMed

Mahaffee, Walter F; Stoll, Rob

2016-05-01

Perhaps the earliest form of monitoring the regional spread of plant disease was a group of growers gathering together at the market and discussing what they see in their crops. This type of reporting continues to this day through regional extension blogs, by crop consultants and more formal scouting of sentential plots in the IPM PIPE network (http://www.ipmpipe.org/). As our knowledge of plant disease epidemiology has increased, we have also increased our ability to detect and monitor the presence of pathogens and use this information to make management decisions in commercial production systems. The advent of phylogenetics, next-generation sequencing, and nucleic acid amplification technologies has allowed for development of sensitive and accurate assays for pathogen inoculum detection and quantification. The application of these tools is beginning to change how we manage diseases with airborne inoculum by allowing for the detection of pathogen movement instead of assuming it and by targeting management strategies to the early phases of the epidemic development when there is the greatest opportunity to reduce the rate of disease development. While there are numerous advantages to using data on inoculum presence to aid management decisions, there are limitations in what the data represent that are often unrecognized. In addition, our understanding of where and how to effectively monitor airborne inoculum is limited. There is a strong need to improve our knowledge of the mechanisms that influence inoculum dispersion across scales as particles move from leaf to leaf, and everything in between.

Effect of inoculum-substrate ratio on acclimatization of pharmaceutical effluent in an anaerobic batch reactor.

PubMed

Muruganandam, B; Saravanane, R; Lavanya, M; Sivacoumar, R

2008-07-01

Anaerobic treatment has gained tremendous success over the past two decades for treatment of industrial effluents. Over the past 30 years, the popularity of anaerobic wastewater treatment has increased as public utilities and industries have utilized its considerable benefits. Low biomass production, row nutrient requirements and the energy production in terms of methane yield are the significant advantages over aerobic treatment process. Due to the disadvantages reported in the earlier investigations, during the past decade, anaerobic biotechnology now seems to become a stable process technology in respect of generating a high quality effluent. The objective of the present experimental study was to compare the biodegradability of recalcitrant effluent (pharmaceutical effluent) for various inoculum-substrate ratios. The batch experiments were conducted over 6 months to get effect of ratio of inoculum-substrate on the acclimatization of pharmaceutical effluent. The tests were carried out in batch reactors, serum bottles, of volume 2000 mL and plastic canes of 10000 mL. Each inoculum was filled with a cow dung, sewage and phosphate buffer. The batch was made-up of diluted cow dung at various proportions of water and cow dung, i.e., 1:1 and 1:2 (one part of cow dung and one part of water by weight for 1:1). The bottles were incubated at ambient temperature (32 degrees C-35 degrees C). The bottles were closed tightly so that the anaerobic condition is maintained. The samples were collected and biodegradability was measured once in four days. The bottles were carefully stirred before gas measurement. The substrate was added to a mixture of inoculum and phosphate nutrients. The variations in pH, conductivity, alkalinity, COD, TS, TVS, VSS, and VFA were measured for batch process. The biogas productivity was calculated for various batches of inoculum-substrate addition and conclusions were drawn for expressing the biodegradability of pharmaceutical effluent on acclimatization period and influent COD concentration.

Influence of Inoculum Size and Marbofloxacin Plasma Exposure on the Amplification of Resistant Subpopulations of Klebsiella pneumoniae in a Rat Lung Infection Model▿

PubMed Central

Kesteman, Anne-Sylvie; Ferran, Aude A.; Perrin-Guyomard, Agnès; Laurentie, Michel; Sanders, Pascal; Toutain, Pierre-Louis; Bousquet-Mélou, Alain

2009-01-01

We tested the hypothesis that the bacterial load at the infection site could impact considerably on the pharmacokinetic/pharmacodynamic (PK/PD) parameters of fluoroquinolones. Using a rat lung infection model, we measured the influence of different marbofloxacin dosage regimens on selection of resistant bacteria after infection with a low (105 CFU) or a high (109 CFU) inoculum of Klebsiella pneumoniae. For daily fractionated doses of marbofloxacin, prevention of resistance occurred for an area-under-the-concentration-time-curve (AUC)/MIC ratio of 189 h for the low inoculum, whereas for the high inoculum, resistant-subpopulation enrichment occurred for AUC/MIC ratios up to 756 h. For the high-inoculum-infected rats, the AUC/MIC ratio, Cmax/MIC ratio, and time within the mutant selection window (TMSW) were not found to be effective predictors of resistance prevention upon comparison of fractionated and single administrations. An index corresponding to the ratio of the time that the drug concentrations were above the mutant prevention concentration (MPC) over the time that the drug concentrations were within the MSW (T>MPC/TMSW) was the best predictor of the emergence of resistance: a T>MPC/TMSW ratio of 0.54 was associated with prevention of resistance for both fractionated and single administrations. These results suggest that the enrichment of resistant bacteria depends heavily on the inoculum size at the start of an antimicrobial treatment and that classical PK/PD parameters cannot adequately describe the impact of different dosage regimens on enrichment of resistant bacteria. We propose an original index, the T>MPC/TMSW ratio, which reflects the ratio of the time that the less susceptible bacterial subpopulation is killed over the time that it is selected, as a potentially powerful indicator of prevention of enrichment of resistant bacteria. This ratio is valid only if plasma concentrations achieve the MPC. PMID:19738020

Effects of plant maturity and bacterial inoculum level on the colonization and internalization of escherichia coli 0157:H7 in growing spinach leaves.

USDA-ARS?s Scientific Manuscript database

The incidence of foodborne outbreaks linked to fresh produce has increased in the United States. Particularly noteworthy, was the 2006 Escherichia coli O157:H7 outbreak associated with pre-packaged baby spinach. The study aimed to determine whether E. coli O157:H7 would be present in the aerial leaf...

Prescreening slash pine and Cronartium pedigrees for evaluation of complementary gene action in fusiform rust disease.

Treesearch

H.E. Stelzer; Robert L. Doudrick; Thomas L. Kubisiak; C. Dana Nelson

1999-01-01

Single-urediniospore cultures of the fusiform rust fungus were used to inoculate seedlings from 10 full-sib families of a five-parent slash pine diallel at two different times in 1994. The presence or absence of fusiform rust galls was recorded for each inoculated seedling at 9 months postinoculation, and percent infection levels for each family-inoculum-time...

The Dermis as a Delivery Site of Trypanosoma brucei for Tsetse Flies

PubMed Central

Caljon, Guy; Van Reet, Nick; De Trez, Carl; Vermeersch, Marjorie; Pérez-Morga, David; Van Den Abbeele, Jan

2016-01-01

Tsetse flies are the sole vectors of Trypanosoma brucei parasites that cause sleeping sickness. Our knowledge on the early interface between the infective metacyclic forms and the mammalian host skin is currently highly limited. Glossina morsitans flies infected with fluorescently tagged T. brucei parasites were used in this study to initiate natural infections in mice. Metacyclic trypanosomes were found to be highly infectious through the intradermal route in sharp contrast with blood stream form trypanosomes. Parasite emigration from the dermal inoculation site resulted in detectable parasite levels in the draining lymph nodes within 18 hours and in the peripheral blood within 42 h. A subset of parasites remained and actively proliferated in the dermis. By initiating mixed infections with differentially labeled parasites, dermal parasites were unequivocally shown to arise from the initial inoculum and not from a re-invasion from the blood circulation. Scanning electron microscopy demonstrated intricate interactions of these skin-residing parasites with adipocytes in the connective tissue, entanglement by reticular fibers of the periadipocytic baskets and embedment between collagen bundles. Experimental transmission experiments combined with molecular parasite detection in blood fed flies provided evidence that dermal trypanosomes can be acquired from the inoculation site immediately after the initial transmission. High resolution thermographic imaging also revealed that intradermal parasite expansion induces elevated skin surface temperatures. Collectively, the dermis represents a delivery site of the highly infective metacyclic trypanosomes from which the host is systemically colonized and where a proliferative subpopulation remains that is physically constrained by intricate interactions with adipocytes and collagen fibrous structures. PMID:27441553

The potential for mycobiont sharing between shrubs and seedlings to facilitate tree establishment after wildfire at Alaska arctic treeline

Treesearch

Rebecca E. Hewitt; F. Stuart Chapin; Teresa N. Hollingsworth; D. Lee Taylor

2017-01-01

Root-associated fungi, particularly ectomycorrhizal fungi (EMF), are critical symbionts of all boreal tree species. Although climatically driven increases in wildfire frequency and extent have been hypothesized to increase vegetation transitions from tundra to boreal forest, fire reduces mycorrhizal inoculum. Therefore, changes in mycobiont inoculum may potentially...

Root susceptibility and inoculum production from roots of Eastern United States oak species to Phytophthora ramorum

USDA-ARS?s Scientific Manuscript database

Little is known about root susceptibility of eastern U.S. tree species to Phytophthora ramorum. In this study, we examined root susceptibility and inoculum production from roots. Sprouted acorns of Q. rubra, Q. palustrus, Q. coccinia, Q. alba, Q. michauxii and Q. prinus were exposed to motile zoos...

Effect of inoculum concentrations of Aspergillus flavus and A. parasiticus on aflatoxin accumulation and kernel infection in resistant and susceptible maize hybrids

USDA-ARS?s Scientific Manuscript database

Over a three year period, we compared aflatoxin accumulation and kernel infection in maize hybrids inoculated with six inoculum concentrations of Aspergillus flavus isolate NRRL 3357 or A. parasiticus isolate NRRL 6111 which is a norsolorinic acid producer. Aflatoxin resistant and susceptible mai...

New Strategy for a Suitable Fast Stabilization of the Biomethanization Performance

PubMed Central

Fernández-Güelfo, L. A.; Álvarez-Gallego, C. J.; Sales Márquez, D.; Romero García, L. I.

2012-01-01

The start-up strategies for thermophilic anaerobic reactors usually consist of an initial mesophilic stage (35°C), with an approximate duration of 185 days, and a subsequent thermophilic stage (55°C), which normally requires around 60 days to achieve the system stabilizatio. During the first 8–10 days of the mesophilic stage, the reactor is not fed so that the inoculum, which is generally a mesophilic anaerobic sludge, may be adapted to the organic solid waste. Between mesophilic and thermophilic conditions the reactor is still not fed in an effort to prevent possible imbalances in the proces. As a consequence, the start-up and stabilization of the biomethanization performance described in the literature require, at least, around 245 days. In this sense, a new strategy for the start-up and stabilization phases is presented in this study. This approach allows an important reduction in the overall time necessary for these stages in an anaerobic continuous stirred tank reactor (CSTR) operated at thermophilic-dry conditions for treating the organic fraction of the municipal solid waste (OFMSW): 60 days versus 245 days of conventional strategies. The new strategy uses modified SEBAC technology to adapt an inoculum to the OFMSW and the operational conditions prior to seeding the CSTR. PMID:23193374

Environmentally Friendly Production of D(−) Lactic Acid by Sporolactobacillus nakayamae: Investigation of Fermentation Parameters and Fed-Batch Strategies

PubMed Central

Michelz Beitel, Susan; Fontes Coelho, Luciana; Sass, Daiane Cristina

2017-01-01

The interest in the production of lactic acid has increased due to its wide range of applications. In the present study, the variables that affect fermentative D(−) lactic acid production were investigated: neutralizing agents, pH, temperature, inoculum percentage, agitation, and concentration of the medium components. An experimental design was applied to determine the optimal concentrations of the medium components and fermentation was studied using different feeding strategies. High production (122.41 g/L) and productivity (3.65 g/L·h) were efficiently achieved by Sporolactobacillus nakayamae in 54 h using a multipulse fed-batch technique with an initial medium containing 35 g/L of yeast extract (byproduct of alcohol production), 60 g/L of crystallized sugar, and 7.5 mL/L of salts. The fermentation process was conducted at 35°C and pH 6.0 controlled by NaOH with a 20% volume of inoculum and agitation at 125 rpm. The production of a high optically pure concentration of D(−) lactic acid combined with an environmentally friendly NaOH-based process demonstrates that S. nakayamae is a promising strain for D(−) lactic acid production. PMID:29081803

The combined effects of Dolichospermum flos-aquae, light, and temperature on microcystin production by Microcystis aeruginosa

NASA Astrophysics Data System (ADS)

Chen, Ruoqi; Li, Fangfang; Liu, Jiadong; Zheng, Hongye; Shen, Fei; Xue, Yarong; Liu, Changhong

2016-11-01

The effects of light, temperature, and coculture on the intracellular microcystin-LR (MC-LR) quota of Microcystis aeruginosa were evaluated based on coculture experiments with nontoxic Dolichospermum ( Anabaena) flos-aquae. The MC-LR quota and transcription of mcyB and mcyD genes encoding MC synthetases in M. aeruginosa were evaluated on the basis of cell counts, high-performance liquid chromatography, and reverse-transcription quantitative real-time PCR. The MC-LR quotas of M. aeruginosa in coculture with a 1/1 ratio of inoculum of the two species were significantly lower relative to monocultures 6-d after inoculation. Decreased MC-LR quotas under coculture conditions were enhanced by increasing the D. flos-aquae to M. aeruginosa ratio in the inoculum and by environmental factors, such as temperature and light intensity. Moreover, the transcriptional concentrations of mcyB and mcyD genes in M. aeruginosa were significantly inhibited by D. flos-aquae competition in coculture ( P <0.01), lowered to 20% of initial concentrations within 8 days. These data suggested that coculture eff ects by D. flos-aquae not only reduced M. aeruginosa's intracellular MC-LR quota via inhibition of genes encoding MC synthetases, but also that this eff ect was regulated by environmental factors, including temperature and light intensities.

Enhanced recovery of valuable metals from spent lithium-ion batteries through optimization of organic acids produced by Aspergillus niger.

PubMed

Bahaloo-Horeh, Nazanin; Mousavi, Seyyed Mohammad

2017-02-01

In the present study, spent medium bioleaching method was performed using organic acids produced by Aspergillus niger to dissolve Ni, Co, Mn, Li, Cu and Al from spent lithium-ion batteries (LIBs). Response surface methodology was used to investigate the effects and interactions between the effective factors of sucrose concentration, initial pH, and inoculum size to optimize organic acid production. Maximum citric acid, malic acid, and gluconic acid concentrations of 26,478, 1832.53 and 8433.76ppm, respectively, and a minimum oxalic acid concentration of 305.558ppm were obtained under optimal conditions of 116.90 (gl -1 ) sucrose concentration, 3.45% (vv -1 ) inoculum size, and a pH value of 5.44. Biogenically-produced organic acids are used for leaching of spent LIBs at different pulp densities. The highest metal recovery of 100% Cu, 100% Li, 77% Mn, and 75% Al occurred at 2% (wv -1 ) pulp density; 64% Co and 54% Ni recovery occurred at 1% (wv -1 ) pulp density. The bioleaching of metals from spent LIBs can decrease the environmental impact of this waste. The results of this study suggest that the process can be used for large scale industrial purposes. Copyright © 2016 Elsevier Ltd. All rights reserved.

Multi-Response Optimization of Granaticinic Acid Production by Endophytic Streptomyces thermoviolaceus NT1, Using Response Surface Methodology

PubMed Central

Roy, Sudipta; Halder, Suman Kumar; Banerjee, Debdulal

2016-01-01

Streptomyces thermoviolaceus NT1, an endophytic isolate, was studied for optimization of granaticinic acid production. It is an antimicrobial metabolite active against even drug resistant bacteria. Different media, optimum glucose concentration, initial media pH, incubation temperature, incubation period, and inoculum size were among the selected parameters optimized in the one-variable-at-a-time (OVAT) approach, where glucose concentration, pH, and temperature were found to play a critical role in antibiotic production by this strain. Finally, the Box–Behnken experimental design (BBD) was employed with three key factors (selected after OVAT studies) for response surface methodological (RSM) analysis of this optimization study.RSM analysis revealed a multifactorial combination; glucose 0.38%, pH 7.02, and temperature 36.53 °C as the optimum conditions for maximum antimicrobial yield. Experimental verification of model analysis led to 3.30-fold (61.35 mg/L as compared to 18.64 mg/L produced in un-optimized condition) enhanced granaticinic acid production in ISP2 medium with 5% inoculum and a suitable incubation period of 10 days. So, the conjugated optimization study for maximum antibiotic production from Streptomyces thermoviolaceus NT1 was found to result in significantly higher yield, which might be exploited in industrial applications. PMID:28952581

Sulfur oxidation to sulfate coupled with electron transfer to electrodes by Desulfuromonas strain TZ1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, T; Bain, TS; Barlett, MA

2014-01-02

Microbial oxidation of elemental sulfur with an electrode serving as the electron acceptor is of interest because this may play an important role in the recovery of electrons from sulfidic wastes and for current production in marine benthic microbial fuel cells. Enrichments initiated with a marine sediment inoculum, with elemental sulfur as the electron donor and a positively poised (+300 mV versus Ag/AgCl) anode as the electron acceptor, yielded an anode biofilm with a diversity of micro-organisms, including Thiobacillus, Sulfurimonas, Pseudomonas, Clostridium and Desulfuromonas species. Further enrichment of the anode biofilm inoculum in medium with elemental sulfur as the electronmore » donor and Fe(III) oxide as the electron acceptor, followed by isolation in solidified sulfur/Fe(III) medium yielded a strain of Desulfuromonas, designated strain TZ1. Strain TZ1 effectively oxidized elemental sulfur to sulfate with an anode serving as the sole electron acceptor, at rates faster than Desulfobulbus propionicus, the only other organism in pure culture previously shown to oxidize S with current production. The abundance of Desulfuromonas species enriched on the anodes of marine benthic fuel cells has previously been interpreted as acetate oxidation driving current production, but the results presented here suggest that sulfur-driven current production is a likely alternative.« less

Optimization of culturing condition and medium composition for the production of alginate lyase by a marine Vibrio sp. YKW-34

NASA Astrophysics Data System (ADS)

Fu, Xiaoting; Lin, Hong; Kim, Sang Moo

2008-02-01

Carbohydrases secreted by marine Vibrio sp. YKW-34 with strong Laminaria cell wall degrading ability were screened, and among them alginate lyase was found to be dominant. The effects of medium composition and culturing condition on the production of alginate lyase by marine Vibrio sp. YKW-34 in flask were investigated in this study. In the culture medium of marine broth, no alginate lyase was produced. The activity of the alginate lyase, after being induced, reached 5 UmL-1. The best inoculum volume and inoculum age were 10% and 12 h, respectively. The optimal temperature for alginate lyase production was 25°C. The fermentation medium was composed of 0.5% of Laminaria powder and 0.2% of KNO3 with an initial acidity of pH 8.0. Alginate could induce alginate lyase production but not as efficiently as Laminaria powder did. The addition of fucoidan, cellulose and glucose had negative effect on the alginate lyase production. Other kinds of nitrogen sources, such as yeast extract, beef extract and peptone, had positive effect on the growth of the microorganism and negative effect on alginate lyase production. In addition, the time course of alginate lyase production under the optimized condition was described. The optimal harvest time was 48 h.

Influence of feed/inoculum ratios and waste cooking oil content on the mesophilic anaerobic digestion of food waste.

PubMed

Li, Yangyang; Jin, Yiying; Borrion, Aiduan; Li, Jinhui

2018-03-01

Information on the anaerobic digestion (AD) of food waste (FW) with different waste cooking oil contents is limited in terms of the effect of the initial substrate concentrations. In this work, batch tests were performed to evaluate the combined effects of waste cooking oil content (33-53%) and feed/inoculum (F/I) ratios (0.5-1.2) on biogas/methane yield, process stability parameters and organics reduction during the FW AD. Both waste cooking oil and the inoculation ratios were found to affect digestion parameters during the AD process start-up and the F/I ratio was the predominant factor affecting AD after the start-up phase. The possible inhibition due to acidification caused by volatile fatty acids accumulation, low pH values and long-chain fatty acids was reversible. The characteristics of the final digestate indicated a stable anaerobic system, whereas samples with F/I ratios ranging from 0.8 to 1.2 display higher propionic and valeric acid contents and high amounts of total ammonia nitrogen and free ammonia nitrogen. Overall, F/I ratios higher than 0.70 caused inhibition and resulted in low biogas/methane yields from the FW. Copyright © 2018 Elsevier Ltd. All rights reserved.

Lactic acid fermentation of human urine to improve its fertilizing value and reduce odour emissions.

PubMed

Andreev, N; Ronteltap, M; Boincean, B; Wernli, M; Zubcov, E; Bagrin, N; Borodin, N; Lens, P N L

2017-08-01

During storage of urine, urea is biologically decomposed to ammonia, which can be lost through volatilization and in turn causes significant unpleasant smell. In response, lactic acid fermentation of urine is a cost-effective technique to decrease nitrogen volatilization and reduce odour emissions. Fresh urine (pH = 5.2-5.3 and NH 4 + -N = 1.2-1.3 g L -1 ) was lacto-fermented for 36 days in closed glass jars with a lactic acid bacterial inoculum from sauerkraut juice and compared to untreated, stored urine. In the lacto-fermented urine, the pH was reduced to 3.8-4.7 and the ammonium content by 22-30%, while the pH of the untreated urine rose to 6.1 and its ammonium content increased by 32% due to urea hydrolysis. The concentration of lactic acid bacteria in lacto-fermented urine was 7.3 CFU ml -1 , suggesting that urine is a suitable growth medium for lactic acid bacteria. The odour of the stored urine was subjectively perceived by four people to be twice as strong as that of lacto-fermented samples. Lacto-fermented urine induced increased radish germination compared to stored urine (74-86% versus 2-31%). Adding a lactic acid bacterial inoculum to one week old urine in the storage tanks in a urine-diverting dry toilet reduced the pH from 8.9 to 7.7 after one month, while the ammonium content increased by 35%, probably due to the high initial pH of the urine. Given that the hydrolyzed stale urine has a high buffering capacity, the lactic acid bacterial inoculum should be added to the urine storage tank of a UDDT before urine starts to accumulate there to increase the efficiency of the lactic acid fermentation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Restoring the biological crust cover of soils across biomes in arid North America

NASA Astrophysics Data System (ADS)

Garcia-Pichel, Ferran; Antoninka, Anita; Bowker, Matthew; Giraldo Silva, Ana; Nelson, Corey; Velasco Ayuso, Sergio; Barger, Nichole; Belnap, Jayne; Reed, Sasha; Duniway, Michael

2015-04-01

Biological soil crust communities provide important ecosystem services to arid lands, particularly regarding soil fertility and stability against erosion. In North America, and in many other areas of the globe, increasingly intense human activities, ranging from cattle grazing to military training, have resulted in the significant deterioration of biological soil surface cover of soils. With the intent of attaining sustainable land use practices, we are conducting a 5-year, multi-institutional research effort to develop feasible soil crusts restoration strategies for US military lands. We are including field sites of varying climatic regions (warm and cold deserts, in the Chihuahuan Desert and in the Great Basin, respectively) and varying edaphic characteristics (sandy and silty soils in each). We have multiple aims. First, we aim to establishing effective "biocrust nurseries" that produce viable and pedigreed inoculum, as a supply center for biocrust restoration and for research and development. Second, we aim to develop optimal field application methods of biocrust inoculum in a series of field trials. Currently in our second year of research, we will be reporting on significant advances made on optimizing methodologies for the large-scale supply of inoculum based on a) pedigreed laboratory cultures that match the microbial community structure of the original sites, and b) "in soil" biomass enhancement, whereby small amounts of local crusts are nursed under greenhouse conditions to yield hundred-fold increases in biomass without altering significantly community structure. We will also report on field trials for methodologies in field application, which included shading, watering, application of chemical polymers, and soil surface roughening. In a soon-to-be-initiated effort we also aim to evaluate soil and plant responses to biocrust restoration with respect to plant community structure, soil fertility, and soil stability, in multi-factorial field experiments. An important part of the plan will be to construct effective channels for sharing challenges and solutions in biocrust restoration with military and federal land managers.

Batch, design optimization, and DNA sequencing study for continuous 1,3-propanediol production from waste glycerol by a soil-based inoculum.

PubMed

Kanjilal, Baishali; Noshadi, Iman; Bautista, Eddy J; Srivastava, Ranjan; Parnas, Richard S

2015-03-01

1,3-propanediol (1,3-PD) was produced with a robust fermentation process using waste glycerol feedstock from biodiesel production and a soil-based bacterial inoculum. An iterative inoculation method was developed to achieve independence from soil and selectively breed bacterial populations capable of glycerol metabolism to 1,3-PD. The inoculum showed high resistance to impurities in the feedstock. 1,3-PD selectivity and yield in batch fermentations was optimized by appropriate nutrient compositions and pH control. The batch yield of 1,3-PD was maximized to ~0.7 mol/mol for industrial glycerol which was higher than that for pure glycerin. 16S rDNA sequencing results show a systematic selective enrichment of 1,3-PD producing bacteria with iterative inoculation and subsequent process control. A statistical design of experiments was carried out on industrial glycerol batches to optimize conditions, which were used to run two continuous flow stirred-tank reactor (CSTR) experiments over a period of >500 h each. A detailed analysis of steady states at three dilution rates is presented. Enhanced specific 1,3-PD productivity was observed with faster dilution rates due to lower levels of solvent degeneration. 1,3-PD productivity, specific productivity, and yield of 1.1 g/l hr, 1.5 g/g hr, and 0.6 mol/mol of glycerol were obtained at a dilution rate of 0.1 h(-1)which is bettered only by pure strains in pure glycerin feeds.

Dry anaerobic digestion of high solids content dairy manure at high organic loading rates in psychrophilic sequence batch reactor.

PubMed

Massé, Daniel I; Saady, Noori M Cata

2015-05-01

Cow manure with bedding is renewable organic biomass available around the year on dairy farms. Developing efficient and cost-effective psychrophilic dry anaerobic digestion (PDAD) processes could contribute to solving farm-related environmental, energy, and manure management problems in cold-climate regions. This study was to increase the organic loading rate (OLR), fed to a novel psychrophilic (20 °C) dry anaerobic digestion of 27% total solid dairy manure (cow feces and wheat straw) in sequence batch reactor (PDAD-SBR), by 133 to 160%. The PDAD-SBR process operated at treatment cycle length of 21 days and OLR of 7.0 and 8.0 g total chemical oxygen demand (TCOD) kg(-1) inoculum day(-1) (5.2 ± 0.1 and 5.8 ± 0.0 g volatile solids (VS) kg(-1) inoculum day(-1)) for four successive cycles (84 days) produced average specific methane yields (SMYs) of 147.1 ± 17.2 and 143.2 ± 11.7 normalized liters (NL) CH4 kg(-1) VS fed, respectively. PDAD of cow feces and wheat straw is possible with VS-based inoculum-to-substrate ratio of 1.45 at OLR of 8.0 g TCOD kg(-1) inoculum day(-1). Hydrolysis was the limiting step reaction. The VS removal averaged around 57.4 ± 0.5 and 60.5 ± 5.7% at OLR 7.0 and 8.0 g TCOD kg(-1) inoculum day(-1), respectively.

Anaerobic Digestion Performance in the Energy Recovery of Kiwi Residues

NASA Astrophysics Data System (ADS)

Martins, Ramiro; Boaventura, Rui; Paulista, Larissa

2017-12-01

World production and trade of fruits generate losses in the harvest, post-harvest, handling, distribution and consumption phases, corresponding to 6.8% of total production. These residues present high potential as a substrate for the anaerobic digestion process and biogas generation. Thus, the energy valuation of the agro-industrial residues of kiwi production was evaluated by anaerobic digestion, aiming at optimizing the biogas production and its quality. Ten assays were carried out in a batch reactor (500 mL) under mesophilic conditions and varying a number of operational factors: different substrate/inoculum ratios; four distinct values for C: N ratio; inoculum from different digesters; and inoculum collected at different times of the year. The following parameters were used to control and monitor the process: pH, alkalinity, volatile fatty acids (VFA), volatile solids (VS) and chemical oxygen demand (COD). Among the tests performed, the best result obtained for the biogas production corresponded to the use of 2 g of substrate and 98 mL of inoculum of the anaerobic digester of the Wastewater Treatment Plant (WWTP) of Bragança, with addition of 150 mg of bicarbonate leading to a production of 1628 L biogas.kg-1 VS (57% methane). In relation to the biogas quality, the best result was obtained with 20 g of substrate and 380 mL of inoculum from the anaerobic digester sludge of WWTP of Ave (with addition 600 mg of sodium bicarbonate), presenting a value of 85% of CH4, with a production of 464 L biogas.kg-1 VS.

Reactor performances and microbial communities of biogas reactors: effects of inoculum sources.

PubMed

Han, Sheng; Liu, Yafeng; Zhang, Shicheng; Luo, Gang

2016-01-01

Anaerobic digestion is a very complex process that is mediated by various microorganisms, and the understanding of the microbial community assembly and its corresponding function is critical in order to better control the anaerobic process. The present study investigated the effect of different inocula on the microbial community assembly in biogas reactors treating cellulose with various inocula, and three parallel biogas reactors with the same inoculum were also operated in order to reveal the reproducibility of both microbial communities and functions of the biogas reactors. The results showed that the biogas production, volatile fatty acid (VFA) concentrations, and pH were different for the biogas reactors with different inocula, and different steady-state microbial community patterns were also obtained in different biogas reactors as reflected by Bray-Curtis similarity matrices and taxonomic classification. It indicated that inoculum played an important role in shaping the microbial communities of biogas reactor in the present study, and the microbial community assembly in biogas reactor did not follow the niche-based ecology theory. Furthermore, it was found that the microbial communities and reactor performances of parallel biogas reactors with the same inoculum were different, which could be explained by the neutral-based ecology theory and stochastic factors should played important roles in the microbial community assembly in the biogas reactors. The Bray-Curtis similarity matrices analysis suggested that inoculum affected more on the microbial community assembly compared to stochastic factors, since the samples with different inocula had lower similarity (10-20 %) compared to the samples from the parallel biogas reactors (30 %).

Bacterial Growth in Tray Pack Acidified Rice

DTIC Science & Technology

1987-01-01

Bacillus coagulans , which were able to survive the pasteurization processing temperature. Because of the potential for spoilage that was indicated...Inoculum A miKed inoculum consisting o-f Bacillus sphaericus, Bacillus circulans and iour strains of Bacillus coagulans was prepared. All cultures...ineffective in preventing growth of sporeforming bacillus species. Moreover, there was nonuniform distribution of the acidulant, which resulted in

Extrapolation of a predictive model for growth of a low inoculum size of Salmonella typhimurium DT104 on chicken skin to higher inoculum sizes

USDA-ARS?s Scientific Manuscript database

Validation of model predictions for independent variables not included in model development can save time and money by identifying conditions for which new models are not needed. A single strain of Salmonella Typhimurium DT104 was used to develop a general regression neural network model for growth...

Key Factors Controlling the Growth of Biological Soil Crusts: Towards a Protocol to Produce Biocrusts in Greenhouse Facilities

NASA Astrophysics Data System (ADS)

Velasco Ayuso, Sergio; María Giraldo Silva, Ana; Nelson, Corey; Barger, Nichole; Antoninka, Anita; Bowker, Matthew; Garcia-Pichel, Ferran

2016-04-01

Biological soil crusts (= biocrusts) are topsoil communities comprise of, but not limited to, cyanobacteria, algae, lichens, and mosses that grow intimately associated with soil particles in drylands. Biocrusts have central ecological roles in these areas as sources of carbon and nutrients, and efficiently retain water and prevent soil erosion, which improves soil structure and promotes soil fertility. However, human activities, such as cattle grazing, hiking or military training, are rapidly striking biocrusts. Although it is well known that the inoculation with cyanobacteria or lichens can enhance the recovery of biocrusts in degraded soils, little is known about the factors that control their growth rates. Using soil and inocula from four different sites located in one cold desert (Utah) and in one hot desert (New Mexico), we performed a fractional factorial experiment involving seven factors (water, light, P, N, calcium carbonate, trace metals and type of inoculum) to screen their effects on the growth of biocrusts. After four months, we measured the concentration of chlorophyll a, and we discovered that water, light and P, N or P+N were the most important factors controlling the growth of biocrusts. In the experimental treatments involving these three factors we measured a similar concentration of chlorophyll a (or even higher) to this found in the field locations. Amplification of the 16S rRNA gene segment using universal bacteria primers revealed a microbial community composition in the biocrusts grown that closely corresponds to initial measurements made on inocula. In summary, based on our success in obtaining biocrust biomass from natural communities in greenhouse facilities, without significantly changing its community composition at the phylum and cyanobacterial level, we are paving the road to propose a protocol to produce a high quality-nursed inoculum aiming to assist restoration of arid and semi-arid ecosystems affected by large-scale disturbances.

Optimization of exopolysaccharide production from Pseudomonas stutzeri AS22 and examination of its metal-binding abilities.

PubMed

Maalej, H; Hmidet, N; Boisset, C; Buon, L; Heyraud, A; Nasri, M

2015-02-01

To investigate the effect of culture conditions and medium components on exopolysaccharide (EPS) production by Pseudomonas stutzeri AS22 and to access the EPS performance as a metal-binding exopolysaccharide. The EPS production conditions of Ps. stutzeri AS22 in submerged culture were optimized using two approaches for EPS quantification, and its metal-binding capacity was evaluated using both single and mixed metal ions systems. Maximum EPS level was achieved after 24 h of incubation at 30°C with an initial pH of 8.0, 250 rev min(-1) stirring level and 10% inoculum size. 50 g l(-1) starch, 5 g l(-1) yeast extract, 0.5 g l(-1) NaCl, 1.4 g l(-1) K2 HPO4, 0.4 g l(-1) MgSO4, 0.4 g l(-1) CaCl2 and 1 g l(-1) mannose were found to be the most suitable carbon, nitrogen, mineral and additional carbohydrate sources, respectively. From metal-binding experiments, the crude EPS showed interesting metal adsorption capacity adopting the order Pb > Co > Fe > Cu > Cd. Lead was preferentially biosorbed with a maximal uptake of 460 mg g(-1) crude EPS. Under the optimal culture requirements, EPS level reached 10.2 g l(-1) after 24 h of fermentation, seven times more than the production under initial conditions. According to the metal-binding assay, the crude EPS has potential to be used as a novel biosorbent in the treatment of heavy metals-contaminated water. Our results are interesting in terms of yield as well as efficiency for the potential use of the Ps. stutzeri exopolysaccharide as a metal-absorbent polymer in the bioremediation field. © 2014 The Society for Applied Microbiology.

Disease on nursery stock as affected by environmental factors and seasonal inoculum levels of Phytophthora ramorum in stream water used for irrigation

Treesearch

S.A. Tjosvold; D.L. Chambers; S.T. Koike; S.R. Mori

2008-01-01

A pear bait monitoring system was used to detect and quantify Phytophthora ramorum propagules in streams that flow through woodland areas with sudden oak death in Santa Cruz County, CA from 2001 to 2007. Stream propagules were detected most frequently or occurred in highest concentrations in winter and spring. The stream propagule concentration was...

Inoculum reduction measures to manage Armillaria root disease in a severely infected stand of ponderosa pine in south-central Washington: 35-year results

Treesearch

Charles G. Shaw; D.W. Omdal; A. Ramsey-Kroll; L.F. Roth

2012-01-01

A stand of ponderosa pine (Pinus ponderosa) severely affected by Armillaria root disease was treated with five different levels of sanitation by root removal to reduce root disease losses in the regenerating stand. Treatments included the following: (1) all trees pushed over by machine, maximum removal of roots by machine ripping, and visible...

Evaluation of various parameters of calcium-alginate immobilization method for enhanced alkaline protease production by Bacillus licheniformis NCIM-2042 using statistical methods.

PubMed

Potumarthi, Ravichandra; Subhakar, Ch; Pavani, A; Jetty, Annapurna

2008-04-01

Calcium-alginate immobilization method for the production of alkaline protease by Bacillus licheniformis NCIM-2042 was optimized statistically. Four variables, such as sodium-alginate concentration, calcium chloride concentration, inoculum size and agitation speed were optimized by 2(4) full factorial central composite design and subsequent analysis and model validation by a second-order regression equation. Eleven carbon, 11 organic nitrogen and seven inorganic nitrogen sources were screened by two-level Plackett-Burman design for maximum alkaline protease production by using optimized immobilized conditions. The levels of four variables, such as Na-alginate 2.78%; CaCl(2), 2.15%; inoculum size, 8.10% and agitation, 139 rpm were found to be optimum for maximal production of protease. Glucose, soybean meal and ammonium sulfate were resulted in maximum protease production at 644 U/ml, 720 U/ml, and 806 U/ml when screened for carbon, organic nitrogen and inorganic nitrogen sources, respectively, using optimized immobilization conditions. Repeated fed batch mode of operation, using optimized immobilized conditions, resulted in continuous operation for 12 cycles without disintegration of beads. Cross-sectional scanning electron microscope images have shown the growth pattern of B. licheniformis in Ca-alginate immobilized beads.

Evaluation of cotton stalk hydrolysate for xylitol production.

PubMed

Sapcı, Burcu; Akpinar, Ozlem; Bolukbasi, Ufuk; Yilmaz, Levent

2016-07-03

Cotton stalk is a widely distributed and abundant lignocellulosic waste found in Turkey. Because of its rich xylose content, it can be a promising source for the production of xylitol. Xylitol can be produced by chemical or biotechnological methods. Because the biotechnological method is a simple process with great substrate specificity and low energy requirements, it is more of an economic alternative for the xylitol production. This study aimed to use cotton stalk for the production of xylitol with Candida tropicalis Kuen 1022. For this purpose, the combined effects of different oxygen concentration, inoculum level and substrate concentration were investigated to obtain high xylitol yield and volumetric xylitol production rate. Candida tropicalis Kuen 1022 afforded different concentrations of xylitol depending on xylose concentration, inoculum level, and oxygen concentration. The optimum xylose, yeast concentration, and airflow rate for cotton stalk hydrolysate were found as 10.41 g L(-1), 0.99 g L(-1), and 1.02 vvm, respectively, and under these conditions, xylitol yield and volumetric xylitol production rate were obtained as 36% and 0.06 g L(-1) hr(-1), respectively. The results of this study show that cotton stalk can serve as a potential renewable source for the production of xylitol.

Use of wood vinegar to enhance 5-aminolevulinic acid production by selected Rhodopseudomonas palustris in rubber sheet wastewater for agricultural use.

PubMed

Nunkaew, Tomorn; Kantachote, Duangporn; Chaiprapat, Sumate; Nitoda, Teruhiko; Kanzaki, Hiroshi

2018-05-01

This study aimed to produce inexpensive 5-aminolevulinic acid (ALA) in a non-sterile latex rubber sheet wastewater (RSW) by Rhodopseudomonas palustris TN114 and PP803 for the possibility to use in agricultural purposes by investigating the optimum conditions, and applying of wood vinegar (WV) as an economical source of levulinic acid to enhance ALA content. The Box-Behnken Design experiment was conducted under microaerobic-light conditions for 96 h with TN114, PP803 and their mixed culture (1:1) by varying initial pH, inoculum size (% v/v) and initial chemical oxygen demand (COD, mg/L). Results showed that the optimal condition (pH, % inoculum size, COD) of each set to produce extracellular ALA was found at 7.50, 6.00, 2000 for TN114; 7.50, 7.00, 3000 for PP803; and 7.50, 6.00, 4000 for a mixed culture; and each set achieved COD reduction as high as 63%, 71% and 75%, respectively. Addition of the optimal concentration of WV at mid log phase at 0.63% for TN114, and 1.25% for PP803 and the mixed culture significantly increased the ALA content by 3.7-4.2 times (128, 90 and 131 μM, respectively) compared to their controls. ALA production cost could be reduced approximately 31 times with WV on the basis of the amount of levulinic acid used. Effluent containing ALA for using in agriculture could be achieved by treating the RSW with the selected ALA producer R. palustris strains under the optimized condition with a little WV additive.

A rabbit model of implant-related osteomyelitis inoculated with biofilm after open femoral fracture

PubMed Central

Zhang, Xiang; Ma, Yun-Fei; Wang, Lei; Jiang, Nan; Qin, Cheng-He; Hu, Yan-Jun; Yu, Bin

2017-01-01

Currently, animal models used in research on implant-associated osteomyelitis primarily use intramedullary fixation and initial inoculum of planktonic bacterial cells. However, these techniques have certain limitations, including lack of rotational stability and instable inoculation. To improve these models, the present study aimed to establish a novel rabbit model of implant-associated osteomyelitis using biofilm as the initial inoculum following plate fixation of the femoral fracture. A total of 24 New Zealand White rabbits were randomly divided into two equal groups. Osteotomy was performed at the right femoral shaft using a wire saw following fixation with a 5-hole stainless steel plate. The plates were not colonized with bacteria in group 1, but colonized with a biofilm of Staphylococcus aureus (American Type Culture Collection, 25923) in group 2. All the rabbits were sacrificed after 21 days for clinical, X-ray, micro-computed tomography and histological assessments of the severity of osteomyelitis. Scanning electron microscopy and confocal laser scanning microscopy were used for biofilm assessment. In group 2, pus formation, periosteal reaction, cortical destruction and absorption were observed in all the rabbits and biofilm formation was observed on all the plates. However, no pus formation was observed except for a slight inflammatory response and all the plates appeared clean without infection in group 1. The differences between the two groups were statistically significant regarding histologic scores and semi-quantification of the bacteria on the plates (P<0.001). In the present study, a novel rabbit model of infection following internal plate fixation of open fracture was successfully established, providing a novel tool for the study of implant-associated osteomyelitis. PMID:29201204

Using common mycorrhizal networks for controlled inoculation of Quercus spp. with Tuber melanosporum: the nurse plant method.

PubMed

Pereira, Guillermo; Palfner, Götz; Chávez, Daniel; Suz, Laura M; Machuca, Angela; Honrubia, Mario

2013-07-01

The high cost and restricted availability of black truffle spore inoculum for controlled mycorrhiza formation of host trees produced for truffle orchards worldwide encourage the search for more efficient and sustainable inoculation methods that can be applied globally. In this study, we evaluated the potential of the nurse plant method for the controlled inoculation of Quercus cerris and Quercus robur with Tuber melanosporum by mycorrhizal networks in pot cultures. Pine bark compost, adjusted to pH 7.8 by liming, was used as substrate for all assays. Initially, Q. robur seedlings were inoculated with truffle spores and cultured for 12 months. After this period, the plants presenting 74 % mycorrhizal fine roots were transferred to larger containers. Nurse plants were used for two treatments of two different nursling species: five sterilized acorns or five 45-day-old, axenically grown Q. robur or Q. cerris seedlings, planted in containers around the nurse plant. After 6 months, colonized nursling plant root tips showed that mycorrhiza formation by T. melanosporum was higher than 45 % in the seedlings tested, with the most successful nursling combination being Q. cerris seedlings, reaching 81 % colonization. Bulk identification of T. melanosporum mycorrhizae was based on morphological and anatomical features and confirmed by sequencing of the internal transcribed spacer region of the ribosomal DNA of selected root tips. Our results show that the nurse plant method yields attractive rates of mycorrhiza formation by the Périgord black truffle and suggest that establishing and maintaining common mycorrhizal networks in pot cultures enables sustained use of the initial spore inoculum.

Biosolids accumulation and biodegradation of domestic wastewater treatment plant sludge by developed liquid state bioconversion process using a batch fermenter.

PubMed

Alam, Md Zahangir; Fakhru'l-Razi, A; Molla, Abul H

2003-09-01

The biosolids accumulation and biodegradation of domestic wastewater treatment plant (DWTP) sludge by filamentous fungi have been investigated in a batch fermenter. The filamentous fungi Aspergillus niger and Penicillium corylophilum isolated from wastewater and DWTP sludge was used to evaluate the treatment performance. The optimized mixed inoculum (A. niger and P. corylophilum) and developed process conditions (co-substrate and its concentration, temperature, initial pH, inoculum size, and aeration and agitation rate) were incorporated to accelerate the DWTP sludge treatment process. The results showed that microbial treatment of higher strength of DWTP sludge (4% w/w of TSS) was highly influenced by the liquid state bioconversion (LSB) process. In developed bioconversion processes, 93.8 g/kg of biosolids was enriched with fungal biomass protein of 30 g/kg. Enrichment of nutrients such as nitrogen (N), phosphorous (P), potassium (K) in biosolids was recorded in 6.2% (w/w), 3.1% (w/w) and 0.15% (w/w) from its initial values of 4.8% (w/w), 2.0% (w/w) and 0.08% (w/w) respectively after 10 days of fungal treatment. The biodegradation results revealed that 98.8% of TSS, 98.2% of TDS, 97.3% of turbidity, 80.2% of soluble protein, 98.8% of reducing sugar and 92.7% of COD in treated DWTP sludge supernatant were removed after 8 days of microbial treatment. The specific resistance to filtration (SRF) in treated sludge (1.4x10(12) m/kg) was decreased tremendously by the microbial treatment of DWTP sludge after 6 days of fermentation compared to untreated sample (85x10(12) m/kg).

Induction of sporulation and the influence of time, temperature, and inoculum size on growth in two species of aquatic fungi (Saprolegniales)

USGS Publications Warehouse

Bailey, T.A.; Bradford, K.; Bland, C.E.

1990-01-01

Because the infective stage of most mycoses of aquatic organisms is the zoospore, we attempted to establish optimum conditions under which zoospores could be produced for use in antifungal testing. Optimum sporulation time, incubation time, inoculum size, and growth temperature were determined for each oftwo saprolegniaceous fungi, Achlya flagellata Coker and Saprolegnia hypogyna (Pringsheim) de Bary. Both species produced the largest number of zoospores after 18 hours (51.7 spores/ml for A. jlagellata and 848.0 spores/ml for S. hypogyna), and yielded maximum growth after 48 hours at 22 'C. The recommended test inoculum size for S. hypogyna (5,600 spores/ml was nearly three times that for A. flagellata (2,000 spores/ml),

Effect of fermentation conditions on biohydrogen production from cassava starch by anaerobic mixed cultures

NASA Astrophysics Data System (ADS)

Tien, Hai M.; Le, Kien A.; Tran, An T.; Le, Phung K.

2016-06-01

In this work, a series of batch tests were conducted to investigate the effect of pH, temperature, fermentation time, and inoculums ratio to hydrogen production using cassava starch as a substrate. The statistical analysis of the experiment indicated that the significant effects for the fermentation yield were the main effect of temperature, pH and inoculums ratio. It was fouund that the suitable fermentation conditions of biohydrogen production should be at temperature 40 ° C; pH 6.5, inoculums to medium ratio 10 % and COD operation at 4800 g/mL. The maximum value of hydrogen volume produced was 76.22 mL. These affected has been evaluated and the result can be used as an reference for the pilot or industrial biohydrogen production.

Simultaneous influenza and respiratory syncytial virus infection in human respiratory tract

NASA Astrophysics Data System (ADS)

Pinky, Lubna Jahan Rashid; Dobrovolny, Hana

2015-03-01

Studies have shown that simultaneous infection of the respiratory tract with at least two viruses is not uncommon in hospitalized patients, although it is not clear whether these infections are more or less severe than single infections. We use mathematical models to study the dynamics of simultaneous influenza (flu) and respiratory syncytial virus (RSV) infection, two of the more common respiratory viruses, in an effort to understand simultaneous infections. We examine the roles of initial viral inoculum, relative starting time, and cell regeneration on the severity of the infection. We also study the effect of antiviral treatment on the course of the infection. This study shows that, unless treated with antivirals, flu always takes over the infection no matter how small the initial dose and how delayed it starts with respect to RSV.

Production of lipopeptides by Bacillus amyloliquefaciens XZ-173 in solid state fermentation using soybean flour and rice straw as the substrate.

PubMed

Zhu, Zhen; Zhang, Guoyi; Luo, Yi; Ran, Wei; Shen, Qirong

2012-05-01

This work was aimed to produce lipopeptides by Bacillus amyloliquefaciens XZ-173 in solid state fermentation using agro-industrial byproducts. A central composite design was used to get the highest lipopeptides production. Results revealed that the optimal conditions for maximum lipopeptides production were 1.79% starch and 1.91% yeast extract by employing 5.58 g soybean flour and 3.67 g rice straw as the solid substrate with initial pH 7.5, moisture content 55% and a 10% inoculum level at 30°C for 2 days. Under these conditions, the experimental yield of lipopeptides reached 50.01 mg/gds, which was very close to the predicted value (49.91 mg/gds). At high concentration, the lipopeptides extracted from fermented substrates showed strong antibiotic activity against Rhizoctonia solani and Ralstonia solanacearum and certain emulsification but good emulsion stability. This is the first report on lipopeptides production that uses rice straw as a major substrate. Copyright © 2012 Elsevier Ltd. All rights reserved.

Effect of high-temperature, short-time (HTST) pasteurization on milk containing low numbers of Mycobacterium paratuberculosis.

PubMed

Grant, I R; Ball, H J; Rowe, M T

1998-02-01

The efficacy of high-temperature, short-time (HTST) pasteurization (72 degrees C/15 s) when low numbers (< or = 10(3) cfu ml-1) of Mycobacterium paratuberculosis are present in milk was investigated. Raw cows' milk spiked with Myco. paratuberculosis (10(3) cfu ml-1, 10(2) cfu ml-1, 10 cfu ml-1, and 10 cfu 50 ml-1) was subjected to HTST pasteurization using laboratory pasteurizing units. Ten bovine strains of Myco. paratuberculosis were tested in triplicate. Culture in BACTEC Middlebrook 12B radiometric medium detected acid-fast survivors in 14.8% and 10% of HTST-pasteurized milk samples at the 10(3) and 10(2) cfu ml-1 inoculum levels, respectively, whereas conventional culture on Herrold's egg yolk medium containing mycobactin J detected acid-fast survivors in only 3.7% and 6.7% of the same milk samples. IS900-based PCR confirmed that these acid-fast survivors were Myco. paratuberculosis. No viable Myco. paratuberculosis were isolated from HTST-pasteurized milk initially containing either 10 cfu ml-1 or 10 cfu 50 ml-1.

Development of a microbial time/temperature indicator prototype for monitoring the microbiological quality of chilled foods.

PubMed

Vaikousi, Hariklia; Biliaderis, Costas G; Koutsoumanis, Konstantinos P

2008-05-01

A time/temperature indicator (TTI) system based on the growth and metabolic activity of a Lactobacillus sakei strain was developed for monitoring food quality throughout the chilled-food chain. In the designed system, an irreversible color change of a chemical chromatic indicator (from red to yellow) progressively occurs due to the pH decline that results from microbial growth and metabolism in a selected medium. The relation of the TTI response (color change) to the growth and metabolic activity (glucose consumption, lactic acid production, pH decrease) of L. sakei was studied. In addition, the temperature dependence of the TTI kinetics was investigated isothermally in the range of 0 to 16 degrees C and modeled with a system of differential equations. At all temperatures tested, the pH and color changes of the TTI system followed closely the growth of L. sakei, with the endpoint (the time at which a distinct visual color change to the final yellow was observed) of the TTI coinciding with a population level of 10(7) to 10(8) CFU/ml. The endpoint decreased from 27 days at 0 degrees C to 2.5 days at 16 degrees C, yielding an activation energy of 97.7 kJ/mol, which was very close to the activation energy of the L. sakei growth rate in the TTI substrate (103.2 kJ/mol). Furthermore, experiments conducted on the effect of the inoculum level showed a negative linear relationship between the level of L. sakei inoculated in the system medium and the endpoint of the TTI. For example, the endpoint at 8 degrees C ranged from 6 to 2 days for inoculum levels of 10(1) and 10(6) CFU/ml, respectively. This relationship allows the easy adjustment of the TTI endpoint at a certain temperature according to the shelf life of the food product of concern by using an appropriate inoculum level of L. sakei. The microbial TTI prototype developed in the present study could be used as an effective tool for monitoring shelf life during the distribution and storage of food products that are spoiled primarily by lactic acid bacteria or other bacteria exhibiting similar kinetic responses and spoilage potentials. Apart from the low cost, the main advantage of the proposed TTI is that its response closely matches the loss of the quality of a food product by simulating the microbial spoilage process in particular environments.

Development of a Microbial Time/Temperature Indicator Prototype for Monitoring the Microbiological Quality of Chilled Foods▿

PubMed Central

Vaikousi, Hariklia; Biliaderis, Costas G.; Koutsoumanis, Konstantinos P.

2008-01-01

A time/temperature indicator (TTI) system based on the growth and metabolic activity of a Lactobacillus sakei strain was developed for monitoring food quality throughout the chilled-food chain. In the designed system, an irreversible color change of a chemical chromatic indicator (from red to yellow) progressively occurs due to the pH decline that results from microbial growth and metabolism in a selected medium. The relation of the TTI response (color change) to the growth and metabolic activity (glucose consumption, lactic acid production, pH decrease) of L. sakei was studied. In addition, the temperature dependence of the TTI kinetics was investigated isothermally in the range of 0 to 16°C and modeled with a system of differential equations. At all temperatures tested, the pH and color changes of the TTI system followed closely the growth of L. sakei, with the endpoint (the time at which a distinct visual color change to the final yellow was observed) of the TTI coinciding with a population level of 107 to 108 CFU/ml. The endpoint decreased from 27 days at 0°C to 2.5 days at 16°C, yielding an activation energy of 97.7 kJ/mol, which was very close to the activation energy of the L. sakei growth rate in the TTI substrate (103.2 kJ/mol). Furthermore, experiments conducted on the effect of the inoculum level showed a negative linear relationship between the level of L. sakei inoculated in the system medium and the endpoint of the TTI. For example, the endpoint at 8°C ranged from 6 to 2 days for inoculum levels of 101 and 106 CFU/ml, respectively. This relationship allows the easy adjustment of the TTI endpoint at a certain temperature according to the shelf life of the food product of concern by using an appropriate inoculum level of L. sakei. The microbial TTI prototype developed in the present study could be used as an effective tool for monitoring shelf life during the distribution and storage of food products that are spoiled primarily by lactic acid bacteria or other bacteria exhibiting similar kinetic responses and spoilage potentials. Apart from the low cost, the main advantage of the proposed TTI is that its response closely matches the loss of the quality of a food product by simulating the microbial spoilage process in particular environments. PMID:18326676

Effects of inoculum source and co-digestion strategies on anaerobic digestion of residues generated in the treatment of waste vegetable oils.

PubMed

Hidalgo, Dolores; Martín-Marroquín, Jesús M

2014-09-01

This work aims at selecting a suitable strategy to improve the performance of the anaerobic digestion of residues generated in the treatment of waste vegetable oils (WVO). Biochemical methane potential (BMP) assays were conducted at 35 °C to evaluate the effects of substrate mix ratio between a mixture of WVO residues (M) and pig manure (PM) co-digesting by using different inocula. Inoculum from an industrial digester fed with organic waste from hotels, restaurants and catering leftovers (HORECA) showed higher methanogenic activity (55.5 mLCH4 gVS(-1) d(-1)) than municipal wastewater treatment plant (mWWTP) inoculum (42.6 mL CH4 gVS(-1) d(-1)). Furthermore, the results showed that the resistance to WVO residues toxicity was higher for the HORECA sludge than for the mWWTP sludge. HORECA inoculum produced more biogas in all the assays. Moreover, the resulting biogas was of better quality, containing an average of 71.1% (SD = 1.6) methane compared to an average of 69.5% (SD = 1.2) methane for test with mWWTP sludge. The maximum degradation rate occurred at the higher PM mix ratio (M/PM:1/3), reaching 26.7 ± 4.3 mLCH4 gVS(-1) d(-1) for mWWTP inoculum, versus 42.0 ± 1,5 mLCH4 gVS(-1) d(-1) achieved for HORECA inoculum. A high reduction of volatile solids (between 70% and 81%) was obtained with both inocula at all M/PM ratios assayed (1/0, 1/3, 1/1 and 3/1 v/v) but, bearing in mind the operation of a full-scale anaerobic plant, the optimal scenario assayed corresponds to the ratio M/PM: 1/3 v/v where shorter lag periods will make it possible to operate at lower hydraulic retention times. Copyright © 2014 Elsevier Ltd. All rights reserved.

Enterocin HZ produced by a wild Enterococcus faecium strain isolated from a traditional, starter-free pickled cheese.

PubMed

Yildirim, Zeliha; Bilgin, Harun; Isleroglu, Hilal; Tokatli, Kader; Sahingil, Didem; Yildirim, Metin

2014-05-01

Bacteriogenic Enterococcus faecium HZ was identified by using biochemical (Strep-API 20, API-50 CHL, fatty acid profile) and 16S rRNA analysis (99·99 %). Ent. faecium HZ was sensitive to clinically important antibiotics such as vancomycin, and did not have gelatinase and haemolysis activities. Enterocin HZ, a bacteriocin from Ent. faecium HZ, was sensitive to papain and tyripsin, but resistant to pepsin, lipase, catalase, α-amylase, organic solvents, detergents, ß-mercaptoethanol, and heat treatment (90 °C/30 min). It was biologically active at pH 2·0-9·0 and synthesised at the highest level in MRS or M17 broth at 32 or 37 °C with an inoculum amount of 0·1-0·5 % and an initial pH of 6·0-7·0. Enterocin HZ production reached maximum level at middle and late logarithmic phase and its molecular weight was ∼4·5 kDa. It was active against some Gram-positive foodborne bacteria. Ent. faecium HZ or its bacteriocin enterocin HZ is a good candidate to be studied as a food biopreservative since enterocin HZ showed strong bactericidal activity against Listeria monocytogenes in UHT milk and also Ent. faecium HZ grew very well in milk and produced enterocin HZ at maximum level.

Persistence of Mycobacterium paratuberculosis during Manufacture and Ripening of Cheddar Cheese

PubMed Central

Donaghy, J. A.; Totton, N. L.; Rowe, M. T.

2004-01-01

Model Cheddar cheeses were prepared from pasteurized milk artificially contaminated with high 104 to 105 CFU/ml) and low (101 to 102 CFU/ml) inocula of three different Mycobacterium paratuberculosis strains. A reference strain, NCTC 8578, and two strains (806PSS and 796PSS) previously isolated from pasteurized milk for retail sale were investigated in this study. The manufactured Cheddar cheeses were similar in pH, salt, moisture, and fat composition to commercial Cheddar. The survival of M. paratuberculosis cells was monitored over a 27-week ripening period by plating homogenized cheese samples onto HEYM agar medium supplemented with the antibiotics vancomycin, amphotericin B, and nalidixic acid without a decontamination step. A concentration effect was observed in M. paratuberculosis numbers between the inoculated milk and the 1-day old cheeses for each strain. For all manufactured cheeses, a slow gradual decrease in M. paratuberculosis CFU in cheese was observed over the ripening period. In all cases where high levels (>3.6 log10) of M. paratuberculosis were present in 1-day cheeses, the organism was culturable after the 27-week ripening period. The D values calculated for strains 806PSS, 796PSS, and NCTC 8578 were 107, 96, and 90 days, respectively. At low levels of contamination, M. paratuberculosis was only culturable from 27-week-old cheese spiked with strain 806PSS. M. paratuberculosis was recovered from the whey fraction in 10 of the 12 manufactured cheeses. Up to 4% of the initial M. paratuberculosis load was recovered in the culture-positive whey fractions at either the high or low initial inoculum. PMID:15294829

Use of disposable reactors to generate inoculum cultures for E. coli production fermentations.

PubMed

Mahajan, Ekta; Matthews, Timothy; Hamilton, Ryan; Laird, Michael W

2010-01-01

Disposable technology is being used more each year in the biotechnology industry. Disposable bioreactors allow one to avoid expenses associated with cleaning, assembly and operations, as well as equipment validation. The WAVE bioreactor is well established for Chinese Hamster Ovary (CHO) production, however, it has not yet been thoroughly tested for E. coli production because of the high oxygen demand and temperature maintenance requirements of that platform. The objective of this study is to establish a robust process to generate inoculum for E. coli production fermentations in a WAVE bioreactor. We opted not to evaluate the WAVE system for production cultures because of the high cell densities required in our current E. coli production processes. Instead, the WAVE bioreactor 20/50 system was evaluated at laboratory scale (10-L) to generate inoculum with target optical densities (OD(550)) of 15 within 7-9 h (pre-established target for stainless steel fermentors). The maximum settings for rock rate (40 rpm) and angle (10.5) were used to maximize mass transfer. The gas feed was also supplemented with additional oxygen to meet the high respiratory demand of the culture. The results showed that the growth profiles for the inoculum cultures were similar to those obtained from conventional stainless steel fermentors. These inoculum cultures were subsequently inoculated into 10-L working volume stainless steel fermentors to evaluate the inocula performance of two different production systems during recombinant protein production. The results of these production cultures using WAVE inocula showed that the growth and recombinant protein production was comparable to the control data set. Furthermore, an economic analysis showed that the WAVE system would require less capital investment for installation and operating expenses would be less than traditional stainless steel systems. (c) 2010 American Institute of Chemical Engineers

Synergistic Killing of Multidrug-Resistant Pseudomonas aeruginosa at Multiple Inocula by Colistin Combined with Doripenem in an In Vitro Pharmacokinetic/Pharmacodynamic Model ▿

PubMed Central

Bergen, Phillip J.; Tsuji, Brian T.; Bulitta, Jurgen B.; Forrest, Alan; Jacob, Jovan; Sidjabat, Hanna E.; Paterson, David L.; Nation, Roger L.; Li, Jian

2011-01-01

Combination therapy may be required for multidrug-resistant (MDR) Pseudomonas aeruginosa. The aim of this study was to systematically investigate bacterial killing and emergence of colistin resistance with colistin and doripenem combinations against MDR P. aeruginosa. Studies were conducted in a one-compartment in vitro pharmacokinetic/pharmacodynamic model for 96 h at two inocula (∼106 and ∼108 CFU/ml) against a colistin-heteroresistant reference strain (ATCC 27853) and a colistin-resistant MDR clinical isolate (19147 n/m). Four combinations utilizing clinically achievable concentrations were investigated. Microbiological response was examined by log changes and population analysis profiles. Colistin (constant concentrations of 0.5 or 2 mg/liter) plus doripenem (peaks of 2.5 or 25 mg/liter every 8 h; half-life, 1.5 h) substantially increased bacterial killing against both strains at the low inoculum, while combinations containing colistin at 2 mg/liter increased activity against ATCC 27853 at the high inoculum; only colistin at 0.5 mg/liter plus doripenem at 2.5 mg/liter failed to improve activity against 19147 n/m at the high inoculum. Combinations were additive or synergistic against ATCC 27853 in 16 and 11 of 20 cases (4 combinations across 5 sample points) at the 106- and 108-CFU/ml inocula, respectively; the corresponding values for 19147 n/m were 16 and 9. Combinations containing doripenem at 25 mg/liter resulted in eradication of 19147 n/m at the low inoculum and substantial reductions in regrowth (including to below the limit of detection at ∼50 h) at the high inoculum. Emergence of colistin-resistant subpopulations of ATCC 27853 was substantially reduced and delayed with combination therapy. This investigation provides important information for optimization of colistin-doripenem combinations. PMID:21911563

Microbial community composition and electricity generation in cattle manure slurry treatment using microbial fuel cells: effects of inoculum addition.

PubMed

Xie, Binghan; Gong, Weijia; Ding, An; Yu, Huarong; Qu, Fangshu; Tang, Xiaobin; Yan, Zhongsen; Li, Guibai; Liang, Heng

2017-10-01

Microbial fuel cell (MFC) is a sustainable technology to treat cattle manure slurry (CMS) for converting chemical energy to bioelectricity. In this work, two types of allochthonous inoculum including activated sludge (AS) and domestic sewage (DS) were added into the MFC systems to enhance anode biofilm formation and electricity generation. Results indicated that MFCs (AS + CMS) obtained the maximum electricity output with voltage approaching 577 ± 7 mV (~ 196 h), followed by MFCs (DS + CMS) (520 ± 21 mV, ~ 236 h) and then MFCs with autochthonous inoculum (429 ± 62 mV, ~ 263.5 h). Though the raw cattle manure slurry (RCMS) could facilitate electricity production in MFCs, the addition of allochthonous inoculum (AS/DS) significantly reduced the startup time and enhanced the output voltage. Moreover, the maximum power (1.259 ± 0.015 W/m 2 ) and the highest COD removal (84.72 ± 0.48%) were obtained in MFCs (AS + CMS). With regard to microbial community, Illumina HiSeq of the 16S rRNA gene was employed in this work and the exoelectrogens (Geobacter and Shewanella) were identified as the dominant members on all anode biofilms in MFCs. For anode microbial diversity, the MFCs (AS + CMS) outperformed MFCs (DS + CMS) and MFCs (RCMS), allowing the occurrence of the fermentative (e.g., Bacteroides) and nitrogen fixation bacteria (e.g., Azoarcus and Sterolibacterium) which enabled the efficient degradation of the slurry. This study provided a feasible strategy to analyze the anode biofilm formation by adding allochthonous inoculum and some implications for quick startup of MFC reactors for CMS treatment.

Identification of Unequally Represented Founder Viruses Among Tissues in Very Early SIV Rectal Transmission

PubMed Central

Chen, Jian; Ren, Yanqin; Daharsh, Lance; Liu, Lu; Kang, Guobin; Li, Qingsheng; Wei, Qiang; Wan, Yanmin; Xu, Jianqing

2018-01-01

Characterizing the transmitted/founder (T/F) viruses of multi-variant SIV infection may shed new light on the understanding of mucosal transmission. We intrarectally inoculated six Chinese rhesus macaques with a single high dose of SIVmac251 (3.1 × 104 TCID50) and obtained 985 full-length env sequences from multiple tissues at 6 and 10 days post-infection by single genome amplification (SGA). All 6 monkeys were infected with a range of 2 to 8 T/F viruses and the dominant variants from the inoculum were still dominant in different tissues from each monkey. Interestingly, our data showed that a cluster of rare T/F viruses was unequally represented in different tissues. This cluster of rare T/F viruses phylogenetically related to the non-dominant SIV variants in the inoculum and was not detected in any rectum tissues, but could be identified in the descending colon, jejunum, spleen, or plasma. In 2 out of 6 macaques, identical SIVmac251 variants belonging to this cluster were detected simultaneously in descending colon/jejunum and the inoculum. We also demonstrated that the average CG dinucleotide frequency of these rare T/F viruses found in tissues, as well as non-dominant variants in the inoculum, was significantly higher than the dominant T/F viruses in tissues and the inoculum. Collectively, these findings suggest that descending colon/jejunum might be more susceptible than rectum to SIV in the very early phase of infection. And host CG suppression, which was previously shown to inhibit HIV replication in vitro, may also contribute to the bottleneck selection during in vivo transmission. PMID:29651274

The effect of particle size and amount of inoculum on fungal treatment of wheat straw and wood chips.

PubMed

van Kuijk, Sandra J A; Sonnenberg, Anton S M; Baars, Johan J P; Hendriks, Wouter H; Cone, John W

2016-01-01

The aim of this study was to optimize the fungal treatment of lignocellulosic biomass by stimulating the colonization. Wheat straw and wood chips were treated with Ceriporiopsis subvermispora and Lentinula edodes with various amounts of colonized millet grains (0.5, 1.5 or 3.0 % per g of wet weight of substrate) added to the substrates. Also, wheat straw and wood chips were chopped to either 0.5 or 2 cm. Effectiveness of the fungal treatment after 0, 2, 4, 6, or 8 wk of incubation was determined by changes in chemical composition, in vitro gas production (IVGP) as a measure for rumen degradability, and ergosterol content as a measure of fungal biomass. Incomplete colonization was observed for C. subvermispora treated wheat straw and L. edodes treated wood chips. The different particle sizes and amounts of inoculum tested, had no significant effects on the chemical composition and the IVGP of C. subvermispora treated wood chips. Particle size did influence L. edodes treatment of wheat straw. The L. edodes treatment of 2 cm wheat straw resulted in a more selective delignification and a higher IVGP than the smaller particles. Addition of 1.5 % or 3 % L. edodes inoculum to wheat straw resulted in more selective delignification and a higher IVGP than addition of 0.5 % inoculum. Particle size and amount of inoculum did not have an effect on C. subvermispora treatment of wood chips. At least 1.5 % L. edodes colonized millet grains should be added to 2 cm wheat straw to result in an increased IVGP and acid detergent lignin (ADL) degradation.

Recovery of surface bacteria from and surface sanitization of cantaloupes.

PubMed

Barak, Jeri D; Chue, Bryan; Mills, Daniel C

2003-10-01

Practical, effective methods that could be implemented in a food service establishment (restaurant or delicatessen) for the surface sanitization of cantaloupes were microbiologically evaluated. Cantaloupes (Cucumis melo L. var. reticulates) were immersed in an inoculum containing Salmonella enterica serovar Poona or Pantoea agglomerans at ca. 10(4) to 10(5) CFU/ml. An efficient method for the recovery of bacteria from the cantaloupe surface was developed and validated. The method consisted of washing the entire melon with Butterfield's buffer containing 1% Tween 80 in a plastic bag placed inside a plastic pail affixed to an orbital shaker. Levels of S. enterica Poona recovered by washing the entire melon were significantly higher than those recovered by the more common laboratory method of blending the rind. P. agglomerans can be used as a non-pathogenic proxy for S. enterica Poona. A three-compartment surface sanitization method consisting of washing with an antimicrobial soap solution, scrubbing with a brush in tap water, and immersion in 150 ppm of sodium hypochlorite reduced the initial level of recoverable viable bacteria by 99.8%. When examined separately, scrubbing with a vegetable brush in tap water, washing with soap, and dipping in chlorine were found to reduce the bacterial load by 70, 80, and 90%, respectively.

Impact of pitching rate on yeast fermentation performance and beer flavour.

PubMed

Verbelen, P J; Dekoninck, T M L; Saerens, S M G; Van Mulders, S E; Thevelein, J M; Delvaux, F R

2009-02-01

The volumetric productivity of the beer fermentation process can be increased by using a higher pitching rate (i.e. higher inoculum size). However, the impact of the pitching rate on crucial fermentation and beer quality parameters has never been assessed systematically. In this study, five pitching rates were applied to lab-scale fermentations to investigate its impact on the yeast physiology and beer quality. The fermentation rate increased significantly and the net yeast growth was lowered with increasing pitching rate, without affecting significantly the viability and the vitality of the yeast population. The build-up of unsaturated fatty acids in the initial phase of the fermentation was repressed when higher yeast concentrations were pitched. The expression levels of the genes HSP104 and HSP12 and the concentration of trehalose were higher with increased pitching rates, suggesting a moderate exposure to stress in case of higher cell concentrations. The influence of pitching rate on aroma compound production was rather limited, with the exception of total diacetyl levels, which strongly increased with the pitching rate. These results demonstrate that most aspects of the yeast physiology and flavour balance are not significantly or negatively affected when the pitching rate is changed. However, further research is needed to fully optimise the conditions for brewing beer with high cell density populations.

Ammonia tolerant inocula provide a good base for anaerobic digestion of microalgae in third generation biogas process.

PubMed

Mahdy, Ahmed; Fotidis, Ioannis A; Mancini, Enrico; Ballesteros, Mercedes; González-Fernández, Cristina; Angelidaki, Irini

2017-02-01

This study investigated the ability of an ammonia-acclimatized inoculum to digest efficiently protein-rich microalgae for continuous 3rd generation biogas production. Moreover, we investigated whether increased C/N ratio could alleviate ammonia toxicity. The biochemical methane potential (BMP) of five different algae (Chlorella vulgaris)/manure (cattle) mixtures showed that the mixture of 80/20 (on VS basis) resulted in the highest BMP value (431mLCH 4 gVS -1 ), while the BMP of microalgae alone (100/0) was 415mLCH 4 gVS -1 . Subsequently, anaerobic digestion of those two substrates was tested in continuous stirred tank reactors (CSTR). Despite of the high ammonium levels (3.7-4.2g NH 4 + -NL -1 ), CSTR reactors using ammonia tolerant inoculum resulted in relatively high methane yields (i.e. 77.5% and 84% of the maximum expected, respectively). These results demonstrated that ammonia tolerant inocula could be a promising approach to successfully digest protein-rich microalgae and achieve a 3rd generation biogas production. Copyright © 2016 Elsevier Ltd. All rights reserved.

Influence of Aphelenchus avenae on Vesicular-arbuscular Endomycorrhizal Growth Response in Cotton.

PubMed

Hussey, R S; Roncadori, R W

1981-01-01

The influence of Aphelenchus avenae on the relationship between cotton (Gossypium hirsutum 'Stoneville 213') and Gigaspora margarita or Glomus etunicatus was assessed by its effect on the mycorrhizal stimulation of plant growth and microorganism reproduction. The mycophagous nematode usually did not suppress stimulation of shoot growth resulting from mycorrhizae (G. margarita) at inoculum levels of 3,000 or 6,000 nematodes per pot, but retarded root growth at 6,000 per pot. When the nematode inoculum was increased to 10, 40, or 80 thousand, G. margarita stimulation of shoot or root growth was retarded at the two higher rates. Shoot growth enhancement by G. etunicatus was suppressed by 10 thousand A. avenae but not by 40 or 80 thousand. A. avenae reproduced better when the nematode was added 3 wk after G. margarita than with simultaneous inoculations. Sporulation of both fungi was affected little by the mycophagous nematode. The high numbers of A. avenae required for an antagonistic effect probably precludes the occurrence of any significant interaction between these two organisms under field conditions.

The use of Design of Experiments and Response Surface Methodology to optimize biomass and lipid production by the oleaginous marine green alga, Nannochloropsis gaditana in response to light intensity, inoculum size and CO2.

PubMed

Hallenbeck, Patrick C; Grogger, Melanie; Mraz, Megan; Veverka, Donald

2015-05-01

Biodiesel produced from microalgal lipids is being considered as a potential source of renewable energy. However, a number of hurdles will have to be overcome if such a process is to become practical. One important factor is the volumetric production of biomass and lipid that can be achieved. The marine alga Nannochloropsis gaditana is under study since it is known to be highly oleaginous and has a number of other attractive properties. Factors that might be important in biomass and lipid production by this alga are light intensity, inoculum size and CO2. Here we have carried out for the first time a RSM-DOE study of the influence of these important culture variables and define conditions that maximize biomass production, lipid content (BODIPY® fluorescence) and total lipid production. Moreover, flow cytometry allowed the examination on a cellular level of changes that occur in cellular populations as they age and accumulate lipids. Copyright © 2014 Elsevier Ltd. All rights reserved.

Comparison of microbially enhanced compost extracts produced from composted cattle rumen content material and from commercially available inocula.

PubMed

Shrestha, Karuna; Adetutu, Eric M; Shrestha, Pramod; Walsh, Kerry B; Harrower, Keith M; Ball, Andrew S; Midmore, David J

2011-09-01

A comparative study was performed on compost extracts prepared from cattle rumen content composted for three and nine months, nine month old compost inoculated with a Nutri-Life 4/20™ inoculum, and two commercial preparations (LivingSoil™ and Nutri-Life 4/20™), all incubated for 48h. Nutri-Life 4/20™ had the highest concentrations of NO(3)(-)-N and K(+)-K, while rumen compost extract had higher humic and fulvic acids concentration. The bacterial and fungal community level functional diversity of three month old compost extract and of LivingSoil™, assessed with Biolog™, were higher than that of nine month old rumen compost extract, with or without Nutri-Life 4/20™ inoculum, or Nutri-Life 4/20™. No difference in fungal diversity was observed between treatments, as indicated by Denaturing Gradient Gel Electrophoresis (DGGE) analysis, however, bacterial diversity was higher in all compost extracts and LivingSoil™ compared to the Nutri-Life 4/20™. Criteria for judging the quality of a microbially enhanced extract are discussed. Copyright © 2011 Elsevier Ltd. All rights reserved.

Parameters for determining inoculated pack/challenge study protocols.

PubMed

2010-01-01

The National Advisory Committee on Microbiological Criteria for Foods developed guidelines for conducting challenge studies on pathogen inhibition and inactivation studies in a variety of foods. The document is intended for use by the food industry, including food processors, food service operators, and food retailers; federal, state, and local food safety regulators; public health officials; food testing laboratories; and process authorities. The document is focused on and limited to bacterial inactivation and growth inhibition and does not make specific recommendations with respect to public health. The Committee concluded that challenge studies should be designed considering the most current advances in methodologies, current thinking on pathogens of concern, and an understanding of the product preparation, variability, and storage conditions. Studies should be completed and evaluated under the guidance of an expert microbiologist in a qualified laboratory and should include appropriate statistical design and data analyses. This document provides guidelines for choice of microorganisms for studies, inoculum preparation, inoculum level, methods of inoculation, incubation temperatures and times, sampling considerations, and interpreting test results. Examples of appropriately designed growth inhibition and inactivation studies are provided.

Evaluation of the 3M™ Petrifilm™ Salmonella express system for the detection of Salmonella species in selected foods: collaborative study.

PubMed

Bird, Patrick; Flannery, Jonathan; Crowley, Erin; Agin, James; Goins, David; Jechorek, Robert

2014-01-01

The 3M™ Petriflm™ Salmonella Express (SALX) System is a simple, ready-to-use chromogenic culture medium system for the rapid qualitative detection and biochemical confirmation of Salmonella spp. in food and food process environmental samples. The 3M Petrifilm SALX System was compared using an unpaired study design in a multilaboratory collaborative study to the U.S. Department of Agriculture/Food Safety and Inspection Service (USDA/FSIS) Microbiology Laboratory Guidebook (MLG) 4.07 (2013) Isolation and Identification of Salmonella from Meat, Poultry, Pasteurized Egg and Catfish Products and Carcass and Environmental Sponges for raw ground beef and the U.S. Food and Drug Administration Bacteriological Analytical Manual (FDA/BAM) Chapter 5, Salmonella (2011) reference method for dry dog food following the current AOAC validation guidelines. For this study, a total of 17 laboratories located throughout the continental United States evaluated 1872 test portions. For the 3M Petrifilm SALX System, raw ground beef was analyzed using 25 g test portions, and dry dog food was analyzed using 375 g test portions. For the reference methods, 25 g test portions of each inatrix were analyzed. The two matrices were artificially contaminated with Salmonella at three inoculation levels: an uninoculated control level (0 CFU/test portion), a low inoculum level (0.2-2 CFU/test portion), and a high inoculum level (2-5 CFU/test portion). Each inoculation level was statistically analyzed using the probability of detection statistical model. For the raw ground beef and dry dog food test portions, no significant differences at the 95% confidence interval were observed in the number of positive samples detected by the 3M Petrifilm SALX System versus either the USDA/FSIS-MLG or FDA/BAM methods.

New Tween-80 microbiological assay of serum folate levels in humans and animals.

PubMed

Zhou, Zhenghua; Yang, Yuan; Li, Ming; Kou, Chong; Xiao, Ping; Jiang, Yan; Hong, Junrong; Huang, Chengyu

2012-01-01

The objective of this study was to develop a new Tween-80 microbiological assay (Tween-80 MBA) to determine human or animal serum folate levels and to verify its reliability. The effects of the Lactobacillius casei subspecies rhamnosus (L. casei, ATCC No. 7469) inoculum concentration, incubation time, and Tween-80 on L. casei growth were studied, and the serum folate levels were investigated. Serum samples were collected from patients with esophageal cancer (EC) and healthy control subjects in Yanting, healthy adult subjects in Chengdu, Sichuan, and in male Sprague-Dawley rats. Optimal conditions for the new MBA were as follows: 1.28 x 10(7) CFU/mL working inoculum, vitamin folic acid assay broth with 0.24% (w/w) Tween-80, and anaerobic incubation with L. casei at 37 degrees C for 22 h. Under the optimal conditions, the working curve was in simple linear rather than logarithmic equation; the linear working curve of the folic acid standard working solution concentration versus the turbidity (adsorption value) of medium with L. casei ranged from 0.05 to 1.00 microg/L; the linear correlation coefficient was 0.9989 (SD 0.0007); the recovery rate of folate was 105.4-112.7%; and the minimum concentration for detecting folate was 0.03 microg/L. The RSD within-day and between-day precisions were 5.6 and 3.3%, respectively. The serum folate level of 100 EC patients was 6.4 (SEM 0.4) microg/L which was significantly lower than that of healthy control subjects [8.0 (SEM 0.6) microg/L, n = 100, P=0.020]. The new Tween-80 MBA is considered to be a reliable method for measuring serum folate level.

Association Between Weather Variables, Airborne Inoculum Concentration, and Raspberry Fruit Rot Caused by Botrytis cinerea.

PubMed

Carisse, Odile; McNealis, Vanessa; Kriss, Alissa

2018-01-01

Botrytis fruit rot (BFR), one of the most important diseases of raspberry (Rubus spp.), is controlled primarily with fungicides. Despite the use of fungicides, crop losses due to BFR are high in most years. The aim of this study was to investigate the association between airborne inoculum, weather variables, and BFR in order to improve the management of the disease as well as harvest and storage decisions. Crop losses, measured as the percentage of diseased berries during the harvest period, were monitored in unsprayed field plots at four sites in three successive years, together with meteorological data and the number of conidia in the air. Based on windowpane analysis, there was no evidence of correlation between crop losses and temperature, vapor pressure deficit, wind, solar radiation, or probability of infection. There were significant correlations between crop losses and airborne inoculum and between crop losses and humidity-related variables, and the best window length was identified as 7 days. Using 7-day average airborne inoculum concentration combined with 7-day average relative humidity for periods ending 6 to 8 days before bloom, it was possible to accurately predict crop losses (R 2 of 0.86 to 0.89). These models could be used to assist with managing BFR, timing harvests, and optimizing storage duration in raspberry crops.

Impact of organic loading rate on the performance of psychrophilic dry anaerobic digestion of dairy manure and wheat straw: long-term operation.

PubMed

Saady, Noori M Cata; Massé, Daniel I

2015-04-01

Development of efficient processes for valorising animal wastes would be a major advancement in cold-climate regions. This paper reports the results of long term (315 days experiment) of novel psychrophilic (20°C) dry anaerobic digestion (PDAD) of cow feces and wheat straw in laboratory scale sequence batch reactor operated at increasing organic loading rate. The PDAD process fed with a mixture of feces and straw (TS of 27%) over a treatment cycle length of 21 days at organic loading rate (OLR) 4.0, 5.0 and 6.0 g TCOD kg(-1) inoculum d(-1) (of 2.9 ± 0.1, 3.7 ± 0.1, and 4.4 ± 0.1g VS kg(-1) inoculum d(-1), respectively) resulted in average specific methane yield (SMY) of 187.3 ± 18.1, 163.6 ± 39.5, 150.8 ± 32.9 N L CH4 kg(-1)VS fed, respectively. PDAD of cow feces and wheat straw is possible with VS-based inoculum-to-substrate ratio of 1.4 at OLR of 6.0 g TCOD kg(-1) inoculum d(-1). Hydrolysis was the limiting step reaction. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

Suppression of Botrytis cinerea on necrotic grapevine tissues by early-season applications of natural products and biological control agents.

PubMed

Calvo-Garrido, Carlos; Viñas, Inmaculada; Elmer, Philip A G; Usall, Josep; Teixidó, Neus

2014-04-01

Necrotic tissues within grape (Vitis vinifera) bunches represent an important source of Botrytis cinerea inoculum for Botrytis bunch rot (BBR) at harvest in vineyards. This research quantified the incidence of B. cinerea on necrotic floral and fruit tissues and the efficacy of biologically based treatments for suppression of B. cinerea secondary inoculum within developing bunches. At veraison (2009 and 2010), samples of aborted flowers, aborted fruits and calyptras were collected, and the incidence and sporulation of B. cinerea were determined. Aborted fruits presented significantly higher incidence in untreated samples. Early-season applications of Candida sake plus Fungicover®, Fungicover alone or Ulocladium oudemansii significantly reduced B. cinerea incidence on aborted flowers and calyptras by 46-85%. Chitosan treatment significantly reduced B. cinerea incidence on calyptras. None of the treatments reduced B. cinerea incidence on aborted fruits. Treatments significantly reduced sporulation severity by 48% or more. Treatments were effective at reducing B. cinerea secondary inoculum on necrotic tissues, in spite of the variable control on aborted fruits. This is the first report to quantify B. cinerea on several tissues of bunch trash and to describe the effective suppression of saprophytic B. cinerea inoculum by biologically based treatments. © 2013 Society of Chemical Industry.

Microbial community dynamics and biogas production from manure fractions in sludge bed anaerobic digestion.

PubMed

Nordgård, A S R; Bergland, W H; Bakke, R; Vadstein, O; Østgaard, K; Bakke, I

2015-12-01

To elucidate how granular sludge inoculum and particle-rich organic loading affect the structure of the microbial communities and process performance in upflow anaerobic sludge bed (UASB) reactors. We investigated four reactors run on dairy manure filtrate and four on pig manure supernatant for three months achieving similar methane yields. The reactors fed with less particle rich pig manure stabilized faster and had highest capacity. Microbial community dynamics analysed by a PCR/denaturing gradient gel electrophoresis approach showed that influent was a major determinant for the composition of the reactor communities. Comparisons of pre- and non-adapted inoculum in the reactors run on pig manure supernatant showed that the community structure of the nonadapted inoculum adapted in approximately two months. Microbiota variance partitioning analysis revealed that running time, organic loading rate and inoculum together explained 26 and 31% of the variance in bacterial and archaeal communities respectively. The microbial communities of UASBs adapted to the reactor conditions in treatment of particle rich manure fractions, obtaining high capacity, especially on pig manure supernatant. These findings provide relevant insight into the microbial community dynamics in startup and operation of sludge bed reactors for methane production from slurry fractions, a major potential source of biogas. © 2015 The Society for Applied Microbiology.

The role of rain in dispersal of the primary inoculum of Plasmopara viticola.

PubMed

Rossi, Vittorio; Caffi, Tito

2012-02-01

Although primary infection of grapevines by Plasmopara viticola requires splash dispersal of inoculum from soil to leaves, little is known about the role of rain in primary inoculum dispersal. Distribution of rain splashes from soil to grapevine canopy was evaluated over 20 rain periods (0.2 to 64.2 mm of rain) with splash samplers placed within the canopy. Samplers at 40, 80, and 140 cm above the soil caught 4.4, 0.03, and 0.003 drops/cm(2) of sampler area, respectively. Drops caught at 40 and 80 cm (1.5 cm in diameter) were larger than drops at 140 cm (1.3 cm). Leaf coverage by splashed drops, total drop number, and drop size increased with an increase in the maximum intensity of rain (mm/h) during any rain period. Any rainfall led to infection in potted grapevines placed outside on leaf litter containing oospores, if the litter contained germinated oospores at the time of rain; infection severity was unrelated to rain amount or intensity. Results from vineyards also indicate that any rain can carry P. viticola inoculum from soil to leaves and should be considered a splash event in disease prediction systems. Sampling for early disease detection should focus on the lower canopy, where the probability of splash impact is greatest.

Kinetics of Coinfection with Influenza A Virus and Streptococcus pneumoniae

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, Amber M.; Adler, Frederick R.; Ribeiro, Ruy M.

Secondary bacterial infections are a leading cause of illness and death during epidemic and pandemic influenza. Experimental studies suggest a lethal synergism between influenza and certain bacteria, particularly Streptococcus pneumoniae, but the precise processes involved are unclear. In this paper, to address the mechanisms and determine the influences of pathogen dose and strain on disease, we infected groups of mice with either the H1N1 subtype influenza A virus A/Puerto Rico/8/34 (PR8) or a version expressing the 1918 PB1-F2 protein (PR8-PB1-F2(1918)), followed seven days later with one of two S. pneumoniae strains, type 2 D39 or type 3 A66.1. We determinedmore » that, following bacterial infection, viral titers initially rebound and then decline slowly. Bacterial titers rapidly rise to high levels and remain elevated. We used a kinetic model to explore the coupled interactions and study the dominant controlling mechanisms. We hypothesize that viral titers rebound in the presence of bacteria due to enhanced viral release from infected cells, and that bacterial titers increase due to alveolar macrophage impairment. Dynamics are affected by initial bacterial dose but not by the expression of the influenza 1918 PB1-F2 protein. Finally, our model provides a framework to investigate pathogen interaction during coinfections and to uncover dynamical differences based on inoculum size and strain.« less

Kinetics of Coinfection with Influenza A Virus and Streptococcus pneumoniae

DOE PAGES

Smith, Amber M.; Adler, Frederick R.; Ribeiro, Ruy M.; ...

2013-03-21

Secondary bacterial infections are a leading cause of illness and death during epidemic and pandemic influenza. Experimental studies suggest a lethal synergism between influenza and certain bacteria, particularly Streptococcus pneumoniae, but the precise processes involved are unclear. In this paper, to address the mechanisms and determine the influences of pathogen dose and strain on disease, we infected groups of mice with either the H1N1 subtype influenza A virus A/Puerto Rico/8/34 (PR8) or a version expressing the 1918 PB1-F2 protein (PR8-PB1-F2(1918)), followed seven days later with one of two S. pneumoniae strains, type 2 D39 or type 3 A66.1. We determinedmore » that, following bacterial infection, viral titers initially rebound and then decline slowly. Bacterial titers rapidly rise to high levels and remain elevated. We used a kinetic model to explore the coupled interactions and study the dominant controlling mechanisms. We hypothesize that viral titers rebound in the presence of bacteria due to enhanced viral release from infected cells, and that bacterial titers increase due to alveolar macrophage impairment. Dynamics are affected by initial bacterial dose but not by the expression of the influenza 1918 PB1-F2 protein. Finally, our model provides a framework to investigate pathogen interaction during coinfections and to uncover dynamical differences based on inoculum size and strain.« less

Relative effectiveness of kinetic analysis vs single point readings for classifying environmental samples based on community-level physiological profiles (CLPP)

NASA Technical Reports Server (NTRS)

Garland, J. L.; Mills, A. L.; Young, J. S.

2001-01-01

The relative effectiveness of average-well-color-development-normalized single-point absorbance readings (AWCD) vs the kinetic parameters mu(m), lambda, A, and integral (AREA) of the modified Gompertz equation fit to the color development curve resulting from reduction of a redox sensitive dye from microbial respiration of 95 separate sole carbon sources in microplate wells was compared for a dilution series of rhizosphere samples from hydroponically grown wheat and potato ranging in inoculum densities of 1 x 10(4)-4 x 10(6) cells ml-1. Patterns generated with each parameter were analyzed using principal component analysis (PCA) and discriminant function analysis (DFA) to test relative resolving power. Samples of equivalent cell density (undiluted samples) were correctly classified by rhizosphere type for all parameters based on DFA analysis of the first five PC scores. Analysis of undiluted and 1:4 diluted samples resulted in misclassification of at least two of the wheat samples for all parameters except the AWCD normalized (0.50 abs. units) data, and analysis of undiluted, 1:4, and 1:16 diluted samples resulted in misclassification for all parameter types. Ordination of samples along the first principal component (PC) was correlated to inoculum density in analyses performed on all of the kinetic parameters, but no such influence was seen for AWCD-derived results. The carbon sources responsible for classification differed among the variable types with the exception of AREA and A, which were strongly correlated. These results indicate that the use of kinetic parameters for pattern analysis in CLPP may provide some additional information, but only if the influence of inoculum density is carefully considered. c2001 Elsevier Science Ltd. All rights reserved.

A highly concentrated diet increases biogas production and the agronomic value of young bull's manure.

PubMed

Mendonça Costa, Mônica Sarolli Silva de; Lucas, Jorge de; Mendonça Costa, Luiz Antonio de; Orrico, Ana Carolina Amorim

2016-02-01

The increasing demand for animal protein has driven significant changes in cattle breeding systems, mainly in feedlots, with the use of young bulls fed on diets richer in concentrate (C) than in forage (F). These changes are likely to affect animal manure, demanding re-evaluation of the biogas production per kg of TS and VS added, as well as of its agronomic value as a biofertilizer, after anaerobic digestion. Here, we determined the biogas production and agronomic value (i.e., the macronutrient concentration in the final biofertilizer) of the manure of young bulls fed on diets with more (80% C+20% F; 'HighC' diet) or less (65% C+35% F; 'LowC' diet) concentrate, evaluating the effects of temperature (25, 35, and 40°C) and the use of an inoculum, during anaerobic digestion. A total of 24 benchtop reactors were used, operating in a semi-continuous system, with a 40-day hydraulic retention time (HRT). The manure from animals given the HighC diet had the greatest potential for biogas production, when digested with the use of an inoculum and at 35 or 40°C (0.6326 and 0.6207m(3)biogas/kg volatile solids, or VS, respectively). We observed the highest levels of the macronutrients N, P, and K in the biofertilizer from the manure of animals given HighC. Our results show that the manure of young bulls achieves its highest potential for biogas production and agronomic value when animals are fed diets richer in concentrate, and that biogas production increases if digestion is performed at higher temperatures, and with the use of an inoculum. Copyright © 2015 Elsevier Ltd. All rights reserved.

Preparation of a standardised faecal slurry for ex-vivo microbiota studies which reduces inter-individual donor bias.

PubMed

O'Donnell, Michelle M; Rea, Mary C; O'Sullivan, Órla; Flynn, Cal; Jones, Beth; McQuaid, Albert; Shanahan, Fergus; Ross, R Paul

2016-10-01

In-vitro gut fermentation systems provide suitable models for studying gut microbiota composition and functionality. However, such methods depend on the availability of donors and the assumption of reproducibility between microbial communities before experimental treatments commence. The aim of this study was to develop a frozen standardised inoculum (FSI) which minimizes inter-individual variation and to determine its stability over time using culture-dependent and culture-independent techniques. A method for the preparation difference of a FSI is described which involves pooling the faecal samples, centrifugation and pelleting of the cell biomass and finally homogenising the cell pellets with phosphate buffer and glycerol. Using this approach, no significant difference in total anaerobe cell viability was observed between the fresh standardised inoculum (before freezing) and the 12days post freezing FSI. Moreover, Quantitative PCR revealed no significant alterations in the estimated bacterial numbers in the FSI preparations for any of the phyla. MiSeq sequencing revealed minute differences in the relative abundance at phylum, family and genus levels between the FSI preparations. Differences in the microbiota denoted as significant were limited between preparations in the majority of cases to changes in percentage relative abundance of ±0.5%. The independently prepared FSIs revealed a high degree of reproducibility in terms of microbial composition between the three preparations. This study provides a method to produce a standardised human faecal inoculum suitable for freezing. Based on culture-dependent and independent analysis, the method ensures a degree of reproducibility between preparations by lessening the effect of inter-individual variation among the donors, thereby making the system more suitable for the accurate interpretation of the effects of experimental treatments. Copyright © 2016 Elsevier B.V. All rights reserved.

Optimization of the liquid biofertilizer production in batch fermentation with by-product from MSG

NASA Astrophysics Data System (ADS)

Namfon, Panjanapongchai; Ratchanok, Sahaworarak; Chalida, Daengbussade

2017-03-01

The long term use of chemical fertilizers destroyed the friability of soil which obviously decreased quantity and quality of crops and especially affect microorganisms living in soils. The bio-fertilizer with microbial consortium is an environmental friendly alternative to solve this bottleneck due to harboring soil microorganisms such as Bacillus sp., Micrococcus sp., Pseudomonas sp., Staphylococcus sp. and Deinococcus sp. produced with natural by-product or waste from industries that is alternative and sustainable such as nutrient-rich (by-product) from Mono Sodium Glutamate (MSG) for producing liquid biofertilizer by batch fermentation. In this work, the concentration of reducing sugar from substrate as main carbon source was evaluated in shake flask with mixed cultures. The optimal conditions were studied comparing with two levels of reducing sugar concentration (10, 20 g/L) and inoculums concentration (10, 20 %v/v) with using (2×2) full factorial design. The results indicated that the by-product from monosodium glutamate is feasible for fermentation and inoculums concentration is mainly influenced the batch fermentation process. Moreover, the combined 20 g/L and 10%v/v were considerably concluded as an optimal condition, of which the concentration of vegetative cells and spores attained at 8.29×109 CFU/mL and 1.97×105 CFU/mL, respectively. Their spores cell yields from reducing sugar (Yx/s) were obtained at 1.22×106 and 3.34×105 CFU/g were markedly different. In conclusion, the liquid Biofertilizer was produced satisfactorily at 20 g/L reducing sugar and 10% v/v inoculums in shake flask culture. Moreover, these results suggested that the by-product from monosodium glutamate is feasible for low-cost substrate in economical scale and environmental-friendly.

Comparative Study of the Effects of Citral on the Growth and Injury of Listeria innocua and Listeria monocytogenes Cells

PubMed Central

Silva-Angulo, Angela B.; Zanini, Surama F.; Rosenthal, Amauri; Rodrigo, Dolores; Klein, Günter; Martínez, Antonio

2015-01-01

This study investigates the effect of citral on growth and on the occurrence of sublethal damage in Listeria innocua Serovar 6a (CECT 910) and Listeria monocytogenes Serovar 4b (CECT 4032) cells that were exposed to citral as a natural antimicrobial agent. Two initial inoculum concentrations were considered in this investigation: 102 and 106 cfu/mL. Citral exhibited antilisterial activity against L. innocua and L. monocytogenes, and the observed effects were dependent on the concentration of citral present in the culture medium (0, 0.150 and 0.250 μL/mL) (p ≤ 0.05). L. innocua had a shorter lag phase than L. monocytogenes, and the two species had nearly identical maximum specific growth rates. These results indicate that L. innocua could be used as surrogate for L. monocytogenes when testing the effects of this antimicrobial. Significant differences in the lag phase and growth rate were observed between the small and large inoculum concentration (p ≤ 0.05). Citral-treated L. innocua and L. monocytogenes that were recovered on selective medium (i.e., TSA-YE-SC) had a shorter lag phase and a higher maximum specific growth rate than cells that were recovered on non-selective medium (i.e., TSA-YE) (p ≤ 0.05). This result suggests that damage occurs at sublethal concentrations of citral. PMID:25643164

Comparative study of the effects of citral on the growth and injury of Listeria innocua and Listeria monocytogenes cells.

PubMed

Silva-Angulo, Angela B; Zanini, Surama F; Rosenthal, Amauri; Rodrigo, Dolores; Klein, Günter; Martínez, Antonio

2015-01-01

This study investigates the effect of citral on growth and on the occurrence of sublethal damage in Listeria innocua Serovar 6a (CECT 910) and Listeria monocytogenes Serovar 4b (CECT 4032) cells that were exposed to citral as a natural antimicrobial agent. Two initial inoculum concentrations were considered in this investigation: 10(2) and 10(6) cfu/mL. Citral exhibited antilisterial activity against L. innocua and L. monocytogenes, and the observed effects were dependent on the concentration of citral present in the culture medium (0, 0.150 and 0.250 μL/mL) (p ≤ 0.05). L. innocua had a shorter lag phase than L. monocytogenes, and the two species had nearly identical maximum specific growth rates. These results indicate that L. innocua could be used as surrogate for L. monocytogenes when testing the effects of this antimicrobial. Significant differences in the lag phase and growth rate were observed between the small and large inoculum concentration (p ≤ 0.05). Citral-treated L. innocua and L. monocytogenes that were recovered on selective medium (i.e., TSA-YE-SC) had a shorter lag phase and a higher maximum specific growth rate than cells that were recovered on non-selective medium (i.e., TSA-YE) (p ≤ 0.05). This result suggests that damage occurs at sublethal concentrations of citral.

Solid-state fermentation of Mortierella isabellina for lipid production from soybean hull.

PubMed

Zhang, Jianguo; Hu, Bo

2012-02-01

Soybean hull, generated from soybean processing, is a lignocellulosic material with limited industrial applications and little market value. This research is exploring a new application of soybean hull to be converted to fungal lipids for biodiesel production through solid-state fermentation. Mortierella isabellina was selected as the oil producer because of its high lipid content at low C/N ratio. Several cultivation factors were investigated, including moisture content, inoculums size, fungal spore age, and nutrient supplements, in an attempt to enhance the lipid production of the solid-state fermentation process. The results showed that lipid production with the increase of the moisture content and the spore age, while decreased as the size of inoculums increased. Nutrients addition (KH₂PO₄ 1.2 mg and MgSO₄ 0.6 mg/g soybean hull) improved the lipid production. The total final lipid reached 47.9 mg lipid from 1 g soybean hull after the conversion, 3.3-fold higher than initial lipid reserve in the soybean hull. The fatty acid profile analysis indicated that fatty acid content consisted of 30.0% of total lipid, and 80.4% of total fatty acid was C16 and C18. Therefore, lipid production from soybean hull is a possible option to enable soybean hull as a new resource for biodiesel production and to enhance the overall oil production from soybeans.

Biological Pretreatment of Chicken Feather and Biogas Production from Total Broth.

PubMed

Patinvoh, Regina J; Feuk-Lagerstedt, Elisabeth; Lundin, Magnus; Sárvári Horváth, Ilona; Taherzadeh, Mohammad J

2016-12-01

Chicken feathers are available in large quantities around the world causing environmental challenges. The feathers are composed of keratin that is a recalcitrant protein and is hard to degrade. In this work, chicken feathers were aerobically pretreated for 2-8 days at total solid concentrations of 5, 10, and 20 % by Bacillus sp. C 4 , a bacterium that produces both α- and β-keratinases. Then, the liquid fraction (feather hydrolysate) as well as the total broth (liquid and solid fraction of pretreated feathers) was used as substrates for biogas production using anaerobic sludge or bacteria granules as inoculum. The biological pretreatment of feather waste was productive; about 75 % of feather was converted to soluble crude protein after 8 days of degradation at initial feather concentration of 5 %. Bacteria granules performed better during anaerobic digestion of untreated feathers, resulting in approximately two times more methane yield (i.e., 199 mlCH 4 /gVS compared to 105 mlCH 4 /gVS when sludge was used). Pretreatment improved methane yield by 292 and 105 % when sludge and granules were used on the hydrolysate. Bacteria granules worked effectively on the total broth, yielded 445 mlCH 4 /gVS methane, which is 124 % more than that obtained with the same type of inoculum from untreated feather.

Assessment of Cultivation Factors that Affect Biomass and Geraniol Production in Transgenic Tobacco Cell Suspension Cultures

PubMed Central

Vasilev, Nikolay; Schmitz, Christian; Grömping, Ulrike; Fischer, Rainer; Schillberg, Stefan

2014-01-01

A large-scale statistical experimental design was used to determine essential cultivation parameters that affect biomass accumulation and geraniol production in transgenic tobacco (Nicotiana tabacum cv. Samsun NN) cell suspension cultures. The carbohydrate source played a major role in determining the geraniol yield and factors such as filling volume, inoculum size and light were less important. Sucrose, filling volume and inoculum size had a positive effect on geraniol yield by boosting growth of plant cell cultures whereas illumination of the cultures stimulated the geraniol biosynthesis. We also found that the carbohydrates sucrose and mannitol showed polarizing effects on biomass and geraniol accumulation. Factors such as shaking frequency, the presence of conditioned medium and solubilizers had minor influence on both plant cell growth and geraniol content. When cells were cultivated under the screened conditions for all the investigated factors, the cultures produced ∼5.2 mg/l geraniol after 12 days of cultivation in shaking flasks which is comparable to the yield obtained in microbial expression systems. Our data suggest that industrial experimental designs based on orthogonal arrays are suitable for the selection of initial cultivation parameters prior to the essential medium optimization steps. Such designs are particularly beneficial in the early optimization steps when many factors must be screened, increasing the statistical power of the experiments without increasing the demand on time and resources. PMID:25117009

Assessment of cultivation factors that affect biomass and geraniol production in transgenic tobacco cell suspension cultures.

PubMed

Vasilev, Nikolay; Schmitz, Christian; Grömping, Ulrike; Fischer, Rainer; Schillberg, Stefan

2014-01-01

A large-scale statistical experimental design was used to determine essential cultivation parameters that affect biomass accumulation and geraniol production in transgenic tobacco (Nicotiana tabacum cv. Samsun NN) cell suspension cultures. The carbohydrate source played a major role in determining the geraniol yield and factors such as filling volume, inoculum size and light were less important. Sucrose, filling volume and inoculum size had a positive effect on geraniol yield by boosting growth of plant cell cultures whereas illumination of the cultures stimulated the geraniol biosynthesis. We also found that the carbohydrates sucrose and mannitol showed polarizing effects on biomass and geraniol accumulation. Factors such as shaking frequency, the presence of conditioned medium and solubilizers had minor influence on both plant cell growth and geraniol content. When cells were cultivated under the screened conditions for all the investigated factors, the cultures produced ∼ 5.2 mg/l geraniol after 12 days of cultivation in shaking flasks which is comparable to the yield obtained in microbial expression systems. Our data suggest that industrial experimental designs based on orthogonal arrays are suitable for the selection of initial cultivation parameters prior to the essential medium optimization steps. Such designs are particularly beneficial in the early optimization steps when many factors must be screened, increasing the statistical power of the experiments without increasing the demand on time and resources.

Biosorption of Cr(VI) in Aqueous Solution using Microorganisms: Comparison of the Use of Rhizopus oryzae, Bacillus firmus, and Trichoderma viride

NASA Astrophysics Data System (ADS)

Safitri, Anna; Mahardini, Putri; Prasetyawan, Sasangka; Roosdiana, Anna

2018-01-01

In this work, the study of biosorption of Cr(VI) from aqueous solution was conducted using Rhizopus oryzae, Bacillus firmus, and Trichoderma viride as microorganisms that can absorb Cr(VI). The research is focused on determination of optimum conditions including pH, the number of R. oryzae, B. firmus, and T. viride (inoculums), and initial concentrations of Cr(VI) used. Optimum pH was obtained at pH 5, 4.5 and 6, for biosorption of Cr(VI) with R. oryzae, B. firmus, and T. viride, respectively, in the capacity of 45.3%, 24.5%, and 90.3%. The highest amount of Cr(VI) adsorbed for biosorption with R. oryzae, B. firmus, and T. viride, were 55.4%, 18.5%, and 74.5%, respectively, using 6-mL inoculums. The equilibrium concentrations achieved for R. oryzae, B. firmus, and T. viride were 60 mg/mL, 40 mg/mL, and 40 mg/mL, with the amount of Cr(VI) adsorbed were 32.4%, 28.2%, and 89.3%, respectively. The adsorption capacity for R. oryzae, B. firmus, and T. viride were 45.3 mg/1×106 colonies, 36.2 mg/1×106 cells, and 77.8 mg/1×106 colonies, respectively. Overall, the biosorbents effectivity order in the biosorption process of Cr(VI) are T. viride > R. oryzae > B. firmus.

Application of Biofilm Covered Activated Carbon Particles as a Microbial Inoculum Delivery System for Enhanced Bioaugmentation of PCBs in Contaminated Sediment

DTIC Science & Technology

2013-09-01

after anaerobic digestion at thermophilic conditions (60- 70C). Application of biofilm covered activated carbon particles as a microbial inoculum...Sludge Thickener; Sludge = Sludge after anaerobic digestion at thermophilic conditions (60- 70C). C3. Microscopic evaluation of dechlorinating...associated enzymes are capable of opening the biphenyl ring structure and transform the molecule into a linear structure, this changed structure was not

Microbial detection method based on sensing molecular hydrogen

NASA Technical Reports Server (NTRS)

Wilkins, J. R.; Stoner, G. E.; Boykin, E. H.

1974-01-01

A simple method for detecting bacteria, based on the time of hydrogen evolution, was developed and tested against various members of the Enterobacteriaceae group. The test system consisted of (1) two electrodes, platinum and a reference electrode, (2) a buffer amplifier, and (3) a strip-chart recorder. Hydrogen evolution was measured by an increase in voltage in the negative (cathodic) direction. A linear relationship was established between inoculum size and the time hydrogen was detected (lag period). Lag times ranged from 1 h for 1 million cells/ml to 7 h for 1 cell/ml. For each 10-fold decrease in inoculum, length of the lag period increased 60 to 70 min. Based on the linear relationship between inoculum and lag period, these results indicate the potential application of the hydrogen-sensing method for rapidly detecting coliforms and other gas-producing microorganisms in a variety of clinical, food, and other samples.

Biochemical methane potential (BMP) of artichoke waste: the inoculum effect.

PubMed

Fabbri, Andrea; Serranti, Silvia; Bonifazi, Giuseppe

2014-03-01

The aim of this work was to investigate anaerobic digestibility of artichoke waste resulting from industrial transformation. A series of batch anaerobic digestion tests was performed in order to evaluate the biochemical methane potential of the matrix in respect of the process. A comparison of the different performances of the laboratory-scale reactors operating in mesophilic conditions and utilizing three different values of the inoculum/substrate ratio was carried out. The best performance was achieved with an inoculum/substrate ratio of 2. Artichoke-processing byproducts showed a classical organic waste decomposition behaviour: a fast start-up phase, an acclimation stage, and a final stabilization phase. Following this approach, artichoke waste reached chemical oxygen demand removal of about 90% in 40 days. The high methane yield (average 408.62 mL CH4 gvs (-1) voltatile solids), makes artichoke waste a good product to be utilized in anaerobic digestion plants for biogas production.

New Concepts in the Evaluation of Biodegradation/Persistence of Chemical Substances Using a Microbial Inoculum

PubMed Central

Thouand, Gérald; Durand, Marie-José; Maul, Armand; Gancet, Christian; Blok, Han

2011-01-01

The European REACH Regulation (Registration, Evaluation, Authorization of CHemical substances) implies, among other things, the evaluation of the biodegradability of chemical substances produced by industry. A large set of test methods is available including detailed information on the appropriate conditions for testing. However, the inoculum used for these tests constitutes a “black box.” If biodegradation is achievable from the growth of a small group of specific microbial species with the substance as the only carbon source, the result of the test depends largely on the cell density of this group at “time zero.” If these species are relatively rare in an inoculum that is normally used, the likelihood of inoculating a test with sufficient specific cells becomes a matter of probability. Normally this probability increases with total cell density and with the diversity of species in the inoculum. Furthermore the history of the inoculum, e.g., a possible pre-exposure to the test substance or similar substances will have a significant influence on the probability. A high probability can be expected for substances that are widely used and regularly released into the environment, whereas a low probability can be expected for new xenobiotic substances that have not yet been released into the environment. Be that as it may, once the inoculum sample contains sufficient specific degraders, the performance of the biodegradation will follow a typical S shaped growth curve which depends on the specific growth rate under laboratory conditions, the so called F/M ratio (ratio between food and biomass) and the more or less toxic recalcitrant, but possible, metabolites. Normally regulators require the evaluation of the growth curve using a simple approach such as half-time. Unfortunately probability and biodegradation half-time are very often confused. As the half-time values reflect laboratory conditions which are quite different from environmental conditions (after a substance is released), these values should not be used to quantify and predict environmental behavior. The probability value could be of much greater benefit for predictions under realistic conditions. The main issue in the evaluation of probability is that the result is not based on a single inoculum from an environmental sample, but on a variety of samples. These samples can be representative of regional or local areas, climate regions, water types, and history, e.g., pristine or polluted. The above concept has provided us with a new approach, namely “Probabio.” With this approach, persistence is not only regarded as a simple intrinsic property of a substance, but also as the capability of various environmental samples to degrade a substance under realistic exposure conditions and F/M ratio. PMID:21863143

Dry fermentation of agricultural residues

NASA Astrophysics Data System (ADS)

Jewell, W. J.; Chandler, J. A.; Dellorto, S.; Fanfoni, K. J.; Fast, S.; Jackson, D.; Kabrick, R. M.

1981-09-01

A dry fermentation process is discussed which converts agricultural residues to methane, using the residues in their as produced state. The process appears to simplify and enhance the possibilities for using crop residues as an energy source. The major process variables investigated include temperature, the amount and type of inoculum, buffer requirements, compaction, and pretreatment to control the initial available organic components that create pH problems. A pilot-scale reactor operation on corn stover at a temperature of 550 C, with 25 percent initial total solids, a seed-to-feed ratio of 2.5 percent, and a buffer-to-feed ratio of 8 percent achieved 33 percent total volatile solids destruction in 60 days. Volumetric biogas yields from this unit were greater than 1 vol/vol day for 12 days, and greater than 0.5 vol/vol day for 32 days, at a substrate density of 169 kg/m (3).

Reference gene selection for normalization of RT-qPCR gene expression data from Actinidia deliciosa leaves infected with Pseudomonas syringae pv. actinidiae

PubMed Central

Petriccione, Milena; Mastrobuoni, Francesco; Zampella, Luigi; Scortichini, Marco

2015-01-01

Normalization of data, by choosing the appropriate reference genes (RGs), is fundamental for obtaining reliable results in reverse transcription-quantitative PCR (RT-qPCR). In this study, we assessed Actinidia deliciosa leaves inoculated with two doses of Pseudomonas syringae pv. actinidiae during a period of 13 days for the expression profile of nine candidate RGs. Their expression stability was calculated using four algorithms: geNorm, NormFinder, BestKeeper and the deltaCt method. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and protein phosphatase 2A (PP2A) were the most stable genes, while β-tubulin and 7s-globulin were the less stable. Expression analysis of three target genes, chosen for RGs validation, encoding the reactive oxygen species scavenging enzymes ascorbate peroxidase (APX), superoxide dismutase (SOD) and catalase (CAT) indicated that a combination of stable RGs, such as GAPDH and PP2A, can lead to an accurate quantification of the expression levels of such target genes. The APX level varied during the experiment time course and according to the inoculum doses, whereas both SOD and CAT resulted down-regulated during the first four days, and up-regulated afterwards, irrespective of inoculum dose. These results can be useful for better elucidating the molecular interaction in the A. deliciosa/P. s. pv. actinidiae pathosystem and for RGs selection in bacteria-plant pathosystems. PMID:26581656

Effect of incubation time, inoculum size, temperature, pasteurization time, goat milk powder and whey powder on ACE inhibitory activity in fermented milk by L. plantarum LP69.

PubMed

Shu, Guowei; Yang, Hui; Chen, He; Zhang, Qiuhong; Tian, Yue

2015-01-01

Angiotensin I converting enzyme (ACE) plays an important physiological role in regulating hypertension. Lactic acid bacteria are known to produce ACE inhibitory peptides which can lower hypertension during fermentation. The effect of incubation time (0~36 h), inoculum size (3, 4, 5, 6 and 7%, v/v), temperature (25, 30, 35, 40 and 45°C), sterilization time (5, 10, 15, 20 and 25 min), concentration of goat milk powder (8, 10, 12, 14 and 16%, w/v) and whey powder (0.5, 0.6, 0.7, 0.8 and 0.9%, w/v) on ACE inhibitory peptides fermented from goat milk by Lactobacillus plantarum LP69 was investigated using single factor experiment. The optimal incubation time, inoculum size, temperature, pasteurization time, goat milk powder and whey powder in fermented milk by L. plantarum LP69 was 14 h, 3.0%, 35°C, 20 min, 14% and 0.70% for ACE inhibitory activity and 22 h, 3.0%, 40°C, 25 min, 16% and 0.60% for viable cell counts, respectively. The incubation time, inoculum size, temperature, pasteurization time, goat milk powder and whey powder had a significant influence on ACE inhibitory activity in fermented milk by Lactobacillus plantarum LP69, the results are beneficial for further screening of main factors by using fractional factorial designs.

Impact of the start-up process on the microbial communities in biocathodes for electrosynthesis.

PubMed

Mateos, Raúl; Sotres, Ana; Alonso, Raúl M; Escapa, Adrián; Morán, Antonio

2018-06-01

This study seeks to understand how the bacterial communities that develop on biocathodes are influenced by inocula diversity and electrode potential during start-up. Two different inocula are used: one from a highly diverse environment (river mud) and the other from a low diverse milieu (anaerobic digestion). In addition, both inocula were subjected to two different polarising voltages: oxidative (+0.2 V vs. Ag/AgCl) and reductive (-0.8 V vs. Ag/AgCl). Bacterial communities were analysed by means of high throughput sequencing. Possible syntrophic interactions and competitions between archaea and eubacteria were described together with a discussion of their potential role in product formation and current production. The results confirmed that reductive potentials lead to an inconsistent start-up procedure regardless of the inoculum used. However, imposing oxidative potentials help to quickly develop an electroactive biofilm ready to withstand reductive potentials (i.e. biocathodic operation). The microbial structure that finally developed on them was highly dependent on the raw community present in the inoculum. Using a non-specialised inoculum resulted in a highly specialised biofilm, which was accompanied by an improved performance in terms of consumed current and product generation. Interestingly, a much more specialised inoculum promoted a rediversification in the biofilm, with a lower general cell performance. Copyright © 2018 Elsevier B.V. All rights reserved.

Biogas production from oil palm empty fruit bunches of post mushroom cultivation media

NASA Astrophysics Data System (ADS)

Purnomo, Agus; Suprihatin; Romli, M.; Hasanudin, Udin

2018-03-01

The Empty fruit bunches are one of the palm oil industry wastes, which can be used for mushroom cultivation. Post-cultivation of mushroom from former EFB-mushroom media (EFBMM) has the potential to be processed into biogas. The purpose of this research was to examine optimum co-digestion conditions for biogas production of EFBMM.The research was carried out in an anaerobic digester with three different conditions - dry fermentation (Water content (WC)/Total Solid (TS) ratio 1.5 - 3.5), semi-wet fermentation (WC/TS ratio = 4.0 - 5.7) and wet fermentation (WC/TS ratio> 9.0) conditions. Digester of capacity 50L was used. Fermentation was done using 20% cow feces as inoculum which then added with circulation system for 70 days. The results showed that optimum biogas production were produced in semi-wet fermentation conditions (WC/TS ratio = 4). It was produced 37.462 liters (2.420 liters CH4/Kg Volatile Solid (VS)) of biogas with methane contain about 26.231%. Total volume of inoculum during process was 19.6 liters (1: 4 w/v) with absorbed TS inoculum ratio, TS/I = 0.4 (1:2.5 w/v). The result of research also showed that biogas which was produced from control about 2.865 liters (0.041 liters CH4/KgVS), with TS absorbed inoculum ratio, TS/I = 0.5 (1: 5w/v).

Physiological responses to acid stress by Saccharomyces cerevisiae when applying high initial cell density

PubMed Central

2016-01-01

High initial cell density is used to increase volumetric productivity and shorten production time in lignocellulosic hydrolysate fermentation. Comparison of physiological parameters in high initial cell density cultivation of Saccharomyces cerevisiae in the presence of acetic, formic, levulinic and cinnamic acids demonstrated general and acid-specific responses of cells. All the acids studied impaired growth and inhibited glycolytic flux, and caused oxidative stress and accumulation of trehalose. However, trehalose may play a role other than protecting yeast cells from acid-induced oxidative stress. Unlike the other acids, cinnamic acid did not cause depletion of cellular ATP, but abolished the growth of yeast on ethanol. Compared with low initial cell density, increasing initial cell density reduced the lag phase and improved the bioconversion yield of cinnamic acid during acid adaptation. In addition, yeast cells were able to grow at elevated concentrations of acid, probable due to the increase in phenotypic cell-to-cell heterogeneity in large inoculum size. Furthermore, the specific growth rate and the specific rates of glucose consumption and metabolite production were significantly lower than at low initial cell density, which was a result of the accumulation of a large fraction of cells that persisted in a viable but non-proliferating state. PMID:27620460

Evolution of infection in mice inoculated by the oral route with different developmental forms of Trypanosoma cruzi I and II.

PubMed

Dias, Greicy Brisa Malaquias; Gruendling, Ana Paula; Araújo, Silvana Marques; Gomes, Mônica Lúcia; Toledo, Max Jean de Ornelas

2013-11-01

Oral infection has become the most important transmission mechanism of Chagas disease in Brazil. For this study, the development of Trypanosoma cruzi infection in mice, induced by the oral and intraperitoneal (IP) routes, was compared. Four groups of Swiss mice were used to evaluate the influence of parasite genetics, number of parasites, inoculation volume and developmental stages on the development of the orally induced infection: 1 - blood trypomastigotes (BT) via oral; 2 - BT via IP; 3 - culture metacyclic trypomastigotes (MT) via oral; and 4 - culture MT via IP. Animals inoculated orally showed levels of parasitemia, as well as infectivity and mortality rates, lower than animals inoculated via IP, regardless of DTU (discrete typing unit) and inoculum. Animals infected with TcII showed higher levels of these parameters than did animals infected with TcI. The larger volume of inoculum showed a greater capacity to cause an infection when administered via the oral route. BT infection was more virulent than culture MT infection for both routes (oral and IP). However, mice inoculated orally with BT showed lower levels than via IP, while mice inoculated orally with culture MT showed similar levels of infection to those inoculated via IP. Mice inoculated with culture MT showed more histopathological changes than those inoculated with BT, regardless of the inoculation route. These results indicate that this alternative experimental model is useful for evaluating infection by T. cruzi isolates with subpatent parasitemia and low virulence, such as those belonging to the TcI and TcIV DTUs, which are prevalent in outbreaks of orally transmitted Chagas disease. Copyright © 2013 Elsevier Inc. All rights reserved.

Efficacy of a Blend of Sulfuric Acid and Sodium Sulfate against Shiga Toxin-Producing Escherichia coli, Salmonella, and Nonpathogenic Escherichia coli Biotype I on Inoculated Prerigor Beef Surface Tissue.

PubMed

Scott-Bullard, Britteny R; Geornaras, Ifigenia; Delmore, Robert J; Woerner, Dale R; Reagan, James O; Morgan, J Bred; Belk, Keith E

2017-12-01

A study was conducted to investigate the efficacy of a sulfuric acid-sodium sulfate blend (SSS) against Escherichia coli O157:H7, non-O157 Shiga toxin-producing E. coli (STEC), Salmonella, and nonpathogenic E. coli biotype I on prerigor beef surface tissue. The suitability of using the nonpathogenic E. coli as a surrogate for in-plant validation studies was also determined by comparing the data obtained for the nonpathogenic inoculum with those for the pathogenic inocula. Prerigor beef tissue samples (10 by 10 cm) were inoculated (ca. 6 log CFU/cm 2 ) on the adipose side in a laboratory-scale spray cabinet with multistrain mixtures of E. coli O157:H7 (5 strains), non-O157 STEC (12 strains), Salmonella (6 strains), or E. coli biotype I (5 strains). Treatment parameters evaluated were two SSS pH values (1.5 and 1.0) and two spray application pressures (13 and 22 lb/in 2 ). Untreated inoculated beef tissue samples served as controls for initial bacterial populations. Overall, the SSS treatments lowered inoculated (6.1 to 6.4 log CFU/cm 2 ) bacterial populations by 0.6 to 1.5 log CFU/cm 2 (P < 0.05), depending on inoculum type and recovery medium. There were no main effects (P ≥ 0.05) of solution pH or spray application pressure when SSS was applied to samples inoculated with any of the tested E. coli inocula; however, solution pH did have a significant effect (P < 0.05) when SSS was applied to samples inoculated with Salmonella. Results indicated that the response of the nonpathogenic E. coli inoculum to the SSS treatments was similar (P ≥ 0.05) to that of the pathogenic inocula tested, making the E. coli biotype I strains viable surrogate organisms for in-plant validation of SSS efficacy on beef. The application of SSS at the tested parameters to prerigor beef surface tissue may be an effective intervention for controlling pathogens in a commercial beef harvest process.

R software package based statistical optimization of process components to simultaneously enhance the bacterial growth, laccase production and textile dye decolorization with cytotoxicity study

PubMed Central

Dudhagara, Pravin; Tank, Shantilal

2018-01-01

The thermophilic bacterium, Bacillus licheniformis U1 is used for the optimization of bacterial growth (R1), laccase production (R2) and synthetic disperse blue DBR textile dye decolorization (R3) in the present study. Preliminary optimization has been performed by one variable at time (OVAT) approach using four media components viz., dye concentration, copper sulphate concentration, pH, and inoculum size. Based on OVAT result further statistical optimization of R1, R2 and R3 performed by Box–Behnken design (BBD) using response surface methodology (RSM) in R software with R Commander package. The total 29 experimental runs conducted in the experimental design study towards the construction of a quadratic model. The model indicated that dye concentration 110 ppm, copper sulphate 0.2 mM, pH 7.5 and inoculum size 6% v/v were found to be optimum to maximize the laccase production and bacterial growth. Whereas, maximum dye decolorization achieved in media containing dye concentration 110 ppm, copper sulphate 0.6 mM, pH 6 and inoculum size 6% v/v. R package predicted R2 of R1, R2 and R3 were 0.9917, 0.9831 and 0.9703 respectively; likened to Design-Expert (Stat-Ease) (DOE) predicted R2 of R1, R2, and R3 were 0.9893, 0.9822 and 0.8442 respectively. The values obtained by R software were more precise, reliable and reproducible, compared to the DOE model. The laccase production was 1.80 fold increased, and 2.24 fold enhancement in dye decolorization was achieved using optimized medium than initial experiments. Moreover, the laccase-treated sample demonstrated the less cytotoxic effect on L132 and MCF-7 cell lines compared to untreated sample using MTT assay. Higher cell viability and lower cytotoxicity observed in a laccase-treated sample suggest the impending application of bacterial laccase in the reduction of toxicity of dye to design rapid biodegradation process. PMID:29718934

Nutrients Can Enhance the Abundance and Expression of Alkane Hydroxylase CYP153 Gene in the Rhizosphere of Ryegrass Planted in Hydrocarbon-Polluted Soil

PubMed Central

Arslan, Muhammad; Afzal, Muhammad; Amin, Imran; Iqbal, Samina; Khan, Qaiser M.

2014-01-01

Plant-bacteria partnership is a promising strategy for the remediation of soil and water polluted with hydrocarbons. However, the limitation of major nutrients (N, P and K) in soil affects the survival and metabolic activity of plant associated bacteria. The objective of this study was to explore the effects of nutrients on survival and metabolic activity of an alkane degrading rhizo-bacterium. Annual ryegrass (Lolium multiflorum) was grown in diesel-contaminated soil and inoculated with an alkane degrading bacterium, Pantoea sp. strain BTRH79, in greenhouse experiments. Two levels of nutrients were applied and plant growth, hydrocarbon removal, and gene abundance and expression were determined after 100 days of sowing of ryegrass. Results obtained from these experiments showed that the bacterial inoculation improved plant growth and hydrocarbon degradation and these were further enhanced by nutrients application. Maximum plant biomass production and hydrocarbon mineralization was observed by the combined use of inoculum and higher level of nutrients. The presence of nutrients in soil enhanced the colonization and metabolic activity of the inoculated bacterium in the rhizosphere. The abundance and expression of CYP153 gene in the rhizosphere of ryegrass was found to be directly associated with the level of applied nutrients. Enhanced hydrocarbon degradation was associated with the population of the inoculum bacterium, the abundance and expression of CYP153 gene in the rhizosphere of ryegrass. It is thus concluded that the combination between vegetation, inoculation with pollutant-degrading bacteria and nutrients amendment was an efficient approach to reduce hydrocarbon contamination. PMID:25360680

Effect of storage conditions in the response of Listeria monocytogenes in a fresh purple vegetable smoothie compared with an acidified TSB medium.

PubMed

González-Tejedor, Gerardo A; Garre, Alberto; Esnoz, A; Artés-Hernández, F; Fernández, P S

2018-06-01

In this study, growth and/or inactivation of Listeria monocytogenes 4032 at different inoculum levels in a vegetable smoothie with purple colour, (previously heat stabilised at 95 °C for 3 min) was evaluated. Growth/inactivation was compared with acidified TSB medium at the same pH level with HCl. Samples were stored at different temperatures (5, 10, 15 and 25 °C). All the smoothies stored at 15 and 25 °C showed growth up to 7.5-8.0 log CFU/mL and at 10 °C growth was only observed at the highest inoculum level. Growth was only observed at 25 °C in acidified TSB. In the case of the smoothies inoculated and stored at 5 °C, L. monocytogenes was not able to grow but survived for a long period of time, whereas at the lower inocula at 10 °C they presented a slow inactivation for an extended time. Acidified TSB inoculated and stored showed inactivation at 5, 10 and 15 °C. Best inactivation modelling alternatives are proposed. The differences between the smoothie and TSB medium about growth or survival in this study, even at relatively low pH values, were due to the favorable nutritional composition of the smoothie compared to a laboratory medium. Results in this study can allow to design safe conditions for smoothie production. Copyright © 2017 Elsevier Ltd. All rights reserved.

Ecological patterns of seed microbiome diversity, transmission, and assembly.

PubMed

Shade, Ashley; Jacques, Marie-Agnès; Barret, Matthieu

2017-06-01

Seeds are involved in the transmission of microorganisms from one plant generation to another and consequently act as the initial inoculum for the plant microbiota. The purpose of this mini-review is to provide an overview of current knowledge on the diversity, structure and role of the seed microbiota. The relative importance of the mode of transmission (vertical vs horizontal) of the microbial entities composing the seed microbiota as well as the potential connections existing between seed and other plant habitats such as the anthosphere and the spermosphere is discussed. Finally the governing processes (niche vs neutral) involved in the assembly and the dynamics of the seed microbiota are examined. Copyright © 2017. Published by Elsevier Ltd.

Bacillus licheniformis BT5.9 Isolated from Changar Hot Spring, Malang, Indonesia, as a Potential Producer of Thermostable α-amylase

PubMed Central

Ibrahim, Darah; Zhu, Han Li; Yusof, Nuraqilah; Isnaeni; Hong, Lim Sheh

2013-01-01

A total of 34 bacterial isolates were obtained from soil samples collected from Changar Hot Spring, Malang, Indonesia. Of these, 13 isolates produced a zone of hydrolysis in starch-nutrient agar medium and generated various amylases in liquid medium. One isolate was selected as the best amylase producer and was identified as Bacillus licheniformis BT5.9. The improvement of culture conditions (initial medium pH of 5.0, cultivation temperature of 50°C, agitation speed of 100 rpm and inoculum size of 1.7 × 109 cells/ml) provided the highest amylase production (0.327 U/ml). PMID:24575243

Probiotic effect on calves infected with Salmonella Dublin: haematological parameters and serum biochemical profile.

PubMed

Soto, L P; Astesana, D M; Zbrun, M V; Blajman, J E; Salvetti, N R; Berisvil, A P; Rosmini, M R; Signorini, M L; Frizzo, L S

2016-02-01

The aim of this study was to evaluate the effect of a probiotic/lactose inoculum on haematological and immunological parameters and renal and hepatic biochemical profiles before and during a Salmonella Dublin DSPV 595T challenge in young calves. Twenty eight calves, divided into a control and probiotic group were used. The probiotic group was supplemented with 100 g lactose/calf/d and 10 10 cfu/calf/d of each strain of a probiotic inoculum composed of Lactobacillus casei DSPV318T, Lactobacillus salivarius DSPV315T and Pediococcus acidilactici DSPV006T throughout the experiment. The pathogen was administered on day 11 of the experiment, at an oral dose of 10 9 cfu/animal (LD 50 ). Aspartate aminotransferase (AST), gamma glutamyl transpeptidase (GGT), urea, red blood cells, haemoglobin, haematocrit, mean cell haemoglobin (MCH), mean corpuscular volume, mean corpuscular haemoglobin concentration (MCHC), white blood cells, lymphocytes, neutrophils, band neutrophils, monocytes, eosinophils, basophils and the neutrophils/lymphocytes ratio were measured on days 1, 10, 20 and 27 of the experiment. In addition, animals were necropsied to evaluate immunoglobulin A (IgA) production in the jejunal mucosa. The most significant differences caused by the administration of the inoculum/lactose were found during the acute phase of Salmonella challenge (9 days after challenge), when a difference between groups in neutrophils/lymphocytes ratio were detected. These results suggest that the probiotic/lactose inoculum administration increases the calf's ability to respond to the disease increasing the systemic immune response specific. No differences were found in haemoglobin, haematocrit, MCH, MCHC, AST, urea, GGT, band neutrophils, eosinophils, monocytes and IgA in the jejunum between the two groups of calves under the experimental conditions of this study. Further studies must be conducted to evaluate different probiotic/pathogens doses and different sampling times, to achieve a greater understanding of the effects of this inoculum on intestinal infections in young calves and of its mechanism of action.

Mosquito cell-derived West Nile virus replicon particles mimic arbovirus inoculum and have reduced spread in mice.

PubMed

Boylan, Brendan T; Moreira, Fernando R; Carlson, Tim W; Bernard, Kristen A

2017-02-01

Half of the human population is at risk of infection by an arthropod-borne virus. Many of these arboviruses, such as West Nile, dengue, and Zika viruses, infect humans by way of a bite from an infected mosquito. This infectious inoculum is insect cell-derived giving the virus particles distinct qualities not present in secondary infectious virus particles produced by infected vertebrate host cells. The insect cell-derived particles differ in the glycosylation of virus structural proteins and the lipid content of the envelope, as well as their induction of cytokines. Thus, in order to accurately mimic the inoculum delivered by arthropods, arboviruses should be derived from arthropod cells. Previous studies have packaged replicon genome in mammalian cells to produce replicon particles, which undergo only one round of infection, but no studies exist packaging replicon particles in mosquito cells. Here we optimized the packaging of West Nile virus replicon genome in mosquito cells and produced replicon particles at high concentration, allowing us to mimic mosquito cell-derived viral inoculum. These particles were mature with similar genome equivalents-to-infectious units as full-length West Nile virus. We then compared the mosquito cell-derived particles to mammalian cell-derived particles in mice. Both replicon particles infected skin at the inoculation site and the draining lymph node by 3 hours post-inoculation. The mammalian cell-derived replicon particles spread from the site of inoculation to the spleen and contralateral lymph nodes significantly more than the particles derived from mosquito cells. This in vivo difference in spread of West Nile replicons in the inoculum demonstrates the importance of using arthropod cell-derived particles to model early events in arboviral infection and highlights the value of these novel arthropod cell-derived replicon particles for studying the earliest virus-host interactions for arboviruses.

The In Vitro Mass-Produced Model Mycorrhizal Fungus, Rhizophagus irregularis, Significantly Increases Yields of the Globally Important Food Security Crop Cassava

PubMed Central

Ceballos, Isabel; Ruiz, Michael; Fernández, Cristhian; Peña, Ricardo

2013-01-01

The arbuscular mycorrhizal symbiosis is formed between arbuscular mycorrhizal fungi (AMF) and plant roots. The fungi provide the plant with inorganic phosphate (P). The symbiosis can result in increased plant growth. Although most global food crops naturally form this symbiosis, very few studies have shown that their practical application can lead to large-scale increases in food production. Application of AMF to crops in the tropics is potentially effective for improving yields. However, a main problem of using AMF on a large-scale is producing cheap inoculum in a clean sterile carrier and sufficiently concentrated to cheaply transport. Recently, mass-produced in vitro inoculum of the model mycorrhizal fungus Rhizophagus irregularis became available, potentially making its use viable in tropical agriculture. One of the most globally important food plants in the tropics is cassava. We evaluated the effect of in vitro mass-produced R. irregularis inoculum on the yield of cassava crops at two locations in Colombia. A significant effect of R. irregularis inoculation on yield occurred at both sites. At one site, yield increases were observed irrespective of P fertilization. At the other site, inoculation with AMF and 50% of the normally applied P gave the highest yield. Despite that AMF inoculation resulted in greater food production, economic analyses revealed that AMF inoculation did not give greater return on investment than with conventional cultivation. However, the amount of AMF inoculum used was double the recommended dose and was calculated with European, not Colombian, inoculum prices. R. irregularis can also be manipulated genetically in vitro, leading to improved plant growth. We conclude that application of in vitro R. irregularis is currently a way of increasing cassava yields, that there is a strong potential for it to be economically profitable and that there is enormous potential to improve this efficiency further in the future. PMID:23950975

In Vitro Pharmacodynamics of AZD5206 against Staphylococcus aureus

PubMed Central

Chang, Kai-Tai; Yang, Zhen; Newman, Joseph; Hu, Ming

2013-01-01

AZD5206 is a novel antimicrobial agent with potent in vitro activity against Staphylococcus aureus. We evaluated the in vitro pharmacodynamics of AZD5206 against a standard wild-type methicillin-susceptible strain (ATCC 29213) and a clinical strain of methicillin-resistant S. aureus (SA62). Overall, bacterial killing against a low baseline inoculum was more remarkable. Low dosing exposures and/or high baseline inoculum resulted in early reduction in bacterial burden, followed by regrowth and selective amplification of the resistant population. PMID:23229481

A Framework for Optimizing Phytosanitary Thresholds in Seed Systems.

PubMed

Choudhury, Robin Alan; Garrett, Karen A; Klosterman, Steven J; Subbarao, Krishna V; McRoberts, Neil

2017-10-01

Seedborne pathogens and pests limit production in many agricultural systems. Quarantine programs help prevent the introduction of exotic pathogens into a country, but few regulations directly apply to reducing the reintroduction and spread of endemic pathogens. Use of phytosanitary thresholds helps limit the movement of pathogen inoculum through seed, but the costs associated with rejected seed lots can be prohibitive for voluntary implementation of phytosanitary thresholds. In this paper, we outline a framework to optimize thresholds for seedborne pathogens, balancing the cost of rejected seed lots and benefit of reduced inoculum levels. The method requires relatively small amounts of data, and the accuracy and robustness of the analysis improves over time as data accumulate from seed testing. We demonstrate the method first and illustrate it with a case study of seedborne oospores of Peronospora effusa, the causal agent of spinach downy mildew. A seed lot threshold of 0.23 oospores per seed could reduce the overall number of oospores entering the production system by 90% while removing 8% of seed lots destined for distribution. Alternative mitigation strategies may result in lower economic losses to seed producers, but have uncertain efficacy. We discuss future challenges and prospects for implementing this approach.

Recovery of failed solid-state anaerobic digesters.

PubMed

Yang, Liangcheng; Ge, Xumeng; Li, Yebo

2016-08-01

This study examined the performance of three methods for recovering failed solid-state anaerobic digesters. The 9-L digesters, which were fed with corn stover, failed at a feedstock/inoculum (F/I) ratio of 10 with negligible methane yields. To recover the systems, inoculum was added to bring the F/I ratio to 4. Inoculum was either added to the top of a failed digester, injected into it, or well-mixed with the existing feedstock. Digesters using top-addition and injection methods quickly resumed and achieved peak yields in 10days, while digesters using well-mixed method recovered slowly but showed 50% higher peak yields. Overall, these methods recovered 30-40% methane from failed digesters. The well-mixed method showed the highest methane yield, followed by the injection and top-addition methods. Recovered digesters outperformed digesters had a constant F/I ratio of 4. Slow mass transfer and slow growth of microbes were believed to be the major limiting factors for recovery. Copyright © 2016 Elsevier Ltd. All rights reserved.

Forest farming of shiitake mushrooms: an integrated evaluation of management practices.

PubMed

Bruhn, J N; Mihail, J D; Pickens, J B

2009-12-01

Two outdoor shiitake (Lentinula edodes) cultivation experiments, established in Missouri USA in 1999 and 2000, produced mushrooms in 2000-2005. We examined shiitake production in response to substrate species, inoculum form, inoculum strain, and inoculation timing, using total mushroom weight per log as the primary response variable with log characteristics as covariates. The significantly greater mushroom weight produced by sugar maple logs compared with white or northern red oak was attributable to the higher proportion of undiscolored wood volume in the maple logs, rather than to bark thickness or log diameter. The "wide temperature range" shiitake strain produced significantly greater yield compared with the "warm" or "cold" weather strains. Both the wide-range and warm-weather strains were stimulated to fruit by significant rain events, while the cold-weather strain was responsive to temperature. Inoculation with sawdust spawn gave significantly greater yield than colonized wooden dowels or pre-packaged "thimble" plug inoculum. The second and third full years following inoculation were the most productive.

Favourable culture conditions for mycelial growth of Hydnum repandum, a medicinal mushroom.

PubMed

Peksen, Aysun; Kibar, Beyhan; Yakupoglu, Gokcen

2013-01-01

In this study, factors such as pH, temperature, carbon and nitrogen sources that affect mycelial growth of Hydnum repandum, a medicinal mushroom, were investigated. Different inoculum media for vegetative inoculum production were also examined. The best suitable pH for mycelial growth was found to be 5.5. Among constant temperatures, the best mycelial growth was obtained at 20 and 25°C. The mycelial growth drastically decreased at 15°C, and no mycelia were obtained at 30°C. Glucose and mannitol were found to be the most suitable carbon sources. Ca(NO3)2 as a nitrogen source gave the best results for mycelial growth. The poorest mycelial growth was noted in sucrose and xylose as carbon sources and in NH4NO3 and (NH4)2HPO4 as nitrogen sources. Peat and peat: vermiculite mixtures (1:4, 1:6, 1:8 and 1:10, v:v) were the best media to use in producing the vegetative inoculum of H. repandum.

Inoculum production and long-term conservation methods for cucurbits and tomato powdery mildews.

PubMed

Bardin, Marc; Suliman, Muna E; Sage-Palloix, Anne-Marie; Mohamed, Youssif F; Nicot, Philippe C

2007-06-01

The behaviour of cucurbit powdery mildews (Podosphaera xanthii and Golovinomyces cichoracearum) and tomato powdery mildew (Oidium neolycopersici) infesting detached cotyledons of Lagenaria leucantha cv. 'Minibottle' was studied in order to develop an easy culture method for pure inoculum production. High spore production was found with a combination of mannitol (0.1 m), sucrose (0.02 m) and agar (8 gl(-1)) in the cotyledon survival medium. Sporulation on cotyledons and viability of conidia were affected by the age of culture for the three species of powdery mildew tested. The age of cotyledons had also an impact of the spore production. This method was used to produce large amounts of inoculum for P. xanthii, G. cichoracearum and O. neolycopersici and enable the development of other species of powdery mildew like Leveillula taurica. Freezing conidia in liquid nitrogen enabled the long-term conservation of P. xanthii without any loss of virulence. The same method was unsuccessful with G. cichoracearum, and L. taurica and partly successful with O. neolycopersici.

[Virulence of Sporothrix globosa in murine models].

PubMed

Cruz Choappa, Rodrigo; Pérez Gaete, Salomón; Rodríguez Badilla, Valentina; Vieille Oyarzo, Peggy; Opazo Sanchez, Héctor

The sporothricosis disease is an infection caused by species included in Sporothrix schenkii complex. Verify the virulence of a strain of S. globosa using two different concentrations of inoculum by intraperitoneally and subcutaneously, into a mouse model. Nonrandomized pilot study, in murine inoculated with a strain of S. globosa (CBS 14.076M) by intraperitoneally and subcutaneously with inoculum concentrations of 0.5 and 4 McFarland. For this purpose 18 rodents CF-1 (ISP, Santiago, Chile) were used. The studied strain did not induce illness or injury on animals, they all survived and neither the tissue culture nor the histopathological analysis showed fungal growth or suggestive infection by organ abnormalities. The S. globosa strain did not present any virulence enough to cause disease at 0.5 and 4.0 McFarland concentration inoculum when inoculated in both intraperitoneally and subcutaneously, in murine models. Copyright © 2016 Asociación Argentina de Microbiología. Publicado por Elsevier España, S.L.U. All rights reserved.

Hybrid solid anaerobic digestion batch: biomethane production and mass recovery from the organic fraction of solid waste.

PubMed

Di Maria, Francesco; Gigliotti, Giovanni; Sordi, Alessio; Micale, Caterina; Zadra, Claudia; Massaccesi, Luisa

2013-08-01

An experimental apparatus was constructed to perform hybrid solid anaerobic digestion batch processing of the organic fraction of municipal solid waste. The preliminary process was carried out with a high total solids concentration of about 33% w w(-1) and with an initial organic load of about 340 kg VS kg(-1). The fresh organic fraction to inoculum ratio used to enhance the anaerobic process start-up was 0.910 kg VS kg VS(-1). The process was conducted by spreading the percolate on top of the mixture. The percolate was stored in a separate section of the apparatus with a mean hydraulic retention time of about 1 day. During the process, acetate, butyrate and propionate in the percolate reached concentrations ranging from 3000 to 11 000 mg L(-1). In spite of these high concentrations, the biomethane produced from both the solid and the percolate was quite high, at about 210 NL kg VS(-1). The digestate obtained at the end of the run showed rather good features for being classified as an organic fertilizer according to Italian law. However, a residual phytotoxicity level was detected by a standardized test showing a germination index of about 50%.

A biologically inspired variable-pH strategy for enhancing short-chain fatty acids (SCFAs) accumulation in maize straw fermentation.

PubMed

Meng, Yao; Mumme, Jan; Xu, Heng; Wang, Kaijun

2016-02-01

This study investigates the feasibility of varying the pH to enhance the accumulation of short-chain fatty acids (SCFAs) in the in vitro fermentation of maize straw. The corresponding hydrolysis rate and the net SCFA yield increased as inoculum ratio (VSinoculum/VSsubstrate) increased from 0.09 to 0.79. The pH were maintained at 5.3, 5.8, 6.3, 6.8, 7.3, and 7.8, respectively. A neutral pH of approximately 6.8 was optimal for hydrolysis. The net SCFA yield decreased by 34.9% for a pH of less than 5.8, but remained constant at approximately 721±5mg/gvs for a pH between 5.8 and 7.8. In addition, results were obtained for variable and constant pH levels at initial substrate concentrations of 10, 30 and 50g/L. A variable pH increased the net SCFA yield by 23.6%, 29.0%, and 36.6% for concentrations of 10, 30 and 50g/L. Therefore, a variable pH enhanced SCFA accumulation in maize straw fermentation. Copyright © 2015 Elsevier Ltd. All rights reserved.

A comparative study of different tests for biodegradability enhancement determination during AOP treatment of recalcitrant toxic aqueous solutions.

PubMed

Ballesteros Martín, M M; Casas López, J L; Oller, I; Malato, S; Sánchez Pérez, J A

2010-09-01

Four biodegradability tests (Pseudomonas putida bioassay, Zahn-Wellens test, BOD5/COD ratio and respirometry assay) have been used to determine the biodegradability enhancement during the treatment of wastewater containing 200 mg L(-1) of dissolved organic carbon (DOC) of a five commercial pesticides mixture (Vydate, Metomur, Couraze, Ditumur and Scala) by an advanced oxidation process (AOP). A comparative study was carried out taking into account repeatability and precision of each biodegradability test. Solar photo-Fenton was the AOP selected for pesticide degradation up to three levels of mineralization: 20%, 40% and 60% of initial DOC. Intra- and interday precisions were evaluated conducting each biodegradability test by triplicate and they were applied three times on different dates over a period of three months. Fisher's least significant difference method was applied to the means, P. putida and Zahn-Wellens tests giving higher repeatability and precision. The P. putida test requires a shorter time to obtain reliable results using a standardized inoculum and constitutes a worthwhile alternative to estimate biodegradability in contrast to other less accurate or more time consuming methods. Copyright (c) 2010 Elsevier Inc. All rights reserved.

Molecular evaluation of microalgal communities in full-scale waste stabilisation ponds.

PubMed

Eland, Lucy E; Davenport, Russell J; Santos, Andre Bezerra Dos; Mota Filho, Cesar R

2018-02-22

Waste stabilisation ponds (WSPs) are widely used across the world as a passive wastewater treatment for domestic wastewaters, but little is known about their ecology, especially their phototrophic communities. This study uses molecular methods and flow cytometry to assess the cyanobacterial and eukaryotic communities longitudinally throughout two systems, one treating domestic wastewater and the other mixed industrial/domestic wastewaters. More variation was seen between the systems than between different stages in the treatment processes for both eukaryotic and cyanobacterial communities. Chlorella species and Planktophrix cyanobacteria dominated both treatment systems. Arthrospira cyanobacteria were detected only in the industrial/domestic system. The balance between non-photosynthetic and photosynthetic organisms is rarely considered, though both play vital roles in WSP functioning. Flow cytometry showed that the facultative and first maturation pond in the industrial system contained a lower proportion of photosynthetic organisms compared to the domestic system. This is reflected in the species richness data and low dissolved oxygen levels detected. All data indicated that both systems are significantly different from one another and that variation longitudinally throughout the systems is lower. A more systematic study is needed to determine if it is the wastewater source rather than the initial inoculum that drives community composition.

Analysis of Biogeochemistry of Acid-Mine Drainage at Rowe, Massachusetts

NASA Astrophysics Data System (ADS)

Ahlfeld, D. P.; Yuretich, R.; Ergas, S.; Nusslein, K.; Feldman, A.

2003-12-01

Acid waters rich in iron and sulfate can support a wide variety of microorganisms that catalyze the oxidation-reduction reactions of these bioactive elements, exemplified by acid-mine drainage (AMD). In order to study the biogeochemistry of natural attenuation a field site has been established at Davis Mine, an abandoned pyrite mine in rural Rowe Massachusetts. This site is of particular interest because of the apparent dynamic equilibrium that has restricted the extent of the AMD in this area since the mine was closed nearly 100 years ago. Initial evidence suggests that sulfate reduction is occurring at the fringes of the site. Multi-level monitoring wells and surface water sampling points have been installed. Soil samples collected from the drilled wells are being used to provide inoculums for cultivating bacteria and identifying DNA. Preliminary data indicate a restricted lens of impacted groundwater that moves rapidly through the mine tailings and shallow bedrock fractures, but is contained by ambient groundwater from uncontaminated recharge areas. Sulfate reduction has been documented at the margins of the acid-generating area, and this has been reproduced in laboratory experiments. Current research is now examining the processes of Fe(III) and SO4 reduction and the roles of acidophilic and acid-tolerant anaerobic microorganisms. K12 teachers are part of the research teams and the effects of research experiences on their higher-level understanding of science are being evaluated.

Physiological adaptation of Escherichia coli after transfer onto refrigerated ground meat and other solid matrices: a molecular approach.

PubMed

Guernec, Anthony; Robichaud-Rincon, Philippe; Saucier, Linda

2012-10-01

Bacteria on meat are subjected to specific living conditions that differ drastically from typical laboratory procedures in synthetic media. This study was undertaken to determine the behavior of bacteria when transferred from a rich-liquid medium to solid matrices, as is the case during microbial process validation. Escherichia coli cultured in Brain-Heart Infusion (BHI) broth to different growth phases were inoculated in ground beef (GB) and stored at 5°C for 12 days or spread onto BHI agar and cooked meat medium (CMM), and incubated at 37°C for several hours. We monitored cell densities and the expression of σ factors and genes under their control over time. The initial growth phase of the inoculum influenced growth resumption after transfer onto BHI agar and CMM. Whatever the solid matrix, bacteria adapted to their new environment and did not perceive stress immediately after inoculation. During this period, the σ(E) and σ(H) regulons were not activated and rpoD mRNA levels adjusted quickly. The rpoS and gadA mRNA levels did not increase after inoculation on solid surfaces and displayed normal growth-dependent modifications. After transfer onto GB, dnaK and groEL gene expression was affected more by the low temperature than by the composition of a meat environment. Copyright © 2012 Elsevier Ltd. All rights reserved.

A dry-inoculation method for nut kernels.

PubMed

Blessington, Tyann; Theofel, Christopher G; Harris, Linda J

2013-04-01

A dry-inoculation method for almonds and walnuts was developed to eliminate the need for the postinoculation drying required for wet-inoculation methods. The survival of Salmonella enterica Enteritidis PT 30 on wet- and dry-inoculated almond and walnut kernels stored under ambient conditions (average: 23 °C; 41 or 47% RH) was then compared over 14 weeks. For wet inoculation, an aqueous Salmonella preparation was added directly to almond or walnut kernels, which were then dried under ambient conditions (3 or 7 days, respectively) to initial nut moisture levels. For the dry inoculation, liquid inoculum was mixed with sterilized sand and dried for 24 h at 40 °C. The dried inoculated sand was mixed with kernels, and the sand was removed by shaking the mixture in a sterile sieve. Mixing procedures to optimize the bacterial transfer from sand to kernel were evaluated; in general, similar levels were achieved on walnuts (4.8-5.2 log CFU/g) and almonds (4.2-5.1 log CFU/g). The decline of Salmonella Enteritidis populations was similar during ambient storage (98 days) for both wet-and dry-inoculation methods for both almonds and walnuts. The dry-inoculation method mimics some of the suspected routes of contamination for tree nuts and may be appropriate for some postharvest challenge studies. Copyright © 2012 Elsevier Ltd. All rights reserved.

Quasispecies evolution of the prototypical genotype 1 porcine reproductive and respiratory syndrome virus early during in vivo infection is rapid and tissue specific.

PubMed

Lu, Zen H; Wang, Xinglong; Wilson, Alison D; Dorey-Robinson, Daniel L W; Archibald, Alan L; Ait-Ali, Tahar; Frossard, Jean-Pierre

2017-08-01

Porcine reproductive and respiratory syndrome virus (PRRSV) is a major infectious threat to the pig industry worldwide. Increasing evidence suggests that microevolution within a quasispecies population can give rise to high sequence heterogeneity in PRRSV; potentially impacting the pathogenicity of the virus. Here, we report on micro-evolutionary events taking place within the viral quasispecies population in lung and lymph node 3 days post infection (dpi) following experimental in vivo infection with the prototypical Lelystad PRRSV (LV). Sequence analysis revealed 16 high frequency single nucleotide variants (SNV) or differences from the reference LV genome which are assumed to be representative of the consensus inoculum genome. Additionally, 49 other low frequency SNVs were also found in the inoculum population. At 3 dpi, a total of 9 and 10 SNVs of varying frequencies could already be detected in the LV population infecting the lung and lymph nodes, respectively. Interestingly, of these, three and four novel SNVs emerged independently in the two respective tissues when compared to the inoculum. The remaining variants, though already present at lower frequencies in the inoculum, were positively selected and their frequency increased within the quasispecies population. Hence, we were able to determine directly from tissues infected with PRRSV the repertoire of genetic variants within the viral quasispecies population. Our data also suggest that microevolution of these variants is rapid and some may be tissue-specific.

Pathogen translocation and histopathological lesions in an experimental model of Salmonella Dublin infection in calves receiving lactic acid bacteria and lactose supplements

PubMed Central

Zbrun, María V.; Soto, Lorena P.; Bertozzi, Ezequiel; Sequeira, Gabriel J.; Marti, Luis E.; Signorini, Marcelo L.; Armesto, Roberto Rodríguez; Rosmini, Marcelo R.

2012-01-01

The purpose of this study was to evaluate the capacity of a lactic acid bacteria (LAB) inoculum to protect calves with or without lactose supplements against Salmonella Dublin infection by evaluating histopathological lesions and pathogen translocation. Fifteen calves were divided into three groups [control group (C-G), a group inoculated with LAB (LAB-G), and a group inoculated with LAB and given lactose supplements (L-LAB-G)] with five, six, and four animals, respectively. The inoculum, composed of Lactobacillus (L.) casei DSPV 318T, L. salivarius DSPV 315T, and Pediococcus acidilactici DSPV 006T, was administered with milk replacer. The LAB-G and L-LAB-G received a daily dose of 109 CFU/kg body weight of each strain throughout the experiment. Lactose was provided to the L-LAB-G in doses of 100 g/day. Salmonella Dublin (2 × 1010 CFU) was orally administered to all animals on day 11 of the experiment. The microscopic lesion index values in target organs were 83%, 70%, and 64.3% (p < 0.05) for the C-G, LAB-G, and L-LAB-G, respectively. Administration of the probiotic inoculum was not fully effective against infection caused by Salmonella. Although probiotic treatment was unable to delay the arrival of pathogen to target organs, it was evident that the inoculum altered the response of animals against pathogen infection. PMID:23000583

A waste characterisation procedure for ADM1 implementation based on degradation kinetics.

PubMed

Girault, R; Bridoux, G; Nauleau, F; Poullain, C; Buffet, J; Steyer, J-P; Sadowski, A G; Béline, F

2012-09-01

In this study, a procedure accounting for degradation kinetics was developed to split the total COD of a substrate into each input state variable required for Anaerobic Digestion Model n°1. The procedure is based on the combination of batch experimental degradation tests ("anaerobic respirometry") and numerical interpretation of the results obtained (optimisation of the ADM1 input state variable set). The effects of the main operating parameters, such as the substrate to inoculum ratio in batch experiments and the origin of the inoculum, were investigated. Combined with biochemical fractionation of the total COD of substrates, this method enabled determination of an ADM1-consistent input state variable set for each substrate with affordable identifiability. The substrate to inoculum ratio in the batch experiments and the origin of the inoculum influenced input state variables. However, based on results modelled for a CSTR fed with the substrate concerned, these effects were not significant. Indeed, if the optimal ranges of these operational parameters are respected, uncertainty in COD fractionation is mainly limited to temporal variability of the properties of the substrates. As the method is based on kinetics and is easy to implement for a wide range of substrates, it is a very promising way to numerically predict the effect of design parameters on the efficiency of an anaerobic CSTR. This method thus promotes the use of modelling for the design and optimisation of anaerobic processes. Copyright © 2012 Elsevier Ltd. All rights reserved.

In vitro fermentation characteristics of diets with different forage/concentrate ratios: comparison of rumen and faecal inocula.

PubMed

Zicarelli, Fabio; Calabrò, Serena; Cutrignelli, Monica I; Infascelli, Federico; Tudisco, Raffaella; Bovera, Fulvia; Piccolo, Vincenzo

2011-05-01

The aim of this trial was to evaluate the replacement of rumen fluid with faeces as inoculum in studying the in vitro fermentation characteristics of diets for ruminants using the in vitro gas production technique. Six iso-protein diets with different forage/concentrate ratios were incubated with rumen fluid (RI) or faeces (FI) collected from sheep. Most of the fermentation parameters were influenced by diet and inoculum (P < 0.01). With both inocula, organic matter degradability (dOM), cumulative gas production (OMCV) and maximum fermentation rate (R(max) ) increased as the amount of concentrate in the diet increased. R(max) was lower with FI vs RI (P < 0.01); dOM was higher with FI vs RI and the diet × inoculum interaction was significant. As expected, with both inocula, R(max) increased as the neutral detergent fibre content of the diet decreased. Significant correlations were obtained using both inocula between OMCV/dOM and gas/volatile fatty acid (VFA), while the correlation VFA/dOM was significant only with FI. The microbial biomass yield calculated by stoichiometric analysis for all diets was higher with FI vs RI. With FI the organic matter used for microbial growth showed an overall decreasing trend as the amount of concentrate in the diet increased. The results indicate that both faeces and rumen fluid from sheep have the potential to be used as inoculum for the in vitro gas production technique. Copyright © 2011 Society of Chemical Industry.

Cost-effective approach to ethanol production and optimization by response surface methodology.

PubMed

Uncu, Oya Nihan; Cekmecelioglu, Deniz

2011-04-01

Food wastes disposed from residential and industrial kitchens have gained attention as a substrate in microbial fermentations to reduce product costs. In this study, the potential of simultaneously hydrolyzing and subsequently fermenting the mixed carbohydrate components of kitchen wastes were assessed and the effects of solid load, inoculum volume of baker's yeast, and fermentation time on ethanol production were evaluated by response surface methodology (RSM). The enzymatic hydrolysis process was complete within 6h. Fermentation experiments were conducted at pH 4.5, a temperature of 30°C, and agitated at 150 rpm without adding the traditional fermentation nutrients. The statistical analysis of the model developed by RSM suggested that linear effects of solid load, inoculum volume, and fermentation time and the quadratic effects of inoculum volume and fermentation time were significant (P<0.05). The verification experiments indicated that the developed model could be successfully used to predict ethanol concentration at >90% accuracy. An optimum ethanol concentration of 32.2g/l giving a yield of 0.40g/g, comparable to yields reported to date, was suggested by the model with 20% solid load, 8.9% inoculum volume, and 58.8h of fermentation. The results indicated that the production costs can be lowered to a large extent by using kitchen wastes having multiple carbohydrate components and eliminating the use of traditional fermentation nutrients from the recipe. Copyright © 2010 Elsevier Ltd. All rights reserved.

Combined "de novo" and "ex novo" lipid fermentation in a mix-medium of corncob acid hydrolysate and soybean oil by Trichosporon dermatis.

PubMed

Huang, Chao; Luo, Mu-Tan; Chen, Xue-Fang; Qi, Gao-Xiang; Xiong, Lian; Lin, Xiao-Qing; Wang, Can; Li, Hai-Long; Chen, Xin-De

2017-01-01

Microbial oil is one important bio-product for its important function in energy, chemical, and food industry. Finding suitable substrates is one key issue for its industrial application. Both hydrophilic and hydrophobic substrates can be utilized by oleaginous microorganisms with two different bio-pathways (" de novo " lipid fermentation and " ex novo " lipid fermentation). To date, most of the research on lipid fermentation has focused mainly on only one fermentation pathway and little work was carried out on both " de novo " and " ex novo " lipid fermentation simultaneously; thus, the advantages of both lipid fermentation cannot be fulfilled comprehensively. In this study, corncob acid hydrolysate with soybean oil was used as a mix-medium for combined " de novo " and " ex novo " lipid fermentation by oleaginous yeast Trichosporon dermatis . Both hydrophilic and hydrophobic substrates (sugars and soybean oil) in the medium can be utilized simultaneously and efficiently by T. dermatis . Different fermentation modes were compared and the batch mode was the most suitable for the combined fermentation. The influence of soybean oil concentration, inoculum size, and initial pH on the lipid fermentation was evaluated and 20 g/L soybean oil, 5% inoculum size, and initial pH 6.0 were suitable for this bioprocess. By this technology, the lipid composition of extracellular hydrophobic substrate (soybean oil) can be modified. Although adding emulsifier showed little beneficial effect on lipid production, it can modify the intracellular lipid composition of T. dermatis . The present study proves the potential and possibility of combined " de novo " and " ex novo " lipid fermentation. This technology can use hydrophilic and hydrophobic sustainable bio-resources to generate lipid feedstock for the production of biodiesel or other lipid-based chemical compounds and to treat some special wastes such as oil-containing wastewater.

Effect of inoculum and sulfide type on simultaneous hydrogen sulfide removal from biogas and nitrogen removal from swine slurry and microbial mechanism.

PubMed

Wang, Lan; Wei, Benping; Chen, Ziai; Deng, Liangwei; Song, Li; Wang, Shuang; Zheng, Dan; Liu, Yi; Pu, Xiaodong; Zhang, Yunhong

2015-12-01

Four reactors were initiated to study the effect of inoculum and sulfide type on the simultaneous hydrogen sulfide removal from biogas and nitrogen removal from swine slurry (Ssu-Nir) process. Anaerobic sludge, aerobic sludge, and water were used as inocula, and Na2S and biogas were used as a sulfide substrate, respectively. Additionally, 454 pyrosequencing of the 16S rRNA gene was used to explore the bacterial diversity. The results showed that sulfur-oxidizing bacteria (Thiobacillus, 42.2-84.4 %) were dominant in Ssu-Nir process and led to the excellent performance. Aerobic sludge was more suitable for inoculation of the Ssu-Nir process because it is better for rapidly enriching dominant sulfur-oxidizing bacteria (Thiobacillus, 54.4 %), denitrifying sulfur-oxidizing bacteria (40.0 %) and denitrifiers (23.9 %). Lower S(2-) removal efficiency (72.6 %) and NO3 (-) removal efficiency (<90 %) of the Ssu-Nir process were obtained using biogas as a sulfide substrate than when Na2S was used. For the Ssu-Nir process with biogas as the sulfide substrate, limiting H2S absorption caused a high relative abundance of sulfur-oxidizing bacteria, Thiobacillus (84.8 %) and Thiobacillus sayanicus (39.6 %), which in turn led to low relative abundance of denitrifiers (1.6 %) and denitrifying sulfur-oxidizing bacteria (24.4 %), low NO3 (-) removal efficiency, and eventually poor performance.

Transcriptome Profiling of Lotus japonicus Roots During Arbuscular Mycorrhiza Development and Comparison with that of Nodulation

PubMed Central

Deguchi, Yuichi; Banba, Mari; Shimoda, Yoshikazu; Chechetka, Svetlana A.; Suzuri, Ryota; Okusako, Yasuhiro; Ooki, Yasuhiro; Toyokura, Koichi; Suzuki, Akihiro; Uchiumi, Toshiki; Higashi, Shiro; Abe, Mikiko; Kouchi, Hiroshi; Izui, Katsura; Hata, Shingo

2007-01-01

Abstract To better understand the molecular responses of plants to arbuscular mycorrhizal (AM) fungi, we analyzed the differential gene expression patterns of Lotus japonicus, a model legume, with the aid of a large-scale cDNA macroarray. Experiments were carried out considering the effects of contaminating microorganisms in the soil inoculants. When the colonization by AM fungi, i.e. Glomus mosseae and Gigaspora margarita, was well established, four cysteine protease genes were induced. In situ hybridization revealed that these cysteine protease genes were specifically expressed in arbuscule-containing inner cortical cells of AM roots. On the other hand, phenylpropanoid biosynthesis-related genes for phenylalanine ammonia-lyase (PAL), chalcone synthase, etc. were repressed in the later stage, although they were moderately up-regulated on the initial association with the AM fungus. Real-time RT–PCR experiments supported the array experiments. To further confirm the characteristic expression, a PAL promoter was fused with a reporter gene and introduced into L. japonicus, and then the transformants were grown with a commercial inoculum of G. mosseae. The reporter activity was augmented throughout the roots due to the presence of contaminating microorganisms in the inoculum. Interestingly, G. mosseae only colonized where the reporter activity was low. Comparison of the transcriptome profiles of AM roots and nitrogen-fixing root nodules formed with Mesorhizobium loti indicated that the PAL genes and other phenylpropanoid biosynthesis-related genes were similarly repressed in the two organs. PMID:17634281

A meta-analysis of the published literature on the effectiveness of antimicrobial soaps.

PubMed

Montville, Rebecca; Schaffner, Donald W

2011-11-01

The goal of this research was to conduct a systematic quantitative analysis of the existing data in the literature in order to determine if there is a difference between antimicrobial and nonantimicrobial soaps and to identify the methodological factors that might affect this difference. Data on hand washing efficacy and experimental conditions (sample size, wash duration, soap quantity, challenge organism, inoculum size, and neutralization method) from published studies were compiled and transferred to a relational database. A total of 25 publications, containing 374 observations, met the study selection criteria. The majority of the studies included fewer than 15 observations with each treatment and included a direct comparison between nonantimicrobial soap and antimicrobial soap. Although differences in efficacy between antimicrobial and nonantimicrobial soap were small (∼0.5-log CFU reduction difference), antimicrobial soap produced consistently statistically significantly greater reductions. This difference was true for any of the antimicrobial compounds investigated where n was >20 (chlorhexidine gluconate, iodophor, triclosan, or povidone). Average log reductions were statistically significantly greater (∼2 log CFU) when either gram-positive or gram-negative transient organisms were deliberately added to hands compared with experiments done with resident hand flora (∼0.5 log CFU). Our findings support the importance of using a high initial inoculum on the hands, well above the detection limit. The inherent variability in hand washing seen in the published literature underscores the importance of using a sufficiently large sample size to detect differences when they occur.

Effect of feed to inoculum ratios on biogas yields of food and green wastes.

PubMed

Liu, Guangqing; Zhang, Ruihong; El-Mashad, Hamed M; Dong, Renjie

2009-11-01

Biogas and methane yields of food and green wastes and their mixture were determined using batch anaerobic digesters at mesophilic (35+/-2 degrees C) and thermophilic (50+/-2 degrees C) temperatures. The mixture was composed of 50% food waste and 50% green waste, based on the volatile solids (VS) initially added to the reactors. The thermophilic digestion tests were performed with four different feed to inoculum (F/I) ratios (i.e., 1.6, 3.1, 4.0 and 5.0) and the mesophilic digestion was conducted at one F/I (3.1). The results showed that the F/I significantly affected the biogas production rate. At four F/Is tested, after 25 days of thermophilic digestion, the biogas yield was determined to be 778, 742, 784 and 396 mL/g VS for food waste, respectively; 631, 529, 524 and 407 mL/g VS for green waste, respectively; and 716, 613, 671 and 555 mL/g VS for the mixture, respectively. About 80% of the biogas production was obtained during the first 10 days of digestion. At the F/I of 3.1, the biogas and methane yields from mesophilic digestion of food waste, green waste and their mixture were lower than the yields obtained at thermophilic temperature. The biogas yields were 430, 372 and 358 mL/g VS, respectively, and the methane yields were 245, 206, and 185 mL/g VS, respectively.

[Experimental and clinical evaluation of cefotetan in pediatrics].

PubMed

Toyonaga, Y; Kurosu, Y; Sugita, M; Kita, A; Yoshino, N; Kouda, N; Kumagai, K; Horiuchi, K; Hori, M; Takahashi, T

1983-06-01

Preclinical and clinical studies were carried out on cefotetan (CTT), a new synthetic cephamycin antibacterial agent. The results are described below. Antibacterial activity The minimum inhibitory concentrations (MICs) of CTT, CEZ, CTM and CMZ were determined against clinical isolates of S. aureus, E. coli, K. pneumoniae and P. mirabilis. To CTT S. aureus, showed its sensitivity peak (in the graphic plot of the MIC distribution) at a concentration range of 3.13-6.25 micrograms/ml when a 100-fold dilution of the pathological specimen was employed as the inoculum. These results were inferior to those with CEZ and CTM by 2-4 concentration tubes. The CTT results were also about 2 tubes inferior to the results with CMZ, which is a cephamycin antibiotic. On the other hand, CTT was found to show very strong antibacterial activity against Gram-negative rods. For example, the sensitivity peak of E. coli, occurred at an antibiotic concentration of less than or equal to 0.1-0.2 microgram/ml, regardless of whether the inoculum was the undiluted pathological specimen or the 100-fold dilution thereof. Similar results were obtained in relation to the K. pneumoniae strains: at a CTT concentration of less than or equal to 0.1 microgram/ml, suppression of growth was achieved in 74% of the strains when the inocula were the undiluted specimens, and 86% when the inocula were the 100-fold dilutions thereof. In addition, against P. mirabilis, when the inoculum consisted of the undiluted pathological specimen the MIC peak for CTT occurred at a concentration range of 0.39-0.78 microgram/ml, whereas the peak occurred at 0.2-0.39 microgram/ml when the bacterial inoculum was the 100-fold dilution of the collected specimen. In contrast, CTM showed slightly stronger antibacterial activity than CTT in relation to P. mirabilis; that is, its MIC peak occurred at less than or equal to 0.1-0.2 microgram/ml when the inoculum was the undiluted pathological specimen, and at less than or equal to 0.1 microgram/ml when the bacterial inoculum was the 100-fold dilution. Otherwise, against these 3 species of bacteria, CTT yielded results which were clearly superior to those achieved with the other 3 antibiotics. Absorption and excretion CTT was administered to children at a dosage of 10 mg/kg and 20 mg/kg as a one-shot intravenous injection or as a 1-hour intravenous drip infusion. Thereafter, the serum concentration of the antibiotic was monitored and it excretion rate in the urine was also determined.(ABSTRACT TRUNCATED AT 400 WORDS)

High Level Ethanol from Sugar Cane Molasses by a New Thermotolerant Saccharomyces cerevisiae Strain in Industrial Scale.

PubMed

Fadel, M; Keera, Abeer A; Mouafi, Foukia E; Kahil, Tarek

2013-01-01

A new local strain of S. cerevisiae F-514, for ethanol production during hot summer season, using Egyptian sugar cane molasses was applied in Egyptian distillery factory. The inouluum was propagated through 300 L, 3 m(3), and 12 m(3) fermenters charged with diluted sugar cane molasses containing 4%-5% sugars. The yeast was applied in fermentation vessels 65 m(3) working volume to study the varying concentrations of urea, DAP, orthophosphoric acid (OPA), and its combinations as well as magnesium sulfate and inoculum size. The fermenter was allowed to stay for a period of 20 hours to give time for maximum conversion of sugars into ethanol. S. cerevisiae F-514 at molasses sugar level of 18% (w/v), inoculum size of 20% (v/v) cell concentration of 3.0 × 10(8)/mL, and combinations of urea, diammonium phosphate (DAP), orthophosphoric acid (OPA), and magnesium sulfate at amounts of 20, 10, 5, and 10 kg/65 m(3) working volume fermenters, respectively, supported maximum ethanol production (9.8%, v/v), fermentation efficiency (FE) 88.1%, and remaining sugars (RS) 1.22%. The fermentation resulted 13.4 g dry yeast/L contained 34.6% crude protein and 8.2% ash. By selecting higher ethanol yielding yeast strain and optimizing, the fermentation parameters both yield and economics of the fermentation process can be improved.

Effect of Inoculum Dosage Aspergillus niger and Rhizopus oryzae mixture with Fermentation Time of Oil Seed Cake (Jatropha curcas L) to the content of Protein and Crude Fiber

NASA Astrophysics Data System (ADS)

Kurniati, T.; Nurlaila, L.; Iim

2017-04-01

Jatropha curcas L already widely cultivated for its seeds pressed oil used as an alternative fuel. This plant productivity per hectare obtained 2.5-5 tonnes of oil/ha / year and jatropha seed cake from 5.5 to 9.5 tonnes/ha/year, nutrient content of Jatropha curcas seed L potential to be used as feed material, However, the constraints faced was the low crude protein and high crude protein. The purpose of the research was to determine the dosage of inoculum and fermentation time of Jatropha seed cake by a mixture of Aspergillus niger and Rhizopus oryzae on crude protein and crude fibre. The study was conducted by an experimental method using a Completely Randomised Design (CRD) factorial design (3×3). The treatment consisted of a mixture of three dosage levels of Aspergillus niger and Rhizopus oryzae (= 0.2% d1, d2 and d3 = 0.3% = 0.4%) and three levels of fermentation time (w1 = 72 hours, 96 hours and w2 = w3 = 120 hours) each repeated three times. The parameters measured were crude protein and crude fibre. The results showed that dosages of 0.3% (Aspergillus niger Rhizopus oryzae 0.15% and 0.15%) and 72 hours (d2w1) is the dosage and the optimal time to generate the highest crude protein content of 21.11% and crude fibre amounted to 21.36%.

Removal of copper from aqueous solution by electrodeposition in cathode chamber of microbial fuel cell.

PubMed

Tao, Hu-Chun; Liang, Min; Li, Wei; Zhang, Li-Juan; Ni, Jin-Ren; Wu, Wei-Min

2011-05-15

Based on energetic analysis, a novel approach for copper electrodeposition via cathodic reduction in microbial fuel cells (MFCs) was proposed for the removal of copper and recovery of copper solids as metal copper and/or Cu(2)O in a cathode with simultaneous electricity generation with organic matter. This was examined by using dual-chamber MFCs (chamber volume, 1L) with different concentrations of CuSO(4) solution (50.3 ± 5.8, 183.3 ± 0.4, 482.4 ± 9.6, 1007.9 ± 52.0 and 6412.5 ± 26.7 mg Cu(2+)/L) as catholyte at pH 4.7, and different resistors (0, 15, 390 and 1000 Ω) as external load. With glucose as a substrate and anaerobic sludge as an inoculum, the maximum power density generated was 339 mW/m(3) at an initial 6412.5 ± 26.7 mg Cu(2+)/L concentration. High Cu(2+) removal efficiency (>99%) and final Cu(2+) concentration below the USA EPA maximum contaminant level (MCL) for drinking water (1.3mg/L) was observed at an initial 196.2 ± 0.4 mg Cu(2+)/L concentration with an external resistor of 15 Ω, or without an external resistor. X-ray diffraction analysis confirmed that Cu(2+) was reduced to cuprous oxide (Cu(2)O) and metal copper (Cu) on the cathodes. Non-reduced brochantite precipitates were observed as major copper precipitates in the MFC with a high initial Cu(2+) concentration (0.1M) but not in the others. The sustainability of high Cu(2+) removal (>96%) by MFC was further examined by fed-batch mode for eight cycles. Copyright © 2011 Elsevier B.V. All rights reserved.

Comparative Activities of Ciprofloxacin and Levofloxacin against Streptococcus pneumoniae in an In Vitro Dynamic Model

PubMed Central

Zinner, Stephen H.; Simmons, Kelly; Gilbert, Deborah

2000-01-01

The activities of levofloxacin (500 mg every 24 h) and ciprofloxacin (750 mg every 12 h) against six pneumococcal isolates in an in vitro dynamic model were compared. For one strain, levofloxacin reduced the inoculum by over 4 log CFU/ml and ciprofloxacin reduced the inoculum by over 2 log CFU/ml. For four isolates, both drugs reduced inocula by 4 log CFU/ml within 6 h, suggesting that this dose of ciprofloxacin should be as effective as levofloxacin against these pneumococci. PMID:10681356

Rotylenchulus reniformis on Greenhouse-grown Foliage Plants: Host Range and Sources of Inoculum.

PubMed

Starr, J L

1991-10-01

Two sources of inoculum of reniform nematodes, Rotylenchulus reniformis, were identified for infestation of ornamental foliage plants in commercial greenhouses. These were water from a local canal system and rooted cuttings purchased from other sources. Eight ornamental plant species were identified as good hosts for the reniform nematode, with each species supporting a reniform population density equal to or greater than that supported by 'Rutgers' tomato and a reproduction factor of greater than 1.0. Nine other plant species were identified as poor hosts.

Rotylenchulus reniformis on Greenhouse-grown Foliage Plants: Host Range and Sources of Inoculum

PubMed Central

Starr, J. L.

1991-01-01

Two sources of inoculum of reniform nematodes, Rotylenchulus reniformis, were identified for infestation of ornamental foliage plants in commercial greenhouses. These were water from a local canal system and rooted cuttings purchased from other sources. Eight ornamental plant species were identified as good hosts for the reniform nematode, with each species supporting a reniform population density equal to or greater than that supported by 'Rutgers' tomato and a reproduction factor of greater than 1.0. Nine other plant species were identified as poor hosts. PMID:19283176

Phosphorus supply, arbuscular mycorrhizal fungal species, and plant genotype impact on the protective efficacy of mycorrhizal inoculation against wheat powdery mildew.

PubMed

Mustafa, G; Randoux, B; Tisserant, B; Fontaine, J; Magnin-Robert, M; Lounès-Hadj Sahraoui, A; Reignault, Ph

2016-10-01

A potential alternative strategy to chemical control of plant diseases could be the stimulation of plant defense by arbuscular mycorrhizal fungi (AMF). In the present study, the influence of three parameters (phosphorus supply, mycorrhizal inoculation, and wheat cultivar) on AMF protective efficiency against Blumeria graminis f. sp. tritici, responsible for powdery mildew, was investigated under controlled conditions. A 5-fold reduction (P/5) in the level of phosphorus supply commonly recommended for wheat in France improved Funneliformis mosseae colonization and promoted protection against B. graminis f. sp. tritici in a more susceptible wheat cultivar. However, a further decrease in P affected plant growth, even under mycorrhizal conditions. Two commercially available AMF inocula (F. mosseae, Solrize®) and one laboratory inoculum (Rhizophagus irregularis) were tested for mycorrhizal development and protection against B. graminis f. sp. tritici of two moderately susceptible and resistant wheat cultivars at P/5. Mycorrhizal levels were the highest with F. mosseae (38 %), followed by R. irregularis (19 %) and Solrize® (SZE, 8 %). On the other hand, the highest protection level against B. graminis f. sp. tritici was obtained with F. mosseae (74 %), followed by SZE (58 %) and R. irregularis (34 %), suggesting that inoculum type rather than mycorrhizal levels determines the protection level of wheat against B. graminis f. sp. tritici. The mycorrhizal protective effect was associated with a reduction in the number of conidia with haustorium and with an accumulation of polyphenolic compounds at B. graminis f. sp. tritici infection sites. Both the moderately susceptible and the most resistant wheat cultivar were protected against B. graminis f. sp. tritici infection by F. mosseae inoculation at P/5, although the underlying mechanisms appear rather different between the two cultivars. This study emphasizes the importance of taking into account the considered parameters when considering the use of AMF as biocontrol agents.

Histological and serological evidence of experimental paracoccidioidomycosis in Calomys callosus (Rodentia: Cricetidae)

PubMed Central

Berbert, Alceu LCV; Faria, Gabriele G; Gennari-Cardoso, Margareth L; Silva, Maria MMD; Mineo, José R; Loyola, Adriano M

2007-01-01

The responses of animal experimental models related to the infectivity, virulence and pathogenicity of Paracoccidioides brasiliensis is constantly used to develop new perspectives of investigation. The rodent Calomys callosus, Rengger 1830 (Rodentia: Cricetidae) is an indigenous inhabitant of the savannah environment found in the central regions of Brazil. The aim of the present work was to evaluate the histopathological and serological features of C. callosus after inoculation with the Pb18 strain of P. brasiliensis. Furthermore, A/Sn and B10.A mice strains were also tested to compare the results obtained in C. callosus to these well-established experimental models of resistance and susceptibility respectively. In every instance, survival analysis was performed, and histopathological study of the lungs, liver and spleen was employed to investigate tissue involvement, degree of inflammation and fungal presence. Levels of antibodies to P. brasiliensis were measured by using an enzyme-linked immunosorbent assay after 4 weeks and at the advanced stage of infection. The mortality rate was proportional to inoculation dose in all groups, but overall it was much superior in C. callosus than in the B10.A-susceptible mice. Macroscopical and microscopical pathological alterations were also more extensive and remarkable for C. callosus, once again proportional to inoculation dose, but more noticeable differences among the studied groups were found with 0.6 × 105 inoculum. In addition, the serological profile of C. callosus was similar to that found for B10.A-susceptible mice. Infection of C. callosus with 0.6 × 108 Pb18 inoculum resulted in more serious illness, and it decreased in severity in proportion to the inoculum dose. This difference was more pronounced in C. callosus, and the clinical, serological and pathological findings in this animal were more intense and precocious compared with the B10.A-susceptible mice. The present results suggest that C. callosus is a potentially alternative experimental animal model for paracoccidioidomycosis infection. PMID:17244339

Culture Conditions for Production of Biomass, Adenosine, and Cordycepin from Cordyceps sinensis CS1197: Optimization by Desirability Function Method

PubMed Central

Ghatnur, Shashidhar M.; Parvatam, Giridhar; Balaraman, Manohar

2015-01-01

Background: Cordyceps sinensis (CS) is a traditional Chinese medicine contains potent active metabolites such as nucleosides and polysaccharides. The submerged cultivation technique is studied for the large scale production of CS for biomass and metabolites production. Objective: To optimize culture conditions for large-scale production of CS1197 biomass and metabolites production. Materials and Methods: The CS1197 strain of CS was isolated from dead larvae of natural CS and the authenticity was assured by the presence of two major markers adenosine and cordycepin by high performance liquid chromatography and mass spectrometry. A three-level Box-Behnken design was employed to optimize process parameters culturing temperature, pH, and inoculum volume for the biomass yield, adenosine and cordycepin. The experimental results were regressed to a second-order polynomial equation by a multiple regression analysis for the prediction of biomass yield, adenosine and cordycepin production. Multiple responses were optimized based on desirability function method. Results: The desirability function suggested the process conditions temperature 28°C, pH 7 and inoculum volume 10% for optimal production of nutraceuticals in the biomass. The water extracts from dried CS1197 mycelia showed good inhibition for 2 diphenyl-1-picrylhydrazyl and 2,2-azinobis-(3-ethyl-benzo-thiazoline-6-sulfonic acid-free radicals. Conclusion: The result suggests that response surface methodology-desirability function coupled approach can successfully optimize the culture conditions for CS1197. SUMMARY Authentication of CS1197 strain by the presence of adenosine and cordycepin and culturing period was determined to be for 14 daysContent of nucleosides in natural CS was found higher than in cultured CS1197 myceliumBox-Behnken design to optimize critical cultural conditions: temperature, pH and inoculum volumeWater extract showed better antioxidant activity proving credible source of natural antioxidants. PMID:26929580

Differential impact of metacyclic and blood trypomastigotes on parasitological, serological and phenotypic features triggered during acute Trypanosoma cruzi infection in dogs.

PubMed

Carneiro, Cláudia Martins; Martins-Filho, Olindo Assis; Reis, Alexandre Barbosa; Veloso, Vanja Maria; Araújo, Flávio Marcos Gomes; Bahia, Maria Terezinha; de Lana, Marta; Machado-Coelho, George Luiz Lins; Gazzinelli, Giovanni; Correa-Oliveira, Rodrigo; Tafuri, Washington Luiz

2007-02-01

A detailed follow-up investigation of the major parasitological, serological and phenotypic features in dogs experimentally infected with metacyclic (MT) and blood (BT) trypomastigotes of Trypanosoma cruzi strain Berenice-78, typifying vectorial and transfusional transmission of human Chagas disease, has been conducted. Although there were no changes with respect to the window of patent-parasitaemia, significant differences between MT- and BT-infected dogs in both the prepatent period (days 23 and 19, respectively) and the day of maximum parasitaemia (days 26 and 22, respectively) were recorded. A progressive enhancement in the level of T. cruzi-specific antibodies accompanied infection by both MT and BT forms, although higher IgG titres developed on days 14 and 21 following infection with MT forms. Higher Thy-1(+)/CD21(+) and lower CD4(+)/CD8(+) cell ratios, occasioned by increased levels of Thy-1(+) and CD8(+) T-cells and reduced frequencies of CD4(+) T-cells and CD21(+) B-lymphocytes, were observed in both MT- and BT-infected animals. The reduced frequency of CD14(+) leukocytes was revealed as the most relevant phenotypic feature intrinsic to T. cruzi infection independent of inoculum source. BT-specific phenotypic features included an early reduction in the percentage of circulating CD21(+) and CD14(+) leukocytes, together with a higher Thy-1(+)/CD21(+) cell ratio on day 42. On the other hand, higher levels of CD8(+) T-cells, together with a lower CD4(+)/CD8(+) cell ratio on day 28, were characteristic of MT infection. These findings emphasise the importance of inoculum source and suggest that vectorial or transfusional routes of T. cruzi infection may trigger distinct parasite-host interactions during acute Chagas disease.

Saccharomyces boulardii CNCM I-745 supplementation reduces gastrointestinal dysfunction in an animal model of IBS

PubMed Central

Scarpa, Melania; Marchiori, Chiara; Sarasin, Gloria; Caputi, Valentina; Porzionato, Andrea; Giron, Maria Cecilia; Palù, Giorgio; Castagliuolo, Ignazio

2017-01-01

Background We evaluated the effect of Saccharomyces boulardii CNCM I-745 on intestinal neuromuscular anomalies in an IBS-type mouse model of gastrointestinal motor dysfunctions elicited by Herpes Simplex Virus type 1 (HSV-1) exposure. Methods Mice were inoculated intranasally with HSV-1 (102 PFU) or vehicle at time 0 and 4 weeks later by the intragastric (IG) route (108 PFU). Six weeks after IG inoculum, mice were randomly allocated to receive oral gavage with either S. boulardii (107 CFU/day) or vehicle. After 4 weeks the following were determined: a) intestinal motility using fluorescein-isothiocyanate dextran distribution in the gut, fecal pellet expulsion, stool water content, and distal colonic transit of glass beads; b) integrity of the enteric nervous system (ENS) by immunohistochemistry on ileal whole-mount preparations and western blot of protein lysates from ileal longitudinal muscle and myenteric plexus; c) isometric muscle tension with electric field and pharmacological (carbachol) stimulation of ileal segments; and d) intestinal inflammation by levels of tumor necrosis factor α, interleukin(IL)-1β, IL-10 and IL-4. Results S. boulardii CNCM I-745 improved HSV-1 induced intestinal dysmotility and alteration of intestinal transit observed ten weeks after IG inoculum of the virus. Also, the probiotic yeast ameliorated the structural alterations of the ENS induced by HSV-1 (i.e., reduced peripherin immunoreactivity and expression, increased glial S100β protein immunoreactivity and neuronal nitric oxide synthase level, reduced substance P-positive fibers). Moreover, S. boulardii CNCM I-745 diminished the production of HSV-1 associated pro-inflammatory cytokines in the myenteric plexus and increased levels of anti-inflammatory interleukins. Conclusions S. boulardii CNCM I-745 ameliorated gastrointestinal neuromuscular anomalies in a mouse model of gut dysfunctions typically observed with irritable bowel syndrome. PMID:28732069

Saccharomyces boulardii CNCM I-745 supplementation reduces gastrointestinal dysfunction in an animal model of IBS.

PubMed

Brun, Paola; Scarpa, Melania; Marchiori, Chiara; Sarasin, Gloria; Caputi, Valentina; Porzionato, Andrea; Giron, Maria Cecilia; Palù, Giorgio; Castagliuolo, Ignazio

2017-01-01

We evaluated the effect of Saccharomyces boulardii CNCM I-745 on intestinal neuromuscular anomalies in an IBS-type mouse model of gastrointestinal motor dysfunctions elicited by Herpes Simplex Virus type 1 (HSV-1) exposure. Mice were inoculated intranasally with HSV-1 (102 PFU) or vehicle at time 0 and 4 weeks later by the intragastric (IG) route (108 PFU). Six weeks after IG inoculum, mice were randomly allocated to receive oral gavage with either S. boulardii (107 CFU/day) or vehicle. After 4 weeks the following were determined: a) intestinal motility using fluorescein-isothiocyanate dextran distribution in the gut, fecal pellet expulsion, stool water content, and distal colonic transit of glass beads; b) integrity of the enteric nervous system (ENS) by immunohistochemistry on ileal whole-mount preparations and western blot of protein lysates from ileal longitudinal muscle and myenteric plexus; c) isometric muscle tension with electric field and pharmacological (carbachol) stimulation of ileal segments; and d) intestinal inflammation by levels of tumor necrosis factor α, interleukin(IL)-1β, IL-10 and IL-4. S. boulardii CNCM I-745 improved HSV-1 induced intestinal dysmotility and alteration of intestinal transit observed ten weeks after IG inoculum of the virus. Also, the probiotic yeast ameliorated the structural alterations of the ENS induced by HSV-1 (i.e., reduced peripherin immunoreactivity and expression, increased glial S100β protein immunoreactivity and neuronal nitric oxide synthase level, reduced substance P-positive fibers). Moreover, S. boulardii CNCM I-745 diminished the production of HSV-1 associated pro-inflammatory cytokines in the myenteric plexus and increased levels of anti-inflammatory interleukins. S. boulardii CNCM I-745 ameliorated gastrointestinal neuromuscular anomalies in a mouse model of gut dysfunctions typically observed with irritable bowel syndrome.

Studying the growth boundary and subsequent time to growth of pathogenic Escherichia coli serotypes by turbidity measurements.

PubMed

Valero, A; Rodríguez, M; Carrasco, E; Pérez-Rodríguez, F; García-Gimeno, R M; Zurera, G

2010-09-01

The presence of Escherichia coli in contaminated food products is commonly attributed to faecal contamination when they are improperly handled and/or when inactivation treatments fail. Adaptation of E. coli at low pH and a(w) levels can vary at different temperatures depending on the serotype, thus more detailed studies are needed. In this work, a screening to assess the growth of four pathogenic serotypes of E. coli (O55:H6; O59:H21; O158:H23 and O157:H7) was performed. Subsequently, boundary models were elaborated with the fastest serotype selected at different temperatures (8, 12 and 16 degrees C), and inoculum levels (2, 3 and 4log cfu/mL) as function of pH (7.00-5.00) and a(w) (0.999-0.960). Finally, the growth kinetics of E. coli was described in the conditions that allowed growth. Results obtained showed that the serotypes O157:H7 and O59:H21 did not grow at more stringent conditions (8 degrees C; pH 5.50), while the E. coli O158:H23 was the best adapted, resulting in faster growth. The logistic regression models presented a good adjustment to data observed since more than 96.7% of cases were correctly classified. The growth interface was shifted to more limited conditions as the inoculum size was higher. Detection times (t(d), h) and their variability were higher at low levels of the environmental factors studied. This work provides insight on the growth kinetics of E. coli at various environmental conditions. Copyright 2010 Elsevier Ltd. All rights reserved.

Survival and reproduction of some nematodes as affected by muck and organic acids.

PubMed

Elmiligy, I A; Norton, D C

1973-01-01

Fulvic, humic, acetic, N-bulyric, formic, lactic, and propionic acids were inhibitory to the survival or reproduction of Aphelenchus avenae, Aphelenchoides goodeyi, Helicotylenchus pseudorobustus, Meloidogyne hapla or Xiphinema americanum. Reproduction of H. pseudorobustus and M. hapla significantly increased with increasing amounts of muck added to sand, and with the initial amount of nematode inoculum. All acids except humic and fulvic were lethal, in vitro, to all nematode species tested. When A. goodeyi was treated with fulvic acid, reproduction was reduced significantly when compared with sodium humate or water treatments. Treatment of H. pseudorobustus with fulvic acid (pH 3.5) resulted in a greater reduction in reproduction in soil than did treatment with humic acid (pH 3.5).

Isolation, characterization and optimization of culture parameters for production of an alkaline protease isolated from Aspergillus tamarii.

PubMed

Anandan, Dayanandan; Marmer, William N; Dudley, Robert L

2007-05-01

Aspergillus tamarii expresses an extracellular alkaline protease that we show to be effective in removing hair from cattle hide. Large quantities of the enzyme will be required for the optimization of the enzymatic dehairing process so the growth conditions for maximum protease expression by A. tamarii were optimized for both solid-state culture on wheat bran and for broth culture. Optimal protease expression occurred, for both cultural media, at initial pH 9; the culture was incubated at 30 degrees C for 96 h using a 5% inoculum. The crude enzyme was isolated, purified and characterized using MALDI TOF TOF. The alkaline protease was homologous to the alkaline protease expressed by Aspergillus viridinutans.

Antimicrobial activity of polyphenol-rich fractions from Sida alba L. (Malvaceae) against co-trimoxazol-resistant bacteria strains.

PubMed

Konaté, Kiessoun; Hilou, Adama; Mavoungou, Jacques François; Lepengué, Alexis Nicaise; Souza, Alain; Barro, Nicolas; Datté, Jacques Y; M'batchi, Bertrand; Nacoulma, Odile Germaine

2012-02-24

The increased resistance of microorganisms to the currently used antimicrobials has lead to the evaluation of other agents that might have antimicrobial activity. Medicinal plants are sources of phytochemicals which are able to initiate different biological activities including antimicrobials In vitro antibacterial (MIC, MBC and time-kill studies) of polyphenol-rich fractions from Sida alba L. (Malvaceae) was assessed using ten bacteria strains (Gram-negative and Gram-positive). All test bacteria were susceptible to the polyphenol-rich fractions. Time-kill results showed that after 5 h exposition there was no viable microorganism in the initial inoculum and the effect of polyphenol-rich fractions was faster on Enterococcus faecalis (Gram-positive bacterium) comparatively to the other bacteria strains. The data analysis indicates that the tested of polyphenol-rich fractions has significant effects when compared with the standard antibiotic. These results therefore justify the traditional use of sida alba L., alone or in combination with other herbs to treat bacterial infections.

Enhancement of hexavalent chromium reduction and electricity production from a biocathode microbial fuel cell.

PubMed

Huang, Liping; Chen, Jingwen; Quan, Xie; Yang, Fenglin

2010-10-01

Enhancement of Cr (VI) reduction rate and power production from biocathode microbial fuel cells (MFCs) was achieved using indigenous bacteria from Cr (VI)-contaminated site as inoculum and MFC architecture with a relatively large cathode-specific surface area of 340-900 m2 m(-3). A specific Cr (VI) reduction rate of 2.4 ± 0.2 mg g(-1)VSS h(-1) and a power production of 2.4 ± 0.1 W m(-3) at a current density of 6.9 A m(-3) were simultaneously achieved at an initial Cr (VI) concentration of 39.2 mg L(-1). Initial Cr (VI) concentration and solution conductivity affected Cr (VI) reduction rate, power production and coulombic efficiency. These findings demonstrate the importance of inoculation and MFC architecture in the enhancement of Cr (VI) reduction rate and power production. This study is a beneficial attempt to improve the efficiency of biocathode MFCs and provide a good candidate of bioremediation process for Cr (VI)-contaminated sites.

Preparation and biosorption evaluation of Bacillus subtilis/alginate–chitosan microcapsule

PubMed Central

Tong, Ke

2017-01-01

The aim of this study was to assess the effect of alginate–chitosan microcapsule on viability characteristics of Bacillus subtilis and the ability of B. subtilis/alginate–chitosan microcapsule to remove uranium ion from aqueous solution. The effects of particle size, chitosan molecular weight and inoculum density on viability characteristics were studied using alginate–chitosan microcapsule-immobilized B. subtilis experiments. In addition, the effects of pH, immobilized spherule dosage, temperature, initial uranium ion concentration and contact time on removal of uranium ion were studied using batch adsorption experiments. The results showed that alginate–chitosan microcapsule significantly improved the viability characteristics of B. subtilis and that B. subtilis/alginate–chitosan microcapsule strongly promoted uranium ion absorption. Moreover, the optimum values of pH was 6; immobilized spherule dosage was 3.5; temperature was 20°C; initial uranium ion concentration was 150 mg/L; contact time was 3 h of uranium ion absorption and the maximum adsorption capacity of uranium ion was 376.64 mg/g. PMID:28223783

The immunogenicity of recombinant vaccines based on modified Vaccinia Ankara (MVA) viruses expressing African horse sickness virus VP2 antigens depends on the levels of expressed VP2 protein delivered to the host.

PubMed

Calvo-Pinilla, Eva; Gubbins, Simon; Mertens, Peter; Ortego, Javier; Castillo-Olivares, Javier

2018-06-01

African horse sickness (AHS) is a lethal equine disease transmitted by Culicoides biting midges and caused by African horse sickness virus (AHSV). AHS is endemic to sub-Saharan Africa, but devastating outbreaks have been recorded periodically outside this region. The perceived risk of an AHS outbreak occurring in Europe has increased following the frequent epidemics caused in ruminants by bluetongue virus, closely related to AHSV. Attenuated vaccines for AHS are considered unsuitable for use in non-endemic countries due bio-safety concerns. Further, attenuated and inactivated vaccines are not compatible with DIVA (differentiate infected from vaccinated animals) strategies. All these factors stimulated the development of novel AHS vaccines that are safer, more efficacious and DIVA compatible. We showed previously that recombinant modified Vaccinia Ankara virus (MVA) vaccines encoding the outer capsid protein of AHSV (AHSV-VP2) induced virus neutralising antibodies (VNAb) and protection against AHSV in a mouse model and also in the horse. Passive immunisation studies demonstrated that immunity induced by MVA-VP2 was associated with pre-challenge VNAb titres in the vaccinates. Analyses of the inoculum of these MVA-VP2 experimental vaccines showed that they contained pre-formed AHSV-VP2. We continued studying the influence of pre-formed AHSV-VP2, present in the inoculum of MVA-VP2 vaccines, in the immunogenicity of MVA-VP2 vaccines. Thus, we compared correlates of immunity in challenged mice that were previously vaccinated with: a) MVA-VP2 (live); b) MVA-VP2 (live and sucrose gradient purified); c) MVA-VP2 (UV light inactivated); d) MVA-VP2 (UV light inactivated and diluted); e) MVA-VP2 (heat inactivated); f) MVA-VP2 (UV inactivated) + MVA-VP2 (purified); g) MVA-VP2 (heat inactivated) + MVA-VP2 (purified); and h) wild type-MVA (no insert). The results of these experiments showed that protection was maximal using MVA-VP2 (live) vaccine and that the protection conferred by all other vaccines correlated strongly with the levels of pre-formed AHSV-VP2 in the vaccine inoculum. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

[Production of a compost accelerator inoculant].

PubMed

Medina Lara, M Socorro; Quintero Lizaola, Roberto; Espinosa Victoria, David; Alarcón, Alejandro; Etchevers Barra, Jorge D; Trinidad Santos, Antonio; Conde Martínez, F Víctor

2017-10-26

Composting was performed using a mixture of ovine manure and straw. Inoculum was extracted at five different phases of the composting process (18, 23, 28, 33 and 38 days after the start of the composting process) and its effect on reducing biotransformation time was evaluated in the composted ovine manure. The samples were preserved in a deep freezer, then lyophilized to obtain the inoculum, 50g of which was added to each treatment in the second experimental phase. Six treatments were established; C=straw (P)+ovine manure (E), T1=P+ E+inoculum 18 days after the start of the composting process (I18), T2=P+E+I23, T3=P+E+I28, T4=P+E+I33, T5=P+E+I38, with three replications. Treatments were placed in a controlled-environment chamber at 45% relative humidity and 30°C along with flasks containing 50g of material to measure daily production, CO 2 accumulation, temperature, pH, electric conductivity (dS/m), organic matter (%), total nitrogen (%), total carbon (%), C: N ratio, particle size (Tp) and bulk density (g/l). CO 2 production (mg) showed a significant difference (p ≤.05) of treatments T2 and T5 with respect to the others, which demonstrated that the inoculum of these treatments accelerated the dynamics of microorganisms and the composting process. The quality and maturity of the compost are guaranteed as the amount of CO 2 decreases. Copyright © 2017 Asociación Argentina de Microbiología. Publicado por Elsevier España, S.L.U. All rights reserved.

Susceptibility screening of hyphae-forming fungi with a new, easy, and fast inoculum preparation method.

PubMed

Schmalreck, Arno; Willinger, Birgit; Czaika, Viktor; Fegeler, Wolfgang; Becker, Karsten; Blum, Gerhard; Lass-Flörl, Cornelia

2012-12-01

In vitro susceptibility testing of clinically important fungi becomes more and more essential due to the rising number of fungal infections in patients with impaired immune system. Existing standardized microbroth dilution methods for in vitro testing of molds (CLSI, EUCAST) are not intended for routine testing. These methods are very time-consuming and dependent on sporulating of hyphomycetes. In this multicentre study, a new (independent of sporulation) inoculum preparation method (containing a mixture of vegetative cells, hyphae, and conidia) was evaluated. Minimal inhibitory concentrations (MIC) of amphotericin B, posaconazole, and voriconazole of 180 molds were determined with two different culture media (YST and RPMI 1640) according to the DIN (Deutsches Institut für Normung) microdilution assay. 24 and 48 h MIC of quality control strains, tested per each test run, prepared with the new inoculum method were in the range of DIN. YST and RPMI 1640 media showed similar MIC distributions for all molds tested. MIC readings at 48 versus 24 h yield 1 log(2) higher MIC values and more than 90 % of the MICs read at 24 and 48 h were within ± 2 log(2) dilution. MIC end point reading (log(2 MIC-RPMI 1640)-log(2 MIC-YST)) of both media demonstrated a tendency to slightly lower MICs with RPMI 1640 medium. This study reports the results of a new, time-saving, and easy-to-perform method for inoculum preparation for routine susceptibility testing that can be applied for all types of spore-/non-spore and hyphae-forming fungi.

Enrichment and activity of methanotrophic microorganisms from municipal wastewater sludge.

PubMed

Siniscalchi, Luciene Alves Batista; Vale, Isabel Campante; Dell'Isola, Jéssica; Chernicharo, Carlos Augusto; Calabria Araujo, Juliana

2015-01-01

In this study, methanotrophic microorganisms were enriched from a municipal wastewater sludge taken from an Upflow Anaerobic Sludge Blanket reactor. The enrichment was performed in a sequencing batch reactor (SBR) with an autotrophic medium containing nitrite and nitrate. The microbial community composition of the inoculum and of the enrichment culture after 100 days of SBR operation was investigated and compared with the help of data obtained from 454 pyrosequencing analyses. The nitrite and nitrate removal efficiencies were 68% and 53%, respectively, probably due to heterotrophic denitrification. Archaeal cells of the anaerobic methanotrophic Archaic (ANME)-I and ANME-II groups were detected by polymerase chain reaction throughout the whole cultivation period. Pyrosequencing analysis showed that community composition was different among the two samples analysed. The dominant phyla found in the inoculum were Synergistestes, Firmicutes and Euryarchaeota, while Planctomycetes, Verrucomicrobia, Chloroflexi and Proteobacteria prevailed in the enriched biomass. The cultivation conditions decreased Methanobacterium abundance from 8% to 1%, and enriched for methanotrophic bacteria such as Methylocaldum, Methylocistis and Methylosinus. Sequences of Methylocaldum sp. accounted for 2.5% of the total reads. The presence and high predominance of Verrucomicrobia in the enriched biomass suggested that other unknown methanotrophic species related to that phylum might also have occurred in the reactor. Anaerobic methane oxidation activity was measured for both samples, and showed that the activity of the enrichment culture was nearly three times higher than the activity of the inoculum. Taken together, these results showed that the inoculum type and cultivation conditions were properly suited for methanotrophic enrichment.

Kinetics of methane production and biodegradation of linear alkylbenzene sulfonate from laundry wastewater.

PubMed

Motteran, Fabrício; Braga, Juliana K; Silva, Edson L; Varesche, Maria Bernadete A

2016-12-05

This study evaluates the kinetics of methane production and degradation of standard linear alkylbenzene sulfonate (LAS) (50 ± 3.5 mg/L) and LAS from laundry wastewater (85 ± 2.1 mg/L) in anaerobic batch reactors at 30°C with different sources of inoculum. The inocula were obtained by auto-fermentation (AFM) and UASB reactors from wastewater treatment of poultry slaughterhouse (SGH), swine production (SWT) and wastewater treatment thermophilic of sugarcane industry (THR). The study was divided into three phases: synthetic substrate (Phase I), standard LAS (Phase II) and LAS from laundry wastewater (Phase III). For SGH, the highest values for cumulative methane productions (1,844.8 ± 149 µmol-Phase II), methane production rate (70.8 ± 88 µmol/h-Phase II and 4.01 ± 07 µmol/h-Phase III) were observed. The use of thermophilic biomass (THR) incubated at 30°C was not favorable for methane production and LAS biodegradation, but the highest kinetic coefficient degradation (k 1 app ) was obtained for LAS (0.33 ± 0.3 h) compared with mesophilic biomass (SGH and SWT) (0.13 ± 0.02 h). Therefore, both LAS sources influenced the kinetics of methane production and organic matter degradation. For SGH, inoculum obtained the highest LAS degradation. In the SGH inoculum sequenced by MiSeq-Illumina was identified genera (VadinCA02, Candidatus Cloacamonas, VadinHB04, PD-UASB-13) related to degrade toxic compounds. Therefore, it recommended the reactor mesophilic inoculum UASB (SGH) for the LAS degradation.

Activation of inoculum microorganism from dairy cattle feces

NASA Astrophysics Data System (ADS)

Ayuningtyas, Widya D.; Ridwan, Roni; Joni, I. M.; Marlina, E. T.; Harlia, Ellin

2018-02-01

Coal produces Coal Bed Methane (CBM) which is formed both biogenically and thermogenically. Lignite is not utilized optimally because it has low heat content and productivity time limit that decreases CBM production. In order to utilize lignite waste, adding inoculum consortium microorganism from dairy cattle waste as starter for biogas process can be a solution. This study aimed to produce inoculum consortium microorganism as biogas starter from dairy cattle feces through in vitro activation process by Theoudorou modification method. The research used complete randomized design with 3 replications. The treatments were blank (R0), 100% concentrate (R1), 70% concentrate+30% grass (R2), 70% grass+30% concentrate (R3) and 100% grass (R4). All treatments were added by buffer solution and feces with ratio of 2:1 into 100 ml serum injection bottle with anaerobic conditions. The parameters observed were gas production, pH and gas kinetics (orskov's equation) for 2, 4, 6, 8, 10, 12, 24 and 48 hours. The results showed that the treatment had significant effect (P <0.05) on the observed parameters. The highest total gas production was for R2 and R3 treatments with total production of 91.17 ml and 101.17 ml, pH (6.62 and 6.57), maximum gas production (94.03 and 97.62 ml), speed of gas production (0.066 and 0.084 ml/hour). There is not a significant difference for both the treatments. The source of inoculum consortium microorganisms for biogas starter selected based on the observed parameters and potential availability of proteolytic and fibrocytic microorganisms is R2 (70% concentrate +30% grass).

Effect of biofumigation with brassica pellets combined with Brassicaceae cover crops and plastic cover on the survival and infectivity of inoculum of Phytophthora nicotianae Breda de Haan.

PubMed

Rodríguez-Molina, M Carmen; Serrano-Pérez, Paula; Palo, Carolina

2016-07-01

Biofumigation with defatted seed meal of Brassicaceae in the form of pellets has several advantages over the incorporation of fresh Brassicaceae crops to control soil-borne diseases. Two field experiments were established to evaluate the effect of biofumigation with brassica pellets on the survival and infectivity of Phytophthora nicotianae Breda de Haan inoculum introduced before treatments. In the spring experiment the incorporation of additional Brassicaceae cover crop (Brassica nigra L. and Sinapis alba L.) was tested, and in the summer experiment two brassica pellet doses were applied. Biofumigation with brassica pellets in spring (3000 kg ha(-1) with and without plastic) or in summer (3000 kg ha(-1) with or without plastic; 6000 kg ha(-1) without plastic) had no significant effect on the survival of P. nicotianae, regardless of the incorporation of additional Brassicaceae cover crop in spring. Reduction in infectivity in spring was related to the application of plastic, especially when combined with brassica pellets and Brassicaceae crop. In summer, soil temperature was the main factor in the inactivation of the inoculum, especially when plastic was applied, and no additional inactivation was achieved with brassica pellets. In spring and summer, biofumigation with brassica pellets had no effect on the survival of P. nicotianae. Application of plastic in spring may reduce infectivity. Soil temperature is the main factor in the inactivation of inoculum in summer, especially when plastic is applied. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

Induced Resistance to Meloidogyne hapla by other Meloidogyne species on Tomato and Pyrethrum Plants

PubMed Central

Ogallo, J. L.; McClure, M. A.

1995-01-01

Advance inoculation of the tomato cv. Celebrity or the pyrethrum clone 223 with host-incompatible Meloidogyne incognita or M. javanica elicited induced resistance to host-compatible M. hapla in pot and field experiments. Induced resistance increased with the length of the time between inoculations and with the population density of the induction inoculum. Optimum interval before challenge inoculation, or population density of inoculum for inducing resistance, was 10 days, or 5,000 infective nematodes per 500-cm³ pot. The induced resistance suppressed population increase of M. hapla by 84% on potted tomato, 72% on potted pyrethrum, and 55% on field-grown pyrethrum seedlings, relative to unprotected treatments. Pyrethrum seedlings inoculated with M. javanica 10 days before infection with M. hapla were not stunted, whereas those that did not receive the advance inoculum were stunted 33% in pots and 36% in field plots. The results indicated that advance infection of plants with incompatible or mildly virulent nematode species induced resistance to normally compatible nematodes and that the induced resistance response may have potential as a biological control method for plant nematodes. PMID:19277310

Bioremediation of diesel fuel contaminated soil: effect of non ionic surfactants and selected bacteria addition.

PubMed

Collina, Elena; Lasagni, Marina; Pitea, Demetrio; Franzetti, Andrea; Di Gennaro, Patrizia; Bestetti, Giuseppina

2007-09-01

Aim of this work was to evaluate influence of two commercial surfactants and inoculum of selected bacteria on biodegradation of diesel fuel in different systems. Among alkyl polyethossilates (Brij family) and sorbitan derivates (Tween family) a first selection of surfactants was performed by estimation of Koc and Dafnia magna EC50 with molecular descriptor and QSAR model. Further experiments were conducted to evaluate soil sorption, biodegradability and toxicity. In the second part of the research, the effect of Brij 56, Tween 80 and selected bacteria addition on biodegradation of diesel fuel was studied in liquid cultures and in slurry and solid phase systems. The latter experiments were performed with diesel contaminated soil in bench scale slurry phase bioreactor and solid phase columns. Tween 80 addition increased the biodegradation rate of hydrocarbons both in liquid and in slurry phase systems. Regarding the effect of inoculum, no enhancement of biodegradation rate was observed neither in surfactant added nor in experiments without addition. On the contrary, in solid phase experiments, inoculum addition resulted in enhanced biodegradation compared to surfactant addition.

Microbial structural diversity estimated by dilution-extinction of phenotypic traits and T-RFLP analysis along a land-use intensification gradient

NASA Technical Reports Server (NTRS)

Gomez, Elena del V.; Garland, Jay L.; Roberts, Michael S.

2004-01-01

The present work tested whether the relationship between functional traits and inoculum density reflected structural diversity in bacterial communities from a land-use intensification gradient applying a mathematical model. Terminal restriction fragment length polymorphism (T-RFLP) analysis was also performed to provide an independent assessment of species richness. Successive 10-fold dilutions of a soil suspension were inoculated onto Biolog GN(R) microplates. Soil bacterial density was determined by total cell and plate counts. The relationship between phenotypic traits and inoculum density fit the model, allowing the estimation of maximal phenotypic potential (Rmax) and inoculum density (KI) at which Rmax will be half-reduced. Though Rmax decreased with time elapsed since clearing of native vegetation, KI remained high in two of the disturbed sites. The genetic pool of bacterial community did not experience a significant reduction, but the active fraction responding in the Biolog assay was adversely affected, suggesting a reduction in the functional potential. c2004 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved.

Improvement of hydrogen fermentation of galactose by combined inoculation strategy.

PubMed

Sivagurunathan, Periyasamy; Anburajan, Parthiban; Kumar, Gopalakrishnan; Arivalagan, Pugazhendhi; Bakonyi, Péter; Kim, Sang-Hyoun

2017-03-01

This study evaluated the feasibility of anaerobic hydrogen fermentation of galactose, a red algal biomass sugar, using individual and combined mixed culture inocula. Heat-treated (90°C, 30 min) samples of granular sludge (GS) and suspended digester sludge (SDS) were used as inoculum sources. The type of mixed culture inoculum played an important role in hydrogen production from galactose. Between two inocula, granular sludge showed higher hydrogen production rate (HPR) and hydrogen yield (HY) of 2.2 L H 2 /L-d and 1.09 mol H 2 /mol galactose added , respectively. Combined inoculation (GS + SDS) led to an elevated HPR and HY of 3.1 L H 2 /L-d and 1.28 mol H 2 /mol galactose added , respectively. Acetic and butyric acids are the major organic acids during fermentation. Quantitative polymerase chain reaction (qPCR) revealed that the mixed culture generated using the combined inoculation contained a higher cluster I Clostridium abundance than the culture produced using the single inoculum. Copyright © 2016 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

[Effects of culture conditions on biomass and active components of adventitious roots culture in Panax ginseng].

PubMed

Huang, Tao; Gao, Wenyuan; Wang, Juan; Cao, Yu

2010-01-01

To optimize the culture condition of adventitious roots of Panax ginseng. The adventitious roots were obtained through tissue culture by manipulation of inoculum, various sucrose concentrations and salt strength. The contents of ginsenosides Re, Rb1 and Rg1 were determined by HPLC while the contents of polysaccharides were determined by ultraviolet spectrophotometry. The multiplication of adventitious roots reached the peak when the inoculum was 20 g x L(-1). The effects of sucrose concentration and salt strength on adventitious roots were observed. The contents of polysaccharides were higher when the medium contained more sucrose. 40 g x L(-1) sucrose was favorable for roots growth and biosynthesis of Re, while 30 g x L(-1) was favorable for the biosynthesis of Rb1 and Rg1. 3/4MS medium was benefit for the growth of adventitious roots and the biosynthesis of ginsenosides. The contents of polysaccharides were decreased with the increase of salt strength. The results showed that inoculum, various sucrose concentrations and salt strength have significant influences on adventitious roots growth, secondary metabolite and polysaccharide synthesis in P. ginseng.

Effects and optimization of the use of biochar in anaerobic digestion of food wastes.

PubMed

Cai, Jiao; He, Pinjing; Wang, Ying; Shao, Liming; Lü, Fan

2016-05-01

The addition of various amounts of biochar to anaerobic digestion of food wastes at different ratios of inoculum to substrate (ISR) was investigated to evaluate the effect of biochar as a functional additive and to optimize the additive dosage of biochar. The biochar treatments at ISR 2, 1, and 0.8 shortened the lag phase of digestion by -20.0%-10.9%, 43.3%-54.4%, and 36.3%-54.0%, and raised the maximum methane production rate by 100%-275%, 100%-133.3%, and 33.3%-100%, respectively, compared to control without biochar. Biochar also enhanced the degradation rate of dissolved organics and volatile fatty acids. Furthermore, the amount of biochar with best effectiveness at ISR = 2, 1, and 0.8 was 2.5, 0.625, and 0.5 g g(-1)-waste, respectively. Therefore, the effectiveness of biochar depended on the additive amount of biochar and at the same time the inoculum amount, implying a complementary role of abiotic biochar to biotic inoculum. © The Author(s) 2016.

Sequential batch thermophilic solid-state anaerobic digestion of lignocellulosic biomass via recirculating digestate as inoculum - Part II: Microbial diversity and succession.

PubMed

Lin, Long; Yu, Zhongtang; Li, Yebo

2017-10-01

This study aimed to investigate the effect of recirculation of digestate as inoculum on the microbial communities in thermophilic solid-state anaerobic digestion (SS-AD) of yard trimmings. The SS-AD consisted of 4 consecutive runs (30days/run), with digestate from the previous run being used as the inoculum of the subsequent run. Bacterial and archaeal communities (day 0, 4, 8, 12, 20, and 30) were examined using Illumina sequencing of 16S rRNA genes. The results revealed substantial microbial succession toward increased diversity until run 3. The proportions of Firmicutes that contained cellulolytic bacteria doubled, which might explain the concomitantly increased cellulose degradation and volatile fatty acids (VFAs). Clostridia and Thermotogae appeared to correlate with VFAs. The VFA accumulation likely induced dynamic shifts of methanogens, particularly to hydrogenotrophic Methanothermobacter, implying that non-acetoclastic oxidative pathway dominated during the steady-state thermophilic SS-AD. This study suggested that recirculating SS-AD digestate might be an effective way for inoculation. Copyright © 2017 Elsevier Ltd. All rights reserved.

A new bioseed for determination of wastewater biodegradability: analysis of the experimental procedure.

PubMed

Ballesteros Martín, M M; Esteban García, B; Ortega-Gómez, E; Sánchez Pérez, J A

2014-01-01

A new bioassay proposed in the patent P201300029 was applied to a pre-treated wastewater containing a mixture of commercial pesticides to simulate a recalcitrant industrial wastewater in order to determine its biodegradability. The test uses a mixture of standardized inoculum of the lyophilized bacteria Pseudomonas putida with the proper proportion of salts and minerals. The results highlight that biodegradation efficiency can be calculated using a gross parameter (chemical oxygen demand (COD)) which facilitates the biodegradability determination for routine water biodegradability analysis. The same trend was observed throughout the assay with the dehydrated and fresh inoculums, and only a difference of 5% in biodegradation efficiency (E f) was observed. The obtained results showed that the P. putida biodegradability assay can be used as a commercial test with a lyophilized inoculum in order to monitor the ready biodegradability of an organic pollutant or a WWTP influent. Moreover, a combination of the BOD5/COD ratio and the P. putida biodegradability test is an attractive alternative in order to evaluate the biodegradability enhancement in water pre-treated with advanced oxidation processes (AOPs).

Inhibitory activity of Paenibacillus polymyxa on the biofilm formation of Cronobacter spp. on stainless steel surfaces.

PubMed

Yang, Soonwook; Kim, Seonhwa; Ryu, Jee-Hoon; Kim, Hoikyung

2013-07-01

The objective of this study was to control the survival or biofilm formation of Cronobacter spp. on stainless steel surfaces using Paenibacillus polymyxa. The antibacterial activity of a cell-free culture supernatant (CFCS) of P. polymyxa against Cronobacter spp. was found to vary with P. polymyxa incubation time. Maximum activity occurred when P. polymyxa was incubated at 25 or 30 °C for 96 h. When the CFCS was introduced to Cronobacter spp. adhered to stainless steel strips at 25 °C for up to 72 h, the CFCS successfully inhibited Cronobacter biofilm formation. Additionally, stainless steel surfaces with a preformed P. polymyxa biofilm were exposed to Cronobacter spp. suspensions in PBS or 0.1% peptone water at 3, 5, or 7 log CFU/mL to facilitate its attachment. The Cronobacter population significantly decreased on this surface, regardless of inoculum level or carrier, when the P. polymyxa biofilm was present. However, the microbial population decreased within 6 h and remained unchanged thereafter when the surface was immersed in an inoculum suspended in 0.1% peptone water at 5 or 7 log CFU/mL. These results indicate that P. polymyxa is able to use a promising candidate competitive-exclusion microorganism to control Cronobacter spp. © 2013 Institute of Food Technologists®

Optimization of Crude Oil and PAHs Degradation by Stenotrophomonas rhizophila KX082814 Strain through Response Surface Methodology Using Box-Behnken Design

PubMed Central

Virupakshappa, Praveen Kumar Siddalingappa; Mishra, Gaurav; Mehkri, Mohammed Ameenuddin

2016-01-01

The present paper describes the process optimization study for crude oil degradation which is a continuation of our earlier work on hydrocarbon degradation study of the isolate Stenotrophomonas rhizophila (PM-1) with GenBank accession number KX082814. Response Surface Methodology with Box-Behnken Design was used to optimize the process wherein temperature, pH, salinity, and inoculum size (at three levels) were used as independent variables and Total Petroleum Hydrocarbon, Biological Oxygen Demand, and Chemical Oxygen Demand of crude oil and PAHs as dependent variables (response). The statistical analysis, via ANOVA, showed coefficient of determination R 2 as 0.7678 with statistically significant P value 0.0163 fitting in second-order quadratic regression model for crude oil removal. The predicted optimum parameters, namely, temperature, pH, salinity, and inoculum size, were found to be 32.5°C, 9, 12.5, and 12.5 mL, respectively. At this optimum condition, the observed and predicted PAHs and crude oil removal were found to be 71.82% and 79.53% in validation experiments, respectively. The % TPH results correlate with GC/MS studies, BOD, COD, and TPC. The validation of numerical optimization was done through GC/MS studies and % removal of crude oil. PMID:28116165

Microbial communities in liquid and fiber fractions of food waste digestates are differentially resistant to inhibition by ammonia.

PubMed

Peng, Wei; Lü, Fan; Shao, Liming; He, Pinjing

2015-04-01

The effect of different concentrations of ammonia (1.0-7.0 g/L) during mesophilic anaerobic digestion with fiber or liquid digestate as inoculum was examined. Evolution of microbial community within fiber and liquid digestates was quantitatively assessed by the intact lipid analysis methods and qualitatively by DNA fingerprint methods in order to determine their resistance to ammonia inhibition. The results showed that an increased level of total ammonia nitrogen prolonged the lag phase of fiber digestates while reduced the metabolic rate of liquid digestates. Fiber digestates had 19.6-50.9-fold higher concentrations of phospholipid fatty acids (PLFA) compared to liquid digestates, whereas concentrations of phospholipid ether lipids (PLEL) in the fiber digestates were only 2.91-17.6-fold higher compared to liquid digestates. Although the cell concentration in liquid fraction was far lower than that in the fiber one, the ammonia-resistant ability and the methanization efficiency of the liquid digestate was superior to the fiber digestate. The bacterial profiles were affected more by the type of digestate inoculum compared to the concentration of ammonia. Principal component analysis indicated that the lipids technique was superior to the DNA technique for bacterial quantification but detected less archaeal diversity.

Effect of Pseudomonas sp. HF-1 inoculum on construction of a bioaugmented system for tobacco wastewater treatment: analysis from quorum sensing.

PubMed

Wang, Mei-Zhen; He, Hong-Zhen; Zheng, Xin; Feng, Hua-Jun; Lv, Zhen-Mei; Shen, Dong-Sheng

2014-01-01

To better construct a bioaugmented system for tobacco wastewater treatment, activated sludge was inoculated with different concentrations of the nicotine-degrading bacterium Pseudomonas sp. HF-1. The results showed that inoculum concentrations of 0.55 ± 0.01 and 1.10 ± 0.03 mg/g (dry weight of strain HF-1/dry weight of activated sludge) were best to ensure strain HF-1 survival and successful bioaugmentation. The release pattern of autoinducer (AI) for quorum sensing in the bioaugmented system was also investigated. During the period of HF-1 inoculation, compared with failed bioaugmented systems, AI-2 was significantly increased in the successful systems, suggesting that AI-2-mediated bacterial communication played an important role in the colonization of HF-1. When inoculation of strain HF-1 was stopped, the amount of AI-2 decreased and leveled out in all systems. Notably, there was a greater than threefold increase of short-chain AHLs in failed bioaugmented systems, but no increase in successful ones, implying that the fluctuation of short-chain AHLs could be an indicator of the failure of bioaugmentation. Thus, AI-2-mediated quorum sensing could be implemented to facilitate HF-1 colonization.

Bile-Esculin Test for Presumptive Identification of Enterococci and Streptococci: Effects of Bile Concentration, Inoculation Technique, and Incubation Time

PubMed Central

Chuard, C.; Reller, L. B.

1998-01-01

The bile-esculin test is used to differentiate enterococci and group D streptococci from non-group D viridans group streptococci. The effects on test performance of the concentration of bile salts, inoculum, and duration of incubation were examined with 110 strains of enterococci, 30 strains of Streptococcus bovis, and 110 strains of non-group D viridans group streptococci. Optimal sensitivity (>99%) and specificity (97%) of the bile-esculin test can be obtained with a bile concentration of 40%, a standardized inoculum of 106 CFU, and incubation for 24 h. PMID:9542954

Bile-esculin test for presumptive identification of enterococci and streptococci: effects of bile concentration, inoculation technique, and incubation time.

PubMed

Chuard, C; Reller, L B

1998-04-01

The bile-esculin test is used to differentiate enterococci and group D streptococci from non-group D viridans group streptococci. The effects on test performance of the concentration of bile salts, inoculum, and duration of incubation were examined with 110 strains of enterococci, 30 strains of Streptococcus bovis, and 110 strains of non-group D viridans group streptococci. Optimal sensitivity (> 99%) and specificity (97%) of the bile-esculin test can be obtained with a bile concentration of 40%, a standardized inoculum of 10(6) CFU, and incubation for 24 h.

RT-SHIV subpopulation dynamics in infected macaques during anti-HIV therapy

PubMed Central

2009-01-01

Background To study the dynamics of wild-type and drug-resistant HIV-1 RT variants, we developed a methodology that follows the fates of individual genomes over time within the viral quasispecies. Single genome sequences were obtained from 3 pigtail macaques infected with a recombinant simian immunodeficiency virus containing the RT coding region from HIV-1 (RT-SHIV) and treated with short-course efavirenz monotherapy 13 weeks post-infection followed by daily combination antiretroviral therapy (ART) beginning at week 17. Bioinformatics tools were constructed to trace individual genomes from the beginning of infection to the end of the treatment. Results A well characterized challenge RT-SHIV inoculum was used to infect three monkeys. The RT-SHIV inoculum had 9 variant subpopulations and the dominant subpopulation accounted for 80% of the total genomes. In two of the three monkeys, the inoculated wild-type virus was rapidly replaced by new wild type variants. By week 13, the original dominant subpopulation in the inoculum was replaced by new dominant subpopulations, followed by emergence of variants carrying known NNRTI resistance mutations. However, during ART, virus subpopulations containing resistance mutations did not outgrow the wide-type subpopulations until a minor subpopulation carrying linked drug resistance mutations (K103N/M184I) emerged. We observed that persistent viremia during ART is primarily made up of wild type subpopulations. We also found that subpopulations carrying the V75L mutation, not known to be associated with NNRTI resistance, emerged initially in week 13 in two macaques. Eventually, all subpopulations from these two macaques carried the V75L mutation. Conclusion This study quantitatively describes virus evolution and population dynamics patterns in an animal model. The fact that wild type subpopulations remained as dominant subpopulations during ART treatment suggests that the presence or absence of at least some known drug resistant mutations may not greatly affect virus replication capacity in vivo. Additionally, the emergence and prevalence of V75L indicates that this mutation may provide the virus a selective advantage, perhaps escaping the host immure system surveillance. Our new method to quantitatively analyze viral population dynamics enabled us to observe the relative competitiveness and adaption of different viral variants and provided a valuable tool for studying HIV subpopulation emergence, persistence, and decline during ART. PMID:19889213

Shoot δ(15)N and δ (13)C values of non-host Brassica rapa change when exposed to ±Glomus etunicatum inoculum and three levels of phosphorus and nitrogen.

PubMed

Fonseca, Henrique M; Berbara, Ricardo L; Daft, Melvin J

2001-08-01

Glasshouse experiments were conducted to study the response of non-host Brassica rapa and host Sorghum bicolor to inoculation with the arbuscular mycorrhizal fungus (AMF) Glomus etunicatum when given different levels of N (0.9 mmol kg(-1) sand, 2.7 mmol kg(-1) sand, 8.1 mmol kg(-1) sand) and P (3.6 µmol kg(-1) sand, 10.7 µmol kg(-1) sand, 32.0 µmol kg(-1) sand) fertiliser. On both plant species, the presence of G. etunicatum inoculum (+AMF) was associated with significant changes of shoot δ(15)N values, with +AMF plants having larger average δ(15)N values than uninoculated plants (-AMF). These values are the largest average differences in shoot δ(15)N yet recorded for AMF and nutrient effects. B. rapa shoot δ(15)N average differences ranged from 1.67‰ to 2.70‰, while for S. bicolor they range between 2.07‰ and 4.40‰. For shoot δ(13)C only the non-host B. rapa responded to ±AMF and added N. Although the harvested dry weight biomass (-35.2% B. rapa; +39.8% S. bicolor) of both plant species responded to AMF inoculation, no direct relationship was observed between isotopic discrimination and growth inhibition for the non-host B. rapa. In this paper we discuss some implications regarding AMF inocula on the basis of our findings and current literature.

Convergent development of anodic bacterial communities in microbial fuel cells.

PubMed

Yates, Matthew D; Kiely, Patrick D; Call, Douglas F; Rismani-Yazdi, Hamid; Bibby, Kyle; Peccia, Jordan; Regan, John M; Logan, Bruce E

2012-11-01

Microbial fuel cells (MFCs) are often inoculated from a single wastewater source. The extent that the inoculum affects community development or power production is unknown. The stable anodic microbial communities in MFCs were examined using three inocula: a wastewater treatment plant sample known to produce consistent power densities, a second wastewater treatment plant sample, and an anaerobic bog sediment. The bog-inoculated MFCs initially produced higher power densities than the wastewater-inoculated MFCs, but after 20 cycles all MFCs on average converged to similar voltages (470±20 mV) and maximum power densities (590±170 mW m(-2)). The power output from replicate bog-inoculated MFCs was not significantly different, but one wastewater-inoculated MFC (UAJA3 (UAJA, University Area Joint Authority Wastewater Treatment Plant)) produced substantially less power. Denaturing gradient gel electrophoresis profiling showed a stable exoelectrogenic biofilm community in all samples after 11 cycles. After 16 cycles the predominance of Geobacter spp. in anode communities was identified using 16S rRNA gene clone libraries (58±10%), fluorescent in-situ hybridization (FISH) (63±6%) and pyrosequencing (81±4%). While the clone library analysis for the underperforming UAJA3 had a significantly lower percentage of Geobacter spp. sequences (36%), suggesting that a predominance of this microbe was needed for convergent power densities, the lower percentage of this species was not verified by FISH or pyrosequencing analyses. These results show that the predominance of Geobacter spp. in acetate-fed systems was consistent with good MFC performance and independent of the inoculum source.

Development of a quantitative loop-mediated isothermal amplification assay for the field detection of Erysiphe necator.

PubMed

Thiessen, Lindsey D; Neill, Tara M; Mahaffee, Walter F

2018-01-01

Plant pathogen detection systems have been useful tools to monitor inoculum presence and initiate management schedules. More recently, a loop-mediated isothermal amplification (LAMP) assay was successfully designed for field use in the grape powdery mildew pathosystem; however, false negatives or false positives were prevalent in grower-conducted assays due to the difficulty in perceiving the magnesium pyrophosphate precipitate at low DNA concentrations. A quantitative LAMP (qLAMP) assay using a fluorescence resonance energy transfer-based probe was assessed by grape growers in the Willamette Valley of Oregon. Custom impaction spore samplers were placed at a research vineyard and six commercial vineyard locations, and were tested bi-weekly by the lab and by growers. Grower-conducted qLAMP assays used a beta-version of the Smart-DART handheld LAMP reaction devices (Diagenetix, Inc., Honolulu, HI, USA), connected to Android 4.4 enabled, Bluetooth-capable Nexus 7 tablets for output. Quantification by a quantitative PCR assay was assumed correct to compare the lab and grower qLAMP assay quantification. Growers were able to conduct and interpret qLAMP results; however, the Erysiphe necator inoculum quantification was unreliable using the beta-Smart-DART devices. The qLAMP assay developed was sensitive to one spore in early testing of the assay, but decreased to >20 spores by the end of the trial. The qLAMP assay is not likely a suitable management tool for grape powdery mildew due to losses in sensitivity and decreasing costs and portability for other, more reliable molecular tools.

Model Study To Assess Softwood Hemicellulose Hydrolysates as the Carbon Source for PHB Production in Paraburkholderia sacchari IPT 101.

PubMed

Dietrich, Karolin; Dumont, Marie-Josée; Schwinghamer, Timothy; Orsat, Valérie; Del Rio, Luis F

2018-01-08

Softwood hemicellulose hydrolysates are a cheap source of sugars that can be used as a feedstock to produce polyhydroxybutyrates (PHB), which are biobased and compostable bacterial polyesters. To assess the potential of the hemicellulosic sugars as a carbon source for PHB production, synthetic media containing softwood hemicellulose sugars (glucose, mannose, galactose, xylose, arabinose) and the potentially inhibitory lignocellulose degradation products (acetic acid, 5-hydroxymethylfurfural (HMF), furfural, and vanillin) were fermented with the model strain Paraburkholderia sacchari IPT 101. Relative to pure glucose, individual fermentation for 24 h with 20 g/L mannose or galactose exhibited maximum specific growth rates of 97% and 60%, respectively. On the other hand, with sugar mixtures of glucose, mannose, galactose, xylose, and arabinose, the strain converted all sugars simultaneously to reach a maximum PHB concentration of 5.72 g/L and 80.5% PHB after 51 h. The addition of the inhibitor mixture at the following concentration, sodium acetate (2.11 g/L), HMF (0.67 g/L), furfural (0.66 g/L), and vanillin (0.93 g/L), to the sugar mixture stopped the growth entirely within 24 h. Individually, the inhibitors either had no effect or only reduced growth. Moreover, it was found that a bacterial inoculum with high initial cell density (optical density, OD ≥ 5.6) could overcome the growth inhibition to yield an OD of 13 within 24 h. Therefore, softwood hemicellulose sugars are viable carbon sources for PHB production. Nevertheless, real softwood hemicellulose hydrolysates need detoxification or a high inoculum to overcome inhibitory effects and allow bacterial growth.

Host and Cropping System Shape the Fusarium Population: 3ADON-Producers Are Ubiquitous in Wheat Whereas NIV-Producers Are More Prevalent in Rice.

PubMed

Yang, Meixin; Zhang, Hao; Kong, Xiangjiu; van der Lee, Theo; Waalwijk, Cees; van Diepeningen, Anne; Xu, Jin; Xu, Jingsheng; Chen, Wanquan; Feng, Jie

2018-03-08

In recent years, Fusarium head blight (FHB) outbreaks have occurred much more frequently in China. The reduction of burning of the preceding crop residues is suggested to contribute to more severe epidemics as it may increase the initial inoculum. In this study, a large number of Fusarium isolates was collected from blighted wheat spikes as well as from rice stubble with perithecia originating from nine sampling sites in five provinces in Southern China. Fusarium asiaticum dominated both wheat and rice populations, although rice populations showed a higher species diversity. Chemotype analysis showed that rice is the preferred niche for NIV mycotoxin producers that were shown to be less virulent on wheat. In contrast, 3ADON producers are more prevalent on wheat and in wheat producing areas. The 3ADON producers were shown to be more virulent on wheat, revealing the selection pressure of wheat on 3ADON producers. For the first time, members of the Incarnatum -clade of Fusarium Incarnatum - Equiseti Species Complex (FIESC) were found to reproduce sexually on rice stubble. The pathogenicity of FIESC isolates on wheat proved very low and this may cause the apparent absence of this species in the main wheat producing provinces. This is the first report of the Fusarium population structure including rice stubble as well as a direct comparison with the population on wheat heads in the same fields. Our results confirm that the perithecia on rice stubble are the primary inoculum of FHB on wheat and that cropping systems affect the local Fusarium population.

Production of paclitaxel with anticancer activity by two local fungal endophytes, Aspergillus fumigatus and Alternaria tenuissima.

PubMed

Ismaiel, Ahmed A; Ahmed, Ashraf S; Hassan, Ismail A; El-Sayed, El-Sayed R; Karam El-Din, Al-Zahraa A

2017-07-01

Among 60 fungal endophytes isolated from twigs, bark, and mature leaves of different plant species, two fungal isolates named TXD105 and TER995 were capable of producing paclitaxel in amounts of up to 84.41 and 37.92 μg L -1 , respectively. Based on macroscopic and microscopic characteristics, ITS1-5.8S-ITS2 rDNA sequence, and phylogenetic characteristic analysis, the two respective isolates were identified as Aspergillus fumigatus and Alternaria tenuissima. In the effort to increase paclitaxel magnitude by the two fungal strains, several fermentation conditions including selection of the proper fermentation medium, agitation rate, incubation temperature, fermentation period, medium pH, medium volume, and inoculum nature (size and age of inoculum) were tried. Fermentation process carried out in M1D medium (pH 6.0) and maintained at 120 rpm for 10 days and at 25 °C using 4% (v/v) inoculum of 5-day-old culture stimulated the highest paclitaxel production to attain 307.03 μg L -1 by the A. fumigatus strain. In the case of the A. tenuissima strain, fermentation conditions conducted in flask basal medium (pH 6.0) and maintained at 120 rpm for 14 days and at 25 °C using 8% (v/v) inoculum of 7-day-old culture were found the most favorable to attain the highest paclitaxel production of 124.32 μg L -1 . Using the MTT-based assay, fungal paclitaxel significantly inhibited the proliferation of five different cancer cell lines with 50% inhibitory concentration values varied from 3.04 to 14.8 μg mL -1 . Hence, these findings offer new and alternate sources with excellent biotechnological potential for paclitaxel production by fungal fermentation.

Litter quality versus soil microbial community controls over decomposition: a quantitative analysis

USGS Publications Warehouse

Cleveland, Cory C.; Reed, Sasha C.; Keller, Adrienne B.; Nemergut, Diana R.; O'Neill, Sean P.; Ostertag, Rebecca; Vitousek, Peter M.

2014-01-01

The possible effects of soil microbial community structure on organic matter decomposition rates have been widely acknowledged, but are poorly understood. Understanding these relationships is complicated by the fact that microbial community structure and function are likely to both affect and be affected by organic matter quality and chemistry, thus it is difficult to draw mechanistic conclusions from field studies. We conducted a reciprocal soil inoculum × litter transplant laboratory incubation experiment using samples collected from a set of sites that have similar climate and plant species composition but vary significantly in bacterial community structure and litter quality. The results showed that litter quality explained the majority of variation in decomposition rates under controlled laboratory conditions: over the course of the 162-day incubation, litter quality explained nearly two-thirds (64 %) of variation in decomposition rates, and a smaller proportion (25 %) was explained by variation in the inoculum type. In addition, the relative importance of inoculum type on soil respiration increased over the course of the experiment, and was significantly higher in microcosms with lower litter quality relative to those with higher quality litter. We also used molecular phylogenetics to examine the relationships between bacterial community composition and soil respiration in samples through time. Pyrosequencing revealed that bacterial community composition explained 32 % of the variation in respiration rates. However, equal portions (i.e., 16 %) of the variation in bacterial community composition were explained by inoculum type and litter quality, reflecting the importance of both the meta-community and the environment in bacterial assembly. Taken together, these results indicate that the effects of changing microbial community composition on decomposition are likely to be smaller than the potential effects of climate change and/or litter quality changes in response to increasing atmospheric CO2 concentrations or atmospheric nutrient deposition.

Crop connectivity under climate change: future environmental and geographic risks of potato late blight in Scotland.

PubMed

Skelsey, Peter; Cooke, David E L; Lynott, James S; Lees, Alison K

2016-11-01

The impact of climate change on dispersal processes is largely ignored in risk assessments for crop diseases, as inoculum is generally assumed to be ubiquitous and nonlimiting. We suggest that consideration of the impact of climate change on the connectivity of crops for inoculum transmission may provide additional explanatory and predictive power in disease risk assessments, leading to improved recommendations for agricultural adaptation to climate change. In this study, a crop-growth model was combined with aerobiological models and a newly developed infection risk model to provide a framework for quantifying the impact of future climates on the risk of disease occurrence and spread. The integrated model uses standard meteorological variables and can be easily adapted to various crop pathosystems characterized by airborne inoculum. In a case study, the framework was used with data defining the spatial distribution of potato crops in Scotland and spatially coherent, probabilistic climate change data to project the future connectivity of crop distributions for Phytophthora infestans (causal agent of potato late blight) inoculum and the subsequent risk of infection. Projections and control recommendations are provided for multiple combinations of potato cultivar and CO 2 emissions scenario, and temporal and spatial averaging schemes. Overall, we found that relative to current climatic conditions, the risk of late blight will increase in Scotland during the first half of the potato growing season and decrease during the second half. To guide adaptation strategies, we also investigated the potential impact of climate change-driven shifts in the cropping season. Advancing the start of the potato growing season by 1 month proved to be an effective strategy from both an agronomic and late blight management perspective. © 2016 John Wiley & Sons Ltd.

Effects of Growth Medium, Inoculum Size, and Incubation Time on Culturability and Isolation of Soil Bacteria

PubMed Central

Davis, Kathryn E. R.; Joseph, Shayne J.; Janssen, Peter H.

2005-01-01

Soils are inhabited by many bacteria from phylogenetic groups that are poorly studied because representatives are rarely isolated in cultivation studies. Part of the reason for the failure to cultivate these bacteria is the low frequency with which bacterial cells in soil form visible colonies when inoculated onto standard microbiological media, resulting in low viable counts. We investigated the effects of three factors on viable counts, assessed as numbers of CFU on solid media, and on the phylogenetic groups to which the isolated colony-forming bacteria belong. These factors were inoculum size, growth medium, and incubation time. Decreasing the inoculum size resulted in significant increases in the viable count but did not appear to affect colony formation by members of rarely isolated groups. Some media that are traditionally used for soil microbiological studies returned low viable counts and did not result in the isolation of members of rarely isolated groups. Newly developed media, in contrast, resulted in high viable counts and in the isolation of many members of rarely isolated groups, regardless of the inoculum size. Increased incubation times of up to 3 months allowed the development of visible colonies of members of rarely isolated groups in conjunction with the use of appropriate media. Once isolated, pure cultures of members of rarely isolated groups took longer to form visible colonies than did members of commonly isolated groups. Using these new media and extended incubation times, we were able to isolate many members of the phyla Acidobacteria (subdivisions 1, 2, 3, and 4), Gemmatimonadetes, Chloroflexi, and Planctomycetes (including representatives of the previously uncultured WPS-1 lineage) as well as members of the subclasses Rubrobacteridae and Acidimicrobidae of the phylum Actinobacteria. PMID:15691937

Antimicrobial Properties of Selected Copper Alloys on Staphylococcus aureus and Escherichia coli in Different Simulations of Environmental Conditions: With vs. without Organic Contamination.

PubMed

Różańska, Anna; Chmielarczyk, Agnieszka; Romaniszyn, Dorota; Sroka-Oleksiak, Agnieszka; Bulanda, Małgorzata; Walkowicz, Monika; Osuch, Piotr; Knych, Tadeusz

2017-07-20

Background: Hospital equipment made from copper alloys can play an important role in complementing traditional methods of disinfection. Aims of the study: The aim of this study was to assess the dynamics of the antimicrobial properties of selected copper alloys in different simulations of environmental conditions (with organic contamination vs. without organic contamination), and to test alternatives to the currently used testing methods. Materials and Methods: A modification of Japanese standard JIS Z 2801 as well as Staphylococcus aureus (SA) and Escherichia coli (EC) suspended in NaCl vs. tryptic soy broth (TSB) were used in tests performed on seven commonly used copper alloys, copper, and stainless steel. Results: A much faster reduction of the bacterial suspension was observed for the inoculum prepared in NaCl than in TSB. A faster reduction for EC than for SA was observed in the inoculum prepared in NaCl. The opposite results were found for the inoculum based on TSB. A significant correlation between the copper concentration in the copper alloys and the time and degree of bacterial suspension reduction was only observed in the case of EC. Conclusions: This study confirmed the antimicrobial properties of copper alloys, and additionally showed that Staphylococcus aureus was more resistant than Escherichia coli in the variant of the experiment without organic contamination. However, even for SA, a total reduction of the bacterial inoculum's density took no longer than 2 h. Under conditions simulating organic contamination, all of the tested alloys were shown to have bactericidal or bacteriostatic properties, which was contrary to the results from stainless steel.

Effectiveness of lemon juice in the elimination of Salmonella Typhimurium in stuffed mussels.

PubMed

Kişla, Duygu

2007-12-01

Street foods are becoming more and more prominent in countries all over the world. There are many reports of disease due to consumption of street foods contaminated by pathogens. With the modern trend toward more natural preservatives, the use of organic acids can achieve a good microbiological safety in food. In the present study, stuffed mussels were inoculated with Salmonella Typhimurium suspension to provide initial populations of approximately 6 and 3 log CFU/g. After inoculation, samples were treated with fresh lemon juice and lemon dressing for 0, 5, and 15 min, and pathogens were enumerated by using direct plating on brilliant green agar. Treatment of stuffed mussels inoculated at high inoculum level, with lemon juice and lemon dressing for different exposure times caused reduction ranging between 0.25 and 0.56 log CFU/g and 0.5 and 0.69 log CFU/g, respectively, whereas in stuffed-mussel samples inoculated at low level, lemon juice and lemon dressing caused 0.08 to 0.25 log CFU/g and 0.22 to 0.78 log CFU/g reductions, respectively. Results of the study showed that both lemon juice and lemon dressing used as flavoring and acidifying agents for stuffed mussels caused slight decrease in Salmonella Typhimurium as an immediate inhibitor, but this effect increased by time. However, treatment of stuffed mussels with the inhibitors until 15 min is not enough to prevent Salmonella Typhimurium outbreaks related to stuffed mussels.

Modeling the impact of the indigenous microbial population on the maximum population density of Salmonella on alfalfa.

PubMed

Rijgersberg, Hajo; Franz, Eelco; Nierop Groot, Masja; Tromp, Seth-Oscar

2013-07-01

Within a microbial risk assessment framework, modeling the maximum population density (MPD) of a pathogenic microorganism is important but often not considered. This paper describes a model predicting the MPD of Salmonella on alfalfa as a function of the initial contamination level, the total count of the indigenous microbial population, the maximum pathogen growth rate and the maximum population density of the indigenous microbial population. The model is parameterized by experimental data describing growth of Salmonella on sprouting alfalfa seeds at inoculum size, native microbial load and Pseudomonas fluorescens 2-79. The obtained model fits well to the experimental data, with standard errors less than ten percent of the fitted average values. The results show that the MPD of Salmonella is not only dictated by performance characteristics of Salmonella but depends on the characteristics of the indigenous microbial population like total number of cells and its growth rate. The model can improve the predictions of microbiological growth in quantitative microbial risk assessments. Using this model, the effects of preventive measures to reduce pathogenic load and a concurrent effect on the background population can be better evaluated. If competing microorganisms are more sensitive to a particular decontamination method, a pathogenic microorganism may grow faster and reach a higher level. More knowledge regarding the effect of the indigenous microbial population (size, diversity, composition) of food products on pathogen dynamics is needed in order to make adequate predictions of pathogen dynamics on various food products.

Evaluation of VIDAS UP Listeria assay (LPT) for the detection of Listeria in a variety of foods and environmental surfaces: First Action 2013.10.

PubMed

Crowley, Erin; Bird, Patrick; Flannery, Jonathan; Benzinger, M Joseph; Fisher, Kiel; Boyle, Megan; Huffman, Travis; Bastin, Ben; Bedinghaus, Paige; Judd, William; Hoang, Thao; Agin, James; Goins, David; Johnson, Ronald L

2014-01-01

The VIDAS UP Listeria (LPT) is an automated rapid screening enzyme phage-ligand based assay for the detection of Listeria species in human food products and environmental samples. The VIDAS LPT method was compared in a multi-laboratory collaborative study to AOAC Official Method 993.12 Listeria monocytogenes in Milk and Dairy Products reference method following current AOAC guidelines. A total of 14 laboratories participated, representing government and industry, throughout the United States. One matrix, queso fresco (soft Mexican cheese), was analyzed using two different test portion sizes, 25 and 125 g. Samples representing each test portion size were artificially contaminated with Listeria species at three levels, an uninoculated control level [0 colony-forming units (CFU)/test portion], a low-inoculum level (0.2-2 CFU/test portion), and a high-inoculum level (2-5 CFU/test portion). For this evaluation, 1800 unpaired replicate test portions were analyzed by either the VIDAS LPT or AOAC 993.12. Each inoculation level was analyzed using the Probability of Detection (POD) statistical model. For the low-level inoculated test portions, difference in collaborator POD (dLPOD) values of 0.01, (-0.10, 0.13), with 95% confidence intervals, were obtained for both 25 and 125 g test portions. The range of the confidence intervals for dLPOD values for both the 25 and 125 g test portions contains the point 0.0 indicating no statistically significant difference in the number of positive samples detected between the VIDAS LPT and the AOAC methods. In addition to Oxford agar, VIDAS LPT test portions were confirmed using Agar Listeria Ottavani and Agosti (ALOA), a proprietary chromogenic agar for the identification and differentiation of L. monocytogenes and Listeria species. No differences were observed between the two selective agars. The VIDAS LPT method, with the optional ALOA agar confirmation method, was adopted as Official First Action status for the detection of Listeria species in a variety of foods and environmental samples.

Evaluation of Modification of the 3M™ Molecular Detection Assay (MDA) Salmonella Method (2013.09) for the Detection of Salmonella in Selected Foods: Collaborative Study.

PubMed

Bird, Patrick; Fisher, Kiel; Boyle, Megan; Huffman, Travis; Benzinger, M Joseph; Bedinghaus, Paige; Flannery, Jonathon; Crowley, Erin; Agin, James; Goins, David; Benesh, DeAnn; David, John

2014-01-01

The 3M(™) Molecular Detection Assay (MDA) Salmonella utilizes isothermal amplification of nucleic acid sequences with high specificity, efficiency, rapidity and bioluminescence to detect amplification of Salmonella spp. in food, food-related, and environmental samples after enrichment. A method modification and matrix extension study of the previously approved AOAC Official Method(SM) 2013.09 was conducted, and approval of the modification was received on March 20, 2014. Using an unpaired study design in a multilaboratory collaborative study, the 3M MDA Salmonella method was compared to the U.S. Department of Agriculture/Food Safety and Inspection Service (USDA/FSIS) Microbiology Laboratory Guidebook (MLG) 4.05 (2011), Isolation and Identification of Salmonella from Meat, Poultry, Pasteurized Egg, and Catfish Products for raw ground beef and the U.S. Food and Drug Administration (FDA)/Bacteriological Analytical Manual (BAM) Chapter 5, Salmonella reference method for wet dog food following the current AOAC guidelines. A total of 20 laboratories participated. For the 3M MDA Salmonella method, raw ground beef was analyzed using 25 g test portions, and wet dog food was analyzed using 375 g test portions. For the reference methods, 25 g test portions of each matrix were analyzed. Each matrix was artificially contaminated with Salmonella at three inoculation levels: an uninoculated control level (0 CFU/test portion), a low inoculum level (0.2-2 CFU/test portion), and a high inoculum level (2-5 CFU/test portion). In this study, 1512 unpaired replicate samples were analyzed. Statistical analysis was conducted according to the probability of detection (POD). For the low-level raw ground beef test portions, the following dLPOD (difference between the LPODs of the reference and candidate method) values with 95% confidence intervals were obtained: -0.01 (-0.14, +0.12). For the low-level wet dog food test portions, the following dLPOD with 95% confidence intervals were obtained: -0.04 (-0.16, +0.09). No significant differences were observed in the number of positive samples detected by the 3M MDA Salmonella method versus either the USDA/FSIS-MLG or FDA/BAM methods.

Evaluation of 3M molecular detection assay (MDA) Salmonella for the detection of Salmonella in selected foods: collaborative study.

PubMed

Bird, Patrick; Fisher, Kiel; Boyle, Megan; Huffman, Travis; Benzinger, M Joseph; Bedinghaus, Paige; Flannery, Jonathan; Crowley, Erin; Agin, James; Goins, David; Benesh, DeAnn; David, John

2013-01-01

The 3M Molecular Detection Assay (MDA) Salmonella is used with the 3M Molecular Detection System for the detection of Salmonella spp. in food, food-related, and environmental samples after enrichment. The assay utilizes loop-mediated isothermal amplification to rapidly amplify Salmonella target DNA with high specificity and sensitivity, combined with bioluminescence to detect the amplification. The 3M MDA Salmonella method was compared using an unpaired study design in a multilaboratory collaborative study to the U.S. Department of Agriculture/Food Safety and Inspection Service-Microbiology Laboratory Guidebook (USDA/FSIS-MLG 4.05), Isolation and Identification of Salmonella from Meat, Poultry, Pasteurized Egg and Catfish Products for raw ground beef and the U.S. Food and Drug Administration/Bacteriological Analytical Manual (FDA/BAM) Chapter 5 Salmonella reference method for wet dog food following the current AOAC guidelines. A total of 20 laboratories participated. For the 3M MDA Salmonella method, raw ground beef was analyzed using 25 g test portions, and wet dog food was analyzed using 375 g test portions. For the reference methods, 25 g test portions of each matrix were analyzed. Each matrix was artificially contaminated with Salmonella at three inoculation levels: an uninoculated control level (0 CFU/test portion), a low inoculum level (0.2-2 CFU/test portion), and a high inoculum level (2-5 CFU/test portion). In this study, 1512 unpaired replicate samples were analyzed. Statistical analysis was conducted according to the probability of detection (POD). For the low-level raw ground beef test portions, the following dLPOD (difference between the POD of the reference and candidate method) values with 95% confidence intervals were obtained: -0.01 (-0.14, +0.12). For the low-level wet dog food test portions, the following dLPOD with 95% confidence intervals were obtained: -0.04 (-0.16, +0.09). No significant differences were observed in the number of positive samples detected by the 3M MDA Salmonella method versus either the USDA/FSIS-MLG or FDA/BAM methods.

Biodegradation of the nitramine explosive CL-20.

PubMed

Trott, Sandra; Nishino, Shirley F; Hawari, Jalal; Spain, Jim C

2003-03-01

The cyclic nitramine explosive CL-20 (2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane) was examined in soil microcosms to determine whether it is biodegradable. CL-20 was incubated with a variety of soils. The explosive disappeared in all microcosms except the controls in which microbial activity had been inhibited. CL-20 was degraded most rapidly in garden soil. After 2 days of incubation, about 80% of the initial CL-20 had disappeared. A CL-20-degrading bacterial strain, Agrobacterium sp. strain JS71, was isolated from enrichment cultures containing garden soil as an inoculum, succinate as a carbon source, and CL-20 as a nitrogen source. Growth experiments revealed that strain JS71 used 3 mol of nitrogen per mol of CL-20.

Biodegradation of the Nitramine Explosive CL-20

PubMed Central

Trott, Sandra; Nishino, Shirley F.; Hawari, Jalal; Spain, Jim C.

2003-01-01

The cyclic nitramine explosive CL-20 (2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane) was examined in soil microcosms to determine whether it is biodegradable. CL-20 was incubated with a variety of soils. The explosive disappeared in all microcosms except the controls in which microbial activity had been inhibited. CL-20 was degraded most rapidly in garden soil. After 2 days of incubation, about 80% of the initial CL-20 had disappeared. A CL-20-degrading bacterial strain, Agrobacterium sp. strain JS71, was isolated from enrichment cultures containing garden soil as an inoculum, succinate as a carbon source, and CL-20 as a nitrogen source. Growth experiments revealed that strain JS71 used 3 mol of nitrogen per mol of CL-20. PMID:12620886

["In vitro" interactions between influenza virus and mouse lung alveolar macrophages (author's transl)].

PubMed

Lemercier, G; Mavet, S; Burckhart, M F; Fontanges, R

1979-01-01

Interactions between influenza virus A/PR/8/34 (H0N1) and Balb/c mouse lung alveolar macrophages have been studied in vitro. One day after initiation of alveolar macrophage culture in 35 mm Falcon dishes, the virus suspension was allowed to adsorb to the cells for 1 h. Detachment of cells from the plastic substrate, morphological changes in adherent cells and decreased phagocytosis of heat-killed Candida albicans occured slowly as compared to control cultures. These facts appeared to be directly correlated to the concentration of viruses in the inoculum. Data yielded by virus titrations, electron microscopy and immunofluorescence suggest that mouse lung alveolar macrophages are able to take up a large amount of viral particles and inhibit their replication, allowing only an abortive viral cycle.

Characterization and optimization of schizophyllan production from date syrup.

PubMed

Jamshidian, Hajar; Shojaosadati, Seyed Abbas; Vilaplana, Francisco; Mousavi, Seyed Mohammad; Soudi, Mohammad Reza

2016-11-01

This study demonstrates the efficient utilization of low-cost agricultural substrates, particularly date syrup, by Schizophyllum commune ATCC 38548 for schizophyllan production. Initially, one factor-at-a-time method was used to find the best carbon and nitrogen sources for schizophyllan production. Subsequently, response surface methodology was employed to optimize the level of culture medium components to maximize substrate conversion yield and schizophyllan production in submerged culture. Maximum product yield (0.12g schizophyllan/g date syrup) and schizophyllan production (8.5g/l) were obtained at concentrations of date syrup and corn steep liquor, inoculum size and agitation rate at 7.02%w/v, 0.10%w/v, 7.68%v/v and 181rpm, respectively. Sugar composition analysis, FTIR, NMR and molar mass determination revealed the purity and molecular properties of recovered schizophyllan produced from date syrup as glycosidic linkage analysis showed three main schizophyllan characteristic peaks arising from the 3-linked, 3,6-linked and terminal glucose residues. Finally, process economic analysis suggested that use of date syrup and corn steep liquor as nutrients would result in approximately 6-fold reduction in cost of raw materials for schizophyllan production as compared to conventional carbon and nitrogen sources such as sucrose and malt extract. Copyright © 2016 Elsevier B.V. All rights reserved.

Analysis of Biomethanation Process from market waste to generate bio energy

NASA Astrophysics Data System (ADS)

Sathish, S.; Parthiban, A.; Vinod kumar, T.; Chandrasekaran, M.

2017-03-01

In this study was to incur that the biogas production from traditional market wastes which were represented by cabbage stem and carrot peeling, white mustard were under taken in a laboratory experiment. To produce biogas, the raw material such as cabbage stem and carrot peeling, white mustard and carrot peeling were mixed until C/N ratio close 30:1. Inoculums starter cow dung is put into digester then water is added until 500 liters. The initial pH is measured at throughout the experiments. The anaerobic digestion process is conducted at temperature of 30ºC and the volumes, pH of the biogas yield were observed daily. Biogas yield and cumulative biogas, total solids were analyzed 35 days. The cumulative biogas yield at the 32th day of digestion for cabbage stem and carrot peeling (exp1), white mustard and carrot peeling (exp2) were 2140 liters and 2421 liters respectively. The highest daily biogas yield is achieved on the 22st day of digestion which is found 123 liters and 141 liters respectively. In the first 10 days, the pH level is observed decrease and increase after the day of 21. Although at the end of digestion period the pH will fall down.

Fungi isolated from flue-cured tobacco inoculated in the field with storage fungi.

PubMed

Welty, R E

1971-03-01

Flue-cured tobacco inoculated in the field with A. amstelodami, A. flavus, A. ochraceus, A. repens, A. ruber, and a species of Penicillium was rarely invaded by these fungi. Regardless of inoculum, the predominant fungi reisolated from green tissue were species of Alternaria and Cladosporium. After curing, A. repens, A. niger, and species of Alternaria and a species of Penicillium were the most commonly isolated fungi. The fungus used as inoculum was not the predominant fungus reisolated from green or cured tissue. Conditions during handling and storage prior to marketing probably determine when storage fungi become associated with the leaf and which species becomes predominant.

Production of native arbuscular mycorrhizal fungi inoculum under different environmental conditions.

PubMed

Torres-Arias, Yamir; Fors, Rosalba Ortega; Nobre, Camila; Gómez, Eduardo Furrazola; Berbara, Ricardo Luis Louro

In order to obtain an arbuscular mycorrhizal fungi (AMF) native inoculum from Sierra de Moa and determine the most appropriate conditions for its big scale production, four light and temperature combinations were tested in three plant species (Calophyllum antillanum, Talipariti elatum and Paspalum notatum). Growth and development parameters, as well as the mycorrhizal functioning of the seedlings were evaluated. The natural light treatment under high temperatures (L-H) was the most suitable for the growth and development of the three plant species, showing the highest total biomass values, mainly of root, and a positive root-shoot ratio balance. This treatment also promoted higher values of root mycorrhizal colonization, external mycelium and AMF spore density. A total of 38 AMF species were identified among the plants and environmental conditions tested. Archaeospora sp.1, Glomus sp.5, Glomus brohultii and G. glomerulatum were observed in all the treatments. The L-H condition can be recommended for native inoculum production, as it promotes a better expression of the AM symbiosis and an elevated production of mycorrhizal propagules. Copyright © 2016 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

Two-Stage Fungal Pre-Treatment for Improved Biogas Production from Sisal Leaf Decortication Residues

PubMed Central

Muthangya, Mutemi; Mshandete, Anthony Manoni; Kivaisi, Amelia Kajumulo

2009-01-01

Sisal leaf decortications residue (SLDR) is amongst the most abundant agro-industrial residues in Tanzania and is a good feedstock for biogas production. Pre-treatment of the residue prior to its anaerobic digestion (AD) was investigated using a two-stage pre-treatment approach with two fungal strains, CCHT-1 and Trichoderma reesei in succession in anaerobic batch bioreactors. AD of the pre-treated residue with CCTH-1 at 10% (wet weight inoculum/SLDR) inoculum concentration incubated for four days followed by incubation for eight days with 25% (wet weight inoculum/SLDR) of T. reesei gave a methane yield of 0.292 ± 0.04 m3 CH4/kg volatile solids (VS)added. On reversing the pre-treatment succession of the fungal inocula using the same parameters followed by AD, methane yield decreased by about 55%. Generally, an increment in the range of 30–101% in methane yield in comparison to the un-treated SLDR was obtained. The results confirmed the potential of CCHT-1 followed by Trichoderma reesei fungi pre-treatment prior to AD to achieve significant improvement in biogas production from SLDR. PMID:20087466

Study of Methanogenesis while Bioutilisation of Plant Residuals

NASA Astrophysics Data System (ADS)

Ilyin, V. K.; Korniushenkova, I. N.; Starkova, L. V.; Lauriniavichius, K. S.

respect principals of planet ecology, and compatibility with other habitability systems. For these purpose the waste management technologies, relevant to application of the biodegradation properties of bacteria are of great value. Biological treatment method is based upon the biodegradation of organic substances by various microorganisms. vegetable non-edible residual, using artificial inoculum; to study peculiarities of biogas, possibilities to optimize or to reduce the share of methane. fermentation. The biogas production achieved 46 l per 1 kg of substrate. The microbial studies of biodegradation process revealed following peculiarities: (i)gradual quantitative increasing of Lactobacillus sp. (from 103 to 105 colony forming units (CFU) per ml); (ii)activation of Clostridia sp. (from 102 to 104 CFU/ml); (iii) elimination of aerobic conventional pathogens (Enterobacteriaceae sp., Protea sp., staphylococci). methane content measures revealed traces 0.1-0.4%. granules, the amount of methane in biogas reached 80-90%. biodegradation of vegetable wastes. This inoculum consists of active sludge adapted to wastes mixed with excretes of insects which consume plant wastes. Using this inoculum the biodegradation process takes less time, then that using active sludge. Regulation of methane concentration from traces to 90% may be achieved by adding of methane reactor to the plant digester.

Mechanism, Kinetics and Microbiology of Inhibition Caused by Long-Chain Fatty Acids in Anaerobic Digestion of Algal Biomass

DOE PAGES

Ma, Jingwei; Zhao, Quan-Bao; Laurens, Lieve L.; ...

2015-09-15

Oleaginous microalgae contain a high level of lipids, which can be extracted and converted to biofuel. The lipid-extracted residue can then be further utilized through anaerobic digestion to produce biogas. However, long-chain fatty acids (LCFAs) have been identified as the main inhibitory factor on microbial activity of anaerobic consortium. In this study, the mechanism of LCFA inhibition on anaerobic digestion of whole and lipid-extracted algal biomass was investigated with a range of calcium concentrations against various inoculum to substrate ratios as a means to alleviate the LCFA inhibition.

Mechanism, Kinetics and Microbiology of Inhibition Caused by Long-Chain Fatty Acids in Anaerobic Digestion of Algal Biomass

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ma, Jingwei; Zhao, Quan-Bao; Laurens, Lieve L.

Oleaginous microalgae contain a high level of lipids, which can be extracted and converted to biofuel. The lipid-extracted residue can then be further utilized through anaerobic digestion to produce biogas. However, long-chain fatty acids (LCFAs) have been identified as the main inhibitory factor on microbial activity of anaerobic consortium. In this study, the mechanism of LCFA inhibition on anaerobic digestion of whole and lipid-extracted algal biomass was investigated with a range of calcium concentrations against various inoculum to substrate ratios as a means to alleviate the LCFA inhibition.

Potential of Rice Stubble as a Reservoir of Bradyrhizobial Inoculum in Rice-Legume Crop Rotation

PubMed Central

Piromyou, Pongdet; Greetatorn, Teerana; Teamtisong, Kamonluck; Tittabutr, Panlada; Boonkerd, Nantakorn

2017-01-01

ABSTRACT Bradyrhizobium encompasses a variety of bacteria that can live in symbiotic and endophytic associations with leguminous and nonleguminous plants, such as rice. Therefore, it can be expected that rice endophytic bradyrhizobia can be applied in the rice-legume crop rotation system. Some endophytic bradyrhizobial strains were isolated from rice (Oryza sativa L.) tissues. The rice biomass could be enhanced when supplementing bradyrhizobial strain inoculation with KNO3, NH4NO3, or urea, especially in Bradyrhizobium sp. strain SUTN9-2. In contrast, the strains which suppressed rice growth were photosynthetic bradyrhizobia and were found to produce nitric oxide (NO) in the rice root. The expression of genes involved in NO production was conducted using a quantitative reverse transcription-PCR (qRT-PCR) technique. The nirK gene expression level in Bradyrhizobium sp. strain SUT-PR48 with nitrate was higher than that of the norB gene. In contrast, the inoculation of SUTN9-2 resulted in a lower expression of the nirK gene than that of the norB gene. These results suggest that SUT-PR48 may accumulate NO more than SUTN9-2 does. Furthermore, the nifH expression of SUTN9-2 was induced in treatment without nitrogen supplementation in an endophytic association with rice. The indole-3-acetic acid (IAA) and 1-amino-cyclopropane-1-carboxylic acid (ACC) deaminase produced in planta by SUTN9-2 were also detected. Enumeration of rice endophytic bradyrhizobia from rice tissues revealed that SUTN9-2 persisted in rice tissues until rice-harvesting season. The mung bean (Vigna radiata) can be nodulated after rice stubbles were decomposed. Therefore, it is possible that rice stubbles can be used as an inoculum in the rice-legume crop rotation system under both low- and high-organic-matter soil conditions. IMPORTANCE This study shows that some rice endophytic bradyrhizobia could produce IAA and ACC deaminase and have a nitrogen fixation ability during symbiosis inside rice tissues. These characteristics may play an important role in rice growth promotion by endophytic bradyrhizobia. However, the NO-producing strains should be of concern due to a possible deleterious effect of NO on rice growth. In addition, this study reports the application of endophytic bradyrhizobia in rice stubbles, and the rice stubbles were used directly as an inoculum for a leguminous plant (mung bean). The degradation of rice stubbles leads to an increased number of SUTN9-2 in the soil and may result in increased mung bean nodulation. Therefore, the persistence of endophytic bradyrhizobia in rice tissues can be developed to use rice stubbles as an inoculum for mung bean in a rice-legume crop rotation system. PMID:28916558

Potential of Rice Stubble as a Reservoir of Bradyrhizobial Inoculum in Rice-Legume Crop Rotation.

PubMed

Piromyou, Pongdet; Greetatorn, Teerana; Teamtisong, Kamonluck; Tittabutr, Panlada; Boonkerd, Nantakorn; Teaumroong, Neung

2017-11-15

Bradyrhizobium encompasses a variety of bacteria that can live in symbiotic and endophytic associations with leguminous and nonleguminous plants, such as rice. Therefore, it can be expected that rice endophytic bradyrhizobia can be applied in the rice-legume crop rotation system. Some endophytic bradyrhizobial strains were isolated from rice ( Oryza sativa L.) tissues. The rice biomass could be enhanced when supplementing bradyrhizobial strain inoculation with KNO 3 , NH 4 NO 3 , or urea, especially in Bradyrhizobium sp. strain SUTN9-2. In contrast, the strains which suppressed rice growth were photosynthetic bradyrhizobia and were found to produce nitric oxide (NO) in the rice root. The expression of genes involved in NO production was conducted using a quantitative reverse transcription-PCR (qRT-PCR) technique. The nirK gene expression level in Bradyrhizobium sp. strain SUT-PR48 with nitrate was higher than that of the norB gene. In contrast, the inoculation of SUTN9-2 resulted in a lower expression of the nirK gene than that of the norB gene. These results suggest that SUT-PR48 may accumulate NO more than SUTN9-2 does. Furthermore, the nifH expression of SUTN9-2 was induced in treatment without nitrogen supplementation in an endophytic association with rice. The indole-3-acetic acid (IAA) and 1-amino-cyclopropane-1-carboxylic acid (ACC) deaminase produced in planta by SUTN9-2 were also detected. Enumeration of rice endophytic bradyrhizobia from rice tissues revealed that SUTN9-2 persisted in rice tissues until rice-harvesting season. The mung bean ( Vigna radiata ) can be nodulated after rice stubbles were decomposed. Therefore, it is possible that rice stubbles can be used as an inoculum in the rice-legume crop rotation system under both low- and high-organic-matter soil conditions. IMPORTANCE This study shows that some rice endophytic bradyrhizobia could produce IAA and ACC deaminase and have a nitrogen fixation ability during symbiosis inside rice tissues. These characteristics may play an important role in rice growth promotion by endophytic bradyrhizobia. However, the NO-producing strains should be of concern due to a possible deleterious effect of NO on rice growth. In addition, this study reports the application of endophytic bradyrhizobia in rice stubbles, and the rice stubbles were used directly as an inoculum for a leguminous plant (mung bean). The degradation of rice stubbles leads to an increased number of SUTN9-2 in the soil and may result in increased mung bean nodulation. Therefore, the persistence of endophytic bradyrhizobia in rice tissues can be developed to use rice stubbles as an inoculum for mung bean in a rice-legume crop rotation system. Copyright © 2017 American Society for Microbiology.

Study of the cross-contamination and survival of Salmonella in fresh apples.

PubMed

Perez-Rodriguez, F; Begum, M; Johannessen, G S

2014-08-01

The present work aimed at studying the cross contamination of apples by Salmonella during the processing of commercial fresh apples and its survival capacity on apple at room temperature. For the first study, the typical process of fresh apples was simulated at laboratory scale in which an apple that was artificially contaminated by Salmonella at different concentration levels (8, 6 and 5 log cfu/apple) was introduced in one batch and processed including a simulated transport/washing step and drying step using sponges to simulate the porous material used in the industry. Results indicated that at 8 log cfu/apple, 50% fresh apples were contaminated after processing, with all analysed environmental samples being positive for the pathogen, consisting of washing water and sponges. However, at lower inoculum levels (5-6 log cfu/apple) no cross contamination was detected in apples, and only environmental samples showed contamination by Salmonella after processing including both water and sponges. Experiments on the survival of Salmonella on apple showed that the pathogen was capable to survive for 12 days, only showing a significant drop at the end of the experiment. Finally, two-class attribute sampling plans were assessed as tool to detect Salmonella in different contamination scenarios in fresh apple. This analysis indicated that with the highest inoculum level, a total of 16 apples would be needed to reach 95% of detecting Salmonella (i.e. lot rejection). In turn, when low levels were assessed (5-6 log cfu/apple), a large number of apples (n=1021) would have to be sampled to obtain the same confidence level (95%). If the environment is sampled (i.e. water and sponges), a lower number of samples would be needed to detect the pathogen. However, the feasibility of environmental sampling has not been assessed from a practical point of view. Overall, the results in this study evidenced that cross contamination by Salmonella might occur during processing of fresh apples and subsequently, the pathogen might survive for a noticeable period of time. Copyright © 2014 Elsevier B.V. All rights reserved.

An in vitro evaluation of the effects of a Yucca schidigera extract and chestnut tannins on composition and metabolic profiles of canine and feline faecal microbiota.

PubMed

Pinna, Carlo; Vecchiato, Carla Giuditta; Cardenia, Vladimiro; Rodriguez-Estrada, Maria Teresa; Stefanelli, Claudio; Grandi, Monica; Gatta, Pier Paolo; Biagi, Giacomo

2017-10-01

The in vitro effect of a Yucca schidigera extract (YSE) and tannins from chestnut wood on composition and metabolic activity of canine and feline faecal microbiota was evaluated. Four treatments were carried out: control diet, chestnut tannins (CT), YSE and CT + YSE. The YSE was added to canine and feline faecal cultures at 0.1 g/l, while CT were added at 0.3 g/l for a 24-h incubation. A total of 130 volatile compounds were detected by means of headspace-solid phase microextraction gas-chromatography/mass spectrometry analyses. Several changes in the metabolite profiles of fermentation fluids were found, including a decrease of alcohols (-19%) and esters (-42%) in feline and canine inoculum, respectively, which was due to the antibacterial properties of tannins. In canine inoculum, after 6 h, YSE + CT caused lower cadaverine concentrations (-37%), while ammonia (-4%) and quinolone (-27%) were reduced by addition of CT. After 24 h, the presence of CT resulted in a decrease of sulphur compounds, such as dimethyl sulphide (-69%) and dimethyl disulphide (-20%). In feline faecal cultures, after 6 h, CT lowered the amount of indole (-48%), whereas YSE tended to decrease trimethylamine levels (-16%). Both in canine and feline inoculum, addition of CT and, to a minor extent, YSE affected volatile fatty acids patterns. In canine faecal cultures, CT exerted a marginal inhibitory effect on Escherichia coli population (-0.45 log 10 numbers of DNA copies/ml), while enterococci were increased (+2.06 log 10 numbers of DNA copies/ml) by YSE. The results from the present study show that YSE and tannins from chestnut wood exert different effects on the composition and metabolism of canine and feline faecal microbiota. In particular, the supplementation of YSE and tannins to diets for dogs and cats may be beneficial due to the reduction of the presence of some potentially toxic volatile metabolites in the animals' intestine.