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Sample records for aerobic growth conditions

  1. Influence of bovine lactoferrin on the growth of selected probiotic bacteria under aerobic conditions.

    PubMed

    Chen, Po-Wen; Ku, Yu-We; Chu, Fang-Yi

    2014-10-01

    Bovine lactoferrin (bLf) is a natural glycoprotein, and it shows broad-spectrum antimicrobial activity. However, reports on the influences of bLf on probiotic bacteria have been mixed. We examined the effects of apo-bLf (between 0.25 and 128 mg/mL) on both aerobic and anaerobic cultures of probiotics. We found that bLf had similar effects on the growth of probiotics under aerobic or anaerobic conditions, and that it actively and significantly (at concentrations of >0.25 mg/mL) retarded the growth rate of Bifidobacterium bifidum (ATCC 29521), B. longum (ATCC 15707), B. lactis (BCRC 17394), B. infantis (ATCC 15697), Lactobacillus reuteri (ATCC 23272), L. rhamnosus (ATCC 53103), and L. coryniformis (ATCC 25602) in a dose-dependent manner. Otherwise, minimal inhibitory concentrations (MICs) were 128 or >128 mg/mL against B. bifidum, B. longum, B. lactis, L. reuteri, and L. rhamnosus (ATCC 53103). With regard to MICs, bLf showed at least four-fold lower inhibitory effect on probiotics than on pathogens. Intriguingly, bLf (>0.25 mg/mL) significantly enhanced the growth of Rhamnosus (ATCC 7469) and L. acidophilus (BCRC 14065) by approximately 40-200 %, during their late periods of growth. Supernatants produced from aerobic but not anaerobic cultures of L. acidophilus reduced the growth of Escherichia coli by about 20 %. Thus, bLf displayed a dose-dependent inhibitory effect on the growth of most probiotic strains under either aerobic or anaerobic conditions. An antibacterial supernatant prepared from the aerobic cultures may have significant practical use. PMID:24916115

  2. Aerobic Conditioning Class.

    ERIC Educational Resources Information Center

    Johnson, Neil R.

    1980-01-01

    An aerobic exercise class that focuses on the conditioning of the cardiovascular and muscular systems is presented. Students complete data cards on heart rate, pulse, and exercises to be completed during the forty minute course. (CJ)

  3. Physiological activities associated with biofilm growth in attached and suspended growth bioreactors under aerobic and anaerobic conditions.

    PubMed

    Naz, Iffat; Seher, Shama; Perveen, Irum; Saroj, Devendra P; Ahmed, Safia

    2015-01-01

    This research work evaluated the biofilm succession on stone media and compared the biochemical changes of sludge in attached and suspended biological reactors operated under aerobic and anaerobic conditions. Stones incubated (30±2°C) with activated sludge showed a constant increase in biofilm weight up to the fifth and seventh week time under anaerobic and aerobic conditions, respectively, where after reduction (>80%) the most probable number index of pathogen indicators on ninth week was recorded. Reduction in parameters such as biological oxygen demand (BOD) (47.7%), chemical oxygen demand (COD, 41%), nitrites (60.2%), nitrates (105.5%) and phosphates (58.9%) and increase in dissolved oxygen (176.5%) of sludge were higher in aerobic attached growth reactors as compared with other settings. While, considerable reductions in these values were also observed (BOD, 53.8%; COD, 2.8%; nitrites, 28.6%; nitrates, 31.7%; phosphates, 41.4%) in the suspended growth system under anaerobic conditions. However, higher sulphate removal was observed in suspended (40.9% and 54.9%) as compared with biofilm reactors (28.2% and 29.3%). Six weeks biofilm on the stone media showed maximum physiological activities; thus, the operational conditions should be controlled to keep the biofilm structure similar to six-week-old biofilm, and can be used in fixed biofilm reactors for wastewater treatment. PMID:25609155

  4. The preferential growth of branched GDGT source microorganisms under aerobic conditions in peat revealed by stable isotope probing experiments

    NASA Astrophysics Data System (ADS)

    Huguet, Arnaud; Meador, Travis B.; Laggoun-Défarge, Fatima; Könneke, Martin; Derenne, Sylvie; Hinrichs, Kai-Uwe

    2016-04-01

    Branched glycerol dialkyl glycerol tetraether (brGDGTs) membrane lipids are widely distributed in aquatic and terrestrial environments and are being increasingly used as temperature proxies. Nevertheless, little is known regarding the microorganisms that produce these lipids, which are found in especially high abundance in the anaerobic horizons of peat bogs. We initiated stable isotope probing incubations of peat samples from a Sphagnum-dominated peatland (Jura Mountains, France) to measure the incorporation of (D)-D2O and 13C-labeled dissolved inorganic carbon (DIC) into brGDGTs, and thus gauge the activity, growth, and turnover times of their source organisms. Peat samples were collected from two adjacent sites with contrasting humidity levels (hereafter called "fen" and "bog" sites). For each site, samples from the surficial aerobic layer (acrotelm) and deeper anaerobic layer (catotelm) were collected and were incubated under both anaerobic and aerobic conditions for the acrotelm samples and only anaerobic conditions for the catotelm. The incubations were performed at 12 ° C, consistent with the mean summer air temperature at the sampling site. After two months of incubation, there was no incorporation of 13C label in brGDGTs for samples incubated under either aerobic or anaerobic conditions, showing that brGDGT-producing bacteria are heterotrophic microorganisms, as previously observed in organo-mineral soils (Weijers et al., 2011). Similarly, little to no deuterium incorporation was observed for brGDGTs isolated from anaerobically-incubated deep samples. In contrast, in the aerobic incubations of acrotelm samples from bog and fen, the weighted average δD of brGDGT core lipids (CLs) increased by up to 3332‰ and 933‰ after two months, respectively, indicating that fresh brGDGT CLs were biosynthesized at the peat surface. D incorporation into brGDGT CLs converted to production rates ranging from 30-106 ng cm‑3y‑1 in the aerobic acrotelm from bog and

  5. Development of a predictive model for the growth kinetics of aerobic microbial population on pomegranate marinated chicken breast fillets under isothermal and dynamic temperature conditions.

    PubMed

    Lytou, Anastasia; Panagou, Efstathios Z; Nychas, George-John E

    2016-05-01

    The aim of this study was the development of a model to describe the growth kinetics of aerobic microbial population of chicken breast fillets marinated in pomegranate juice under isothermal and dynamic temperature conditions. Moreover, the effect of pomegranate juice on the extension of the shelf life of the product was investigated. Samples (10 g) of chicken breast fillets were immersed in marinades containing pomegranate juice for 3 h at 4 °C following storage under aerobic conditions at 4, 10, and 15 °C for 10 days. Total Viable Counts (TVC), Pseudomonas spp and lactic acid bacteria (LAB) were enumerated, in parallel with sensory assessment (odor and overall appearance) of marinated and non-marinated samples. The Baranyi model was fitted to the growth data of TVC to calculate the maximum specific growth rate (μmax) that was further modeled as a function of temperature using a square root-type model. The validation of the model was conducted under dynamic temperature conditions based on two fluctuating temperature scenarios with periodic changes from 6 to 13 °C. The shelf life was determined both mathematically and with sensory assessment and its temperature dependence was modeled by an Arrhenius type equation. Results showed that the μmax of TVC of marinated samples was significantly lower compared to control samples regardless temperature, while under dynamic temperature conditions the model satisfactorily predicted the growth of TVC in both control and marinated samples. The shelf-life of marinated samples was significantly extended compared to the control (5 days extension at 4 °C). The calculated activation energies (Ea), 82 and 52 kJ/mol for control and marinated samples, respectively, indicated higher temperature dependence of the shelf life of control samples compared to marinated ones. The present results indicated that pomegranate juice could be used as an alternative ingredient in marinades to prolong the shelf life of chicken. PMID:26742613

  6. Media for the aerobic growth of campylobacter

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effect of agar and sodium bicarbonate (NaHCO3) concentration on aerobic growth of Campylobacter in a fumarate-pyruvate medium was examined. The broth medium was supplemented with 0.0 to 0.2% agar and inoculated with 106 CFU/ml of Campylobacter coli 33559, Campylobacter fetus 27349, Campylobacter...

  7. Aerobic and anaerobic growth of Paracoccus denitrificans on methanol.

    PubMed

    Bamforth, C W; Quayle, J R

    1978-10-01

    1. The dye-linked methanol dehydrogenase from Paracoccus denitrificans grown aerobically on methanol has been purified and its properties compared with similar enzymes from other bacteria. It was shown to be specific and to have high affinity for primary alcohols and formaldehyde as substrate, ammonia was the best activator and the enzyme could be linked to reduction of phenazine methosulphate. 2. Paracoccus denitrificans could be grown anaerobically on methanol, using nitrate or nitrite as electron acceptor. The methanol dehydrogenase synthesized under these conditions could not be differentiated from the aerobically-synthesized enzyme. 3. Activities of methanol dehydrogenase, formaldehyde dehydrogenase, formate dehydrogenase, nitrate reductase and nitrite reductase were measured under aerobic and anaerobic growth conditions. 4. Difference spectra of reduced and oxidized cytochromes in membrane and supernatant fractions of methanol-grown P. denitrificans were measured. 5. From the results of the spectral and enzymatic analyses it has been suggested that anaerobic growth on methanol/nitrate is made possible by reduction of nitrate to nitrite using electrons derived from the pyridine nucleotide-linked dehydrogenations of formaldehyde and formate, the nitrite so produced then functioning as electron acceptor for methanol dehydrogenase via cytochrome c and nitrite reductase. PMID:718372

  8. C4-Dicarboxylate Utilization in Aerobic and Anaerobic Growth.

    PubMed

    Unden, Gottfried; Strecker, Alexander; Kleefeld, Alexandra; Kim, Ok Bin

    2016-06-01

    C4-dicarboxylates and the C4-dicarboxylic amino acid l-aspartate support aerobic and anaerobic growth of Escherichia coli and related bacteria. In aerobic growth, succinate, fumarate, D- and L-malate, L-aspartate, and L-tartrate are metabolized by the citric acid cycle and associated reactions. Because of the interruption of the citric acid cycle under anaerobic conditions, anaerobic metabolism of C4-dicarboxylates depends on fumarate reduction to succinate (fumarate respiration). In some related bacteria (e.g., Klebsiella), utilization of C4-dicarboxylates, such as tartrate, is independent of fumarate respiration and uses a Na+-dependent membrane-bound oxaloacetate decarboxylase. Uptake of the C4-dicarboxylates into the bacteria (and anaerobic export of succinate) is achieved under aerobic and anaerobic conditions by different sets of secondary transporters. Expression of the genes for C4-dicarboxylate metabolism is induced in the presence of external C4-dicarboxylates by the membrane-bound DcuS-DcuR two-component system. Noncommon C4-dicarboxylates like l-tartrate or D-malate are perceived by cytoplasmic one-component sensors/transcriptional regulators. This article describes the pathways of aerobic and anaerobic C4-dicarboxylate metabolism and their regulation. The citric acid cycle, fumarate respiration, and fumarate reductase are covered in other articles and discussed here only in the context of C4-dicarboxylate metabolism. Recent aspects of C4-dicarboxylate metabolism like transport, sensing, and regulation will be treated in more detail. This article is an updated version of an article published in 2004 in EcoSal Plus. The update includes new literature, but, in particular, the sections on the metabolism of noncommon C4-dicarboxylates and their regulation, on the DcuS-DcuR regulatory system, and on succinate production by engineered E. coli are largely revised or new. PMID:27415771

  9. Conditioning and Aerobics for Older Americans.

    ERIC Educational Resources Information Center

    Hansen, Joyce

    1980-01-01

    A class designed for the maintenance and gradual improvement of senior citizens' physical fitness includes relaxation training, flexibility and stretching exercises, interval training activities (designed as a link between less strenuous exercise and more strenuous activities), and aerobic exercises. (CJ)

  10. Assessment of Aerobic and Respiratory Growth in the Lactobacillus casei Group

    PubMed Central

    Zotta, Teresa; Ricciardi, Annamaria; Ianniello, Rocco G.; Parente, Eugenio; Reale, Anna; Rossi, Franca; Iacumin, Lucilla; Comi, Giuseppe; Coppola, Raffaele

    2014-01-01

    One hundred eighty four strains belonging to the species Lactobacillus casei, L. paracasei and L. rhamnosus were screened for their ability to grow under aerobic conditions, in media containing heme and menaquinone and/or compounds generating reactive oxygen species (ROS), in order to identify respiratory and oxygen-tolerant phenotypes. Most strains were able to cope with aerobic conditions and for many strains aerobic growth and heme or heme/menaquinone supplementation increased biomass production compared to anaerobic cultivation. Only four L. casei strains showed a catalase-like activity under anaerobic, aerobic and respiratory conditions and were able to survive in presence of H2O2 (1 mM). Almost all L. casei and L. paracasei strains tolerated menadione (0.2 mM) and most tolerated pyrogallol (50 mM), while L. rhamnosus was usually resistant only to the latter compound. This is the first study in which an extensive screening of oxygen and oxidative stress tolerance of members of the L. casei group has been carried out. Results allowed the selection of strains showing the typical traits of aerobic and respiratory metabolism (increased pH and biomass under aerobic or respiratory conditions) and unique oxidative stress response properties. Aerobic growth and respiration may confer technological and physiological advantages in the L. casei group and oxygen-tolerant phenotypes could be exploited in several food industry applications. PMID:24918811

  11. Growth of Campylobacter Incubated Aerobically in Media Supplemented with Peptones

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Growth of Campylobacter cultures incubated aerobically in media supplemented with peptones was studied, and additional experiments were conducted to compare growth of the bacteria in media supplemented with peptones to growth in media supplemented with fumarate-pyruvate-minerals-vitamins (FPMV). A b...

  12. Chemotactic Motility of Pseudomonas fluorescens F113 under Aerobic and Denitrification Conditions

    PubMed Central

    Redondo-Nieto, Miguel; Rivilla, Rafael; Martín, Marta

    2015-01-01

    The sequence of the genome of Pseudomonas fluorescens F113 has shown the presence of multiple traits relevant for rhizosphere colonization and plant growth promotion. Among these traits are denitrification and chemotactic motility. Besides aerobic growth, F113 is able to grow anaerobically using nitrate and nitrite as final electron acceptors. F113 is able to perform swimming motility under aerobic conditions and under anaerobic conditions when nitrate is used as the electron acceptor. However, nitrite can not support swimming motility. Regulation of swimming motility is similar under aerobic and anaerobic conditions, since mutants that are hypermotile under aerobic conditions, such as gacS, sadB, kinB, algU and wspR, are also hypermotile under anaerobic conditions. However, chemotactic behavior is different under aerobic and denitrification conditions. Unlike most pseudomonads, the F113 genome encode three complete chemotaxis systems, Che1, Che2 and Che3. Mutations in each of the cheA genes of the three Che systems has shown that the three systems are functional and independent. Mutation of the cheA1 gene completely abolished swimming motility both under aerobic and denitrification conditions. Mutation of the cheA2 gene, showed only a decrease in swimming motility under both conditions, indicating that this system is not essential for chemotactic motility but is necessary for optimal motility. Mutation of the cheA3 gene abolished motility under denitrification conditions but only produced a decrease in motility under aerobic conditions. The three Che systems proved to be implicated in competitive rhizosphere colonization, being the cheA1 mutant the most affected. PMID:26161531

  13. Development of microorganisms in the chernozem under aerobic and anaerobic conditions

    NASA Astrophysics Data System (ADS)

    Polyanskaya, L. M.; Gorbacheva, M. A.; Milanovskii, E. Yu.; Zvyagintsev, D. G.

    2010-03-01

    A microbial succession was studied under aerobic and anaerobic conditions by means of experiments with microcosms in different horizons of a chernozem. It was revealed that, under aerobic conditions, all the microorganisms grow irrespective of the soil horizon; fungi and bacteria grow at the first succession stages, and actinomycetes grow at the last stages. It was shown that, in the case of a simulated anaerobiosis commonly used to study anaerobic populations of bacteria, the mycelium of micromycetes grows in the upper part of the chernozem’s A horizon. Under anaerobic conditions, the peak of the mycelium development is shifted from the 3rd to 7th days (typical for aerobic conditions) to the 7th to 15th days of incubation. The level of mycelium length’s stabilization under aerobic and anaerobic conditions also differs: it is higher or lower than the initial one, respectively. Under anaerobic conditions, the growth of fungal mycelium, bacteria, and actinomycetes in the lower part of the A horizon and in the B horizon is extremely weak. There was not any observed growth of actinomycetes in all the chernozem’s horizons under anaerobic conditions.

  14. Decomposition of organic waste products under aerobic and anaerobic conditions

    SciTech Connect

    Gale, P.M.

    1988-01-01

    The objectives of this research were to determine the kinetics of C and N mineralization under aerobic and anaerobic conditions. These parameters were then used to verify the simulation model, DECOMPOSITION, for the anaerobic system. Incubation experiments were conducted to compare the aerobic and anaerobic decomposition of alfalfa (Medicago sativa L.), a substrate with a low C:N ratio. Under anaerobic conditions the net mineralization of N occurred more rapidly than that under aerobic conditions. However, the rate of C mineralization as measured by CO{sub 2} evolution was much lower. For the anaerobic decomposition of alfalfa, C mineralization was best described as the sum of the CO{sub 2} and CH{sub 4} evolved plus the water soluble organic C formed. The kinetics of C mineralization, as determined by this approach, were used to successfully predict the rate and amount of N mineralization from alfalfa undergoing anaerobic decomposition. The decomposition of paper mill sludge, a high C:N ratio substrate, was also evaluated.

  15. Detoxification of furfural in Corynebacterium glutamicum under aerobic and anaerobic conditions.

    PubMed

    Tsuge, Yota; Hori, Yoshimi; Kudou, Motonori; Ishii, Jun; Hasunuma, Tomohisa; Kondo, Akihiko

    2014-10-01

    The toxic fermentation inhibitors in lignocellulosic hydrolysates raise serious problems for the microbial production of fuels and chemicals. Furfural is considered to be one of the most toxic compounds among these inhibitors. Here, we describe the detoxification of furfural in Corynebacterium glutamicum ATCC13032 under both aerobic and anaerobic conditions. Under aerobic culture conditions, furfuryl alcohol and 2-furoic acid were produced as detoxification products of furfural. The ratio of the products varied depending on the initial furfural concentration. Neither furfuryl alcohol nor 2-furoic acid showed any toxic effect on cell growth, and both compounds were determined to be the end products of furfural degradation. Interestingly, unlike under aerobic conditions, most of the furfural was converted to furfuryl alcohol under anaerobic conditions, without affecting the glucose consumption rate. Both the NADH/NAD(+) and NADPH/NADP(+) ratio decreased in the accordance with furfural concentration under both aerobic and anaerobic conditions. These results indicate the presence of a single or multiple endogenous enzymes with broad and high affinity for furfural and co-factors in C. glutamicum ATCC13032. PMID:25112225

  16. Binary Interactions of Antagonistic Bacteria with Candida albicans Under Aerobic and Anaerobic Conditions.

    PubMed

    Benadé, Eliska; Stone, Wendy; Mouton, Marnel; Postma, Ferdinand; Wilsenach, Jac; Botha, Alfred

    2016-04-01

    We used both aerobic and anaerobic liquid co-cultures, prepared with Luria Bertani broth, to study the effect of bacteria on the survival of Candida albicans in the external environment, away from an animal host. The bacteria were represented by Aeromonas hydrophila, Bacillus cereus, Bacillus subtilis, Clostridium, Enterobacter, Klebsiella pneumoniae, Kluyvera ascorbata and Serratia marcescens. Under aerobic conditions, the yeast's growth was inhibited in the presence of bacterial growth; however, under anaerobic conditions, yeast and bacterial growth in co-cultures was similar to that observed for pure cultures. Subsequent assays revealed that the majority of bacterial strains aerobically produced extracellular hydrolytic enzymes capable of yeast cell wall hydrolysis, including chitinases and mannan-degrading enzymes. In contrast, except for the A. hydrophila strain, these enzymes were not detected in anaerobic bacterial cultures, nor was the antimicrobial compound prodigiosin found in anaerobic cultures of S. marcescens. When we suspended C. albicans cells in crude extracellular enzyme preparations from K. pneumoniae and S. marcescens, we detected no negative effect on yeast viability. However, we found that these preparations enhance the toxicity of prodigiosin towards the yeast, especially in combination with mannan-degrading enzymes. Analyses of the chitin and mannan content of yeast cell walls revealed that less chitin was produced under anaerobic than aerobic conditions; however, the levels of mannan, known for its low permeability, remained the same. The latter phenomenon, as well as reduced production of the bacterial enzymes and prodigiosin, may contribute to anaerobic growth and survival of C. albicans in the presence of bacteria. PMID:26566932

  17. Nitroglycerin degradation mediated by soil organic carbon under aerobic conditions.

    PubMed

    Bordeleau, Geneviève; Martel, Richard; Bamba, Abraham N'Valoua; Blais, Jean-François; Ampleman, Guy; Thiboutot, Sonia

    2014-10-01

    The presence of nitroglycerin (NG) has been reported in shallow soils and pore water of several military training ranges. In this context, NG concentrations can be reduced through various natural attenuation processes, but these have not been thoroughly documented. This study aimed at investigating the role of soil organic matter (SOM) in the natural attenuation of NG, under aerobic conditions typical of shallow soils. The role of SOM in NG degradation has already been documented under anoxic conditions, and was attributed to SOM-mediated electron transfer involving different reducing agents. However, unsaturated soils are usually well-oxygenated, and it was not clear whether SOM could participate in NG degradation under these conditions. Our results from batch- and column-type experiments clearly demonstrate that in presence of dissolved organic matter (DOM) leached from a natural soil, partial NG degradation can be achieved. In presence of particulate organic matter (POM) from the same soil, complete NG degradation was achieved. Furthermore, POM caused rapid sorption of NG, which should result in NG retention in the organic matter-rich shallow horizons of the soil profile, thus promoting degradation. Based on degradation products, the reaction pathway appears to be reductive, in spite of the aerobic conditions. The relatively rapid reaction rates suggest that this process could significantly participate in the natural attenuation of NG, both on military training ranges and in contaminated soil at production facilities. PMID:25086776

  18. Parallel pathways of ethoxylated alcohol biodegradation under aerobic conditions.

    PubMed

    Zembrzuska, Joanna; Budnik, Irena; Lukaszewski, Zenon

    2016-07-01

    Non-ionic surfactants (NS) are a major component of the surfactant flux discharged into surface water, and alcohol ethoxylates (AE) are the major component of this flux. Therefore, biodegradation pathways of AE deserve more thorough investigation. The aim of this work was to investigate the stages of biodegradation of homogeneous oxyethylated dodecanol C12E9 having 9 oxyethylene subunits, under aerobic conditions. Enterobacter strain Z3 bacteria were chosen as biodegrading organisms under conditions with C12E9 as the sole source of organic carbon. Bacterial consortia of river water were used in a parallel test as an inoculum for comparison. The LC-MS technique was used to identify the products of biodegradation. Liquid-liquid extraction with ethyl acetate was selected for the isolation of C12E9 and metabolites from the biodegradation broth. The LC-MS/MS technique operating in the multiple reaction monitoring (MRM) mode was used for quantitative determination of C12E9, C12E8, C12E7 and C12E6. Apart from the substrate, the homologues C12E8, C12E7 and C12E6, being metabolites of C12E9 biodegradation by shortening of the oxyethylene chain, as well as intermediate metabolites having a carboxyl end group in the oxyethylene chain (C12E8COOH, C12E7COOH, C12E6COOH and C12E5COOH), were identified. Poly(ethylene glycols) (E) having 9, 8 and 7 oxyethylene subunits were also identified, indicating parallel central fission of C12E9 and its metabolites. Similar results were obtained with river water as inoculum. It is concluded that AE, under aerobic conditions, are biodegraded via two parallel pathways: by central fission with the formation of PEG, and by Ω-oxidation of the oxyethylene chain with the formation of carboxylated AE and subsequent shortening of the oxyethylene chain by a single unit. PMID:27037882

  19. Ethanol production with Saccharomyces cerevisiae under aerobic conditions at different potassium concentrations

    SciTech Connect

    Wuempelmann, M.; Kjaergaard, L.; Joergensen, B.B.

    1984-01-01

    The specific ethanol productivity with Saccharomyces cerevisiae grown aerobicly in a chemostat was found to be highly dependent on the ratio of intracellular to extracellular potassium concentration through variations in the energy consumption used for maintenance of the concentration gradient of potassium across the cell membrane. The specific ethanol productivity progressively rose from 0 to 20 mmol h/sup -1/g/sup -1/ cell dry matter at a growth rate of 0.17 h/sup -1/ when the ratio of intracellular to extracellular potassium concentration was increased from 10 to 80. The ethanol production under potassium limited growth conditions was caused neither by a reduction in the specific respiratory activity nor by variations in the potassium content in cell dry matter. Results which strongly suggest that ethanol production under potassium limited growth conditions is brought about by changes in the ratio of pyruvate oxidase to pyruvate decarboxylase activity through changes in the intracellular pyruvate concentration are presented.

  20. Kinetics and thermodynamics of biodegradation of hydrolyzed polyacrylamide under anaerobic and aerobic conditions.

    PubMed

    Zhao, Lanmei; Bao, Mutai; Yan, Miao; Lu, Jinren

    2016-09-01

    Kinetics and thermodynamics of hydrolyzed polyacrylamide (HPAM) biodegradation in anaerobic and aerobic activated sludge biochemical treatment systems were explored to determine the maximum rate and feasibility of HPAM biodegradation. The optimal nutrient proportions for HPAM biodegradation were determined to be 0.08g·L(-1) C6H12O6, 1.00g·L(-1) NH4Cl, 0.36g·L(-1) NaH2PO4 and 3.00g·L(-1) K2HPO4 using response surface methodology (RSM). Based on the kinetics, the maximum HPAM biodegradation rates were 16.43385mg·L(-1)·d(-1) and 2.463mg·L(-1)·d(-1) in aerobic and anaerobic conditions, respectively. The activation energy (Ea) of the aerobic biodegradation was 48.9897kJ·mol(-1). Entropy changes (ΔS) of biochemical treatment system decreased from 216.21J·K(-1) to 2.39J·K(-1). Thermodynamic windows of opportunity for HPAM biodegradation were drawn. And it demonstrated HPAM was biodegraded into acetic acid and CO2 under laboratory conditions. Growth-process equations for functional bacteria anaerobically grown on polyacrylic acid were constructed and it confirmed electron equivalence between substrate and product. PMID:27235971

  1. Antimicrobial Susceptibility of Enteric Gram Negative Facultative Anaerobe Bacilli in Aerobic versus Anaerobic Conditions

    PubMed Central

    Amachawadi, Raghavendra G.; Renter, David G.; Volkova, Victoriya V.

    2016-01-01

    Antimicrobial treatments result in the host’s enteric bacteria being exposed to the antimicrobials. Pharmacodynamic models can describe how this exposure affects the enteric bacteria and their antimicrobial resistance. The models utilize measurements of bacterial antimicrobial susceptibility traditionally obtained in vitro in aerobic conditions. However, in vivo enteric bacteria are exposed to antimicrobials in anaerobic conditions of the lower intestine. Some of enteric bacteria of food animals are potential foodborne pathogens, e.g., Gram-negative bacilli Escherichia coli and Salmonella enterica. These are facultative anaerobes; their physiology and growth rates change in anaerobic conditions. We hypothesized that their antimicrobial susceptibility also changes, and evaluated differences in the susceptibility in aerobic vs. anaerobic conditions of generic E. coli and Salmonella enterica of diverse serovars isolated from cattle feces. Susceptibility of an isolate was evaluated as its minimum inhibitory concentration (MIC) measured by E-Test® following 24 hours of adaptation to the conditions on Mueller-Hinton agar, and on a more complex tryptic soy agar with 5% sheep blood (BAP) media. We considered all major antimicrobial drug classes used in the U.S. to treat cattle: β-lactams (specifically, ampicillin and ceftriaxone E-Test®), aminoglycosides (gentamicin and kanamycin), fluoroquinolones (enrofloxacin), classical macrolides (erythromycin), azalides (azithromycin), sulfanomides (sulfamethoxazole/trimethoprim), and tetracyclines (tetracycline). Statistical analyses were conducted for the isolates (n≥30) interpreted as susceptible to the antimicrobials based on the clinical breakpoint interpretation for human infection. Bacterial susceptibility to every antimicrobial tested was statistically significantly different in anaerobic vs. aerobic conditions on both media, except for no difference in susceptibility to ceftriaxone on BAP agar. A satellite experiment

  2. Aerobic carboxydotrophy under extremely haloalkaline conditions in Alkalispirillum/Alkalilimnicola strains isolated from soda lakes.

    PubMed

    Sorokin, Dimitry Yu; Tourova, Tatjana P; Kovaleva, Olga L; Kuenen, J Gijs; Muyzer, Gerard

    2010-03-01

    Aerobic enrichments from soda lake sediments with CO as the only substrate resulted in the isolation of five bacterial strains capable of autotrophic growth with CO at extremely high pH and salinity. The strains belonged to the Alkalispirillum/Alkalilimnicola cluster in the Gammaproteobacteria, where the ability to oxidize CO, but not growth with CO, has been demonstrated previously. The growth with CO was possible only at an oxygen concentration below 5 % and CO concentration below 20 % in the gas phase. The isolates were also capable of growth with formate but not with H(2). The carboxydotrophic growth occurred within a narrow pH range from 8 to 10.5 (optimum at 9.5) and a broad salt concentration from 0.3 to 3.5 M total Na(+) (optimum at 1.0 M). Cells grown on CO had high respiration activity with CO and formate, while the cells grown on formate actively oxidized formate alone. In CO-grown cells, CO-dehydrogenase (CODH) activity was detectable both in soluble and membrane fractions, while the NAD-independent formate dehydrogenase (FDH) resided solely in membranes. The results of total protein profiling and the failure to detect CODH with conventional primers for the coxL gene indicated that the CO-oxidizing enzyme in haloalkaliphilic isolates might differ from the classical aerobic CODH complex. A single cbbL gene encoding the RuBisCO large subunit was detected in all strains, suggesting the presence of the Calvin cycle of inorganic carbon fixation. Overall, these results demonstrated the possibility of aerobic carboxydotrophy under extremely haloalkaline conditions. PMID:19959573

  3. Summary report on the aerobic degradation of diesel fuel and the degradation of toluene under aerobic, denitrifying and sulfate reducing conditions

    SciTech Connect

    Coyne, P.; Smith, G.

    1995-08-15

    This report contains a number of studies that were performed to better understand the technology of the biodegradation of petroleum hydrocarbons. Topics of investigation include the following: diesel fuel degradation by Rhodococcus erythropolis; BTEX degradation by soil isolates; aerobic degradation of diesel fuel-respirometry; aerobic degradation of diesel fuel-shake culture; aerobic toluene degradation by A3; effect of HEPES, B1, and myo-inositol addition on the growth of A3; aerobic and anaerobic toluene degradation by contaminated soils; denitrifying bacteria MPNs; sulfate-reducing bacteria MPNs; and aerobic, DNB and SRB enrichments.

  4. Impact of ArcA loss in Shewanella oneidensis revealed by comparative proteomics under aerobic and anaerobic conditions

    SciTech Connect

    Yuan, Jie; Wei, Buyun; Lipton, Mary S.; Gao, Haichun

    2012-06-01

    Shewanella inhabit a wide variety of niches in nature and can utilize a broad spectrum of electron acceptors under anaerobic conditions. How they modulate their gene expression to adapt is poorly understood. ArcA, homologue of a global regulator controlling hundreds of genes involved in aerobic and anaerobic respiration in E. coli, was shown to be important in aerobiosis/anaerobiosis of S. oneidensis as well. Loss of ArcA, in addition to altering transcription of many genes, resulted in impaired growth under aerobic condition, which was not observed in E. coli. To further characterize the impact of ArcA loss on gene expression on the level of proteome under aerobic and anaerobic conditions, liquid-chromatography-mass-spectrometry (LC-MS) based proteomic approach was employed. Results show that ArcA loss led to globally altered gene expression, generally consistent with that observed with transcripts. Comparison of transcriptomic and proteomic data permitted identification of 17 high-confidence ArcA targets. Moreover, our data indicate that ArcA is required for regulation of cytochrome c proteins, and the menaquinone level may play a role in regulating ArcA as in E. coli. Proteomic-data-guided growth assay revealed that the aerobic growth defect of ArcA mutant is presumably due to impaired peptide utilization.

  5. Effects of three feedback conditions on aerobic swim speeds

    PubMed Central

    Pérez, Pedro; Llana, Salvador; Brizuela, Gabriel; Encarnación, Alberto

    2009-01-01

    The purpose of this study was twofold: (a) to develop an underwater chronometer capable to provide feedback while the athlete is swimming, as well as being a control tool for the coach, and (b) to analyse its feedback effect on swim pace control compared with feedback provided by the coach and with no feedback, in 25 m and 50 m swimming pools. 30 male swimmers of national level volunteer to participate. Each swimmer swam 3 x 200 m at aerobic speed (AS) and 3 x 200 m just under the anaerobic threshold speed (AnS), each swam repetition with a different feedback condition: chronometer, coach and without feedback. Results (a) validate the chronometer system developed and (b) show that swimmers pace control is affected by the type of feedback provided, the swim speed elected and the size of the swimming pool. Key points Providing concurrent feedback to swimmers improves theis swimming pace control. It is more important to provide feedback to control swim pace when the swimming pool is 50m long. Technological development as this chronometer system, could offload coach work, so coach can focus its time and attention on other performance aspects or other swimmers. Technological developments are more accepted by coaches when they don’t interfere on swimmers execution, that is, whet it is not necessary to implement the swimmer with cables and apparatus. PMID:24150553

  6. A performance evaluation of three membrane bioreactor systems: aerobic, anaerobic, and attached-growth.

    PubMed

    Achilli, A; Marchand, E A; Childress, A E

    2011-01-01

    Water sustainability is essential for meeting human needs for drinking water and sanitation in both developing and developed countries. Reuse, decentralization, and low energy consumption are key objectives to achieve sustainability in wastewater treatment. Consideration of these objectives has led to the development of new and tailored technologies in order to balance societal needs with the protection of natural systems. Membrane bioreactors (MBRs) are one such technology. In this investigation, a comparison of MBR performance is presented. Laboratory-scale submerged aerobic MBR (AMBR), anaerobic MBR (AnMBR), and attached-growth aerobic MBR (AtMBR) systems were evaluated for treating domestic wastewater under the same operating conditions. Long-term chemical oxygen demand (COD) and total organic carbon (TOC) monitoring showed greater than 80% removal in the three systems. The AnMBR system required three months of acclimation prior to steady operation, compared to one month for the aerobic systems. The AnMBR system exhibited a constant mixed liquor suspended solids concentration at an infinite solids retention time (i.e. no solids wasting), while the aerobic MBR systems produced approximately 0.25 g of biomass per gram of COD removed. This suggests a more economical solids management associated with the AnMBR system. Critical flux experiments were performed to evaluate fouling potential of the MBR systems. Results showed similar critical flux values between the AMBR and the AnMBR systems, while the AtMBR system showed relatively higher critical flux value. This result suggests a positive role of the attached-growth media in controlling membrane fouling in MBR systems. PMID:22049730

  7. Comparison of the transport and deposition of Pseudomonas aeruginosa under aerobic and anaerobic conditions

    NASA Astrophysics Data System (ADS)

    Zhang, Huixin; Zeng, Hongbo; Ulrich, Ania C.; Liu, Yang

    2016-02-01

    Laboratory-scale columns were employed to study the effect of oxygen and ionic strength on the transport of Pseudomonas aeruginosa PAO1 in porous media. In anaerobic experiments, cells were grown and transport experiments were conducted in a well-controlled anaerobic chamber. Cell surface electrokinetic potentials were measured and surface elemental composition was analyzed using X-ray photoelectron spectroscopy (XPS). Transport experimental results showed reduced travel distance of PAO1 with increased ionic strength under aerobic and anaerobic conditions, consistent with calculated Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. The deposition rates of PAO1 were significantly higher in aerobic than in anaerobic condition at higher ionic strength (10 and 100 mM), although the electrokinetic potentials were similar throughout the tested ionic strength (1, 10, and 100 mM). No difference in PAO1 deposition rate was observed at 1 mM. XPS analysis showed that variation in cell surface composition due to different growth conditions played a primary role in determining the different deposition behaviors.

  8. Effect of the process conditions of aerobic bioconversion on the characteristics of biologically processed brown coals

    SciTech Connect

    I.P. Ivanov

    2007-04-15

    The effect of the laboratory and pilot process conditions of the aerobic bioconversion of brown coals on the elemental composition and technical characteristics of the organic matter of the resulting biologically processed coals is reported.

  9. Aerobic Degradation of Trichloroethylene by Co-Metabolism Using Phenol and Gasoline as Growth Substrates

    PubMed Central

    Li, Yan; Li, Bing; Wang, Cui-Ping; Fan, Jun-Zhao; Sun, Hong-Wen

    2014-01-01

    Trichloroethylene (TCE) is a common groundwater contaminant of toxic and carcinogenic concern. Aerobic co-metabolic processes are the predominant pathways for TCE complete degradation. In this study, Pseudomonas fluorescens was studied as the active microorganism to degrade TCE under aerobic condition by co-metabolic degradation using phenol and gasoline as growth substrates. Operating conditions influencing TCE degradation efficiency were optimized. TCE co-metabolic degradation rate reached the maximum of 80% under the optimized conditions of degradation time of 3 days, initial OD600 of microorganism culture of 0.14 (1.26 × 107 cell/mL), initial phenol concentration of 100 mg/L, initial TCE concentration of 0.1 mg/L, pH of 6.0, and salinity of 0.1%. The modified transformation capacity and transformation yield were 20 μg (TCE)/mg (biomass) and 5.1 μg (TCE)/mg (phenol), respectively. Addition of nutrient broth promoted TCE degradation with phenol as growth substrate. It was revealed that catechol 1,2-dioxygenase played an important role in TCE co-metabolism. The dechlorination of TCE was complete, and less chlorinated products were not detected at the end of the experiment. TCE could also be co-metabolized in the presence of gasoline; however, the degradation rate was not high (28%). When phenol was introduced into the system of TCE and gasoline, TCE and gasoline could be removed at substantial rates (up to 59% and 69%, respectively). This study provides a promising approach for the removal of combined pollution of TCE and gasoline. PMID:24857922

  10. Aerobic degradation of trichloroethylene by co-metabolism using phenol and gasoline as growth substrates.

    PubMed

    Li, Yan; Li, Bing; Wang, Cui-Ping; Fan, Jun-Zhao; Sun, Hong-Wen

    2014-01-01

    Trichloroethylene (TCE) is a common groundwater contaminant of toxic and carcinogenic concern. Aerobic co-metabolic processes are the predominant pathways for TCE complete degradation. In this study, Pseudomonas fluorescens was studied as the active microorganism to degrade TCE under aerobic condition by co-metabolic degradation using phenol and gasoline as growth substrates. Operating conditions influencing TCE degradation efficiency were optimized. TCE co-metabolic degradation rate reached the maximum of 80% under the optimized conditions of degradation time of 3 days, initial OD600 of microorganism culture of 0.14 (1.26×10⁷ cell/mL), initial phenol concentration of 100 mg/L, initial TCE concentration of 0.1 mg/L, pH of 6.0, and salinity of 0.1%. The modified transformation capacity and transformation yield were 20 μg (TCE)/mg (biomass) and 5.1 μg (TCE)/mg (phenol), respectively. Addition of nutrient broth promoted TCE degradation with phenol as growth substrate. It was revealed that catechol 1,2-dioxygenase played an important role in TCE co-metabolism. The dechlorination of TCE was complete, and less chlorinated products were not detected at the end of the experiment. TCE could also be co-metabolized in the presence of gasoline; however, the degradation rate was not high (28%). When phenol was introduced into the system of TCE and gasoline, TCE and gasoline could be removed at substantial rates (up to 59% and 69%, respectively). This study provides a promising approach for the removal of combined pollution of TCE and gasoline. PMID:24857922

  11. Field assessment of semi-aerobic condition and the methane correction factor for the semi-aerobic landfills provided by IPCC guidelines

    SciTech Connect

    Jeong, Sangjae; Nam, Anwoo; Yi, Seung-Muk; Kim, Jae Young

    2015-02-15

    Highlights: • CH{sub 4}/CO{sub 2} and CH{sub 4} + CO{sub 2}% are proposed as indices to evaluate semi-aerobic landfills. • A landfill which CH{sub 4}/CO{sub 2} > 1.0 is difficult to be categorized as semi-aerobic landfill. • Field conditions should be carefully investigated to determine landfill types. • The MCF default value for semi-aerobic landfills underestimates the methane emissions. - Abstract: According to IPCC guidelines, a semi-aerobic landfill site produces one-half of the amount of CH{sub 4} produced by an equally-sized anaerobic landfill site. Therefore categorizing the landfill type is important on greenhouse gas inventories. In order to assess semi-aerobic condition in the sites and the MCF value for semi-aerobic landfill, landfill gas has been measured from vent pipes in five semi-aerobically designed landfills in South Korea. All of the five sites satisfied requirements of semi-aerobic landfills in 2006 IPCC guidelines. However, the ends of leachate collection pipes which are main entrance of air in the semi-aerobic landfill were closed in all five sites. The CH{sub 4}/CO{sub 2} ratio in landfill gas, indicator of aerobic and anaerobic decomposition, ranged from 1.08 to 1.46 which is higher than the values (0.3–1.0) reported for semi-aerobic landfill sites and is rather close to those (1.0–2.0) for anaerobic landfill sites. The low CH{sub 4} + CO{sub 2}% in landfill gas implied air intrusion into the landfill. However, there was no evidence that air intrusion has caused by semi-aerobic design and operation. Therefore, the landfills investigated in this study are difficult to be classified as semi-aerobic landfills. Also MCF of 0.5 may significantly underestimate methane emissions compared to other researches. According to the carbon mass balance analyses, the higher MCF needs to be proposed for semi-aerobic landfills. Consequently, methane emission estimate should be based on field evaluation for the semi-aerobically designed landfills.

  12. Degradation of municipal solid waste in simulated landfill bioreactors under aerobic conditions.

    PubMed

    Slezak, Radoslaw; Krzystek, Liliana; Ledakowicz, Stanislaw

    2015-09-01

    In this study the municipal solid waste degradation processes in simulated landfill bioreactors under aerobic and anaerobic conditions is investigated. The effect of waste aeration on the dynamics of the aerobic degradation processes in lysimeters as well as during anaerobic processes after completion of aeration is presented. The results are compared with the anaerobic degradation process to determine the stabilization stage of waste in both experimental modes. The experiments in aerobic lysimeters were carried out at small aeration rate (4.41⋅10(-3)lmin(-1)kg(-1)) and for two recirculation rates (24.9 and 1.58lm(-3)d(-1)). The change of leachate and formed gases composition showed that the application of even a small aeration rate favored the degradation of organic matter. The amount of CO2 and CH4 released from anaerobic lysimeter was about 5 times lower than that from the aerobic lysimeters. Better stabilization of the waste was obtained in the aerobic lysimeter with small recirculation, from which the amount of CO2 produced was larger by about 19% in comparison with that from the aerobic lysimeter with large leachate recirculation. PMID:26119011

  13. Nitrous oxide production by Alcaligenes faecalis under transient and dynamic aerobic and anaerobic conditions

    SciTech Connect

    Otte, S.; Grobben, N.G.; Robertson, L.A.; Jetten, M.S.M.; Kuenen, J.G.

    1996-07-01

    Nitrous oxide production contributes to both greenhouse effect and ozone depletion in the stratosphere. A significant part of the global N2O emission can be attributed to microbial processes, especially nitrification and denitrification, used in biological wastewater treatment systems. This study looks at the efficiency of denitrification and the enzymes involved, with the emphasis on N2O production during the transient phase from aerobic to anaerobic conditions and vice versa. The effect of repetitive changing aerobic-anaerobic conditions on N2O was also studied. Alcaligenes faecalis was used as the model denitrofing organism. 35 refs., 3 figs., 1 tab.

  14. Enhanced performance of denitrifying sulfide removal process under micro-aerobic condition.

    PubMed

    Chen, Chuan; Ren, Nanqi; Wang, Aijie; Liu, Lihong; Lee, Duu-Jong

    2010-07-15

    The denitrifying sulfide removal (DSR) process with bio-granules comprising both heterotrophic and autotrophic denitrifiers can simultaneously convert nitrate, sulfide and acetate into di-nitrogen gas, elementary sulfur and carbon dioxide, respectively, at high loading rates. This study determines the reaction rate of sulfide oxidized into sulfur, as well as the reduction of nitrate to nitrite, would be enhanced under a micro-aerobic condition. The presence of limited oxygen mitigated the inhibition effects of sulfide on denitrifier activities, and enhanced the performance of DSR granules. The advantages and disadvantages of applying the micro-aerobic condition to the DSR process are discussed. PMID:20233637

  15. Optimum conditions for aerobic thermophilic pretreatment of municipal sludge

    SciTech Connect

    Cheunbarn, T.; Pagilla, K.R.

    1998-07-01

    Lab scale experiments were conducted to determine optimum sludge residence time (SRT) and temperature of aerobic thermophilic pretreatment (ATP) of mixed (thickened waste activated and primary) sludge to achieve maximum pathogen destruction and best process performance. 4L lab scale ATP reactors were operated at SRT of 0.6, 1.0, and 1.5 days, and at temperature of 55, 58, 62 and 65 C. ATP at temperature {ge} 62 C and SRT {ge} 0.6 days reduced the feed sludge fecal coliform density by at least 4-logs from 10{sup 7} MPN/g total solids to < 10{sup 4} MPN/g total solids. Salmonella in the feed sludge was reduced to < 1 MPN/g total solids from 2 to 18 MPN/4 g total solids by ATP at temperature {ge} 55 C and SRT {ge} 0.6 days. ATP was able to increase sludge volatile acids concentration by 100--200% over the feed sludge volatile acid concentration, and reduce the supernatant COD from 20,000--22,000 mg/L in the feed to 13,000--17,000 mg/L in ATP reactor sludge. Volatile solids destruction by ATP was increased from 25% to 40% when SRT was increased from 0.6 days to 1.5 days, and only 5% increase in volatile solids destruction was seen at each SRT of 0.6, 1.0, and 1.5 days when ATP temperature was increased from 55 to 65 C.

  16. Differential Isotopic Fractionation during Cr(VI) Reduction by an Aquifer-Derived Bacterium under Aerobic versus Denitrifying Conditions

    PubMed Central

    Han, Ruyang; Qin, Liping; Brown, Shaun T.; Christensen, John N.

    2012-01-01

    We studied Cr isotopic fractionation during Cr(VI) reduction by Pseudomonas stutzeri strain RCH2. Despite the fact that strain RCH2 reduces Cr(VI) cometabolically under both aerobic and denitrifying conditions and at similar specific rates, fractionation was markedly different under these two conditions (ε was ∼2‰ aerobically and ∼0.4‰ under denitrifying conditions). PMID:22286991

  17. Differential Isotopic Fractionation during Cr(VI) Reduction by an Aquifer-Derived Bacterium under Aerobic versus Denitrifying Conditions

    SciTech Connect

    Han, R.; Qin, L.; Brown, S. T.; Christensen, J. N.; Beller, H. R.

    2012-01-27

    We studied Cr isotopic fractionation during Cr(VI) reduction by Pseudomonas stutzeri strain RCH2. Finally, despite the fact that strain RCH2 reduces Cr(VI) cometabolically under both aerobic and denitrifying conditions and at similar specific rates, fractionation was markedly different under these two conditions (ε was ~2‰ aerobically and ~0.4‰ under denitrifying conditions).

  18. Decomposition Dynamics and Changes in Chemical Composition of Wheat Straw Residue under Anaerobic and Aerobic Conditions.

    PubMed

    Gao, Hongjian; Chen, Xi; Wei, Junling; Zhang, Yajie; Zhang, Ligan; Chang, Jiang; Thompson, Michael L

    2016-01-01

    Soil aeration is a crucial factor that regulates crop residue decomposition, and the chemical composition of decomposing crop residues may change the forms and availability of soil nutrients, such as N and P. However, to date, differences in the chemical composition of crop straw residues after incorporation into soil and during its decomposition under anaerobic vs. aerobic conditions have not been well documented. The objective of the present study was to assess changes in the C-containing functional groups of wheat straw residue during its decomposition in anaerobic and aerobic environments. A 12-month incubation experiment was carried out to investigate the temporal variations of mass, carbon, and nitrogen loss, as well as changes in the chemical composition of wheat (Triticum aestivum L) straw residues under anaerobic and aerobic conditions by measuring C-containing functional groups using solid state nuclear magnetic resonance (NMR) spectroscopy. The residual mass, carbon content, and nitrogen content of the straw residue sharply declined during the initial 3 months, and then slowly decreased during the last incubation period from 3 to 12 months. The decomposition rate constant (k) for mass loss under aerobic conditions (0.022 d-1) was higher than that under anaerobic conditions (0.014 d-1). The residual mass percentage of cellulose and hemicellulose in the wheat straw gradually declined, whereas that of lignin gradually increased during the entire 12-month incubation period. The NMR spectra of C-containing functional groups in the decomposing straw under both aerobic and anaerobic conditions were similar at the beginning of the incubation as well as at 1 month, 6 months, and 12 months. The main alterations in C-containing functional groups during the decomposition of wheat straw were a decrease in the relative abundances of O-alkyl C and an increase in the relative abundances of alkyl C, aromatic C and COO/N-C = O functional groups. The NMR signals of alkyl C

  19. Decomposition Dynamics and Changes in Chemical Composition of Wheat Straw Residue under Anaerobic and Aerobic Conditions

    PubMed Central

    Gao, Hongjian; Chen, Xi; Wei, Junling; Zhang, Yajie; Zhang, Ligan; Chang, Jiang; Thompson, Michael L.

    2016-01-01

    Soil aeration is a crucial factor that regulates crop residue decomposition, and the chemical composition of decomposing crop residues may change the forms and availability of soil nutrients, such as N and P. However, to date, differences in the chemical composition of crop straw residues after incorporation into soil and during its decomposition under anaerobic vs. aerobic conditions have not been well documented. The objective of the present study was to assess changes in the C-containing functional groups of wheat straw residue during its decomposition in anaerobic and aerobic environments. A 12-month incubation experiment was carried out to investigate the temporal variations of mass, carbon, and nitrogen loss, as well as changes in the chemical composition of wheat (Triticum aestivum L) straw residues under anaerobic and aerobic conditions by measuring C-containing functional groups using solid state nuclear magnetic resonance (NMR) spectroscopy. The residual mass, carbon content, and nitrogen content of the straw residue sharply declined during the initial 3 months, and then slowly decreased during the last incubation period from 3 to 12 months. The decomposition rate constant (k) for mass loss under aerobic conditions (0.022 d-1) was higher than that under anaerobic conditions (0.014 d-1). The residual mass percentage of cellulose and hemicellulose in the wheat straw gradually declined, whereas that of lignin gradually increased during the entire 12-month incubation period. The NMR spectra of C-containing functional groups in the decomposing straw under both aerobic and anaerobic conditions were similar at the beginning of the incubation as well as at 1 month, 6 months, and 12 months. The main alterations in C-containing functional groups during the decomposition of wheat straw were a decrease in the relative abundances of O-alkyl C and an increase in the relative abundances of alkyl C, aromatic C and COO/N-C = O functional groups. The NMR signals of alkyl C

  20. Effect of bicarbonate concentration on aerobic growth of campylobacter in a fumarate-pyruvate medium

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The purpose of the present study was to examine the effect of sodium bicarbonate (NaHCO3) concentration on aerobic growth of Campylobacter in a fumarate-pyruvate medium. Fumarate-pyruvate broth medium was supplemented with 0.00 to 0.10% NaHCO3 and inoculated with Campylobacter coli 33559, Campyloba...

  1. Enhancing Aerobic Growth of Campylobacter in Media Supplemented with Organic Acids

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effect of agar and sodium bicarbonate (NaHCO3) concentration on aerobic growth of Campylobacter in was determined. A fumarate-pyruvate medium was supplemented with 0.0 to 0.2% agar and inoculated with Campylobacter coli, Campylobacter fetus, or Campylobacter jejuni. Portions of the inoculated me...

  2. Nesterenkonia sp. strain F, a halophilic bacterium producing acetone, butanol, and ethanol under aerobic conditions

    PubMed Central

    Amiri, Hamid; Azarbaijani, Reza; Parsa Yeganeh, Laleh; Shahzadeh Fazeli, Abolhassan; Tabatabaei, Meisam; Hosseini Salekdeh, Ghasem; Karimi, Keikhosro

    2016-01-01

    The moderately halophilic bacterium Nesterenkonia sp. strain F, which was isolated from Aran-Bidgol Lake (Iran), has the ability to produce acetone, butanol, and ethanol (ABE) as well as acetic and butyric acids under aerobic and anaerobic conditions. This result is the first report of ABE production with a wild microorganism from a family other than Clostridia and also the first halophilic species shown to produce butanol under aerobic cultivation. The cultivation of Nesterenkonia sp. strain F under anaerobic conditions with 50 g/l of glucose for 72 h resulted in the production of 105 mg/l of butanol, 122 mg/l of acetone, 0.2 g/l of acetic acid, and 2.5 g/l of butyric acid. Furthermore, the strain was cultivated on media with different glucose concentrations (20, 50, and 80 g/l) under aerobic and anaerobic conditions. Through fermentation with a 50 g/l initial glucose concentration under aerobic conditions, 66 mg/l of butanol, 125 mg/l of acetone, 291 mg/l of ethanol, 5.9 g/l of acetic acid, and 1.2 g/l of butyric acid were produced. The enzymes pertaining to the fermentation pathway in the strain were compared with the enzymes of Clostridium spp., and the metabolic pathway of fermentation used by Nesterenkonia sp. strain F was investigated. PMID:26725518

  3. Nesterenkonia sp. strain F, a halophilic bacterium producing acetone, butanol, and ethanol under aerobic conditions.

    PubMed

    Amiri, Hamid; Azarbaijani, Reza; Parsa Yeganeh, Laleh; Shahzadeh Fazeli, Abolhassan; Tabatabaei, Meisam; Salekdeh, Ghasem Hosseini; Karimi, Keikhosro

    2016-01-01

    The moderately halophilic bacterium Nesterenkonia sp. strain F, which was isolated from Aran-Bidgol Lake (Iran), has the ability to produce acetone, butanol, and ethanol (ABE) as well as acetic and butyric acids under aerobic and anaerobic conditions. This result is the first report of ABE production with a wild microorganism from a family other than Clostridia and also the first halophilic species shown to produce butanol under aerobic cultivation. The cultivation of Nesterenkonia sp. strain F under anaerobic conditions with 50 g/l of glucose for 72 h resulted in the production of 105 mg/l of butanol, 122 mg/l of acetone, 0.2 g/l of acetic acid, and 2.5 g/l of butyric acid. Furthermore, the strain was cultivated on media with different glucose concentrations (20, 50, and 80 g/l) under aerobic and anaerobic conditions. Through fermentation with a 50 g/l initial glucose concentration under aerobic conditions, 66 mg/l of butanol, 125 mg/l of acetone, 291 mg/l of ethanol, 5.9 g/l of acetic acid, and 1.2 g/l of butyric acid were produced. The enzymes pertaining to the fermentation pathway in the strain were compared with the enzymes of Clostridium spp., and the metabolic pathway of fermentation used by Nesterenkonia sp. strain F was investigated. PMID:26725518

  4. Isolation of microorganisms capable of degrading isoquinoline under aerobic conditions

    SciTech Connect

    Aislabie, J.; Rothenburger, S.; Atlas, R.M. )

    1989-12-01

    Isoquinoline-degrading microbial cultures were isolated from oil- and creosote-contaminated soils. The establishment of initial enrichment cultures required the use of emulsified isoquinoline. Once growth on isoquinoline was established, isoquinoline emulsification was no longer required for utilization of isoquinoline as the sole source of carbon and nitrogen by these cultures. An isoquinoline-degrading Acinetobacter strain was isolated from one of the enrichment cultures. The degradation of isoquinoline was accompanied by the accumulation of a red cell-associated pigment and of 1-hydroxyisoquinoline, which was further degraded to unknown intermediary ring-cleavage products and carbon dioxide.

  5. Aerobic glycolysis in the primate brain: reconsidering the implications for growth and maintenance.

    PubMed

    Bauernfeind, Amy L; Barks, Sarah K; Duka, Tetyana; Grossman, Lawrence I; Hof, Patrick R; Sherwood, Chet C

    2014-07-01

    Glucose metabolism produces, by oxidative phosphorylation, more than 15 times the amount of energy generated by aerobic glycolysis. Nonetheless, aerobic glycolysis remains a prevalent metabolic pathway in the brain. Here we review evidence suggesting that this pathway contributes essential molecules to the biomass of the brain. Aerobic metabolism is the dominant metabolic pathway during early postnatal development when lipids and proteins are needed for the processes of axonal elongation, synaptogenesis, and myelination. Furthermore, aerobic metabolism may continue into adulthood to supply biomolecules for activity-related changes at the synapse and turnover of constituent structural components of neurons. Conversely, oxidative phosphorylation appears to be the main metabolic support for synaptic transmission, and, therefore, this pathway seems to be more dominant in brain structures and at time points in the lifespan that are characterized by increased synaptic density. We present the case for differing relationships between aerobic glycolysis and oxidative phosphorylation across primates in association with species-specific variation in neurodevelopmental trajectories. In doing so, we provide an alternative interpretation for the assessment of radiolabeled glucose positron emission tomography studies that regularly attribute increases in glucose uptake to neural activity alone, and propose a new model for the contribution of metabolic pathways for energetic demand and neural tissue growth. We conclude that comparative studies of metabolic appropriation in the brain may contribute to the discussion of human cognitive evolution and to the understanding of human-specific aging and the etiology of neuropsychiatric diseases. PMID:24185460

  6. Mathematical model for the aerobic growth of saccharomyces cerevisiae with a saturated respiratory capacity

    SciTech Connect

    Barford, J.P.; Hall, R.J.

    1981-08-01

    A mathematical model for the aerobic growth of Saccharomyces cerevisiae in both batch and continuous culture is described. It was based on the experimental observation that the respiratory capacity of this organism may become saturated and exhibit a maximum specific oxygen uptake rate after suitable adaptation. This experimental observation led to the possibility that transport into and out of the mitochondrion was of major importance in the overall metabolism of S. cerevisiae and was subject to long-term adaptation. Consistent with this observation a distributed model was proposed which, as its basis, assumed the control of respiration and fermentation to be the result of saturation of respiration without any specific repression or inhibition of the uptake rates of other substrates. No other regulation of fermentation and respiration was assumed. The model provided a suitable structure allowing precise quantification of the changes in rate and stoichiometry of energy production. The model clearly indicated that growth under the wide range of experimental conditions reported could not be predicted using constant values for the maximum specific respiratory rate or constant values of Yatp (g biomass/mol ATP) and PO ratio of (mol ATP/atom oxygen). The causes of the variation in the respiratory rate were not determined and it was concluded that a more detailed analysis (reported subsequently) was required. The variation of Y atp and PO ratio with specific growth rate implied that the efficiency of ATP generation or ATP utilization decreased with increasing specific growth rate. It was concluded that it was not possible to quantify the individual effect of Yatp and PO ratio until independent means for their reliable estimation is available. (Refs. 84).

  7. Production of wax esters during aerobic growth of marine bacteria on isoprenoid compounds

    PubMed

    Rontani; Bonin; Volkman

    1999-01-01

    This paper describes the production of isoprenoid wax esters during the aerobic degradation of 6,10,14-trimethylpentadecan-2-one and phytol by four bacteria (Acinetobacter sp. strain PHY9, Pseudomonas nautica [IP85/617], Marinobacter sp. strain CAB [DSMZ 11874], and Marinobacter hydrocarbonoclasticus [ATCC 49840]) isolated from the marine environment. Different pathways are proposed to explain the formation of these compounds. In the case of 6,10, 14-trimethylpentadecan-2-one, these esters result from the condensation of some acidic and alcoholic metabolites produced during the biodegradation, while phytol constitutes the alcohol moiety of most of the esters produced during growth on this isoprenoid alcohol. The amount of these esters formed increased considerably in N-limited cultures, in which the ammonium concentration corresponds to conditions often found in marine sediments. This suggests that the bacterial formation of isoprenoid wax esters might be favored in such environments. Although conflicting evidence exists regarding the stability of these esters in sediments, it seems likely that, under some conditions, bacterial esterification can enhance the preservation potential of labile compounds such as phytol. PMID:9872783

  8. Comparison of sludge digestion under aerobic and anaerobic conditions with a focus on the degradation of proteins at mesophilic temperature.

    PubMed

    Shao, Liming; Wang, Tianfeng; Li, Tianshui; Lü, Fan; He, Pinjing

    2013-07-01

    Aerobic and anaerobic digestion are popular methods for the treatment of waste activated sludge. However, the differences in degradation of sludge during aerobic and anaerobic digestion remain unclear. In this study, the sludge degradation during aerobic and anaerobic digestion was investigated at mesophilic temperature, focused on protein based on the degradation efficiency and degree of humification. The duration of aerobic and anaerobic digestion was about 90 days. The final degradation efficiency of volatile solid was 66.1 ± 1.6% and 66.4 ± 2.4% under aerobic and anaerobic conditions, respectively. The final degradation efficiency of protein was 67.5 ± 1.4% and 65.1 ± 2.6% under aerobic and anaerobic conditions, respectively. The degradation models of volatile solids were consistent with those of protein under both aerobic and anaerobic conditions. The solubility of protein under aerobic digestion was greater than that under anaerobic digestion. Moreover, the humification index of dissolved organic matter of aerobic digestion was greater than that during anaerobic digestion. PMID:23685650

  9. Role of phosphate solubilizing bacteria on rock phosphate solubility and growth of aerobic rice.

    PubMed

    Panhwar, Q A; Radziah, O; Zaharah, A R; Sariah, M; Razi, I Mohd

    2011-09-01

    Use of phosphate-solubilizing bacteria (PSB) as inoculants has concurrently increased phosphorous uptake in plants and improved yields in several crop species. The ability of PSB to improve growth of aerobic rice (Oryza sativa L.) through enhanced phosphorus (P) uptake from Christmas island rock phosphate (RP) was studied in glasshouse experiments. Two isolated PSB strains; Bacillus spp. PSB9 and PSB16, were evaluated with RP treatments at 0, 30 and 60 kg ha(-1). Surface sterilized seeds of aerobic rice were planted in plastic pots containing 3 kg soil and the effect of treatments incorporated at planting were observed over 60 days of growth. The isolated PSB strains (PSB9 and PSB16) solubilized significantly high amounts of P (20.05-24.08 mg kg(-1)) compared to non-inoculated (19-23.10 mg kg(-1)) treatments. Significantly higher P solubilization (24.08 mg kg(-1)) and plant P uptake (5.31 mg plant(-1)) was observed with the PSB16 strain at the highest P level of 60 kg ha(-1). The higher amounts of soluble P in the soil solution increased P uptake in plants and resulted in higher plant biomass (21.48 g plant(-1)). PSB strains also increased plant height (80 cm) and improved root morphology in aerobic rice. The results showed that inoculation of aerobic rice with PSB improved phosphate solubilizing activity of incorporated RP. PMID:22319876

  10. The effect of aerobic exercise and starvation on growth performance and postprandial metabolic response in juvenile southern catfish (Silurus meridionalis).

    PubMed

    Li, Xiu-Ming; Liu, Li; Yuan, Jian-Ming; Xiao, Yuan-Yuan; Fu, Shi-Jian; Zhang, Yao-Guang

    2016-03-01

    To investigate the effects of aerobic exercise and starvation on growth performance, postprandial metabolic response and their interaction in a sedentary fish species, either satiation-fed or starved juvenile southern catfish (Silurus meridionalis) were exercised at 25 °C under three water velocities, i.e., nearly still water (control), 1 body length (bl) s(-1) and 2 bl s(-1), for eight weeks. Then, the feed intake (FI), food conversion efficiency (FCE), specific growth rate (SGR), morphological parameters, resting ṀO2 (ṀO2rest) and postprandial ṀO2 responses of the experimental fish were measured. Exercise at a low velocity (1 bl s(-1)) showed no effect on any growth performance parameter, whereas exercise at a high velocity (2 bl s(-1)) exhibited higher FI but similar SGR due to the extra energy expenditure from swimming and consequent decreased FCE. Starvation led to a significant body mass loss, whereas the effect intensified in both exercise groups. Exercise resulted in improved cardio-respiratory capacity, as indicated by increased gill and heart indexes, whereas it exhibited no effect on resting and postprandial metabolism in S. meridionalis. The starved fish displayed significantly larger heart, gill and digestive tract indexes compared with the feeding fish, suggesting selective maintenance of cardio-respiratory and digestive function in this fish species during starvation. However, starved fish still exhibited impaired digestive performance, as evidenced by the prolonged duration and low postprandial metabolic increase, and this effect was further exacerbated in both the 1 and 2 bl s(-1) exercise groups. These data suggest the following: (1) aerobic exercise produced no improvement in growth performance but may have led to the impairment of growth under insufficient food conditions; (2) the mass of different organs and tissues responded differently to aerobic exercise and starvation due to the different physiological roles they play; and (3

  11. Reductive dechlorination of Tri- and tetrachloroethylenes depends on transition from aerobic to anaerobic conditions.

    PubMed Central

    Kästner, M

    1991-01-01

    Aerobic enrichment cultures from contaminated groundwaters dechlorinated trichloroethylene (TCE) (14.6 mg/liter; 111 mumol/liter) and tetrachloroethylene (PCE) (16.2 mg/liter; 98 mumol/liter) reductively within 4 days after the transition from aerobic to anaerobic conditions. The transformation products were equimolar amounts of cis-1,2-dichloroethylene and traces of 1,1-dichloroethylene. No other chlorinated product and no methane were detected. The change was accompanied by the release of sulfide, which caused a decrease in the redox potential from 0 to -150 mV. In sterile control experiments, sulfide led to the abiotic formation of traces of 1,1-dichloroethylene without cis-1,2-dichloroethylene production. The reductive dechlorination of PCE via TCE depended on these specific transition conditions after consumption of the electron acceptor oxygen or nitrate. Repeated feeding of TCE or PCE to cultures after the change to anaerobic conditions yielded no further dechlorination. Only aerobic subcultures with an air/liquid ratio of 1:4 maintained dechlorination activities; anaerobic subcultures showed no transformation. Bacteria from noncontaminated sites showed no reduction under the same conditions. PMID:1892393

  12. Reductive dechlorination of Tri- and tetrachloroethylenes depends on transition from aerobic to anaerobic conditions.

    PubMed

    Kästner, M

    1991-07-01

    Aerobic enrichment cultures from contaminated groundwaters dechlorinated trichloroethylene (TCE) (14.6 mg/liter; 111 mumol/liter) and tetrachloroethylene (PCE) (16.2 mg/liter; 98 mumol/liter) reductively within 4 days after the transition from aerobic to anaerobic conditions. The transformation products were equimolar amounts of cis-1,2-dichloroethylene and traces of 1,1-dichloroethylene. No other chlorinated product and no methane were detected. The change was accompanied by the release of sulfide, which caused a decrease in the redox potential from 0 to -150 mV. In sterile control experiments, sulfide led to the abiotic formation of traces of 1,1-dichloroethylene without cis-1,2-dichloroethylene production. The reductive dechlorination of PCE via TCE depended on these specific transition conditions after consumption of the electron acceptor oxygen or nitrate. Repeated feeding of TCE or PCE to cultures after the change to anaerobic conditions yielded no further dechlorination. Only aerobic subcultures with an air/liquid ratio of 1:4 maintained dechlorination activities; anaerobic subcultures showed no transformation. Bacteria from noncontaminated sites showed no reduction under the same conditions. PMID:1892393

  13. P450-catalyzed asymmetric cyclopropanation of electron-deficient olefins under aerobic conditions.

    PubMed

    Renata, Hans; Wang, Z Jane; Kitto, Rebekah Z; Arnold, Frances H

    2014-10-01

    A variant of P450 from Bacillus megaterium five mutations away from wild type is a highly active catalyst for cyclopropanation of a variety of acrylamide and acrylate olefins with ethyl diazoacetate (EDA). The very high rate of reaction enabled by histidine ligation allowed the reaction to be conducted under aerobic conditions. The promiscuity of this catalyst for a variety of substrates containing amides has enabled synthesis of a small library of precursors to levomilnacipran derivatives. PMID:25221671

  14. P450-catalyzed asymmetric cyclopropanation of electron-deficient olefins under aerobic conditions

    PubMed Central

    Renata, Hans; Wang, Z. Jane; Kitto, Rebekah Z.

    2014-01-01

    A variant of P450 from Bacillus megaterium five mutations away from wild type is a highly active catalyst for cyclopropanation of a variety of acrylamide and acrylate olefins with ethyl diazoacetate (EDA). The very high rate of reaction enabled by histidine ligation allowed the reaction to be conducted under aerobic conditions. The promiscuity of this catalyst for a variety of substrates containing amides has enabled synthesis of a small library of precursors to levomilnacipran derivatives. PMID:25221671

  15. Reduced expression of cytochrome oxidases largely explains cAMP inhibition of aerobic growth in Shewanella oneidensis

    PubMed Central

    Yin, Jianhua; Meng, Qiu; Fu, Huihui; Gao, Haichun

    2016-01-01

    Inhibition of bacterial growth under aerobic conditions by elevated levels of cyclic adenosine 3′,5′-monophosphate (cAMP), first revealed more than 50 years ago, was attributed to accumulation of toxic methylglyoxal (MG). Here, we report a Crp-dependent mechanism rather than MG accumulation that accounts for the phenotype in Shewanella oneidensis, an emerging research model for the bacterial physiology. We show that a similar phenotype can be obtained by removing CpdA, a cAMP phosphodiesterase that appears more effective than its Escherichia coli counterpart. Although production of heme c and cytochromes c is correlated well with cAMP levels, neither is sufficient for the retarded growth. Quantities of overall cytochromes c increased substantially in the presence of elevated cAMP, a phenomenon resembling cells respiring on non-oxygen electron acceptors. In contrast, transcription of Crp-dependent genes encoding both cytochromes bd and cbb3 oxidases is substantially repressed under the same condition. Overall, our results suggest that cAMP of elevated levels drives cells into a low-energetic status, under which aerobic respiration is inhibited. PMID:27076065

  16. Aerobic capacity in wild satin bowerbirds: repeatability and effects of age, sex and condition.

    PubMed

    Chappell, Mark A; Savard, Jean-Francois; Siani, Jennifer; Coleman, Seth W; Keagy, Jason; Borgia, Gerald

    2011-10-01

    Individual variation in aerobic capacity has been extensively studied, especially with respect to condition, maturity or pathogen infection, and to gain insights into mechanistic foundations of performance. However, its relationship to mate competition is less well understood, particularly for animals in natural habitats. We examined aerobic capacity [maximum rate of O2 consumption (VO2,max) in forced exercise] in wild satin bowerbirds, an Australian passerine with a non-resource based mating system and strong intermale sexual competition. We tested for repeatability of mass and VO2,max, differences among age and sex classes, and effects of several condition indices. In adult males, we examined interactions between aerobic performance and bower ownership (required for male mating success). There was significant repeatability of mass and VO2,max within and between years, but between-year repeatability was lower than within-year repeatability. VO2,max varied with an overall scaling to mass(0.791), but most variance in VO2,max was not explained by mass. Indicators of condition (tarsus and wing length asymmetry, the ratio of tarsus length to mass) were not correlated to VO2,max. Ectoparasite counts were weakly correlated to VO2,max across all age-sex classes but not within any class. Adult males, the cohort with the most intense levels of mating competition, had higher VO2,max than juvenile birds or adult females. However, there was no difference between the VO2,max of bower-owning males and that of males not known to hold bowers. Thus one major factor determining male reproductive success was not correlated to aerobic performance. PMID:21900466

  17. Aerobic thermophilic treatment of sewage sludge at pilot plant scale. 1. Operating conditions.

    PubMed

    Ponti, C; Sonnleitner, B; Fiechter, A

    1995-01-15

    The aerobic thermophilic treatment process of sewage sludge was studied at different bioreactor scales in a pilot plant installation. Since, for a satisfactory sludge disinfection, the Swiss legislation requires minimal incubation times of all volume elements, the bioreactors were operated in repetitive batch mode (draw and fill). Different retention times and frequencies of the volume changes were applied in order to prove the capability of the particular operation modes in assuring high degradative potential. The main enzymatic activity involved during the aerobic treatment was proteolysis: the RQ values ranged between 0.8 and 0.9 depending on the applied operating conditions. Although not in a linear manner, the efficiency of the microflora decreased as the bioreactor scale increased, when this increase corresponded with a reduction of the specific power input. The sludge oxidation rates can be tuned by some process operating conditions such as the volume change frequency, the changed volume quantities and the retention times. It was possible to improve the microbial degradative efficiency by an increased frequency of the changes, while the mean retention time influenced in particular the ultimate product quality, described as residual organic matter content of the sludge. The microflora present was also satisfactorily active at mean hydraulic retention times of less than 10 h. The organic matter concentration of the inlet sewage sludge plays an important role: it influences the aerobic degradation process positively. PMID:7765808

  18. Model based evaluation of a contaminant plume development under aerobic and anaerobic conditions in 2D bench-scale tank experiments.

    PubMed

    Ballarini, E; Beyer, C; Bauer, R D; Griebler, C; Bauer, S

    2014-06-01

    The influence of transverse mixing on competitive aerobic and anaerobic biodegradation of a hydrocarbon plume was investigated using a two-dimensional, bench-scale flow-through laboratory tank experiment. In the first part of the experiment aerobic degradation of increasing toluene concentrations was carried out by the aerobic strain Pseudomonas putida F1. Successively, ethylbenzene (injected as a mixture of unlabeled and fully deuterium-labeled isotopologues) substituted toluene; nitrate was added as additional electron acceptor and the anaerobic denitrifying strain Aromatoleum aromaticum EbN1 was inoculated to study competitive degradation under aerobic /anaerobic conditions. The spatial distribution of anaerobic degradation was resolved by measurements of compound-specific stable isotope fractionation induced by the anaerobic strain as well as compound concentrations. A fully transient numerical reactive transport model was employed and calibrated using measurements of electron donors, acceptors and isotope fractionation. The aerobic phases of the experiment were successfully reproduced using a double Monod kinetic growth model and assuming an initial homogeneous distribution of P. putida F1. Investigation of the competitive degradation phase shows that the observed isotopic pattern cannot be explained by transverse mixing driven biodegradation only, but also depends on the inoculation process of the anaerobic strain. Transient concentrations of electron acceptors and donors are well reproduced by the model, showing its ability to simulate transient competitive biodegradation. PMID:24122285

  19. Conditioning biomass for microbial growth

    SciTech Connect

    Bodie, Elizabeth A; England, George

    2015-03-31

    The present invention relates to methods for improving the yield of microbial processes that use lignocellulose biomass as a nutrient source. The methods comprise conditioning a composition comprising lignocellulose biomass with an enzyme composition that comprises a phenol oxidizing enzyme. The conditioned composition can support a higher rate of growth of microorganisms in a process. In one embodiment, a laccase composition is used to condition lignocellulose biomass derived from non-woody plants, such as corn and sugar cane. The invention also encompasses methods for culturing microorganisms that are sensitive to inhibitory compounds in lignocellulose biomass. The invention further provides methods of making a product by culturing the production microorganisms in conditioned lignocellulose biomass.

  20. By reducing hexokinase 2, resveratrol induces apoptosis in HCC cells addicted to aerobic glycolysis and inhibits tumor growth in mice

    PubMed Central

    Xia, Yujing; He, Lei; Chen, Kan; Li, Jingjing; Li, Sainan; Liu, Tong; Zheng, Yuanyuan; Wang, Jianrong; Lu, Wenxia; Zhou, Yuqing; Yin, Qin; Abudumijiti, Huerxidan; Chen, Rongxia; Zhang, Rong; Zhou, Li; Zhou, Zheng; Zhu, Rong; Yang, Jing; Wang, Chengfen; Zhang, Huawei; Zhou, Yingqun; Xu, Ling; Guo, Chuanyong

    2015-01-01

    Cancer cells exhibit an altered metabolic phenotype known as the aerobic glycolysis. The expression of HK2 changes the metabolic phenotype of cells to support cancerous growth. In the present study, we investigated the inhibitory effect of resveratrol on HK2 expression and hepatocellular carcinoma (HCC) cell glycolysis. Aerobic glycolysis was observed in four HCC cell lines compared to the normal hepatic cells. Resveratrol sensitized aerobic glycolytic HCC cells to apoptosis, and this effect was attenuated by glycolytic inhibitors. The induction of mitochondrial apoptosis was associated with the decrease of HK2 expression by resveratrol in HCC cells. In addition, resveratrol enhanced sorafenib induced cell growth inhibition in aerobic glycolytic HCC cells. Combination treatment with both reagents inhibited the growth and promoted apoptosis of HCC-bearing mice. The reduction of HK2 by resveratrol provides a new dimension to clinical HCC therapies aimed at preventing disease progression. PMID:25938543

  1. Laboratory degradation rates of 11 pyrethroids under aerobic and anaerobic conditions.

    PubMed

    Meyer, Brian N; Lam, Chung; Moore, Sean; Jones, Russell L

    2013-05-22

    Degradation of 11 pyrethroids was measured over approximately 100 days in three sediment/water systems under aerobic and anaerobic conditions at 25 °C in the dark. The three California sediments represented a range of textures and organic matter. Test compounds were bifenthrin, cypermethrin, ζ-cypermethrin, cyfluthrin, β-cyfluthrin, deltamethrin, esfenvalerate, fenpropathrin, γ-cyhalothrin, λ-cyhalothrin, and permethrin. A non-standard design was employed to keep conditions essentially the same for all compounds. The test compounds were applied as two test mixtures (six active ingredients per mixture, with bifenthrin common to both) at approximately 50 μg of test compound/kg of sediment (dry weight). Extracts of sediment/water were cleaned up by solid-phase extraction, concentrated, and analyzed by gas chromatography/mass spectrometry (except deltamethrin) against matrix-matched standards, with cyfluthrin-d6 as an internal standard. Deltamethrin was analyzed by liquid chromatography/tandem mass spectrometry using deltamethrin-phenoxy-(13)C6 as an internal standard. Similar degradation rates of bifenthrin and for related isomeric compounds (e.g., cyfluthrin and β-cyfluthrin) were generally measured in both mixtures for each sediment. First-order half-lives under aerobic conditions ranged from 2.9 to greater than 200 days, with a median value of 18 days. Under anaerobic conditions, the range was from 20 to greater than 200 days, with a median value of 70 days. PMID:23641910

  2. Insight into the mechanism of carbon steel corrosion under aerobic and anaerobic conditions.

    PubMed

    El Mendili, Y; Abdelouas, A; Bardeau, J-F

    2013-06-21

    We particularly focused our study on identifying the corrosion products formed at 30 °C on carbon steel under aerobic and anaerobic conditions and on following their evolution with time due to enhanced microbial activity under environmental and geological conditions. The nature and structural properties of corrosion products were investigated by scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS), X-ray diffraction (XRD) and confocal micro-Raman spectroscopy. Structural characterisation clearly showed the formation of iron oxides (magnetite and maghemite) under aerobic conditions. Under anaerobic conditions, the first corrosion product formed on the steel surface was nanocrystalline mackinawite, which was then followed by a fast transformation process into the pyrrhotite phase, and the Raman spectrum of monoclinic pyrrhotite was proposed for the first time. Finally, this study also shows that in the context of geological disposal of radioactive waste, the corrosion of carbon steel containers in anoxic and sulphidogenic environments sustained by sulphate-reducing bacteria may not be a problem notably due to the formation of a passive layer on the steel surface. PMID:23652337

  3. Aerobic training stimulates growth and promotes disease resistance in Atlantic salmon (Salmo salar).

    PubMed

    Castro, Vicente; Grisdale-Helland, Barbara; Helland, Ståle J; Kristensen, Torstein; Jørgensen, Sven Martin; Helgerud, Jan; Claireaux, Guy; Farrell, Anthony P; Krasnov, Aleksei; Takle, Harald

    2011-10-01

    Improving fish robustness is of utmost relevance to reducing fish losses in farming. Although not previously examined, we hypothesized that aerobic training, as shown for human studies, could strengthen disease resistance in Atlantic salmon (Salmo salar). Thus, we exercised salmon pre-smolts for 6 weeks at two different aerobic training regimes; a continuous intensity training (CT; 0.8bls(-1)) and an interval training (IT; 0.8bl s(-1) 16h and 1.0bl s(-1) 8h) and compared them with untrained controls (C; 0.05bl s(-1)). The effects of endurance training on disease resistance were evaluated using an IPN virus challenge test, while the cardiac immune modulatory effects were characterized by qPCR and microarray gene expression analyses. In addition, swimming performance and growth parameters were investigated. Survival after the IPN challenge was higher for IT (74%) fish than for either CT (64%) or C (61%) fish. While both CT and IT groups showed lower cardiac transcription levels of TNF-α, IL-1β and IL-6 prior to the IPN challenge test, IT fish showed the strongest regulation of genes involved in immune responses and other processes known to affect disease resistance. Both CT and IT regimes resulted in better growth compared with control fish, with CT fish developing a better swimming efficiency during training. Overall, interval aerobic training improved growth and increased robustness of Atlantic salmon, manifested by better disease resistance, which we found was associated with a modulation of relevant gene classes on the cardiac transcriptome. PMID:21726657

  4. Deficient activation by a human cell strain leads to mitomycin resistance under aerobic but not hypoxic conditions.

    PubMed

    Marshall, R S; Paterson, M C; Rauth, A M

    1989-03-01

    Two non-transformed human skin fibroblast strains, GM38 and 3437T, were found to be more sensitive to the bioreductive alkylating agents mitomycin C (MMC) and porfiromycin (PM) under hypoxic compared to aerobic conditions. One of these strains, 3437T, was 6-7 times more resistant to these agents under aerobic exposure conditions, but was identical in sensitivity to the normal strain, GM38, under hypoxic conditions. Aerobic 3437T cells demonstrated no increased resistance to cisplatin compared to the normal strain, arguing against enhanced ability to repair DNA interstrand cross-links as the underlying explanation for the mitomycin resistance. The aerobic resistance of 3437T was not altered by dicumarol, an inhibitor of the enzyme DT-diaphorase which is believed to be involved in aerobic activation of MMC and PM. Dicumarol did increase the resistance of GM38, but not to the same level of resistance demonstrated by 3437T. These results suggest that the aerobic MMC and PM resistance of 3437T may arise, in part, from a deficiency in DT-diaphorase activity. The identical sensitivities under hypoxic conditions indicate that drug activation pathways operative in the absence of oxygen are similar in both the normal and 3437T cells. PMID:2467684

  5. Deficient activation by a human cell strain leads to mitomycin resistance under aerobic but not hypoxic conditions.

    PubMed Central

    Marshall, R. S.; Paterson, M. C.; Rauth, A. M.

    1989-01-01

    Two non-transformed human skin fibroblast strains, GM38 and 3437T, were found to be more sensitive to the bioreductive alkylating agents mitomycin C (MMC) and porfiromycin (PM) under hypoxic compared to aerobic conditions. One of these strains, 3437T, was 6-7 times more resistant to these agents under aerobic exposure conditions, but was identical in sensitivity to the normal strain, GM38, under hypoxic conditions. Aerobic 3437T cells demonstrated no increased resistance to cisplatin compared to the normal strain, arguing against enhanced ability to repair DNA interstrand cross-links as the underlying explanation for the mitomycin resistance. The aerobic resistance of 3437T was not altered by dicumarol, an inhibitor of the enzyme DT-diaphorase which is believed to be involved in aerobic activation of MMC and PM. Dicumarol did increase the resistance of GM38, but not to the same level of resistance demonstrated by 3437T. These results suggest that the aerobic MMC and PM resistance of 3437T may arise, in part, from a deficiency in DT-diaphorase activity. The identical sensitivities under hypoxic conditions indicate that drug activation pathways operative in the absence of oxygen are similar in both the normal and 3437T cells. PMID:2467684

  6. Antibacterial Action of Nitric Oxide-Releasing Chitosan Oligosaccharides against Pseudomonas aeruginosa under Aerobic and Anaerobic Conditions

    PubMed Central

    Reighard, Katelyn P.

    2015-01-01

    Chitosan oligosaccharides were modified with N-diazeniumdiolates to yield biocompatible nitric oxide (NO) donor scaffolds. The minimum bactericidal concentrations and MICs of the NO donors against Pseudomonas aeruginosa were compared under aerobic and anaerobic conditions. Differential antibacterial activities were primarily the result of NO scavenging by oxygen under aerobic environments and not changes in bacterial physiology. Bacterial killing was also tested against nonmucoid and mucoid biofilms and compared to that of tobramycin. Smaller NO payloads were required to eradicate P. aeruginosa biofilms under anaerobic versus aerobic conditions. Under oxygen-free environments, the NO treatment was 10-fold more effective at killing biofilms than tobramycin. These results demonstrate the potential utility of NO-releasing chitosan oligosaccharides under both aerobic and anaerobic environments. PMID:26239983

  7. Iron plaque formed under aerobic conditions efficiently immobilizes arsenic in Lupinus albus L roots.

    PubMed

    Fresno, Teresa; Peñalosa, Jesús M; Santner, Jakob; Puschenreiter, Markus; Prohaska, Thomas; Moreno-Jiménez, Eduardo

    2016-09-01

    Arsenic is a non-threshold carcinogenic metalloid. Thus, human exposure should be minimised, e.g. by chemically stabilizing As in soil. Since iron is a potential As immobiliser, it was investigated whether root iron plaque, formed under aerobic conditions, affects As uptake, metabolism and distribution in Lupinus albus plants. White lupin plants were cultivated in a continuously aerated hydroponic culture containing Fe/EDDHA or FeSO4 and exposed to arsenate (5 or 20 μM). Only FeSO4 induced surficial iron plaque in roots. LA-ICP-MS analysis accomplished on root sections corroborated the association of As to this surficial Fe. Additionally, As(V) was the predominant species in FeSO4-treated roots, suggesting less efficient As uptake in the presence of iron plaque. Fe/EDDHA-exposed roots neither showed such surficial FeAs co-localisation nor As(V) accumulation; in contrast As(III) was the predominant species in root tissue. Furthermore, FeSO4-treated plants showed reduced shoot-to-root As ratios, which were >10-fold lower compared to Fe/EDDHA treatment. Our results highlight the role of an iron plaque formed in roots of white lupin under aerobic conditions on As immobilisation. These findings, to our knowledge, have not been addressed before for this plant and have potential implications on soil remediation (phytostabilisation) and food security (minimising As in crops). PMID:27263113

  8. Growth characteristics of freeze-tolerant baker's yeast Saccharomyces cerevisiae AFY in aerobic batch culture.

    PubMed

    Ji, Meng; Miao, Yelian; Chen, Jie Yu; You, Yebing; Liu, Feilong; Xu, Lin

    2016-01-01

    Saccharomyces cerevisiae AFY is a novel baker's yeast strain with strong freeze-tolerance, and can be used for frozen-dough processing. The present study armed to clarify the growth characteristics of the yeast AFY. Aerobic batch culture experiments of yeast AFY were carried out using media with various initial glucose concentrations, and the culture process was analyzed kinetically. The growth of the yeast AFY exhibited a diauxic pattern with the first growth stage consuming glucose and the second growth stage consuming ethanol. The cell yield decreased with increasing initial glucose concentration in the first growth stage, and also decreased with increasing initial ethanol concentration in the second growth stage. In the initial glucose concentration range of 5.0-40.0 g/L, the simultaneous equations of Monod equation, Luedeking-Piret equation and pseudo-Luedeking-Piret equation could be used to describe the concentrations of cell, ethanol and glucose in either of the two exponential growth phases. At the initial glucose concentrations of 5.0, 10.0 and 40.0 g/L, the first exponential growth phase had a maximal specific cell growth rate of 0.52, 0.98 and 0.99 h(-1), while the second exponential growth phase had a maximal specific cell growth rate of 0.11, 0.06 and 0.07 h(-1), respectively. It was indicated that the efficiency of the yeast production could be improved by reducing the ethanol production in the first growth stage. PMID:27186467

  9. Correlation of growth of aerobic blood cultures in hypertonic broth with antibiotic therapy.

    PubMed Central

    Eng, J; Maeland, A

    1982-01-01

    The aim of this study was to elucidate the mechanisms by which sucrose improves growth in a hypertonic medium for isolating aerobes from blood. Clinical blood cultures were made routinely in duplicate in plain broth consisting of brain heart infusion broth with sodium polyanetholesulfonate, gelatin, and penicillinase and the same broth with 20% sucrose added. The growth patterns of Staphylococcus aureus and Enterobacteriaceae from plain and from hypertonic broth were correlated with the presence or absence of antimicrobial therapy in patients when the blood cultures were collected. In S. aureus bacteremias, 58.7% of the positive cultures collected during treatment of patients with beta-lactam antibiotics showed earlier growth or growth only in hypertonic broth, compared with 16.7% of the cultures taken during treatment with other antimicrobial agents (P less than 0.05) and 17.6% of the cultures made in antibiotic-free intervals (P less than 0.01). In the group of cultures yielding growth of Enterobacteriaceae, growth occurred earlier or solely in hypertonic broth in 28.9% of the cultures taken during treatment with beta-lactam antibiotics, compared with 15.7% of the cultures taken during treatment with other antimicrobial agents and 21.6% of the cultures collected in antibiotic-free intervals (differences not statistically significant). It is concluded that treatment with beta-lactam antibiotics is an important reason for the improved growth of S. aureus from hypertonic broth, but other factors are also involved. PMID:7153339

  10. Aerobic growth of Anoxybacillus pushchinoensis K1(T): emended descriptions of A. pushchinoensis and the genus Anoxybacillus

    NASA Technical Reports Server (NTRS)

    Pikuta, Elena; Cleland, David; Tang, Jane

    2003-01-01

    In this work, corrections are made to the descriptions of the species Anoxybacillus pushchinoensis corrig. and the genus ANOXYBACILLUS: Experiments to determine the relationship of A. pushchinoensis K1(T) to oxygen showed that it was capable of aerobic growth, but preferred to grow anaerobically. During aerobic growth, the redox indicator resazurin was reduced as a result of hydrogen gas production. The facultatively anaerobic nature of K1(T) was ascertained by cultivation in aerobic liquid medium, where growth began at the bottom of the tube. The anaerobic nature of K1(T) was also indicated by a negative catalase reaction. This work is submitted to correct the description of the species A. pushchinoensis from obligate anaerobe to aerotolerant anaerobe and to emend the description of the genus Anoxybacillus from obligate anaerobes or facultative anaerobes to aerotolerant anaerobes or facultative anaerobes.

  11. Requirement of ArcA for redox regulation in Escherichia coli under microaerobic but not anaerobic or aerobic conditions.

    PubMed

    Alexeeva, Svetlana; Hellingwerf, Klaas J; Teixeira de Mattos, M Joost

    2003-01-01

    In Escherichia coli, the two-component regulatory ArcAB system functions as a major control system for the regulation of expression of genes encoding enzymes involved in both aerobic and anaerobic catabolic pathways. Previously, we have described the physiological response of wild-type E. coli to changes in oxygen availability through the complete range from anaerobiosis to full aerobiosis (S. Alexeeva, B. de Kort, G. Sawers, K. J. Hellingwerf, and M. J. Teixeira de Mattos, J. Bacteriol. 182:4934-4940, 2000, and S. Alexeeva, K. J. Hellingwerf, and M. J. Teixeira de Mattos, J. Bacteriol. 184:1402-1406, 2002). Here, we address the question of the contribution of the ArcAB-dependent transcriptional regulation to this response. Wild-type E. coli and a mutant lacking the ArcA regulator were grown in glucose-limited chemostat cultures at controlled levels of oxygen availability ranging from full aerobiosis to complete anaerobiosis. A flux analysis of the distribution of catabolic fluxes over parallel pathways was carried out, and the intracellular redox state (as reflected by the NADH/NAD ratio) was monitored for all steady states. Deletion of ArcA neither significantly altered the in vivo activity of the pyruvate dehydrogenase complex and pyruvate formate lyase nor significantly affected catabolism under fully aerobic and fully anaerobic conditions. In contrast, profound effects of the absence of ArcA were seen under conditions of oxygen-restricted growth: increased respiration, an altered electron flux distribution over the cytochrome o- and d-terminal oxidases, and a significant change in the intracellular redox state were observed. Thus, the ArcA regulator was found to exert major control on flux distribution, and it is concluded that the ArcAB system should be considered a microaerobic redox regulator. PMID:12486057

  12. Biodegradation of Free Phytol by Bacterial Communities Isolated from Marine Sediments under Aerobic and Denitrifying Conditions

    PubMed Central

    Rontani, Jean-François; Bonin, Patricia C.; Volkman, John K.

    1999-01-01

    Biodegradation of (E)-phytol [3,7,11,15-tetramethylhexadec-2(E)-en-1-ol] by two bacterial communities isolated from recent marine sediments under aerobic and denitrifying conditions was studied at 20°C. This isoprenoid alcohol is metabolized efficiently by these two bacterial communities via 6,10,14-trimethylpentadecan-2-one and (E)-phytenic acid. The first step in both aerobic and anaerobic bacterial degradation of (E)-phytol involves the transient production of (E)-phytenal, which in turn can be abiotically converted to 6,10,14-trimethylpentadecan-2-one. Most of the isoprenoid metabolites identified in vitro could be detected in a fresh sediment core collected at the same site as the sediments used for the incubations. Since (E)-phytenal is less sensitive to abiotic degradation at the temperature of the sediments (15°C), the major part of (E)-phytol appeared to be biodegraded in situ via (E)-phytenic acid. (Z)- and (E)-phytenic acids are present in particularly large quantities in the upper section of the core, and their concentrations quickly decrease with depth in the core. This degradation (which takes place without significant production of phytanic acid) is attributed to the involvement of alternating β-decarboxymethylation and β-oxidation reaction sequences induced by denitrifiers. Despite the low nitrate concentration of marine sediments, denitrifying bacteria seem to play a significant role in the mineralization of (E)-phytol. PMID:10584007

  13. Aerobic moving bed biofilm reactor treating thermomechanical pulping whitewater under thermophilic conditions.

    PubMed

    Jahren, Sigrun J; Rintala, Jukka A; Odegaard, Hallvard

    2002-02-01

    The continuously operated laboratory scale Kaldnes moving bed biofilm reactor (MBBR) was used for thermophilic (55 degrees C) aerobic treatment of TMP whitewater. In the MBBR, the biomass is grown on carrier elements that move along with the water in the reactor. Inoculation with mesophilic activated sludge gave 60-65% SCOD removal from the first day onwards. During the 107 days of experiment, the 60-65% SCOD removals were achieved at organic loading rates of 2.5-3.5 kg SCODm(-3) d(-1), the highest loading rates applied during the run and HRT of 13-22h. Carbohydrates, which contributed to 50-60% of the influent SCOD. were removed by 90-95%, while less than 15% of the lignin-like material (30-35% of SCODin) was removed. The sludge yield was 0.23g VSSg SCOD(-1)removed. The results show that the aerobic biofilm process can be successfully operated under thermophilic conditions. PMID:11848344

  14. Effects of environmental conditions on aerobic degradation of a commercial naphthenic acid.

    PubMed

    Kinley, Ciera M; Gaspari, Daniel P; McQueen, Andrew D; Rodgers, John H; Castle, James W; Friesen, Vanessa; Haakensen, Monique

    2016-10-01

    Naphthenic acids (NAs) are problematic constituents in energy-derived waters, and aerobic degradation may provide a strategy for mitigating risks to aquatic organisms. The overall objective of this study was to determine the influence of concentrations of N (as ammonia) and P (as phosphate), and DO, as well as pH and temperatures on degradation of a commercial NA in bench-scale reactors. Commercial NAs provided replicable compounds necessary to compare influences of environmental conditions on degradation. NAs were quantified using high performance liquid chromatography. Microbial diversity and relative abundance were measured in treatments as explanatory parameters for potential effects of environmental conditions on microbial populations to support analytically measured NA degradation. Environmental conditions that positively influenced degradation rates of Fluka NAs included nutrients (C:N 10:1-500:1, C:P 100:1-5000:1), DO (4.76-8.43 mg L(-1)), pH (6-8), and temperature (5-25 °C). Approximately 50% removal of 61 ± 8 mg L(-1) was achieved in less than 2 d after NA introduction, achieving the method detection limit (5 mg L(-1)) by day 6 of the experiment in treatments with a C:N:P ratio of 100:10:1, DO > 8 mg L(-1), pH ∼8-9, and temperatures >23 °C. Microbial diversity was lowest in lower temperature treatments (6-16 °C), which may have resulted in observed slower NA degradation. Based on results from this study, when macro- and micronutrients were available, DO, pH, and temperature (within environmentally relevant ranges) influenced rates of aerobic degradation of Fluka NAs. This study could serve as a model for systematically evaluating environmental factors that influence NA degradation in field scenarios. PMID:27459161

  15. Silicification-induced cell aggregation for the sustainable production of H2 under aerobic conditions.

    PubMed

    Xiong, Wei; Zhao, Xiaohong; Zhu, Genxing; Shao, Changyu; Li, Yaling; Ma, Weimin; Xu, Xurong; Tang, Ruikang

    2015-10-01

    Photobiological hydrogen production is of great importance because of its promise for generating clean renewable energy. In nature, green algae cannot produce hydrogen as a result of the extreme sensitivity of hydrogenase to oxygen. However, we find that silicification-induced green algae aggregates can achieve sustainable photobiological hydrogen production even under natural aerobic conditions. The core-shell structure of the green algae aggregates creates a balance between photosynthetic electron generation and hydrogenase activity, thus allowing the production of hydrogen. This finding provides a viable pathway for the solar-driven splitting of water into hydrogen and oxygen to develop green energy alternatives by using rationally designed cell-material complexes. PMID:26302695

  16. Biodegradation of phenols in a sandstone aquifer under aerobic conditions and mixed nitrate and iron reducing conditions

    NASA Astrophysics Data System (ADS)

    Broholm, Mette M.; Arvin, Erik

    2000-08-01

    Ammonia liquor with very high concentrations of phenol and alkylated phenols is known to have leaked into the subsurface at a former coal carbonization plant in the UK, giving high concentrations of ammonium in the groundwater. In spite of this, no significant concentrations of phenols were found in the groundwater. The potential for biodegradation of the phenols in the sandstone aquifer at the site has been investigated in laboratory microcosms under aerobic (oxygen amended) and mixed nitrate and iron reducing (nitrate enriched and unamended) anaerobic conditions, at a range of concentrations (low: ˜5 mg l -1, high: ˜60 mg l -1, and very high: ˜600 mg l -1) and in the presence of other organic coal-tar compounds (mono- and polyaromatic hydrocarbons (BTEXs and PAHs) and heterocyclic compounds (NSOs)) and ammonia liquor. Sandstone cores and groundwater for the microcosms were collected from within the anaerobic ammonium plume at the field site. Fast and complete degradation of phenol, o- and p-cresol, 2,5- and 3,4-xylenol with no or very short initial lag-phases was observed under aerobic conditions at low concentrations. 2,6- and 3,5-Xylenol were degraded more slowly and 3,5-xylenol degradation was only just complete after about 1 year. The maximum rates of total phenols degradation in duplicate aerobic microcosms were 1.06 and 1.76 mg l -1 day -1. The degradation of phenols in nitrate enriched and unamended anaerobic microcosms was similar. Fast and complete biodegradation of phenol, cresols, 3,4-xylenol and 3,5-xylenol was observed after short lag-phases in the anaerobic microcosms. 2,5-xylenol was partially degraded after a longer lag-phase and 2,6-xylenol persisted throughout the 3 month long experiments. The maximum rates of total phenols degradation in duplicate nitrate enriched and unamended anaerobic microcosms were 0.30-0.38 and 0.29-0.31 mg l -1 day -1, respectively. The highest phenols concentrations in the anaerobic microcosms apparently required

  17. Influence of Partial Denitrification and Mixotrophic Growth of NOB on Microbial Distribution in Aerobic Granular Sludge.

    PubMed

    Winkler, Mari-K H; Le, Quan H; Volcke, Eveline I P

    2015-09-15

    In aerobic granular sludge (AGS), the growth of nitrite oxidizing bacteria (NOB) can be uncoupled from the nitrite supply of ammonia oxidizing bacteria (AOB). Besides, unlike for conventional activated sludge, Nitrobacter was found to be the dominant NOB and not Nitrospira. To explain these experimental observations, two possible pathways have been put forward in literature. The first one involves the availability of additional nitrite from partial denitrification (nitrite-loop) and the second one consists of mixotrophic growth of Nitrobacter in the presence of acetate (ping-pong). In this contribution, mathematical models were set up to assess the possibility of these pathways to explain the reported observations. Simulation results revealed that both pathways influenced the nitrifier distribution in the granules. The nitrite-loop pathway led to an elevated NOB/AOB ratio, while mixotrophic growth of Nitrobacter guaranteed their predominance among the NOB population. Besides, mixotrophic growth of Nitrobacter could lead to NO emission from AGS. An increasing temperature and/or a decreasing oxygen concentration led to an elevated NOB/AOB ratio and increased NO emissions. PMID:26248168

  18. Determination of growth value thresholds for BACTEC PLUS aerobic blood culture vials.

    PubMed

    McGowan, J E; Metchock, B G

    1992-04-01

    Growth value thresholds used to identify positive blood culture vials can be defined by users for each BACTEC NR-660 bacteremia detection instrument. Growth values were compared with the recovery of organisms from vials flagged as positive during the testing of 3.056 high-volume vials containing aerobic (BACTEC PLUS 26) medium over a 2-month period. Results showed that optimal threshold values for our use of these vials varied from those recommended by the manufacturer; if the thresholds defined from these data had been used during the study period, total vials flagged as positive from which no organisms were recovered (false alarms) would have been reduced from 181 (5.9/100 vials tested) to 71 (2.3/100 vials tested), with a minimal decrease in the identification of vials containing usual or occasional pathogens (hits). Adjustments of growth value thresholds by the individual user can make the use of BACTEC instruments more efficient by decreasing further processing of vials from which no organisms are recovered. PMID:1572964

  19. Effect of particulate organic substrate on aerobic granulation and operating conditions of sequencing batch reactors.

    PubMed

    Wagner, Jamile; Weissbrodt, David Gregory; Manguin, Vincent; da Costa, Rejane Helena Ribeiro; Morgenroth, Eberhard; Derlon, Nicolas

    2015-11-15

    The formation and application of aerobic granules for the treatment of real wastewaters still remains challenging. The high fraction of particulate organic matter (XS) present in real wastewaters can affect the granulation process. The present study aims at understanding to what extent the presence of XS affects the granule formation and the quality of the treated effluent. A second objective was to evaluate how the operating conditions of an aerobic granular sludge (AGS) reactor must be adapted to overcome the effects of the presence of XS. Two reactors fed with synthetic wastewaters were operated in absence (R1) or presence (R2) of starch as proxy for XS. Different operating conditions were evaluated. Our results indicated that the presence of XS in the wastewater reduces the kinetic of granule formation. After 52 d of operation, the fraction of granules reached only 21% in R2, while in R1 this fraction was of 54%. The granules grown in presence of XS had irregular and filamentous outgrowths in the surface, which affected the settleability of the biomass and therefore the quality of the effluent. An extension of the anaerobic phase in R2 led to the formation of more compact granules with a better settling ability. A high fraction of granules was obtained in both reactors after an increase of the selection pressure for fast-settling biomass, but the quality of the effluent remained low. Operating the reactors in a simultaneous fill-and-draw mode at a low selection pressure for fast-settling biomass showed to be beneficial for substrate removal efficiency and for suppressing filamentous overgrowth. Average removal efficiencies for total COD, soluble COD, ammonium, and phosphate were 87 ± 4%, 95 ± 1%, 92 ± 10%, and 87 ± 12% for R1, and 72 ± 12%, 86 ± 5%, 71 ± 12%, and 77 ± 11% for R2, respectively. Overall our study demonstrates that the operating conditions of AGS reactors must be adapted according to the wastewater composition. When treating effluents that

  20. Cr(VI) reduction under aerobic and denitrifying conditions by an aquifer-derived Pseudomonad

    NASA Astrophysics Data System (ADS)

    Beller, H. R.; Han, R.; Geller, J. T.

    2009-12-01

    Chromium contamination of groundwater is widespread within the Department of Energy (DOE) complex. For example, at DOE’s Hanford 100 Area in Washington state, the volume of Cr-contaminated groundwater is estimated to be 1.5 billion gallons. Bioremediation (in situ reductive immobilization) studies involving injection of a lactate-containing polymer have been conducted in the Hanford 100H area, where we have observed sequential use of the dissolved electron acceptors present in groundwater, namely, oxygen, nitrate, and sulfate. As part of an effort to explore Cr(VI) reduction under relevant electron-accepting conditions and with relevant bacteria, we have conducted studies with strain RCH2, a denitrifying bacterium similar to Pseudomonas stutzeri that was isolated from the Hanford 100H aquifer. Cell suspension studies with lactate demonstrated that Cr(VI) reduction could occur under either denitrifying or aerobic conditions (at comparable rates), and that reduction was much more rapid when the terminal electron acceptor (i.e., nitrate or O2) was present. It appears that, under both aerobic and denitrifying conditions, the chromate reductase gene(s) are not inducible by Cr; this conclusion is based on the fact that these cell suspension studies were conducted with cells grown in the absence of Cr and resuspended in a buffer that included chloramphenicol, which inhibits protein synthesis. As our studies indicate that anaerobic Cr(VI) reduction by strain RCH2 is much more rapid in the presence of nitrate (i.e., during denitrification) than in its absence, we explored molecular methods that could readily assess in situ denitrification. Specifically, we investigated whether the gene and transcript copy number of diagnostic denitrification genes (nirS and narG) in groundwater could be used to estimate in situ denitrification rates. Continuous culture (chemostat) studies showed strong correlations (r2 values > 0.93) between denitrification rate and either nirS or nar

  1. Growth Conditions and Rifampin Susceptibility

    PubMed Central

    Koch, Arthur L.; Gross, Gayle H.

    1979-01-01

    The susceptibility of Escherichia coli to rifampin was measured during unlimited growth in rich and poor media and during chemostat growth limited by the carbon source. During batch growth at low turbidities, the susceptibility of the bacteria increased as the growth rate decreased, consistent with the longer time available for drug penetration in the poorer media. During chemostat culture, the bacteria remained highly susceptible or became genetically resistant, dependent on the manner in which the bacteria were exposed to the antibiotic. If the concentration of rifampin was abruptly raised, susceptible cells were replaced by genetically resistant cells. However, if the concentration of antibiotic was raised slowly, the genetically susceptible cells continued to grow. This difference in response of chemostat cultures according to mode of drug administration was attributed to an inducible detoxification of the drug by the bacteria, because the susceptible genotype is maintained only when the concentration of rifampin is increased gradually and when a high population of cells is maintained. Direct evidence for the inactivation of the rifampin from the bioassay of culture supernatants is presented. PMID:371543

  2. Plutonium Oxidation State Distribution under Aerobic and Anaerobic Subsurface Conditions for Metal-Reducing Bacteria

    NASA Astrophysics Data System (ADS)

    Reed, D. T.; Swanson, J.; Khaing, H.; Deo, R.; Rittmann, B.

    2009-12-01

    The fate and potential mobility of plutonium in the subsurface is receiving increased attention as the DOE looks to cleanup the many legacy nuclear waste sites and associated subsurface contamination. Plutonium is the near-surface contaminant of concern at several DOE sites and continues to be the contaminant of concern for the permanent disposal of nuclear waste. The mobility of plutonium is highly dependent on its redox distribution at its contamination source and along its potential migration pathways. This redox distribution is often controlled, especially in the near-surface where organic/inorganic contaminants often coexist, by the direct and indirect effects of microbial activity. The redox distribution of plutonium in the presence of facultative metal reducing bacteria (specifically Shewanella and Geobacter species) was established in a concurrent experimental and modeling study under aerobic and anaerobic conditions. Pu(VI), although relatively soluble under oxidizing conditions at near-neutral pH, does not persist under a wide range of the oxic and anoxic conditions investigated in microbiologically active systems. Pu(V) complexes, which exhibit high chemical toxicity towards microorganisms, are relatively stable under oxic conditions but are reduced by metal reducing bacteria under anaerobic conditions. These facultative metal-reducing bacteria led to the rapid reduction of higher valent plutonium to form Pu(III/IV) species depending on nature of the starting plutonium species and chelating agents present in solution. Redox cycling of these lower oxidation states is likely a critical step in the formation of pseudo colloids that may lead to long-range subsurface transport. The CCBATCH biogeochemical model is used to explain the redox mechanisms and final speciation of the plutonium oxidation state distributions observed. These results for microbiologically active systems are interpreted in the context of their importance in defining the overall migration

  3. Electrolysis of trichloromethylated organic compounds under aerobic conditions catalyzed by the B12 model complex for ester and amide formation.

    PubMed

    Shimakoshi, Hisashi; Luo, Zhongli; Inaba, Takuya; Hisaeda, Yoshio

    2016-06-21

    The electrolysis of benzotrichloride at -0.9 V vs. Ag/AgCl in the presence of the B12 model complex, heptamethyl cobyrinate perchlorate, in ethanol under aerobic conditions using an undivided cell equipped with a platinum mesh cathode and a zinc plate anode produced ethylbenzoate in 56% yield with 92% selectivity. The corresponding esters were obtained when the electrolysis was carried out in various alcohols such as methanol, n-propanol, and i-propanol. Benzoyl chloride was detected by GC-MS during the electrolysis as an intermediate for the ester formation. When the electrolysis was carried out under anaerobic conditions, partially dechlorinated products, 1,1,2,2-tetrachloro-1,2-diphenylethane and 1,2-dichlorostilibenes (E and Z forms), were obtained instead of an ester. ESR spin-trapping experiments using 5,5,-dimethylpyrroline N-oxide (DMPO) revealed that the corresponding oxygen-centered radical and carbon-centered radical were steadily generated during the electrolyses under aerobic and anaerobic conditions, respectively. Applications of the aerobic electrolysis to various organic halides, such as substituted benzotrichlorides, are described. Furthermore, the formation of amides with moderate yields by the aerobic electrolysis of benzotrichloride catalyzed by the B12 model complex in the presence of amines in acetonitrile is reported. PMID:27071703

  4. Growth of Aerobic Ripening Bacteria at the Cheese Surface Is Limited by the Availability of Iron

    PubMed Central

    Back, Alexandre; Irlinger, Françoise

    2012-01-01

    The microflora on the surface of smear-ripened cheeses is composed of various species of bacteria and yeasts that contribute to the production of the desired organoleptic properties. The objective of the present study was to show that iron availability is a limiting factor in the growth of typical aerobic ripening bacteria in cheese. For that purpose, we investigated the effect of iron or siderophore addition in model cheeses that were coinoculated with a yeast and a ripening bacterium. Both iron and the siderophore desferrioxamine B stimulated the growth of ripening bacteria belonging to the genera Arthrobacter, Corynebacterium, and Brevibacterium. The extent of stimulation was strain dependent, and generally, the effect of desferrioxamine B was greater than that of iron. Measurements of the expression of genes related to the metabolism of iron by Arthrobacter arilaitensis Re117 by real-time reverse transcription-PCR showed that these genes were transcribed during growth in cheese. The addition of desferrioxamine B increased the expression of two genes encoding iron-siderophore ABC transport binding proteins. The addition of iron decreased the expression of siderophore biosynthesis genes and of part of the genes encoding iron-siderophore ABC transport components. It was concluded that iron availability is a limiting factor in the growth of typical cheese surface bacteria. The selection of strains with efficient iron acquisition systems may be useful for the development of defined-strain surface cultures. Furthermore, the importance of iron metabolism in the microbial ecology of cheeses should be investigated since it may result in positive or negative microbial interactions. PMID:22367081

  5. Combined anaerobic-aerobic treatment of landfill leachates under mesophilic, submesophilic and psychrophilic conditions.

    PubMed

    Kalyuzhnyi, S; Gladchenko, M; Epov, A

    2003-01-01

    As a first step of treatment of landfill leachates (total COD--1,430-3,810 mg/l, total nitrogen 90-162 mg/l), a performance of laboratory UASB reactors has been investigated under mesophilic (30 degrees C), sub-mesophilic (20 degrees C) and psychrophilic (10 degrees C) conditions. Under hydraulic retention times (HRT) of around 7 h, when the average organic loading rates (OLR) were around 5 g COD/l/day, the total COD removal accounted for 81% (on the average) with the effluent concentrations close to anaerobic biodegradability limit (0.25 g COD/l) for mesophilic and sub-mesophilic regimes. The psychrophilic treatment conducted under the average HRT of 8 h and the average OLR of 4.22 g COD/l/day showed a total COD removal of 47% producing the effluents (0.75 g COD/l) more suitable for subsequent biological nitrogen removal. All three anaerobic regimes used for leachate treatment were quite efficient for elimination of heavy metals (Fe, Zn, Cu, Pb, Cd) by concomitant precipitation in the form of insoluble sulphides inside the sludge bed. The application of aerobic/anoxic biofilter as a sole polishing step for psychrophilic anaerobic effluents was acceptable for elimination of biodegradable COD and nitrogen approaching the current standards for direct discharge of treated wastewater. PMID:14640233

  6. Efficient production and secretion of pyruvate from Halomonas sp. KM-1 under aerobic conditions.

    PubMed

    Kawata, Yoshikazu; Nishimura, Taku; Matsushita, Isao; Tsubota, Jun

    2016-03-01

    The alkaliphilic, halophilic bacterium Halomonas sp. KM-1 can utilize both hexose and pentose sugars for the intracellular storage of bioplastic poly-(R)-3-hydroxybutyric acid (PHB) under aerobic conditions. In this study, we investigated the effects of the sodium nitrate concentration on PHB accumulation in the KM-1 strain. Unexpectedly, we observed the secretion of pyruvate, a central intermediate in carbon- and energy-metabolism processes in all organisms; therefore, pyruvate is widely used as a starting material in the industrial biosynthesis of pharmaceuticals and is employed for the production of crop-protection agents, polymers, cosmetics, and food additives. We then further analyzed pyruvate productivity following changes in culture temperature and the buffer concentration. In 48-h batch-cultivation experiments, we found that wild-type Halomonas sp. KM-1 secreted 63.3 g/L pyruvate at a rate of 1.32 g/(L·h), comparable to the results of former studies using mutant and recombinant microorganisms. Thus, these data provided important insights into the production of pyruvate using this novel strain. PMID:26989057

  7. Removal of estrogens in municipal wastewater treatment under aerobic and anaerobic conditions: consequences for plant optimization.

    PubMed

    Joss, Adriano; Andersen, Henrik; Ternes, Thomas; Richle, Philip R; Siegrist, Hansruedi

    2004-06-01

    The removal of estrogens (estrone E1, estradiol E2, and ethinylestradiol EE2) was studied in various municipal wastewater treatment processes equipped for nutrient removal. A biological degradation model is formulated, and kinetic parameters are evaluated with batch experiments under various redox conditions. The resulting model calculations are then compared with sampling campaigns performed on differenttypes of full-scale plant: conventional activated-sludge treatment, a membrane bioreactor, and a fixed-bed reactor. The results show a > 90% removal of all estrogens in the activated sludge processes. (Due to the analytical quantification limit and low influent concentrations, however, this removal efficiency represents only an observable minimum.) The removal efficiencies of 77% and > or = 90% for E1 and E2, respectively, in the fixed-bed reactor represent a good performance in view of the short hydraulic retention time of 35 min. The first-order removal-rate constant in batch experiments observed for E2 varied from 150 to 950 d(-1) for a 1 gSS L(-1) sludge suspension. The removal efficiency of E1 and EE2 clearly depends on the redox conditions, the maximum removal rate occurring under aerobic conditions when E1 was reduced to E2. Sampling campaigns on full-scale plants indicate that the kinetic values identified in batch experiments (without substrate addition) for the natural estrogens may overestimate the actual removal rates. Although this paper does not give direct experimental evidence, it seems that the substrate present in the raw influent competitively inhibits the degradation of E1 and E2. These compounds are therefore removed mainly in activated sludge compartments with low substrate loading. Theoretical evaluation leads us to expect that diffusive mass transfer inside the floc (but not across the laminar boundary layer) appreciably influences the observed degradation rates of E1 and E2, but not of EE2. PMID:15224734

  8. Effects of aerobic exercise on ectopic lipids in patients with growth hormone deficiency before and after growth hormone replacement therapy

    PubMed Central

    Christ, Emanuel R.; Egger, Andrea; Allemann, Sabin; Buehler, Tania; Kreis, Roland; Boesch, Chris

    2016-01-01

    Growth hormone replacement therapy (GHRT) increases exercise capacity and insulin resistance while it decreases fat mass in growth hormone-deficient patients (GHD). Ectopic lipids (intramyocellular (IMCL) and intrahepatocellular lipids (IHCL) are related to insulin resistance. The effect of GHRT on ectopic lipids is unknown. It is hypothesized that exercise-induced utilization of ectopic lipids is significantly decreased in GHD patients and normalized by GHRT. GHD (4 females, 6 males) and age/gender/waist-matched control subjects (CS) were studied. VO2max was assessed on a treadmill and insulin sensitivity determined by a two-step hyperinsulinaemic-euglycaemic clamp. Visceral (VAT) and subcutaneous (SAT) fat were quantified by MR-imaging. IHCL and IMCL were measured before and after a 2 h exercise at 50–60% of VO2max using MR-spectroscopy (∆IMCL, ∆IHCL). Identical investigations were performed after 6 months of GHRT. VO2max was similar in GHD and CS and significantly increased after GHRT; GHRT significantly decreased SAT and VAT. 2 h-exercise resulted in a decrease in IMCL (significant in CS and GHRT) and a significant increase in IHCL in CS and GHD pre and post GHRT. GHRT didn’t significantly impact on ∆IMCL and ∆IHCL. We conclude that aerobic exercise affects ectopic lipids in patients and controls. GHRT increases exercise capacity without influencing ectopic lipids. PMID:26792091

  9. Growth and energy metabolism in aerobic fed-batch cultures of Saccharomyces cerevisiae: Simulation and model verification

    SciTech Connect

    Pham, H.T.B.; Larsson, G.; Enfors, S.O.

    1998-11-20

    Some yeast species are classified as being glucose sensitive, which means that they may produce ethanol also under aerobic conditions when the sugar concentration is high. A kinetic model of overflow metabolism in Saccharomyces cerevisiae was used for simulation of aerobic fed-batch cultivations. An inhibitory effect of ethanol on the maximum respiration of the yeast was observed in the experiments and included in the model. The model predicts respiration, biomass, and ethanol formation and the subsequent ethanol consumption, and was experimentally validated in fed-batch cultivations. Oscillating sugar feed with resulting oscillating carbon dioxide production did not influence the maximum respiration rate, which indicates that the pyruvate dehydrogenase complex is not involved as a bottleneck causing aerobic ethanol formation.

  10. Ethanol production with saccharomyces cerevisiae under aerobic conditions at different potassium concentrations

    SciTech Connect

    Wiimpelmann, M.; Joergensen, B.; Kjaergaard, L.

    1984-04-01

    The specific ethanol productivity with Saccharomyces cerevisiae grown in a chemostat was found to be highly dependent on the ratio of intracellular to extracellular potassium concentration through variations in the energy consumption used for maintenance of the concentration gradient of potassium across the cell membrane. The specific ethanol productivity progressively rose from 0 to 20 mmol h/sup -1/ g/sup -1/ cell dry matter at a growth rate of 0.17 h/sup -1/ when the ratio of intracellular to extracellular potassium concentration was increased from 10 to 80. The ethanol production under potassium limited growth conditions was caused neither by a reduction in the specific respiratory activity nor by variations in the potassium content in cell dry matter. Results which strongly suggest that ethanol production under potassium limited growth conditions is brought about by changes in the ratio of pyruvate oxidase to pyruvate decarboxylase activity through changes in the intracellular pyruvate concentration are presented.

  11. A TatABC-Type Tat Translocase Is Required for Unimpaired Aerobic Growth of Corynebacterium glutamicum ATCC13032

    PubMed Central

    Oertel, Dan; Schmitz, Sabrina; Freudl, Roland

    2015-01-01

    The twin-arginine translocation (Tat) system transports folded proteins across the cytoplasmic membrane of bacteria and the thylakoid membrane of plant chloroplasts. Escherichia coli and other Gram-negative bacteria possess a TatABC-type Tat translocase in which each of the three inner membrane proteins TatA, TatB, and TatC performs a mechanistically distinct function. In contrast, low-GC Gram-positive bacteria, such as Bacillus subtilis, use a TatAC-type minimal Tat translocase in which the TatB function is carried out by a bifunctional TatA. In high-GC Gram-positive Actinobacteria, such as Mycobacterium tuberculosis and Corynebacterium glutamicum, tatA, tatB, and tatC genes can be identified, suggesting that these organisms, just like E. coli, might use TatABC-type Tat translocases as well. However, since contrary to this view a previous study has suggested that C. glutamicum might in fact use a TatAC translocase with TatB only playing a minor role, we reexamined the requirement of TatB for Tat-dependent protein translocation in this microorganism. Under aerobic conditions, the misassembly of the Rieske iron-sulfur protein QcrA was identified as a major reason for the severe growth defect of Tat-defective C. glutamicum mutant strains. Furthermore, our results clearly show that TatB, besides TatA and TatC, is strictly required for unimpaired aerobic growth. In addition, TatB was also found to be essential for the secretion of a heterologous Tat-dependent model protein into the C. glutamicum culture supernatant. Together with our finding that expression of the C. glutamicum TatB in an E. coli ΔtatB mutant strain resulted in the formation of an active Tat translocase, our results clearly indicate that a TatABC translocase is used as the physiologically relevant functional unit for Tat-dependent protein translocation in C. glutamicum and, most likely, also in other TatB-containing Actinobacteria. PMID:25837592

  12. Ecology of the Microbial Community Removing Phosphate from Wastewater under Continuously Aerobic Conditions in a Sequencing Batch Reactor▿

    PubMed Central

    Ahn, Johwan; Schroeder, Sarah; Beer, Michael; McIlroy, Simon; Bayly, Ronald C.; May, John W.; Vasiliadis, George; Seviour, Robert J.

    2007-01-01

    All activated sludge systems for removing phosphate microbiologically are configured so the biomass is cycled continuously through alternating anaerobic and aerobic zones. This paper describes a novel aerobic process capable of decreasing the amount of phosphate from 10 to 12 mg P liter−1 to less than 0.1 mg P liter−1 (when expressed as phosphorus) over an extended period from two wastewaters with low chemical oxygen demand. One wastewater was synthetic, and the other was a clarified effluent from a conventional activated sludge system. Unlike anaerobic/aerobic enhanced biological phosphate removal (EBPR) processes where the organic substrates and the phosphate are supplied simultaneously to the biomass under anaerobic conditions, in this aerobic process, the addition of acetate, which begins the feed stage, is temporally separated from the addition of phosphate, which begins the famine stage. Conditions for establishing this process in a sequencing batch reactor are detailed, together with a description of the changes in poly-β-hydroxyalkanoate (PHA) and poly(P) levels in the biomass occurring under the feed and famine regimes, which closely resemble those reported in anaerobic/aerobic EBPR processes. Profiles obtained with denaturing gradient gel electrophoresis were very similar for communities fed both wastewaters, and once established, these communities remained stable over prolonged periods of time. 16S rRNA-based clone libraries generated from the two communities were also very similar. Fluorescence in situ hybridization (FISH)/microautoradiography and histochemical staining revealed that “Candidatus Accumulibacter phosphatis” bacteria were the dominant poly(P)-accumulating organisms (PAO) in both communities, with the phenotype expected for PAO. FISH also identified large numbers of betaproteobacterial Dechloromonas and alphaproteobacterial tetrad-forming organisms related to Defluviicoccus in both communities, but while these organisms assimilated

  13. Modeling the influence of varying hydraulic conditions on aerobic respiration and denitrification in the hyporheic zone

    NASA Astrophysics Data System (ADS)

    Trauth, N.; Schmidt, C.; Fleckenstein, J. H.

    2013-12-01

    Exchange of water and solutes across the stream-sediment interface is an important control for biogeochemical transformations in the hyporheic zone (HZ) with measurable impacts on nutrient cycling and solute attenuation in fluvial systems. Here we investigate the interplay between turbulent stream flow and HZ flow under various hydraulic conditions applied to two cases: a) three-dimensional generic pool-riffle sequences with different morphological properties, and b) a real mid-stream gravel-bar. Stream flow is simulated by the open source computational fluid dynamics (CFD) software OpenFOAM which provides the hydraulic head distribution at the streambed. It is sequentially coupled to the top of the groundwater model code MIN3P, simulating flow, solute transport, aerobic respiration (AR) and denitrification (DN) in the HZ. Flow in the HZ is directly influenced by the hydraulic head distribution at the streambed surface and the ambient groundwater flow. Three reactive transport scenarios are considered: 1) stream water as the primary source of dissolved oxygen (DO), nitrate (NO3) and dissolved organic carbon (DOC), 2) upwelling groundwater as an additionally source of NO3, and 3) upwelling groundwater as an additional source of DO in various concentrations. Results show an increase in hyporheic exchange flow for increasing stream discharge with a concurrent decrease in residence time. The fraction of circulating stream water through the HZ is in the range of 1x10-5 to 1x10-6 per unit stream length, decreasing with increasing discharge. Ambient groundwater flow in both the up- and downwelling direction diminishes significantly the hyporheic exchange flow and extent. Biogeochemical processes in the HZ are strongly controlled by ambient groundwater flow, even more so than by changes in stream discharge. AR and DN efficiencies of the HZ are significantly reduced by up- and downwelling groundwater and are positively correlated with median residence times. AR occurs in

  14. Activity and growth of anammox biomass on aerobically pre-treated municipal wastewater.

    PubMed

    Laureni, Michele; Weissbrodt, David G; Szivák, Ilona; Robin, Orlane; Nielsen, Jeppe Lund; Morgenroth, Eberhard; Joss, Adriano

    2015-09-01

    Direct treatment of municipal wastewater (MWW) based on anaerobic ammonium oxidizing (anammox) bacteria holds promise to turn the energy balance of wastewater treatment neutral or even positive. Currently, anammox processes are successfully implemented at full scale for the treatment of high-strength wastewaters, whereas the possibility of their mainstream application still needs to be confirmed. In this study, the growth of anammox organisms on aerobically pre-treated municipal wastewater (MWW(pre-treated)), amended with nitrite, was proven in three parallel reactors. The reactors were operated at total N concentrations in the range 5-20 mg(N)∙L(-1), as expected for MWW. Anammox activities up to 465 mg(N)∙L(-1)∙d(-1) were reached at 29 °C, with minimum doubling times of 18 d. Lowering the temperature to 12.5 °C resulted in a marked decrease in activity to 46 mg(N)∙L(-1)∙d(-1) (79 days doubling time), still in a reasonable range for autotrophic nitrogen removal from MWW. During the experiment, the biomass evolved from a suspended growth inoculum to a hybrid system with suspended flocs and wall-attached biofilm. At the same time, MWW(pre-treated) had a direct impact on process performance. Changing the influent from synthetic medium to MWW(pre-treated) resulted in a two-month delay in net anammox growth and a two to three-fold increase in the estimated doubling times of the anammox organisms. Interestingly, anammox remained the primary nitrogen consumption route, and high-throughput 16S rRNA gene-targeted amplicon sequencing analyses revealed that the shift in performance was not associated with a shift in dominant anammox bacteria ("Candidatus Brocadia fulgida"). Furthermore, only limited heterotrophic denitrification was observed in the presence of easily biodegradable organics (acetate, glucose). The observed delays in net anammox growth were thus ascribed to the acclimatization of the initial anammox population or/and the development of a side

  15. Chromium isotopic fractionation during Cr(VI) reduction by Bacillus sp. under aerobic conditions.

    PubMed

    Xu, Fen; Ma, Teng; Zhou, Lian; Hu, Zhifang; Shi, Liu

    2015-07-01

    This study investigated the fractionation of chromium isotopes during chromium reduction by Bacillus sp. under aerobic condition, variable carbon source (glucose) concentration (0, 0.1, 1, 2.5 and 10mM), and incubation temperatures (4, 15, 25 and 37°C). The results revealed that the δ(53)Cr values in the residual Cr(VI) increased with the degree of Cr reduction, and followed a Rayleigh fractionation model. The addition of glucose only slightly affected cell-specific Cr(VI) reduction rates (cSRR). However, the value of ε (2.00±0.21‰) in the experiments with different concentrations of glucose (0.1, 1, 2.5 and 10mM) was smaller than that from the experiment without glucose (3.74±0.16‰). The results indicated that the cell-specific reduction rate is not the sole control on the degree of isotopic fractionation, and different metabolic pathways would result in differing degrees of Cr isotopic fractionation. The cSRR decreased with decreasing temperature, showing that the values of ε were 7.62±0.36‰, 4.59±0.28‰, 3.09±0.16‰ and 1.99±0.23‰ at temperatures of 4, 15, 25 and 37°C, respectively. It shown that increasing cSRR linked to decreasing fractionations has been associated with increasing temperatures. Overall, our results revealed that temperature is a primary factor affecting Cr isotopic fractionation under microbial actions. PMID:25777078

  16. Does the aerobic capacity of fish muscle change with growth rates?

    PubMed

    Pelletier, D; Guderley, H; Dutil, J D

    1993-08-01

    To ascertain whether growth rate modifies the oxidative capacity of fish white muscle, we examined the effects of individual growth rate on the activities of four mitochondrial enzymes in white muscle of the fast growing Atlantic cod,Gadus morhua. Growth rates were individually monitored in cod held at three acclimation temperatures during experiments repeated in four seasons. The size dependence of citrate synthase (CS), cytochrome C oxidase (CCO) and β-hydroxyacyl CoA dehydrogenase (HOAD) activities was established using wild cod ranging from 115 to 17,350 g. Given their negative allometry, CS and CCO activities in the experimental cod were corrected to those expected for a 1.2 kg animal. HOAD activities did not change with size. The specific activities of CCO and CS were positively correlated with growth rate. However, for both enzymes, season explained more of the variability than growth rate or temperature. Season was the only factor to significantly affect the activity of HOAD, while temperature and season interacted to determine glutamate dehydrogenase activity. CS activity was positively correlated with the initial condition of the cod, which differed among the seasons. The other enzymes did not show this relationship. The independent changes of these enzymes suggest that mitochondria undergo qualitative modifications with changes in growth rate, season and size. Although growth rate and the activities of CCO and CS are positively correlated, the activity of the mitochondrial enzymes is more affected by size, physical condition and season. PMID:24202687

  17. A Model of the Cardiorespiratory Response to Aerobic Exercise in Healthy and Heart Failure Conditions.

    PubMed

    Fresiello, Libera; Meyns, Bart; Di Molfetta, Arianna; Ferrari, Gianfranco

    2016-01-01

    The physiological response to physical exercise is now recognized as an important tool which can aid the diagnosis and treatment of cardiovascular diseases. This is due to the fact that several mechanisms are needed to accommodate a higher cardiac output and a higher oxygen delivery to tissues. The aim of the present work is to provide a fully closed loop cardiorespiratory simulator reproducing the main physiological mechanisms which arise during aerobic exercise. The simulator also provides a representation of the impairments of these mechanisms in heart failure condition and their effect on limiting exercise capacity. The simulator consists of a cardiovascular model including the left and right heart, pulmonary and systemic circulations. This latter is split into exercising and non-exercising regions and is controlled by the baroreflex and metabolic mechanisms. In addition, the simulator includes a respiratory model reproducing the gas exchange in lungs and tissues, the ventilation control and the effects of its mechanics on the cardiovascular system. The simulator was tested and compared to the data in the literature at three different workloads whilst cycling (25, 49 and 73 watts). The results show that the simulator is able to reproduce the response to exercise in terms of: heart rate (from 67 to 134 bpm), cardiac output (from 5.3 to 10.2 l/min), leg blood flow (from 0.7 to 3.0 l/min), peripheral resistance (from 0.9 to 0.5 mmHg/(cm(3)/s)), central arteriovenous oxygen difference (from 4.5 to 10.8 ml/dl) and ventilation (6.1-25.5 l/min). The simulator was further adapted to reproduce the main impairments observed in heart failure condition, such as reduced sensitivity of baroreflex and metabolic controls, lower perfusion to the exercising regions (from 0.6 to 1.4 l/min) and hyperventilation (from 9.2 to 40.2 l/min). The simulator we developed is a useful tool for the description of the basic physiological mechanisms operating during exercise. It can reproduce

  18. A Model of the Cardiorespiratory Response to Aerobic Exercise in Healthy and Heart Failure Conditions

    PubMed Central

    Fresiello, Libera; Meyns, Bart; Di Molfetta, Arianna; Ferrari, Gianfranco

    2016-01-01

    The physiological response to physical exercise is now recognized as an important tool which can aid the diagnosis and treatment of cardiovascular diseases. This is due to the fact that several mechanisms are needed to accommodate a higher cardiac output and a higher oxygen delivery to tissues. The aim of the present work is to provide a fully closed loop cardiorespiratory simulator reproducing the main physiological mechanisms which arise during aerobic exercise. The simulator also provides a representation of the impairments of these mechanisms in heart failure condition and their effect on limiting exercise capacity. The simulator consists of a cardiovascular model including the left and right heart, pulmonary and systemic circulations. This latter is split into exercising and non-exercising regions and is controlled by the baroreflex and metabolic mechanisms. In addition, the simulator includes a respiratory model reproducing the gas exchange in lungs and tissues, the ventilation control and the effects of its mechanics on the cardiovascular system. The simulator was tested and compared to the data in the literature at three different workloads whilst cycling (25, 49 and 73 watts). The results show that the simulator is able to reproduce the response to exercise in terms of: heart rate (from 67 to 134 bpm), cardiac output (from 5.3 to 10.2 l/min), leg blood flow (from 0.7 to 3.0 l/min), peripheral resistance (from 0.9 to 0.5 mmHg/(cm3/s)), central arteriovenous oxygen difference (from 4.5 to 10.8 ml/dl) and ventilation (6.1–25.5 l/min). The simulator was further adapted to reproduce the main impairments observed in heart failure condition, such as reduced sensitivity of baroreflex and metabolic controls, lower perfusion to the exercising regions (from 0.6 to 1.4 l/min) and hyperventilation (from 9.2 to 40.2 l/min). The simulator we developed is a useful tool for the description of the basic physiological mechanisms operating during exercise. It can reproduce

  19. BIODEGRADATION KINETICS AND TOXICITY OF VEGETABLE OIL TRIACYLGLYCEROLS UNDER AEROBIC CONDITIONS

    EPA Science Inventory

    The aerobic biodegradation of five triacylglycerols (TAGs), three liquids [triolein (OOO), trilinolein (LLL), and trilinolenin (LnLnLn)] and two solids [tripalmitin (PPP) and tristearin (SSS)] was studied in water. Respirometry tests were designed and conducted to determine the b...

  20. Effects of Aerobic and Microaerobic Conditions on Anaerobic Ammonium-Oxidizing (Anammox) Sludge

    PubMed Central

    Strous, M.; Van Gerven, E.; Kuenen, J. G.; Jetten, M.

    1997-01-01

    The anaerobic ammonium oxidation (Anammox) process is a promising novel option for removing nitrogen from wastewater. In this study it was shown that the Anammox process was inhibited reversibly by the presence of oxygen. Furthermore, aerobic nitrifiers were shown not to play an important role in the Anammox process. PMID:16535633

  1. EFFECTS OF AEROBIC CONDITIONING ON CARDIOVASCULAR SYMPATHETIC RESPONSE TO AND RECOVERY FROM CHALLENGE

    PubMed Central

    Lindgren, M; Alex, C; Shapiro, PA; McKinley, PS; Brondolo, EN; Myers, MM; Choi, CJ; Lopez-Pintado, S; Sloan, RP

    2013-01-01

    Objective Exercise has widely-documented cardioprotective effects but the mechanisms behind these effects are still poorly understood. Here, we test the hypothesis that aerobic training lowers cardiovascular sympathetic responses to and speeds recovery from challenge. Methods We conducted a randomized controlled trial contrasting aerobic versus strength training on indices of cardiac (pre-ejection period, PEP) and vascular (low-frequency blood pressure variability, LF-BPV) sympathetic responses to and recovery from psychological and orthostatic challenge in 149 young, healthy and sedentary adults. Results Aerobic and strength training did not alter PEP or LF-BPV reactivity to or recovery from challenge. Conclusions These findings, from a large randomized controlled trial using an intent-to-treat design, show that moderate aerobic exercise training has no effect on PEP and LF BPV reactivity to or recovery from psychological or orthostatic challenge. In healthy young adults, the cardioprotective effects of exercise training are unlikely to be mediated by changes in sympathetic activity. PMID:23889039

  2. [Research advances in denitrogenation characteristics of aerobic denitrifiers].

    PubMed

    Liang, Shu-Cheng; Zhao, Min; Lu, Lei; Zhao, Li-Yan

    2010-06-01

    The discovery of aerobic denitrifiers is the enrichment and breakthrough of traditional denitrification theory. Owing to their unique superiority in denitrogenation, aerobic denitrifiers have become a hotspot in the study of bio-denitrogenation of waste water. Under aerobic conditions, the aerobic denitrifiers can utilize organic carbon sources for their growth, and produce N2 from nitrate and nitrite. Most of the denitrifiers can also proceed with heterotrophic nitrification simultaneously, transforming NH4(+)-N to gaseous nitrogen. In this paper, the denitrogenation characteristics and action mechanisms of some isolated aerobic denitrifiers were discussed from the aspects of electron theory and denitrifying enzyme system. The effects of the environmental factors DO, carbon sources, and C/N on the denitrogenation process of aerobic denitrifiers were analyzed, and the screening methods as well as the present and potential applications of aerobic denitrifiers in wastewater treatment were described and discussed. PMID:20873638

  3. Evaluation of (/sup 3/H)thymidine uptake method for studying growth of spiroplasmas under various conditions

    SciTech Connect

    Bastian, F.O.; Baliga, B.S.; Pollock, H.M.

    1988-10-01

    (/sup 3/H)thymidine uptake and colony counts are quantitative and inexpensive methods for studying Spiroplasma growth. Using these techniques, we demonstrated subtle effects on the growth of suckling mouse cataract agent of medium alterations, inoculum size, and freezing of cultures. In addition, suckling mouse cataract agent multiplied more actively under aerobic than under anaerobic conditions. These techniques have wide application for the study of Spiroplasma growth and will be useful for the development of a defined medium.

  4. Cu-Catalyzed Consecutive Hydroxylation and Aerobic Oxidative Cycloetherification under Microwave Conditions: Entry to 2-Arylbenzofuran-3-carboxylic Acids.

    PubMed

    Xu, Tianlong; Zhang, Ensheng; Wang, Dejian; Wang, Yan; Zou, Yong

    2015-05-01

    A convenient one-pot synthesis of 2-arylbenzofuran-3-carboxylic acids from (E)-2-(2-bromophenyl)-3-phenylacrylic acids via Cu-catalyzed consecutive hydroxylation and aerobic oxidative cycloetherification under microwave conditions has been developed. This protocol employed the reagent combination of Cu(OAc)2, 1,10-phen, and KOH in DMSO/H2O (1:1), all of which are cost-effective, readily available, and easily removable from the reaction mixture. Utilizing this synthetic protocol, various 2-arylbenzofuran-3-carboxylic acids as well as the natural product moracin M have been synthesized in satisfactory yields under mild conditions. PMID:25836742

  5. Terminal Oxidases of Bacillus subtilis Strain 168: One Quinol Oxidase, Cytochrome aa3 or Cytochrome bd, Is Required for Aerobic Growth

    PubMed Central

    Winstedt, Lena; von Wachenfeldt, Claes

    2000-01-01

    The gram-positive endospore-forming bacterium Bacillus subtilis has, under aerobic conditions, a branched respiratory system comprising one quinol oxidase branch and one cytochrome oxidase branch. The system terminates in one of four alternative terminal oxidases. Cytochrome caa3 is a cytochrome c oxidase, whereas cytochrome bd and cytochrome aa3 are quinol oxidases. A fourth terminal oxidase, YthAB, is a putative quinol oxidase predicted from DNA sequence analysis. None of the terminal oxidases are, by themselves, essential for growth. However, one quinol oxidase (cytochrome aa3 or cytochrome bd) is required for aerobic growth of B. subtilis strain 168. Data indicating that cytochrome aa3 is the major oxidase used by exponentially growing cells in minimal and rich medium are presented. We show that one of the two heme-copper oxidases, cytochrome caa3 or cytochrome aa3, is required for efficient sporulation of B. subtilis strain 168 and that deletion of YthAB in a strain lacking cytochrome aa3 makes the strain sporulation deficient. PMID:11073895

  6. Using a tank flow model with PEARL to measure the variation in pesticide persistence between anaerobic and aerobic soil conditions

    NASA Astrophysics Data System (ADS)

    Real, Joaquin; Seiterle-Winn, Natalie; Frances, Felix

    2013-04-01

    Pesticide leaching is very sensitive to the transformation rate (Boesten and Linden, 1991). The values of the transformation rates of the pesticides differ between aerobic and anaerobic soil conditions. The main objective is to determine if there is a significant variation in pesticide persistence between aerobic and anaerobic soil conditions. An auxiliary hydrological model is used with the PEARL model (Leistra et al, 2001). The auxiliary model determines the degree of saturation of the soil at each time step. The value of the degradation rate for a given pesticide in the PEARL model varies depending on the time periods with saturated or unsaturated soil conditions. The proposed auxiliary model has been conceptualized as a static tank flow model based on the actual evapotranspiration of the crop plants. It is based on the RIBAV model (Garcia-Arias et al. 2012) used for the modeling of riparian vegetation zonation. The tank represents a soil column which also includes the superficial root layer. The lower capacity limit of this tank is the permanent wilting moisture of the soil. The upper capacity limit represents the saturated condition of the soil. The tanks input flows are precipitation and irrigation. In contrast, output flows are the actual evapotranspiration and the discharge of the tank. The most relevant model parameters are the soil retention curves, the crop parameters (specially related to root depths and crop coefficients) and the daily meteorological data (such as precipitation and potential evapotranspiration). The main output of the auxiliary model is the relative soil moisture, which determines if the PEARL model should use the transformation rate value for aerobic or for anaerobic conditions. In order to prove the applicability of the model, it was tested with various pesticides, which cover a wide range of transformation rates. The results show that the auxiliary tank model is able to determine the partition of the pesticides degrading in both

  7. Molecular characterization of a microbial consortium involved in methane oxidation coupled to denitrification under micro-aerobic conditions

    PubMed Central

    Liu, Jingjing; Sun, Faqian; Wang, Liang; Ju, Xi; Wu, Weixiang; Chen, Yingxu

    2014-01-01

    Methane can be used as an alternative carbon source in biological denitrification because it is nontoxic, widely available and relatively inexpensive. A microbial consortium involved in methane oxidation coupled to denitrification (MOD) was enriched with nitrite and nitrate as electron acceptors under micro-aerobic conditions. The 16S rRNA gene combined with pmoA phylogeny of methanotrophs and nirK phylogeny of denitrifiers were analysed to reveal the dominant microbial populations and functional microorganisms. Real-time quantitative polymerase chain reaction results showed high numbers of methanotrophs and denitrifiers in the enriched consortium. The 16S rRNA gene clone library revealed that Methylococcaceae and Methylophilaceae were the dominant populations in the MOD ecosystem. Phylogenetic analyses of pmoA gene clone libraries indicated that all methanotrophs belonged to Methylococcaceae, a type I methanotroph employing the ribulose monophosphate pathway for methane oxidation. Methylotrophic denitrifiers of the Methylophilaceae that can utilize organic intermediates (i.e. formaldehyde, citrate and acetate) released from the methanotrophs played a vital role in aerobic denitrification. This study is the first report to confirm micro-aerobic denitrification and to make phylogenetic and functional assignments for some members of the microbial assemblages involved in MOD. PMID:24245852

  8. Diversity of methanotrophs in Zoige wetland soils under both anaerobic and aerobic conditions.

    PubMed

    Yun, Juanli; Ma, Anzhou; Li, Yaoming; Zhuang, Guoqiang; Wang, Yanfen; Zhang, Hongxun

    2010-01-01

    Zoige wetland is one of the most important methane emission centers in China. The oxidation of methane in the wetland affects global warming, soil ecology and atmospheric chemistry. Despite their global significance, microorganisms that consume methane in Zoige wetland remain poorly characterized. In this study, we investigated methanotrophs diversity in soil samples from both anaerobic site and aerobic site in Zoige wetland using pmoA gene as a molecular marker. The cloning library was constructed according to the pmoA sequences detected. Four clusters of methanotrophs were detected. The phylogenetic tree showed that all four clusters detected were affiliated to type I methanotrophs. Two novel clusters (cluster 1, cluster 2) were found to relate to none of the recognized genera of methanotrophs. These clusters have no cultured representatives and reveal an ecological adaptation of particular uncultured methanotrophs in Zoige wetland. Two clusters were belonging to Methylobacter and Methylococcus separately. Denaturing gradient gel electrophoresis gel bands pattern retrieved from these two samples revealed that the community compositions of anaerobic soil and aerobic soil were different from each other while anaerobic soil showed a higher metanotrophs diversity. Real-time PCR assays of the two samples demonstrated that aerobic soil sample in Zoige wetland was 1.5 times as much copy numbers as anaerobic soil. These data illustrated that methanotrophs are a group of microorganisms influence the methane consumption in Zoige wetland. PMID:21179963

  9. Rural population growth and living conditions.

    PubMed

    Li, N; Zhu, C

    1991-01-01

    The problem of the effect of population growth on subsistence conditions is addressed by developing generalized premises, principles, and methods for quantifying standards or conditions for growth. This method is applied to 1989 data for Nanzheng Country, China. Background information is provided on an experiment made public in 1985 and implemented in 1986 by the Family Planning (FP) Department of Nanzheng County of Shaanxi Province in Hongmiao District in which the following conditions were placed on bearing a second child: 1) income must be 20% higher than the average village income level, and breeders must have an average income of not 400 yuan/year, crop planters not 300 yuan/year, textile weavers not 200 yuan/year, and industrial and subsidiary production workers not 400 yuan/year (generally 4 pigs or 100 chickens or ducks) or 2) 100 income-producing trees must be planted around he residential area/family plot or stony fields must be transformed into arable land under the contract responsibility system, or groves, orchards, or tea plantations must be planted. These conditions must be met one year prior to proposing to have a second child. The approval rate in 1986-88 was 88.7%, and the second parity rate was 78.4%. Deteriorated conditions had not yet occurred in this country when this proposal was made. The premises considered important in preparing assistance conditions were determined. 1) Conditions for population growth should be resolved within the area. 2) Subsistence conditions should be taken care of by the family. 3) There should be a centralized standard, not a family standard, such that living conditions/capita should not decrease because of population growth. Quantification is made expressing the relationship between subsistence and growth. The application of these conditions for households in Hongmiao District is that the average subsistence conditions need to be higher than other households by 12.3% for new population growth. The assumption is

  10. Bacterially Induced Dolomite Formation in the Presence of Sulfate Ions under Aerobic Conditions

    NASA Astrophysics Data System (ADS)

    Sanchez-Roman, M.; McKenzie, J. A.; Vasconcelos, C.; Rivadeneyra, M.

    2005-12-01

    The origin of dolomite remains a long-standing enigma in sedimentary geology because, although thermodynamically favorable, precipitation of dolomite from modern seawater does not occur. Experiments conducted at elevated temperatures (200 oC) indicated that the presence of small concentrations of sulfate ions inhibits the transformation of calcite to dolomite [1]. Indeed, sulfate ions appeared to inhibit dolomite formation above 2 mM concentration (versus 28 mM in modern seawater). Recently, culture experiments have demonstrated that sulfate-reducing bacteria mediate the precipitation of dolomite at Earth surface conditions in the presence of sustained sulfate ion concentrations [2,3]. Additionally, in a number of modern hypersaline environments, dolomite forms from solutions with high sulfate ion concentrations (2 to 70 times seawater). These observations suggest that the experimentally observed sulfate-ion inhibition [1] may not apply to all ancient dolomite formation. Here, we report aerobic culture experiments conducted at low temperatures (25 and 35 oC) and variable sulfate ion concentrations (0, 0.5, 1 and 2 x seawater values) using moderately halophilic bacteria, Halomonas meridiana. After an incubation period of 15 days, experiments at 35 oC with variable sulfate ion concentrations (0, 0.5 x and seawater values) contained crystals of Ca-dolomite and stochiometric dolomite. The experiment at 35 oC with 2 x seawater sulfate ion concentration produced dolomite crystals after 20 days of incubation. In a parallel set of experiments at 25 oC, precipitation of dolomite was observed after 25 days of incubation in cultures with variable sulfate ion concentrations (0, 0.5 x and seawater values). In the culture with 2 x seawater sulfate ion concentration, dolomite crystals were observed after 30 days. Our study demonstrates that halophilic bacteria (or heterotrophic microorganisms), which do not require sulfate ions for metabolism, can mediate dolomite precipitation

  11. Growth dynamics of specific spoilage organisms and associated spoilage biomarkers in chicken breast stored aerobically

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study was performed to identify and quantify selected volatile spoilage biomarkers in a headspace over chicken breast using solid phase microextraction (SPME) combined with gas chromatography-mass spectrometry-flame ionization detectors (GC-MS/FID). The chicken breast samples were aerobically s...

  12. Construction of CoA-dependent 1-butanol synthetic pathway functions under aerobic conditions in Escherichia coli.

    PubMed

    Kataoka, Naoya; Vangnai, Alisa S; Pongtharangkul, Thunyarat; Tajima, Takahisa; Yakushi, Toshiharu; Matsushita, Kazunobu; Kato, Junichi

    2015-06-20

    1-Butanol is an important industrial platform chemical and an advanced biofuel. While various groups have attempted to construct synthetic pathways for 1-butanol production, efforts to construct a pathway that functions under aerobic conditions have met with limited success. Here, we constructed a CoA-dependent 1-butanol synthetic pathway that functions under aerobic conditions in Escherichia coli, by expanding the previously reported (R)-1,3-butanediol synthetic pathway. The pathway consists of phaA (acetyltransferase) and phaB (NADPH-dependent acetoacetyl-CoA reductase) from Ralstonia eutropha, phaJ ((R)-specific enoyl-CoA hydratase) from Aeromonas caviae, ter (trans-enoyl-CoA reductase) from Treponema denticola, bld (butylraldehyde dehydrogenase) from Clostridium saccharoperbutylacetonicum, and inherent alcohol dehydrogenase(s) from E. coli. To evaluate the potential of this pathway for 1-butanol production, culture conditions, including volumetric oxygen transfer coefficient (kLa) and pH were optimized in a mini-jar fermenter. Under optimal conditions, 1-butanol was produced at a concentration of up to 8.60gL(-1) after 46h of fed-batch cultivation. PMID:25865277

  13. Whole-Genome Transcriptional Analysis of Chemolithoautotrophic Thiosulfate Oxidation by Thiobacillus denitrificans Under Aerobic vs. Denitrifying Conditions

    SciTech Connect

    Beller, H R; Letain, T E; Chakicherla, A; Kane, S R; Legler, T C; Coleman, M A

    2006-04-22

    Thiobacillus denitrificans is one of the few known obligate chemolithoautotrophic bacteria capable of energetically coupling thiosulfate oxidation to denitrification as well as aerobic respiration. As very little is known about the differential expression of genes associated with ke chemolithoautotrophic functions (such as sulfur-compound oxidation and CO2 fixation) under aerobic versus denitrifying conditions, we conducted whole-genome, cDNA microarray studies to explore this topic systematically. The microarrays identified 277 genes (approximately ten percent of the genome) as differentially expressed using Robust Multi-array Average statistical analysis and a 2-fold cutoff. Genes upregulated (ca. 6- to 150-fold) under aerobic conditions included a cluster of genes associated with iron acquisition (e.g., siderophore-related genes), a cluster of cytochrome cbb3 oxidase genes, cbbL and cbbS (encoding the large and small subunits of form I ribulose 1,5-bisphosphate carboxylase/oxygenase, or RubisCO), and multiple molecular chaperone genes. Genes upregulated (ca. 4- to 95-fold) under denitrifying conditions included nar, nir, and nor genes (associated respectively with nitrate reductase, nitrite reductase, and nitric oxide reductase, which catalyze successive steps of denitrification), cbbM (encoding form II RubisCO), and genes involved with sulfur-compound oxidation (including two physically separated but highly similar copies of sulfide:quinone oxidoreductase and of dsrC, associated with dissimilatory sulfite reductase). Among genes associated with denitrification, relative expression levels (i.e., degree of upregulation with nitrate) tended to decrease in the order nar > nir > nor > nos. Reverse transcription, quantitative PCR analysis was used to validate these trends.

  14. Growth parameters of escherichia coli O157:H7, salmonella and listeria monocytogenes and aerobic mesophilic bacteria of apple cider amended with nisin-EDTA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effect of nisin (0 or 300 IU), Ethylenediamine Tetraacetic Acid (EDTA, 20 mM) and (nisin 300 IU+ EDTA 20 mM) on growth parameters; including lag period (LP) and growth rate (GR) of Escherichia coli O157:H7, L. monocytogenes and Salmonella spp. in the presence or absence of aerobic mesophilic bac...

  15. Interaction between phosphorus removal and hybrid granular sludge formation under low hydraulic selection pressure at alternating anaerobic/aerobic conditions.

    PubMed

    Lang, Longqi; Wan, Junfeng; Zhang, Jing; Wang, Jie; Wang, Yan

    2015-01-01

    The hybrid granular sludge (HGS) formation and its performances on phosphorus removal were investigated in a sequencing batch airlift reactor. Under conditions of low superficial air velocity (SAV = 0.68 cm s(-1)) and relatively long settling time (15-30 min), aerobic granules appeared and coexisted with bio-flocs after 120 days operation. At the stable phase, 54% of total suspended solid (m/m) was granular sludge with the two typical sizes (D(mean) = 1.77 ± 0.33 and 0.89 ± 0.11 mm) in the reactor, where the settling velocity was 98.7 ± 12.4 and 37.8 ± 0.9 m h(-1) for the big and small granules. With progressive extension of anaerobic time from 15 to 60 min before aerobic condition per cycle during the whole experiment, the HGS system can be maintained at a high total phosphorus removal efficiency (ca. 99%) since Day-270. The phosphorus content (wt %) in biomass was respectively 9.54 ± 0.29, 7.60 ± 0.48 and 6.15 ± 0.59 for the big granules, small granules and flocs. PMID:25921951

  16. The Peroxiredoxin Tpx1 Is Essential as a H2O2 Scavenger during Aerobic Growth in Fission Yeast

    PubMed Central

    Jara, Mónica; Vivancos, Ana P.; Calvo, Isabel A.; Moldón, Alberto; Sansó, Miriam

    2007-01-01

    Peroxiredoxins are known to interact with hydrogen peroxide (H2O2) and to participate in oxidant scavenging, redox signal transduction, and heat-shock responses. The two-cysteine peroxiredoxin Tpx1 of Schizosaccharomyces pombe has been characterized as the H2O2 sensor that transduces the redox signal to the transcription factor Pap1. Here, we show that Tpx1 is essential for aerobic, but not anaerobic, growth. We demonstrate that Tpx1 has an exquisite sensitivity for its substrate, which explains its participation in maintaining low steady-state levels of H2O2. We also show in vitro and in vivo that inactivation of Tpx1 by oxidation of its catalytic cysteine to a sulfinic acid is always preceded by a sulfinic acid form in a covalently linked dimer, which may be important for understanding the kinetics of Tpx1 inactivation. Furthermore, we provide evidence that a strain expressing Tpx1.C169S, lacking the resolving cysteine, can sustain aerobic growth, and we show that small reductants can modulate the activity of the mutant protein in vitro, probably by supplying a thiol group to substitute for cysteine 169. PMID:17409354

  17. Minimal conditions for protocell stationary growth.

    PubMed

    Bigan, Erwan; Steyaert, Jean-Marc; Douady, Stéphane

    2015-01-01

    We show that self-replication of a chemical system encapsulated within a membrane growing from within is possible without any explicit feature such as autocatalysis or metabolic closure, and without the need for their emergence through complexity. We use a protocell model relying upon random conservative chemical reaction networks with arbitrary stoichiometry, and we investigate the protocell's capability for self-replication, for various numbers of reactions in the network. We elucidate the underlying mechanisms in terms of simple minimal conditions pertaining only to the topology of the embedded chemical reaction network. A necessary condition is that each moiety must be fed, and a sufficient condition is that each siphon is fed. Although these minimal conditions are purely topological, by further endowing conservative chemical reaction networks with thermodynamically consistent kinetics, we show that the growth rate tends to increase on increasing the Gibbs energy per unit molecular weight of the nutrient and on decreasing that of the membrane precursor. PMID:25951201

  18. [Research advances in aerobic denitrifiers].

    PubMed

    Wang, Wei; Cai, Zu-cong; Zhong, Wen-hui; Wang, Guo-xiang

    2007-11-01

    This paper reviewed the varieties and characteristics of aerobic denitrifiers, their action mechanisms, and the factors affecting aerobic denitrification. Aerobic denitrifiers mainly include Pseudomonas, Alcaligenes, Paracoccus and Bacillus, which are either aerobic or facultative aerobic, and heterotrophic. They can denitrify under aerobic conditions, with the main product being N2O. They can also convert NH4+ -N to gas product. The nitrate reductase which catalyzes the denitrification is periplasmic nitrate reductase rather than membrane-bound nitrate reductase. Dissolved oxygen concentration and C/N ratio are the main factors affecting aerobic denitrification. The main methods for screening aerobic denitrifiers, such as intermittent aeration and selected culture, were also introduced. The research advances in the application of aerobic denitrifiers in aquaculture, waste water processing, and bio-degradation of organic pollutants, as well as the contributions of aerobic denitrifiers to soil nitrogen emission were summarized. PMID:18260473

  19. Atrazine mineralization potential of alluvial-aquifer sediments under aerobic conditions

    USGS Publications Warehouse

    McMahon, P.B.; Chapelle, F.H.; Jagucki, M.L.

    1992-01-01

    Microorganisms in aerobic incubations of alluvialaquifer sediment mineralized 9-14% of added [U-14C]-D-glucose in 24 h, compared with 17 m). Although first-order rate constants for 14CO2 production from the atrazine ethyl-2 carbon were low (<4.5 ?? 10-5-5.4 ?? 10-4 day-1), they may be significant in the time frame of groundwater flow. Laboratory-measured rate constants were similar to field-estimated rate constants [(3.2 ??1.4) ?? 10-4 day-1] required to mineralize the atrazine ethyl carbon in groundwater prior to its discharge into an adjacent river. These results are consistent with the occurrence of detectable levels of deethylatrazine, but not atrazine, in groundwater from monitoring wells at the river.

  20. Formation of aerobic granular sludge under adverse conditions: low DO and high ammonia.

    PubMed

    Zhang, Sheng-Hua; Zhang, Xiao-Hu; Lv, Lu; Wang, Qing; Jiang, Qipei

    2013-04-01

    In this study, two adverse environments: low dissolved oxygen (DO) and high ammonia concentration, were employed to investigate the morphology, interspecies quorum sensing, extracellular polymers (EPS) characterization and microbial communities in the formation of aerobic granular sludge. Results showed that low DO could promote filamentous bacterial outgrowth. Under high ammonia concentration aerobic granular sludge (AGS) could still be cultivated, although it was looser and lighter than the control group. During the early stage of the AGS cultivation process, Al-2 activity reached a peak value in all three reactors, and ultrasonic pre-treatment was not beneficial to the release of Al-2. During AGS formation, the production of polysaccharide exhibited increases from 12.2% to 40.3%, 49.6%, and 29.3%. And PS in R2 was the highest as the result of sludge bulking. PS/PN was 1.5 to approximately 8 in the three reactors. Three-dimensional EEM fuorescence spectroscopy variation indicated the change of protein in EPS, and the highest intensity of Peak T1 was obtained. The location shift of Peak T1 was not obvious, and Peaks A, C, and T2 shifted toward longer wavelengths (red shift) of 5 to approximately 60 nm, or shorter wavelengths (blue shift) of 10 to approximately 25 nm on the emission scale and/or excitation scale in all three reactors. This provided spectral information on the chemical structure changes. Bacteria in R3 had the highest species diversity, and all bacteria in beta-Proteobacteria were identified as genus Thauera, which suggested that simultaneous nitrification and denitrification occurred in R3. The filamentous bacteria in seed sludge and R2 were species-richer. There was a low abundance of filamentous bacteria in R1 and R3, which contributed to the granule structure stability. PMID:24620612

  1. Adhesion, Biofilm Formation, and Genomic Features of Campylobacter jejuni Bf, an Atypical Strain Able to Grow under Aerobic Conditions.

    PubMed

    Bronnec, Vicky; Turoňová, Hana; Bouju, Agnès; Cruveiller, Stéphane; Rodrigues, Ramila; Demnerova, Katerina; Tresse, Odile; Haddad, Nabila; Zagorec, Monique

    2016-01-01

    Campylobacter jejuni is the leading cause of bacterial enteritis in Europe. Human campylobacteriosis cases are frequently associated to the consumption of contaminated poultry meat. To survive under environmental conditions encountered along the food chain, i.e., from poultry digestive tract its natural reservoir to the consumer's plate, this pathogen has developed adaptation mechanisms. Among those, biofilm lifestyle has been suggested as a strategy to survive in the food environment and under atmospheric conditions. Recently, the clinical isolate C. jejuni Bf has been shown to survive and grow under aerobic conditions, a property that may help this strain to better survive along the food chain. The aim of this study was to evaluate the adhesion capacity of C. jejuni Bf and its ability to develop a biofilm. C. jejuni Bf can adhere to abiotic surfaces and to human epithelial cells, and can develop biofilm under both microaerobiosis and aerobiosis. These two conditions have no influence on this strain, unlike results obtained with the reference strain C. jejuni 81-176, which harbors only planktonic cells under aerobic conditions. Compared to 81-176, the biofilm of C. jejuni Bf is more homogenous and cell motility at the bottom of biofilm was not modified whatever the atmosphere used. C. jejuni Bf whole genome sequence did not reveal any gene unique to this strain, suggesting that its unusual property does not result from acquisition of new genetic material. Nevertheless some genetic particularities seem to be shared only between Bf and few others strains. Among the main features of C. jejuni Bf genome we noticed (i) a complete type VI secretion system important in pathogenicity and environmental adaptation; (ii) a mutation in the oorD gene involved in oxygen metabolism; and (iii) the presence of an uncommon insertion of a 72 amino acid coding sequence upstream from dnaK, which is involved in stress resistance. Therefore, the atypical behavior of this strain under

  2. Adhesion, Biofilm Formation, and Genomic Features of Campylobacter jejuni Bf, an Atypical Strain Able to Grow under Aerobic Conditions

    PubMed Central

    Bronnec, Vicky; Turoňová, Hana; Bouju, Agnès; Cruveiller, Stéphane; Rodrigues, Ramila; Demnerova, Katerina; Tresse, Odile; Haddad, Nabila; Zagorec, Monique

    2016-01-01

    Campylobacter jejuni is the leading cause of bacterial enteritis in Europe. Human campylobacteriosis cases are frequently associated to the consumption of contaminated poultry meat. To survive under environmental conditions encountered along the food chain, i.e., from poultry digestive tract its natural reservoir to the consumer’s plate, this pathogen has developed adaptation mechanisms. Among those, biofilm lifestyle has been suggested as a strategy to survive in the food environment and under atmospheric conditions. Recently, the clinical isolate C. jejuni Bf has been shown to survive and grow under aerobic conditions, a property that may help this strain to better survive along the food chain. The aim of this study was to evaluate the adhesion capacity of C. jejuni Bf and its ability to develop a biofilm. C. jejuni Bf can adhere to abiotic surfaces and to human epithelial cells, and can develop biofilm under both microaerobiosis and aerobiosis. These two conditions have no influence on this strain, unlike results obtained with the reference strain C. jejuni 81-176, which harbors only planktonic cells under aerobic conditions. Compared to 81-176, the biofilm of C. jejuni Bf is more homogenous and cell motility at the bottom of biofilm was not modified whatever the atmosphere used. C. jejuni Bf whole genome sequence did not reveal any gene unique to this strain, suggesting that its unusual property does not result from acquisition of new genetic material. Nevertheless some genetic particularities seem to be shared only between Bf and few others strains. Among the main features of C. jejuni Bf genome we noticed (i) a complete type VI secretion system important in pathogenicity and environmental adaptation; (ii) a mutation in the oorD gene involved in oxygen metabolism; and (iii) the presence of an uncommon insertion of a 72 amino acid coding sequence upstream from dnaK, which is involved in stress resistance. Therefore, the atypical behavior of this strain under

  3. QuadraPure-Supported Palladium Nanocatalysts for Microwave-Promoted Suzuki Cross-Coupling Reaction under Aerobic Condition

    PubMed Central

    Loh, Poh Lee; Juan, Joon Ching; Yarmo, Mohd Ambar; Yusop, Rahimi M.

    2014-01-01

    Cross-linked resin-captured palladium (XL-QPPd) was readily prepared by simple physical adsorption onto the high loading QuadraPure macroporous resin and a subsequent reduction process. To enhance the mechanical stability, entrapped palladium nanocatalysts were cross-linked with succinyl chloride. Both transmission electron microscopy images and X-ray diffraction analysis revealed that the palladium nanoparticles were well dispersed with diameters ranging in 4–10 nm. The catalyst performed good catalytic activity in microwave-promoted Suzuki cross-coupling reactions in water under aerobic condition with mild condition by using various aryl halides and phenylboronic acid. In addition, the catalyst showed an excellent recyclability without significant loss of catalytic activity. PMID:25054185

  4. Interaction of Cr(VI) reduction and denitrification by strain Pseudomonas aeruginosa PCN-2 under aerobic conditions.

    PubMed

    He, Da; Zheng, Maosheng; Ma, Tao; Li, Can; Ni, Jinren

    2015-06-01

    Inhibition of efficient denitrification in presence of toxic heavy metals is one of the current problems encountered in municipal wastewater treatment plants. This paper presents how to remove hexavalent chromium (Cr(VI)) and nitrate simultaneously by the novel strain Pseudomonas aeruginosa PCN-2 under aerobic conditions. The capability of strain PCN-2 for Cr(VI) and nitrate reduction was confirmed by PCR analysis of gene ChrR, napA, nirS, cnorB, nosZ, while Cr(VI) reduction was proved via an initial single-electron transfer through Cr(V) detection using electron paramagnetic resonance. Experimental results demonstrated that Cr(VI) and nitrate reduction by strain PCN-2 was much faster at pH 8-9 and higher initial cell concentration. However, increasing Cr(VI) concentration would inhibit aerobic denitrification process and result in an significant delay of nitrate reduction or N2O accumulation, which was attributed to competition between three electron acceptors, i.e., Cr(VI), O2 and nitrate in the electron transport chain. PMID:25795449

  5. Transcript profiles in cortical cells of maize primary root during ethylene-induced lysigenous aerenchyma formation under aerobic conditions

    PubMed Central

    Takahashi, Hirokazu; Yamauchi, Takaki; Rajhi, Imene; Nishizawa, Naoko K.; Nakazono, Mikio

    2015-01-01

    Background and Aims Internal aeration is important for plants to survive during periods of waterlogging, and the ability to form aerenchyma contributes by creating a continuous gas space between the shoots and the roots. Roots of maize (Zea mays) react to prolonged waterlogging by forming aerenchyma in root cortical cells by programmed cell death (PCD) in response to ethylene. The aim of this study was to understand the molecular mechanisms of ethylene-induced aerenchyma formation by identifying genes that are either up- or downregulated by ethylene treatment in maize root cortical cells. Methods Three-day-old maize seedlings were treated with ethylene for several hours under aerobic conditions. Cortical cells were isolated from the primary roots using laser microdissection (LM), and transcript profiles with and without ethylene treatment were compared by microarray. In addition, the effect on ethylene-induced aerenchyma formation of diphenyleneiodonium (DPI), an inhibitor of NADPH oxidases, was examined in order to assess the involvement of reactive oxygen species (ROS). Key Results A total of 223 genes were identified whose transcript levels were significantly increased or decreased by ethylene treatment in root cortical cells under aerobic conditions. Subsequent tissue-specific quantitative reverse-transcription PCR analyses revealed that ethylene increased the transcript levels of genes related to ethylene signalling in all of the root tissues examined (stelar cells, cortical cells and outer cell layers), whereas it increased the transcript levels of genes related to cell wall modification and proteolysis specifically in the cortical cells. DPI treatment inhibited the ethylene-induced aerenchyma formation and suppressed expression of some cell wall modification-related genes. Conclusions Several genes related to cell wall modification and proteolysis are specifically up- or downregulated in cortical cells during lysigenous aerenchyma formation under aerobic

  6. Microbiological Degradation of Malodorous Substances of Swine Waste under Aerobic Conditions

    PubMed Central

    Bourque, Denis; Bisaillon, Jean-Guy; Beaudet, Réjean; Sylvestre, M.; Ishaque, Muhammad; Morin, André

    1987-01-01

    Phenol, p-cresol, and volatile fatty acids (VFA; acetic, propionic, isobutyric, butyric, isovaleric, and valeric acids) were used as odor indicators of swine waste. Aeration of the waste allowed the indigenous microorganisms to grow and degrade these malodorous substances. The time required for degradation of these substances varied according to the waste used, and it was not necessarily related to their concentrations. Using a minimal medium which contained one of the malodorous compounds as sole carbon source, we have selected from swine waste microorganisms that can grow in the medium. The majority of these microorganisms were able to degrade the same substrate when inoculated in sterilized swine waste but with an efficiency varying from one strain to the other. None of these strains was able to degrade all malodorous substances studied. Within 6 days of incubation these selected strains degraded the following: Acinetobacter calcoaceticus, phenol and all VFA; Alcaligenes faecalis, p-cresol and all VFA; Corynebacterium glutamicum and Micrococcus sp., phenol, p-cresol, and acetic and propionic acids; Arthrobacter flavescens, all VFA. On a laboratory scale, the massive inoculation of swine waste with C. glutamicum or Micrococcus sp. accelerated degradation of the malodorous substances. However, this effect was not observed with all of the various swine wastes tested. These results suggest that an efficient deodorization process of various swine wastes could be developed at the farm level based on the aerobic indigenous microflora of each waste. PMID:16347254

  7. Effect of deficiencies in DNA repair on the toxicity of mitomycin C and porfiromycin to CHO cells under aerobic and hypoxic conditions.

    PubMed

    Hughes, C S; Irvin, C G; Rockwell, S

    1991-02-01

    A wild type Chinese hamster cell line (AA8) and three repair-deficient sublines of AA8 (EM9, UV4, and UV5) were used to study the nature of the cytotoxic lesions produced by the bioreductive alkylating agents mitomycin C and porfiromycin under aerobic and hypoxic conditions. The sensitivities of the repair-deficient sublines to the drugs varied markedly: EM9 was similar to AA8, whereas UV4 was exquisitely sensitive and UV5 was of intermediate sensitivity. Moreover, both the relative toxicities of the two drugs and the relative toxicities of each drug under aerobic and hypoxic conditions varied for the different cell lines. These data suggest that there are differences in the spectra of toxic lesions produced by mitomycin and porfiromycin and that there are differences in the lesions produced by these drugs under aerobic and hypoxic conditions. PMID:1899798

  8. Chemolithotrophic growth of the aerobic hyperthermophilic bacterium Thermocrinis ruber OC 14/7/2 on monothioarsenate and arsenite.

    PubMed

    Härtig, Cornelia; Lohmayer, Regina; Kolb, Steffen; Horn, Marcus A; Inskeep, William P; Planer-Friedrich, Britta

    2014-12-01

    Novel insights are provided regarding aerobic chemolithotrophic growth of Thermocrinis ruber OC14/7/2 on the electron donors arsenite and monothioarsenate. Thermocrinis ruber is a hyperthermophilic bacterium that thrives in pH-neutral to alkaline hot springs and grows on hydrogen, elemental sulfur, and thiosulfate. Our study showed that T. ruber can also utilize arsenite as sole electron donor producing arsenate. Growth rates of 0.024 h(-1) were lower than for oxidation of thiosulfate to sulfate (μ = 0.247 h(-1)). Fast growth was observed on monothioarsenate (μ = 0.359 h(-1)), comprising different abiotic and biotic redox interactions. The initial dominant process was abiotic transformation of monothioarsenate to arsenate and elemental sulfur, followed by microbial oxidation of sulfur to sulfate. Elevated microbial activity during stationary growth of T. ruber might be explained by microbial oxidation of thiosulfate and arsenite, both also products of abiotic monothioarsenate transformation. However, the observed rapid decrease of monothioarsenate, exceeding concentrations in equilibrium with its products, also indicates direct microbial oxidation of arsenic-bond S(-II) to sulfate. Free sulfide was oxidized abiotically too fast to play a role as electron donor for T. ruber. Our present laboratory and previous field studies suggest that thioarsenates can either indirectly or directly be used by (hyper)thermophiles in arsenic-sulfidic environments. PMID:25251939

  9. Modeling Hematite Bioreduction under Growth Conditions

    NASA Astrophysics Data System (ADS)

    Yu, J.; Chen, C.; Yeh, G.; Burgos, W. D.; Mynyard, M. L.

    2004-12-01

    The focus of this work is on simulating and analyzing bioreduction kinetics of natural hematite-coated sand by dissimilatory metal-reducing bacterium (DMRB), Shewanella putrefaciens CN32, under growth conditions with lactate as the electron donor. A reaction-based biogeochemical model was used. A series of batch experiments with different initial conditions were performed to determine the rate formulations/parameters for hematite bioreduction and related reactions. Three different kinetic reaction rate formations were used to model hematite bioreduction. The consistency of mass conservation equations was assessed. Assumptions regarding equilibrium reactions were also assessed. Column experiments focused on transient reactive transport were conducted under otherwise identical conditions, except that the flow rate was systematically varied. The determined rate formulations/parameters were systematically tested with these column experiments using a reactive biogeochemical transport model that coupled hydrologic transport and reactive biogeochemistry. The model simulated the hematite bioreduction of hematite-coated sand in column experiments reasonably well using rate formulation/parameters determined from batch experiments. This study supports the hypothesis that mechanistic-based reaction rates of batch experiments can be scaled up and ported to column experiments.

  10. TBA biodegradation in surface-water sediments under aerobic and anaerobic conditions

    USGS Publications Warehouse

    Bradley, P.M.; Landmeyer, J.E.; Chapelle, F.H.

    2002-01-01

    The potential for [U-14C] TBA biodegradation was examined in laboratory microcosms under a range of terminal electron accepting conditions. TBA mineralization to CO2 was substantial in surface-water sediments under oxic, denitrifying, or Mn(IV)-reducing conditions and statistically significant but low under SO4-reducing conditions. Thus, anaerobic TBA biodegradation may be a significant natural attenuation mechanism for TBA in the environment, and stimulation of in situ TBA bioremediation by addition of suitable terminal electron acceptors may be feasible. No degradation of [U-14C] TBA was observed under methanogenic or Fe(III)-reducing conditions.

  11. Intracellular Accumulation of Glycine in Polyphosphate-Accumulating Organisms in Activated Sludge, a Novel Storage Mechanism under Dynamic Anaerobic-Aerobic Conditions

    PubMed Central

    Nguyen, Hien Thi Thu; Kristiansen, Rikke; Vestergaard, Mette; Wimmer, Reinhard

    2015-01-01

    Dynamic anaerobic-aerobic feast-famine conditions are applied to wastewater treatment plants to select polyphosphate-accumulating organisms to carry out enhanced biological phosphorus removal. Acetate is a well-known substrate to stimulate this process, and here we show that different amino acids also are suitable substrates, with glycine as the most promising. 13C-labeled glycine and nuclear magnetic resonance (NMR) were applied to investigate uptake and potential storage products when activated sludge was fed with glycine under anaerobic conditions. Glycine was consumed by the biomass, and the majority was stored intracellularly as free glycine and fermentation products. Subsequently, in the aerobic phase without addition of external substrate, the stored glycine was consumed. The uptake of glycine and oxidation of intracellular metabolites took place along with a release and uptake of orthophosphate, respectively. Fluorescence in situ hybridization combined with microautoradiography using 3H-labeled glycine revealed uncultured actinobacterial Tetrasphaera as a dominant glycine consumer. Experiments with Tetrasphaera elongata as representative of uncultured Tetrasphaera showed that under anaerobic conditions it was able to take up labeled glycine and accumulate this and other labeled metabolites to an intracellular concentration of approximately 4 mM. All components were consumed under subsequent aerobic conditions. Intracellular accumulation of amino acids seems to be a novel storage strategy for polyphosphate-accumulating bacteria under dynamic anaerobic-aerobic feast-famine conditions. PMID:25956769

  12. Intracellular Accumulation of Glycine in Polyphosphate-Accumulating Organisms in Activated Sludge, a Novel Storage Mechanism under Dynamic Anaerobic-Aerobic Conditions.

    PubMed

    Nguyen, Hien Thi Thu; Kristiansen, Rikke; Vestergaard, Mette; Wimmer, Reinhard; Nielsen, Per Halkjær

    2015-07-01

    Dynamic anaerobic-aerobic feast-famine conditions are applied to wastewater treatment plants to select polyphosphate-accumulating organisms to carry out enhanced biological phosphorus removal. Acetate is a well-known substrate to stimulate this process, and here we show that different amino acids also are suitable substrates, with glycine as the most promising. (13)C-labeled glycine and nuclear magnetic resonance (NMR) were applied to investigate uptake and potential storage products when activated sludge was fed with glycine under anaerobic conditions. Glycine was consumed by the biomass, and the majority was stored intracellularly as free glycine and fermentation products. Subsequently, in the aerobic phase without addition of external substrate, the stored glycine was consumed. The uptake of glycine and oxidation of intracellular metabolites took place along with a release and uptake of orthophosphate, respectively. Fluorescence in situ hybridization combined with microautoradiography using (3)H-labeled glycine revealed uncultured actinobacterial Tetrasphaera as a dominant glycine consumer. Experiments with Tetrasphaera elongata as representative of uncultured Tetrasphaera showed that under anaerobic conditions it was able to take up labeled glycine and accumulate this and other labeled metabolites to an intracellular concentration of approximately 4 mM. All components were consumed under subsequent aerobic conditions. Intracellular accumulation of amino acids seems to be a novel storage strategy for polyphosphate-accumulating bacteria under dynamic anaerobic-aerobic feast-famine conditions. PMID:25956769

  13. Volatile chemical spoilage indexes of raw Atlantic salmon (salmo salar)stored under aerobic condition in relation to microbiological and sensory shelf lives

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The purpose of this investigation was to identify and quantify the volatile chemical spoilage indexes (CSIs) for raw Atlantic salmon (Salmo salar) fillets stored under aerobic storage conditions at 4, 10 and 21 degrees C in relation to the determined microbial and sensory shelf lives. The volatile o...

  14. Ability of Cecal Cultures to Inhibit Growth of Salmonella Typhimurium during Aerobic Incubation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Introduction: Poultry can serve as reservoirs for Salmonella; however, chicks provided cultures of cecal bacteria develop resistance to colonization by Salmonella. Research has indicated that cecal bacteria metabolize organic acids to produce substances that inhibit Salmonella growth. Purpose: The...

  15. Influence of pH on bile sensitivity amongst various strains of Listeria monocytogenes under aerobic and anaerobic conditions

    PubMed Central

    White, Sally J.; McClung, Daniel M.; Wilson, Jessica G.; Roberts, Brandy N.

    2015-01-01

    Listeria monocytogenes is a dangerous bacterium that causes the food-borne disease listeriosis and accounts for nearly 20 % of food-borne deaths. This organism can survive the body's natural defences within the digestive tract, including acidic conditions and bile. Although the bile response has been analysed, limited information is available concerning the ability of L. monocytogenes to resist bile under anaerobic conditions, especially at acidic pH, which mimics conditions within the duodenum. Additionally, it is not known how the bile response varies between serotypes. In this study, the survival of strains representing six serotypes was analysed under aerobic and anaerobic conditions following exposure to bile. Exposure to bile salts at acidic pH increased toxicity of bile, resulting in a significant reduction in survival for all strains tested. However, following this initial reduction, no significant reduction was observed for an additional 2 h except for strain 10403S (P = 0.002). Anaerobic cultivation increased bile resistance, but a significant increase was only observed in virulent strains when exposed to bile at pH 5.5. Exposure to pH 3.0 prior to bile decreased viability amongst avirulent strains in bile in acidic conditions; oxygen availability did not influence viability. Together, the data suggested that being able to sense and respond to oxygen availability may influence the expression of stress response mechanisms, and this response may correspond to disease outcome. Further research is needed on additional strains to determine how L. monocytogenes senses and responds to oxygen and how this varies between invasive and non-invasive strains. PMID:26307079

  16. Influence of pH on bile sensitivity amongst various strains of Listeria monocytogenes under aerobic and anaerobic conditions.

    PubMed

    White, Sally J; McClung, Daniel M; Wilson, Jessica G; Roberts, Brandy N; Donaldson, Janet R

    2015-11-01

    Listeria monocytogenes is a dangerous bacterium that causes the food-borne disease listeriosis and accounts for nearly 20% of food-borne deaths. This organism can survive the body's natural defences within the digestive tract, including acidic conditions and bile. Although the bile response has been analysed, limited information is available concerning the ability of L. monocytogenes to resist bile under anaerobic conditions, especially at acidic pH, which mimics conditions within the duodenum. Additionally, it is not known how the bile response varies between serotypes. In this study, the survival of strains representing six serotypes was analysed under aerobic and anaerobic conditions following exposure to bile. Exposure to bile salts at acidic pH increased toxicity of bile, resulting in a significant reduction in survival for all strains tested. However, following this initial reduction, no significant reduction was observed for an additional 2 h except for strain 10403S (P = 0.002). Anaerobic cultivation increased bile resistance, but a significant increase was only observed in virulent strains when exposed to bile at pH 5.5. Exposure to pH 3.0 prior to bile decreased viability amongst avirulent strains in bile in acidic conditions; oxygen availability did not influence viability. Together, the data suggested that being able to sense and respond to oxygen availability may influence the expression of stress response mechanisms, and this response may correspond to disease outcome. Further research is needed on additional strains to determine how L. monocytogenes senses and responds to oxygen and how this varies between invasive and non-invasive strains. PMID:26307079

  17. Simultaneous phosphorus uptake and denitrification by EBPR-r biofilm under aerobic conditions: effect of dissolved oxygen.

    PubMed

    Wong, Pan Yu; Ginige, Maneesha P; Kaksonen, Anna H; Cord-Ruwisch, Ralf; Sutton, David C; Cheng, Ka Yu

    2015-01-01

    A biofilm process, termed enhanced biological phosphorus removal and recovery (EBPR-r), was recently developed as a post-denitrification approach to facilitate phosphorus (P) recovery from wastewater. Although simultaneous P uptake and denitrification was achieved despite substantial intrusion of dissolved oxygen (DO >6 mg/L), to what extent DO affects the process was unclear. Hence, in this study a series of batch experiments was conducted to assess the activity of the biofilm under various DO concentrations. The biofilm was first allowed to store acetate (as internal storage) under anaerobic conditions, and was then subjected to various conditions for P uptake (DO: 0-8 mg/L; nitrate: 10 mg-N/L; phosphate: 8 mg-P/L). The results suggest that even at a saturating DO concentration (8 mg/L), the biofilm could take up P and denitrify efficiently (0.70 mmol e(-)/g total solids*h). However, such aerobic denitrification activity was reduced when the biofilm structure was physically disturbed, suggesting that this phenomenon was a consequence of the presence of oxygen gradient across the biofilm. We conclude that when a biofilm system is used, EBPR-r can be effectively operated as a post-denitrification process, even when oxygen intrusion occurs. PMID:26398030

  18. Conditional independence mapping of DIGE data reveals PDIA3 protein species as key nodes associated with muscle aerobic capacity

    PubMed Central

    Burniston, Jatin G.; Kenyani, Jenna; Gray, Donna; Guadagnin, Eleonora; Jarman, Ian H.; Cobley, James N.; Cuthbertson, Daniel J.; Chen, Yi-Wen; Wastling, Jonathan M.; Lisboa, Paulo J.; Koch, Lauren G.; Britton, Steven L.

    2014-01-01

    Profiling of protein species is important because gene polymorphisms, splice variations and post-translational modifications may combine and give rise to multiple protein species that have different effects on cellular function. Two-dimensional gel electrophoresis is one of the most robust methods for differential analysis of protein species, but bioinformatic interrogation is challenging because the consequences of changes in the abundance of individual protein species on cell function are unknown and cannot be predicted. We conducted DIGE of soleus muscle from male and female rats artificially selected as either high- or low-capacity runners (HCR and LCR, respectively). In total 696 protein species were resolved and LC–MS/MS identified proteins in 337 spots. Forty protein species were differentially (P < 0.05, FDR < 10%) expressed between HCR and LCR and conditional independence mapping found distinct networks within these data, which brought insight beyond that achieved by functional annotation. Protein disulphide isomerase A3 emerged as a key node segregating with differences in aerobic capacity and unsupervised bibliometric analysis highlighted further links to signal transducer and activator of transcription 3, which were confirmed by western blotting. Thus, conditional independence mapping is a useful technique for interrogating DIGE data that is capable of highlighting latent features. PMID:24769234

  19. Identification and Quantification of Volatile Chemical Spoilage Indexes Associated with Bacterial Growth Dynamics in Aerobically Stored Chicken.

    PubMed

    Mikš-Krajnik, Marta; Yoon, Yong-Jin; Ukuku, Dike O; Yuk, Hyun-Gyun

    2016-08-01

    Volatile organic compounds (VOCs) as chemical spoilage indexes (CSIs) of raw chicken breast stored aerobically at 4, 10, and 21 °C were identified and quantified using solid phase microextraction (SPME) combined with gas chromatography-mass spectrometry (GC-MS). The growth dynamics of total viable count (TVC), psychrotrophs, Pseudomonas spp., lactic acid bacteria (LAB), Brochothrix thermosphacta and H2 S producing bacteria were characterized based on maximum growth rates (μmax ), maximal microbial concentration (Nmax ) and at the moment of microbial shelf life (Svalues ), calculated from Gompertz-fitted growth curves. Pseudomonas spp. was predominant species, while B. thermosphacta was characterized by the highest μmax . The microbiological and sensory shelf lives were estimated based on TVC, Pseudomonas spp., and B. thermosphacta counts and sensory evaluation, respectively. Among 27 VOCs identified by GC-MS in spoiled chicken samples, ethanol (EtOH), 1-butanol-3-methyl (1But-3M), and acetic acid (C2 ) achieved the highest Pearson's correlation coefficients of 0.66, 0.61, and 0.59, respectively, with TVC, regardless of storage temperature. Partial least squares (PLS) regression revealed that the synthesis of 1But-3M and C2 was most likely induced by the metabolic activity of B. thermosphacta and LAB, while EtOH was attributed to Pseudomonas spp. The increase in concentration of selected volatile spoilage markers (EtOH, 1But-3M, and C2 ) in the headspace over spoiled chicken breast was found to be statistically significant (P < 0.05) with TVC growth. These findings highlight the possibility of analyzing the combination of 3 selected spoilage markers: EtOH, 1But-3M, and C2 as rapid evaluation for poultry quality testing using SPME-GC-MS. PMID:27332555

  20. Mathematic modeling for optimum conditions on aflatoxin B₁degradation by the aerobic bacterium Rhodococcus erythropolis.

    PubMed

    Kong, Qing; Zhai, Cuiping; Guan, Bin; Li, Chunjuan; Shan, Shihua; Yu, Jiujiang

    2012-11-01

    Response surface methodology was employed to optimize the degradation conditions of AFB₁ by Rhodococcus erythropolis in liquid culture. The most important factors that influence the degradation, as identified by a two-level Plackett-Burman design with six variables, were temperature, pH, liquid volume, inoculum size, agitation speed and incubation time. Central composite design (CCD) and response surface analysis were used to further investigate the interactions between these variables and to optimize the degradation efficiency of R. erythropolis based on a second-order model. The results demonstrated that the optimal parameters were: temperature, 23.2 °C; pH, 7.17; liquid volume, 24.6 mL in 100-mL flask; inoculum size, 10%; agitation speed, 180 rpm; and incubation time, 81.9 h. Under these conditions, the degradation efficiency of R. erythropolis could reach 95.8% in liquid culture, which was increased by about three times as compared to non-optimized conditions. The result by mathematic modeling has great potential for aflatoxin removal in industrial fermentation such as in food processing and ethanol production. PMID:23202311

  1. Mathematic Modeling for Optimum Conditions on Aflatoxin B1 Degradation by the Aerobic Bacterium Rhodococcus erythropolis

    PubMed Central

    Kong, Qing; Zhai, Cuiping; Guan, Bin; Li, Chunjuan; Shan, Shihua; Yu, Jiujiang

    2012-01-01

    Response surface methodology was employed to optimize the degradation conditions of AFB1 by Rhodococcus erythropolis in liquid culture. The most important factors that influence the degradation, as identified by a two-level Plackett-Burman design with six variables, were temperature, pH, liquid volume, inoculum size, agitation speed and incubation time. Central composite design (CCD) and response surface analysis were used to further investigate the interactions between these variables and to optimize the degradation efficiency of R. erythropolis based on a second-order model. The results demonstrated that the optimal parameters were: temperature, 23.2 °C; pH, 7.17; liquid volume, 24.6 mL in 100-mL flask; inoculum size, 10%; agitation speed, 180 rpm; and incubation time, 81.9 h. Under these conditions, the degradation efficiency of R. erythropolis could reach 95.8% in liquid culture, which was increased by about three times as compared to non-optimized conditions. The result by mathematic modeling has great potential for aflatoxin removal in industrial fermentation such as in food processing and ethanol production. PMID:23202311

  2. Plant growth conditions alter phytolith carbon

    PubMed Central

    Gallagher, Kimberley L.; Alfonso-Garcia, Alba; Sanchez, Jessica; Potma, Eric O.; Santos, Guaciara M.

    2015-01-01

    Many plants, including grasses and some important human food sources, accumulate, and precipitate silica in their cells to form opaline phytoliths. These phytoliths contain small amounts of organic matter (OM) that are trapped during the process of silicification. Previous work has suggested that plant silica is associated with compounds such as proteins, lipids, lignin, and carbohydrate complexes. It is not known whether these compounds are cellular components passively encapsulated as the cell silicifies, polymers actively involved in the precipitation process or random compounds assimilated by the plant and discarded into a “glass wastebasket.” Here, we used Raman spectroscopy to map the distribution of OM in phytoliths, and to analyze individual phytoliths isolated from Sorghum bicolor plants grown under different laboratory treatments. Using mapping, we showed that OM in phytoliths is distributed throughout the silica and is not related to dark spots visible in light microscopy, previously assumed to be the repository for phytolith OM. The Raman spectra exhibited common bands indicative of C-H stretching modes of general OM, and further more diagnostic bands consistent with carbohydrates, lignins, and other OM. These Raman spectra exhibited variability of spectral signatures and of relative intensities between sample treatments indicating that differing growth conditions altered the phytolith carbon. This may have strong implications for understanding the mechanism of phytolith formation, and for use of phytolith carbon isotope values in dating or paleoclimate reconstruction. PMID:26442066

  3. Plant growth conditions alter phytolith carbon.

    PubMed

    Gallagher, Kimberley L; Alfonso-Garcia, Alba; Sanchez, Jessica; Potma, Eric O; Santos, Guaciara M

    2015-01-01

    Many plants, including grasses and some important human food sources, accumulate, and precipitate silica in their cells to form opaline phytoliths. These phytoliths contain small amounts of organic matter (OM) that are trapped during the process of silicification. Previous work has suggested that plant silica is associated with compounds such as proteins, lipids, lignin, and carbohydrate complexes. It is not known whether these compounds are cellular components passively encapsulated as the cell silicifies, polymers actively involved in the precipitation process or random compounds assimilated by the plant and discarded into a "glass wastebasket." Here, we used Raman spectroscopy to map the distribution of OM in phytoliths, and to analyze individual phytoliths isolated from Sorghum bicolor plants grown under different laboratory treatments. Using mapping, we showed that OM in phytoliths is distributed throughout the silica and is not related to dark spots visible in light microscopy, previously assumed to be the repository for phytolith OM. The Raman spectra exhibited common bands indicative of C-H stretching modes of general OM, and further more diagnostic bands consistent with carbohydrates, lignins, and other OM. These Raman spectra exhibited variability of spectral signatures and of relative intensities between sample treatments indicating that differing growth conditions altered the phytolith carbon. This may have strong implications for understanding the mechanism of phytolith formation, and for use of phytolith carbon isotope values in dating or paleoclimate reconstruction. PMID:26442066

  4. Storage and degradation of poly-beta-hydroxybutyrate in activated sludge under aerobic conditions.

    PubMed

    Dircks, K; Henze, M; van Loosdrecht, M C; Mosbaek, H; Aspegren, H

    2001-06-01

    This research analyses the accumulation and degradation of poly-beta-hydroxybutyrate (PHB) in experiments with pulse addition of acetate to samples of activated sludge from pilot-plant and full-scale wastewater treatment plants. The experiments are divided into two periods: a feast period defined as the time when acetate is consumed and a famine period when the added acetate has been exhausted. In the feast period the significant process occurring is the production of PHB from acetate. The produced PHB is utilised in the famine period for production of glycogen and biomass. According to modelling results approximately 90% of the total potential growth occurs in the famine period utilising the stored PHB. The degradation rate for PHB in the famine period is found to be dependent on the level of PHB obtained at the end of the feast period. It was found that multiple order kinetics gives a good description of the rate of PHB degradation. The examined sludge of low SRT origin is found to degrade PHB faster than long SRT sludge at high fractions of PHB. The observed yield of glycogen on PHB in the famine period is in the range of 0.22-0.33 g COD/g COD depending on the SRT. The storage pool of glycogen in the examined sludge is more slowly degraded than PHB (COD/COD/h). PMID:11358308

  5. Coenzyme B12 can be produced by engineered Escherichia coli under both anaerobic and aerobic conditions.

    PubMed

    Ko, Yeounjoo; Ashok, Somasundar; Ainala, Satish Kumar; Sankaranarayanan, Mugesh; Chun, Ah Yeong; Jung, Gyoo Yeol; Park, Sunghoon

    2014-12-01

    Coenzyme B12 (Vitamin B12 ) is one of the most complex biomolecules and an essential cofactor required for the catalytic activity of many enzymes. Pseudomonas denitrificans synthesizes coenzyme B12 in an oxygen-dependent manner using a pathway encoded by more than 25 genes that are located in six different operons. Escherichia coli, a robust and suitable host for metabolic engineering was used to produce coenzyme B12 . These genes were cloned into three compatible plasmids and expressed heterologously in E. coli BL21 (DE3). Real-time PCR, SDS-PAGE analysis and bioassay showed that the recombinant E. coli expressed the coenzyme B12 synthetic genes and successfully produced coenzyme B12 . However, according to the quantitative determination by inductively coupled plasma-mass spectrometry, the amount of coenzyme B12 produced by the recombinant E. coli (0.21 ± 0.02 μg/g cdw) was approximately 13-fold lower than that by P. denitrificans (2.75 ± 0.22 μg/g cdw). Optimization of the culture conditions to improve the production of coenzyme B12 by the recombinant E. coli was successful, and the highest titer (0.65 ± 0.03 μg/g cdw) of coenzyme B12 was obtained. Interestingly, although the synthesis of coenzyme B12 in P. denitrificans is strictly oxygen-dependent, the recombinant E. coli could produce coenzyme B12 under anaerobic conditions. PMID:25146562

  6. Rhodobacter sphaeroides mutants which accumulate 5-aminolevulinic acid under aerobic and dark conditions.

    PubMed

    Nishikawa, S; Watanabe, K; Tanaka, T; Miyachi, N; Hotta, Y; Murooka, Y

    1999-01-01

    The photosynthetic bacterium Rhodobacter sphaeroides accumulates 5-aminolevulinic acid (ALA), which is a precursor in tetrapyrrole biosynthesis, under light illumination and upon addition of levulinic acid as an inhibitor of ALA dehydratase. To generate an industrial strain which produces ALA in the absence of light, we sequentially mutated R. sphaeroides CR-286 using N-methyl-N'-nitro-N-nitrosoguanidine (NTG). The mutant strains were screened by cultivating in the absence of light and assayed for ALA by the Ehrlich reaction in a 96-well microtiter plate. The mutant strain CR-386, derived from R. sphaeroides CR-286, was selected as a mutant that exhibited significant ALA accumulation. While CR-286 required light illumination for ALA production, CR-386 was able to accumulate 1.5 mM ALA in the presence of 50 mM glucose, 60 mM glycine, 15 mM levulinic acid and 1.0% (w/v) yeast extract under conditions of agitation in the absence of light. The mutant strain CR-450, derived from strain CR-386, was selected further as a mutant that exhibited significant ALA accumulation but no accumulation of aminoacetone, analogue of ALA. CR-450 accumulated 3.8 mM ALA under the same conditions. In the presence of 50 mM glucose, 60 mM glycine, 5 mM levulinic acid and 1.0% (w/v) yeast extract, the mutant strain CR-520, derived from strain CR-450, and strain CR-606, derived from strain CR-520, accumulated 8.1 mM and 11.2 mM ALA, respectively. In batch fermentation, the strain CR-606 accumulated 20 mM ALA over 18 h after the addition of glycine, levulinic acid, glucose and yeast extract. PMID:16232557

  7. Molecular analysis of the biomass of a fluidized bed reactor treating synthetic vinasse at anaerobic and micro-aerobic conditions.

    PubMed

    Rodríguez, Elisa; Lopes, Alexandre; Fdz-Polanco, María; Stams, Alfons J M; García-Encina, Pedro A

    2012-03-01

    The microbial communities (Bacteria and Archaea) established in an anaerobic fluidized bed reactor used to treat synthetic vinasse (betaine, glucose, acetate, propionate, and butyrate) were characterized by denaturing gradient gel electrophoresis (DGGE) and phylogenetic analysis. This study was focused on the competitive and syntrophic interactions between the different microbial groups at varying influent substrate to sulfate ratios of 8, 4, and 2 and anaerobic or micro-aerobic conditions. Acetogens detected along the anaerobic phases at substrate to sulfate ratios of 8 and 4 seemed to be mainly involved in the fermentation of glucose and betaine, but they were substituted by other sugar or betaine degraders after oxygen application. Typical fatty acid degraders that grow in syntrophy with methanogens were not detected during the entire reactor run. Likely, sugar and betaine degraders outnumbered them in the DGGE analysis. The detected sulfate-reducing bacteria (SRB) belonged to the hydrogen-utilizing Desulfovibrio. The introduction of oxygen led to the formation of elemental sulfur (S(0)) and probably other sulfur compounds by sulfide-oxidizing bacteria (γ-Proteobacteria). It is likely that the sulfur intermediates produced from sulfide oxidation were used by SRB and other microorganisms as electron acceptors, as was supported by the detection of the sulfur respiring Wolinella succinogenes. Within the Archaea population, members of Methanomethylovorans and Methanosaeta were detected throughout the entire reactor operation. Hydrogenotrophic methanogens mainly belonging to the genus Methanobacterium were detected at the highest substrate to sulfate ratio but rapidly disappeared by increasing the sulfate concentration. PMID:21861082

  8. Solidification under microgravity conditions - Dendritic growth

    NASA Technical Reports Server (NTRS)

    Glicksman, M. E.; Hahn, R. C.; Lograsso, T. A.; Rubinstein, E. R.; Winsa, E.

    1987-01-01

    The experimental approach and apparatus of a zero-gravity active crystal growth experiment to test dendritic growth theory at low supercoolings are discussed. The experiment consists of 20 experimental cycles. Estimates have been made as to how low gravitational accelerations would have to be reduced to observe convection-free dendritic growth at supercoolings from 0.01-1.0 K. The experiment requires temperature control of + or - 2 mK and photographic resolution of a few microns with a depth of field of + or - 6 mm. The thermostatic bath and temperature control system, photographic system, growth chamber, and dendrite detection system are described in detail.

  9. Laboratory Study of Chemical Speciation of Mercury in Lake Sediment and Water under Aerobic and Anaerobic Conditions

    PubMed Central

    Regnell, Olof; Tunlid, Anders

    1991-01-01

    Chemical speciation and partitioning of radiolabeled HgCl2 were studied in model aquatic systems consisting of undisturbed eutrophic lake sediment and water in plastic cylinders. The cylinders were either gradually made anaerobic by a gentle flow of N2-CO2 or kept aerobic by air flow. The proportion of methylated 203Hg was significantly higher, in both water and sediment, in the anaerobic systems than in the aerobic systems. The composition and total concentration of fatty acids originating from bacterial phospholipids, as well as the concentration of vitamin B12, including related cobalamins, were similar in sediments from the anaerobic and aerobic systems. Bacterial cell numbers were, on average, 3.6 times higher in the anaerobic water columns than in the aerobic ones. Volatilization of 203Hg occurred in all systems except in an autoclaved control and was of similar magnitudes in the anaerobic and aerobic systems. Incorporation of 203Hg into the sediment was significantly faster in the aerobic systems than in the anaerobic systems. These results suggest that episodes of anoxia in bottom waters and sediment cause an increase in net mercury methylation and, hence, an increase in bioavailable mercury. PMID:16348444

  10. Molecular insight into activated sludge producing polyhydroxyalkanoates under aerobic-anaerobic conditions.

    PubMed

    Ciesielski, Slawomir; Pokoj, Tomasz; Klimiuk, Ewa

    2008-08-01

    One of the options enabling more economic production of polyhydroxyalkanoates compared to pure cultures is the application of mixed cultures. The use of a microbial community in a sequencing batch reactor has a few advantages: a simple process control, no necessity for sterile processing, and possibilities of using cheap substrates as a source of carbon. Nevertheless, while cultivation methods to achieve high PHAs biomass concentration and high productivity in wild and recombinant strains are defined, knowledge about the cultivation strategy for PHAs production by mixed culture and species composition of bacterial communities is still very limited. The main object of this study was to characterize on the molecular level the composition and activity of PHAs producing microorganism in activated sludge cultivated under oxygen limitation conditions. PHAs producers were detected using a PCR technique and the created PHA synthase gene library was analyzed by DNA sequencing. The obtained results indicate that PHAs-producers belonged to Pseudomonas sp., and possessed genes coding for mcl-PHA synthase. The kinetics of mcl-PHA synthase expression was relatively estimated using real-time PCR technology at several timepoints. Performed quantitative and qualitative analysis of total bacterial activity showed that there were differences in total activity during the process but differential expression of various groups of microorganisms examined by using DGGE was not observed. PMID:18418634

  11. Optimization of operation conditions for the startup of aerobic granular sludge reactors biologically removing carbon, nitrogen, and phosphorous.

    PubMed

    Lochmatter, Samuel; Holliger, Christof

    2014-08-01

    The transformation of conventional flocculent sludge to aerobic granular sludge (AGS) biologically removing carbon, nitrogen and phosphorus (COD, N, P) is still a main challenge in startup of AGS sequencing batch reactors (AGS-SBRs). On the one hand a rapid granulation is desired, on the other hand good biological nutrient removal capacities have to be maintained. So far, several operation parameters have been studied separately, which makes it difficult to compare their impacts. We investigated seven operation parameters in parallel by applying a Plackett-Burman experimental design approach with the aim to propose an optimized startup strategy. Five out of the seven tested parameters had a significant impact on the startup duration. The conditions identified to allow a rapid startup of AGS-SBRs with good nutrient removal performances were (i) alternation of high and low dissolved oxygen phases during aeration, (ii) a settling strategy avoiding too high biomass washout during the first weeks of reactor operation, (iii) adaptation of the contaminant load in the early stage of the startup in order to ensure that all soluble COD was consumed before the beginning of the aeration phase, (iv) a temperature of 20 °C, and (v) a neutral pH. Under such conditions, it took less than 30 days to produce granular sludge with high removal performances for COD, N, and P. A control run using this optimized startup strategy produced again AGS with good nutrient removal performances within four weeks and the system was stable during the additional operation period of more than 50 days. PMID:24784454

  12. Osmium(0) nanoclusters stabilized by zeolite framework; highly active catalyst in the aerobic oxidation of alcohols under mild conditions.

    PubMed

    Zahmakiran, Mehmet; Akbayrak, Serdar; Kodaira, Tetsuya; Ozkar, Saim

    2010-08-28

    Osmium(0) nanoclusters stabilized by zeolite-Y framework were reproducibly prepared by a simple two step procedure involving the incorporation of osmium(III) cations into the zeolite matrix by ion-exchange, followed by their reduction within the cavities of zeolite with sodium borohydride in aqueous solution all at room temperature. The composition and morphology of osmium(0) nanoclusters stabilized by zeolite framework, as well as the integrity and crystallinity of the host material were investigated by using ICP-OES, XRD, XPS, SEM, TEM, HRTEM, TEM/EDX, mid-IR, far-IR spectroscopies, and N(2)-adsorption/desorption technique. The results of the multiprong analysis reveal the formation of osmium(0) nanoclusters within the cavities of zeolite-Y without causing alteration in the framework lattice, formation of mesopores, or loss in the crystallinity of the host material. More importantly, far-IR studies showed that after the reduction of Os(3+) cations by sodium borohydride the Na(+) cations reoccupy their authentic cation sites restoring the integrity of zeolite-Y. The catalytic activity of osmium(0) nanoclusters stabilized by zeolite framework was tested in the aerobic oxidation of activated, unactivated and heteroatom containing alcohols to carbonyl compounds and was found to provide high activity and selectivity even under mild conditions (80 degrees C and 1 atm O(2) or air). Moreover, they were found to be stable enough to be isolated and bottled as solid material, which can be reused as active catalyst under the identical conditions of the first run. PMID:20614055

  13. Proline biosynthesis augments tumor cell growth and aerobic glycolysis: involvement of pyridine nucleotides

    PubMed Central

    Liu, Wei; Hancock, Chad N.; Fischer, Joseph W.; Harman, Meredith; Phang, James M.

    2015-01-01

    The metabolism of the nonessential amino acid proline contributes to tumor metabolic reprogramming. Previously we showed that MYC increases proline biosynthesis (PB) from glutamine. Here we show MYC increases the expression of the enzymes in PB at both protein and mRNA levels. Blockade of PB decreases tumor cell growth and energy production. Addition of Δ1-pyrroline-5-carboxylate (P5C) or proline reverses the effects of P5C synthase knockdown but not P5C reductases knockdown. Importantly, the reversal effect of proline was blocked by concomitant proline dehydrogenase/oxidase (PRODH/POX) knockdown. These findings suggest that the important regulatory contribution of PB to tumor growth derives from metabolic cycling between proline and P5C rather than product proline or intermediate P5C. We further document the critical role of PB in maintaining pyridine nucleotide levels by connecting the proline cycle to glycolysis and to the oxidative arm of the pentose phosphate pathway. These findings establish a novel function of PB in tumorigenesis, linking the reprogramming of glucose, glutamine and pyridine nucleotides, and may provide a novel target for antitumor therapy. PMID:26598224

  14. Spectroscopic studies of the effect of aerobic conditions on the chemical characteristics of humic acid in landfill leachate and its implication for the environment.

    PubMed

    Xiaoli, Chai; Yongxia, Hao; Guixiang, Liu; Xin, Zhao; Youcai, Zhao

    2013-05-01

    Humic acids (HAs) that extracted from leachates from semi-aerobic and anaerobic landfills test field at different stabilization times were characterized by elemental composition, Fourier transform infrared spectroscopy (FTIR), and Carbon-13 Cross-Polarization Magic-Angle-Spinning Nuclear Magnetic Resonance ((13)C CP/MAS NMR). The higher sulfur (S) content of HA in the anaerobic landfill leachate after a short stabilization time showed that the S released from the organic matter degradation was more easily stabilized under anaerobic conditions, which indicate that HA from anaerobic landfill leachate was more chemically reactive and played a more important role in mobilizing heavy metal, especially mercury, at early landfill stabilization times. However, the S content of HA from the semi-aerobic landfill increased over time, suggesting that more S was stabilized in HA as the landfill stabilization time was extended. The analytical results for the FTIR and NMR showed that the HA from the anaerobic landfill contained more aromatic groups, while HA from the semi-aerobic landfill had more oxygen-containing groups. The aromatic components of the HA from both the anaerobic and semi-aerobic landfills increased over time, suggesting that the maturity and humification degree of HA increased during the stabilization process. PMID:23461837

  15. Investigation of oxidative phosphorylation in continuous cultures. A non-equilibrium thermodynamic approach to energy transduction for Escherichia coli in aerobic condition

    NASA Astrophysics Data System (ADS)

    Ghafuri, Mohazabeh; Nosrati, Mohsen; Hosseinkhani, Saman

    2015-03-01

    Adenosine triphosphate (ATP) production in living cells is very important. Different researches have shown that in terms of mathematical modeling, the domain of these investigations is essentially restricted. Recently the thermodynamic models have been suggested for calculation of the efficiency of oxidative phosphorylation process and rate of energy loss in animal cells using chemiosmotic theory and non-equilibrium thermodynamics equations. In our previous work, we developed a mathematical model for mitochondria of animal cells. In this research, according to similarities between oxidative phosphorylation process in microorganisms and animal cells, Golfar's model was developed to predict the non-equilibrium thermodynamic behavior of the oxidative phosphorylation process for bacteria in aerobic condition. With this model the rate of energy loss, P/O ratio, and efficiency of oxidative phosphorylation were calculated for Escherichia coli in aerobic condition. The results then were compared with experimental data given by other authors. The thermodynamic model had an acceptable agreement with the experimental data.

  16. Differential Label-free Quantitative Proteomic Analysis of Shewanella oneidensis Cultured under Aerobic and Suboxic Conditions by Accurate Mass and Time Tag Approach

    SciTech Connect

    Fang, Ruihua; Elias, Dwayne A.; Monroe, Matthew E.; Shen, Yufeng; McIntosh, Martin; Wang, Pei; Goddard, Carrie D.; Callister, Stephen J.; Moore, Ronald J.; Gorby, Yuri A.; Adkins, Joshua N.; Fredrickson, Jim K.; Lipton, Mary S.; Smith, Richard D.

    2006-04-01

    We describe the application of liquid chromatography coupled to mass spectrometry (LC/MS) without the use of stable isotope labeling for differential quantitative proteomics analysis of whole cell lysates of Shewanella oneidensis MR-1 cultured under aerobic and sub-oxic conditions. Liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) was used to initially identify peptide sequences, and LC coupled to Fourier transform ion cyclotron resonance mass spectrometry (LC-FTICR) was used to confirm these identifications, as well as measure relative peptide abundances. 2343 peptides, covering 668 proteins were identified with high confidence and quantified. Among these proteins, a subset of 56 changed significantly using statistical approaches such as SAM, while another subset of 56 that were annotated as performing housekeeping functions remained essentially unchanged in relative abundance. Numerous proteins involved in anaerobic energy metabolism exhibited up to a 10-fold increase in relative abundance when S. oneidensis is transitioned from aerobic to sub-oxic conditions.

  17. Aerobic and anaerobic cellulase production by Cellulomonas uda.

    PubMed

    Poulsen, Henrik Vestergaard; Willink, Fillip Wolfgang; Ingvorsen, Kjeld

    2016-10-01

    Cellulomonas uda (DSM 20108/ATCC 21399) is one of the few described cellulolytic facultative anaerobes. Based on these characteristics, we initiated a physiological study of C. uda with the aim to exploit it for cellulase production in simple bioreactors with no or sporadic aeration. Growth, cellulase activity and fermentation product formation were evaluated in different media under both aerobic and anaerobic conditions and in experiments where C. uda was exposed to alternating aerobic/anaerobic growth conditions. Here we show that C. uda behaves as a true facultative anaerobe when cultivated on soluble substrates such as glucose and cellobiose, but for reasons unknown cellulase activity is only induced under aerobic conditions on insoluble cellulosic substrates and not under anaerobic conditions. These findings enhance knowledge on the limited number of described facultative cellulolytic anaerobes, and in addition it greatly limits the utility of C. uda as an 'easy to handle' cellulase producer with low aeration demands. PMID:27154570

  18. Anaerobic and aerobic transformation of TNT

    SciTech Connect

    Kulpa, C.F.; Boopathy, R.; Manning, J.

    1996-12-31

    Most studies on the microbial metabolism of nitroaromatic compounds have used pure cultures of aerobic microorganisms. In many cases, attempts to degrade nitroaromatics under aerobic conditions by pure cultures result in no mineralization and only superficial modifications of the structure. However, mixed culture systems properly operated result in the transformation of 2,4,6-trinitrotoluene (TNT) and in some cases mineralization of TNT occurs. In this paper, the mixed culture system is described with emphasis on intermediates and the characteristics of the aerobic microbial process including the necessity for a co-substrate. The possibility of removing TNT under aerobic/anoxic conditions is described in detail. Another option for the biodegradation of TNT and nitroaromatics is under anaerobic, sulfate reducing conditions. In this instance, the nitroaromatic compounds undergo a series of reductions with the formation of amino compounds. TNT under sulfate reducing conditions is reduced to triaminotoluene presumably by the enzyme nitrite reductase, which is commonly found in many Desulfovibrio spp. The removal of nitro groups from TNT is achieved by a series of reductive reactions with the formation of ammonia and toluene by Desulfovibrio sp. (B strain). These metabolic processes could be applied to other nitroaromatic compounds like nitrobenzene, nitrobenzoic acids, nitrophenols, and aniline. The data supporting the anaerobic transformation of TNT under different growth condition are reviewed in this report.

  19. [Antagonistic interactions between stress factors during the growth of microorganisms under conditions simulating the parameters of their natural ecotopes].

    PubMed

    Arzumanian, V G; Voronina, N A; Geĭdebrekht, O V; Shelemekh, O V; Plakunov, V K; Beliaev, S S

    2002-01-01

    Two stress factors, hypoxia (microaerobic conditions) and a high salt concentration, if applied simultaneously to aerobic microorganisms, display an antagonistic mode of interaction. As a result, the NaCl level that is usually optimal for moderate halophiles (5-6%) becomes optimal for the growth of weak halophiles (Rhodococcus erythropolis and Shewanella sp. CN32); the halotolerant yeast Yarrowia lypolytica acquires halophilic properties (with a growth optimum at a NaCl concentration of 10%), and the growth rate of the extremely halophilic Halobacterium salinarum increases at supraoptimal salt concentrations (25-34%). This phenomenon is apparently due to multiple changes in metabolic reactions. In particular, high salt concentrations suppress respiration and the formation of enzymes (superoxide dismutase and catalase) that protect the cell from toxic oxygen species. Therefore, establishment of microaerobic conditions compensates for the loss of these protective mechanisms and enables cell growth at higher salt concentrations than under aerobic conditions. Of some importance can also be the increase in the intracellular concentrations of osmoprotectants caused by the suppression of their intracellular oxidation. The implications of this phenomenon for the ecophysiology of microorganisms (including oiloxidizing species) and for the classification of weak and moderate halophiles are discussed. PMID:12024812

  20. Aerobic microbial mineralization of dichloroethene as sole carbon substrate

    USGS Publications Warehouse

    Bradley, P.M.; Chapelle, F.H.

    2000-01-01

    Microorganisms indigenous to the bed sediments of a black- water stream utilized 1,2-dichloroethene (1,2-DCE) as a sole carbon substrate for aerobic metabolism. Although no evidence of growth was observed in the minimal salts culture media used in this study, efficient aerobic microbial mineralization of 1,2-DCE as sole carbon substrate was maintained through three sequential transfers (107 final dilution) of the original environmental innoculum. These results indicate that 1,2-DCE can be utilized as a primary substrate to support microbial metabolism under aerobic conditions.Microorganisms indigenous to the bed sediments of a black-water stream utilized 1,2-dichloroethene (1,2-DCE) as a sole carbon substrate for aerobic metabolism. Although no evidence of growth was observed in the minimal salts culture media used in this study, efficient aerobic microbial mineralization of 1,2-DCE as sole carbon substrate was maintained through three sequential transfers (107 final dilution) of the original environmental innoculum. These results indicate that 1,2-DCE can be utilized as a primary substrate to support microbial metabolism under aerobic conditions.

  1. Degradation of Polycyclic Aromatic Hydrocarbons at Low Temperature under Aerobic and Nitrate-Reducing Conditions in Enrichment Cultures from Northern Soils

    PubMed Central

    Eriksson, Mikael; Sodersten, Erik; Yu, Zhongtang; Dalhammar, Gunnel; Mohn, William W.

    2003-01-01

    The potential for biodegradation of polycyclic aromatic hydrocarbons (PAHs) at low temperature and under anaerobic conditions is not well understood, but such biodegradation would be very useful for remediation of polluted sites. Biodegradation of a mixture of 11 different PAHs with two to five aromatic rings, each at a concentration of 10 μg/ml, was studied in enrichment cultures inoculated with samples of four northern soils. Under aerobic conditions, low temperature severely limited PAH biodegradation. After 90 days, aerobic cultures at 20°C removed 52 to 88% of the PAHs. The most extensive PAH degradation under aerobic conditions at 7°C, 53% removal, occurred in a culture from creosote-contaminated soil. Low temperature did not substantially limit PAH biodegradation under nitrate-reducing conditions. Under nitrate-reducing conditions, naphthalene, 2-methylnaphthalene, fluorene, and phenanthrene were degraded. The most extensive PAH degradation under nitrate-reducing conditions at 7°C, 39% removal, occurred in a culture from fuel-contaminated Arctic soil. In separate transfer cultures from the above Arctic soil, incubated anaerobically at 7°C, removal of 2-methylnaphthalene and fluorene was stoichiometrically coupled to nitrate removal. Ribosomal intergenic spacer analysis suggested that enrichment resulted in a few predominant bacterial populations, including members of the genera Acidovorax, Bordetella, Pseudomonas, Sphingomonas, and Variovorax. Predominant populations from different soils often included phylotypes with nearly identical partial 16S rRNA gene sequences (i.e., same genus) but never included phylotypes with identical ribosomal intergenic spacers (i.e., different species or subspecies). The composition of the enriched communities appeared to be more affected by presence of oxygen, than by temperature or source of the inoculum. PMID:12514005

  2. Eutectic growth under acoustic levitation conditions

    NASA Astrophysics Data System (ADS)

    Xie, W. J.; Cao, C. D.; Lü, Y. J.; Wei, B.

    2002-12-01

    Samples of Pb-Sn eutectic alloy with a high density of 8.5×103 kg/m3 are levitated with a single-axis acoustic levitator, and containerlessly melted and then solidified in argon atmosphere. High undercoolings up to 38 K are obtained, which results in a microstructural transition of ``lamellas-broken lamellas-dendrites.'' This transition is further investigated in the light of the coupled zone for eutectic growth and the effects of ultrasound. The breaking of regular eutectic lamellas and suppression of gravity-induced macrosegregation of (Pb) and (Sn) dendrites are explained by the complicated internal flow inside the levitated drop, which is jointly induced by the shape oscillation, bulk vibration and rotation of the levitated drop. The ultrasonic field is also found to drive forced surface vibration, which subsequently excites capillary ripples and catalyzes nucleation on the sample surface.

  3. Eutectic growth under acoustic levitation conditions.

    PubMed

    Xie, W J; Cao, C D; Lü, Y J; Wei, B

    2002-12-01

    Samples of Pb-Sn eutectic alloy with a high density of 8.5 x 10(3) kg/m(3) are levitated with a single-axis acoustic levitator, and containerlessly melted and then solidified in argon atmosphere. High undercoolings up to 38 K are obtained, which results in a microstructural transition of "lamellas-broken lamellas-dendrites." This transition is further investigated in the light of the coupled zone for eutectic growth and the effects of ultrasound. The breaking of regular eutectic lamellas and suppression of gravity-induced macrosegregation of (Pb) and (Sn) dendrites are explained by the complicated internal flow inside the levitated drop, which is jointly induced by the shape oscillation, bulk vibration and rotation of the levitated drop. The ultrasonic field is also found to drive forced surface vibration, which subsequently excites capillary ripples and catalyzes nucleation on the sample surface. PMID:12513291

  4. Quantification of aerobic biodegradation and volatilization rates of gasoline hydrocarbons near the water table under natural attenuation conditions

    USGS Publications Warehouse

    Lahvis, M.A.; Baehr, A.L.; Baker, R.J.

    1999-01-01

    Aerobic biodegradation and volatilization near the water table constitute a coupled pathway that contributes significantly to the natural attenuation of hydrocarbons at gasoline spill sites. Rates of hydrocarbon biodegradation and volatilization were quantified by analyzing vapor transport in the unsaturated zone at a gasoline spill site in Beaufort, South Carolina. Aerobic biodegradation rates decreased with distance above the water table, ranging from 0.20 to 1.5g m-3 d-1 for toluene, from 0.24 to 0.38 g m-3 d-1 for xylene, from 0.09 to 0.24 g m-3 d-1 for cyclohexene, from 0.05 to 0.22 g m-3 d-1 for ethylbenzene, and from 0.02 to 0.08 g m-3 d-1 for benzene. Rates were highest in the capillary zone, where 68% of the total hydrocarbon mass that volatilized from the water table was estimated to have been biodegraded. Hydrocarbons were nearly completely degraded within 1 m above the water table. This large loss underscores the importance of aerobic biodegradation in limiting the transport of hydrocarbon vapors in the unsaturated zone and implies that vapor-plume migration to basements and other points of contact may only be significant if a source of free product is present. Furthermore, because transport of the hydrocarbon in the unsaturated zone can be limited relative to that of oxygen and carbon dioxide, soil, gas surveys conducted at hydrocarbon-spill sites would benefit by the inclusion of oxygen- and carbon-dioxide-gas concentration measurements. Aerobic degradation kinetics in the unsaturated zone were approximately first-order. First-order rate constants near the water table were highest for cyctohexene (0.21-0.65 d-1) and nearly equivalent for ethylbenzene (0.11-20.31 d-1), xylenes (0.10-0.31 d-1), toluene (0.09-0.30 d-1), and benzene (0.07,0.31 d-1). Hydrocarbon mass loss rates at the water table resulting from the coupled aerobic biodegradation and volatilization process were determined by extrapolating gas transport rates through the capillary zone. Mass

  5. Influence of mechanical disintegration on the microbial growth of aerobic sludge biomass: A comparative study of ultrasonic and shear gap homogenizers by oxygen uptake measurements.

    PubMed

    Divyalakshmi, P; Murugan, D; Sivarajan, M; Saravanan, P; Lajapathi Rai, C

    2015-11-01

    Wastewater treatment plant incorporates physical, chemical and biological processes to treat and remove the contaminants. The main drawback of conventional activated sludge process is the huge production of excess sludge, which is an unavoidable byproduct. The treatment and disposal of excess sludge costs about 60% of the total operating cost. The ideal way to reduce excess sludge production during wastewater treatment is by preventing biomass formation within the aerobic treatment train rather than post treatment of the generated sludge. In the present investigation two different mechanical devices namely, Ultrasonic and Shear Gap homogenizers have been employed to disintegrate the aerobic biomass. This study is intended to restrict the multiplication of microbial biomass and at the same time degrade the organics present in wastewater by increasing the oxidative capacity of microorganisms. The disintegrability on biomass was determined by biochemical methods. Degree of inactivation provides the information on inability of microorganisms to consume oxygen upon disruption. The soluble COD quantifies the extent of release of intra cellular compounds. The participation of disintegrated microorganism in wastewater treatment process was carried out in two identical respirometeric reactors. The results show that Ultrasonic homogenizer is very effective in the disruption of microorganisms leading to a maximum microbial growth reduction of 27%. On the other hand, Shear gap homogenizer does not favor the sludge growth reduction rather it facilitates the growth. This study also shows that for better microbial growth reduction, floc size reduction alone is not sufficient but also microbial disruption is essential. PMID:25866205

  6. Recovery of Nickel and Cobalt from Laterite Tailings by Reductive Dissolution under Aerobic Conditions Using Acidithiobacillus Species.

    PubMed

    Marrero, J; Coto, O; Goldmann, S; Graupner, T; Schippers, A

    2015-06-01

    Biomining of sulfidic ores has been applied for almost five decades. However, the bioprocessing of oxide ores such as laterites lags commercially behind. Recently, the Ferredox process was proposed to treat limonitic laterite ores by means of anaerobic reductive dissolution (AnRD), which was found to be more effective than aerobic bioleaching by fungi and other bacteria. We show here that the ferric iron reduction mediated by Acidithiobacillus thiooxidans can be applied to an aerobic reductive dissolution (AeRD) of nickel laterite tailings. AeRD using a consortium of Acidithiobacillus thiooxidans and Acidithiobacillus ferrooxidans extracted similar amounts of nickel (53-57%) and cobalt (55-60%) in only 7 days as AnRD using Acidithiobacillus ferrooxidans. The economic and environmental advantages of AeRD for processing of laterite tailings comprise no requirement for an anoxic atmosphere, 1.8-fold less acid consumption than for AnRD, as well as nickel and cobalt recovered in a ferrous-based pregnant leach solution (PLS), facilitating the subsequent metal recovery. In addition, an aerobic acid regeneration stage is proposed. Therefore, AeRD process development can be considered as environmentally friendly for treating laterites with low operational costs and as an attractive alternative to AnRD. PMID:25923144

  7. Delayed formation of zero-valent selenium nanoparticles by Bacillus mycoides SeITE01 as a consequence of selenite reduction under aerobic conditions

    PubMed Central

    2014-01-01

    Background Selenite (SeO32−) oxyanion shows severe toxicity to biota. Different bacterial strains exist that are capable of reducing SeO32− to non-toxic elemental selenium (Se0), with the formation of Se nanoparticles (SeNPs). These SeNPs might be exploited for technological applications due to their physico-chemical and biological characteristics. The present paper discusses the reduction of selenite to SeNPs by a strain of Bacillus sp., SeITE01, isolated from the rhizosphere of the Se-hyperaccumulator legume Astragalus bisulcatus. Results Use of 16S rRNA and GyrB gene sequence analysis positioned SeITE01 phylogenetically close to B. mycoides. On agarized medium, this strain showed rhizoid growth whilst, in liquid cultures, it was capable of reducing 0.5 and 2.0 mM SeO32− within 12 and 24 hours, respectively. The resultant Se0 aggregated to form nanoparticles and the amount of Se0 measured was equivalent to the amount of selenium originally added as selenite to the growth medium. A delay of more than 24 hours was observed between the depletion of SeO32 and the detection of SeNPs. Nearly spherical-shaped SeNPs were mostly found in the extracellular environment whilst rarely in the cytoplasmic compartment. Size of SeNPs ranged from 50 to 400 nm in diameter, with dimensions greatly influenced by the incubation times. Different SeITE01 protein fractions were assayed for SeO32− reductase capability, revealing that enzymatic activity was mainly associated with the membrane fraction. Reduction of SeO32− was also detected in the supernatant of bacterial cultures upon NADH addition. Conclusions The selenite reducing bacterial strain SeITE01 was attributed to the species Bacillus mycoides on the basis of phenotypic and molecular traits. Under aerobic conditions, the formation of SeNPs were observed both extracellularly or intracellullarly. Possible mechanisms of Se0 precipitation and SeNPs assembly are suggested. SeO32− is proposed to be enzimatically reduced to

  8. Die another day: Fate of heat-treated Geobacillus stearothermophilus ATCC 12980 spores during storage under growth-preventing conditions.

    PubMed

    Mtimet, Narjes; Trunet, Clément; Mathot, Anne-Gabrielle; Venaille, Laurent; Leguérinel, Ivan; Coroller, Louis; Couvert, Olivier

    2016-06-01

    Geobacillus stearothermophilus spores are recognized as one of the most wet-heat resistant among aerobic spore-forming bacteria and are responsible for 35% of canned food spoilage after incubation at 55 °C. The purpose of this study was to investigate and model the fate of heat-treated survivor spores of G. stearothermophilus ATCC 12980 in growth-preventing environment. G. stearothermophilus spores were heat-treated at four different conditions to reach one or two decimal reductions. Heat-treated spores were stored in nutrient broth at different temperatures and pH under growth-preventing conditions. Spore survival during storage was evaluated by count plating over a period of months. Results reveal that G. stearothermophilus spores surviving heat treatment lose their viability during storage under growth-preventing conditions. Two different subpopulations were observed during non-thermal inactivation. They differed according to the level of their resistance to storage stress, and the proportion of each subpopulation can be modulated by heat treatment conditions. Finally, tolerance to storage stress under growth-preventing conditions increases at refrigerated temperature and neutral pH regardless of heat treatment conditions. Such results suggest that spore inactivation due to heat treatment could be completed by storage under growth-preventing conditions. PMID:26919821

  9. Aerobic growth of campylobacter in media supplemented with a-ketoglutaric, lactic, and/or fumaric acids

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A study was conducted to examine the ability of Campylobacter spp. to grow aerobically in media supplemented with selected organic acids. Basal broth media composed of tryptose, yeast extract, and a mineral-vitamin solution was supplemented with a-ketoglutaric, lactic, and/or fumaric acids. The fina...

  10. Response of aerobic rice to Piriformospora indica.

    PubMed

    Das, Joy; Ramesh, K V; Maithri, U; Mutangana, D; Suresh, C K

    2014-03-01

    Rice cultivation under aerobic condition not only saves water but also opens up a splendid scope for effective application of beneficial root symbionts in rice crop unlike conventional puddled rice cultivation where water logged condition acts as constraint for easy proliferation of various beneficial soil microorganisms like arbuscular mycorrhizal (AM) fungi. Keeping these in view, an in silico investigation were carried out to explore the interaction of hydrogen phosphate with phosphate transporter protein (PTP) from P. indica. This was followed by greenhouse investigation to study the response of aerobic rice to Glomusfasciculatum, a conventional P biofertilizer and P. indica, an alternative to AM fungi. Computational studies using ClustalW tool revealed several conserved motifs between the phosphate transporters from Piriformospora indica and 8 other Glomus species. The 3D model of PTP from P. indica resembling "Mayan temple" was successfully docked onto hydrogen phosphate, indicating the affinity of this protein for inorganic phosphorus. Greenhouse studies revealed inoculation of aerobic rice either with P. indica, G. fasciculatum or both significantly enhanced the plant growth, biomass and yield with higher NPK, chlorophyll and sugar compared to uninoculated ones, P. indica inoculated plants being superior. A significantly enhanced activity of acid phosphatase and alkaline phosphatase were noticed in the rhizosphere soil of rice plants inoculated either with P. indica, G. fasciculatum or both, contributing to higher P uptake. Further, inoculation of aerobic rice plants with P. indica proved to be a better choice as a potential biofertilizer over mycorrhiza. PMID:24669667

  11. Effect of boundary conditions on thermal plume growth

    NASA Astrophysics Data System (ADS)

    Kondrashov, A.; Sboev, I.; Rybkin, K.

    2016-07-01

    We have investigated the influence of boundary conditions on the growth rate of convective plumes. Temperature and rate fields were studied in a rectangular convective cell heated by a spot heater. The results of the full-scale test were compared with the numerical data calculated using the ANSYS CFX software package. The relationship between the heat plume growth rate and heat boundary conditions, the width and height of the cell, size of heater for different kinds of liquid was established.

  12. Effect of short-time aerobic digestion on bioflocculation of extracellular polymeric substances from waste activated sludge.

    PubMed

    Zhang, Zhiqiang; Zhang, Jiao; Zhao, Jianfu; Xia, Siqing

    2015-02-01

    The effect of short-time aerobic digestion on bioflocculation of extracellular polymeric substances (EPSs) from waste activated sludge (WAS) was investigated. Bioflocculation of the EPS was found to be enhanced by 2∼6 h of WAS aerobic digestion under the conditions of natural sludge pH (about 7), high sludge concentration by gravity thickening, and dissolved oxygen of about 2 mg/L. With the same EPS extraction method, the total suspended solid content reduction of 0.20 and 0.36 g/L and the volatile suspended solid content reduction of 0.19 and 0.26 g/L were found for the WAS samples before and after aerobic digestion of 4 h. It indicates that more EPS is produced by short-time aerobic digestion of WAS. The scanning electron microscopy images of the WAS samples before and after aerobic digestion of 4 h showed that more EPS appeared on the surface of zoogloea by aerobic digestion, which reconfirmed that WAS aerobic digestion induced abundant formation of EPS. By WAS aerobic digestion, the flocculating rate of the EPS showed about 31 % growth, almost consistent with the growth of its yield (about 34 %). The EPSs obtained before and after the aerobic digestion presented nearly the same components, structures, and Fourier transform infrared spectra. These results revealed that short-time aerobic digestion of WAS enhanced the flocculation of the EPS by promoting its production. PMID:23771440

  13. Growth parameters of Escherichia coli O157:H7, Salmonella spp., Listeria monocytogenes, and aerobic mesophilic bacteria of apple cider amended with nisin-EDTA.

    PubMed

    Ukuku, Dike O; Zhang, Howard; Huang, Lihan

    2009-05-01

    The effect of nisin (0 or 300 IU/mL), ethylenediamine tetraacetic acid (EDTA, 20 mM), and nisin (300 IU)-EDTA (20 mM) on growth parameters, including lag period (LP) and generation time, of Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella spp. in the presence or absence of aerobic mesophilic bacteria of apple cider during storage at 5 degrees C for up to 16 days or 23 degrees C for 16 h was investigated. The growth data were analyzed and fitted to the modified Gompertz model. The LP values for aerobic mesophilic bacteria of apple cider (control) and those amended with EDTA and nisin during storage at 5 degrees C were 1.61, 1.76, and 5.45 days, respectively. In apple cider stored at 23 degrees C for 16 h, the LP values for the same bacteria and treatment were 3.24, 3.56, and 5.85 h, respectively. The LP values for E. coli O157:H7 determined in the presence of aerobic mesophilic bacteria of apple cider stored at 23 degrees C for 16 h was 1.48 h, while populations for L. monocytogenes and Salmonella in the same cider declined. In sterile apple cider left at 23 degrees C for 16 h, the LP values for E. coli O157:H7, Salmonella, and L. monocytogenes averaged 2.74, 2.37, and 3.16 h, respectively. The generation time for these pathogens were 0.402, 0.260, and 0.187 log (CFU/mL)/h, respectively. Addition of nisin and EDTA combination caused a decline in lag phase duration and the populations for all pathogens tested, suggesting possible addition of this additive to freshly prepared apple cider to enhance its microbial safety and prevent costly recalls. PMID:19415973

  14. Isolation and characterization of ubiquinol oxidase complexes from Paracoccus denitrificans cells cultured under various limiting growth conditions in the chemostat.

    PubMed

    Bosma, G; Braster, M; Stouthamer, A H; van Verseveld, H W

    1987-06-15

    To obtain more information about the composition of the respiratory chain under different growth conditions and about the regulation of electron-transfer to several oxidases and reductases, ubiquinol oxidase complexes were partially purified from membranes of Paracoccus denitrificans cells grown in carbon-source-limited aerobic, nitrate-limited anaerobic and oxygen-limited chemostat cultures. The isolated enzymes consisted of cytochromes bc1, c552 and aa3. In comparison with the aerobic ubiquinol oxidase complex, the oxygen- and nitrate-limited ones contained, respectively, less and far less of the cytochrome aa3 subunits and the anaerobic complex also contained lower amounts of cytochrome c552. In addition, extra haem-containing polypeptides were present with apparent Mr of 14,000, 30,000 and 45,000, the former one only in the anaerobic and the latter two in both the anaerobic and oxygen-limited preparations. This is the first report describing four different membrane-bound c-type cytochromes. The potentiometric and spectral characteristics of the redox components in membrane particles and isolated ubiquinol oxidase fractions were determined by combined potentiometric analysis and spectrum deconvolution. Membranes of nitrate- and oxygen-limited cells contained extra high-potential cytochrome b in comparison with the membranes of aerobically grown cells. No difference was detected between the three isolated ubiquinol oxidase complexes. Aberrances with already published values of redox potentials are discussed. PMID:3036512

  15. Ice Crystal Growth Rates Under Upper Troposphere Conditions

    NASA Technical Reports Server (NTRS)

    Peterson, Harold S.; Bailey, Matthew; Hallett, John

    2010-01-01

    Atmospheric conditions for growth of ice crystals (temperature and ice supersaturation) are often not well constrained and it is necessary to simulate such conditions in the laboratory to investigate such growth under well controlled conditions over many hours. The growth of ice crystals from the vapour in both prism and basal planes was observed at temperatures of -60 C and -70 C under ice supersaturation up to 100% (200% relative humidity) at pressures derived from the standard atmosphere in a static diffusion chamber. Crystals grew outward from a vertical glass filament, thickening in the basal plane by addition of macroscopic layers greater than 2 m, leading to growth in the prism plane by passing of successive layers conveniently viewed by time lapse video.

  16. Ice Particle Growth Under Conditions of the Upper Troposphere

    NASA Technical Reports Server (NTRS)

    Peterson, Harold S.; Bailey, Matthew; Hallett, John

    2010-01-01

    Atmospheric conditions for growth of ice crystals (temperature and ice supersaturation) are often not well constrained and it is necessary to simulate such conditions in the laboratory to investigate such growth under well controlled conditions over many hours. The growth of ice crystals from the vapour in both prism and basal planes was observed at temperatures of -60 C and -70 C under ice supersaturation up to 100% (200% relative humidity) at pressures derived from the standard atmosphere in a static diffusion chamber. Crystals grew outward from a vertical glass filament, thickening in the basal plane by addition of macroscopic layers greater than 2 microns, leading to growth in the prism plane by passing of successive layers conveniently viewed by time lapse video.

  17. Ice Particle Growth Rates Under Upper Troposphere Conditions

    NASA Technical Reports Server (NTRS)

    Peterson, Harold; Bailey, Matthew; Hallett, John

    2010-01-01

    Atmospheric conditions for growth of ice crystals (temperature and ice supersaturation) are often not well constrained and it is necessary to simulate such conditions in the laboratory to investigate such growth under well controlled conditions over many hours. The growth of ice crystals from the vapour in both prism and basal planes was observed at temperatures of -60 C and -70 C under ice supersaturation up to 100% (200% relative humidity) at pressures derived from the standard atmosphere in a static diffusion chamber. Crystals grew outward from a vertical glass filament, thickening in the basal plane by addition of macroscopic layers greater than 2 m, leading to growth in the prism plane by passing of successive layers conveniently viewed by time lapse video.

  18. Influence of food colorant and initial COD concentration on the efficiencies of micro-aerobic sequencing batch reactor (micro-aerobic SBR) for casein recovery under non-sterile condition by Lactobacillus casei TISTR 1500.

    PubMed

    Seesuriyachan, Phisit; Chaiyaso, Thanongsak; Sasaki, Ken; Techapun, Charin

    2009-09-01

    The acid biocoagulants produced from non-sterile lactic acid fermentation by Lactobacillus casei TISTR 1500 were used to settle colloidal protein, mainly casein, at the isoelectric point in dairy effluent prior to secondary treatment. High concentration of azo dye (Ponceau 4R) in the dairy wastewater and the stress of starvation decreased the efficiencies of the micro-aerobic SBR. Consequently, low casein recovery obtained and organic removal suffered a decline. The number of lactic acid bacteria (LAB) also declined from log 7.4 to log 5.30 in the system fed with 400 mg L(-1) of the dye containing wastewater. The recovery of the system, however, showed that 25,000 mg COD L(-1) influent with 200 mg L(-1) of the dye maintained the growth of LAB in the range of log 7.74-8.12, with lactic and acetic production (2597 and 197 mg L(-1)) and 83% protein removal. The results in this study suggested that the inhibitory effects were compensated with high organic content feeding. PMID:19423333

  19. Growth of Campylobacter incubated aerobically in fumarate-pyruvate media or media supplemented with dairy, meat, or soy extracts and peptones.

    PubMed

    Hinton, Arthur

    2016-09-01

    The ability of Campylobacter to grow aerobically in media supplemented with fumarate-pyruvate or with dairy, meat, or soy extracts or peptones was examined. Optical densities (OD) of Campylobacter cultured in basal media, media supplemented with fumarate-pyruvate or with 1.0, 2.5, 5.0, or 7.5% beef extract was measured. Growth was also compared in media supplemented with other extracts or peptones. Finally, cfu/mL of Campylobacter recovered from basal media or media supplemented with fumarate-pyruvate, casamino acids, beef extract, soytone, or beef extract and soytone was determined. Results indicated that OD of cultures grown in media supplemented with fumarate-pyruvate or with 5.0 or 7.5% beef extract were higher than OD of isolates grown in basal media or media supplemented with lower concentrations of beef extract. Highest OD were produced by isolates grown in media supplemented with beef extract, peptone from meat, polypeptone, proteose peptone, or soytone. Also, more cfu/mL were recovered from media with fumarate-pyruvate, beef extract, soytone, or beef extract-soytone than from basal media or media with casamino acids. Findings indicate that media supplemented with organic acids, vitamins, and minerals and media supplemented with extracts or peptones containing these metabolites can support aerobic growth of Campylobacter. PMID:27217355

  20. [NiFe]-hydrogenase is essential for cyanobacterium Synechocystis sp. PCC 6803 aerobic growth in the dark

    PubMed Central

    De Rosa, Edith; Checchetto, Vanessa; Franchin, Cinzia; Bergantino, Elisabetta; Berto, Paola; Szabò, Ildikò; Giacometti, Giorgio M.; Arrigoni, Giorgio; Costantini, Paola

    2015-01-01

    The cyanobacterium Synechocystis sp. PCC 6803 has a bidirectional [NiFe]-hydrogenase (Hox hydrogenase) which reversibly reduces protons to H2. This enzyme is composed of a hydrogenase domain and a diaphorase moiety, which is distinctly homologous to the NADH input module of mitochondrial respiratory Complex I. Hox hydrogenase physiological function is still unclear, since it is not required for Synechocystis fitness under standard growth conditions. We analyzed the phenotype under prolonged darkness of three Synechocystis knock-out strains, lacking either Hox hydrogenase (ΔHoxE-H) or one of the proteins responsible for the assembly of its NiFe active site (ΔHypA1 and ΔHypB1). We found that Hox hydrogenase is required for Synechocystis growth under this condition, regardless of the functional status of its catalytic site, suggesting an additional role beside hydrogen metabolism. Moreover, quantitative proteomic analyses revealed that the expression levels of several subunits of the respiratory NADPH/plastoquinone oxidoreductase (NDH-1) are reduced when Synechocystis is grown in the dark. Our findings suggest that the Hox hydrogenase could contribute to electron transport regulation when both photosynthetic and respiratory pathways are down-regulated, and provide a possible explanation for the close evolutionary relationship between mitochondrial respiratory Complex I and cyanobacterial [NiFe]-hydrogenases. PMID:26215212

  1. Indium antimonide crystal growth experiment M562. [Skylab weightless conditions

    NASA Technical Reports Server (NTRS)

    Gatos, H. C.; Witt, A. F.

    1974-01-01

    It was established that ideal diffusion controlled steady state conditions, never accomplished on earth, were achieved during the growth of Te-doped InSb crystals in Skylab. Surface tension effects led to nonwetting conditions under which free surface solidification took place in confined geometry. It was further found that, under forced contact conditions, surface tension effects led to the formation of surface ridges (not previously observed on earth) which isolated the growth system from its container. In addition, it was possible, for the first time, to identify unambiguously: the origin of segregation discontinuities associated with facet growth, the mode of nucleation and propagation of rotational twin boundaries, and the specific effect of mechanical-shock perturbations on segregation. The results obtained prove the advantageous conditions provided by outer space. Thus, fundamental data on solidification thought to be unattainable because of gravity-induced interference on earth are now within reach.

  2. A novel nucleoid protein of Escherichia coli induced under anaerobiotic growth conditions.

    PubMed

    Teramoto, Jun; Yoshimura, Shige H; Takeyasu, Kunio; Ishihama, Akira

    2010-06-01

    A systematic search was performed for DNA-binding sequences of YgiP, an uncharacterized transcription factor of Escherichia coli, by using the Genomic SELEX. A total of 688 YgiP-binding loci were identified after genome-wide profiling of SELEX fragments with a high-density microarray (SELEX-chip). Gel shift and DNase-I footprinting assays indicated that YgiP binds to multiple sites along DNA probes with a consensus GTTNATT sequence. Atomic force microscope observation indicated that at low concentrations, YgiP associates at various sites on DNA probes, but at high concentrations, YgiP covers the entire DNA surface supposedly through protein-protein contact. The intracellular concentration of YgiP is very low in growing E. coli cells under aerobic conditions, but increases more than 100-fold to the level as high as the major nucleoid proteins under anaerobic conditions. An E. coli mutant lacking ygiP showed retarded growth under anaerobic conditions. High abundance and large number of binding sites together indicate that YgiP is a nucleoid-associated protein with both architectural and regulatory roles as the nucleoid proteins Fis and IHF. We then propose that YgiP is a novel nucleoid protein of E. coli under anaerobiosis and propose to rename it Dan (DNA-binding protein under anaerobic conditions). PMID:20156994

  3. Activated sludge mass reduction and biodegradability of the endogenous residues by digestion under different aerobic to anaerobic conditions: Comparison and modeling.

    PubMed

    Martínez-García, C G; Fall, C; Olguín, M T

    2016-03-01

    This study was performed to identify suitable conditions for the in-situ reduction of excess sludge production by intercalated digesters in recycle-activated sludge (RAS) flow. The objective was to compare and model biological sludge mass reduction and the biodegradation of endogenous residues (XP) by digestion under hypoxic, aerobic, anaerobic, and five intermittent-aeration conditions. A mathematical model based on the heterotrophic endogenous decay constant (bH) and including the biodegradation of XP was used to fit the long-term data from the digesters to identify and estimate the parameters. Both the bH constant (0.02-0.05 d(-1)) and the endogenous residue biodegradation constant (bP, 0.001-0.004 d(-1)) were determined across the different mediums. The digesters with intermittent aeration cycles of 12 h-12 h and 5 min-3 h (ON/OFF) were the fastest, compared to the aerobic reactor. The study provides a basis for rating RAS-digester volumes to avoid the accumulation of XP in aeration tanks. PMID:26720137

  4. The determination of the real nano-scale sizes of bacteria in chernozem during microbial succession by means of hatching of a soil in aerobic and anaerobic conditions

    NASA Astrophysics Data System (ADS)

    Gorbacheva, M.

    2012-04-01

    M.A. Gorbacheva,L.M. Polyanskaya The Faculty of Soil Science, Moscow State University, Leninskie Gory, GSP-1, Moscow,119991,Russia In recent years there's been particular attention paid to the smallest life's forms- bacteria which size can be measured in nanometer. These are the forms of bacteria with diameter of 5-200 nm. Theoretical calculations based on the content of the minimum number of DNA, enzyme, lipids in and ribosome in cells indicates impossibility of existence of a living cells within diameter less than 300 nm. It is theoretically possible for a living cell to exist within possible diameter of approximately 140 nm. Using a fluorescence microscope there's been indicated in a number of samples from lakes, rivers, soil, snow and rain water that 200 nm is the smallest diameter of a living cell. Supposingly, such a small size of bacteria in soil is determined by natural conditions which limit their development by nutritious substances and stress-factors. Rejuvenescence of nanobacteria under unfavourable natural conditions and stress-factors is studied in laboratory environment. The object of the current study has become the samples of typical arable chernozem of the Central Chernozem State Biosphere Reserve in Kursk. The detailed morphological description of the soil profile and its basic analytical characteristics are widely represented in scientific publications. The soil is characterized by a high carbon content which makes up 3,96% ,3,8% , and 2,9% for the upper layers of the A horizon, and 0,79% for the layer of the B horizon. A microbial succession was studied under aerobic and anaerobic conditions by means of experiments with microcosms in upper A horizons and B horizon of a chernozem. The final aim is to identify the cells size of bacteria in aerobic and anaerobic soil conditions in chernozem during the microbial succession, by dampening and application of chitin by means of «cascade filtration» method. The study of the microcosms is important for

  5. Denitrification characteristics of a marine origin psychrophilic aerobic denitrifying bacterium.

    PubMed

    Zheng, Haiyan; Liu, Ying; Sun, Guangdong; Gao, Xiyan; Zhang, Qingling; Liu, Zhipei

    2011-01-01

    A psychrophilic aerobic denitrifying bacterium, strain S1-1, was isolated from a biological aerated filter conducted for treatment of recirculating water in a marine aquaculture system. Strain S1-1 was preliminarily identified as Psychrobacter sp. based on the analysis of its 16S rRNA gene sequence, which showed 100% sequence similarity to that of Psychrobacter sp. TSBY-70. Strain S1-1 grew well either in high nitrate or high nitrite conditions with a removal of 100% nitrate or 63.50% nitrite, and the total nitrogen removal rates could reach to 46.48% and 31.89%, respectively. The results indicated that nitrate was mainly reduced in its logarithmic growth phase with a very low level accumulation of nitrite, suggesting that the aerobic denitrification process of strain S1-1 occurred mainly in this phase. The GC-MS results showed that N2O was formed as the major intermediate during the aerobic denitrifying process of strain S1-1. Finally, factors affecting the growth of strain S1-1 and its aerobic denitrifying ability were also investigated. Results showed that the optimum aerobic denitrification conditions for strain S1-1 were sodium succinate as carbon source, C/N ratio15, salinity 10 g/L NaCl, incubation temperature 20 degrees C and initial pH 6.5. PMID:22432315

  6. Optimal Culture Conditions for Mycelial Growth of Lignosus rhinocerus

    PubMed Central

    Siti Murni, M.J.; Fauzi, D.; Abas Mazni, O.; Saleh, N.M.

    2011-01-01

    Lignosus rhinocerus is a macrofungus that belongs to Polyporaceae and is native to tropical regions. This highly priced mushroom has been used as folk medicine to treat diseases by indigenous people. As a preliminary study to develop a culture method for edible mushrooms, the cultural characteristics of L. rhinocerus were investigated in a range of culture media under different environmental conditions. Mycelial growth of this mushroom was compared on culture media composed of various carbon and nitrogen sources in addition to C/N ratios. The optimal conditions for mycelial growth were 30℃ at pH 6 and 7. Rapid mycelial growth of L. rhinocerus was observed on glucose-peptone and yeast extract peptone dextrose media. Carbon and nitrogen sources promoting mycelial growth of L. rhinocerus were glucose and potassium nitrate, respectively. The optimum C/N ratio was approximately 10 : 1 using 2% glucose supplemented as a carbon source in the basal media. PMID:22783083

  7. Crystal growth of a binary compound semiconductor under microgravity conditions

    NASA Astrophysics Data System (ADS)

    Hiraoka, Y.; Ikegami, K.; Maekawa, T.; Matsumoto, S.; Yoda, S.; Kinoshita, K.

    We investigate the possibilities of growing a uniform binary compound crystal in space numerically, proposing a new crystal growth method. We develop a numerical calculation method of the growth of binary crystals. The calculation method is applied to the crystal growth analysis of an InAs-GaAs binary semiconductor and the effect of buoyancy convection induced under microgravity conditions on the crystal growth process is investigated. We find that the concentration field is disturbed and, as a result, the solution—crystal interface is deformed by buoyancy convection even when the gravitational acceleration is as low as 10 -6 g, which is supposed to be the gravity level in the International Space Station. We also find that the direction of residual gravity has a strong effect on the concentration field in the solution and the crystal growth process.

  8. Changes in alpine plant growth under future climate conditions

    NASA Astrophysics Data System (ADS)

    Rammig, A.; Jonas, T.; Zimmermann, N. E.; Rixen, C.

    2010-06-01

    Alpine shrub- and grasslands are shaped by extreme climatic conditions such as a long-lasting snow cover and a short vegetation period. Such ecosystems are expected to be highly sensitive to global environmental change. Prolonged growing seasons and shifts in temperature and precipitation are likely to affect plant phenology and growth. In a unique experiment, climatology and plant growth was monitored for almost a decade at 17 snow meteorological stations in different alpine regions along the Swiss Alps. Regression analyses revealed highly significant correlations between mean air temperature in May/June and snow melt out, onset of plant growth, and plant height. These correlations were used to project plant growth phenology for future climate conditions based on the gridded output of a set of regional climate models runs. Melt out and onset of growth were projected to occur on average 17 days earlier by the end of the century than in the control period from 1971-2000 under the future climate conditions of the low resolution climate model ensemble. Plant height and biomass production were expected to increase by 77% and 45%, respectively. The earlier melt out and onset of growth will probably cause a considerable shift towards higher growing plants and thus increased biomass. Our results represent the first quantitative and spatially explicit estimates of climate change impacts on future growing season length and the respective productivity of alpine plant communities in the Swiss Alps.

  9. Changes in alpine plant growth under future climate conditions

    NASA Astrophysics Data System (ADS)

    Rammig, A.; Jonas, T.; Zimmermann, N. E.; Rixen, C.

    2009-11-01

    Alpine shrub- and grasslands are shaped by extreme climatic conditions such as a long-lasting snow cover and a short vegetation period. Such ecosystems are expected to be highly sensitive to global environmental change. Prolonged growing seasons and shifts in temperature and precipitation are likely to affect plant phenology and growth. In a unique experiment, climatology and plant growth was monitored for almost a decade at 17 snow meteorological stations in different alpine regions along the Swiss Alps. Regression analyses revealed highly significant correlations between mean air temperature in May/June and snow melt-out, onset of plant growth, and plant height. These correlations were used to project plant growth phenology for future climate conditions based on the gridded output of a set of regional climate models runs. Melt-out and onset of growth were projected to occur on average 17 days earlier by the end of the century than in the control period from 1971-2000 under the future climate conditions of the low resolution climate model ensemble. Plant height and biomass production were expected to increase by 77% and 45%, respectively. The earlier melt-out and onset of growth will probably cause a considerable shift towards higher growing plants and thus increased biomass. Our results represent the first quantitative and spatially explicit estimates of climate change impacts on future growing season length and the respective productivity of alpine plant communities in the Swiss Alps.

  10. Characterization of aerobic ethanol productions in a computerized auxostat

    SciTech Connect

    Fraleigh, S.P.

    1989-01-01

    For many valuable bioproducts high productivity is associated with rapid growth. However, most continuous microbial cultures become unstable when the dilution rate is fixed near the value for maximum growth rate. The auxostat culture technique employs feedback control of a nutrient or metabolite to stabilize the biomass at its maximum potential growth rate. An auxostat device is therefore ideal for study of bioprocesses involving the overproduction of primary metabolites such as ethanol. Oxidoreductive transformations involving ethanol are utilized by Saccharomyces yeasts when normal respiration cannot satisfy energy needs. When rapid growth or other stress creates oxidoreductive conditions in aerobic Saccharomyces cultures, very high specific ethanol formation rates are established and biomass yield drops to levels more typical of anaerobic fermentation. Although the physiology is favorable, the potential for large-scale aerobic ethanol processes to compete with traditional anaerobic fermentations has not previously been assessed. In this study, a fully computerized auxostat device was constructed and used to characterize the specific and volumetric aerobic ethanol productivity of the yeast Saccharomyces cerevisiae. To divert substrate away from biomass and into product formation, aerobic cultures were stressed with variations of ionic balance (via extreme K{sup +} and H{sup +} setpoints) in the auxostat device. During growth with limiting K{sup +} concentrations, the goal of very low biomass yield was attained but the rate of ethanol production was poor. However, with excess K{sup +} the volumetric productivity reached 6.1 g/I,-h, a value that is comparable to optimized, continuous anaerobic cultures.

  11. Carnitine palmitoyltransferase 1C promotes cell survival and tumor growth under conditions of metabolic stress.

    PubMed

    Zaugg, Kathrin; Yao, Yi; Reilly, Patrick T; Kannan, Karuppiah; Kiarash, Reza; Mason, Jacqueline; Huang, Ping; Sawyer, Suzanne K; Fuerth, Benjamin; Faubert, Brandon; Kalliomäki, Tuula; Elia, Andrew; Luo, Xunyi; Nadeem, Vincent; Bungard, David; Yalavarthi, Sireesha; Growney, Joseph D; Wakeham, Andrew; Moolani, Yasmin; Silvester, Jennifer; Ten, Annick You; Bakker, Walbert; Tsuchihara, Katsuya; Berger, Shelley L; Hill, Richard P; Jones, Russell G; Tsao, Ming; Robinson, Murray O; Thompson, Craig B; Pan, Guohua; Mak, Tak W

    2011-05-15

    Tumor cells gain a survival/growth advantage by adapting their metabolism to respond to environmental stress, a process known as metabolic transformation. The best-known aspect of metabolic transformation is the Warburg effect, whereby cancer cells up-regulate glycolysis under aerobic conditions. However, other mechanisms mediating metabolic transformation remain undefined. Here we report that carnitine palmitoyltransferase 1C (CPT1C), a brain-specific metabolic enzyme, may participate in metabolic transformation. CPT1C expression correlates inversely with mammalian target of rapamycin (mTOR) pathway activation, contributes to rapamycin resistance in murine primary tumors, and is frequently up-regulated in human lung tumors. Tumor cells constitutively expressing CPT1C show increased fatty acid (FA) oxidation, ATP production, and resistance to glucose deprivation or hypoxia. Conversely, cancer cells lacking CPT1C produce less ATP and are more sensitive to metabolic stress. CPT1C depletion via siRNA suppresses xenograft tumor growth and metformin responsiveness in vivo. CPT1C can be induced by hypoxia or glucose deprivation and is regulated by AMPKα. Cpt1c-deficient murine embryonic stem (ES) cells show sensitivity to hypoxia and glucose deprivation and altered FA homeostasis. Our results indicate that cells can use a novel mechanism involving CPT1C and FA metabolism to protect against metabolic stress. CPT1C may thus be a new therapeutic target for the treatment of hypoxic tumors. PMID:21576264

  12. Carnitine palmitoyltransferase 1C promotes cell survival and tumor growth under conditions of metabolic stress

    PubMed Central

    Zaugg, Kathrin; Yao, Yi; Reilly, Patrick T.; Kannan, Karuppiah; Kiarash, Reza; Mason, Jacqueline; Huang, Ping; Sawyer, Suzanne K.; Fuerth, Benjamin; Faubert, Brandon; Kalliomäki, Tuula; Elia, Andrew; Luo, Xunyi; Nadeem, Vincent; Bungard, David; Yalavarthi, Sireesha; Growney, Joseph D.; Wakeham, Andrew; Moolani, Yasmin; Silvester, Jennifer; Ten, Annick You; Bakker, Walbert; Tsuchihara, Katsuya; Berger, Shelley L.; Hill, Richard P.; Jones, Russell G.; Tsao, Ming; Robinson, Murray O.; Thompson, Craig B.; Pan, Guohua; Mak, Tak W.

    2011-01-01

    Tumor cells gain a survival/growth advantage by adapting their metabolism to respond to environmental stress, a process known as metabolic transformation. The best-known aspect of metabolic transformation is the Warburg effect, whereby cancer cells up-regulate glycolysis under aerobic conditions. However, other mechanisms mediating metabolic transformation remain undefined. Here we report that carnitine palmitoyltransferase 1C (CPT1C), a brain-specific metabolic enzyme, may participate in metabolic transformation. CPT1C expression correlates inversely with mammalian target of rapamycin (mTOR) pathway activation, contributes to rapamycin resistance in murine primary tumors, and is frequently up-regulated in human lung tumors. Tumor cells constitutively expressing CPT1C show increased fatty acid (FA) oxidation, ATP production, and resistance to glucose deprivation or hypoxia. Conversely, cancer cells lacking CPT1C produce less ATP and are more sensitive to metabolic stress. CPT1C depletion via siRNA suppresses xenograft tumor growth and metformin responsiveness in vivo. CPT1C can be induced by hypoxia or glucose deprivation and is regulated by AMPKα. Cpt1c-deficient murine embryonic stem (ES) cells show sensitivity to hypoxia and glucose deprivation and altered FA homeostasis. Our results indicate that cells can use a novel mechanism involving CPT1C and FA metabolism to protect against metabolic stress. CPT1C may thus be a new therapeutic target for the treatment of hypoxic tumors. PMID:21576264

  13. Influence of packaging conditions on natural microbial population growth of endive.

    PubMed

    Charles, Florence; Rugani, Nathalie; Gontard, Nathalie

    2005-05-01

    The influence of three packaging conditions, i.e., unmodified atmosphere packaging (UAP), passive modified atmosphere packaging (MAP), and active MAP, on the natural microbial population growth of endive was investigated at 20 degrees C. For UAP, endive was placed in macroperforated oriented polypropylene pouches that maintained gas composition close to that of air (21 kPa O2 and 0 kPa CO2) but also limited superficial product dehydration. For MAP, endive was placed in low-density polyethylene pouches that induced a 3 kPa O2 and 5 kPa CO2 equilibrium atmosphere composition. Steady state was reached after 25 h of storage with an oxygen absorbing packet (active MAP) compared with 100 h without the packet (passive MAP) and was maintained for 200 h. After 312 h of storage, both active and passive MAP reduced total aerobic mesophile, yeast, and mold population growth compared with endive in UAP. Active MAP accelerated and improved the inhibition of Pseudomonas spp. and Enterobacteriaceae, respectively, probably because of the rapid O2 depletion during the transition period. A shift in the Enterobacteriaceae subpopulation from Rhanella aquatilis to Enterobacter agglomerans was observed for both passive and active MAP. PMID:15895736

  14. Selective simplification and reinforcement of microbial community in autothermal thermophilic aerobic digestion to enhancing stabilization process of sewage sludge by conditioning with ferric nitrate.

    PubMed

    Jin, Ningben; Shou, Zongqi; Yuan, Haiping; Lou, Ziyang; Zhu, Nanwen

    2016-03-01

    The effect of ferric nitrate on microbial community and enhancement of stabilization process for sewage sludge was investigated in autothermal thermophilic aerobic digestion. The disinhibition of volatile fatty acids (VFA) was obtained with alteration of individual VFA concentration order. Bacterial taxonomic identification by 454 high-throughput pyrosequencing found the dominant phylum Proteobacteria in non-dosing group was converted to phylum Firmicutes in dosing group after ferric nitrate added and simplification of bacteria phylotypes was achieved. The preponderant Tepidiphilus sp. vanished, and Symbiobacterium sp. and Tepidimicrobium sp. were the most advantageous phylotypes with conditioning of ferric nitrate. Consequently, biodegradable substances in dissolved organic matters increased, which contributed to the favorable environment for microbial metabolism and resulted in acceleration of sludge stabilization. Ultimately, higher stabilization level was achieved as ratio of soluble chemical oxygen demand to total chemical oxygen demand (TCOD) decreased while TCOD reduced as well in dosing group comparing to non-dosing group. PMID:26773954

  15. Aerobic Anoxygenic Phototrophic Bacteria

    PubMed Central

    Yurkov, Vladimir V.; Beatty, J. Thomas

    1998-01-01

    The aerobic anoxygenic phototrophic bacteria are a relatively recently discovered bacterial group. Although taxonomically and phylogenetically heterogeneous, these bacteria share the following distinguishing features: the presence of bacteriochlorophyll a incorporated into reaction center and light-harvesting complexes, low levels of the photosynthetic unit in cells, an abundance of carotenoids, a strong inhibition by light of bacteriochlorophyll synthesis, and the inability to grow photosynthetically under anaerobic conditions. Aerobic anoxygenic phototrophic bacteria are classified in two marine (Erythrobacter and Roseobacter) and six freshwater (Acidiphilium, Erythromicrobium, Erythromonas, Porphyrobacter, Roseococcus, and Sandaracinobacter) genera, which phylogenetically belong to the α-1, α-3, and α-4 subclasses of the class Proteobacteria. Despite this phylogenetic information, the evolution and ancestry of their photosynthetic properties are unclear. We discuss several current proposals for the evolutionary origin of aerobic phototrophic bacteria. The closest phylogenetic relatives of aerobic phototrophic bacteria include facultatively anaerobic purple nonsulfur phototrophic bacteria. Since these two bacterial groups share many properties, yet have significant differences, we compare and contrast their physiology, with an emphasis on morphology and photosynthetic and other metabolic processes. PMID:9729607

  16. Degenerate nonlinear programming with a quadratic growth condition.

    SciTech Connect

    Anitescu, M.; Mathematics and Computer Science

    2000-01-01

    We show that the quadratic growth condition and the Mangasarian-Fromovitz constraint qualification (MFCQ) imply that local minima of nonlinear programs are isolated stationary points. As a result, when started sufficiently close to such points, an L1 exact penalty sequential quadratic programming algorithm will induce at least R-linear convergence of the iterates to such a local minimum. We construct an example of a degenerate nonlinear program with a unique local minimum satisfying the quadratic growth and the MFCQ but for which no positive semidefinite augmented Lagrangian exists. We present numerical results obtained using several nonlinear programming packages on this example and discuss its implications for some algorithms.

  17. Degradation of TCE using sequential anaerobic biofilm and aerobic immobilized bed reactor

    NASA Technical Reports Server (NTRS)

    Chapatwala, Kirit D.; Babu, G. R. V.; Baresi, Larry; Trunzo, Richard M.

    1995-01-01

    Bacteria capable of degrading trichloroethylene (TCE) were isolated from contaminated wastewaters and soil sites. The aerobic cultures were identified as Pseudomonas aeruginosa (four species) and Pseudomonas fluorescens. The optimal conditions for the growth of aerobic cultures were determined. The minimal inhibitory concentration values of TCE for Pseudomonas sps. were also determined. The aerobic cells were immobilized in calcium alginate in the form of beads. Degradation of TCE by the anaerobic and dichloroethylene (DCE) by aerobic cultures was studied using dual reactors - anaerobic biofilm and aerobic immobilized bed reactor. The minimal mineral salt (MMS) medium saturated with TCE was pumped at the rate of 1 ml per hour into the anaerobic reactor. The MMS medium saturated with DCE and supplemented with xylenes and toluene (3 ppm each) was pumped at the rate of 1 ml per hour into the fluidized air-uplift-type reactor containing the immobilized aerobic cells. The concentrations of TCE and DCE and the metabolites formed during their degradation by the anaerobic and aerobic cultures were monitored by GC. The preliminary study suggests that the anaerobic and aerobic cultures of our isolates can degrade TCE and DCE.

  18. INACTIVATION OF ENTERIC PATHOGENS DURING AEROBIC DIGESTION OF WASTEWATER SLUDGE

    EPA Science Inventory

    The effects of aerobic and anaerobic digestion on enteric viruses, enteric bacteria, total aerobic bacteria, and intestinal parasites were studied under laboratory and field conditions. Under laboratory conditions, the temperature of the sludge digestion was the major factor infl...

  19. [Heterotrophic Nitrification and Aerobic Denitrification of the Hypothermia Aerobic Denitrification Bacterium: Arthrobacter arilaitensis].

    PubMed

    He, Teng-xia; Ni, Jiu-pai; Li, Zhen-lun; Sun, Quan; Ye Qing; Xu, Yi

    2016-03-15

    High concentrations of ammonium, nitrate and nitrite nitrogen were employed to clarify the abilities of heterotrophic nitrification and aerobic denitrification of Arthrobacter arilaitensis strain Y-10. Meanwhile, by means of inoculating the strain suspension into the mixed ammonium and nitrate, ammonium and nitrite nitrogen simulated wastewater, we studied the simultaneous nitrification and denitrification ability of Arthrobacter arilaitensis strain Y-10. In addition, cell optical density was assayed in each nitrogen removal process to analyze the relationship of cell growth and nitrogen removal efficiency. The results showed that the hypothermia denitrification strain Arthrobacter arilaitensis Y-10 exhibited high nitrogen removal efficiency during heterotrophic nitrification and aerobic denitrification. The ammonium, nitrate and nitrite removal rates were 65.0%, 100% and 61.2% respectively when strain Y-10 was cultivated for 4 d at 15°C with initial ammonium, nitrate and nitrite nitrogen concentrations of 208.43 mg · L⁻¹, 201.16 mg · L⁻¹ and 194.33 mg · L⁻¹ and initial pH of 7.2. Nitrite nitrogen could only be accumulated in the medium containing nitrate nitrogen during heterotrophic nitrification and aerobic denitrification process. Additionally, the ammonium nitrogen was mainly removed in the inorganic nitrogen mixed synthetic wastewater. In short, Arthrobacter arilaitensis Y-10 could conduct nitrification and denitrification effectively under aerobic condition and the ammonium nitrogen removal rate was more than 80.0% in the inorganic nitrogen mixed synthetic wastewater. PMID:27337904

  20. Antimicrobial Treatment Improves Mycobacterial Survival in Nonpermissive Growth Conditions

    PubMed Central

    Turapov, Obolbek; Waddell, Simon J.; Burke, Bernard; Glenn, Sarah; Sarybaeva, Asel A.; Tudo, Griselda; Labesse, Gilles; Young, Danielle I.; Young, Michael; Andrew, Peter W.; Butcher, Philip D.; Cohen-Gonsaud, Martin

    2014-01-01

    Antimicrobials targeting cell wall biosynthesis are generally considered inactive against nonreplicating bacteria. Paradoxically, we found that under nonpermissive growth conditions, exposure of Mycobacterium bovis BCG bacilli to such antimicrobials enhanced their survival. We identified a transcriptional regulator, RaaS (for regulator of antimicrobial-assisted survival), encoded by bcg1279 (rv1219c) as being responsible for the observed phenomenon. Induction of this transcriptional regulator resulted in reduced expression of specific ATP-dependent efflux pumps and promoted long-term survival of mycobacteria, while its deletion accelerated bacterial death under nonpermissive growth conditions in vitro and during macrophage or mouse infection. These findings have implications for the design of antimicrobial drug combination therapies for persistent infectious diseases, such as tuberculosis. PMID:24590482

  1. Crystal growth under microgravity conditions with using of magnetic fields

    NASA Astrophysics Data System (ADS)

    Feonychev, A.; Bondareva, N.

    The peculiarities of melt flows and crystal growth by the Bridgman and floating zone methods aboard spacecrafts under the action of steady axial or rotating magnetic field are considered. Steady magnetic field can minimize adverse effect of residual accelerations and vibrations on dopant segregation in crystals growing by the Bridgman method but it requires using strong magnetic fields, which induces specific oscillations. Under strong convection in terrestrial conditions steady magnetic field gives positive effect. Under growth of small-sized crystals by the floating zone method in microgravity conditions an use of steady magnetic field brings into dramatic increase of radial segregation due to convective vortex to free fluid surface. The flows being created by rotating magnetic field and resultant under combination of Marangoni convection with rotating magnetic field were studied for wide range of parameters including the regimes of oscillatory (turbulent) convection. Mathematical model and computer program was tested by published results of two experiments. The dependence of transition from laminar to oscillatory flow was obtained for different boundary conditions, geometric parameters of fluid and intensity of magnetic field. Specific oscillations with very low frequency and oscillations of the beating type had been discovered under the action rotating magnetic field on Marangoni convection. The mutual influence of rotating magnetic field and thermocapillary convection on flow stability was noted. Use of rotating magnetic field under crystal growth by floating zone method leads to reduction of azimuth velocity which is responsible for origin of oscillatory convection and striation of crystals. It was shown on concrete examples that there is a possibility to reduce radial segregation under optimization of rotating velocity and intensity of magnetic field. For the Bridgman method (in general for ampoule methods of crystal growth), the use of rotating magnetic

  2. Isolation of high-salinity-tolerant bacterial strains, Enterobacter sp., Serratia sp., Yersinia sp., for nitrification and aerobic denitrification under cyanogenic conditions.

    PubMed

    Mpongwana, N; Ntwampe, S K O; Mekuto, L; Akinpelu, E A; Dyantyi, S; Mpentshu, Y

    2016-01-01

    Cyanides (CN(-)) and soluble salts could potentially inhibit biological processes in wastewater treatment plants (WWTPs), such as nitrification and denitrification. Cyanide in wastewater can alter metabolic functions of microbial populations in WWTPs, thus significantly inhibiting nitrifier and denitrifier metabolic processes, rendering the water treatment processes ineffective. In this study, bacterial isolates that are tolerant to high salinity conditions, which are capable of nitrification and aerobic denitrification under cyanogenic conditions, were isolated from a poultry slaughterhouse effluent. Three of the bacterial isolates were found to be able to oxidise NH(4)-N in the presence of 65.91 mg/L of free cyanide (CN(-)) under saline conditions, i.e. 4.5% (w/v) NaCl. The isolates I, H and G, were identified as Enterobacter sp., Yersinia sp. and Serratia sp., respectively. Results showed that 81% (I), 71% (G) and 75% (H) of 400 mg/L NH(4)-N was biodegraded (nitrification) within 72 h, with the rates of biodegradation being suitably described by first order reactions, with rate constants being: 4.19 h(-1) (I), 4.21 h(-1) (H) and 3.79 h(-1) (G), respectively, with correlation coefficients ranging between 0.82 and 0.89. Chemical oxygen demand (COD) removal rates were 38% (I), 42% (H) and 48% (G), over a period of 168 h with COD reduction being highest at near neutral pH. PMID:27148718

  3. The effect of salinization and freshening events in coastal aquifers on nutrient characteristics as deduced from column experiments under aerobic and anaerobic conditions

    NASA Astrophysics Data System (ADS)

    Russak, A.; Sivan, O.; Herut, B.; Lazar, B.; Yechieli, Y.

    2015-10-01

    This study experimentally quantified the effect of seawater intrusion (salinization) and freshening events in coastal aquifers on nutrient (N, P and DSi) dynamics across the fresh-saline groundwater interface. Laboratory column experiments were conducted under aerobic and anaerobic conditions in order to simulate the processes occurring in the fresh-saline interface. They were performed with aquifer sediments, simulating the natural conditions during alterations of natural fresh groundwater to seawater and vice versa. The salinization and freshening experiments showed that NH4+ and PO43- and DSi were affected mainly by ion exchange processes while microbial activity controlled the nitrogen species NO3- and NO2-. Due to the cation exchange, salinization generated enrichment (above the expected conservative behavior) of NH4+, up to 80 μmol L-1 (an order of magnitude higher than in seawater or fresh groundwater). Under anaerobic conditions NO3- was removed by denitrification, as demonstrated by the decrease in NO3- concentrations, the increase in NO2- concentrations, and the increase in δ15N by 15-25‰. Clear evidence was shown for anion exchange of PO43-, which competes with HCO3- and boron on adsorption sites. DSi seems to take part in the exchange process, similar to PO43-.

  4. Modeling the Growth of Epiphytic Bacteria on Kale Treated by Thermosonication Combined with Slightly Acidic Electrolyzed Water and Stored under Dynamic Temperature Conditions.

    PubMed

    Mansur, Ahmad Rois; Oh, Deog-Hwan

    2016-08-01

    The growth of epiphytic bacteria (aerobic mesophilic bacteria or Pseudomonas spp.) on kale was modeled isothermally and validated under dynamic storage temperatures. Each bacterial count on kale stored at isothermal conditions (4 to 25 °C) was recorded. The results show that maximum growth rate (μmax ) of both epiphytic bacteria increased and lag time (λ) decreased with increasing temperature (P < 0.05). The maximum population density (Nmax ) of Pseudomonas spp. was significantly greater than that of aerobic mesophilic bacteria, particularly in treated samples and/or at 4 and 10 °C (P < 0.05). The relationship between μmax of both epiphytic bacteria and temperature was linear (R(2) > 0.97), whereas lower R(2) > 0.86 and R(2) > 0.87 was observed for the λ and Nmax , respectively. The overall predictions of both epiphytic bacterial growths under nonisothermal conditions with temperature abuse of 15 °C agreed with the observed data, whereas those with temperature abuse of 25 °C were greatly overestimated. The appropriate parameter q0 (physiological state of cells), therefore, was adjusted by a trial and error to fit the model. This study demonstrates that the developed model was able to predict accurately epiphytic bacterial growth on kale stored under nonisothermal conditions particularly those with low temperature abuse of 15 °C. PMID:27387251

  5. Effect of lighting conditions on zebrafish growth and development.

    PubMed

    Villamizar, Natalia; Vera, Luisa María; Foulkes, Nicholas Simon; Sánchez-Vázquez, Francisco Javier

    2014-04-01

    In the underwater environment, the properties of light (intensity and spectrum) change rapidly with depth and water quality. In this article, we have described how and to what extent lighting conditions can influence the development, growth, and survival of zebrafish. Fertilized eggs and the corresponding larvae were exposed to different visible light wavelengths (violet, blue, green, yellow, red, and white) in a 12-h light-12-h dark (LD) cycle until 30 days posthatching (dph), when the expression of morphometric parameters and growth (igf1a, igf2a)- and stress-related (crh and pomca) genes were examined. Another group of larvae was raised under constant darkness (DD) until 5 or 10 dph, after which they were transferred to a LD of white light. A third group remained under DD to investigate the effects of light deprivation upon zebrafish development. The results revealed that the hatching rate was highest under blue and violet light, while total length at 30 dph was greatest under blue, white, and violet light. Red light led to reduced feeding activity and poor survival (100% mortality). Larvae raised under constant white light (LL) showed a higher proportion of malformations, as did larvae raised under LD violet light. The expression of growth and stress factors was upregulated in the violet (igf1a, igf2a, pomca, and chr) and blue (igf2a) groups, which is consistent with the higher growth recorded and the higher proportion of malformations detected under the violet light. All larvae kept under DD died before 18 dph, but the survival rates improved in larvae transferred to LD at 5 dph and at 10 dph. In summary, these findings revealed that lighting conditions are crucial factors influencing zebrafish larval development and growth. PMID:24367902

  6. Media and growth conditions for induction of secondary metabolite production.

    PubMed

    Frisvad, Jens C

    2012-01-01

    Growth media and incubation conditions have a very strong influence of secondary metabolite production. There is no consensus on which media are the optimal for metabolite production, but a series of useful and effective media and incubation conditions have been listed here. Chemically well-defined media are suited for biochemical studies, but in order to get chemical diversity expressed in filamentous fungi, sources rich in amino acids, vitamins, and trace metals have to be added, such as yeast extract and oatmeal. A battery of solid agar media is recommended for exploration of chemical diversity as agar plug samples are easily analyzed to get an optimal representation of the qualitative secondary metabolome. Standard incubation for a week at 25°C in darkness is recommended, but optimal conditions have to be modified depending on the ecology and physiology of different filamentous fungi. PMID:23065607

  7. MALDI-TOF MS Imaging evidences spatial differences in the degradation of solid polycaprolactone diol in water under aerobic and denitrifying conditions.

    PubMed

    Rivas, Daniel; Ginebreda, Antoni; Pérez, Sandra; Quero, Carmen; Barceló, Damià

    2016-10-01

    Degradation of solid polymers in the aquatic environment encompasses a variety of biotic and abiotic processes giving rise to heterogeneous patterns across the surface of the material, which cannot be investigated using conventional Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) that only renders an "average" picture of the sample. In that context, MALDI-TOF MS Imaging (MALDI MSI) provides a rapid and efficient tool to study 2D spatial changes occurred in the chemical composition of the polymer surface. Commercial polycaprolactone diol (average molecular weight of 1250Da) was selected as test material because it had been previously known to be amenable to biological degradation. The test oligomer probe was incubated under aerobic and denitrifying conditions using synthetic water and denitrifying mixed liquor obtained from a wastewater treatment plant respectively. After ca. seven days of exposure the mass spectra obtained by MALDI MSI showed the occurrence of chemical modifications in the sample surface. Observed heterogeneity across the probe's surface indicated significant degradation and suggested the contribution of biotic processes. The results were investigated using different image processing tools. Major changes on the oligomer surface were observed when exposed to denitrifying conditions. PMID:27213667

  8. Optimal conditions of mycelia growth of Laetiporus sulphureus sensu lato

    PubMed Central

    Luangharn, Thatsanee; Karunarathna, Samantha C.; Hyde, Kevin D.; Chukeatirote, Ekachai

    2014-01-01

    Laetiporus sulphureus is an edible wood-rotting basidiomycete, growing on decaying logs, stumps, and trunks of many deciduous and coniferous tree species. This fungus produces relatively large striking yellowish or orange-coloured bracket-like fruitbodies. L. sulphureus is widely consumed as a nutritional food because of its fragrance and texture. In this study, two L. sulphureus strains, MFLUCC 12-0546 and MFLUCC 12-0547, isolated from Chiang Rai, Thailand, were investigated for optimal conditions of mycelia growth. Potato dextrose agar and malt extract agar were observed as the favourable medium for mycelia growth. The optimum pH and temperature for the mushroom mycelia were 6–8 and 25–30°C, respectively. PMID:25544934

  9. Microbial aerobic and anaerobic degradation of acrylamide in sludge and water under environmental conditions--case study in a sand and gravel quarry.

    PubMed

    Guezennec, A G; Michel, C; Ozturk, S; Togola, A; Guzzo, J; Desroche, N

    2015-05-01

    Polyacrylamides (PAMs) are used in sand and gravel quarries as water purification flocculants for recycling process water in a recycling loop system where the flocculants remove fine particles in the form of sludge. The PAM-based flocculants, however, contain residual amounts of acrylamide (AMD) that did not react during the polymerization process. This acrylamide is released into the environment when the sludge is discharged into a settling basin. Here, we explore the microbial diversity and the potential for AMD biodegradation in water and sludge samples collected in a quarry site submitted to low AMD concentrations. The microbial diversity, analyzed by culture-dependent methods and the denaturing gradient gel electrophoresis approach, reveals the presence of Proteobacteria, Cyanobacteria, and Actinobacteria, among which some species are known to have an AMD biodegradation activity. Results also show that the two main parts of the water recycling loop-the washing process and the settling basin-display significantly different bacterial profiles. The exposure time with residual AMD could, thus, be one of the parameters that lead to a selection of specific bacterial species. AMD degradation experiments with 0.5 g L(-1) AMD showed a high potential for biodegradation in all parts of the washing process, except the make-up water. The AMD biodegradation potential in samples collected from the washing process and settling basin was also analyzed taking into account on-site conditions: low (12 °C) and high (25 °C) temperatures reflecting the winter and summer seasons, and AMD concentrations of 50 μg L(-1). Batch tests showed rapid (as little as 18 h) AMD biodegradation under aerobic and anaerobic conditions at both the winter and summer temperatures, although there was a greater lag time before activity started with the AMD biodegradation at 12 °C. This study, thus, demonstrates that bacteria present in sludge and water samples exert an in situ and rapid

  10. Characteristics of a Novel Aerobic Denitrifying Bacterium, Enterobacter cloacae Strain HNR.

    PubMed

    Guo, Long-Jie; Zhao, Bin; An, Qiang; Tian, Meng

    2016-03-01

    A novel aerobic denitrifier strain HNR, isolated from activated sludge, was identified as Enterobacter cloacae by16S rRNA sequencing analysis. Glucose was considered as the most favorable C-source for strain HNR. The logistic equation well described the bacterial growth, yielding a maximum growth rate (μmax) of 0.283 h(-1) with an initial NO3 (-)-N concentration of 110 mg/L. Almost all NO3 (-)-N was removed aerobically within 30 h with an average removal rate of 4.58 mg N L(-1) h(-1). Nitrogen balance analysis revealed that proximately 70.8 % of NO3 (-)-N was removed as gas products and only 20.7 % was transformed into biomass. GC-MS result indicates that N2 was the end product of aerobic denitrification. The enzyme activities of nitrate reductase and nitrite reductase, which are related to the process of aerobic denitrification, were 0.0688 and 0.0054 U/mg protein, respectively. Thus, the aerobic denitrification of reducing NO3 (-) to N2 by strain HNR was demonstrated. The optimal conditions for nitrate removal were C/N ratio 13, pH value 8, shaking speed 127 rpm and temperature 30 °C. These findings show that E. cloacae strain HNR has a potential application on wastewater treatment to achieve nitrate removal under aerobic conditions. PMID:26573667

  11. Adherence to abiotic surface induces SOS response in Escherichia coli K-12 strains under aerobic and anaerobic conditions.

    PubMed

    Costa, Suelen B; Campos, Ana Carolina C; Pereira, Ana Claudia M; de Mattos-Guaraldi, Ana Luiza; Júnior, Raphael Hirata; Rosa, Ana Cláudia P; Asad, Lídia M B O

    2014-09-01

    During the colonization of surfaces, Escherichia coli bacteria often encounter DNA-damaging agents and these agents can induce several defence mechanisms. Base excision repair (BER) is dedicated to the repair of oxidative DNA damage caused by reactive oxygen species (ROS) generated by chemical and physical agents or by metabolism. In this work, we have evaluated whether the interaction with an abiotic surface by mutants derived from E. coli K-12 deficient in some enzymes that are part of BER causes DNA damage and associated filamentation. Moreover, we studied the role of endonuclease V (nfi gene; 1506 mutant strain) in biofilm formation. Endonuclease V is an enzyme that is involved in DNA repair of nitrosative lesions. We verified that endonuclease V is involved in biofilm formation. Our results showed more filamentation in the xthA mutant (BW9091) and triple xthA nfo nth mutant (BW535) than in the wild-type strain (AB1157). By contrast, the mutant nfi did not present filamentation in biofilm, although its wild-type strain (1466) showed rare filaments in biofilm. The filamentation of bacterial cells attaching to a surface was a consequence of SOS induction measured by the SOS chromotest. However, biofilm formation depended on the ability of the bacteria to induce the SOS response since the mutant lexA Ind(-) did not induce the SOS response and did not form any biofilm. Oxygen tension was an important factor for the interaction of the BER mutants, since these mutants exhibited decreased quantitative adherence under anaerobic conditions. However, our results showed that the presence or absence of oxygen did not affect the viability of BW9091 and BW535 strains. The nfi mutant and its wild-type did not exhibit decreased biofilm formation under anaerobic conditions. Scanning electron microscopy was also performed on the E. coli K-12 strains that had adhered to the glass, and we observed the presence of a structure similar to an extracellular matrix that depended on the

  12. Effect of Several Environmental Conditions on the “Thermal Death Rate” of Endospores of Aerobic, Thermophilic Bacteria

    PubMed Central

    Yokoya, Fumio; York, George K.

    1965-01-01

    The composition of the recovery medium affected the apparent heat resistance of Bacillus stearothermophilus when the pH of the medium was 7.0 but not when the pH was 6.5. The rate of thermal death at 110 C was exponential. Deviations from exponential rates of thermal death during the initial phases of heating at 96 C were observed with endospores of B. coagulans under different conditions of sporulation. Additionally, the apparent heat resistance was influenced by the composition of the media used for sporulation and recovery and by the composition of the suspending menstruum. The presence of 0.001 m sorbic acid in the suspending menstruum at pH 7.0 and the temperature of incubation of the cultures after heating did not affect the apparent heat resistance of B. coagulans. Several explanations are discussed for the observed deviations from exponential thermal death rates and the effect of the environment on the apparent heat resistance of B. coagulans. PMID:5866047

  13. Hydrogen photoproduction by nutrient-deprived Chlamydomonas reinhardtii cells immobilized within thin alginate films under aerobic and anaerobic conditions.

    PubMed

    Kosourov, Sergey N; Seibert, Michael

    2009-01-01

    A new technique for immobilizing H2-photoproducing green algae within a thin (<400 microm) alginate film has been developed. Alginate films with entrapped sulfur/phosphorus-deprived Chlamydomonas reinhardtii, strain cc124, cells demonstrate (a) higher cell density (up to 2,000 microg Chl mL(-1) of matrix), (b) kinetics of H2 photoproduction similar to sulfur-deprived suspension cultures, (c) higher specific rates (up to 12.5 micromol mg(-1) Chl h(-1)) of H2 evolution, (d) light conversion efficiencies to H2 of over 1% and (e) unexpectedly high resistance of the H2-photoproducing system to inactivation by atmospheric O2. The algal cells, entrapped in alginate and then placed in vials containing 21% O2 in the headspace, evolved up to 67% of the H2 gas produced under anaerobic conditions. The results indicate that the lower susceptibility of the immobilized algal H2-producing system to inactivation by O2 depends on two factors: (a) the presence of acetate in the medium, which supports higher rates of respiration and (b) the capability of the alginate polymer itself to effectively separate the entrapped cells from O2 in the liquid and headspace and restrict O2 diffusion into the matrix. The strategy presented for immobilizing algal cells within thin polymeric matrices shows the potential for scale-up and possible future applications. PMID:18823051

  14. Hydrogen Photoproduction by Nutrient-Deprived Chalamydomonas reinhardtii Cells Immobilized Within Thin Alginate Films Under Aerobic and Anaerobic Conditions

    SciTech Connect

    Kosourov, S. N.; Seibert, M.

    2009-01-01

    A new technique for immobilizing H{sub 2}-photoproducing green algae within a thin (<400 {micro}m) alginate film has been developed. Alginate films with entrapped sulfur/phosphorus-deprived Chlamydomonas reinhardtii, strain cc124, cells demonstrate (a) higher cell density (up to 2,000 {micro}g Chl mL{sup -1} of matrix), (b) kinetics of H{sub 2} photoproduction similar to sulfur-deprived suspension cultures, (c) higher specific rates (up to 12.5 {micro}mol mg{sup -1} Chl h{sup -1}) of H{sub 2} evolution, (d) light conversion efficiencies to H{sub 2} of over 1% and (e) unexpectedly high resistance of the H{sub 2}-photoproducing system to inactivation by atmospheric O{sub 2}. The algal cells, entrapped in alginate and then placed in vials containing 21% O{sub 2} in the headspace, evolved up to 67% of the H{sub 2} gas produced under anaerobic conditions. The results indicate that the lower susceptibility of the immobilized algal H{sub 2}-producing system to inactivation by O{sub 2} depends on two factors: (a) the presence of acetate in the medium, which supports higher rates of respiration and (b) the capability of the alginate polymer itself to effectively separate the entrapped cells from O{sub 2} in the liquid and headspace and restrict O{sub 2} diffusion into the matrix. The strategy presented for immobilizing algal cells within thin polymeric matrices shows the potential for scale-up and possible future applications.

  15. Optimization of operation conditions for the mitigation of nitrous oxide (N2O) emissions from aerobic nitrifying granular sludge system.

    PubMed

    Liu, Rui-Ting; Wang, Xin-Hua; Zhang, Yan; Wang, Ming-Yu; Gao, Ming-Ming; Wang, Shu-Guang

    2016-05-01

    The optimization of operation parameters is a key consideration to minimize nitrous oxide (N2O) emissions in biological nitrogen removal processes. So far, different parameters have only been investigated individually, making it difficult to compare their specific effects and combined influences. In this study, we applied the Plackett-Burman (PB) multifactorial experimental design and response surface methodology (RSM) analysis to find the optimized condition for the mitigation of N2O release in a nitrifying granular sludge system. Seven parameters (temperature, pH, feeding strategy, C/N ratio, aeration rate, Cu(2+) concentration, and aeration mode) were tested in parallel. Five of them (other than chemical oxygen demand/nitrogen (C/N) ratio and Cu(2+) concentration) were selected as influential factors. Since the type of feeding strategies and aeration modes cannot be quantified, continuous feed strategy and anoxic/oxic aeration mode were applied for the following study. Influences of temperature, pH, and aeration rate on N2O emissions were tested with RSM analysis to further investigate the mutual interactions among the parameters and to identify the optimal values that would minimize N2O release. Results showed the minimum emission value could be obtained under the temperature of 22.3 °C, pH of 7.1 and aeration rate of 0.20 m(3)/h. Predicted results were then verified by subsequent validation experiments. The estimated N2O emission value of each design by RSM was also observed in good relationships with experimental result. PMID:26841778

  16. A Putative ABC Transporter Permease Is Necessary for Resistance to Acidified Nitrite and EDTA in Pseudomonas aeruginosa under Aerobic and Anaerobic Planktonic and Biofilm Conditions

    PubMed Central

    McDaniel, Cameron; Su, Shengchang; Panmanee, Warunya; Lau, Gee W.; Browne, Tristan; Cox, Kevin; Paul, Andrew T.; Ko, Seung-Hyun B.; Mortensen, Joel E.; Lam, Joseph S.; Muruve, Daniel A.; Hassett, Daniel J.

    2016-01-01

    Pseudomonas aeruginosa (PA) is an important airway pathogen of cystic fibrosis and chronic obstructive disease patients. Multiply drug resistant PA is becoming increasing prevalent and new strategies are needed to combat such insidious organisms. We have previously shown that a mucoid, mucA22 mutant PA is exquisitely sensitive to acidified nitrite (A-NO2−, pH 6.5) at concentrations that are well tolerated in humans. Here, we used a transposon mutagenesis approach to identify PA mutants that are hypersensitive to A-NO2−. Among greater than 10,000 mutants screened, we focused on PA4455, in which the transposon was found to disrupt the production of a putative cytoplasmic membrane-spanning ABC transporter permease. The PA4455 mutant was not only highly sensitive to A-NO2−, but also the membrane perturbing agent, EDTA and the antibiotics doxycycline, tigecycline, colistin, and chloramphenicol, respectively. Treatment of bacteria with A-NO2− plus EDTA, however, had the most dramatic and synergistic effect, with virtually all bacteria killed by 10 mM A-NO2−, and EDTA (1 mM, aerobic, anaerobic). Most importantly, the PA4455 mutant was also sensitive to A-NO2− in biofilms. A-NO2− sensitivity and an anaerobic growth defect was also noted in two mutants (rmlC and wbpM) that are defective in B-band LPS synthesis, potentially indicating a membrane defect in the PA4455 mutant. Finally, this study describes a gene, PA4455, that when mutated, allows for dramatic sensitivity to the potential therapeutic agent, A-NO2− as well as EDTA. Furthermore, the synergy between the two compounds could offer future benefits against antibiotic resistant PA strains. PMID:27064218

  17. Induction of Salmonella pathogenicity island 1 under different growth conditions can affect Salmonella–host cell interactions in vitro

    PubMed Central

    Ibarra, J. Antonio; Knodler, Leigh A.; Sturdevant, Daniel E.; Virtaneva, Kimmo; Carmody, Aaron B.; Fischer, Elizabeth R.; Porcella, Stephen F.; Steele-Mortimer, Olivia

    2010-01-01

    Salmonella invade non-phagocytic cells by inducing massive actin rearrangements, resulting in membrane ruffle formation and phagocytosis of the bacteria. This process is mediated by a cohort of effector proteins translocated into the host cell by type III secretion system 1, which is encoded by genes in the Salmonella pathogenicity island (SPI) 1 regulon. This network is precisely regulated and must be induced outside of host cells. In vitro invasive Salmonella are prepared by growth in synthetic media although the details vary. Here, we show that culture conditions affect the frequency, and therefore invasion efficiency, of SPI1-induced bacteria and also can affect the ability of Salmonella to adapt to its intracellular niche following invasion. Aerobically grown late-exponential-phase bacteria were more invasive and this was associated with a greater frequency of SPI1-induced, motile bacteria, as revealed by single-cell analysis of gene expression. Culture conditions also affected the ability of Salmonella to adapt to the intracellular environment, since they caused marked differences in intracellular replication. These findings show that induction of SPI1 under different pre-invasion growth conditions can affect the ability of Salmonella to interact with eukaryotic host cells. PMID:20035008

  18. Growth management of vetiver (Vetiveria zizanioides) under Mediterranean conditions.

    PubMed

    Dudai, N; Putievsky, E; Chaimovitch, D; Ben-Hur, M

    2006-10-01

    In spite of the advantages of Vetiver grass in light of environmental aspects, this plant is not used in the Mediterranean region. The objectives of the present study were: (i) to elucidate growth parameters and establishment of Vetiver under Mediterranean conditions suitable for its various environmental applications; and (ii) to develop management practices for growing vetiver under Mediterranean conditions. In greenhouse experiments conducted under controlled conditions it was found that, in general, increasing the minimum/maximum temperatures to 21-29 degrees C significantly increased plant height. In the Mediterranean region, this range of air temperatures is obtained mainly during the summer, from June to September. For air temperatures up to 15-23 degrees C the effect of day length on plant height was insignificant, whereas in air temperature >15-23 degrees C, the plant heights under long day conditions were significantly higher than under short day. The number of sprouts per plant increased exponentially with increasing air temperature, and was not significantly affected by the day length at any air temperature range. In open fields, the heights of irrigated vetiver plants were significantly higher than those of rain-fed plants. It was concluded that, once they were established, vetiver plants could survive the dry summer of the Mediterranean region under rain-fed conditions, but they would be shorter than under irrigation. Cutting or burning of the plant foliage during the spring did not improve the survival of vetiver during the dry summer. In order to obtain fast growth of vetiver and to increase the possibility of its using the rainwater, the plants should be planted in the winter, during February and March. However, under this regime, the vetiver plant cannot be used as a soil stabilizer during the first winter, because the plant is still small. In contrast, under irrigation it is advantageous to plant vetiver at the beginning of the summer; the plant

  19. Aerobic Fitness for the Moderately Retarded.

    ERIC Educational Resources Information Center

    Bauer, Dan

    1981-01-01

    Intended for physical education teachers, the booklet offers ideas for incorporating aerobic conditioning into programs for moderately mentally retarded students. An explanation of aerobic fitness and its benefits is followed by information on initiating a fitness program with evaluation of height, weight, body fat, resting heart rate, and…

  20. Aerobic Dancing--A Rhythmic Sport.

    ERIC Educational Resources Information Center

    Sorensen, Jacki

    Fitness programs now and in the future must offer built-in cardiovascular conditioning, variety, novelty, and change to meet the physical, mental, and emotional needs of our society. Aerobic dancing (dancing designed to train and strengthen the heart, lungs, and vascular system) is one of the first indoor group Aerobic exercise programs designed…

  1. Growth of immature Chironomus calligraphus in laboratory conditions.

    PubMed

    Canteiro, Rita de Cássia S A; Albertoni, Edélti F

    2011-12-01

    Chironomidae larvae are important macroinvertebrates in limnic environments, but little knowledge exists about their biometrics development characteristics. This study aims to describe the immature Chironomus calligraphus Goeldi, 1905 under laboratory conditions by the accomplishment of thirteen egg masses from eggs eclosion to adults emergency, at controlled room temperature (25ºC) and photoperiod (12-12h). Larvae were feed ad libitum with "Alcon Basic - MEP 200 Complex" fish food and commercial dehydrated Spirulina. The postures had a mean length of 9 ± 1 mm (n = 13) and 348 ± 66 eggs. The brownish colored eggs with elliptical shape had length of 160.3 ± 17.7 µm (n = 130), being arranged as an organized string in a pseudo spiral form. The time duration from the first to the four instars were three, four, four and eight days, and the average length of a cephalic capsule to each one of the instars (66.3 ± 12.3 µm, 102.9 ± 22.1 µm, 159 ± 24.6 µm, 249.2 ± 29.7 µm, n = 456) were significantly different (ANOVA, p < 0.001). The Dyar’s Rule showed a constant growth rate, r = 1.5. Our results demonstrated that C. calligraphus is a species with short life cycle, low mortality rate, food adaptability, fast larval growth and easily maintained at laboratory, factors that allowed the use of this native species as a tool for ecotoxicological tests. PMID:21971596

  2. Fibroblast Growth Factors and Vascular Endothelial Growth Factor Promote Cardiac Reprogramming under Defined Conditions

    PubMed Central

    Yamakawa, Hiroyuki; Muraoka, Naoto; Miyamoto, Kazutaka; Sadahiro, Taketaro; Isomi, Mari; Haginiwa, Sho; Kojima, Hidenori; Umei, Tomohiko; Akiyama, Mizuha; Kuishi, Yuki; Kurokawa, Junko; Furukawa, Tetsushi; Fukuda, Keiichi; Ieda, Masaki

    2015-01-01

    Summary Fibroblasts can be directly reprogrammed into cardiomyocyte-like cells (iCMs) by overexpression of cardiac transcription factors, including Gata4, Mef2c, and Tbx5; however, this process is inefficient under serum-based culture conditions, in which conversion of partially reprogrammed cells into fully reprogrammed functional iCMs has been a major hurdle. Here, we report that a combination of fibroblast growth factor (FGF) 2, FGF10, and vascular endothelial growth factor (VEGF), termed FFV, promoted cardiac reprogramming under defined serum-free conditions, increasing spontaneously beating iCMs by 100-fold compared with those under conventional serum-based conditions. Mechanistically, FFV activated multiple cardiac transcriptional regulators and converted partially reprogrammed cells into functional iCMs through the p38 mitogen-activated protein kinase and phosphoinositol 3-kinase/AKT pathways. Moreover, FFV enabled cardiac reprogramming with only Mef2c and Tbx5 through the induction of cardiac reprogramming factors, including Gata4. Thus, defined culture conditions promoted the quality of cardiac reprogramming, and this finding provides new insight into the mechanism of cardiac reprogramming. PMID:26626177

  3. Growth patterns for etiolated soybeans germinated under spaceflight conditions

    NASA Astrophysics Data System (ADS)

    Levine, Howard G.; Piastuch, William C.

    In the GENEX (GENe EXpression) spaceflight experiment (flown on STS-87), six surface sterilized soybean seeds ( Glycine max cv McCall) were inserted into each of 32 autoclaved plastic seed growth pouches containing an inner germination paper sleeve (for a total of 192 seeds). The pouches were stowed within a mid-deck locker until Mission Flight Day 10, at which time an astronaut added water to initiate the process of seed germination on-orbit and subsequently transferred them to four light-tight aluminum canisters called BRIC-60s (Biological Research In Canisters). We report here on the morphological characteristics of: (1) the recovered flight plants ( N = 177), (2) the corresponding ground control population ( N = 183), plus (3) additional controls grown on the ground under clinostat conditions ( N = 93). No significant morphological differences were found between the flight, ground control and clinorotated treatments for either the cotyledons or hypocotyls. There were, however, significantly longer primary roots produced in the flight population relative to the ground control population, which in turn had significantly longer primary roots than the clinorotated population. This same pattern was observed relative to the production of lateral roots (flight > control > clinorotated). Taken together with previous literature reports, we believe that there is now sufficient evidence to conclude that plants grown under conditions of microgravity will generally exhibit enhanced root production relative to their ground control counterparts. Some causes underlying this phenomenon are speculated on.

  4. Volatile chemical spoilage indexes of raw Atlantic salmon (Salmo salar) stored under aerobic condition in relation to microbiological and sensory shelf lives.

    PubMed

    Mikš-Krajnik, Marta; Yoon, Yong-Jin; Ukuku, Dike O; Yuk, Hyun-Gyun

    2016-02-01

    The purpose of this investigation was to identify and quantify the volatile chemical spoilage indexes (CSIs) for raw Atlantic salmon (Salmo salar) fillets stored under aerobic storage conditions at 4, 10 and 21 °C in relation to microbial and sensory shelf lives. The volatile organic compounds (VOCs) were analyzed with SPME-GC-MS technique. Through multivariate chemometric method, hierarchical cluster analysis (HCA) and Pearson's correlations, the CSIs: trimethylamine (TMA), ethanol (EtOH), 3-methyl-1-butanol (3Met-1But), acetoin and acetic acid (C2) were selected from the group of 28 detected VOCs. At the moment of microbiological shelf life established at total viable count (TVC) of 7.0 log CFU/g, the CSIs achieved levels of 11.5, 38.3, 0.3, 24.0 and 90.7 μg/g of salmon for TMA, EtOH, 3M-1But, acetoin and C2, respectively. Pseudomonas spp. was found as major specific spoilage organism (SSOs), suitable for shelf life prediction using modified Gompertz model at the cut-off level of 6.5 log CFU/g. H2S producing bacteria and Brochothrix thermosphacta were considered as important spoilage microorganisms; however, they were not suitable for shelf life estimation. Partial least square (PLS) regression revealed possible associations between microorganisms and synthetized VOCs, showing correlations between Pseudomonas spp. and 3Met-1But and aldehydes synthesis, lactic acid bacteria were linked with EtOH, C2 and esters, and B. thermosphacta with acetoin formation. PMID:26678146

  5. The effect of aerobic conditions on the complexation ability between mercury and humic acid from landfill leachate and its implication for the environment.

    PubMed

    Chai, Xiaoli; Hao, Yongxia; Liu, Guixiang; Li, Zhonggen; Zhao, Youcai

    2013-07-01

    Three-dimensional excitation emission matrix (3DEEM) fluorescence spectroscopy was employed to investigate the structure and characteristics of humic acid (HA) from landfills at different stabilization processes. The results show that the HA in anaerobic landfill leachate stabilized more rapidly than that in semi-aerobic landfill leachate. There were strong interactions between HA and Hg, the S content as well as the oxygen-containing ligands of the HA played a key role in the complexation with mercury. The higher complexation capacity (CL) and stability constant (logK) of HA from anaerobic landfill leachate implies that it is important to strengthen the control of mercury transportation in anaerobic landfills during the early stabilization process. The logK and CL of HA from semi-aerobic landfill leachate increased with the landfill time indicate that control of leachate Hg contamination in the latter stage is of great significance in semi-aerobic landfills. PMID:23523228

  6. Teaching Aerobic Fitness Concepts.

    ERIC Educational Resources Information Center

    Sander, Allan N.; Ratliffe, Tom

    2002-01-01

    Discusses how to teach aerobic fitness concepts to elementary students. Some of the K-2 activities include location, size, and purpose of the heart and lungs; the exercise pulse; respiration rate; and activities to measure aerobic endurance. Some of the 3-6 activities include: definition of aerobic endurance; heart disease risk factors;…

  7. Low Probability of Initiating nirS Transcription Explains Observed Gas Kinetics and Growth of Bacteria Switching from Aerobic Respiration to Denitrification

    PubMed Central

    Hassan, Junaid; Bergaust, Linda L.; Wheat, I. David; Bakken, Lars R.

    2014-01-01

    In response to impending anoxic conditions, denitrifying bacteria sustain respiratory metabolism by producing enzymes for reducing nitrogen oxyanions/-oxides (NOx) to N2 (denitrification). Since denitrifying bacteria are non-fermentative, the initial production of denitrification proteome depends on energy from aerobic respiration. Thus, if a cell fails to synthesise a minimum of denitrification proteome before O2 is completely exhausted, it will be unable to produce it later due to energy-limitation. Such entrapment in anoxia is recently claimed to be a major phenomenon in batch cultures of the model organism Paracoccus denitrificans on the basis of measured e−-flow rates to O2 and NOx. Here we constructed a dynamic model and explicitly simulated actual kinetics of recruitment of the cells to denitrification to directly and more accurately estimate the recruited fraction (). Transcription of nirS is pivotal for denitrification, for it triggers a cascade of events leading to the synthesis of a full-fledged denitrification proteome. The model is based on the hypothesis that nirS has a low probability (, h−1) of initial transcription, but once initiated, the transcription is greatly enhanced through positive feedback by NO, resulting in the recruitment of the transcribing cell to denitrification. We assume that the recruitment is initiated as [O2] falls below a critical threshold and terminates (assuming energy-limitation) as [O2] exhausts. With  = 0.005 h−1, the model robustly simulates observed denitrification kinetics for a range of culture conditions. The resulting (fraction of the cells recruited to denitrification) falls within 0.038–0.161. In contrast, if the recruitment of the entire population is assumed, the simulated denitrification kinetics deviate grossly from those observed. The phenomenon can be understood as a ‘bet-hedging strategy’: switching to denitrification is a gain if anoxic spell lasts long but is a waste of energy if anoxia

  8. Impact of growth conditions on transport behavior of E. coli

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The aim of this investigation is to determine the effect that growth solution has on cell surface properties and transport behavior of eleven E. coli isolates through saturated porous media. The two growth solutions used were a standard laboratory growth medium (LB) and a dairy manure extract soluti...

  9. A Comparison of Three Conditional Growth Percentile Methods: Student Growth Percentiles, Percentile Rank Residuals, and a Matching Method

    ERIC Educational Resources Information Center

    Wyse, Adam E.; Seo, Dong Gi

    2014-01-01

    This article provides a brief overview and comparison of three conditional growth percentile methods; student growth percentiles, percentile rank residuals, and a nonparametric matching method. These approaches seek to describe student growth in terms of the relative percentile ranking of a student in relationship to students that had the same…

  10. A comparison of the distribution of extracellular proteins produced by the protease-secreting organism Aeromonas salmonicida during aerobic and anaerobic growth.

    PubMed

    Fyfe, L; Coleman, G; Munro, A L

    1986-01-01

    Aeromonas salmonicida was grown aerobically and anaerobically in supplemented 3% (w/v) tryptone soya broth medium for 24 h at 25 degrees C. Although the bacterial density achieved was 4.9 times higher in the aerobic culture, the exoprotein produced per unit of bacterial dry weight was only 1.9 times higher than in the anaerobic culture. However, the protease activity of the exoprotein showed a marked reduction anaerobically, being only one-tenth of that of the exoprotein produced aerobically. This finding was consistent with the differing SDS-PAGE patterns of the extracellular proteins from the two cultures, which also showed marked loss and reinforcement of other, as yet unidentified extracellular products. PMID:3322167

  11. Oligotrophic Bacteria Enhance Algal Growth under Iron-Deficient Conditions

    PubMed Central

    Keshtacher-Liebso..., E.; Hadar, Y.; Chen, Y.

    1995-01-01

    A Halomonas sp., a marine halophilic and oligotrophic bacterium, was grown on exudates of Dunaliella bardawil. The bacteria increased the solubility of Fe, thereby enhancing its availability to the algae. As a result, the algal growth rate increased. Because of these syntrophic relations, growth of the marine alga D. bardawil was facilitated at Fe levels that would otherwise induce Fe deficiency and inhibit algal growth. PMID:16535058

  12. Aerobic rice mechanization: techniques for crop establishment

    NASA Astrophysics Data System (ADS)

    Khusairy, K. M.; Ayob, H.; Chan, C. S.; Fauzi, M. I. Mohamed; Mohamad Fakhrul, Z. O.; Shahril Shah, G. S. M.; Azlan, O.; Rasad, M. A.; Hashim, A. M.; Arshad, Z.; E, E. Ibrahim; Saifulizan, M. N.

    2015-12-01

    Rice being the staple food crops, hundreds of land races in it makes the diversity of rice crops. Aerobic rice production was introduced which requires much less water input to safeguard and sustain the rice production and conserve water due to decreasing water resources, climatic changes and competition from urban and industrial users. Mechanization system plays an important role for the success of aerobic rice cultivation. All farming activities for aerobic rice production are run on aerobic soil conditions. Row seeder mechanization system is developed to replace conventional seeding technique on the aerobic rice field. It is targeted for small and the large scale aerobic rice farmers. The aero - seeder machine is used for the small scale aerobic rice field, while the accord - seeder is used for the large scale aerobic rice field. The use of this mechanization machine can eliminate the tedious and inaccurate seeding operations reduce labour costs and increases work rate. The machine is easy to operate and it can increase crop establishment rate. It reduce missing hill, increasing planting and crop with high yield can be produce. This machine is designed for low costs maintenance and it is easy to dismantle and assemble during maintenance and it is safe to be used.

  13. Effects of hydraulic retention time on aerobic granulation and granule growth kinetics at steady state with a fast start-up strategy.

    PubMed

    Liu, Yong-Qiang; Zhang, Xing; Zhang, Rui; Liu, Wen-Tso; Tay, Joo-Hwa

    2016-01-01

    A hydraulic retention time (HRT) of 4, 6, and 8 h was employed, respectively, in three reactors to study the effects of HRT on granulation with a newly developed fast granulation strategy, i.e., a strategy by combining strong hydraulic selection pressure with high organic loading rate (OLR). Granules with clear boundary appeared within 24 h after reactor start-up and all reactors reached a pseudo steady state after 6-day operation. A 4-h HRT resulted in a relatively higher increasing rate in terms of granule size during granule development period, i.e., 208 μm day(-1), and the bigger granule size and the higher sludge volume index at the pseudo steady state. For HRT of 6 or 8 h, no obvious difference was observed. However, it was found that HRT influenced sludge retention time (SRT) and kinetics significantly. A HRT changing from 4 to 8 h led to an increased SRT from 3 to 21 days, a decreased observed specific biomass growth rate (μ obs) and an decreased observed biomass yield (Y obs) of stable granules from 0.37 to 0.062 days(-1), and 0.177 to 0.055 g MLVSS g(-1) COD, respectively. Both μ obs and Y obs had a linear relationship with the reciprocal of HRT. In addition, the great difference of microbial community between seed sludge, sludge retained in the reactors, and sludge washed out indicated a strong microbial selection for fast granulation within 24 h. However, during the granule development period from day 1 to 6, no more microbial selection was observed except an adjustment of microbial community. Little influence of HRT on microbial population in granular sludge indicated a minor role of HRT played for granulation with the fast start-up strategy adopted in this study. The results demonstrated that hydraulic selection pressure for granulation was mainly from short settling time, which led to strong microbial selection during the granulation period. Meanwhile, although HRT did not affect granulation with the fast start-up strategy, it played an

  14. Signaling through the Phosphatidylinositol 3-Kinase (PI3K)/Mammalian Target of Rapamycin (mTOR) Axis Is Responsible for Aerobic Glycolysis mediated by Glucose Transporter in Epidermal Growth Factor Receptor (EGFR)-mutated Lung Adenocarcinoma*

    PubMed Central

    Makinoshima, Hideki; Takita, Masahiro; Saruwatari, Koichi; Umemura, Shigeki; Obata, Yuuki; Ishii, Genichiro; Matsumoto, Shingo; Sugiyama, Eri; Ochiai, Atsushi; Abe, Ryo; Goto, Koichi; Esumi, Hiroyasu; Tsuchihara, Katsuya

    2015-01-01

    Oncogenic epidermal growth factor receptor (EGFR) signaling plays an important role in regulating global metabolic pathways, including aerobic glycolysis, the pentose phosphate pathway (PPP), and pyrimidine biosynthesis. However, the molecular mechanism by which EGFR signaling regulates cancer cell metabolism is still unclear. To elucidate how EGFR signaling is linked to metabolic activity, we investigated the involvement of the RAS/MEK/ERK and PI3K/AKT/mammalian target of rapamycin (mTOR) pathways on metabolic alteration in lung adenocarcinoma (LAD) cell lines with activating EGFR mutations. Although MEK inhibition did not alter lactate production and the extracellular acidification rate, PI3K/mTOR inhibitors significantly suppressed glycolysis in EGFR-mutant LAD cells. Moreover, a comprehensive metabolomics analysis revealed that the levels of glucose 6-phosphate and 6-phosphogluconate as early metabolites in glycolysis and PPP were decreased after inhibition of the PI3K/AKT/mTOR pathway, suggesting a link between PI3K signaling and the proper function of glucose transporters or hexokinases in glycolysis. Indeed, PI3K/mTOR inhibition effectively suppressed membrane localization of facilitative glucose transporter 1 (GLUT1), which, instead, accumulated in the cytoplasm. Finally, aerobic glycolysis and cell proliferation were down-regulated when GLUT1 gene expression was suppressed by RNAi. Taken together, these results suggest that PI3K/AKT/mTOR signaling is indispensable for the regulation of aerobic glycolysis in EGFR-mutated LAD cells. PMID:26023239

  15. Control of the growth of Microthrix parvicelle by using an aerobic selector--results of pilot and full scale plant operation.

    PubMed

    Lebek, M; Rosenwinkel, K H

    2002-01-01

    A two-stage wastewater treatment plant experiences bulking sludge problems in winter, correlating with Microthixparvicella abundance. Pilot and full-scale studies of the use of an aerobic selector to control M. parvicella had little success, probably resulting from long chain fatty acid retention in foam at the tank surface. Initial pilot studies with reduced foam retention showed better results. PMID:12216674

  16. Characterization and aerobic biodegradation of selected monoterpenes

    SciTech Connect

    Misra, G.; Pavlostathis, S.G.; Li, J.; Purdue, E.M.

    1996-12-31

    Monoterpenes are biogenic chemicals and occur in abundance in nature. Large-scale industrial use of these chemicals has recently been initiated in an attempt to replace halogenated solvents and chlorofluorocarbons which have been implicated in the stratospheric depletion of ozone. This study examined four hydrocarbon monoterpenes (d-limonene, {alpha}-pinene, {gamma}-terpinene, and terpinolene) and four alcohols (arbanol, linalool, plinol, and {alpha}-terpineol). Water solubility, vapor pressure, and octanol/water partition coefficients were estimated. Aerobic biodegradability tests were conducted in batch reactors by utilizing forest soil extract and enriched cultures as inoculum. The hydrophobic nature and high volatility of the hydrocarbons restricted the investigation to relatively low aqueous concentrations. Each monoterpene was analyzed with a gas chromatograph equipped with a flame ionization detector after extraction from the aqueous phase with isooctane. Terpene mineralization was tested by monitoring liquid-phase carbon, CO{sub 2} production and biomass growth. All four hydrocarbons and two alcohols readily degraded under aerobic conditions. Plinol resisted degradation in assays using inocula from diverse sources, while arbanol degraded very slowly. The intrinsic biokinetics coefficients for the degradation of d-limonene and {alpha}-terpineol were estimated by using cultures enriched with the respective monoterpenes. Monoterpene biodegradation followed Monod kinetics.

  17. Characterization of a marine origin aerobic nitrifying-denitrifying bacterium.

    PubMed

    Zheng, Hai-Yan; Liu, Ying; Gao, Xi-Yan; Ai, Guo-Min; Miao, Li-Li; Liu, Zhi-Pei

    2012-07-01

    The bacterial strain F6 was isolated from a biological aerated filter that is used for purifying recirculating water in a marine aquaculture system and was identified as Marinobacter sp. based on the analysis of its 16S rRNA gene sequence. Strain F6 showed efficient aerobic denitrifying ability. One hundred percent of nitrates and 73.10% of nitrites were removed, and the total nitrogen (TN) removal rates reached 50.08% and 33.03% under a high nitrate and nitrite concentration in the medium, respectively. N(2)O and (15)N(2), as revealed by GC-MS and GC-IRMS, were the products of aerobic denitrification. Factors affecting the growth and aerobic denitrifying performance of strain F6 were investigated. The results showed that the optimum aerobic denitrification conditions for strain F6 were the presence of sodium succinate as a carbon source, a C/N ratio of 15, salinity ranging from 32-35 g/L of NaCl, incubation temperature of 30°C, an initial pH of 7.5, and rotation speed of 150 rpm [dissolved oxygen (DO) 6.75 mg/L]. In addition, strain F6 was confirmed to be a heterotrophic nitrifier through its NO(2)(-) generation and 25.96% TN removal when NH(4)(+) was used as the sole N source. Therefore, strain F6, the first reported member of genus Marinobacter with aerobic heterotrophic nitrifying-denitrifying ability, is an excellent candidate for facilitating simultaneous nitrification and denitrification (SND) in industry and aquaculture wastewater. PMID:22578593

  18. Deformation and crack growth response under cyclic creep conditions

    SciTech Connect

    Brust, F.W. Jr.

    1995-12-31

    To increase energy efficiency, new plants must operate at higher and higher temperatures. Moreover, power generation equipment continues to age and is being used far beyond its intended original design life. Some recent failures which unfortunately occurred with serious consequences have clearly illustrated that current methods for insuring safety and reliability of high temperature equipment is inadequate. Because of these concerns, an understanding of the high-temperature crack growth process is very important and has led to the following studies of the high temperature failure process. This effort summarizes the results of some recent studies which investigate the phenomenon of high temperature creep fatigue crack growth. Experimental results which detail the process of creep fatigue, analytical studies which investigate why current methods are ineffective, and finally, a new approach which is based on the T{sup *}-integral and its ability to characterize the creep-fatigue crack growth process are discussed. The potential validity of this new predictive methodology is illustrated.

  19. Aerobic microbial enhanced oil recovery

    SciTech Connect

    Torsvik, T.; Gilje, E.; Sunde, E.

    1995-12-31

    In aerobic MEOR, the ability of oil-degrading bacteria to mobilize oil is used to increase oil recovery. In this process, oxygen and mineral nutrients are injected into the oil reservoir in order to stimulate growth of aerobic oil-degrading bacteria in the reservoir. Experiments carried out in a model sandstone with stock tank oil and bacteria isolated from offshore wells showed that residual oil saturation was lowered from 27% to 3%. The process was time dependent, not pore volume dependent. During MEOR flooding, the relative permeability of water was lowered. Oxygen and active bacteria were needed for the process to take place. Maximum efficiency was reached at low oxygen concentrations, approximately 1 mg O{sub 2}/liter.

  20. Correlating electrical resistance to growth conditions for multiwalled carbon nanotubes

    SciTech Connect

    Lan, Chun; Amama, Placidus B.; Fisher, Timothy S.; Reifenberger, Ronald G.

    2007-08-27

    A correlation between growth temperature and electrical resistance of multiwalled carbon nanotubes (MWNTs) has been established by measuring the resistance of individual MWNTs grown by microwave plasma-enhanced chemical vapor deposition (PECVD) at 800, 900, and 950 deg. C. The lowest resistances were obtained mainly from MWNTs grown at 900 deg. C. The MWNT resistance is larger on average at lower (800 deg. C) and higher (950 deg. C) growth temperatures. The resistance of MWNTs correlated well with other MWNT quality indices obtained from Raman spectra. This study identifies a temperature window for growing higher-quality MWNTs with fewer defects and lower resistance by PECVD.

  1. Correlating electrical resistance to growth conditions for multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Lan, Chun; Amama, Placidus B.; Fisher, Timothy S.; Reifenberger, Ronald G.

    2007-08-01

    A correlation between growth temperature and electrical resistance of multiwalled carbon nanotubes (MWNTs) has been established by measuring the resistance of individual MWNTs grown by microwave plasma-enhanced chemical vapor deposition (PECVD) at 800, 900, and 950°C. The lowest resistances were obtained mainly from MWNTs grown at 900°C. The MWNT resistance is larger on average at lower (800°C) and higher (950°C) growth temperatures. The resistance of MWNTs correlated well with other MWNT quality indices obtained from Raman spectra. This study identifies a temperature window for growing higher-quality MWNTs with fewer defects and lower resistance by PECVD.

  2. Green synthesis of Pd/CuO nanoparticles by Theobroma cacao L. seeds extract and their catalytic performance for the reduction of 4-nitrophenol and phosphine-free Heck coupling reaction under aerobic conditions.

    PubMed

    Nasrollahzadeh, Mahmoud; Sajadi, S Mohammad; Rostami-Vartooni, Akbar; Bagherzadeh, Mojtaba

    2015-06-15

    We report the green synthesis of palladium/CuO nanoparticles (Pd/CuO NPs) using Theobroma cacao L. seeds extract and their catalytic activity for the reduction of 4-nitrophenol and Heck coupling reaction under aerobic conditions. The catalyst was characterized using the powder XRD, TEM, EDS, UV-vis and FT-IR. This method has the advantages of high yields, elimination of surfactant, ligand and homogeneous catalysts, simple methodology and easy work up. The catalyst can be recovered from the reaction mixture and reused several times without any significant loss of catalytic activity. PMID:25721860

  3. Formation of filamentous aerobic granules: role of pH and mechanism.

    PubMed

    Wan, Chunli; Yang, Xue; Lee, Duu-Jong; Zhang, Qinlan; Li, Jieni; Liu, Xiang

    2014-10-01

    Filamentous overgrowth in aerobic granular sludge processes can cause reactor failure. In this work, aerobic granules were cultivated in five identical sequencing batch reactors with acetate or glucose as the carbon source with various values of influent pH (4.5-8). Microscopic observations revealed that acidic pH, rather than the species of carbon source, epistatically controls the aerobic granules with filamentous structure. An acidic pH shifted the structure of the microbial community in the granules, such that the fungus Geotrichum fragrans was the predominant filamentous microorganism therein. The acidic pH reduced the intracellular cyclic diguanylate (c-di-GMP) content for increasing the motility of the bacteria to washout and increase the growth rate of G. fragrans on glucose or acetate, together causing overgrowth of the fungus. Maintaining the suspension under alkaline condition is proposed as an effective way to suppress filamentous overgrowth and maintain granule stability. PMID:24928656

  4. Cytotoxic Potential of Bacillus cereus Strains ATCC 11778 and 14579 Against Human Lung Epithelial Cells Under Microaerobic Growth Conditions.

    PubMed

    Kilcullen, Kathleen; Teunis, Allison; Popova, Taissia G; Popov, Serguei G

    2016-01-01

    Bacillus cereus, a food poisoning bacterium closely related to Bacillus anthracis, secretes a multitude of virulence factors including enterotoxins, hemolysins, and phospholipases. However, the majority of the in vitro experiments evaluating the cytotoxic potential of B. cereus were carried out in the conditions of aeration, and the impact of the oxygen limitation in conditions encountered by the microbe in natural environment such as gastrointestinal tract remains poorly understood. This research reports comparative analysis of ATCC strains 11778 (BC1) and 14579 (BC2) in aerobic and microaerobic (static) cultures with regard to their toxicity for human lung epithelial cells. We showed that BC1 increased its toxicity upon oxygen limitation while BC2 was highly cytotoxic in both growth conditions. The combined effect of the pore-forming, cholesterol-dependent hemolysin, cereolysin O (CLO), and metabolic product(s) such as succinate produced in microaerobic conditions provided substantial contribution to the toxicity of BC1 but not BC2 which relied mainly on other toxins. This mechanism is shared between CB1 and B. anthracis. It involves the permeabilization of the cell membrane which facilitates transport of toxic bacterial metabolites into the cell. The toxicity of BC1 was potentiated in the presence of bovine serum albumin which appeared to serve as reservoir for bacteria-derived nitric oxide participating in the downstream production of reactive oxidizing species with the properties of peroxynitrite. In agreement with this the BC1 cultures demonstrated the increased oxidation of the indicator dye Amplex Red catalyzed by peroxidase as well as the increased toxicity in the presence of externally added ascorbic acid. PMID:26870026

  5. Cytotoxic Potential of Bacillus cereus Strains ATCC 11778 and 14579 Against Human Lung Epithelial Cells Under Microaerobic Growth Conditions

    PubMed Central

    Kilcullen, Kathleen; Teunis, Allison; Popova, Taissia G.; Popov, Serguei G.

    2016-01-01

    Bacillus cereus, a food poisoning bacterium closely related to Bacillus anthracis, secretes a multitude of virulence factors including enterotoxins, hemolysins, and phospholipases. However, the majority of the in vitro experiments evaluating the cytotoxic potential of B. cereus were carried out in the conditions of aeration, and the impact of the oxygen limitation in conditions encountered by the microbe in natural environment such as gastrointestinal tract remains poorly understood. This research reports comparative analysis of ATCC strains 11778 (BC1) and 14579 (BC2) in aerobic and microaerobic (static) cultures with regard to their toxicity for human lung epithelial cells. We showed that BC1 increased its toxicity upon oxygen limitation while BC2 was highly cytotoxic in both growth conditions. The combined effect of the pore-forming, cholesterol-dependent hemolysin, cereolysin O (CLO), and metabolic product(s) such as succinate produced in microaerobic conditions provided substantial contribution to the toxicity of BC1 but not BC2 which relied mainly on other toxins. This mechanism is shared between CB1 and B. anthracis. It involves the permeabilization of the cell membrane which facilitates transport of toxic bacterial metabolites into the cell. The toxicity of BC1 was potentiated in the presence of bovine serum albumin which appeared to serve as reservoir for bacteria-derived nitric oxide participating in the downstream production of reactive oxidizing species with the properties of peroxynitrite. In agreement with this the BC1 cultures demonstrated the increased oxidation of the indicator dye Amplex Red catalyzed by peroxidase as well as the increased toxicity in the presence of externally added ascorbic acid. PMID:26870026

  6. Conditions for super-adiabatic droplet growth after entrainment mixing

    NASA Astrophysics Data System (ADS)

    Yang, Fan; Shaw, Raymond; Xue, Huiwen

    2016-07-01

    Cloud droplet response to entrainment and mixing between a cloud and its environment is considered, accounting for subsequent droplet growth during adiabatic ascent following a mixing event. The vertical profile for liquid water mixing ratio after a mixing event is derived analytically, allowing the reduction to be predicted from the mixing fraction and from the temperature and humidity for both the cloud and environment. It is derived for the limit of homogeneous mixing. The expression leads to a critical height above the mixing level: at the critical height the cloud droplet radius is the same for both mixed and unmixed parcels, and the critical height is independent of the updraft velocity and mixing fraction. Cloud droplets in a mixed parcel are larger than in an unmixed parcel above the critical height, which we refer to as the "super-adiabatic" growth region. Analytical results are confirmed with a bin microphysics cloud model. Using the model, we explore the effects of updraft velocity, aerosol source in the environmental air, and polydisperse cloud droplets. Results show that the mixed parcel is more likely to reach the super-adiabatic growth region when the environmental air is humid and clean. It is also confirmed that the analytical predictions are matched by the volume-mean cloud droplet radius for polydisperse size distributions. The findings have implications for the origin of large cloud droplets that may contribute to onset of collision-coalescence in warm clouds.

  7. Conditions for super-adiabatic droplet growth after entrainment mixing

    DOE PAGESBeta

    Yang, Fan; Shaw, Raymond; Xue, Huiwen

    2016-07-29

    Cloud droplet response to entrainment and mixing between a cloud and its environment is considered, accounting for subsequent droplet growth during adiabatic ascent following a mixing event. The vertical profile for liquid water mixing ratio after a mixing event is derived analytically, allowing the reduction to be predicted from the mixing fraction and from the temperature and humidity for both the cloud and environment. It is derived for the limit of homogeneous mixing. The expression leads to a critical height above the mixing level: at the critical height the cloud droplet radius is the same for both mixed and unmixedmore » parcels, and the critical height is independent of the updraft velocity and mixing fraction. Cloud droplets in a mixed parcel are larger than in an unmixed parcel above the critical height, which we refer to as the “super-adiabatic” growth region. Analytical results are confirmed with a bin microphysics cloud model. Using the model, we explore the effects of updraft velocity, aerosol source in the environmental air, and polydisperse cloud droplets. Results show that the mixed parcel is more likely to reach the super-adiabatic growth region when the environmental air is humid and clean. It is also confirmed that the analytical predictions are matched by the volume-mean cloud droplet radius for polydisperse size distributions. The findings have implications for the origin of large cloud droplets that may contribute to onset of collision–coalescence in warm clouds.« less

  8. Management of aerobic vaginitis.

    PubMed

    Tempera, Gianna; Furneri, Pio Maria

    2010-01-01

    Aerobic vaginitis is a new nonclassifiable pathology that is neither specific vaginitis nor bacterial vaginosis. The diversity of this microbiological peculiarity could also explain several therapeutic failures when patients were treated for infections identified as bacterial vaginosis. The diagnosis 'aerobic vaginitis' is essentially based on microscopic examinations using a phase-contrast microscope (at ×400 magnification). The therapeutic choice for 'aerobic vaginitis' should take into consideration an antibiotic characterized by an intrinsic activity against the majority of bacteria of fecal origin, bactericidal effect and poor/absent interference with the vaginal microbiota. Regarding the therapy for aerobic vaginitis when antimicrobial agents are prescribed, not only the antimicrobial spectrum but also the presumed ecological disturbance on the anaerobic and aerobic vaginal and rectal microbiota should be taken into a consideration. Because of their very low impact on the vaginal microbiota, kanamycin or quinolones are to be considered a good choice for therapy. PMID:21051843

  9. Promoters maintain their relative activity levels under different growth conditions

    PubMed Central

    Keren, Leeat; Zackay, Ora; Lotan-Pompan, Maya; Barenholz, Uri; Dekel, Erez; Sasson, Vered; Aidelberg, Guy; Bren, Anat; Zeevi, Danny; Weinberger, Adina; Alon, Uri; Milo, Ron; Segal, Eran

    2013-01-01

    Most genes change expression levels across conditions, but it is unclear which of these changes represents specific regulation and what determines their quantitative degree. Here, we accurately measured activities of ∼900 S. cerevisiae and ∼1800 E. coli promoters using fluorescent reporters. We show that in both organisms 60–90% of promoters change their expression between conditions by a constant global scaling factor that depends only on the conditions and not on the promoter's identity. Quantifying such global effects allows precise characterization of specific regulation—promoters deviating from the global scale line. These are organized into few functionally related groups that also adhere to scale lines and preserve their relative activities across conditions. Thus, only several scaling factors suffice to accurately describe genome-wide expression profiles across conditions. We present a parameter-free passive resource allocation model that quantitatively accounts for the global scaling factors. It suggests that many changes in expression across conditions result from global effects and not specific regulation, and provides means for quantitative interpretation of expression profiles. PMID:24169404

  10. Promoters maintain their relative activity levels under different growth conditions.

    PubMed

    Keren, Leeat; Zackay, Ora; Lotan-Pompan, Maya; Barenholz, Uri; Dekel, Erez; Sasson, Vered; Aidelberg, Guy; Bren, Anat; Zeevi, Danny; Weinberger, Adina; Alon, Uri; Milo, Ron; Segal, Eran

    2013-01-01

    Most genes change expression levels across conditions, but it is unclear which of these changes represents specific regulation and what determines their quantitative degree. Here, we accurately measured activities of ~900 S. cerevisiae and ~1800 E. coli promoters using fluorescent reporters. We show that in both organisms 60-90% of promoters change their expression between conditions by a constant global scaling factor that depends only on the conditions and not on the promoter's identity. Quantifying such global effects allows precise characterization of specific regulation-promoters deviating from the global scale line. These are organized into few functionally related groups that also adhere to scale lines and preserve their relative activities across conditions. Thus, only several scaling factors suffice to accurately describe genome-wide expression profiles across conditions. We present a parameter-free passive resource allocation model that quantitatively accounts for the global scaling factors. It suggests that many changes in expression across conditions result from global effects and not specific regulation, and provides means for quantitative interpretation of expression profiles. PMID:24169404

  11. Studies on Scenedesmus actus growth. I. Effect of autotrophic and mixotrophic conditions on the growth of scenedesmus acutus

    SciTech Connect

    Shamala, T.R.; Drawert, F.; Leupold, G.

    1982-06-01

    Among sugars, glucose and mannose were found to be the most suitable substrates for mixotrophic growth, uptake of galactose and its influence on growth was negligible, and sucrose and fructose occupied intermediary positions. The optimum temperature for sugar uptake was 30 degrees C both under light and in darkness. Enhancement in the photosynthetic oxygen-evolution rate, based on the utilization of substrates, was foremost in the presence of glucose, followed by mannose, sucrose, and fructose. Industrial by-products such as sugarcane molasses also were utilized to increase the algal growth under mixotrophic conditions. A maximum yield in biomass was obtained subsequent to the combined supply of sugarcane molasses with carbon dioxide to indoor as well as outdoor mixotrophic cultures. Doubling the carbon dioxide supply alone above a certain level, under autotrophic and mixotrophic outdoor conditions, did not produce a pronounced increase in the algal growth rate. The results on autotrophic and mixotrophic growth variations are discussed in this article. (Refs. 36).

  12. Plant Growth and Morphogenesis under Different Gravity Conditions: Relevance to Plant Life in Space.

    PubMed

    Hoson, Takayuki

    2014-01-01

    The growth and morphogenesis of plants are entirely dependent on the gravitational acceleration of earth. Under microgravity conditions in space, these processes are greatly modified. Recent space experiments, in combination with ground-based studies, have shown that elongation growth is stimulated and lateral expansion suppressed in various shoot organs and roots under microgravity conditions. Plant organs also show automorphogenesis in space, which consists of altered growth direction and spontaneous curvature in the dorsiventral (back and front) directions. Changes in cell wall properties are responsible for these modifications of growth and morphogenesis under microgravity conditions. Plants live in space with interesting new sizes and forms. PMID:25370193

  13. Automated Diagnosis Of Conditions In A Plant-Growth Chamber

    NASA Technical Reports Server (NTRS)

    Clinger, Barry R.; Damiano, Alfred L.

    1995-01-01

    Biomass Production Chamber Operations Assistant software and hardware constitute expert system that diagnoses mechanical failures in controlled-environment hydroponic plant-growth chamber and recommends corrective actions to be taken by technicians. Subjects of continuing research directed toward development of highly automated closed life-support systems aboard spacecraft to process animal (including human) and plant wastes into food and oxygen. Uses Microsoft Windows interface to give technicians intuitive, efficient access to critical data. In diagnostic mode, system prompts technician for information. When expert system has enough information, it generates recovery plan.

  14. Growth potential of Salmonella spp. and Listeria monocytogenes in nine types of ready-to-eat vegetables stored at variable temperature conditions during shelf-life.

    PubMed

    Sant'Ana, Anderson S; Barbosa, Matheus S; Destro, Maria Teresa; Landgraf, Mariza; Franco, Bernadette D G M

    2012-06-15

    Growth potential (δ) is defined as the difference between the population of a microorganism at the end of shelf-life of specific food and its initial population. The determination of δ of Salmonella and Listeria monocytogenes in RTE vegetables can be very useful to determine likely threats to food safety. However, little is known on the behavior of these microorganisms in several RTE vegetables. Therefore, the aim of this study was to determine the δ of both pathogens in nine different types of RTE vegetables (escarole, collard green, spinach, watercress, arugula, grated carrot, green salad, and mix for yakisoba) stored at refrigeration (7°C) and abuse temperature (15°C). The population of aerobic microorganisms and lactic acid bacteria, including those showing antimicrobial activity has been also determined. Results indicated that L. monocytogenes was able to grow (δ≥0.5 log(10)) in more storage conditions and vegetables than Salmonella. Both microorganisms were inhibited in carrots, although a more pronounced effect has been observed against L. monocytogenes. The highest δ values were obtained when the RTE vegetables were stored 15°C/6days in collard greens (δ=3.3) and arugula (δ=3.2) (L. monocytogenes) and arugula (δ=4.1) and escarole (δ=2.8) (Salmonella). In most vegetables and storage conditions studied, the counts of total aerobic microorganisms raised significantly independent of the temperature of storage (p<0.05). Counts of lactic acid bacteria were higher in vegetables partially or fully stored at abuse temperature with recovery of isolates showing antimicrobial activity. In conclusion, the results of this study show that Salmonella and L. monocytogenes may grow and reach high populations in RTE vegetables depending on storage conditions and the definition of effective intervention strategies are needed to control their growth in these products. PMID:22561064

  15. Graphene growth on SiC(000-1): optimization of surface preparation and growth conditions

    NASA Astrophysics Data System (ADS)

    Robinson, Zachary R.; Jernigan, Glenn G.; Bussmann, Konrad M.; Nyakiti, Luke O.; Garces, Nelson Y.; Nath, Anindya; Wheeler, Virginia D.; Myers-Ward, Rachael L.; Gaskill, D. K.; Eddy, Charles R.

    2015-09-01

    Graphene growth of high crystal quality and single-layer thickness can be achieved by low pressure sublimation (LPS) on SiC(0001). On SiC(0001), which is the C-terminated polar surface, there has been much less success growing uniform, single-layer films. In this work, a systematic study of surface preparation by hydrogen etching followed by LPS in an argon ambient was performed. Hydrogen etching is an important first step in the graphene growth process because it removes damage caused by polishing the substrate surface. However, for SiC(0001), etching at too high of a temperature or for too long has been found to result in pit formation due to the preferential etching of screw dislocations that intersect the surface. It was found that temperatures above 1450°C in 200mbar of hydrogen result in pitting of the surface, whereas etch temperatures at and below 1450°C can result in atomically at terraces of ~ 1 µm width. Following the hydrogen etch optimization, argon-mediated graphene growth was carried out at several different temperatures. For the growth experiments, pressure and growth time were both fixed. Regardless of growth temperature, all of the films were found to have non-uniform thickness. Further, x-ray photoelectron spectroscopy and low energy electron diffraction measurements reveal that trace amounts of oxygen, which may be present during growth, significantly affects the graphene growth process on this polar surface.

  16. Performing Comparative Peptidomics Analyses of Salmonella from Different Growth Conditions

    SciTech Connect

    Adkins, Joshua N.; Mottaz, Heather; Metz, Thomas O.; Ansong, Charles K.; Manes, Nathan P.; Smith, Richard D.; Heffron, Fred

    2010-01-08

    Host–pathogen interactions are complex competitions during which both the host and the pathogen adapt rapidly to each other in order for one or the other to survive. Salmonella enterica serovar Typhimurium is a pathogen with a broad host range that causes a typhoid fever-like disease in mice and severe food poisoning in humans. The murine typhoid fever is a systemic infection in which S.typhimurium evades part of the immune system by replicating inside macrophages and other cells. The transition from a foodborne contaminant to an intracellular pathogen must occur rapidly in multiple,ordered steps in order for S. typhimurium to thrive within its host environment. Using S. typhimurium isolated from rich culture conditions and from conditions that mimic the hostile intracellular environment of the host cell, a native low molecular weight protein fraction, or peptidome, was enriched from cell lysates by precipitation with organic solvents. The enriched peptidome was analyzed by both LC–MS/MS and LC–MS-based methods, although several other methods are possible. Pre-fractionation of peptides allowed identification of small proteins and protein degradation products that would normally be overlooked. Comparison of peptides present in lysates prepared from Salmonella grown under different conditions provided a unique insight into cellular degradation processes as well as identification of novel peptides encoded in the genome but not annotated. The overall approach is detailed here as applied to Salmonella and is adaptable to a broad range of biological systems.

  17. Effect and behaviour of different substrates in relation to the formation of aerobic granular sludge.

    PubMed

    Pronk, M; Abbas, B; Al-Zuhairy, S H K; Kraan, R; Kleerebezem, R; van Loosdrecht, M C M

    2015-06-01

    When aerobic granular sludge is applied for industrial wastewater treatment, different soluble substrates can be present. For stable granular sludge formation on volatile fatty acids (e.g. acetate), production of storage polymers under anaerobic feeding conditions has been shown to be important. This prevents direct aerobic growth on readily available chemical oxygen demand (COD), which is thought to result in unstable granule formation. Here, we investigate the impact of acetate, methanol, butanol, propanol, propionaldehyde, and valeraldehyde on granular sludge formation at 35 °C. Methanogenic archaea, growing on methanol, were present in the aerobic granular sludge system. Methanol was completely converted to methane and carbon dioxide by the methanogenic archaeum Methanomethylovorans uponensis during the 1-h anaerobic feeding period, despite the relative high dissolved oxygen concentration (3.5 mg O2 L(-1)) during the subsequent 2-h aeration period. Propionaldehyde and valeraldehyde were fully disproportionated anaerobically into their corresponding carboxylic acids and alcohols. The organic acids produced were converted to storage polymers, while the alcohols (produced and from influent) were absorbed onto the granular sludge matrix and converted aerobically. Our observations show that easy biodegradable substrates not converted anaerobically into storage polymers could lead to unstable granular sludge formation. However, when the easy biodegradable COD is absorbed in the granules and/or when the substrate is converted by relatively slow growing bacteria in the aerobic period, stable granulation can occur. PMID:25616527

  18. Evaluation of condition indices for estimation of growth of largemouth bass and white crappie

    USGS Publications Warehouse

    Gutreuter, Steve; Childress, W. Michael

    1990-01-01

    We evaluated the ability of three condition indices-condition factor (K), relative condition (Kn), and relative weight (Wr)-to estimate annual growth rates of largemouth bass Micropterus salmoides and white crappies Pomoxis annularis collected during standardized autumn electrofishing and trap-net surveys of Texas reservoirs. Multiple-regression models for estimation of length increments from initial length (at the start of the growing season) and condition indices had R2 values of 0.63-0.76 for largemouth bass and 0.46-0.83 for white crappie. However, these models are not useful for indirect estimation ofgrowth rates because growth must be known (initial length equals length at capture minus estimated annual growth). Models based on length at capture and condition indices had R2 values of 0.22-0.68 for largemouth bass and less than 0.45 for white crappie. The low precision of models based on length at capture indicates that condition provides a weak basis for indirect estimation of growth rates from Texas reservoirs sampled during autumn and, therefore, is unreliable for detection of size-related growth phenomena such as "stockpiling" (size specific, density-dependent growth depression). Direct estimates of growth rates based on back-calculations or tagging data seem necessary for reliable detection of size-related growth patterns for largemouth bass and white crappies from Texas reservoirs.

  19. Growth of samarskite crystal under microgravity conditions (M-20)

    NASA Technical Reports Server (NTRS)

    Takekawa, S.

    1993-01-01

    The purpose of the experiment was to grow single crystals of samarskite under microgravity conditions by the traveling solvent float zone (TSFZ) method, and to study the phase relations in the samarskite-related systems involving liquid phases by the slow cooling float zone (SCFZ) method. Samarskite is one of the minerals in a metamict state and is composed of Ca, Fe, Y, U, Th, Nb, Ta, O, etc. Alpha-particles radiating from uranium and/or thorium in the samarskite itself has destroyed its original structure without damaging its chemical composition and its external form. Consequently its structure was converted into a vitreous structure.

  20. Heterotrophic ammonium removal characteristics of an aerobic heterotrophic nitrifying-denitrifying bacterium, Providencia rettgeri YL.

    PubMed

    Taylor, Shauna M; He, Yiliang; Zhao, Bin; Huang, Jue

    2009-01-01

    Bacterium Providencia rettgeri YL was found to exhibit an unusual ability to heterotrophically nitrify and aerobically denitrify various concentrations of ammonium (NH4+-N). In order to further understand its removal ability, several experiments were conducted to identify the growth and ammonium removal response at different carbon to nitrogen (C/N) mass ratios, shaking speeds, temperatures, ammonium concentrations and to qualitatively verify the production of nitrogen gas using gas chromatography techniques. Results showed that under optimum conditions (C/N 10, 30 degrees C, 120 r/min), YL can significantly remove low and high concentrations of ammonium within 12 to 48 h of growth, respectively. The nitrification products hydroxylamine (NH2OH), nitrite (NO2(-)) and nitrate (NO3(-)) as well as the denitrification product, nitrogen gas (N2), were detected under completely aerobic conditions. PMID:19999986

  1. Carbon Nanotubes Growth by CVD in Various Conditions

    NASA Technical Reports Server (NTRS)

    Zhu, S.; Su, C. H.; Cochrane, J. C.; Lehoczky, S. L.; Gorti, S.; Muntele, I.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    Since the superior properties of multi-wall carbon nanotubes (MWCNT could be used in numerous devices such as electronics and sensors, many efforts have been engaged in synthesizing particular structural or dimensional MWCNT. This presentation will illustrate MWCNT synthesized on silicon substrates by thermal CVD. On the substrate, an array of catalysts is coated using sputtering deposition. A thin Ti buffer layer is also coated on some Si substrates prior to depositing catalyst particles. Nickel, cobalt or iron transition metals are used as catalysts for the MWCNT growth. Since the diameter of MWCNT depends on the size of catalyst particles, the catalyst particle size is investigated after annealed at various temperatures. MWCNT are grown on the substrate in the temperature range of 700 to 1000 C and the pressure range of 100 torr to one atmosphere. Methane and hydrogen gases with methane content of 10% to 100% are used for the MWCNT synthesis. Morphology, length and diameter of these MWCNT are determined by scanning electron microscopy and Raman spectroscopy. The detailed results of syntheses and characterizations will be discussed in the presentation.

  2. Teaching Aerobic Lifestyles: New Perspectives.

    ERIC Educational Resources Information Center

    Goodrick, G. Ken; Iammarino, Nicholas K.

    1982-01-01

    New approaches to teaching aerobic life-styles in secondary schools are suggested, focusing on three components: (1) the psychological benefits of aerobic activity; (2) alternative aerobic programs at nonschool locations; and (3) the development of an aerobics curriculum to help maintain an active life-style after graduation. (JN)

  3. Transcriptomic and metabolomic profiling of Zymomonas mobilis during aerobic and anaerobic fermentations

    SciTech Connect

    Yang, Shihui; Tschaplinski, Timothy J; Engle, Nancy L; Carroll, Sue L; Martin, S L.; Davison, Brian H; Palumbo, Anthony Vito; Brown, Steven D

    2009-01-01

    Zymomonas mobilis ZM4 (ZM4) produces near theoretical yields of ethanol with high specific productivity and recombinant strains are able to ferment both C-5 and C-6 sugars. Z. mobilis performs best under anaerobic conditions, but is an aerotolerant organism. However, the genetic and physiological basis of ZM4's response to various stresses is understood poorly. In this study, transcriptomic and metabolomic profiles for ZM4 aerobic and anaerobic fermentations were elucidated by microarray analysis and by high-performance liquid chromatography (HPLC), gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) analyses. In the absence of oxygen, ZM4 consumed glucose more rapidly, had a higher growth rate, and ethanol was the major end-product. Greater amounts of other end-products such as acetate, lactate, and acetoin were detected under aerobic conditions and at 26 h there was only 1.7% of the amount of ethanol present aerobically as there was anaerobically. In the early exponential growth phase, significant differences in gene expression were not observed between aerobic and anaerobic conditions via microarray analysis. HPLC and GC analyses revealed minor differences in extracellular metabolite profiles at the corresponding early exponential phase time point. Differences in extracellular metabolite profiles between conditions became greater as the fermentations progressed. GC-MS analysis of stationary phase intracellular metabolites indicated that ZM4 contained lower levels of amino acids such as alanine, valine and lysine, and other metabolites like lactate, ribitol, and 4-hydroxybutanoate under anaerobic conditions relative to aerobic conditions. Stationary phase microarray analysis revealed that 166 genes were significantly differentially expressed by more than two-fold. Transcripts for Entner-Doudoroff (ED) pathway genes (glk, zwf, pgl, pgk, and eno) and gene pdc, encoding a key enzyme leading to ethanol production, were at least 30-fold more

  4. Aerobic Reduction of Arsenate by a Bacterium Isolated From Activated Sludge

    NASA Astrophysics Data System (ADS)

    Kozai, N.; Ohnuki, T.; Hanada, S.; Nakamura, K.; Francis, A. J.

    2006-12-01

    Microlunatus phosphovorus strain NM-1 is a polyphosphate-accumulating bacterium isolated from activated sludge. This bacterium takes up a large amount of polyphosphate under aerobic conditions and release phosphate ions by hydrolysis of polyphosphate to orthophosphate under anaerobic conditions to derive energy for taking up substrates. To understand the nature of this strain, especially, influence of potential contaminants in sewage and wastewater on growth, we have been investigating behavior of this bacterium in media containing arsenic. The present paper mainly reports reduction of arsenate by this bacterium under aerobic conditions. The strain NM-1 (JCM 9379) was aerobically cultured at 30 °C in a nutrient medium containing 2.5 g/l peptone, 0.5 g/l glucose, 1.5 g/l yeast extract, and arsenic [Na2HAsO4 (As(V)) or Na3AsO3 (As(III))] at concentrations between 0 and 50 mM. The cells collected from arsenic-free media were dispersed in buffer solutions containing 2mM HEPES, 10mM NaCl, prescribed concentrations of As(V), and 0-0.2 percent glucose. Then, this cell suspension was kept at 20 °C under aerobic or anaerobic conditions. The speciation of arsenic was carried out by ion chromatography and ICP-MS. The growth of the strain under aerobic conditions was enhanced by the addition of As(V) at the concentration between 1 and 10 mM. The maximum optical density of the culture in the medium containing 5mM As(V) was 1.4 times greater than that of the control culture. Below the As(V) concentration of 10mM, most of the As(V) was reduced to As(III). The growth of the strain under anaerobic conditions has not been observed so far. The cells in the buffer solutions reduced As(V) under aerobic condition. The reduction was enhanced by the addition of glucose. However, the cell did not reduce As(V) under anaerobic conditions. The strain NM-1 showed high resistance to As(V) and As(III). The maximum optical density of the culture grown in a medium containing 50 mM As(V) was only

  5. Transcriptomic and metabolomic profiling of Zymomonas mobilis during aerobic and anaerobic fermentations

    PubMed Central

    Yang, Shihui; Tschaplinski, Timothy J; Engle, Nancy L; Carroll, Sue L; Martin, Stanton L; Davison, Brian H; Palumbo, Anthony V; Rodriguez, Miguel; Brown, Steven D

    2009-01-01

    Background Zymomonas mobilis ZM4 (ZM4) produces near theoretical yields of ethanol with high specific productivity and recombinant strains are able to ferment both C-5 and C-6 sugars. Z. mobilis performs best under anaerobic conditions, but is an aerotolerant organism. However, the genetic and physiological basis of ZM4's response to various stresses is understood poorly. Results In this study, transcriptomic and metabolomic profiles for ZM4 aerobic and anaerobic fermentations were elucidated by microarray analysis and by high-performance liquid chromatography (HPLC), gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) analyses. In the absence of oxygen, ZM4 consumed glucose more rapidly, had a higher growth rate, and ethanol was the major end-product. Greater amounts of other end-products such as acetate, lactate, and acetoin were detected under aerobic conditions and at 26 h there was only 1.7% of the amount of ethanol present aerobically as there was anaerobically. In the early exponential growth phase, significant differences in gene expression were not observed between aerobic and anaerobic conditions via microarray analysis. HPLC and GC analyses revealed minor differences in extracellular metabolite profiles at the corresponding early exponential phase time point. Differences in extracellular metabolite profiles between conditions became greater as the fermentations progressed. GC-MS analysis of stationary phase intracellular metabolites indicated that ZM4 contained lower levels of amino acids such as alanine, valine and lysine, and other metabolites like lactate, ribitol, and 4-hydroxybutanoate under anaerobic conditions relative to aerobic conditions. Stationary phase microarray analysis revealed that 166 genes were significantly differentially expressed by more than two-fold. Transcripts for Entner-Doudoroff (ED) pathway genes (glk, zwf, pgl, pgk, and eno) and gene pdc, encoding a key enzyme leading to ethanol production, were at least

  6. Sputtered magnesium diboride thin films: Growth conditions and surface morphology

    NASA Astrophysics Data System (ADS)

    O'Brien, April; Villegas, Brendon; Gu, J. Y.

    2009-01-01

    Magnesium diboride (MgB 2) thin films were deposited on C-plane sapphire substrates by sputtering pure B and Mg targets at different substrate temperatures, and were followed by in situ annealing. A systematic study about the effects of the various growth and annealing parameters on the physical properties of MgB 2 thin films showed that the substrate temperature is the most critical factor that determines the superconducting transition temperature ( Tc), while annealing plays a minor role. There was no superconducting transition in the thin films grown at room temperature without post-annealing. The highest Tc of the samples grown at room temperature after the optimized annealing was 22 K. As the temperature of the substrate ( Ts) increased, Tc rose. However, the maximum Ts was limited due to the low magnesium sticking coefficient and thus the Tc value was limited as well. The highest Tc, 29 K, was obtained for the sample deposited at 180 °C, annealed at 620 °C, and was subsequently annealed a second time at 800 °C. Three-dimensional (3D) AFM images clearly demonstrated that the thin films with no transition, or very low Tc, did not have the well-developed MgB 2 grains while the films with higher Tc displayed the well-developed grains and smooth surface. Although the Tc of sputtered MgB 2 films in the current work is lower than that for the bulk and ex situ annealed thin films, this work presents an important step towards the fabrication of MgB 2 heterostructures using rather simple physical vapor deposition method such as sputtering.

  7. A proposed aerobic granules size development scheme for aerobic granulation process.

    PubMed

    Dahalan, Farrah Aini; Abdullah, Norhayati; Yuzir, Ali; Olsson, Gustaf; Salmiati; Hamdzah, Myzairah; Din, Mohd Fadhil Mohd; Ahmad, Siti Aqlima; Khalil, Khalilah Abdul; Anuar, Aznah Nor; Noor, Zainura Zainon; Ujang, Zaini

    2015-04-01

    Aerobic granulation is increasingly used in wastewater treatment due to its unique physical properties and microbial functionalities. Granule size defines the physical properties of granules based on biomass accumulation. This study aims to determine the profile of size development under two physicochemical conditions. Two identical bioreactors namely Rnp and Rp were operated under non-phototrophic and phototrophic conditions, respectively. An illustrative scheme was developed to comprehend the mechanism of size development that delineates the granular size throughout the granulation. Observations on granules' size variation have shown that activated sludge revolutionised into the form of aerobic granules through the increase of biomass concentration in bioreactors which also determined the changes of granule size. Both reactors demonstrated that size transformed in a similar trend when tested with and without illumination. Thus, different types of aerobic granules may increase in size in the same way as recommended in the aerobic granule size development scheme. PMID:25661308

  8. The Regularities of Fatigue Crack Growth in Airframes Elements at Real Operation Conditions

    NASA Astrophysics Data System (ADS)

    Pavelko, Igors; Pavelko, Vitalijs

    The results of analytical and experimental researches concerning predicting of fatigue crack growth in the operating conditions are presented. First of all the main factors causing a fatigue damage initiation and growth are analyzed and divided to two groups. Common conditions of fatigue damage precise predicting are established. The problem of fatigue crack growth at the stresses of variable amplitude was analyzed and an approach of description of this process is performed. Two examples present the efficiency of this approach. Theory of fatigue crack growth indication and the crack growth indicator (CGI) are developed. There is planned and executed a flight experiment using CGI located on two aircraft An-24 and An-26. Results of crack growth in CGI at operational load allowed to evaluate the parameters of generalized Paris-Erdogan law and statistical properties of crack increment per flight.

  9. Engineering of a modular and synthetic phosphoketolase pathway for photosynthetic production of acetone from CO2 in Synechococcus elongatus PCC 7942 under light and aerobic condition.

    PubMed

    Chwa, Jun-Won; Kim, Wook Jin; Sim, Sang Jun; Um, Youngsoon; Woo, Han Min

    2016-08-01

    Capture and conversion of CO2 to valuable chemicals is intended to answer global challenges on environmental issues, climate change and energy security. Engineered cyanobacteria have been enabled to produce industry-relevant chemicals from CO2 . However, the final products from cyanobacteria have often been mixed with fermented metabolites during dark fermentation. In this study, our engineering of Synechococcus elongatus PCC 7942 enabled continuous conversion of CO2 to volatile acetone as sole product. This process occurred during lighted, aerobic culture via both ATP-driven malonyl-CoA synthesis pathway and heterologous phosphoketolase (PHK)-phosphotransacetylase (Pta) pathway. Because of strong correlations between the metabolic pathways of acetate and acetone, supplying the acetyl-CoA directly from CO2 in the engineered strain, led to sole production of acetone (22.48 mg/L ± 1.00) without changing nutritional constraints, and without an anaerobic shift. Our engineered S. elongatus strains, designed for acetone production, could be modified to create biosolar cell factories for sustainable photosynthetic production of acetyl-CoA-derived biochemicals. PMID:26879003

  10. Roles of triosephosphate isomerase and aerobic metabolism in Trypanosoma brucei.

    PubMed Central

    Helfert, S; Estévez, A M; Bakker, B; Michels, P; Clayton, C

    2001-01-01

    Kinetoplastid protozoa compartmentalize the first seven enzymes of glycolysis and two enzymes of glycerol metabolism in a microbody, the glycosome. While in its mammalian host, Trypanosoma brucei depends entirely on glucose for ATP generation. Under aerobic conditions, most of the glucose is metabolized to pyruvate. Aerobic metabolism depends on the activities of glycosomal triosephosphate isomerase and a mitochondrial glycerophosphate oxidase, and on glycerophosphate<-->dihydroxyacetone phosphate exchange across the glycosomal membrane. Using a combination of genetics and computer modelling, we show that triosephosphate isomerase is probably essential for bloodstream trypanosome survival, but not for the insect-dwelling procyclics, which preferentially use amino acids as an energy source. When the enzyme level decreased to about 15% of that of the wild-type, the growth rate was halved. Below this level, a lethal rise in dihydroxyacetone phosphate was predicted. Expression of cytosolic triosephosphate isomerase inhibited cell growth. Attempts to knockout the trypanosome alternative oxidase genes (which are needed for glycerophosphate oxidase activity) were unsuccessful, but when we lowered the level of the corresponding mRNA by expressing a homologous double-stranded RNA, oxygen consumption was reduced fourfold and the rate of trypanosome growth was halved. PMID:11415442

  11. Hexokinase-2-mediated aerobic glycolysis is integral to cerebellar neurogenesis and pathogenesis of medulloblastoma

    PubMed Central

    2013-01-01

    Background While aerobic glycolysis is linked to unconstrained proliferation in cancer, less is known about its physiological role. Why this metabolic program that promotes tumor growth is preserved in the genome has thus been unresolved. We tested the hypothesis that aerobic glycolysis derives from developmental processes that regulate rapid proliferation. Methods We performed an integrated analysis of metabolism and gene expression in cerebellar granule neuron progenitors (CGNPs) with and without Sonic Hedgehog (Shh), their endogenous mitogen. Because our analysis highlighted Hexokinase-2 (Hk2) as a key metabolic regulator induced by Shh, we studied the effect of conditional genetic Hk2 deletion in CGNP development. We then crossed Hk2 conditional knockout mice with transgenic SmoM2 mice that develop spontaneous medulloblastoma and determined changes in SmoM2-driven tumorigenesis. Results We show that Shh and phosphoinositide 3-kinase (PI3K) signaling combine to induce an Hk2-dependent glycolytic phenotype in CGNPs. This phenotype is recapitulated in medulloblastoma, a malignant tumor of CGNP origin. Importantly, cre-mediated ablation of Hk2 abrogated aerobic glycolysis, disrupting CGNP development and Smoothened-induced tumorigenesis. Comparing tumorigenesis in medulloblastoma-prone SmoM2 mice with and without functional Hk2, we demonstrate that loss of aerobic glycolysis reduces the aggressiveness of medulloblastoma, causing tumors to grow as indolent lesions and allowing long-term survival of tumor bearing mice. Conclusions Our investigations demonstrate that aerobic glycolysis in cancer derives from developmental mechanisms that persist in tumorigenesis. Moreover, we demonstrate in a primary tumor model the anti-cancer potential of blocking aerobic glycolysis by targeting Hk2. See commentary article:http://www.biomedcentral.com/1741-7007/11/3 PMID:24280485

  12. Numerical Studies of Fluid Flow in Microgravity Conditions for Confined Crystal Growth

    NASA Astrophysics Data System (ADS)

    Ruiz, Xavier; Ramírez-Piscina, Laureano; Casademunt, Jaume

    2001-03-01

    We study the convective flow induced by residual accelerations in microgravity conditions for different geometric arrangements which are relevant to crystal growth experiments. We consider both constant and oscillating acceleration and focus mostly on the transient relaxation dynamics. Results are relevant to estimate impact of more realistic residual accelerations in crystal growth experiments.

  13. Bacillus spp. from rainforest soil promote plant growth under limited nitrogen conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aims: The aim of this study was to evaluate effects of PGPR (Plant Growth Promoting Rhizobacteria) isolated from rainforest on different plants under limited nitrogen conditions. Methods and Results: Bacterial isolates from a Peruvian rainforest soil were screened for plant growth promoting effects...

  14. Aerobic biodegradation of trichloroethene without auxiliary substrates.

    PubMed

    Schmidt, Kathrin R; Gaza, Sarah; Voropaev, Andrey; Ertl, Siegmund; Tiehm, Andreas

    2014-08-01

    Trichloroethene (TCE) represents a priority pollutant and is among the most frequently detected contaminants in groundwater. The current bioremediation measures have certain drawbacks like e.g. the need for auxiliary substrates. Here, the aerobic biodegradation of TCE as the sole growth substrate is demonstrated. This new process of metabolic TCE degradation was first detected in groundwater samples. TCE degradation was stable in an enriched mixed bacterial culture in mineral salts medium for over five years and repeated transfers of the culture resulting in a 10(10) times dilution of the original groundwater. Aerobic TCE degradation resulted in stoichiometric chloride formation. Stable carbon isotope fractionation was observed providing a reliable analytical tool to assess this new biodegradation process at field sites. The results suggest that aerobic biodegradation of TCE without auxiliary substrate could be considered as an option for natural attenuation or engineered bioremediation of contaminated sites. PMID:24793109

  15. Conditional knockout of Mn-SOD targeted to type IIB skeletal muscle fibers increases oxidative stress and is sufficient to alter aerobic exercise capacity

    PubMed Central

    Lustgarten, Michael S.; Jang, Youngmok C.; Liu, Yuhong; Muller, Florian L.; Qi, Wenbo; Steinhelper, Mark; Brooks, Susan V.; Larkin, Lisa; Shimizu, Takahiko; Shirasawa, Takuji; McManus, Linda M.; Bhattacharya, Arunabh; Richardson, Arlan

    2009-01-01

    In vitro studies of isolated skeletal muscle have shown that oxidative stress is limiting with respect to contractile function. Mitochondria are a potential source of muscle function-limiting oxidants. To test the hypothesis that skeletal muscle-specific mitochondrial oxidative stress is sufficient to limit muscle function, we bred mice expressing Cre recombinase driven by the promoter for the inhibitory subunit of troponin (TnIFast-iCre) with mice containing a floxed Sod2 (Sod2fl/fl) allele. Mn-SOD activity was reduced by 82% in glycolytic (mainly type II) muscle fiber homogenates from young TnIFastCreSod2fl/fl mice. Furthermore, Mn-SOD content was reduced by 70% only in type IIB muscle fibers. Aconitase activity was decreased by 56%, which suggests an increase in mitochondrial matrix superoxide. Mitochondrial superoxide release was elevated more than twofold by mitochondria isolated from glycolytic skeletal muscle in TnIFastCreSod2fl/fl mice. In contrast, the rate of mitochondrial H2O2 production was reduced by 33%, and only during respiration with complex II substrate. F2-isoprostanes were increased by 36% in tibialis anterior muscles isolated from TnIFastCreSod2fl/fl mice. Elevated glycolytic muscle-specific mitochondrial oxidative stress and damage in TnIFastCreSod2fl/fl mice were associated with a decreased ability of the extensor digitorum longus and gastrocnemius muscles to produce contractile force as a function of time, whereas force production by the soleus muscle was unaffected. TnIFastCreSod2fl/fl mice ran 55% less distance on a treadmill than wild-type mice. Collectively, these data suggest that elevated mitochondrial oxidative stress and damage in glycolytic muscle fibers are sufficient to reduce contractile muscle function and aerobic exercise capacity. PMID:19776389

  16. Controlling the catalytic aerobic oxidation of phenols.

    PubMed

    Esguerra, Kenneth Virgel N; Fall, Yacoub; Petitjean, Laurène; Lumb, Jean-Philip

    2014-05-28

    The oxidation of phenols is the subject of extensive investigation, but there are few catalytic aerobic examples that are chemo- and regioselective. Here we describe conditions for the ortho-oxygenation or oxidative coupling of phenols under copper (Cu)-catalyzed aerobic conditions that give rise to ortho-quinones, biphenols or benzoxepines. We demonstrate that each product class can be accessed selectively by the appropriate choice of Cu(I) salt, amine ligand, desiccant and reaction temperature. In addition, we evaluate the effects of substituents on the phenol and demonstrate their influence on selectivity between ortho-oxygenation and oxidative coupling pathways. These results create an important precedent of catalyst control in the catalytic aerobic oxidation of phenols and set the stage for future development of catalytic systems and mechanistic investigations. PMID:24784319

  17. Bacterial Epimerization as a Route for Deoxynivalenol Detoxification: the Influence of Growth and Environmental Conditions.

    PubMed

    He, Jian Wei; Hassan, Yousef I; Perilla, Norma; Li, Xiu-Zhen; Boland, Greg J; Zhou, Ting

    2016-01-01

    Deoxynivalenol (DON) is a toxic secondary metabolite produced by several Fusarium species that infest wheat and corn. Food and feed contaminated with DON pose a health risk to both humans and livestock and form a major barrier for international trade. Microbial detoxification represents an alternative approach to the physical and chemical detoxification methods of DON-contaminated grains. The present study details the characterization of a novel bacterium, Devosia mutans 17-2-E-8, that is capable of transforming DON to a non-toxic stereoisomer, 3-epi-deoxynivalenol under aerobic conditions, mild temperature (25-30°C), and neutral pH. The biotransformation takes place in the presence of rich sources of organic nitrogen and carbon without the need of DON to be the sole carbon source. The process is enzymatic in nature and endures a high detoxification capacity (3 μg DON/h/10(8) cells). The above conditions collectively suggest the possibility of utilizing the isolated bacterium as a feed treatment to address DON contamination under empirical field conditions. PMID:27148248

  18. Bacterial Epimerization as a Route for Deoxynivalenol Detoxification: the Influence of Growth and Environmental Conditions

    PubMed Central

    He, Jian Wei; Hassan, Yousef I.; Perilla, Norma; Li, Xiu-Zhen; Boland, Greg J.; Zhou, Ting

    2016-01-01

    Deoxynivalenol (DON) is a toxic secondary metabolite produced by several Fusarium species that infest wheat and corn. Food and feed contaminated with DON pose a health risk to both humans and livestock and form a major barrier for international trade. Microbial detoxification represents an alternative approach to the physical and chemical detoxification methods of DON-contaminated grains. The present study details the characterization of a novel bacterium, Devosia mutans 17-2-E-8, that is capable of transforming DON to a non-toxic stereoisomer, 3-epi-deoxynivalenol under aerobic conditions, mild temperature (25–30°C), and neutral pH. The biotransformation takes place in the presence of rich sources of organic nitrogen and carbon without the need of DON to be the sole carbon source. The process is enzymatic in nature and endures a high detoxification capacity (3 μg DON/h/108 cells). The above conditions collectively suggest the possibility of utilizing the isolated bacterium as a feed treatment to address DON contamination under empirical field conditions. PMID:27148248

  19. Requirement for terminal cytochromes in generation of the aerobic signal for the arc regulatory system in Escherichia coli: study utilizing deletions and lac fusions of cyo and cyd.

    PubMed Central

    Iuchi, S; Chepuri, V; Fu, H A; Gennis, R B; Lin, E C

    1990-01-01

    Escherichia coli has two terminal oxidases for its respiratory chain: cytochrome o (low O2 affinity) and cytochrome d (high O2 affinity). Expression of the cyo operon, encoding cytochrome o, is decreased by anaerobic growth, whereas expression of the cyd operon, encoding cytochrome d, is increased by anaerobic growth. We show by the use of lac gene fusion that the expressions of cyo and cyd are under the control of the two-component arc system. In a cyo+ cyd+ background, expression of phi(cyo-lac) is higher when the organism is grown aerobically than when it is grown anaerobically. A mutation in either the sensor gene arcB or the pleiotropic regulator gene arcA almost abolishes the anaerobic repression. In the same background, expression of phi(cyd-lac) is higher under anaerobic growth conditions than under aerobic growth conditions. A mutation in arcA or arcB lowers both the aerobic and anaerobic expressions, suggesting that ArcA plays an activating role instead of the typical repressing role. Under aerobic growth conditions, double deletions of cyo and cyd lower phi(cyo-lac) expression but enhance phi(cyd-lac) expression. The double deletions also prevent elevated aerobic induction of the lct operon (encoding L-lactate dehydrogenase), another target operon of the arc system. In contrast, these deletions do not circumvent aerobic repression of the nar operon (encoding the anaerobic respiratory enzyme nitrate reductase) under the control of the pleiotropic fnr gene product. It thus appears that ArcB senses the presence of O2 by level of an electron transport component in reduced form or that of an nonautoxidizable compound linked to the process by a redox reaction, whereas Fnr senses O2 by a different mechanism. PMID:2170337

  20. A water use and growth model for Eucalyptus plantation in water-limited conditions

    SciTech Connect

    Calder, I.R.

    1992-12-31

    To investigate the environmental impact of plantation forestry using fast-growing tree species in southern India, a program of field studies was initiated in 1987 specifically to measure the water use, nutrient uptake and growth rates of the plantations. A water use and growth (WAG) model is proposed for calculating transpiration and growth of Eucalyptus plantation in water-limited conditions. The model is based on the measured relationships between transpiration rate and basal cross-sectional area and soil moisture availability. The volume growth rate (in water-limited conditions) is assumed to be proportional to the volume of water transpired. The model is calibrated using (deuterium tracing) measurements of transpiration and measurements of growth recorded at the Puradal experimental plantation, Karnataka, southern India.

  1. Synthesis of graphene by chemical vapor deposition: effect of growth conditions.

    PubMed

    Su, Dan; Ren, Mingwei; Li, Xing'ao; Huang, Wei

    2013-10-01

    Graphene has attracted a great deal of attention due to its extraordinary physical and chemical properties. But the control of growth of high-quality, large-area and inexpensive graphene is still the bottleneck for practical applications. Chemical vapor deposition (CVD) has become the most common method for graphene growth due to its high production and large area of product. However, it generally suffers from an uncontrollable carbon precipitation effect that leads to inhomogeneous growth and strongly dependent on to the growth conditions. Until now, scientists have struggled to synthesize higher quality, larger area graphene through changing the experimental conditions. In this review, the progress made in the last few years concerning the exploration of preparation graphene by CVD is summarized in three aspects (catalysts, precursors and experimental parameters) that influence graphene growth. PMID:24245104

  2. Tolerance of anaerobic conditions caused by flooding during germination and early growth in rice (Oryza sativa L.).

    PubMed

    Miro, Berta; Ismail, Abdelbagi M

    2013-01-01

    Rice is semi-aquatic, adapted to a wide range of hydrologies, from aerobic soils in uplands to anaerobic and flooded fields in waterlogged lowlands, to even deeply submerged soils in flood-prone areas. Considerable diversity is present in native rice landraces selected by farmers over centuries. Our understanding of the adaptive features of these landraces to native ecosystems has improved considerably over the recent past. In some cases, major genes associated with tolerance have been cloned, such as SUB1A that confers tolerance of complete submergence and SNORKEL genes that control plant elongation to escape deepwater. Modern rice varieties are sensitive to flooding during germination and early growth, a problem commonly encountered in rainfed areas, but few landraces capable of germination under these conditions have recently been identified, enabling research into tolerance mechanisms. Major QTLs were also identified, and are being targeted for molecular breeding and for cloning. Nevertheless, limited progress has been made in identifying regulatory processes for traits that are unique to tolerant genotypes, including faster germination and coleoptile elongation, formation of roots and leaves under hypoxia, ability to catabolize starch into simple sugars for subsequent use in glycolysis and fermentative pathways to generate energy. Here we discuss the state of knowledge on the role of the PDC-ALDH-ACS bypass and the ALDH enzyme as the likely candidates effective in tolerant rice genotypes. Potential involvement of factors such as cytoplasmic pH regulation, phytohormones, reactive oxygen species scavenging and other metabolites is also discussed. Further characterization of contrasting genotypes would help in elucidating the genetic and biochemical regulatory and signaling mechanisms associated with tolerance. This could facilitate breeding rice varieties suitable for direct seeding systems and guide efforts for improving waterlogging tolerance in other crops

  3. Tolerance of anaerobic conditions caused by flooding during germination and early growth in rice (Oryza sativa L.)

    PubMed Central

    Miro, Berta; Ismail, Abdelbagi M.

    2013-01-01

    Rice is semi-aquatic, adapted to a wide range of hydrologies, from aerobic soils in uplands to anaerobic and flooded fields in waterlogged lowlands, to even deeply submerged soils in flood-prone areas. Considerable diversity is present in native rice landraces selected by farmers over centuries. Our understanding of the adaptive features of these landraces to native ecosystems has improved considerably over the recent past. In some cases, major genes associated with tolerance have been cloned, such as SUB1A that confers tolerance of complete submergence and SNORKEL genes that control plant elongation to escape deepwater. Modern rice varieties are sensitive to flooding during germination and early growth, a problem commonly encountered in rainfed areas, but few landraces capable of germination under these conditions have recently been identified, enabling research into tolerance mechanisms. Major QTLs were also identified, and are being targeted for molecular breeding and for cloning. Nevertheless, limited progress has been made in identifying regulatory processes for traits that are unique to tolerant genotypes, including faster germination and coleoptile elongation, formation of roots and leaves under hypoxia, ability to catabolize starch into simple sugars for subsequent use in glycolysis and fermentative pathways to generate energy. Here we discuss the state of knowledge on the role of the PDC-ALDH-ACS bypass and the ALDH enzyme as the likely candidates effective in tolerant rice genotypes. Potential involvement of factors such as cytoplasmic pH regulation, phytohormones, reactive oxygen species scavenging and other metabolites is also discussed. Further characterization of contrasting genotypes would help in elucidating the genetic and biochemical regulatory and signaling mechanisms associated with tolerance. This could facilitate breeding rice varieties suitable for direct seeding systems and guide efforts for improving waterlogging tolerance in other crops

  4. Aminolaevulinate synthetase of Micrococcus denitrificans. Purification and properties of the enzyme, and the effect of growth conditions on the enzyme activity in cells.

    PubMed

    Tait, G H

    1973-02-01

    1. 5-Aminolaevulinate synthetase was detected in extracts of the non-photosynthetic bacterium Micrococcus denitrificans. 2. Activity is high in cells grown anaerobically in a defined nitrate medium, but is low in cells grown in an iron-deficient medium, and in cells grown aerobically. 3. Aminolaevulinate synthetase was purified extensively; it has a molecular weight of about 68000; apparent K(m) values for glycine, succinyl-CoA and pyridoxal phosphate are 12mm, 10mum and 11mum respectively; 2mum-haemin and 14mum-protoporphyrin inhibit by 50%. 4. The low activity of aminolaevulinate synthetase in iron-deficient cells increases on adding iron salts to cells only under conditions where protein synthesis can occur. 5. In defined nitrate medium with a high Ca(2+) concentration anaerobic growth yield is higher, but aminolaevulinate synthetase activity is lower than in cells grown in the medium with a low Ca(2+) concentration. In medium made from AnalaR constituents, growth yield is low and aminolaevulinate synthetase activity is high even in the presence of high concentrations of Ca(2+); on adding Cu(2+) (0.1mum) to the medium growth yield and aminolaevulinate synthetase activity become the same as in non-AnalaR medium. 6. Cells incubated under conditions where protein synthesis does not occur but where electron transport does, lose their aminolaevulinate synthetase activity rapidly. 7. The activities of aminolaevulinate dehydratase and succinic thiokinase do not change under any of the conditions of growth examined. 8. The possible mechanisms controlling aminolaevulinate synthetase activity and the role of this enzyme in controlling the synthesis of haem in this organism are discussed. PMID:4722442

  5. Growth Characteristics of Carbon Nanotubes on Oxidized Catalyst under Low-Pressure Condition

    NASA Astrophysics Data System (ADS)

    Sawaguchi, Daiki; Sato, Hideki; Hata, Koichi; Miyake, Hideto; Iida, Kazuo; Hiramatsu, Kazumasa

    2012-01-01

    Low-pressure alcohol catalytic chemical vapor deposition (LP-ACCVD), which is an ACCVD method at a lower pressure (<1 Pa) than that in the conventional method, has been attracting much interest because it enables the low-temperature growth of single-wall carbon nanotubes (CNTs). However, the growth rate of CNTs by LP-ACCVD is markedly low owing to its low growth pressure. To alleviate this problem, we have examined the influence of the catalyst preparation and CVD conditions on the properties of CNTs grown by LP-ACCVD. It has been found that the oxidation of catalyst enhances the growth of CNTs by LP-ACCVD. Furthermore, the low flow rate of the ethanol enhances the growth yield of CNTs at lower growth temperature, which is understood to be the result of sufficient gas heating on the substrate.

  6. Radiative defects in GaN nanocolumns: Correlation with growth conditions and sample morphology

    SciTech Connect

    Lefebvre, P.; Fernandez-Garrido, S.; Grandal, J.; Ristic, J.; Sanchez-Garcia, M.-A.; Calleja, E.

    2011-02-21

    Low-temperature photoluminescence is studied in detail in GaN nanocolumns (NCs) grown by plasma-assisted molecular beam epitaxy under various conditions (substrate temperature and impinging Ga/N flux ratio). The relative intensities of the different emission lines, in particular those related to structural defects, appear to be correlated with the growth conditions, and clearly linked to the NC sample morphology. We demonstrate, in particular, that all lines comprised between 3.10 and 3.42 eV rapidly lose intensity when the growth conditions are such that the NC coalescence is reduced. The well-known line around 3.45 eV, characteristic of GaN NC samples, shows, however, a behavior that is exactly the opposite of the other lines, namely, for growth conditions leading to reduced NC coalescence, this line tends to become more prominent, thus proving to be intrinsic to individual GaN NCs.

  7. Cadmium removal by Euglena gracilis is enhanced under anaerobic growth conditions.

    PubMed

    Santiago-Martínez, M Geovanni; Lira-Silva, Elizabeth; Encalada, Rusely; Pineda, Erika; Gallardo-Pérez, Juan Carlos; Zepeda-Rodriguez, Armando; Moreno-Sánchez, Rafael; Saavedra, Emma; Jasso-Chávez, Ricardo

    2015-05-15

    The facultative protist Euglena gracilis, a heavy metal hyper-accumulator, was grown under photo-heterotrophic and extreme conditions (acidic pH, anaerobiosis and with Cd(2+)) and biochemically characterized. High biomass (8.5×10(6)cellsmL(-1)) was reached after 10 days of culture. Under anaerobiosis, photosynthetic activity built up a microaerophilic environment of 0.7% O₂, which was sufficient to allow mitochondrial respiratory activity: glutamate and malate were fully consumed, whereas 25-33% of the added glucose was consumed. In anaerobic cells, photosynthesis but not respiration was activated by Cd(2+) which induced higher oxidative stress. Malondialdehyde (MDA) levels were 20 times lower in control cells under anaerobiosis than in aerobiosis, although Cd(2+) induced a higher MDA production. Cd(2+) stress induced increased contents of chelating thiols (cysteine, glutathione and phytochelatins) and polyphosphate. Biosorption (90%) and intracellular accumulation (30%) were the mechanisms by which anaerobic cells removed Cd(2+) from medium, which was 36% higher versus aerobic cells. The present study indicated that E. gracilis has the ability to remove Cd(2+) under anaerobic conditions, which might be advantageous for metal removal in sediments from polluted water bodies or bioreactors, where the O₂ concentration is particularly low. PMID:25698571

  8. Dance--Aerobic and Anaerobic.

    ERIC Educational Resources Information Center

    Cohen, Arlette

    1984-01-01

    This article defines and explains aerobic exercise and its effects on the cardiovascular system. Various studies on dancers are cited indicating that dance is an anaerobic activity with some small degree of aerobic benefit. (DF)

  9. Local weather conditions have complex effects on the growth of blue tit nestlings.

    PubMed

    Mainwaring, Mark C; Hartley, Ian R

    2016-08-01

    Adverse weather conditions are expected to result in impaired nestling development in birds, but empirical studies have provided equivocal support for such a relationship. This may be because the negative effects of adverse weather conditions are masked by parental effects. Globally, ambient temperatures, rainfall levels and wind speeds are all expected to increase in a changing climate and so there is a need for a better understanding of the relationship between weather conditions and nestling growth. Here, we describe a correlative study that examined the relationships between local temperatures, rainfall levels and wind speeds and the growth of individual blue tit (Cyanistes caeruleus) nestlings in relation to their hatching order and sex. We found that changes in a range of morphological characters were negatively related to both temperature and wind speed, but positively related to rainfall. These patterns were further influenced by the hatching order of the nestlings but not by nestling sex. This suggests that the predicted changes in local weather conditions may have complex effects on nestling growth, but that parents may be able to mitigate the adverse effects via adaptive parental effects. We therefore conclude that local weather conditions have complex effects on avian growth and the implications for patterns of avian growth in a changing climate are discussed. PMID:27503711

  10. Extent of fungal growth on fiberglass duct liners with and without biocides under challenging environmental conditions.

    PubMed

    Samimi, Behzad S; Ross, Kristen

    2003-03-01

    Eight brands of fiberglass duct liners, including three that contained biocides, were exposed to challenging environmental conditions that would promote fungal growth. Twenty-four rectangular sheet metal ducts in three groups of eight ducts per group were lined with the eight selected liners. Each group of ducts was exposed to one of the three test conditions within an environmental chamber for a period of 15 days. These conditions were a) 75 percent RH, b) 75 percent RH plus water spray, c) 75 percent RH plus dry nutrient, and d) 75 percent RH plus water plus nutrient. Viable spores of Aspergillus niger were aerosolized into each duct as seed. On the 16th day, air and surface samples for fungal spores were collected from inside ducts. The results of air sampling using N6 sampler and visual inspection indicated that two out of three biocide-containing liners, Permacote and Toughgard, inhibited fungal growth but only under condition A. The third biocide-containing liner, Aeroflex Plus, was effective even when it was wet (conditions A and B). All three biocide-containing liners failed to inhibit fungal growth under conditions C and D. Among the five other types of liners that did not contain biocides, ATCO Flex with a smooth Mylar coating was more preferable, exhibiting lower fungal activity during conditions A, B, and C. All liners failed under condition D when nutrient and water were added together. Surface sampling using adhesive tape failed to produce representative results, apparently due to rough/porous surface of duct liners. It was concluded that duct liners with biocide treatment could be less promoting to microbial growth under high humidity as long as their surfaces remain clean and water-free. A liner with an impermeable and smooth surface seems to be less subject to microbial growth under most conditions than biocide-containing liners having porous and/or rough surfaces. PMID:12573965

  11. Disruption of the lower food web in Lake Ontario: Did it affect alewife growth or condition?

    USGS Publications Warehouse

    O'Gorman, R.; Prindle, S.E.; Lantry, J.R.; Lantry, B.F.

    2008-01-01

    From the early 1980s to the late 1990s, a succession of non-native invertebrates colonized Lake Ontario and the suite of consequences caused by their colonization became known as "food web disruption". For example, the native burrowing amphipod Diporeia spp., a key link in the profundal food web, declined to near absence, exotic predaceous cladocerans with long spines proliferated, altering the zooplankton community, and depth distributions of fishes shifted. These changes had the potential to affect growth and condition of planktivorous alewife Alosa pseudoharengus, the most abundant fish in the lake. To determine if food web disruption affected alewife, we used change-point analysis to examine alewife growth and adult alewife condition during 1976-2006 and analysis-of-variance to determine if values between change points differed significantly. There were no change points in growth during the first year of life. Of three change points in growth during the second year of life, one coincided with the shift in springtime distribution of alewife to deeper water but it was not associated with a significant change in growth. After the second year of life, no change points in growth were evident, although growth in the third year of life spiked in those years when Bythotrephes, the largest of the exotic cladocerans, was abundant suggesting that it was a profitable prey item for age-2 fish. We detected two change points in condition of adult alewife in fall, but the first occurred in 1981, well before disruption began. A second change point occurred in 2003, well after disruption began. After the springtime distribution of alewife shifted deeper during 1992-1994, growth in the first two years of life became more variable, and growth in years of life two and older became correlated (P < 0.05). In conclusion, food web disruption had no negative affect on growth and condition of alewife in Lake Ontario although it appears to have resulted in growth in the first two years of

  12. Intrauterine Growth Retardation (IUGR) as a Novel Condition of Insulin-Like Growth Factor-1 (IGF-1) Deficiency.

    PubMed

    Martín-Estal, I; de la Garza, R G; Castilla-Cortázar, I

    2016-01-01

    Insulin-like growth factor 1 (IGF-1) is an anabolic hormone with several biological activities, such as proliferation, mitochondrial protection, cell survival, tissue growth and development, anti-inflammatory, antioxidant, antifibrogenic and antiaging. This hormone plays an important role in embryological and postnatal states, being essential for normal foetal and placental growth and differentiation. During gestation, the placenta is one of the major sources of IGF-1, among other hormones. This intrauterine organ expresses IGF-1 receptors and IGF-1 binding proteins (IGFBPs), which control IGF-1 activities. Intrauterine growth restriction (IUGR) is the second most frequent cause of perinatal morbidity and mortality, defined as the inability to achieve the expected weight for gestational age. Different studies have revealed that IUGR infants have placental dysfunction and low circulating levels of insulin, IGF-1, IGF-2 and IGFBPs. Such data suggest that IGF-1 deficiency in gestational state may be one of the major causes of foetal growth retardation. The aim of this review is to study the epidemiology, physiopathology and possible causes of IUGR. Also, it intends to study the possible role of the placenta as an IGF-1 target organ. The purpose is to establish if IUGR could be considered as a novel condition of IGF-1 deficiency and if its treatment with low doses of IGF-1 could be a suitable therapeutic strategy. PMID:26634242

  13. Aerobic Dance in Public Schools.

    ERIC Educational Resources Information Center

    Chiles, Barbara Ann; Moore, Suzanne

    1981-01-01

    Aerobic dance offers a challenging workout in a social atmosphere. Though some physical education instructors tend to exclude dance units from the curriculum, most could teach aerobic dance if they had a basic knowledge of aerobic routines. The outline for a unit to be used in the class is presented. (JN)

  14. Managing for Improved Aerobic Stability

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aerobic deterioration or spoilage of silage is the result of aerobic microorganisms metabolizing components of the silage using oxygen. In the almost 40 years over which these silage conferences have been held, we have come to recognize the typical pattern of aerobic microbial development by which s...

  15. Differential sensitivity of aerobic gram-positive and gram-negative microorganisms to 2,4,6-trinitrotoluene (TNT) leads to dissimilar growth and TNT transformation: Results of soil and pure culture studies

    SciTech Connect

    Fuller, M.E.; Manning, J.F. Jr.

    1996-07-30

    The effects of 2,4,6-trinitrotoluene (TNT) on indigenous soil populations and pure bacterial cultures were examined. The number of colony-forming units (CFU) appearing when TNT-contaminated soil was spread on 0.3% molasses plates decreased by 50% when the agar was amended with 67 {mu}g TNT mL{sup -1}, whereas a 99% reduction was observed when uncontaminated soil was plated. Furthermore, TNT-contaminated soil harbored a greater number of organisms able to grow on plates amended with greater than 10 {mu}g TNT mL{sup -1}. The percentage of gram-positive isolates was markedly less in TNT-contaminated soil (7%; 2 of 30) than in uncontaminated soil (61%; 20 of 33). Pseudomonas aeruginosa, Pseudomonas corrugate, Pseudomonasfluorescens and Alcaligenes xylosoxidans made up the majority of the gram-negative isolates from TNT-contaminated soil. Gram-positive isolates from both soils demonstrated marked growth inhibition when greater than 8-16 {mu}g TNT mL{sup -1} was present in the culture media. Most pure cultures of known aerobic gram-negative organisms readily degraded TNT and evidenced net consumption of reduced metabolites. However, pure cultures of aerobic gram-positive bacteria were sensitive to relatively low concentrations of TNT as indicated by the 50% reduction in growth and TNT transformation which was observed at approximately 10 {mu}g TNT mL{sup -1}. Most non-sporeforming gram-positive organisms incubated in molasses media amended with 80 {mu}g TNT mL{sup -1} or greater became unculturable, whereas all strains tested remained culturable when incubated in mineral media amended with 98 {mu}g TNT mL{sup -1}, indicating that TNT sensitivity is likely linked to cell growth. These results indicate that gram-negative organisms are most likely responsible for any TNT transformation in contaminated soil, due to their relative insensitivity to high TNT concentrations and their ability to transform TNT.

  16. Biomass and lipid production of a local isolate Chlorella sorokiniana under mixotrophic growth conditions.

    PubMed

    Juntila, D J; Bautista, M A; Monotilla, W

    2015-09-01

    A local Chlorella sp. isolate with 97% rbcL sequence identity to Chlorella sorokiniana was evaluated in terms of its biomass and lipid production under mixotrophic growth conditions. Glucose-supplemented cultures exhibited increasing growth rate and biomass yield with increasing glucose concentration. Highest growth rate and biomass yield of 1.602 day(-1) and 687.5 mg L(-1), respectively, were achieved under 2 g L(-1) glucose. Nitrogen starvation up to 75% in the 1.0 g L(-1) glucose-supplemented culture was done to induce lipid accumulation and did not significantly affect the growth. Lipid content ranges from 20% to 27% dry weight. Nile Red staining showed more prominent neutral lipid bodies in starved mixotrophic cultures. C. sorokiniana exhibited enhanced biomass production under mixotrophy and more prominent neutral lipid accumulation under nitrogen starvation with no significant decrease in growth; hence, this isolate could be further studied to establish its potential for biodiesel production. PMID:25847795

  17. Effects of different test conditions on MICs of food animal growth-promoting antibacterial agents for enterococci.

    PubMed

    Butaye, P; Devriese, L A; Haesebrouck, F

    1998-07-01

    The influence of the addition of sheep blood to Mueller-Hinton II agar and the effects of aerobic incubation with or without CO2 and of anaerobic incubation were tested with bacitracin, tylosin, avoparcin, virginiamycin, avilamycin, narasin, and flavomycin on enterococci. The antibacterial activity of bambermycin (Flavomycin) was strongly inhibited by the addition of blood, except with the species Enterococcus faecium, Enterococcus mundtii, Enterococcus hirae, Enterococcus casseliflavus, and Enterococcus gallinarum, which were not susceptible to this antibiotic on blood-free medium. With all other antimicrobials except avoparcin and tylosin, the presence of blood resulted in MIC increases of 1 to 3 log2 differences. Incubation in aerobic or anaerobic atmospheres enriched with CO2 lowered the susceptibility of enterococci to tylosin and increased their susceptibility to avilamycin, narasin, and avoparcin. This effect was most pronounced in tests on blood-free media. Results of susceptibility tests incubated under anaerobiosis and in a CO2-enriched atmosphere did not differ. For all enterococcal species, the preferred conditions for testing the susceptibility are Mueller-Hinton II medium supplemented with blood and incubation in a CO2-enriched atmosphere. However, when only E. faecium and Enterococcus faecalis are being tested, Mueller-Hinton II medium without blood incubated aerobically gives satisfactory results. PMID:9650934

  18. A microscopy study of hyphal growth of Penicillium rubens on gypsum under dynamic humidity conditions.

    PubMed

    van Laarhoven, Karel A; Huinink, Hendrik P; Adan, Olaf C G

    2016-05-01

    To remediate indoor fungal growth, understanding the moisture relations of common indoor fungi is crucial. Indoor moisture conditions are commonly quantified by the relative humidity (RH). RH is a major determinant of the availability of water in porous indoor surfaces that fungi grow on. The influence of steady-state RH on growth is well understood. Typically, however, the indoor RH constantly changes so that fungi have to endure frequent periods of alternating low and high RH. Knowledge of how common indoor fungi survive and are affected by the low-RH periods is limited. In particular, the specific effects of a drop in RH on the growth of the mycelium remain unclear. In this work, video microscopy was used to monitor hyphal growth of Penicillium rubens on gypsum substrates under controlled dynamic humidity conditions. The effect of a single period of low RH (RH = 50-90%) interrupting favourable conditions (RH = 97%) was tested. It was found that hyphal tips ceased to extend when exposed to any tested decrease in RH. However, new hyphal growth always emerges, seemingly from the old mycelium, suggesting that this indoor fungus does not rely only on conidia to survive the humidity patterns considered. These findings are a fundamental step in unravelling the effect of RH on indoor fungal growth. PMID:26996401

  19. Evaluation of Cronobacter Growth and Phenotypic Variation Under Modified Culture Conditions.

    PubMed

    Segars, Katharine; Simpson, Steven; Kerdahi, Khalil; Sulaiman, Irshad M

    2016-02-01

    Cronobacter sakazakii is an opportunistic pathogen known to cause acute meningitis and necrotizing enterocolitis in neonates and immunocompromised individuals. It has been isolated from a wide range of food and environmental samples, and has been linked to outbreaks associated with powdered infant formula. This study was carried out to assess variations in growth conditions (temperature, pH, and sugar supplement) and to establish how these changes impact phenotypic characteristics for successful recovery and identification of Cronobacter, particularly for routine surveillance purposes. A total of six Cronobacter isolates were tested to evaluate the above growth conditions, including three ATCC Cronobacter reference and three environmental isolates obtained from regulatory sample screening. Although only slight changes in colony-forming units were observed across the pH range and the sugars tested, the morphology was significantly impacted by changes in these growth factors. Incubation between 30 and 50 °C resulted in growth after 24 h, and the growth was slower at ambient temperature and colony formation was most robust at 30 °C. Results of this study suggest that 30 °C may be suitable for recovery of some Cronobacter strains, and minor variations in growth conditions can alter colony morphology and appearance. Expression of unique biological characteristics based on phenotypic observations may be beneficial for differentiating various Cronobacter strains. PMID:26567034

  20. Oceanographic conditions govern shell growth of Arctica islandica (Bivalvia) in surface waters off Northeast Iceland

    NASA Astrophysics Data System (ADS)

    Marali, Soraya; Schöne, Bernd R.

    2015-04-01

    Shells of the long-lived bivalve Arctica islandica provide absolutely dated, highly resolved archives of environmental variability in the extratropical realm. Shell growth rates of contemporaneous A. islandica specimens are synchronized by one or several environmental factor(s), such as seawater temperature, food supply etc. Based on the growth synchrony, increment width records can be combined to composite chronologies. However, according to existing studies, A. islandica specimens from shallow waters do not show synchronous changes in shell growth and may thus not provide information about environmental conditions such as sea surface temperature. Here, we present the first statistically robust composite chronology of A. islandica from unpolluted surface waters (8-23 m) off Northeast Iceland. The complete record spans the time interval of 1835 to 2012. Times of enhanced shell growth coincide with periods of higher temperature and elevated food supply. Instrumental sea surface temperature (SST) during the growing season explains up to 43% of the variation in relative shell growth. However, the correlation strength varies over time. When the environmental conditions at the sampling site were stable over many consecutive years, i.e. one of the two major surface currents (the warm, nutrient-rich Irminger Current or the cold, nutrient-deficient East Icelandic Current) predominated the area over longer time intervals, the growth synchrony among coeval A. islandica weakened and the correlation between shell growth and SSTs was markedly reduced. Conversely, if the habitat was under the alternating influence of both ocean currents, shell growth was stronger correlated to each other and to SST. Thus, environmental variability is required to synchronize shell growth rates within an A. islandica population. This study further enlightens the relationship between bivalve shell growth and environmental variables.

  1. A NEW CONDITION FOR THE TRANSITION FROM RUNAWAY TO OLIGARCHIC GROWTH

    SciTech Connect

    Ormel, C. W.; Dullemond, C. P.; Spaans, M. E-mail: dullemon@mpia.de

    2010-05-01

    Accretion among macroscopic bodies of {approx}km size or larger is enhanced significantly due to gravitational focusing. Two regimes can be distinguished. Initially, the system experiences runaway growth, in which the gravitational focusing factors increase, and bodies at the high-mass tail of the distribution grow fastest. However, at some point, the runaway body dynamically heats its environment, gravitational focusing factors decrease, and runaway growth passes into oligarchic growth. Based on the results of recent simulations, we reconsider the runaway growth-oligarchy transition. In contrast to oligarchy, we find that runaway growth cannot be approximated with a two-component model (of small and large bodies) and that the criterion of Ida and Makino, which is frequently adopted as the start of oligarchy, is not a sufficient condition to signify the transition. Instead, we propose a new criterion based on timescale arguments. We then find a larger value for the runaway growth-oligarchy transition: from several hundreds of km in the inner disk regions up to {approx}10{sup 3} km for the outer disk. These findings are consistent with the view that runaway growth has been responsible for the size distribution of the present-day Kuiper Belt objects. Our finding, furthermore, outlines the proper initial conditions at the start of the oligarchy stage.

  2. Glycerol as a substrate for aerobic succinate production in minimal medium with Corynebacterium glutamicum

    PubMed Central

    Litsanov, Boris; Brocker, Melanie; Bott, Michael

    2013-01-01

    Corynebacterium glutamicum, an established microbial cell factory for the biotechnological production of amino acids, was recently genetically engineered for aerobic succinate production from glucose in minimal medium. In this work, the corresponding strains were transformed with plasmid pVWEx1-glpFKD coding for glycerol utilization genes from Escherichia coli. This plasmid had previously been shown to allow growth of C. glutamicum with glycerol as sole carbon source. The resulting strains were tested in minimal medium for aerobic succinate production from glycerol, which is a by-product in biodiesel synthesis. The best strain BL-1/pVWEx1-glpFKD formed 79 mM (9.3 g l−1) succinate from 375 mM glycerol, representing 42% of the maximal theoretical yield under aerobic conditions. A specific succinate production rate of 1.55 mmol g−1 (cdw) h−1 and a volumetric productivity of 3.59 mM h−1 were obtained, the latter value representing the highest one currently described in literature. The results demonstrate that metabolically engineered strains of C. glutamicum are well suited for aerobic succinate production from glycerol. PMID:22513227

  3. Benzoate-induced stress enhances xylitol yield in aerobic fed-batch culture of Candida mogii TISTR 5892.

    PubMed

    Wannawilai, Siwaporn; Sirisansaneeyakul, Sarote; Chisti, Yusuf

    2015-01-20

    Production of the natural sweetener xylitol from xylose via the yeast Candida mogii TISTR 5892 was compared with and without the growth inhibitor sodium benzoate in the culture medium. Sodium benzoate proved to be an uncompetitive inhibitor in relatively poorly oxygenated shake flask aerobic cultures. In a better controlled aerobic environment of a bioreactor, the role of sodium benzoate could equally well be described as competitive, uncompetitive or noncompetitive inhibitor of growth. In intermittent fed-batch fermentations under highly aerobic conditions, the presence of sodium benzoate at 0.15gL(-1) clearly enhanced the xylitol titer relative to the control culture without the sodium benzoate. The final xylitol concentration and the average xylitol yield on xylose were nearly 50gL(-1) and 0.57gg(-1), respectively, in the presence of sodium benzoate. Both these values were substantially higher than reported for the same fermentation under microaerobic conditions. Therefore, a fed-batch aerobic fermentation in the presence of sodium benzoate is promising for xylitol production using C. mogii. PMID:25499077

  4. Effect of aeration during cell growth on ketone reactions by immobilized yeast.

    PubMed

    Gervais, T R; Carta, G; Gainer, J L

    2000-01-01

    The effect of aeration during cell growth on the subsequent reduction of 2-hexanone and 2-octanone by yeast cells entrapped in calcium alginate beads was studied. The reactions were conducted using 2-propanol as a sacrificial substrate to regenerate the cofactor NAD(H), and a mixture of (S)- and (R)-alcohols was produced. The use of strictly aerobic conditions when growing the cells resulted in the highest initial reaction rates, as well as the production of only a single product (i.e., the enantiomeric excess of the (S)-alcohols was 1.0). However, initial reaction rates decreased proportionally with fermentation time regardless of whether the yeast were grown aerobically or under both aerobic and anaerobic conditions. The data also suggest that it is the aerobic (or anaerobic) condition, rather than the cell growth phase, which is responsible for the results seen. PMID:10753445

  5. Characteristics of aerobic granulation at mesophilic temperatures in wastewater treatment.

    PubMed

    Cui, Fenghao; Park, Seyong; Kim, Moonil

    2014-01-01

    Compact and structurally stable aerobic granules were developed in a sequencing batch reactor (SBR) at mesophilic temperatures (35°C). The morphological, biological and chemical characteristics of the aerobic granulation were investigated and a theoretical granulation mechanism was proposed according to the results of the investigation. The mature aerobic granules had compact structure, small size (mean diameter of 0.24 mm), excellent settleability and diverse microbial structures, and were effective for the removal of organics and nitrification. The growth kinetics demonstrated that the biomass growth depended on coexistence and interactions between heterotrophs and autotrophs in the granules. The functions of heterotrophs and autotrophs created a compact and secure layer on the outside of the granules, protecting the inside sludge containing environmentally sensitive and slow growing microorganisms. The mechanism and the reactor performance may promise feasibility and efficiency for treating industry effluents at mesophilic temperatures using aerobic granulation. PMID:24211486

  6. Hbr1 Activates and Represses Hyphal Growth in Candida albicans and Regulates Fungal Morphogenesis under Embedded Conditions

    PubMed Central

    Pendrak, Michael L.; Roberts, David D.

    2015-01-01

    Transitions between yeast and hyphae are essential for Candida albicans pathogenesis. The genetic programs that regulate its hyphal development can be distinguished by embedded versus aerobic surface agar invasion. Hbr1, a regulator of white-opaque switching, is also a positive and negative regulator of hyphal invasion. During embedded growth at 24°C, an HBR1/hbr1 strain formed constitutively filamentous colonies throughout the matrix, resembling EFG1 null colonies, and a subset of long unbranched hyphal aggregates enclosed in a spindle-shaped capsule. Inhibition of adenylate cyclase with farnesol perturbed the filamentation of HBR1/hbr1 cells producing cytokinesis-defective hyphae whereas farnesol treated EFG1 null cells produced abundant opaque-like cells. Point mutations in the Hbr1 ATP-binding domain caused distinct filamentation phenotypes including uniform radial hyphae, hyphal sprouts, and massive yeast cell production. Conversely, aerobic surface colonies of the HBR1 heterozygote on Spider and GlcNAc media lacked filamentation that could be rescued by growth under low (5%) O2. Consistent with these morphogenesis defects, the HBR1 heterozygote exhibited attenuated virulence in a mouse candidemia model. These data define Hbr1 as an ATP-dependent positive and negative regulator of hyphal development that is sensitive to hypoxia. PMID:26039220

  7. Aerobic Exercise Program Reduces Anger Expression Among Overweight Children

    PubMed Central

    Tkacz, Joseph; Young-Hyman, Deborah; Boyle, Colleen A.; Davis, Catherine L.

    2009-01-01

    This study tested the effect of a structured aerobic exercise program on anger expression in healthy overweight children. Overweight, sedentary children were randomly assigned to an aerobic exercise program or a no-exercise control condition. All children completed the Pediatric Anger Expression Scale at baseline and posttest. Anger Out and Anger Expression scores were lower for the exercise condition at posttest. Fitness improvements contributed significantly to final models, and points earned for adherence correlated negatively with posttest Anger Out. An aerobic exercise program might be an effective strategy to reduce anger expression, including reduction of aggressive behavior, in overweight children. PMID:19168916

  8. Growth and physiological condition of black ducks reared on acidified wetlands

    USGS Publications Warehouse

    Rattner, B.A.; Haramis, G.M.; Chu, D.S.; Bunck, C.M.; Scanes, C.G.

    1987-01-01

    Acid deposition has been identified as one of several possible factors contributing to the decline of some waterfowl populations in North America. In an effort to examine the effects of acidification on black duck (Anas rubripes) recruitment, growth and physiological condition were monitored in ducklings foraging for a 10-day trial (days 10-20 of life) on acidified (pH 5.0) and : circumneutral (pH 6.8) fish-free emergent wetlands. Acidification of these wetlands suppressed phytoplankton and algal growth, and reduced invertebrate biomass. Ducklings maintained on acidified wetlands grew poorly compared with ducklings reared on circumneutral wetlands, as evidenced by lower final body weight and culmen and tarsus length. Plasma growth hormone concentration was elevated and triiodothyronine levels were lower in stunted ducklings, in part substantiating impairment of growth-regulating processes. Ducklings exhibiting poor growth tended to have lower hematocrit, lower plasma protein, glucose, and cholesterol concentrations, and higher uric acid levels, presumably reflecting alterations in metabolism and development due to inanition. These findings suggest that acid deposition may lower food production in wetlands and ultimately impair duckling growth, condition, and survival.

  9. Pseudomonas aeruginosa facilitates Campylobacter jejuni growth in biofilms under oxic flow conditions.

    PubMed

    Culotti, Alessandro; Packman, Aaron I

    2015-12-01

    We investigated the growth of Campylobacter jejuni in biofilms with Pseudomonas aeruginosa under oxic flow conditions. We observed the growth of C. jejuni in mono-culture, deposited on pre-established P. aeruginosa biofilms, and co-inoculated with P. aeruginosa. In mono-culture, C. jejuni was unable to form biofilms. However, deposited C. jejuni continuously grew on pre-established P. aeruginosa biofilms for a period of 3 days. The growth of scattered C. jejuni clusters was strictly limited to the P. aeruginosa biofilm surface, and no intergrowth was observed. Co-culturing of C. jejuni and P. aeruginosa also enabled the growth of both organisms in biofilms, with C. jejuni clusters developing on the surface of the P. aeruginosa biofilm. Dissolved oxygen (DO) measurements in the medium showed that P. aeruginosa biofilms depleted the effluent DO from 9.0 to 0.5 mg L(-1) 24 hours after inoculation. The localized microaerophilic environment generated by P. aeruginosa promoted the persistence and growth of C. jejuni. Our findings show that P. aeruginosa not only prolongs the survival of C. jejuni under oxic conditions, but also enables the growth of C. jejuni on the surface of P. aeruginosa biofilms. PMID:26610432

  10. Mitochondrial NAD Dependent Aldehyde Dehydrogenase either from Yeast or Human Replaces Yeast Cytoplasmic NADP Dependent Aldehyde Dehydrogenase for the Aerobic Growth of Yeast on Ethanol

    PubMed Central

    Mukhopadhyay, Abhijit; Wei, Baoxian; Weiner, Henry

    2013-01-01

    Background In a previous study, we deleted three aldehyde dehydrogenase (ALDH) genes, involved in ethanol metabolism, from yeast S. cerevisiae and found that the triple deleted yeast strain did not grow on ethanol as sole carbon source. The ALDHs were NADP dependent cytosolic ALDH1, NAD dependent mitochondrial ALDH2 and NAD/NADP dependent mitochondrial ALDH5. Double deleted strain ΔALDH2+ΔALDH5 or ΔALDH1+ΔALDH5 could grow on ethanol. However, the double deleted strain ΔALDH1+ΔALDH2 did not grow in ethanol. Methods Triple deleted yeast strain was used. Mitochondrial NAD dependent ALDH from yeast or human was placed in yeast cytosol. Results In the present study we found that a mutant form of cytoplasmic ALDH1 with very low activity barely supported the growth of the triple deleted strain (ΔALDH1+ΔALDH2+ΔALDH5) on ethanol. Finding the importance of NADP dependent ALDH1 on the growth of the strain on ethanol we examined if NAD dependent mitochondrial ALDH2 either from yeast or human would be able to support the growth of the triple deleted strain on ethanol if the mitochondrial form was placed in cytosol. We found that the NAD dependent mitochondrial ALDH2 from yeast or human was active in cytosol and supported the growth of the triple deleted strain on ethanol. Conclusion This study showed that coenzyme preference of ALDH is not critical in cytosol of yeast for the growth on ethanol. PMID:23454351

  11. Noninvasive Quantitative Measurement of Bacterial Growth in Porous Media under Unsaturated-Flow Conditions

    PubMed Central

    Yarwood, R. R.; Rockhold, M. L.; Niemet, M. R.; Selker, J. S.; Bottomley, P. J.

    2002-01-01

    Glucose-dependent growth of the luxCDABE reporter bacterium Pseudomonas fluorescens HK44 was monitored noninvasively in quartz sand under unsaturated-flow conditions within a 45- by 56- by 1-cm two-dimensional light transmission chamber. The spatial and temporal development of growth were mapped daily over 7 days by quantifying salicylate-induced bioluminescence. A nonlinear model relating the rate of increase in light emission after salicylate exposure to microbial density successfully predicted growth over 4 orders of magnitude (r2 = 0.95). Total model-predicted growth agreed with growth calculated from the mass balance of the system by using previously established growth parameters of HK44 (predicted, 1.2 × 1012 cells; calculated, 1.7 × 1012 cells). Colonization expanded in all directions from the inoculation region, including upward migration against the liquid flow. Both the daily rate of expansion of the colonized zone and the population density of the first day's growth in each newly colonized region remained relatively constant throughout the experiment. Nonetheless, substantial growth continued to occur on subsequent days in the older regions of the colonized zone. The proportion of daily potential growth that remained within the chamber declined progressively between days 2 and 7 (from 97 to 13%). A densely populated, anoxic region developed in the interior of the colonized zone even though the sand was unsaturated and fresh growth medium continued to flow through the colonized zone. These data illustrate the potential of a light transmission chamber, bioluminescent bacteria, and sensitive digital camera technology to noninvasively study real-time hydrology-microbiology interactions associated with unsaturated flow in porous media. PMID:12089048

  12. Noninvasive Quantitative Measurement of Bacterial Growth in Porous Media Under Unsaturated-Flow Conditions

    SciTech Connect

    Yarwood, Rocky; Rockhold, Mark L. ); Niemet, Mike; Selker, John S.; Bottomley, Peter J.

    2002-07-01

    Glucose-dependent growth of the luxCDABE reporter bacterium Pseudomonas fluorescens HK44 was monitored noninvasively in quartz sand under unsaturated-flow conditions within a 45- by 56- by 1-cm two-dimensional light transmission chamber. The spatial and temporal development of growth were mapped daily over 7 days by quantifying salicylate-induced bioluminescence. A nonlinear model relating the rate of increase in light emission after salicylate exposure to microbial density successfully predicted growth over 4 orders of magnitude (r{sup 2}=0.95). Total model-predicted growth agreed with growth calculated from the mass balance of the system by using previously determined growth parameters of HK44 (predicted, 1.2 x 10{sup 12} cells; calculated, 1.7 x 10{sup 12} cells). Colonization expanded in all directions from the inoculation region, including upward migration against the liquid flow. Both the daily rate of expansion of the colonized zone and the population density of the first day's growth in each newly colonized region remained relatively constant throughout the experiment. Nonetheless, substantial growth continued to occur on subsequent days in the older regions of the colonized zone. The proportion of daily potential growth that remained within the chamber declined progressively between days 2 and 7 (from 97 to 13%). A densely populated, anoxic region developed in the interior of the colonized zone even though the sand was unsaturated and fresh growth medium continued to flow through the colonized zone. These data illustrate the potential of a light transmission chamber, bioluminescent bacteria, and sensitive digital camera technology to noninvasively study real-time hydrology-microbiology interactions associated with unsaturated flow in porous media.

  13. Individual Differences in the Expression of Conditioned Fear Are Associated with Endogenous Fibroblast Growth Factor 2

    ERIC Educational Resources Information Center

    Graham, Bronwyn M.; Richardson, Rick

    2016-01-01

    These experiments examined the relationship between the neurotrophic factor fibroblast growth factor 2 (FGF2) and individual differences in the expression of conditioned fear. Experiments 1 and 2 demonstrated that rats naturally expressing low levels of contextual or cued fear have higher levels of hippocampal FGF2 relative to rats that express…

  14. ASSESSMENT OF FUNGAL GROWTH ON CEILING TILES UNDER ENVIRONMENTALLY CHARACTERIZED CONDITIONS

    EPA Science Inventory

    The paper discusses investigation of the impact of the building environment on the ability of building materials to support microbial growth, using static chambers with defined relative humidity, temperature, and light conditions. he ability of fungi to grow on materials is well ...

  15. Using time-dependent models to investigate body condition and growth rate of the giant gartersnake

    USGS Publications Warehouse

    Coates, P.S.; Wylie, G.D.; Halstead, B.J.; Casazza, M.L.

    2009-01-01

    Identifying links between phenotypic attributes and fitness is a primary goal of reproductive ecology. Differences in within-year patterns of body condition between sexes of gartersnakes in relation to reproduction and growth are not fully understood. We conducted an 11-year field study of body condition and growth rate of the giant gartersnake Thamnophis gigas across 13 study areas in the Central Valley of California, USA. We developed a priori mixed effects models of body condition index (BCI), which included covariates of time, sex and snout-vent length and reported the best-approximating models using an information theoretic approach. Also, we developed models of growth rate index (GRI) using covariates of sex and periods based on reproductive behavior. The largest difference in BCI between sexes, as predicted by a non-linear (cubic) time model, occurred during the mating period when female body condition (0.014??0.001 se) was substantially greater than males (-0.027??0.002 se). Males likely allocated energy to search for mates, while females likely stored energy for embryonic development. We also provided evidence that males use more body energy reserves than females during hibernation, perhaps because of different body temperatures between sexes. We found GRI of male snakes was substantially lower during the mating period than during a non-mating period, which indicated that a trade-off existed between searching for mates and growth. These findings contribute to our understanding of snake ecology in a Mediterranean climate. ?? 2009 The Zoological Society of London.

  16. The Agony of Choice: How Plants Balance Growth and Survival under Water-Limiting Conditions1

    PubMed Central

    Claeys, Hannes; Inzé, Dirk

    2013-01-01

    When confronted with water limitation, plants actively reprogram their metabolism and growth. Recently, it has become clear that growing tissues show specific and highly dynamic responses to drought, which differ from the well-studied responses in mature tissues. Here, we provide an overview of recent advances in understanding shoot growth regulation in water-limiting conditions. Of special interest is the balance between maintained growth and competitiveness on the one hand and ensured survival on the other hand. A number of master regulators controlling this balance have been identified, such as DELLAs and APETALA2/ETHYLENE RESPONSE FACTOR-type transcription factors. The possibilities of engineering or breeding crops that maintain growth in periods of mild drought, while still being able to activate protective tolerance mechanisms, are discussed. PMID:23766368

  17. Effectiveness of rhizobacteria containing ACC deaminase for growth promotion of peas (Pisum sativum) under drought conditions.

    PubMed

    Zahir, Z A; Munir, A; Asghar, H N; Shaharoona, B; Arshad, M

    2008-05-01

    A series of experiments were conducted to assess the effectiveness of rhizobacteria containing 1-aminocyclopropane- 1-carboxylate (ACC) deaminase for growth promotion of peas under drought conditions. Ten rhizobacteria isolated from the rhizosphere of different crops (peas, wheat, and maize) were screened for their growth promoting ability in peas under axenic condition. Three rhizobacterial isolates, Pseudomonas fluorescens biotype G (ACC-5), P. fluorescens (ACC-14), and P. putida biotype A (Q-7), were selected for pot trial on the basis of their source, ACC deaminase activity, root colonization, and growth promoting activity under axenic conditions. Inoculated and uninoculated (control) seeds of pea cultivar 2000 were sown in pots (4 seeds/pot) at different soil moisture levels (25, 50, 75, and 100% of field capacity). Results revealed that decreasing the soil moisture levels from 100 to 25% of field capacity significantly decreased the growth of peas. However, inoculation of peas with rhizobacteria containing ACC deaminase significantly decreased the "drought stress imposed effects" on growth of peas, although with variable efficacy at different moisture levels. At the lowest soil moisture level (25% field capacity), rhizobacterial isolate Pseudomonas fluorescens biotype G (ACC-5) was found to be more promising compared with the other isolates, as it caused maximum increases in fresh weight, dry weight, root length, shoot length, number of leaves per plant, and water use efficiency on fresh and dry weight basis (45, 150, 92, 45, 140, 46, and 147%, respectively) compared with respective uninoculated controls. It is highly likely that rhizobacteria containing ACC deaminase might have decreased the drought-stress induced ethylene in inoculated plants, which resulted in better growth of plants even at low moisture levels. Therefore, inoculation with rhizobacteria containing ACC deaminase could be helpful in eliminating the inhibitory effects of drought stress on the

  18. Keratinocyte growth factor and hepatocyte growth factor/scatter factor are heparin-binding growth factors for alveolar type II cells in fibroblast-conditioned medium.

    PubMed Central

    Panos, R J; Rubin, J S; Csaky, K G; Aaronson, S A; Mason, R J

    1993-01-01

    Epithelial-mesenchymal interactions mediate aspects of normal lung growth and development and are important in the restoration of normal alveolar architecture after lung injury. To determine if fibroblasts are a source of soluble growth factors for alveolar type II cells, we investigated the effect of fibroblast-conditioned medium (CM) on alveolar type II cell DNA synthesis. Serum-free CM from confluent adult human lung fibroblasts was concentrated fivefold by lyophilization. Type II cells were isolated from adult rats by elastase dissociation and incubated with [3H]thymidine and varying dilutions of concentrated CM and serum from day 1 to 3 of culture. Stimulation of type II cell DNA synthesis by fibroblast-CM was maximal after 48 h of conditioning and required the presence of serum. The activity of the CM was eliminated by boiling and by treatment with trypsin, pepsin, or dithiothreitol and was additive with saturating concentrations of acidic fibroblast growth factor, epidermal growth factor, and insulin. The growth factor activity bound to heparin-Sepharose and was eluted with 0.6 and 1.0 M NaCl. Neutralizing antibody studies demonstrated that the primary mitogens isolated in the 0.6 and 1.0 M NaCl fractions were keratinocyte growth factor (KGF, fibroblast growth factor 7) and hepatocyte growth factor/scatter factor (HGF/SF), respectively. HGF/SF was demonstrated in the crude CM and KGF was detected in the 0.6 M NaCl eluent by immunoblotting. Northern blot analysis confirmed that the lung fibroblasts expressed both KGF and HGF/SF transcripts. Human recombinant KGF and HGF/SF induced a concentration- and serum-dependent increase in rat alveolar type II cell DNA synthesis. We conclude that adult human lung fibroblasts produce at least two soluble heparin-binding growth factors, KGF and HGF/SF, which promote DNA synthesis and proliferation of rat alveolar type II cells in primary culture. KGF and HGF/SF may be important stimuli for alveolar type II cell

  19. Growth of silicone-immobilized bacteria on polycarbonate membrane filters, a technique to study microcolony formation under anaerobic conditions.

    PubMed Central

    Højberg, O; Binnerup, S J; Sørensen, J

    1997-01-01

    A technique was developed to study microcolony formation by silicone-immobilized bacteria on polycarbonate membrane filters under anaerobic conditions. A sudden shift to anaerobiosis was obtained by submerging the filters in medium which was depleted for oxygen by a pure culture of bacteria. The technique was used to demonstrate that preinduction of nitrate reductase under low-oxygen conditions was necessary for nonfermenting, nitrate-respiring bacteria, e.g., Pseudomonas spp., to cope with a sudden lack of oxygen. In contrast, nitrate-respiring, fermenting bacteria, e.g., Bacillus and Escherichia spp., formed microcolonies under anaerobic conditions with or without the presence of nitrate and irrespective of aerobic or anaerobic preculture conditions. PMID:9212439

  20. Kinetic modeling of growth and lipid body induction in Chlorella pyrenoidosa under heterotrophic conditions.

    PubMed

    Sachdeva, Neha; Kumar, G Dinesh; Gupta, Ravi Prakash; Mathur, Anshu Shankar; Manikandan, B; Basu, Biswajit; Tuli, Deepak Kumar

    2016-10-01

    The aim of the present work was to develop a mathematical model to describe the biomass and (total) lipid productivity of Chlorella pyrenoidosa NCIM 2738 under heterotrophic conditions. Biomass growth rate was predicted by Droop's cell quota model, while changes observed in cell quota (utilization) under carbon excess conditions were used for the modeling and predicting the lipid accumulation rate. The model was simulated under non-limiting (excess) carbon and limiting nitrate concentration and validated with experimental data for the culture grown in batch (flask) mode under different nitrate concentrations. The present model incorporated two modes (growth and stressed) for the prediction of endogenous lipid synthesis/induction and aimed to predict the effect and response of the microalgae under nutrient starvation (stressed) conditions. MATLAB and Genetic Algorithm were employed for the prediction and validation of the model parameters. PMID:27450124

  1. Development of a Fatigue Crack Growth Coupon for Highly Plastic Stress Conditions

    NASA Technical Reports Server (NTRS)

    Allen, Phillip A.; Aggarwal, Pravin K.; Swanson, Gregory R.

    2003-01-01

    The analytical approach used to develop a novel fatigue crack growth coupon for highly plastic stress field condition is presented in this paper. The flight hardware investigated is a large separation bolt that has a deep notch, which produces a large plastic zone at the notch root when highly loaded. Four test specimen configurations are analyzed in an attempt to match the elastic-plastic stress field and crack constraint conditions present in the separation bolt. Elastic-plastic finite element analysis is used to compare the stress fields and critical fracture parameters. Of the four test specimens analyzed, the modified double-edge notch tension - 3 (MDENT-3) most closely approximates the stress field, J values, and crack constraint conditions found in the flight hardware. The MDENT-3 is also most insensitive to load misalignment and/or load redistribution during crack growth.

  2. Clinically Relevant Growth Conditions Alter Acinetobacter baumannii Antibiotic Susceptibility and Promote Identification of Novel Antibacterial Agents

    PubMed Central

    Colquhoun, Jennifer M.; Wozniak, Rachel A. F.; Dunman, Paul M.

    2015-01-01

    Biological processes that govern bacterial proliferation and survival in the host-environment(s) are likely to be vastly different from those that are required for viability in nutrient-rich laboratory media. Consequently, growth-based antimicrobial screens performed in conditions modeling aspects of bacterial disease states have the potential to identify new classes of antimicrobials that would be missed by screens performed in conventional laboratory media. Accordingly, we performed screens of the Selleck library of 853 FDA approved drugs for agents that exhibit antimicrobial activity toward the Gram-negative bacterial pathogen Acinetobacter baumannii during growth in human serum, lung surfactant, and/or the organism in the biofilm state and compared those results to that of conventional laboratory medium. Results revealed that a total of 90 compounds representing 73 antibiotics and 17 agents that were developed for alternative therapeutic indications displayed antimicrobial properties toward the test strain in at least one screening condition. Of the active library antibiotics only four agents, rifampin, rifaximin, ciprofloxacin and tetracycline, exhibited antimicrobial activity toward the organism during all screening conditions, whereas the remainder were inactive in ≥ 1 condition; 56 antibiotics were inactive during serum growth, 25 and 38 were inactive toward lung surfactant grown and biofilm-associated cells, respectively, suggesting that subsets of antibiotics may outperform others in differing infection settings. Moreover, 9 antibiotics that are predominantly used for the treatment Gram-positive pathogens and 10 non-antibiotics lacked detectable antimicrobial activity toward A. baumannii grown in conventional medium but were active during ≥ 1 alternative growth condition(s). Such agents may represent promising anti-Acinetobacter agents that would have likely been overlooked by antimicrobial whole cell screening assays performed in traditional

  3. Conditional expression of constitutively active estrogen receptor {alpha} in chondrocytes impairs longitudinal bone growth in mice

    SciTech Connect

    Ikeda, Kazuhiro; Tsukui, Tohru; Imazawa, Yukiko; Horie-Inoue, Kuniko; Inoue, Satoshi

    2012-09-07

    Highlights: Black-Right-Pointing-Pointer Conditional transgenic mice expressing constitutively active estrogen receptor {alpha} (caER{alpha}) in chondrocytes were developed. Black-Right-Pointing-Pointer Expression of caER{alpha} in chondrocytes impaired longitudinal bone growth in mice. Black-Right-Pointing-Pointer caER{alpha} affects chondrocyte proliferation and differentiation. Black-Right-Pointing-Pointer This mouse model is useful for understanding the physiological role of ER{alpha}in vivo. -- Abstract: Estrogen plays important roles in the regulation of chondrocyte proliferation and differentiation, which are essential steps for longitudinal bone growth; however, the mechanisms of estrogen action on chondrocytes have not been fully elucidated. In the present study, we generated conditional transgenic mice, designated as caER{alpha}{sup ColII}, expressing constitutively active mutant estrogen receptor (ER) {alpha} in chondrocytes, using the chondrocyte-specific type II collagen promoter-driven Cre transgenic mice. caER{alpha}{sup ColII} mice showed retardation in longitudinal growth, with short bone lengths. BrdU labeling showed reduced proliferation of hypertrophic chondrocytes in the proliferating layer of the growth plate of tibia in caER{alpha}{sup ColII} mice. In situ hybridization analysis of type X collagen revealed that the maturation of hypertrophic chondrocytes was impaired in caER{alpha}{sup ColII} mice. These results suggest that ER{alpha} is a critical regulator of chondrocyte proliferation and maturation during skeletal development, mediating longitudinal bone growth in vivo.

  4. Auxin polar transport in arabidopsis under simulated microgravity conditions - relevance to growth and development

    NASA Astrophysics Data System (ADS)

    Miyamoto, K.; Oka, M.; Yamamoto, R.; Masuda, Y.; Hoson, T.; Kamisaka, S.; Ueda, J.

    1999-01-01

    Activity of auxin polar transport in inflorescence axes of Arabidopsis thaliana grown under simulated microgravity conditions was studied in relation to the growth and development. Seeds were germinated and allowed to grow on an agar medium in test tubes on a horizontal clinostat. Horizontal clinostat rotation substantially reduced the growth of inflorescence axes and the productivity of seeds of Arabidopsis thaliana (ecotypes Landsberg erecta and Columbia), although it little affected seed germination, development of rosette leaves and flowering. The activity of auxin polar transport in inflorescence axes decreased when Arabidopsis plants were grown on a horizontal clinostat from germination stage, being ca. 60% of 1 g control. On the other hand, the auxin polar transport in inflorescence axes of Arabidopsis grown in 1 g conditions was not affected when the segments were exposed to various gravistimuli, including 3-dimensional clinorotation, during transport experiments. Pin-formed mutant of Arabidopsis, having a unique structure of the inflorescence axis with no flower and extremely low levels of the activity of auxin polar transport in inflorescence axes and endogenous auxin, did not continue its vegetative growth under clinostat rotation. These facts suggest that the development of the system of auxin polar transport in Arabidopsis is affected by microgravity, resulting in the inhibition of growth and development, especially during reproductive growth.

  5. High-throughput dental biofilm growth analysis for multiparametric microenvironmental biochemical conditions using microfluidics.

    PubMed

    Lam, Raymond H W; Cui, Xin; Guo, Weijin; Thorsen, Todd

    2016-04-26

    Dental biofilm formation is not only a precursor to tooth decay, but also induces more serious systematic health problems such as cardiovascular disease and diabetes. Understanding the conditions promoting colonization and subsequent biofilm development involving complex bacteria coaggregation is particularly important. In this paper, we report a high-throughput microfluidic 'artificial teeth' device offering controls of multiple microenvironmental factors (e.g. nutrients, growth factors, dissolved gases, and seeded cell populations) for quantitative characteristics of long-term dental bacteria growth and biofilm development. This 'artificial teeth' device contains multiple (up to 128) incubation chambers to perform parallel cultivation and analyses (e.g. biofilm thickness, viable-dead cell ratio, and spatial distribution of multiple bacterial species) of bacteria samples under a matrix of different combinations of microenvironmental factors, further revealing possible developmental mechanisms of dental biofilms. Specifically, we applied the 'artificial teeth' to investigate the growth of two key dental bacteria, Streptococci species and Fusobacterium nucleatum, in the biofilm under different dissolved gas conditions and sucrose concentrations. Together, this high-throughput microfluidic platform can provide extended applications for general biofilm research, including screening of the biofilm properties developing under combinations of specified growth parameters such as seeding bacteria populations, growth medium compositions, medium flow rates and dissolved gas levels. PMID:27045372

  6. Measurement of a tree growth condition by the hetero-core optical fiber sensor

    NASA Astrophysics Data System (ADS)

    Uchida, Hoshito; Akita, Shohei; Nishiyama, Michiko; Kumekawa, Norikazu; Watanabe, Kazuhiro

    2011-04-01

    Condition and growth of trees are considered to be important in monitoring global circulation with heat and water, additionally growth of trees are affected by CO2 and air pollutants. On the other hand, since growth of plants is affected by surrounding climates, it is expected that real-time monitoring of crop plants growing makes possible quantitative agricultural management. This study proposed methods in measuring tree growth using hetero-core optical fiber sensors which are suitable for long-term, remote and real-time monitoring in wide area due to their features such as independence from temperature fluctuation and weather condition in addition to advantages of an optical fiber. Two types of sensors were used for that purpose. One of them was a dendrometer which measured radial changes of a tree stem and the other was elastic sensor which was to measure growth of smaller tree such as crop plant. In our experiment, it was demonstrated that the dendrometer was capable of measuring the differences of tree growing trend in period of different seasons such as growing rates 2.08 mm between spring and summer and 0.21 mm between autumn and winter, respectively. Additionally, this study had proposed the method of measuring crop plant growing by the elastic sensor because of its compact and light design and monotonious changes in optical loss to the amount of expansion and contraction.

  7. Growth of Continuous Monolayer Graphene with Millimeter-sized Domains Using Industrially Safe Conditions.

    PubMed

    Wu, Xingyi; Zhong, Guofang; D'Arsié, Lorenzo; Sugime, Hisashi; Esconjauregui, Santiago; Robertson, Alex W; Robertson, John

    2016-01-01

    We demonstrate the growth of continuous monolayer graphene films with millimeter-sized domains on Cu foils under intrinsically safe, atmospheric pressure growth conditions, suitable for application in roll-to-roll reactors. Previous attempts to grow large domains in graphene have been limited to isolated graphene single crystals rather than as part of an industrially useable continuous film. With both appropriate pre-treatment of the Cu and optimization of the CH4 supply, we show that it is possible to grow continuous films of monolayer graphene with millimeter scale domains within 80 min by chemical vapour deposition. The films are grown under industrially safe conditions, i.e., the flammable gases (H2 and CH4) are diluted to well below their lower explosive limit. The high quality, spatial uniformity, and low density of domain boundaries are demonstrated by charge carrier mobility measurements, scanning electron microscope, electron diffraction study, and Raman mapping. The hole mobility reaches as high as ~5,7002 m(2) V(-1) s(-1) in ambient conditions. The growth process of such high-quality graphene with a low H2 concentration and short growth times widens the possibility of industrial mass production. PMID:26883292

  8. Unfolded protein response is required for Aspergillus oryzae growth under conditions inducing secretory hydrolytic enzyme production.

    PubMed

    Tanaka, Mizuki; Shintani, Takahiro; Gomi, Katsuya

    2015-12-01

    Unfolded protein response (UPR) is an intracellular signaling pathway for adaptation to endoplasmic reticulum (ER) stress. In yeast UPR, Ire1 cleaves the unconventional intron of HAC1 mRNA, and the functional Hac1 protein translated from the spliced HAC1 mRNA induces the expression of ER chaperone genes and ER-associated degradation genes for the refolding or degradation of unfolded proteins. In this study, we constructed an ireA (IRE1 ortholog) conditionally expressing strain of Aspergillus oryzae, a filamentous fungus producing a large amount of amylolytic enzymes, and examined the contribution of UPR to ER stress adaptation under physiological conditions. Repression of ireA completely blocked A. oryzae growth under conditions inducing the production of hydrolytic enzymes, such as amylases and proteases. This growth defect was restored by the introduction of unconventional intronless hacA (hacA-i). Furthermore, UPR was observed to be induced by amylolytic gene expression, and the disruption of the transcriptional activator for amylolytic genes resulted in partial growth restoration of the ireA-repressing strain. In addition, a homokaryotic ireA disruption mutant was successfully generated using the strain harboring hacA-i as a parental host. These results indicated that UPR is required for A. oryzae growth to alleviate ER stress induced by excessive production of hydrolytic enzymes. PMID:26496881

  9. Growth of Continuous Monolayer Graphene with Millimeter-sized Domains Using Industrially Safe Conditions

    NASA Astrophysics Data System (ADS)

    Wu, Xingyi; Zhong, Guofang; D'Arsié, Lorenzo; Sugime, Hisashi; Esconjauregui, Santiago; Robertson, Alex W.; Robertson, John

    2016-02-01

    We demonstrate the growth of continuous monolayer graphene films with millimeter-sized domains on Cu foils under intrinsically safe, atmospheric pressure growth conditions, suitable for application in roll-to-roll reactors. Previous attempts to grow large domains in graphene have been limited to isolated graphene single crystals rather than as part of an industrially useable continuous film. With both appropriate pre-treatment of the Cu and optimization of the CH4 supply, we show that it is possible to grow continuous films of monolayer graphene with millimeter scale domains within 80 min by chemical vapour deposition. The films are grown under industrially safe conditions, i.e., the flammable gases (H2 and CH4) are diluted to well below their lower explosive limit. The high quality, spatial uniformity, and low density of domain boundaries are demonstrated by charge carrier mobility measurements, scanning electron microscope, electron diffraction study, and Raman mapping. The hole mobility reaches as high as ~5,700 cm2 V-1 s-1 in ambient conditions. The growth process of such high-quality graphene with a low H2 concentration and short growth times widens the possibility of industrial mass production.

  10. Growth of Continuous Monolayer Graphene with Millimeter-sized Domains Using Industrially Safe Conditions

    PubMed Central

    Wu, Xingyi; Zhong, Guofang; D'Arsié, Lorenzo; Sugime, Hisashi; Esconjauregui, Santiago; Robertson, Alex W.; Robertson, John

    2016-01-01

    We demonstrate the growth of continuous monolayer graphene films with millimeter-sized domains on Cu foils under intrinsically safe, atmospheric pressure growth conditions, suitable for application in roll-to-roll reactors. Previous attempts to grow large domains in graphene have been limited to isolated graphene single crystals rather than as part of an industrially useable continuous film. With both appropriate pre-treatment of the Cu and optimization of the CH4 supply, we show that it is possible to grow continuous films of monolayer graphene with millimeter scale domains within 80 min by chemical vapour deposition. The films are grown under industrially safe conditions, i.e., the flammable gases (H2 and CH4) are diluted to well below their lower explosive limit. The high quality, spatial uniformity, and low density of domain boundaries are demonstrated by charge carrier mobility measurements, scanning electron microscope, electron diffraction study, and Raman mapping. The hole mobility reaches as high as ~5,700 cm2 V−1 s−1 in ambient conditions. The growth process of such high-quality graphene with a low H2 concentration and short growth times widens the possibility of industrial mass production. PMID:26883292

  11. Growth and development in higher plants under simulated microgravity conditions on a 3-dimensional clinostat

    NASA Astrophysics Data System (ADS)

    Shimazu, T.; Yuda, T.; Miyamoto, K.; Yamashita, M.; Ueda, J.

    Growth and development of etiolated pea (Pisum sativum L. cv. Alaska) and maize (Zea mays L. cv. Golden Cross Bantam) seedlings grown under simulated microgravity conditions were intensively studied using a 3-dimensional clinostat as a simulator of weightlessness. Epicotyls of etiolated pea seedlings grown on the clinostat were the most oriented toward the direction far from cotyledons. Mesocotyls of etiolated maize seedlings grew at random and coleoptiles curved slightly during clinostat rotation. Clinostat rotation promoted the emergence of the 3rd internodes in etiolated pea seedlings, while it significantly inhibited the growth of the 1st internodes. In maize seedlings, the growth of coleoptiles was little affected by clinostat rotation, but that of mesocotyls was suppressed, and therefore, the emergence of the leaf out of coleoptile was promoted. Clinostat rotation reduced the osmotic concentration in the 1st internodes of pea seedlings, although it has little effect on the 2nd and the 3rd internodes. Clinostat rotation also reduced the osmotic concentrations in both coleoptiles and mesocotyls of maize seedlings. Cell-wall extensibilities of the 1st and the 3rd internodes of pea seedlings grown on the clinostat were significantly lower and higher as compared with those on 1 g conditions, respectively. Cell-wall extensibility of mesocotyls in seedlings grown on the clinostat also decreased. Changes in cell wall properties seem to be well correlated to the growth of each organ in pea and maize seedlings. These results suggest that the growth and development of plants is controlled under gravity on earth, and that the growth responses of higher plants to microgravity conditions are regulated by both cell-wall mechanical properties and osmotic properties of stem cells.

  12. Effect of Aerobic Priming on the Response of Echinochloa crus-pavonis to Anaerobic Stress (Protein Synthesis and Phosphorylation).

    PubMed Central

    Zhang, F.; Lin, J. J.; Fox, T. C.; Mujer, C. V.; Rumpho, M. E.; Kennedy, R. A.

    1994-01-01

    Echinochloa species differ in their ability to germinate and grow in the absence of oxygen. Seeds of Echinochloa crus-pavonis (H.B.K.) Schult do not germinate under anoxia but remain viable for extended periods (at least 30 d) when incubated in an anaerobic environment. E. crus-pavonis can be induced to germinate and grow in an anaerobic environment if the seeds are first subjected to a short (1-18 h) exposure to aerobic conditions (aerobic priming). Changes in polypeptide patterns (constitutive and de novo synthesized) and protein phosphorylation induced by aerobic priming were investigated. In the absence of aerobic priming protein degradation was not evident under anaerobic conditions, although synthesis of a 20-kD polypeptide was induced. During aerobic priming, however, synthesis of 37- and 55-kD polypeptides was induced and persisted upon return of the seeds to anoxia. Furthermore, phosphorylation of two 18-kD polypeptides was observed only in those seeds that were labeled with 32PO4 during the aerobic priming period. Subsequent chasing in an anaerobic environment resulted in a decrease in phosphorylation of these polypeptides. Likewise, phosphorylation of the 18-kD polypeptides was not observed if the seeds were labeled in an anaerobic atmosphere. These results suggest that the regulated induction of the 20-, 37-, and 55- kD polypeptides may be important for anaerobic germination and growth of E. crus-pavonis and that the specific phosphorylation of the 18-kD polypeptides may be a factor in regulating this induction. PMID:12232272

  13. Growth of Cronobacter spp. under dynamic temperature conditions occurring during cooling of reconstituted powdered infant formula.

    PubMed

    Kandhai, M C; Breeuwer, P; Gorris, L G M; Zwietering, M H; Reij, M W

    2009-12-01

    Reconstituted infant formulae are excellent growth media for Cronobacter spp. (formerly Enterobacter sakazakii) and other microorganisms that may be present in such products. Immediate consumption or rapid cooling and storage at a low temperature are therefore recommended as control measures to prevent microbial growth. Placing a container filled with reconstituted liquid formula in the refrigerator, however, does not mean that the temperature of the liquid is directly the same as the set-point of the refrigerator. This study describes the temperature profiles and methods to predict lag time and possible growth of Cronobacter spp. during the cooling process in three types of containers. The overall heat transfer coefficients (alpha) were determined and were shown to have a very large variability in both household refrigerators and an air-ventilated refrigerator equipped with a fan. A mathematical model was built to predict the growth of Cronobacter spp. under dynamic temperature conditions using three models for the lag time. The various estimations for the lag time had a remarkably strong impact on the predicted growth. The assumption of a constant k-value (k = lag time x specific growth rate = lambda x micro = 2.88) fitted the experimental data best. Predictions taking into account the large variability in heat transfer showed that proliferation of Cronobacter spp. during cooling may be prevented by limiting the volume to be cooled to portion size only, or by reconstituting at temperatures of 25 degrees C or lower. The model may also be used to predict growth in other situations where dynamic temperature conditions exist. PMID:20003730

  14. Nucleation and growth by diffusion under Ostwald-Freundlich boundary condition

    SciTech Connect

    Iwamatsu, Masao

    2014-02-14

    The critical radius of a nucleus grown by diffusion in a solution is studied thermodynamically as well as kinetically. The thermodynamic growth equation called Zeldovich equation of classical nucleation theory and the kinetic diffusional growth equation combined with the Ostwald-Freundlich boundary condition lead to the same critical radius. However, it should be pointed out that the diffusional equation may lead to a kinetic critical radius that is different from the thermodynamic critical radius, thus indicating the possibility of kinetically controlling the critical radius of a nucleus.

  15. Effect of growth conditions on the quality of lead bromide crystals

    NASA Technical Reports Server (NTRS)

    Singh, N. B.; Gottlieb, M.; Henningsen, T.; Hopkins, R. H.; Mazelsky, R.; Glicksman, M. E.; Coriell, S. R.; Duval, W. M. B.; Santoro, G. J.

    1992-01-01

    Single crystals of pure and doped lead bromide were grown by the Bridgman method in different convective conditions. The convection level was varied by changing the thermal and solutal Rayleigh number. The homogeneity in refractive index, and hence the optical quality, was estimated by examining the optical distortion, birefringence interferograms, and laser scattering through the crystal. The optical quality of the crystal varied significantly with the variation of convection level during the crystal growth. The critical concentration of the solute was estimated for several values of growth velocity by numerical analysis at the thermal gradient of 20 K/cm.

  16. Aerobic secondary utilization of a non-growth and inhibitory substrate 2,4,6-trichlorophenol by Sphingopyxis chilensis S37 and sphingopyxis-like strain S32.

    PubMed

    Aranda, Carlos; Godoy, Félix; Becerra, José; Barra, Ricardo; Martínez, Miguel

    2003-08-01

    This paper reports 2,4,6-trichlorophenol (246TCP) degradation by Sphingopyxis chilensis S37 and Sphingopyxis chilensis-like strain S32, which were unable to use 246TCP as the sole carbon and energy source. In R2A broth, the strains degraded 246TCP up to 0.5 mM. Results with mixtures of different 246TCP and glucose concentrations in mineral salt media demonstrated dependence on glucose to allow bacterial growth and degradation of 246TCP. Strain S32 degraded halophenol up to 0.2 mM when 5.33 mM glucose was simultaneously added, while strain S37 degraded the compound up to 0.1 mM when 1.33 mM glucose was added. These 246TCP concentrations were lethal for inocula in absence of glucose. Stoichiometric releases of chloride and analysis by HPLC, GC-ECD and GC-MS indicated 246TCP mineralisation by both strains. To our knowledge, this is the first report of bacteria able to mineralize a chlorophenol as a non-growth and inhibitory substrate. The concept of secondary utilization instead of cometabolism is proposed for this activity. PMID:12948056

  17. Conditions of growth of open corrosion pits in stainless steels -- Electrochemical experiments on model pits

    SciTech Connect

    Hakkarainen, T.J.

    1998-12-31

    The effects of the most important variables on continued growth and repassivation of open macroscopic corrosion pits in stainless steel sheets were investigated using two different artificial pit configurations. The pit growth was activated under anodic polarization either by injecting concentrated chloride solution into the pit or by initially filling the pit with chromic chloride crystals (CrCl{sub 3}-6H{sub 2}O). Experiments were made on sheet specimens of stainless steels of type UNS S31603 (316L) or UNS S312.54 in bulk solutions containing chloride and/or sulfate ions. Various aspects of the test arrangements and pitting of stainless steels are discussed, including the electrolyte composition within the pits, repassivation potentials and the IR-drops associated with pit growth. It is demonstrated that using the artificial pit configurations the effects of the main variables affecting the conditions for growth and repassivation of open corrosion pits can be investigated quantitatively, including electrode potentials, temperature, and composition of the bulk solution. It is concluded that for continued growth of corrosion pits with ``large`` openings to the bulk solution, a strongly oxidizing environment is required, and that sulfate ions in amounts comparable to or in excess of that of chloride ions may stabilize pit growth.

  18. Biphasic kinetics of growth and bacteriocin production with Lactobacillus amylovorus DCE 471 occur under stress conditions.

    PubMed

    Neysens, Patricia; Messens, Winy; Gevers, Dirk; Swings, Jean; De Vuyst, Luc

    2003-04-01

    Micro-organisms used during the production of fermented foods are subjected to several abiotic stresses. Microbial survival during these processes strongly depends on the ability of the cells to adapt and become more tolerant to the environmental conditions. Cultivation of Lactobacillus amylovorus DCE 471, a potential strain for use during type II sourdough fermentations, at low temperatures, unfavourable pH and high salt concentrations resulted in biphasic growth patterns. In addition, two separate bacteriocin peaks, as well as a dramatic change in cellular morphology, were observed. In general, an increase of the specific bacteriocin production occurred during the second growth phase. Finally, the observed sugar consumption profiles were affected by the applied fermentation temperature. Moreover, the highest bacteriocin activity occurred during maltose consumption at a low constant temperature of 28 degrees C and a constant pH of 5.4. Plate counts from both growth phases revealed the existence of two colony types. Irregular colonies were found to outnumber smoother colonies during the first growth phase, while the second growth phase was characterized by a greater number of smooth colonies. Electron microscopy was used to investigate the observed morphological switch at the single-cell level. Single, rod-shaped cells changed into elongated cells that grew in chains. Colony and cell morphology changes coincided with the biphasic growth pattern. PMID:12686649

  19. Fracture of Hydrided Zircaloy-4 Sheet under Through-Thickness Crack Growth Conditions

    SciTech Connect

    Raynaud, P.A.; Koss, D.A.; Motta, A.T.; Chan, K.S.

    2007-07-01

    The failure of thin-wall components such as fuel cladding may be caused by crack initiation on the component surface and subsequent crack growth through its thickness. This study has determined the fracture toughness of hydrided cold-worked stress relieved Zircaloy-4 sheet subject to through-thickness crack growth at 25 deg. C. The experimental approach utilizes a novel procedure in which a narrow linear strip of brittle hydride blister across the specimen width creates a well-defined pre-crack upon initial loading. The subsequent crack growth resistance is then characterized by four-point bending of the specimen and an elastic-plastic fracture mechanics analysis. At room temperature, the through-thickness fracture toughness (K{sub Q}) is sensitive to the orientation of the hydride platelets, and K{sub Q} {approx_equal} 25 MPavm for crack growth through a mixed in-plane/out-of-plane hydride field. In contrast, K{sub Q} is much higher ({approx_equal} 75 MPavm) when the hydride platelets are oriented predominantly in the plane of the sheet (and therefore normal to both the crack plane and the crack growth direction). The implication of these fracture toughness values to the fracture strain behavior of hydrided Zircaloy-4 under through-thickness crack growth conditions is illustrated. (authors)

  20. 3-D simulations to investigate initial condition effects on the growth of Rayleigh-Taylor mixing

    SciTech Connect

    Andrews, Malcolm J

    2008-01-01

    The effect of initial conditions on the growth rate of turbulent Rayleigh-Taylor (RT) mixing has been studied using carefully formulated numerical simulations. An integrated large-eddy simulation (ILES) that uses a finite-volume technique was employed to solve the three-dimensional incompressible Euler equations with numerical dissipation. The initial conditions were chosen to test the dependence of the RT growth parameters ({alpha}{sub b}, {alpha}{sub s}) on variations in (a) the spectral bandwidth, (b) the spectral shape, and (c) discrete banded spectra. Our findings support the notion that the overall growth of the RT mixing is strongly dependent on initial conditions. Variation in spectral shapes and bandwidths are found to have a complex effect of the late time development of the RT mixing layer, and raise the question of whether we can design RT transition and turbulence based on our choice of initial conditions. In addition, our results provide a useful database for the initialization and development of closures describing RT transition and turbulence.

  1. Seed storage conditions change the germination pattern of clonal growth plants in Mediterranean salt marshes.

    PubMed

    Espinar, José L; García, Luis V; Clemente, Luis

    2005-07-01

    The effect of salinity level and extended exposure to different salinity and flooding conditions on germination patterns of three salt-marsh clonal growth plants (Juncus subulatus, Scirpus litoralis, and S. maritimus) was studied. Seed exposure to extended flooding and saline conditions significantly affected the outcome of the germination process in a different, though predictable, way for each species, after favorable conditions for germination were restored. Tolerance of the germination process was related to the average salinity level measured during the growth/germination season at sites where established individuals of each species dominated the species cover. No relationship was found between salinity tolerance of the germination process and seed response to extended exposure to flooding and salinity conditions. The salinity response was significantly related to the conditions prevailing in the habitats of the respective species during the unfavorable (nongrowth/nongermination) season. Our results indicate that changes in salinity and hydrology while seeds are dormant affect the outcome of the seed-bank response, even when conditions at germination are identical. Because these environmental-history-dependent responses differentially affect seed germination, seedling density, and probably sexual recruitment in the studied and related species, these influences should be considered for wetland restoration and management. PMID:21646131

  2. Seed storage conditions change the germination pattern of clonal growth plants in Mediterranean salt marshes

    USGS Publications Warehouse

    Espinar, J.L.; Garcia, L.V.; Clemente, L.

    2005-01-01

    The effect of salinity level and extended exposure to different salinity and flooding conditions on germination patterns of three saltmarsh clonal growth plants (Juncus subulatus, Scirpus litoralis, and S. maritimus) was studied. Seed exposure to extended flooding and saline conditions significantly affected the outcome of the germination process in a different, though predictable, way for each species, after favorable conditions for germination were restored. Tolerance of the germination process was related to the average salinity level measured during the growth/germination season at sites where established individuals of each species dominated the species cover. No relationship was found between salinity tolerance of the germination process and seed response to extended exposure to flooding and salinity conditions. The salinity response was significantly related to the conditions prevailing in the habitats of the respective species during the unfavorable (nongrowth/nongermination) season. Our results indicate that changes in salinity and hydrology while seeds are dormant affect the outcome of the seed-bank response, even when conditions at germination are identical. Because these environmental-history-dependent responses differentially affect seed germination, seedling density, and probably sexual recruitment in the studied and related species, these influences should be considered for wetland restoration and management.

  3. Intracellular azo decolorization is coupled with aerobic respiration by a Klebsiella oxytoca strain.

    PubMed

    Yu, Lei; Zhang, Xiao-Yu; Xie, Tian; Hu, Jin-Mei; Wang, Shi; Li, Wen-Wei

    2015-03-01

    Reduction of azo dye methyl red coupled with aerobic respiration by growing cultures of Klebsiella oxytoca GS-4-08 was investigated. In liquid media containing dye and 0.6 % glucose in a mineral salts base, 100 mg l(-1) of the dye are completely removed in 3 h under shaking conditions. The dye cannot be aerobically decolorized by strain GS-4-08 without extra carbon sources, indicating a co-metabolism process. Higher initial dye concentration prolonged the lag phase of the cell growth, but final cell concentrations of each batches reached a same level with range from 6.3 to 7.6 mg l(-1) after the dye adaption period. This strain showed stronger dye tolerance and decolorization ability than many reported strains. Furthermore, a new intracellular oxygen-insensitive azoreductase was isolated from this strain, and the specific activity of enzyme was 0.846 and 0.633 U mg(-1) protein in the presence of NADH and NADPH, respectively. N,N dimethyl-p-phenylenediamine and anthranilic acid were stoichiometrically released from MR dye, indicating the breakage of azo bonds accounts for the intracellular decolorization. Combining the characteristics of azoreductase, the stoichiometry of EMP, and TCA cycle, the electron transfer chain theory of aerobic respiration, and the possible mechanism of aerobic respiration coupled with azo reduction by K. oxytoca GS-4-08 are proposed. This study is expected to provide a sound theoretical basis for the development of the K. oxytoca strain in aerobic process for azo dye containing wastewaters. PMID:25343980

  4. Growth and Survival of Some Probiotic Strains in Simulated Ice Cream Conditions

    NASA Astrophysics Data System (ADS)

    Homayouni, A.; Ehsani, M. R.; Azizi, A.; Razavi, S. H.; Yarmand, M. S.

    A Completely Randomized Design (CRD) experiment was applied in triplicates to evaluate the survival of four probiotic strains in simulated ice cream conditions. The growth and survival rate of these probiotic strains (Lactobacillus acidophilus, Lactobacillus casei, Bifidobacterium bifidum and Bifidobacterium longum) in varying amount of sucrose (10, 15, 20 and 25%), oxygen scavenging components (0.05% L-cysteine and 0.05% L-ascorbate) and temperatures (4 and -20°C) during different periods of time (1, 2 and 3 months) were evaluated in MRS-broth medium. Optical density at 580 nm was used to measure growth. Lactobacilli strains proved to be highly resistant in comparison with Biffidobacteria strains. The viable cell number of Lactobacillus casei in different sucrose concentrations, different oxidoreduction potentials and refrigeration temperature was 1x1010, 2x108 and 5x107 cfu mL-1, respectively. Growth and survival rate of Lactobacillus casei showed to be the highest.

  5. Environmental conditions impacting juvenile Chinook salmon growth off central California: An ecosystem model analysis

    NASA Astrophysics Data System (ADS)

    Fiechter, J.; Huff, D. D.; Martin, B. T.; Jackson, D. W.; Edwards, C. A.; Rose, K. A.; Curchitser, E. N.; Hedstrom, K. S.; Lindley, S. T.; Wells, B. K.

    2015-04-01

    A fully coupled ecosystem model is used to identify the effects of environmental conditions and upwelling variability on growth of juvenile Chinook salmon in central California coastal waters. The ecosystem model framework consists of an ocean circulation submodel, a biogeochemical submodel, and an individual-based submodel for salmon. Simulation results indicate that years favorable for juvenile salmon growth off central California are characterized by particularly intense early season upwelling (i.e., March through May), leading to enhanced krill concentrations during summer near the location of ocean entry (i.e., Gulf of the Farallones). Seasonally averaged growth rates in the model are generally consistent with observed values and suggest that juvenile salmon emigrating later in the season (i.e., late May and June) achieve higher weight gains during their first 90 days of ocean residency.

  6. Aerobic and two-stage anaerobic-aerobic sludge digestion with pure oxygen and air aeration.

    PubMed

    Zupancic, Gregor D; Ros, Milenko

    2008-01-01

    The degradability of excess activated sludge from a wastewater treatment plant was studied. The objective was establishing the degree of degradation using either air or pure oxygen at different temperatures. Sludge treated with pure oxygen was degraded at temperatures from 22 degrees C to 50 degrees C while samples treated with air were degraded between 32 degrees C and 65 degrees C. Using air, sludge is efficiently degraded at 37 degrees C and at 50-55 degrees C. With oxygen, sludge was most effectively degraded at 38 degrees C or at 25-30 degrees C. Two-stage anaerobic-aerobic processes were studied. The first anaerobic stage was always operated for 5 days HRT, and the second stage involved aeration with pure oxygen and an HRT between 5 and 10 days. Under these conditions, there is 53.5% VSS removal and 55.4% COD degradation at 15 days HRT - 5 days anaerobic, 10 days aerobic. Sludge digested with pure oxygen at 25 degrees C in a batch reactor converted 48% of sludge total Kjeldahl nitrogen to nitrate. Addition of an aerobic stage with pure oxygen aeration to the anaerobic digestion enhances ammonium nitrogen removal. In a two-stage anaerobic-aerobic sludge digestion process within 8 days HRT of the aerobic stage, the removal of ammonium nitrogen was 85%. PMID:17251012

  7. Fatigue Crack Growth Analysis Under Spectrum Loading in Various Environmental Conditions

    NASA Astrophysics Data System (ADS)

    Mikheevskiy, S.; Glinka, G.; Lee, E.

    2013-03-01

    model. The method can be also used to predict fatigue crack growth under constant amplitude and spectrum loading in various environmental conditions such as vacuum, air, and corrosive environment providing that appropriate limited constant amplitude fatigue crack growth data obtained in the same environment are available. The proposed methodology is equally suitable for fatigue analysis of smooth, notched, and cracked components.

  8. Aerobic landfill bioreactor

    DOEpatents

    Hudgins, Mark P; Bessette, Bernard J; March, John C; McComb, Scott T.

    2002-01-01

    The present invention includes a system of decomposing municipal solid waste (MSW) within a landfill by converting the landfill to aerobic degradation in the following manner: (1) injecting air via the landfill leachate collection system (2) injecting air via vertical air injection wells installed within the waste mass; (3) applying leachate to the waste mass using a pressurized drip irrigation system; (4) allowing landfill gases to vent; and (5) adjusting air injection and recirculated leachate to achieve a 40% to 60% moisture level and a temperature between 120.degree. F. and 140.degree. F. in steady state.

  9. Aerobic landfill bioreactor

    DOEpatents

    Hudgins, Mark P; Bessette, Bernard J; March, John; McComb, Scott T.

    2000-01-01

    The present invention includes a method of decomposing municipal solid waste (MSW) within a landfill by converting the landfill to aerobic degradation in the following manner: (1) injecting air via the landfill leachate collection system (2) injecting air via vertical air injection wells installed within the waste mass; (3) applying leachate to the waste mass using a pressurized drip irrigation system; (4) allowing landfill gases to vent; and (5) adjusting air injection and recirculated leachate to achieve a 40% to 60% moisture level and a temperature between 120.degree. F. and 140.degree. F. in steady state.

  10. Relations between coenzyme A and presumptive acyl carrier protein in different conditions of streptococcal growth.

    PubMed

    Das, D N; Toennies, G

    1969-06-01

    Exploration of the specific role of cystine in the postexponential growth of Streptococcus faecalis led to an inquiry into the fate of cellular coenzyme A (CoA) and acyl carrier protein (ACP), both of which depend for their biosynthesis on cystine and pantothenate as precursors. In S. faecalis cells labeled by growth in the presence of (14)C-pantothenate, the label could be separated on the basis of solubility at pH 2.1 into two fractions of sharply differing metabolic characteristics. The fractions were not purified, but the soluble (14)C behaved analytically like CoA, and the insoluble (14)C was considered to represent an ACP-like entity on the basis of circumstantial evidence. The fate of these two fractions under various conditions of growth was studied. When the medium contained an excess of the needed precursors, the cellular content of CoA and ACP appeared to remain constant during exponential growth, and in a molar ratio of about 4 CoA to 1 ACP. Cellular ACP, once formed, appeared to be stable under these conditions, but CoA was degraded and replaced at the rate of approximately 20% per division period. With restrictive levels of pantothenate in the medium, initially formed CoA disappeared during growth, as a result, apparently of being converted to ACP. However, when the resulting CoA-depleted cells were returned to a medium containing enough pantothenate, resumption of normal growth was preceded by a lag period, during which rapid conversion of ACP to CoA appeared to take place. PMID:4977991

  11. Influence of cell growth conditions and medium composition on EGFP photostability in live cells.

    PubMed

    Mamontova, Anastasia V; Bogdanov, Alexey M; Lukyanov, Konstantin A

    2015-05-01

    Photostability is a key characteristic of fluorescent proteins. It was recently demonstrated that green fluorescent protein (GFP) photobleaching in live cells can be suppressed by changes in medium composition. Here we show that Ham's F12 medium provides very high enhanced GFP (EGFP) photostability during fluorescence microscopy of live cells. This property of Ham's F12 medium is associated with decreased concentrations of riboflavin and pyridoxine, and increased concentrations of FeSO4, cyanocobalamine, lipoic acid, hypoxanthine, and thymidine compared with DMEM. We also found that the rate of EGFP photobleaching strongly depends on cell growth conditions such as cell density and the concentration of serum. We conclude that both imaging medium composition and the physiological state of the cells can strongly affect the photostability of fluorescent proteins. Thus, accurate comparison of the photostabilities of fluorescent proteins should be performed only in side-by-side analysis in identical cell growth conditions and media. PMID:25967905

  12. Monoraphidium sp. as an algal feedstock for biodiesel: Determining optimal growth conditions in wastewater

    NASA Astrophysics Data System (ADS)

    Davidson, Zachary William

    This thesis set out to investigate different conditions for growth of the freshwater algal species Monoraphidium sp. for use as a feedstock for biodiesel. The algae was inoculated into effluent gathered from a local water treatment plant and placed into 50gal mesocosms. Cells were grown at large scale in wastewater, harvested, and run through extractions to collect lipids (26%DW). The lipids were then turned into biodiesel. The algae also removed most of the pollutants in the wastewater, lowering nitrate and phosphate levels usually to less than 1mg/L. Erlenmeyer flask cultures (1L) were used to determine optimal growth conditions for temperature (10°C), light intensity (30microE/m2/sec with a 10 hour photoperiod), and initial inoculation density (1x104cells/mL). The addition of bicarbonate during the initial or exponential growth phase had no effect on growth. It was concluded that Monoraphidium sp. grown in USDA Hardiness Zone 5 is capable of producing biodiesel.

  13. Talc based exopolysaccharides formulation enhancing growth and production of Hellianthus annuus under saline conditions.

    PubMed

    Tewari, S; Arora, K

    2014-01-01

    Stress tolerating strain of Pseudomonas aeruginosa PF07 possessing plant growth promoting activity was screened for the production of exopolysaccharides (EPS). EPS production was monitored in the cell free culture supernatant (CFCS) and extracted EPS was further purified by thin layer chromatography. EPS producing cells were taken to design talc based formulation and its efficacy was checked on oilseed crop sunflower (Hellianthus annuus), under in vivo saline conditions (soil irrigated with 125 mM of saline water). Application of bioformulation significantly enhanced the yield and growth attributes of the plant in comparison to control (untreated seeds) under stress and non—stress conditions. Germination rate, plant length, dry weight and seed weight increased remarkably. The above findings suggest the application and benefits of utilizing EPS formulation in boosting early seedling emergence, enhancing plant growth parameters, increasing seed weight and mitigating stress in saline affected regions. Such bioformulation may enhance RAS/RT (Root Adhering Soil to Root Tissue ratio), texture of the soil, increase porosity, improve uptake of nutrients, and hence may be considered as commercially important formulation for renovation of stressed sites and enhancing plant growth. PMID:25535716

  14. Influence of growth conditions on tin incorporation in GaAs grown by molecular beam epitaxy

    SciTech Connect

    Alexandre, F.; Raisin, C.; Abdalla, M.I.; Brenac, A.; Masson, J.M.

    1980-08-01

    Intentional perturbations applied to the growth parameters of Sn-doped GaAs layers grown by molecular beam epitaxy have been performed in order to investigate the tin incorporation mechanism. The start, the interruption, and the end of growth as well as a variation of fluxes or substrate temperature have been studied, using either the Auger electron spectroscopy (AES) measurement of tin accumulation on the surface, or C-V derived free-carrier concentration profile versus any of these growth parameters. The theoretical model proposed by Wood and Joyce, based on a time-delayed incorporation mechanism, has been found to fit the observed results, especially for As-rich surface, provided that an incorporation mechanism of second order is assumed. For Ga-rich conditions (T/sub s/>580 /sup 0/C), a new result has been recognized, i.e., a significant reduction of carrier concentration as T/sub s/ is increased. The assumption of a partially acceptor nature of tin incident atoms under these growth conditions does not seem to fully explain this result. On the other hand, this may be better understood assuming a certain amount of tin atoms being re-evaporated in the high substrate temperature range. This behavior induces a temporarily weaker accumulation at the surface, and hence a relatively smaller incorporation rate.

  15. [Growth of the Orinoco Caiman (Crocodylus intermedius, Crocodylia: Crocodylidae) under two captivity conditions].

    PubMed

    Perez, Aldeima T T

    2008-03-01

    Growth of the Orinoco Caiman (Crocodylus intermedius, Crocodylia: Crocodylidae) under two captivity conditions. In order to determine the growth of Caiman of the Orinoco (Crocodylus intermedius) under two conditions of captivity, 40 specimens were raised during 11 months and 15 days in two circular tanks, with 28.3 m2 of surface area and a volume of 62.2 m3 in each tank. The tanks were built with concrete walls and guarded blocks covered internally with sheets of myrrhlike resin, and a roof of galvanized sheets. One tank was covered partially with the galvanized sheets (tank I), the other was totally covered (tank II). Twenty caimans were placed in each tank, and both groups were fed with 85% beef, 10% fresh fish, 5% hen eggs and a mixture of minerals and vitamins. The length and weight differed significantly between the groups (p < 0.001). Mean growth (103.0 +/- 6.81 cm) and weight (3 987 +/- 0.98 g) were higher in tank II, (tank I: 88.9 +/- 7.58 cm; 2 705 +/- 0.69 g). The greater growth in tank II reflects higher air and water temperatures. The survival rate was 97.5%. These results can be used for rearing caimans in captivity for conservation and commercial purposes. PMID:18624249

  16. Optimization of photobioreactor growth conditions for a cyanobacterium expressing mosquitocidal Bacillus thuringiensis Cry proteins.

    PubMed

    Ketseoglou, Irene; Bouwer, Gustav

    2013-08-10

    An Anabaena strain (PCC 7120#11) that was genetically engineered to express Bacillus thuringiensis subsp. israelensis cry genes has shown good larvicidal activity against Anopheles arabiensis, a major vector of malaria in Africa. Response surface methodology was used to evaluate the relationship between key growth factors and the volumetric productivity of PCC 7120#11 in an indoor, flat-plate photobioreactor. The interaction of input CO₂ concentration and airflow rate had a statistically significant effect on the volumetric productivity of PCC 7120#11, as did the interaction of airflow rate and photosynthetic photon flux density. Model-based numerical optimization indicated that the optimal factor level combination for maximizing PCC 7120#11 volumetric productivity was a photosynthetic photon flux density of 154 μmol m⁻² s⁻¹ and air enriched with 3.18% (v/v) CO₂ supplied at a flow rate of 1.02 vessel volumes per minute. At the levels evaluated in the study, none of the growth factors had a significant effect on the median lethal concentration of PCC 7120#11 against An. arabiensis larvae. This finding is important because loss of mosquitocidal activity under growth conditions that maximize volumetric productivity would impact on the feasibility of using PCC 7120#11 in malaria vector control programs. The study showed the usefulness of response surface methodology for determination of the optimal growth conditions for a cyanobacterium that is genetically engineered to have larvicidal activity against malaria vectors. PMID:23732832

  17. Features of Scots pine radial growth in conditions of provenance trial

    NASA Astrophysics Data System (ADS)

    Kuzmin, S.

    2012-12-01

    Provenance trial of Scots pine in Boguchany forestry of Krasnoyarsk krai is conducted on two different soils - dark-grey loam forest soil and sod-podzol sandy soil. Complex of negative factors for plant growth and development appears in dry conditions of sandy soil. It could results in decrease of resistance to diseases. Sandy soils in different climatic zones have such common traits as low absorbing capacity, poorness of elemental nutrition, low microbiological activity and moisture capacity, very high water permeability. But Scots pine trees growing in such conditions could have certain advantages and perspectives of use. In the scope of climate change (global warming) the study of Scots pine growth on sandy soil become urgent because of more frequent appearance of dry seasons. Purpose of the work is revelation of radial growth features of Scots pine with different origin in dry conditions of sandy soil and assessment of external factors influence. The main feature of radial growth of majority of studied pine provenances in conditions of sandy soil is presence of significant variation of increment with distinct decline in 25-years old with loss of tree rings in a number of cases. The reason of it is complex of factors: deficit of June precipitation and next following outbreak of fungal disease. Found «frost rings» for all trees of studied clymatypes in 1992 are the consequence of temperature decline from May 21 to June 2 - from 23 C degrees up to 2 C. Perspective climatypes with biggest radial increments and least sensitivity to fungal disease were revealed.

  18. Identification of sRNAs expressed by the human pathogen Neisseria gonorrhoeae under disparate growth conditions.

    PubMed

    McClure, Ryan; Tjaden, Brian; Genco, Caroline

    2014-01-01

    In the last several years, bacterial gene regulation via small RNAs (sRNAs) has been recognized as an important mechanism controlling expression of essential proteins that are critical to bacterial growth and metabolism. Technologies such as RNA-seq are rapidly expanding the field of sRNAs and are enabling a global view of the "sRNAome" of several bacterial species. While numerous sRNAs have been identified in a variety of both Gram-negative and Gram-positive bacteria, only a very small number have been fully characterized in the human pathogen Neisseria gonorrhoeae, the etiological agent of the STD gonorrhea. Here we present the first analysis of N. gonorrhoeae specifically focused on the identification of sRNAs through RNA-seq analysis of the organism cultured under different in vitro growth conditions. Using a new computational program, Rockhopper, to analyze prokaryotic RNA-seq data obtained from N. gonorrhoeae we identified several putative sRNAs and confirmed their expression and size through Northern blot analysis. In addition, RNA was collected from four different growth conditions (iron replete and deplete, as well as with and without co-culture with human endocervical cells). Many of the putative sRNAs identified shoed varying expression levels relative to the different growth conditions examine or were detected only under certain conditions but not others. Comparisons of identified sRNAs with the regulatory pattern of putative mRNA targets revealed possible functional roles for these sRNAs. These studies are the first to carry out a global analysis of N. gonorrhoeae specifically focused on sRNAs and show that RNA-mediated regulation may be an important mechanism of gene control in this human pathogen. PMID:25221548

  19. Characteristics of bacterial and fungal growth in plastic bottled beverages under a consuming condition model.

    PubMed

    Watanabe, Maiko; Ohnishi, Takahiro; Araki, Emiko; Kanda, Takashi; Tomita, Atsuko; Ozawa, Kazuhiro; Goto, Keiichi; Sugiyama, Kanji; Konuma, Hirotaka; Hara-Kudo, Yukiko

    2014-01-01

    Microbial contamination in unfinished beverages can occur when drinking directly from the bottle. Various microorganisms, including foodborne pathogens, are able to grow in these beverages at room temperature or in a refrigerator. In this study, we elucidated the characteristics of microorganism growth in bottled beverages under consuming condition models. Furthermore, we provide insight into the safety of partially consumed bottled beverages with respect to food hygiene. We inoculated microorganisms, including foodborne pathogens, into various plastic bottled beverages and analysed the dynamic growth of microorganisms as well as bacterial toxin production in the beverages. Eight bottled beverage types were tested in this study, namely green tea, apple juice drink, tomato juice, carbonated drink, sport drink, coffee with milk, isotonic water and mineral water, and in these beverages several microorganism types were used: nine bacteria including three toxin producers, three yeasts, and five moulds. Following inoculation, the bottles were incubated at 35°C for 48 h for bacteria, 25°C for 48 h for yeasts, and 25°C for 28 days for moulds. During the incubation period, the number of bacteria and yeasts and visible changes in mould-growth were determined over time. Our results indicated that combinations of the beverage types and microorganism species correlated with the degree of growth. Regarding factors that affect the growth and toxin-productivity of microorganisms in beverages, it is speculated that the pH, static/shaking culture, temperature, additives, or ingredients, such as carbon dioxide or organic matter (especially of plant origin), may be important for microorganism growth in beverages. Our results suggest that various types of unfinished beverages have microorganism growth and can include food borne pathogens and bacterial toxins. Therefore, our results indicate that in terms of food hygiene it is necessary to consume beverages immediately after opening

  20. Controlled growth of CNT in mesoporous AAO through optimized conditions for membrane preparation and CVD operation.

    PubMed

    Ciambelli, P; Arurault, L; Sarno, M; Fontorbes, S; Leone, C; Datas, L; Sannino, D; Lenormand, P; Du Plouy, S Le Blond

    2011-07-01

    Anodic aluminium oxide (RAAO) membranes with a mesoporous structure were prepared under strictly controlling experimental process conditions, and physically and chemically characterized by a wide range of experimental techniques. Commercial anodic aluminium oxide (CAAO) membranes were also investigated for comparison. We demonstrated that RAAO membranes have lower content of both water and phosphorus and showed better porosity shape than CAAO. The RAAO membranes were used for template growth of carbon nanotubes (CNT) inside its pores by ethylene chemical vapour deposition (CVD) in the absence of a catalyst. A composite material, containing one nanotube for each channel, having the same length as the membrane thickness and an external diameter close to the diameter of the membrane holes, was obtained. Yield, selectivity and quality of CNTs in terms of diameter, length and arrangement (i.e. number of tubes for each channel) were optimized by investigating the effect of changing the experimental conditions for the CVD process. We showed that upon thermal treatment RAAO membranes were made up of crystallized allotropic alumina phases, which govern the subsequent CNT growth, because of their catalytic activity, likely due to their Lewis acidity. The strict control of experimental conditions for membrane preparation and CNT growth allowed us to enhance the carbon structural order, which is a critical requisite for CNT application as a substitute for copper in novel nano-interconnects. PMID:21576783

  1. Controlled growth of CNT in mesoporous AAO through optimized conditions for membrane preparation and CVD operation

    NASA Astrophysics Data System (ADS)

    Ciambelli, P.; Arurault, L.; Sarno, M.; Fontorbes, S.; Leone, C.; Datas, L.; Sannino, D.; Lenormand, P.; Le Blond Du Plouy, S.

    2011-07-01

    Anodic aluminium oxide (RAAO) membranes with a mesoporous structure were prepared under strictly controlling experimental process conditions, and physically and chemically characterized by a wide range of experimental techniques. Commercial anodic aluminium oxide (CAAO) membranes were also investigated for comparison. We demonstrated that RAAO membranes have lower content of both water and phosphorus and showed better porosity shape than CAAO. The RAAO membranes were used for template growth of carbon nanotubes (CNT) inside its pores by ethylene chemical vapour deposition (CVD) in the absence of a catalyst. A composite material, containing one nanotube for each channel, having the same length as the membrane thickness and an external diameter close to the diameter of the membrane holes, was obtained. Yield, selectivity and quality of CNTs in terms of diameter, length and arrangement (i.e. number of tubes for each channel) were optimized by investigating the effect of changing the experimental conditions for the CVD process. We showed that upon thermal treatment RAAO membranes were made up of crystallized allotropic alumina phases, which govern the subsequent CNT growth, because of their catalytic activity, likely due to their Lewis acidity. The strict control of experimental conditions for membrane preparation and CNT growth allowed us to enhance the carbon structural order, which is a critical requisite for CNT application as a substitute for copper in novel nano-interconnects.

  2. Spherulitic Growth of Hematite Under Hydrothermal Conditions: Insights into the Growth Mechanism of Hematite Spherules at Meridiani Planum Mars.

    NASA Technical Reports Server (NTRS)

    Ming, Douglas W.; Golden, D. C.; Morris, R. V.

    2010-01-01

    Hematite-rich spherules were discovered embedded in sulfate-rich outcrop rock and as lag deposits of whole and broken spherules by the Opportunity rover at Meridiani Planem [1-6]. The Mars Global Surveyor (MGS) Thermal Emission Spectrometer (TES), which has a wider spectral range compared to the Mars Exploration Rover Mini-TES, provided an important constraint that hematite-rich spherules are dominated by emission along the crystallographic c-axis [7-10]. We have previously synthesized hematite spherules whose mineralogic, chemical, and crystallographic properties are strikingly similar to those for the hematite-rich spherules at Meridiani Planum [11]. The spherules were synthesized in the laboratory along with hydronium jarosite and minor hydronium alunite from Fe-Al-Mg-S-Cl acid sulfate solutions under hydrothermal conditions. The reaction sequence was (1) precipitation of hydronium jarosite, (2) jarosite dissolution and precipitation of hematite spherules, and (3) precipitation of hydronium alunite upon depletion of hydronium jarosite. The spherules exhibit a radial growth texture with the crystallographic c-axis aligned along the radial direction, so that thermal emission spectra have no hematite emissivity minimum at approx.390/cm similar to the emission spectra returned by MGS TES. The objective of this paper is to expand on our initial studies [11] to examine the morphological evolution during growth of spherules starting from sub-micrometer crystals to spherules many orders of magnitude in size.

  3. Mathematical modeling of growth of Salmonella in raw ground beef under isothermal conditions from 10 to 45 Degree C

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this study was to develop primary and secondary models to describe the growth of Salmonella in raw ground beef. Primary and secondary models can be integrated into a dynamic model that can predict the microbial growth under varying environmental conditions. Growth data of Salmonel...

  4. Mathematical modeling of the effects of aerobic and anaerobic chelate bioegradation on actinide speciation.

    SciTech Connect

    Banaszak, J.E.; VanBriesen, J.; Rittmann, B.E.; Reed, D.T.

    1998-03-19

    Biodegradation of natural and anthropogenic chelating agents directly and indirectly affects the speciation, and, hence, the mobility of actinides in subsurface environments. We combined mathematical modeling with laboratory experimentation to investigate the effects of aerobic and anaerobic chelate biodegradation on actinide [Np(IV/V), Pu(IV)] speciation. Under aerobic conditions, nitrilotriacetic acid (NTA) biodegradation rates were strongly influenced by the actinide concentration. Actinide-chelate complexation reduced the relative abundance of available growth substrate in solution and actinide species present or released during chelate degradation were toxic to the organisms. Aerobic bio-utilization of the chelates as electron-donor substrates directly affected actinide speciation by releasing the radionuclides from complexed form into solution, where their fate was controlled by inorganic ligands in the system. Actinide speciation was also indirectly affected by pH changes caused by organic biodegradation. The two concurrent processes of organic biodegradation and actinide aqueous chemistry were accurately linked and described using CCBATCH, a computer model developed at Northwestern University to investigate the dynamics of coupled biological and chemical reactions in mixed waste subsurface environments. CCBATCH was then used to simulate the fate of Np during anaerobic citrate biodegradation. The modeling studies suggested that, under some conditions, chelate degradation can increase Np(IV) solubility due to carbonate complexation in closed aqueous systems.

  5. A Time-Dependent Numerical Model for Spherically Symmetric Hailstone Growth Thermodynamics under Constant Ambient Conditions.

    NASA Astrophysics Data System (ADS)

    Lozowski, E. P.; D'Amours, R.

    1980-08-01

    A model of spherical hailstone growth thermodynamics is presented, and used to examine the validity of the continuous growth and heat balance assumptions frequently employed in the `classical' hail growth models. The model is similar to the spherically symmetric model formulated by Macklin and Payne (1969), but solutions to the model equations are obtained by means of finite-difference numerical methods. In the model, we do not try to simulate the discrete accretion process of individual drops. Instead, we attempt to identify the implications of the discrete, time-dependent nature of the icing process, by examining the accretion of a thin uniform layer of supercooled water over the entire surface of the sphere. The heat transfer equations both with the air and within the hailstone axe then solved assuming radial symmetry. By the addition of several such layers, the finite growth of a spherical hailstone can be simulated. In the present paper, only growth in constant ambient conditions is considered. It is shown that there are large internal heat fluxes during the interval between the accretion of successive layers (typically 1 s), which cause the temperatures near the surface to oscillate several degrees above and below their time-mean value. Nevertheless, the time-averaged temperature over an accretion cycle is almost uniform throughout the hailstone and, when the environmental conditions are constant, is approximately equal to the equilibrium surface temperature predicted by the `classical' models. As the hailstone grows under constant environmental conditions, it continually adapts to the classical equilibrium temperature, warming up almost uniformly throughout. The time scale for this adjustment to a quasi-equilibrium state is found to be of the order of the internal diffusive time scale R2/k. It is speculated therefore that if the environmental conditions change slowly (over time scales large compared with R2/k) the hailstone thermodynamics will be adequately

  6. Tree growth and forest ecosystem functioning in Eurasia under extreme climate conditions

    NASA Astrophysics Data System (ADS)

    Saurer, Matthias; Kirdyanov, Alexander; Prokushkin, Anatoly; Bryukhanova, Marina; Knorre, Anastasia; Nasyrov, Muhtor; Frank, David; Treydte, Kerstin; Sidorova, Olga; Siegwolf, Rolf

    2013-04-01

    The main goal of this study is to improve our understanding of the influence of a changing climate on trees in extreme conditions by a detailed analysis of the factors controlling tree-ring growth. We investigated forest ecosystems in regions that are very sensitive to climatic changes and where rapid and dramatic environmental and climatic changes are on-going, namely, the high latitude permafrost region in Central Siberia (Russia), the semi-arid dry areas in Central Asia (Uzbekistan) and high-altitude sites in the Alps (Switzerland). Tree-ring parameters studied were ring-width, density, cell number and structure and the ratio of carbon and oxygen isotopes. An important aspect of the work was the characterization of seasonal growth and water supply of trees. Intra-seasonal dynamics of tree-ring formation was correlated with monitored environmental factors, such as air and soil temperature and moisture, permafrost depth and the isotope composition of soil water, of precipitation, and of stream water. Intra-annual and long-term variability of the main tree-ring parameters were compared for the different regions. The results obtained help us to understand better tree-physiological processes valid under contrasting environmental conditions. For instance, the relationship between the onset of cell division in the cambium and the thermo-hydrological soil regime was used to determine the period of the year with the highest influence on the start of tree-ring formation. Seasonally resolved oxygen isotope depth profiles of soil water and concurrent xylem and leaf water measurements show the importance of time-lags between precipitation, leaf processes and growth. The data obtained are important for improving tree-ring growth models and estimating future tree growth under climate change. Funding: SNF SCOPES IZ73Z0_128035

  7. Rates of Root and Organism Growth, Soil Conditions, and Temporal and Spatial Development of the Rhizosphere

    PubMed Central

    WATT, MICHELLE; SILK, WENDY K.; PASSIOURA, JOHN B.

    2006-01-01

    • Background Roots growing in soil encounter physical, chemical and biological environments that influence their rhizospheres and affect plant growth. Exudates from roots can stimulate or inhibit soil organisms that may release nutrients, infect the root, or modify plant growth via signals. These rhizosphere processes are poorly understood in field conditions. • Scope and Aims We characterize roots and their rhizospheres and rates of growth in units of distance and time so that interactions with soil organisms can be better understood in field conditions. We review: (1) distances between components of the soil, including dead roots remnant from previous plants, and the distances between new roots, their rhizospheres and soil components; (2) characteristic times (distance2/diffusivity) for solutes to travel distances between roots and responsive soil organisms; (3) rates of movement and growth of soil organisms; (4) rates of extension of roots, and how these relate to the rates of anatomical and biochemical ageing of root tissues and the development of the rhizosphere within the soil profile; and (5) numbers of micro-organisms in the rhizosphere and the dependence on the site of attachment to the growing tip. We consider temporal and spatial variation within the rhizosphere to understand the distribution of bacteria and fungi on roots in hard, unploughed soil, and the activities of organisms in the overlapping rhizospheres of living and dead roots clustered in gaps in most field soils. • Conclusions Rhizosphere distances, characteristic times for solute diffusion, and rates of root and organism growth must be considered to understand rhizosphere development. Many values used in our analysis were estimates. The paucity of reliable data underlines the rudimentary state of our knowledge of root–organism interactions in the field. PMID:16551700

  8. Simulating crop growth with Expert-N-GECROS under different site conditions in Southwest Germany

    NASA Astrophysics Data System (ADS)

    Poyda, Arne; Ingwersen, Joachim; Demyan, Scott; Gayler, Sebastian; Streck, Thilo

    2016-04-01

    When feedbacks between the land surface and the atmosphere are investigated by Atmosphere-Land surface-Crop-Models (ALCM) it is fundamental to accurately simulate crop growth dynamics as plants directly influence the energy partitioning at the plant-atmosphere interface. To study both the response and the effect of intensive agricultural crop production systems on regional climate change in Southwest Germany, the crop growth model GECROS (YIN & VAN LAAR, 2005) was calibrated based on multi-year field data from typical crop rotations in the Kraichgau and Swabian Alb regions. Additionally, the SOC (soil organic carbon) model DAISY (MÜLLER et al., 1998) was implemented in the Expert-N model tool (ENGEL & PRIESACK, 1993) and combined with GECROS. The model was calibrated based on a set of plant (BBCH, LAI, plant height, aboveground biomass, N content of biomass) and weather data for the years 2010 - 2013 and validated with the data of 2014. As GECROS adjusts the root-shoot partitioning in response to external conditions (water, nitrogen, CO2), it is suitable to simulate crop growth dynamics under changing climate conditions and potentially more frequent stress situations. As C and N pools and turnover rates in soil as well as preceding crop effects were expected to considerably influence crop growth, the model was run in a multi-year, dynamic way. Crop residues and soil mineral N (nitrate, ammonium) available for the subsequent crop were accounted for. The model simulates growth dynamics of winter wheat, winter rape, silage maize and summer barley at the Kraichgau and Swabian Alb sites well. The Expert-N-GECROS model is currently parameterized for crops with potentially increasing shares in future crop rotations. First results will be shown.

  9. Sequential anaerobic/aerobic biotreatment of bark leachate.

    PubMed

    Frigon, J C; Cimpoia, R; Guiot, S R

    2003-01-01

    Bark leachate is generated from sawmill operations such as log storage sites and contains polymeric tannins, carbohydrates, organic acids, phenolic and resin compounds. The present study was aimed at assessing the performance of a sequential anaerobic and aerobic treatment, for both chemical oxygen demand (COD) and phenol removal, under various combinations of operational conditions, in the continuous mode. After anaerobic treatment in a five litres upflow anaerobic sludge bed (UASB) reactor, the leachate was directed into two parallel aerobic reactors, either an activated sludge unit or a fixed film submerged filter (packed with polyethylene Flexirings), both of a volume of one litre and oxygenated by air diffusion. For a leachate of 22 gCOD/l, an overall COD removal of 96-98% was achieved at an hydraulic residence time (HRT) of 4 days for the anaerobic reactor and one day for either aerobic systems. The phenol concentration generally increased after anaerobic treatment but was below the detection limit (50 ppb) after aerobic polishing. Radiorespirometric microcosms with 14C-labelled phenol confirmed that phenol was mineralized in the aerobic reactors. The performances of both aerobic systems were similar for COD and phenol removal. Thus, a sequential anaerobic/aerobic treatment was able to effectively address the contamination of a bark leachate discharge, including phenols. PMID:14640219

  10. High-quality and high-purity homoepitaxial diamond (100) film growth under high oxygen concentration condition

    SciTech Connect

    Teraji, Tokuyuki

    2015-09-21

    Defect formation during diamond homoepitaxial growth was sufficiently inhibited by adding oxygen simultaneously in the growth ambient with high concentration of 2%. A 30-μm thick diamond films with surface roughness of <2 nm were homoepitaxially deposited on the (100) diamond single crystal substrates with reasonable growth rate of approximately 3 μm h{sup −1} under the conditions of higher methane concentration of 10%, higher substrate temperature of ∼1000 °C, and higher microwave power density condition of >100 W cm{sup −3}. Surface characteristic patterns moved to an identical direction with growth thickness, indicating that lateral growth was dominant growth mode. High chemical purity represented by low nitrogen concentration of less than 1 ppb and the highest {sup 12}C isotopic ratio of 99.998% of the obtained homoepitaxial diamond (100) films suggest that the proposed growth condition has high ability of impurity control.

  11. Aerobic Fitness and School Children.

    ERIC Educational Resources Information Center

    Hinkle, J. Scott

    1997-01-01

    Provides school counselors with information on aerobic exercise (specifically running) and the psychological, behavioral, and physical benefits children obtained by participating in fitness programs. Recommends collaboration between school counselors and physical education teachers and gives a preliminary discussion of aerobic running and its…

  12. Aerobic Fitness and School Children.

    ERIC Educational Resources Information Center

    Hinkle, J. Scott

    1992-01-01

    Provides school counselors with information regarding aerobic exercise (specifically running), and the psychological, behavioral, and physical benefits children obtain by participating in fitness programs. Presents methods of collaboration between school counselors and physical education teachers. Offers preliminary discussion of aerobic running…

  13. Exercise, Animal Aerobics, and Interpretation?

    ERIC Educational Resources Information Center

    Oliver, Valerie

    1996-01-01

    Describes an aerobic activity set to music for children that mimics animal movements. Example exercises include walking like a penguin or jumping like a cricket. Stresses basic aerobic principles and designing the program at the level of children's motor skills. Benefits include reaching people who normally don't visit nature centers, and bridging…

  14. Optimization of plant mineral nutrition under growth-limiting conditions in a lunar greenhouse

    NASA Astrophysics Data System (ADS)

    Zaets, I.; Voznyuk, T.; Kovalchuk, M.; Rogutskyy, I.; Lukashov, D.; Mytrokhyn, O.; Mashkovska, S.; Foing, B.; Kozyrovska, N.

    It may be assumed that the first plants in a lunar base will play a main role in forming a protosoil of acceptable fertility needed for purposively growing second generation plants like wheat, rice, tulips, etc. The residues of the first-generation plants could be composted and transformed by microorganisms into a soil-like substrate within a loop of regenerative life support system. The lunar regolith may be used as a substrate for plant growth at the very beginning of a mission to reduce its cost. The use of microbial communities for priming plants will allow one to facilitate adaption to stressful conditions and to support the plant development under growth limiting conditions. Well-defined plant-associated bacteria were used for growing three cultivars to colonize French marigold (Tagetes patula L.) in anorthosite, a substrate of low bioavailability, analogous to a lunar rock. The consortium was composed of plant growth promoting rhizobacteria and the bacterium Paenibacillus sp. IMBG156 which stimulated seed germination, better plant development, and finally, the flowering of inoculated tagetes. In contrast, control plants grew poorly in the anorthosite and practically did not survive until flowering. Analysis of bacterial community composition showed that all species colonized plant roots, however, the rate of colonization depended on the allelopatic characteristics of marigold varieties. Bacteria of consortium were able to liberate some elements (Ca, Fe, Mn, Si, Ni, Cu, Zn) from substrate anorthosite. Plant colonization by mixed culture of bacterial strains resulted in the increase of accumulation of K, Mg, Mn by the plant and in the lowering of the level of toxic metal accumulation. It was assumed that a rationally assembled consortium of bacterial strains promoted germination of marygold seeds and supported the plant development under growth limiting conditions by means of bioleaching plant essential nutritional elements and by protecting the plant against

  15. Effect of ocean acidification on growth and otolith condition of juvenile scup, Stenotomus chrysops.

    PubMed

    Perry, Dean M; Redman, Dylan H; Widman, James C; Meseck, Shannon; King, Andrew; Pereira, Jose J

    2015-09-01

    Increasing amounts of atmospheric carbon dioxide (CO2) from human industrial activities are causing changes in global ocean carbonate chemistry, resulting in a reduction in pH, a process termed "ocean acidification." It is important to determine which species are sensitive to elevated levels of CO2 because of potential impacts to ecosystems, marine resources, biodiversity, food webs, populations, and effects on economies. Previous studies with marine fish have documented that exposure to elevated levels of CO2 caused increased growth and larger otoliths in some species. This study was conducted to determine whether the elevated partial pressure of CO2 (pCO2) would have an effect on growth, otolith (ear bone) condition, survival, or the skeleton of juvenile scup, Stenotomus chrysops, a species that supports both important commercial and recreational fisheries. Elevated levels of pCO2 (1200-2600 μatm) had no statistically significant effect on growth, survival, or otolith condition after 8 weeks of rearing. Field data show that in Long Island Sound, where scup spawn, in situ levels of pCO2 are already at levels ranging from 689 to 1828 μatm due to primary productivity, microbial activity, and anthropogenic inputs. These results demonstrate that ocean acidification is not likely to cause adverse effects on the growth and survivability of every species of marine fish. X-ray analysis of the fish revealed a slightly higher incidence of hyperossification in the vertebrae of a few scup from the highest treatments compared to fish from the control treatments. Our results show that juvenile scup are tolerant to increases in seawater pCO2, possibly due to conditions this species encounters in their naturally variable environment and their well-developed pH control mechanisms. PMID:26442471

  16. Winter feeding, growth and condition of brown trout Salmo trutta in a groundwater-dominated stream

    USGS Publications Warehouse

    French, William E.; Vondracek, Bruce C.; Ferrington, Leonard C., Jr.; Finlay, Jacques C.; Dieterman, Douglas J.

    2014-01-01

    Winter can be a stressful period for stream-dwelling salmonid populations, often resulting in reduced growth and survival. Stream water temperatures have been identified as a primary mechanism driving reductions in fitness during winter. However, groundwater inputs can moderate water temperature and may reduce winter severity. Additionally, seasonal reductions in prey availability may contribute to decreased growth and survival, although few studies have examined food webs supporting salmonids under winter conditions. This study employed diet, stable isotope, and mark-recapture techniques to examine winter (November through March) feeding, growth, and condition of brown troutSalmo trutta in a groundwater-dominated stream (Badger Creek, Minnesota, USA). Growth was greater for fish ≤ 150 mm (mean = 4.1 mg g−1 day−1) than for those 151–276 mm (mean = 1.0 mg g−1 day−1) during the winter season. Overall condition from early winter to late winter did not vary for fish ≤150 mm (mean relative weight (Wr) = 89.5) and increased for those 151–276 mm (mean Wr = 85.8 early and 89.4 late). Although composition varied both temporally and by individual, brown trout diets were dominated by aquatic invertebrates, primarily Amphipods, Dipterans, and Trichopterans. Stable isotope analysis supported the observations of the dominant prey taxa in stomach contents and indicated the winter food web was supported by a combination of allochthonous inputs and aquatic macrophytes. Brown trout in Badger Creek likely benefited from the thermal regime and increased prey abundance present in this groundwater-dominated stream during winter.

  17. Conditional Cooperativity of Toxin - Antitoxin Regulation Can Mediate Bistability between Growth and Dormancy

    PubMed Central

    Cataudella, Ilaria; Sneppen, Kim; Gerdes, Kenn; Mitarai, Namiko

    2013-01-01

    Many toxin-antitoxin operons are regulated by the toxin/antitoxin ratio by mechanisms collectively coined “conditional cooperativity”. Toxin and antitoxin form heteromers with different stoichiometric ratios, and the complex with the intermediate ratio works best as a transcription repressor. This allows transcription at low toxin level, strong repression at intermediate toxin level, and then again transcription at high toxin level. Such regulation has two interesting features; firstly, it provides a non-monotonous response to the concentration of one of the proteins, and secondly, it opens for ultra-sensitivity mediated by the sequestration of the functioning heteromers. We explore possible functions of conditional regulation in simple feedback motifs, and show that it can provide bistability for a wide range of parameters. We then demonstrate that the conditional cooperativity in toxin-antitoxin systems combined with the growth-inhibition activity of free toxin can mediate bistability between a growing state and a dormant state. PMID:24009488

  18. Conditional cooperativity of toxin - antitoxin regulation can mediate bistability between growth and dormancy.

    PubMed

    Cataudella, Ilaria; Sneppen, Kim; Gerdes, Kenn; Mitarai, Namiko

    2013-01-01

    Many toxin-antitoxin operons are regulated by the toxin/antitoxin ratio by mechanisms collectively coined "conditional cooperativity". Toxin and antitoxin form heteromers with different stoichiometric ratios, and the complex with the intermediate ratio works best as a transcription repressor. This allows transcription at low toxin level, strong repression at intermediate toxin level, and then again transcription at high toxin level. Such regulation has two interesting features; firstly, it provides a non-monotonous response to the concentration of one of the proteins, and secondly, it opens for ultra-sensitivity mediated by the sequestration of the functioning heteromers. We explore possible functions of conditional regulation in simple feedback motifs, and show that it can provide bistability for a wide range of parameters. We then demonstrate that the conditional cooperativity in toxin-antitoxin systems combined with the growth-inhibition activity of free toxin can mediate bistability between a growing state and a dormant state. PMID:24009488

  19. Modeling of Macroscopic/Microscopic Transport and Growth Phenomena in Zeolite Crystal Solutions Under Microgravity Conditions

    NASA Technical Reports Server (NTRS)

    Gatsonis, Nikos A.; Alexandrou, Andreas; Shi, Hui; Ongewe, Bernard; Sacco, Albert, Jr.

    1999-01-01

    Crystals grown from liquid solutions have important industrial applications. Zeolites, for instance, a class of crystalline aluminosilicate materials, form the backbone of the chemical process industry worldwide, as they are used as adsorbents and catalysts. Many of the phenomena associated with crystal growth processes are not well understood due to complex microscopic and macroscopic interactions. Microgravity could help elucidate these phenomena and allow the control of defect locations, concentration, as well as size of crystals. Microgravity in an orbiting spacecraft could help isolate the possible effects of natural convection (which affects defect formation) and minimize sedimentation. In addition, crystals will stay essentially suspended in the nutrient pool under a diffusion-limited growth condition. This is expected to promote larger crystals by allowing a longer residence time in a high-concentration nutrient field. Among other factors, the crystal size distribution depends on the nucleation rate and crystallization. These two are also related to the "gel" polymerization/depolymerization rate. Macroscopic bulk mass and flow transport and especially gravity, force the crystals down to the bottom of the reactor, thus forming a sedimentation layer. In this layer, the growth rate of the crystals slows down as crystals compete for a limited amount of nutrients. The macroscopic transport phenomena under certain conditions can, however, enhance the nutrient supply and therefore, accelerate crystal growth. Several zeolite experiments have been performed in space with mixed results. The results from our laboratory have indicated an enhancement in size of 30 to 70 percent compared to the best ground based controls, and a reduction of lattice defects in many of the space grown crystals. Such experiments are difficult to interpret, and cannot be easily used to derive empirical or other laws since many physical parameters are simultaneously involved in the process

  20. Biocontrol agents promote growth of potato pathogens, depending on environmental conditions.

    PubMed

    Cray, Jonathan A; Connor, Mairéad C; Stevenson, Andrew; Houghton, Jonathan D R; Rangel, Drauzio E N; Cooke, Louise R; Hallsworth, John E

    2016-05-01

    There is a pressing need to understand and optimize biological control so as to avoid over-reliance on the synthetic chemical pesticides that can damage environmental and human health. This study focused on interactions between a novel biocontrol-strain, Bacillus sp. JC12GB43, and potato-pathogenic Phytophthora and Fusarium species. In assays carried out in vitro and on the potato tuber, the bacterium was capable of near-complete inhibition of pathogens. This Bacillus was sufficiently xerotolerant (water activity limit for growth = 0.928) to out-perform Phytophthora infestans (~0.960) and challenge Fusarium coeruleum (~0.847) and Fusarium sambucinum (~0.860) towards the lower limits of their growth windows. Under some conditions, however, strain JC12GB43 stimulated proliferation of the pathogens: for instance, Fusarium coeruleum growth-rate was increased under chaotropic conditions in vitro (132 mM urea) by >100% and on tubers (2-M glycerol) by up to 570%. Culture-based assays involving macromolecule-stabilizing (kosmotropic) compatible solutes provided proof-of-principle that the Bacillus may provide kosmotropic metabolites to the plant pathogen under conditions that destabilize macromolecular systems of the fungal cell. Whilst unprecedented, this finding is consistent with earlier reports that fungi can utilize metabolites derived from bacterial cells. Unless the antimicrobial activities of candidate biocontrol strains are assayed over a full range of field-relevant parameters, biocontrol agents may promote plant pathogen infections and thereby reduce crop yields. These findings indicate that biocontrol activity, therefore, ought to be regarded as a mode-of-behaviour (dependent on prevailing conditions) rather than an inherent property of a bacterial strain. PMID:26880001

  1. Effect of growth conditions on microbial activity and iron-sulfide production by Desulfovibrio vulgaris.

    PubMed

    Zhou, Chen; Vannela, Raveender; Hayes, Kim F; Rittmann, Bruce E

    2014-05-15

    Sulfate-reducing bacteria (SRB) can produce iron sulfide (FeS) solids with mineralogical characteristics that may be beneficial for a variety of biogeochemical applications, such as long-term immobilization of uranium. In this study, the growth and metabolism of Desulfovibrio vulgaris, one of the best-studied SRB species, were comprehensively monitored in batch studies, and the biogenic FeS solids were characterized by X-ray diffraction. Controlling the pH by varying the initial pH, the iron-to-sulfate ratio, or the electron donor - affected the growth of D. vulgaris and strongly influenced the formation and growth of FeS solids. In particular, lower pH (from initial conditions or a decrease caused by less sulfate reduction, FeS precipitation, or using pyruvate as the electron donor) produced larger-sized mackinawite (Fe1+xS). Greater accumulation of free sulfide, from more sulfate reduction by D. vulgaris, also led to larger-sized mackinawite and particularly stimulated mackinawite transformation to greigite (Fe3S4) when the free sulfide concentration was 29.3mM. Furthermore, sufficient free Fe(2+) led to the additional formation of vivianite [Fe3(PO4)2·8(H2O)]. Thus, microbially relevant conditions (initial pH, choice of electron donor, and excess or deficiency of sulfide) are tools to generate biogenic FeS solids of different characteristics. PMID:24675611

  2. Survival, growth and condition of freshwater mussels: effects of municipal wastewater effluent.

    PubMed

    Nobles, Trey; Zhang, Yixin

    2015-01-01

    Freshwater mussels (Family Unionidae) are among the most imperiled group of organisms in the world, with nearly 65% of North American species considered endangered. Anthropogenic disturbances, including altered flow regimes, habitat alteration, and pollution, are the major driver of this group's decline. We investigated the effects of tertiary treated municipal wastewater effluent on survivorship, growth, and condition of freshwater mussels in experimental cages in a small Central Texas stream. We tested the effluent effects by measuring basic physical parameters of native three ridge mussels (Amblema plicata) and of non-native Asian clams (Corbicula fluminea), before and after 72-day exposure at four sites above and below a municipal wastewater treatment plant outfall. Survivorship and growth of the non-native Asian clams and growth and condition indices of the native three ridge mussels were significantly higher at the reference site above the outfall than in downstream sites. We attribute this reduction in fitness below the outfall to elevated nutrient and heavy metal concentrations, and the potential presence of other untested-for compounds commonly found in municipal effluent. These results, along with an absence of native mussels below the discharge, indicate a significant negative impact of wastewater effluent on both native and non-native mussels in the stream. PMID:26042840

  3. Survival, Growth and Condition of Freshwater Mussels: Effects of Municipal Wastewater Effluent

    PubMed Central

    Nobles, Trey; Zhang, Yixin

    2015-01-01

    Freshwater mussels (Family Unionidae) are among the most imperiled group of organisms in the world, with nearly 65% of North American species considered endangered. Anthropogenic disturbances, including altered flow regimes, habitat alteration, and pollution, are the major driver of this group's decline. We investigated the effects of tertiary treated municipal wastewater effluent on survivorship, growth, and condition of freshwater mussels in experimental cages in a small Central Texas stream. We tested the effluent effects by measuring basic physical parameters of native three ridge mussels (Amblema plicata) and of non-native Asian clams (Corbicula fluminea), before and after 72-day exposure at four sites above and below a municipal wastewater treatment plant outfall. Survivorship and growth of the non-native Asian clams and growth and condition indices of the native three ridge mussels were significantly higher at the reference site above the outfall than in downstream sites. We attribute this reduction in fitness below the outfall to elevated nutrient and heavy metal concentrations, and the potential presence of other untested-for compounds commonly found in municipal effluent. These results, along with an absence of native mussels below the discharge, indicate a significant negative impact of wastewater effluent on both native and non-native mussels in the stream. PMID:26042840

  4. A review on the effects of environmental conditions on growth and toxin production of Ostreopsis ovata.

    PubMed

    Pistocchi, R; Pezzolesi, L; Guerrini, F; Vanucci, S; Dell'aversano, C; Fattorusso, E

    2011-03-01

    Since the end of the 1990s the occurrence of blooms of the benthic dinoflagellates Ostreopsis spp. is spreading in many tropical and temperate regions worldwide, sometimes causing benthonic biocenosis suffering and occasional human distress. Ostreopsis ovata has been found to produce palytoxin-like compounds, a class of highly potent toxins. As general, the highest abundances of Ostreopsis spp. are recorded during warmer periods characterized by high temperature, salinity, and water column stability. Moreover, as these cells are easily resuspended in the water column, the role of hydrodynamism in the blooms development and decline has been highlighted. The environmental conditions appear, therefore, to be one of the main factors determining the proliferation of these species as testified by several field surveys. Laboratory studies on the effect of environmental parameters on growth and toxicity of O. ovata are rather scarce. With regard to the effects of temperature, culture results indicate that different strains blooming along Italian coasts displayed different optima, in accordance to blooming periods, and that higher toxin levels correlated with best growth conditions. Additionally, in relation to an Adriatic strain, cell growth positively correlated with the increase in salinity, while toxicity was lowest at the highest salinity value (i.e. 40). For the same strain, both nitrogen and phosphorus limitation determined a decrease in cell toxicity showing different behaviour with respect to many other toxic dinoflagellates. PMID:20920514

  5. Heterogeneous nucleation and growth of water vapor on meteoric smoke particle analogues at mesospheric conditions

    NASA Astrophysics Data System (ADS)

    Nachbar, Mario; Duft, Denis; Leisner, Thomas

    2016-04-01

    Sub 2 nm meteoric smoke particles (MSP) produced from the ablation and recondensation of meteoric material are believed to be the major kind of nuclei causing the formation of water ice particles in the mesopause of Earth at heights of 80-90 km. These so called noctiLucent clouds (NLC) are frequently detected during polar summer, whereas the microphysical nucleation process and subsequent growth on such small particles are understood only poorly. Parameterizing these processes results in large uncertainties especially due to a lack of experimental data on desorption energies and critical saturation for the activation of nucleation under realistic mesospheric conditions, which states the need of laboratory measurements. We produce charged nanometer sized (2-3 nm) MSP analogues in a microwave plasma particle source and transfer them to a novel linear ion trap which allows us to trap the particles under typical mesospheric temperatures and H2O concentrations. The adsorption of H2O molecules on the particles surface followed by nucleation and growth can be examined by analyzing the mass distribution of the particles with a time-of-flight mass spectrometer as function of the residence time under supersaturated conditions. In this contribution we present such measurements for single positively as well as negatively charged particles which allow us to determine the desorption energy of water vapor on the investigated nanoparticles as well as the critical saturation needed to activate nucleation and subsequent growth.

  6. Response of the bacterial symbiont Holospora caryophila to different growth conditions of its host.

    PubMed

    Castelli, Michele; Lanzoni, Olivia; Fokin, Sergei I; Schrallhammer, Martina; Petroni, Giulio

    2015-02-01

    Previous studies on bacterial symbionts of ciliates have shown that some symbionts can be maintained relatively well under standard laboratory conditions whereas others are frequently lost, especially when the host is cultivated at a high division rate. In this study, the variation in infection level by the endosymbiont Holospora caryophila within its host population Paramecium octaurelia was investigated in response to three alimentary treatments and a subsequent starvation phase. The response of the ciliates was determined as a nearly exponential growth rate with different slopes in each treatment, proportional to the amount of food received. The initial infection level was higher than 90%. After 24 days of exponential host's growth, the prevalence remained stable at approximately 90% in all treatments, even after a subsequent starvation phase of 20 days. However, at intermediate time-points in both the feeding and the starvation phase, fluctuations in the presence of the intracellular bacteria were observed. These results show that H. caryophila is able to maintain its infection under the tested range of host growth conditions, also due to the possibility of an effective re-infection in case of partial loss. PMID:25635695

  7. Analyses of Fatigue Crack Growth and Closure Near Threshold Conditions for Large-Crack Behavior

    NASA Technical Reports Server (NTRS)

    Newman, J. C., Jr.

    1999-01-01

    A plasticity-induced crack-closure model was used to study fatigue crack growth and closure in thin 2024-T3 aluminum alloy under constant-R and constant-K(sub max) threshold testing procedures. Two methods of calculating crack-opening stresses were compared. One method was based on a contact-K analyses and the other on crack-opening-displacement (COD) analyses. These methods gave nearly identical results under constant-amplitude loading, but under threshold simulations the contact-K analyses gave lower opening stresses than the contact COD method. Crack-growth predictions tend to support the use of contact-K analyses. Crack-growth simulations showed that remote closure can cause a rapid rise in opening stresses in the near threshold regime for low-constraint and high applied stress levels. Under low applied stress levels and high constraint, a rise in opening stresses was not observed near threshold conditions. But crack-tip-opening displacement (CTOD) were of the order of measured oxide thicknesses in the 2024 alloy under constant-R simulations. In contrast, under constant-K(sub max) testing the CTOD near threshold conditions were an order-of-magnitude larger than measured oxide thicknesses. Residual-plastic deformations under both constant-R and constant-K(sub max) threshold simulations were several times larger than the expected oxide thicknesses. Thus, residual-plastic deformations, in addition to oxide and roughness, play an integral part in threshold development.

  8. A spectroscopy-based detector to monitor tomato growth condition in greenhouse

    NASA Astrophysics Data System (ADS)

    Yang, Ce; Li, Minzan; Cui, Di

    2008-12-01

    A spectroscopy-based detector is developed to measure the nitrogen and chlorophyll content of tomato leaves and then to predict the growth condition of tomato plants in greenhouse. The detector uses two wavebands, 527 nm and 762 nm, since it is proved that these wavebands are sensitive to nitrogen and chlorophyll content in plant leaves by previous field test. The detector contains: A Y-type optic fiber, two silicon photocells, a signal processing unit, and a MCU. Light reflection from tomato leaves is transmitted by the Y-type optic fiber to the surface of the silicon photo cells, which transfer optical signal into electrical signal. Then the analog signal is amplified to conform to the TTL level signal standard and finally converted to digital signal by MAX186. After that, the MCU carries on a series of actions, including data calculating, displaying and storage. Using the measured data, the Normalized Difference Vegetation Index (NDVI) is calculated to estimate the nitrogen and chlorophyll content in plant leaves. The result is directly displayed on an LCD screen. Users have an option in saving data, either into a USB-memory stick or into a database over the PC serial port. The detector is portable, inexpensive, and convenient, which make it meet farmers' need in China. The performance test shows that the growth model works very well, and the device has high accuracy in predicting the growth condition of tomato plants in greenhouse.

  9. Growth of oil accumulating microalga Neochloris oleoabundans under alkaline-saline conditions.

    PubMed

    Santos, A M; Janssen, M; Lamers, P P; Evers, W A C; Wijffels, R H

    2012-01-01

    The effect of elevated pH and salt concentration on the growth of the freshwater microalga Neochloris oleoabundans was investigated. A study was conducted in 24-well plates on the design of a growth medium and subsequently applied in a photobioreactor. An artificial seawater medium with reduced Ca(2+) and PO(4)(3-) could prevent mineral precipitation at high pH levels. Growth was characterized in this new medium at pH 8.1 and at pH 10.0, with 420 mM of total salts. Specific growth rates of 0.08 h(-1) at pH 8.1 and 0.04 h(-1) at pH 10.0 were obtained under controlled turbidostat cultivation. The effect of nitrogen starvation on lipid accumulation was also investigated. Fatty acids content increased not only with nitrogen limitation but also with a pH increase (up to 35% in the dry biomass). Fluorescence microscopy gave visual proof that N. oleoabundans accumulates oil bodies when growing in saline conditions at high pH. PMID:22115529

  10. Mathematical model of Chlorella minutissima UTEX2341 growth and lipid production under photoheterotrophic fermentation conditions

    PubMed Central

    Yang, JinShui; Rasa, Ehsan; Tantayotai, Prapakorn; Scow, Kate M.; Yuan, HongLi; Hristova, Krassimira R.

    2012-01-01

    To reduce the cost of algal biomass production, mathematical model was developed for the first time to describe microalgae growth, lipid production and glycerin consumption under photoheterotrophic conditions based on logistic, Luedeking–Piret and Luedeking–Piret-like equations. All experiments were conducted in a 2 L batch reactor without considering CO2 effect on algae’s growth and lipid production. Biomass and lipid production increased with glycerin as carbon source and were well described by the logistic and Luedeking–Piret equations respectively. Model predictions were in satisfactory agreement with measured data and the mode of lipid production was growth-associated. Sensitivity analysis was applied to examine the effects of certain important parameters on model performance. Results showed that S0, the initial concentration of glycerin, was the most significant factor for algae growth and lipid production. This model is applicable for prediction of other single cell algal species but model testing is recommended before scaling up the fermentation of process. PMID:21115343

  11. Dissolution of Fe(III)(hydr)oxides by an Aerobic Bacterium

    SciTech Connect

    Maurice, P.

    2004-12-13

    This project investigated the effects of an aerobic Pseudomonas mendocina bacterium on the dissolution of Fe(III)(hydr)oxides. The research is important because metals and radionuclides that adsorb to Fe(III)(hydr)oxides could potentially be remobilized by dissolving bacteria. We showed that P. mendocina is capable of dissolving Fe-bearing minerals by a variety of mechanisms, including production of siderophores, pH changes, and formation of reductants. The production of siderophores by P. mendocina was quantified under a variety of growth conditions. Finally, we demonstrated that microbial siderophores may adsorb to and enhance dissolution of clay minerals.

  12. Thermal and solutal conditions at the tips of a directional dendritic growth front

    NASA Technical Reports Server (NTRS)

    Mccay, T. D.; Mccay, Mary H.; Hopkins, John A.

    1991-01-01

    The line-of-sight averaged, time-dependent dendrite tip concentrations for the diffusion dominated vertical directional solidification of a metal model (ammonium chloride and water) were obtained by extrapolating exponentially fit diffusion layer profiles measured using a laser interferometer. The tip concentrations were shown to increase linearly with time throughout the diffusion dominated growth process for an initially stagnant dendritic array. The process was terminated for the cases chosen by convective breakdown suffered when the conditionally stable diffusion layer exceeded the critical Rayleigh criteria. The transient tip concentrations were determined to significantly exceed the values predicted for steady state, thus producing much larger constitutional undercoolings. This has ramifications for growth speeds, arm spacings and the dendritic structure itself.

  13. Residual Gases in Crystal Growth Systems: Their Origin, Magnitude, and Dependence on the Processing Conditions

    NASA Technical Reports Server (NTRS)

    Palosz, W.

    2003-01-01

    Residual gases present in closed ampoules may affect different crystal growth processes. Their presence may affect techniques requiring low pressures and affect the crystal quality in different ways. For that reason a good understanding and control of formation of residual gases may be important for an optimum design and meaningful interpretation of crystal growth experiments. Our extensive experimental and theoretical study includes degassing of silica glass and generation of gases from various source materials. Different materials processing conditions, like outgassing under vacuum, annealing in hydrogen, resublimation, different material preparation procedures, multiple annealings, different processing times, and others were applied and their effect on the amount and composition of gas were analyzed. The experimental results were interpreted based on theoretical calculations on diffusion in silica glass and source materials and thermochemistry of the system. Procedures for a reduction of the amount of gas are also discussed.

  14. Crystal Growth of Hen Egg-White Lysozyme (HEWL) under Various Gravity Conditions

    NASA Astrophysics Data System (ADS)

    Pan, Weichun; Xu, Jin; Tsukamoto, Katsuo; Koizumi, Masako; Yamazaki, Tomoya; Zhou, Ru; Li, Ang; Fu, Yuying

    2013-08-01

    Motivated by the enhancement of protein quality under microgravity condition, the behaviors of crystal growth under various gravity conditions have been monitored via Foton Satellite and parabolic flight. We found that the normal growth rate and the step velocity would be enhanced only at high protein concentration. Although the difference of diffusion between monomer lysozyme molecule and main impurity species in HWEL dimer may be able to explain this enhancement in long period at high protein concentration, it is not valid at low lysozyme concentration and it can't explain the results obtained by parabolic flight, in which microgravity condition maintained only about 20 s. In order to compromise this contradiction, cluster, universal existing in protein solution, has been picked up. The dynamic light scattering technique figured out dimer is served as the seed for cluster formation. Due to its large size, cluster keeps still under microgravity. Via this mechanism, the purification of lysozyme above crystal surface has been achieved. We also found the two supergravity (˜1.5 g) periods immediately before and after microgravity period have different effects on the step velocity. The pre-MG period depresses the step velocity while the post-MG enhances it. This odd phenomenon ascribes to two factors: (1) the flow rate modification and (2) the purity of protein solution immediate above crystal surface.

  15. Optimizing pentacene thin-film transistor performance: Temperature and surface condition induced layer growth modification

    PubMed Central

    Lassnig, R.; Hollerer, M.; Striedinger, B.; Fian, A.; Stadlober, B.; Winkler, A.

    2015-01-01

    In this work we present in situ electrical and surface analytical, as well as ex situ atomic force microscopy (AFM) studies on temperature and surface condition induced pentacene layer growth modifications, leading to the selection of optimized deposition conditions and entailing performance improvements. We prepared p++-silicon/silicon dioxide bottom-gate, gold bottom-contact transistor samples and evaluated the pentacene layer growth for three different surface conditions (sputtered, sputtered + carbon and unsputtered + carbon) at sample temperatures during deposition of 200 K, 300 K and 350 K. The AFM investigations focused on the gold contacts, the silicon dioxide channel region and the highly critical transition area. Evaluations of coverage dependent saturation mobilities, threshold voltages and corresponding AFM analysis were able to confirm that the first 3–4 full monolayers contribute to the majority of charge transport within the channel region. At high temperatures and on sputtered surfaces uniform layer formation in the contact–channel transition area is limited by dewetting, leading to the formation of trenches and the partial development of double layer islands within the channel region instead of full wetting layers. By combining the advantages of an initial high temperature deposition (well-ordered islands in the channel) and a subsequent low temperature deposition (continuous film formation for low contact resistance) we were able to prepare very thin (8 ML) pentacene transistors of comparably high mobility. PMID:26543442

  16. Growth conditions, elemental accumulation and induced physiological changes in Chinese cabbage.

    PubMed

    Moreno, Diego A; Víllora, Gemma; Ruiz, Juan M; Romero, Luis

    2003-08-01

    Soils contaminated with low levels of heavy metals and other trace elements are now frequently used for vegetable growing. In this situation, heavy metals and trace elements from these polluted soils may accumulate in the agricultural plants being grown in them and thereby enter the human food chain. The objectives of this study are to elucidate the effects of growth conditions, manipulated by the crop covers, on the phytoaccumulation of elements, and to investigate the conceivable influences of these conditions on the plant biochemistry. In three consecutive years of field experiments, open air (T(0)), and floating rowcover treatments (T(1): perforated polyethylene 50 micrometers; T(2): polypropylene 17 gm(-2)) were used to produce different environmental conditions for the growth of Chinese cabbage [Brassica rapa L. (Pekinensis group) cv. 'Nagaoka 50']. Five samplings (whole tops) were carried out from transplanting to harvest and measurements of B, Al, Ag, Si and Ca concentration as well as phenolics (orto-diphenols, total phenols and anthocyanins), pectic fractions, amino acids (histidine, phenylalanine and tyrosine) and polyphenol oxidase activity, were carried out in samples. The T(1) (perforated polyethylene sheet) gave greater B, Al, Ag and Si concentration and phytoextraction (in weight units) than the open-air control. These findings can help to develop new cost-effective techniques for phytoremediation as the application of plastic covers in the field. The build-up of heavy metals in those crops would make the product less suitable for human consumption. PMID:12781236

  17. Human conditions of insulin-like growth factor-I (IGF-I) deficiency

    PubMed Central

    2012-01-01

    Insulin-like growth factor I (IGF-I) is a polypeptide hormone produced mainly by the liver in response to the endocrine GH stimulus, but it is also secreted by multiple tissues for autocrine/paracrine purposes. IGF-I is partly responsible for systemic GH activities although it possesses a wide number of own properties (anabolic, antioxidant, anti-inflammatory and cytoprotective actions). IGF-I is a closely regulated hormone. Consequently, its logical therapeutical applications seems to be limited to restore physiological circulating levels in order to recover the clinical consequences of IGF-I deficiency, conditions where, despite continuous discrepancies, IGF-I treatment has never been related to oncogenesis. Currently the best characterized conditions of IGF-I deficiency are Laron Syndrome, in children; liver cirrhosis, in adults; aging including age-related-cardiovascular and neurological diseases; and more recently, intrauterine growth restriction. The aim of this review is to summarize the increasing list of roles of IGF-I, both in physiological and pathological conditions, underlying that its potential therapeutical options seem to be limited to those proven states of local or systemic IGF-I deficiency as a replacement treatment, rather than increasing its level upper the normal range. PMID:23148873

  18. Growth conditions of 0-group plaice Pleuronectes platessa in the western Wadden Sea as revealed by otolith microstructure analysis

    NASA Astrophysics Data System (ADS)

    Cardoso, Joana F. M. F.; Freitas, Vânia; de Paoli, Hélène; Witte, Johannes IJ.; van der Veer, Henk W.

    2016-05-01

    Growth studies based on population-based growth estimates are limited by the fact that they do not take into account differences in age/size structure within the population. To overcome these problems, otolith microstructure analysis is often used to estimate individual growth. Here, we analyse growth of 0-group plaice in the western Wadden Sea in two years: a year preceded by a mild winter (1995) and a year preceded by a severe winter (1996). Growth was analysed by combining information on individual growth based on otolith analysis with predictions of maximum growth (= under optimal food conditions) based on a Dynamic Energy Budget model. Otolith analysis revealed that settlement occurred earlier in 1995 than in 1996. In both years, one main cohort was found, followed by a group of late settlers. No differences in mean length-at-age were found between these groups. DEB modelling suggested that growth was not maximal during the whole growing season: realized growth (the fraction of maximum growth realized by 0-group plaice) declined in the summer, although this decline was relatively small. In addition, late settling individuals exhibited lower realized growth than individuals from the main cohort. This study confirms that growth conditions for 0-group plaice are not optimal and that a growth reduction occurs in summer, as suggested in previous studies.

  19. OPTIMAL GROWTH CONDITIONS AND ANTIOXIDATIVE ACTIVITIES OF CYLINDROTHECA CLOSTERIUM (BACILLARIOPHYCEAE)(1).

    PubMed

    Affan, Abu; Heo, Soo-Jin; Jeon, You-Jin; Lee, Joon-Baek

    2009-12-01

    We isolated the unialgal strain of Cylindotheca closterium (Ehrenb.) Reimann et J. C. Lewin and produced an axenic strain using an antibiotic cocktail of enriched f/2 artificial seawater medium. The optimal growth conditions were estimated under 27 different combinations of temperature, salinity, and nutrients, and mass culture was performed based on the best specific growth conditions. Its antioxidant activities were determined from the extracts of methanol, water, and enzymes (proteases and carbohydrases). The maximum specific growth rate (μmax ) varied from 0.63 to 0.97 · d(-1) . The maximum cell density was 7.20 × 10(4) cells · mL(-1) , while the μmax was 0.82 · d(-1) in culture conditions of 20°C, 30 psu (practical salinity unit), and "F" nutrient concentrations on day 10 of the culture period. The scavenging rates for 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical were 72.5% and 69.4% from Viscozyme and methanol extracts, respectively. The enzymatic extracts of C. closterium prepared by the hydrolyses of Amyloglucosidase (AMG) and Viscozyme showed 45.8% and 45.5% nitric-oxide-scavenging rates, slightly lower than the activity of alpha-tocopherol (α-tocopherol) but similar to butylated hydroxytoluene (BHT). The extract from methanol and water showed 44.8% and 44.4% scavenging rates, statistically similar with BHT. The metal-chelating activities of the Kojizyme, Alcalase, methanol, Viscozyme, and Neutrase extracts were 67.1, 53.9, 53.2, 52.1, and 50.2 %, respectively, five to six times higher than the commercial antioxidants. The AMG, Viscozyme, and Neutrase extracts showed a remarkable linoleic acid peroxidation inhibition, which was higher than BHT and statistically similar with α-tocopherol. PMID:27032598

  20. Enhancement of Nitrate Uptake and Growth of Barley Seedlings by Calcium under Saline Conditions 1

    PubMed Central

    Ward, Michael R.; Aslam, Muhammad; Huffaker, Ray C.

    1986-01-01

    The effect of Ca2+ on NO3− assimilation in young barley (Hordeum vulgare L. var CM 72) seedlings in the presence and absence of NaCl was studied. Calcium increased the activity of the NO3− transporter under saline conditions, but had little effect under nonsaline conditions. Calcium decreased the induction period for the NO3− transporter under both saline and nonsaline conditions but had little effect on its apparent Km for NO3− both in the presence and absence of NaCl. The enhancement of NO3− transport by Ca2+ under saline conditions was dependent on the presence of Ca2+ in the uptake solution along with the salt, since Ca2+ had no effect when supplied before or after salinity stress. Although Mn2+ and Mg2+ enhanced NO3− uptake under saline conditions, neither was as effective as Ca2+. In longer studies, increasing the Ca2+ concentration in saline nutrient solutions resulted in increases in NO3− assimilation and seedling growth. PMID:11539765

  1. Enhancement of nitrate uptake and growth of barley seedlings by calcium under saline conditions

    NASA Technical Reports Server (NTRS)

    Ward, M. R.; Aslam, M.; Huffaker, R. C.

    1986-01-01

    The effect of Ca2+ on NO3- assimilation in young barley (Hordeum vulgare L. var CM 72) seedlings in the presence and absence of NaCl was studied. Calcium increased the activity of the NO3- transporter under saline conditions, but had little effect under nonsaline conditions. Calcium decreased the induction period for the NO3- transporter under both saline and nonsaline conditions but had little effect on its apparent Km for NO3- both in the presence and absence of NaCl. The enhancement of NO3- transport by Ca2+ under saline conditions was dependent on the presence of Ca2+ in the uptake solution along with the salt, since Ca2+ had no effect when supplied before or after salinity stress. Although Mn2+ and Mg2+ enhanced NO3- uptake under saline conditions, neither was as effective as Ca2+. In longer studies, increasing the Ca2+ concentration in saline nutrient solutions resulted in increases in NO3- assimilation and seedling growth.

  2. Influence of culture conditions on mycelial growth and bioluminescence of Gerronema viridilucens.

    PubMed

    Mendes, Luiz F; Bastos, Erick L; Desjardin, Dennis E; Stevani, Cassius V

    2008-05-01

    Herein we describe a procedure for measuring the total light emission of the naturally bioluminescent tropical fungus Gerronema viridilucens and the optimization of culture conditions using multivariate factorial anova. Cultures growing on an agar surface in 35 mm Petri dishes at 90% humidity show optimal bioluminescence emission at 25 degrees C in the presence of 1.0% sugar cane molasses, 0.10% yeast extract and pH 6.0 (nonbuffered). Temperature and pH are the most important factors for both mycelial growth and bioluminescence. PMID:18355288

  3. Features of Scots pine radial growth in conditions of provenance trial.

    NASA Astrophysics Data System (ADS)

    Kuzmin, Sergey; Kuzmina, Nina

    2013-04-01

    Provenance trial of Scots pine in Boguchany forestry of Krasnoyarsk krai is conducted on two different soils - dark-grey loam forest soil and sod-podzol sandy soil. Complex of negative factors for plant growth and development appears in dry conditions of sandy soil. It could results in decrease of resistance to diseases. Sandy soils in different climatic zones have such common traits as low absorbing capacity, poorness of elemental nutrition, low microbiological activity and moisture capacity, very high water permeability. But Scots pine trees growing in such conditions could have certain advantages and perspectives of use. In the scope of climate change (global warming) the study of Scots pine growth on sandy soil become urgent because of more frequent appearance of dry seasons. Purpose of the work is revelation of radial growth features of Scots pine with different origin in dry conditions of sandy soil and assessment of external factors influence. The main feature of radial growth of majority of studied pine provenances in conditions of sandy soil is presence of significant variation of increment with distinct decline in 25-years old with loss of tree rings in a number of cases. The reason of it is complex of factors: deficit of June precipitation and next following outbreak of fungal disease. Found «frost rings» for all trees of studied clymatypes in 1992 are the consequence of temperature decline from May 21 to June 2 - from 23 down to 2 degree Celsius. Perspective climatypes with biggest radial increments and least sensitivity to fungal disease were revealed. Eniseysk and Vikhorevka (from Krasnoyarsk krai and Irkutsk oblast)provenances of pine have the biggest radial increments, the least sensitivity to Cenangium dieback and smallest increments decline. These climatypes are in the group of perspective provenances and in present time they are recommended for wide trial in the region for future use in plantation forest growing. Kandalaksha (Murmansk oblast

  4. In-Situ Monitoring of Particle Growth at PEMFC Cathode under Accelerated Cycling Conditions

    SciTech Connect

    Redmond, Erin L.; Setzler, Brian P.; Juhas, Pavol; Billinge, Simon J.L.; Fuller, Thomas F.

    2012-10-25

    An in-situ method to measure changes in catalyst particle size at the cathode of a proton exchange membrane fuel cell is demonstrated. Synchrotron X-rays, 58 keV, were used to measure the pair distribution function on an operating fuel cell and observe the growth of catalyst particles under accelerated degradation conditions. The stability of Pt/C and PtCo/C with different initial particle sizes was monitored over 3000 potential cycles. The increase in particle size was fit to a linear trend as a function of cycles. The most stable electrocatalyst was found to be the alloyed PtCo with the larger initial particle size.

  5. Enhanced selection of micro-aerobic pentachlorophenol degrading granular sludge.

    PubMed

    Lv, Yuancai; Chen, Yuancai; Song, Wenzhe; Hu, Yongyou

    2014-09-15

    Column-type combined reactors were designed to cultivate micro-aerobic pentachlorophenol (PCP) degrading granular sludge under oxygen-limited conditions (0.1-0.2 mgL(-1)) over 39-day experimental period. Micro-aerobic granular had both anaerobic activity (SMA: 2.34 mMCH4/hg VSS) and aerobic activity (SOUR: 2.21 mMO2/hg VSS). Metabolite analysis results revealed that PCP was sequentially dechlorinated to TCP, DCP, and eventually to MCP. Methanogens were not directly involved in the dechlorination of PCP, but might played a vital role in stabilizing the overall structure of the granule sludge. For Eubacteria, the Shannon Index (2.09 in inoculated granular sludge) increased both in micro-aerobic granular sludge (2.61) and PCP-degradation granular sludge (2.55). However, for Archaea, it decreased from 2.53 to 1.85 and 1.84, respectively. Although the Shannon Index demonstrated slight difference between micro-aerobic granular sludge and PCP-degradation granular sludge, the Principal Component Analysis (PCA) indicated obvious variance of the microbial composition, revealing significant effect of micro-aerobic condition and PCP on microbial community. Furthermore, nucleotide sequencing indicated that the main microorganisms for PCP degradation might be related to Actinobacterium and Sphingomonas. These results provided insights into situ bioremediation of environments contaminated by PCP and had practical implications for the strategies of PCP degradation. PMID:25151236

  6. Interactive effects of hypobaria, low temperature, and CO 2 atmospheres inhibit the growth of mesophilic Bacillus spp. under simulated martian conditions

    NASA Astrophysics Data System (ADS)

    Schuerger, Andrew C.; Nicholson, Wayne L.

    2006-11-01

    Robotic spacecraft are launched with finite levels of terrestrial microorganisms that are similar to the microbial communities within facilities in which spacecraft are assembled. In particular, spores of mesophilic aerobic Bacillus species are common spacecraft contaminants considered most likely to survive interplanetary transfer to Mars. During the cruise phase to Mars, and then again during surface operations, microbial bioloads are exposed to a diversity of biocidal factors that are likely to render the microbial species either dead or significantly inhibited from active metabolic activity and replication. We report here, for the first time, that interactive effects of low pressure, low temperature, and high CO 2 atmospheres approaching conditions likely to be encountered on the martian surface strongly inhibit the growth and replication of seven common Bacillus spp. isolated from spacecraft. Tests were conducted within a small glass bell-jar system maintained in a low-temperature microbial incubator. Atmospheric pressures were controlled at 1013 (Earth-normal), 100, 50, 35, 25, or 15 mb, and temperatures were maintained at 30, 20, 15, 10, or 5 °C. Experiments were carried out for 48 h or 7 days under either Earth-normal O 2/N 2 or pure CO 2 atmospheres. Results indicated that low pressure, low temperature, and high CO 2 atmospheres, applied separately or in combination, were capable of inhibiting the growth and replication of B. pumilus SAFR-032, B. pumilus FO-36B, B. subtilis HA-101, B. subtilis 42HS-1, B. megaterium KL-197, B. licheniformis KL-196, and B. nealsonii FO-092 under simulated martian conditions. Endospores of all seven Bacillus spp. strains failed to germinate and grow at 25 mb at 30 °C. Although, vegetative cells of these strains exhibited a slightly greater ability to replicate at lower pressures than did endospores, vegetative cells of these species failed to grow at pressures below 25 mb. Interactive effects of these environmental

  7. Improved RDX detoxification with starch addition using a novel nitrogen-fixing aerobic microbial consortium from soil contaminated with explosives.

    PubMed

    Khan, Muhammad Imran; Yang, Jihoon; Yoo, Byungun; Park, Joonhong

    2015-04-28

    In this work, we developed and characterized a novel nitrogen-fixing aerobic microbial consortium for the complete detoxification of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). Aerobic RDX biodegradation coupled with microbial growth and nitrogen fixation activity were effectively stimulated by the co-addition of starch and RDX under nitrogen limiting conditions. In the starch-stimulated nitrogen-fixing RDX degradative consortium, the RDX degradation activity was correlated with the xplA and nifH gene copy numbers, suggesting the involvement of nitrogen fixing populations in RDX biodegradation. Formate, nitrite, nitrate, and ammonia were detected as aerobic RDX degradation intermediates without the accumulation of any nitroso-derivatives or NDAB (4-nitro-2,4-diazabutanal), indicating nearly complete mineralization. Pyrosequencing targeting the bacterial 16S rRNA genes revealed that the Rhizobium, Rhizobacter and Terrimonas population increased as the RDX degradation activity increased, suggesting their involvement in the degradation process. These findings imply that the nitrogen-fixing aerobic RDX degrading consortium is a valuable microbial resource for improving the detoxification of RDX-contaminated soil or groundwater, especially when combined with rhizoremediation. PMID:25661171

  8. Volatile organic compounds associated with microbial growth in automobile air conditioning systems.

    PubMed

    Rose, L J; Simmons, R B; Crow, S A; Ahearn, D G

    2000-09-01

    Volatile organic compounds from Penicillium viridicatum and Methylobacterium mesophilicum growing on laboratory media and on component materials of automobile air conditioners were analyzed with gas chromatography and mass spectrometry. P. viridicatum produced compounds such as 4-methyl thiazole, terpenes and alcohols, whereas M. mesophilicum produced dimethyl disulfide, dimethyl trisulfide, and chlorophenol with growth on laboratory media. In comparison with laboratory media, fewer volatiles were detected from colonized foam insulation materials. Biofilms of M. mesophilicum on aluminum evaporator components produced mainly dimethyl disulfide. These biofilms, after inoculation with P. viridicatum, produced offensive smelling alcohols and esters such as 2-methyl propanol, 3-penten-2-ol, and the ethyl ester of butanoic acid. The moisture and substrates innate to the automobile air conditioning systems provided an environment suitable for microbial biofilm development and odor production. Reduction of retained moisture in the air conditioning system coupled with use of less susceptible or antimicrobial substrates are advised for remediation of the noxious odors. PMID:10915209

  9. Variation of the folding and dynamics of the Escherichia coli chromosome with growth conditions

    PubMed Central

    Yazdi, Nastaran Hadizadeh; Guet, Calin C.; Johnson, Reid C.; Marko, John F.

    2012-01-01

    Summary We examine whether the E. coli chromosome is folded into a self-adherent nucleoprotein complex, or alternately is a confined but otherwise unconstrained self-avoiding polymer. We address this through in vivo visualization, using an inducible GFP fusion to the nucleoid-associated protein Fis to non-specifically decorate the entire chromosome. For a range of different growth conditions, the chromosome is a compact structure that does not fill the volume of the cell, and which moves from the new pole to the cell center. During rapid growth, chromosome segregation occurs well before cell division, with daughter chromosomes coupled by a thin inter-daughter filament before complete segregation, whereas during slow growth chromosomes stay adjacent until cell division occurs. Image correlation analysis indicates that sub-nucleoid structure is stable on a one-minute timescale, comparable to the time scale for redistribution time measured for GFP-Fis after photobleaching. Optical deconvolution and writhe calculation analysis indicate that the nucleoid has a large-scale coiled organization rather than being an amorphous mass. Our observations are consistent with the chromosome having a self-adherent filament organization. PMID:23078205

  10. Refining the alkenone-pCO2 method: The role of algal growth conditions

    NASA Astrophysics Data System (ADS)

    Pearson, A.; Zhang, Y.; Huybers, P. J.; Pagani, M.

    2015-12-01

    The alkenone-pCO2 method based on carbon isotope fractionation during growth of haptophyte algae is one of the most widely used approaches to reconstruct atmospheric CO2 level in the Cenozoic. Based on the fractionation of stable carbon isotopes between dissolved CO2 and phytoplankton biomass, as represented by alkenone lipid biomarkers, this relationship (known as ɛp37:2) scales inversely with growth rate and cell volume to surface area ratio, and positively with CO2. Recently-published estimates for late Pleistocene CO2 levels, however, are poorly correlated with ice core CO2 records, suggesting that alkenone paleobarometry needs to be refined. Here we compiled published records over recent glacial-interglcial (G-IG) cycles and revised the relationship between algal growth rate, as expressed by the physiological parameter 'b', and dissolved phosphate concentration. We further show that the magnitude of change in ɛp37:2 over glacial-interglacial cycles at different sites is dependent on local nutrient conditions, highlighting the importance of constraining b for accurate CO2 estimates. The correlation between GDGT-2/3 ratio and back-calculated b at Ceara Rise (ODP Site 925) suggests that archaeal lipids could be used as proxies to calibrate b. Application of our variable-b method to reported data yields pCO2 estimates that are similar in both trends and magnitude to ice core-derived records.

  11. Role of ammonia-oxidizing bacteria in micropollutant removal from wastewater with aerobic granular sludge.

    PubMed

    Margot, Jonas; Lochmatter, Samuel; Barry, D A; Holliger, Christof

    2016-01-01

    Nitrifying wastewater treatment plants (WWTPs) are more efficient than non-nitrifying WWTPs to remove several micropollutants such as pharmaceuticals and pesticides. This may be related to the activity of nitrifying organisms, such as ammonia-oxidizing bacteria (AOBs), which could possibly co-metabolically oxidize micropollutants with their ammonia monooxygenase (AMO). The role of AOBs in micropollutant removal was investigated with aerobic granular sludge (AGS), a promising technology for municipal WWTPs. Two identical laboratory-scale AGS sequencing batch reactors (AGS-SBRs) were operated with or without nitrification (inhibition of AMOs) to assess their potential for micropollutant removal. Of the 36 micropollutants studied at 1 μg l(-1) in synthetic wastewater, nine were over 80% removed, but 17 were eliminated by less than 20%. Five substances (bisphenol A, naproxen, irgarol, terbutryn and iohexol) were removed better in the reactor with nitrification, probably due to co-oxidation catalysed by AMOs. However, for the removal of all other micropollutants, AOBs did not seem to play a significant role. Many compounds were better removed in aerobic condition, suggesting that aerobic heterotrophic organisms were involved in the degradation. As the AGS-SBRs did not favour the growth of such organisms, their potential for micropollutant removal appeared to be lower than that of conventional nitrifying WWTPs. PMID:26877039

  12. Aerobic Microbial Degradation of Glucoisosaccharinic Acid

    PubMed Central

    Strand, S. E.; Dykes, J.; Chiang, V.

    1984-01-01

    α-Glucoisosaccharinic acid (GISA), a major by-product of kraft paper manufacture, was synthesized from lactose and used as the carbon source for microbial media. Ten strains of aerobic bacteria capable of growth on GISA were isolated from kraft pulp mill environments. The highest growth yields were obtained with Ancylobacter spp. at pH 7.2 to 9.5. GISA was completely degraded by cultures of an Ancylobacter isolate. Ancylobacter cell suspensions consumed oxygen and produced carbon dioxide in response to GISA addition. A total of 22 laboratory strains of bacteria were tested, and none was capable of growth on GISA. GISA-degrading isolates were not found in forest soils. Images PMID:16346467

  13. Effect of cloud microphysics on particle growth under mixed phase conditions

    NASA Astrophysics Data System (ADS)

    Pfitzenmaier, Lukas; Dufournet, Yann; Unal, Christine; Russchenberg, Herman; Myagkov, Alexander; Seifert, Patric

    2015-04-01

    Mixed phase clouds contain both ice particles and super-cooled cloud water droplets in the same volume of air. Currently, one of the main challenges is to observe and understand how ice particles grow by interacting with liquid water within the mixed-phase clouds. In the mid latitudes this process is one of the most efficient processes for precipitation formation. It is particularly important to understand under which conditions growth processes are most efficient within such clouds. The observation of microphysical cloud properties from the ground is one possible approach to study the liquid-ice interaction that play a role on the ice crystal growth processes. The study presented here is based on a ground-based multi-sensor technique. Dataset of this study was taken during the ACCEPT campaign (Analysis of the Composition of mixed-phase Clouds with Extended Polarization Techniques) at Cabauw The Netherlands, autumn 2014. Measurements with the Transportable Atmospheric RAdar (TARA), S-band precipitation radar profiler, from the Delft Technical University, and Ka-band cloud radar systems were performed in cooperation with the Leibniz Institute for Tropospheric Research (TROPOS), Leipzig, Germany. All the radar systems had full Doppler capabilities. In addition , TARA and one of the Ka-band radar systems had full polarimetric capabilities as well, in order to get information of the ice phase within mixed-phase cloud systems. Lidar, microwave radiometer and radiosonde measurements were combined to describe the liquid phase within such clouds. So a whole characterisation of microphysical processes within mixed-phase cloud systems could be done. This study shows how such a combination of instruments is used to: - Detect the liquid layer within the ice clouds - Describe the microphysical conditions for ice particle growth within mixed phase clouds based on cloud hydrometeor shape, size, number concentration obtained from measurements The project aims to observe

  14. The kinetics of dolomite reaction rim growth under isostatic and non-isostatic pressure conditions

    NASA Astrophysics Data System (ADS)

    Helpa, V.; Rybacki, E.; Morales, L. G.; Abart, R.; Dresen, G. H.

    2013-12-01

    During burial and exhumation, rocks are simultaneously exposed to metamorphic reactions and tectonic stresses. Therefore, the reaction rate of newly formed minerals may depend on chemical and mechanical driving forces. Here, we investigate the reaction kinetics of dolomite (CaMg[CO3]2) rim growth by solid-state reactions experiments on oriented calcite (CaCO3) and magnesite (MgCO3) single crystals under isostatic and non-isostatic pressure conditions. Cylindrical samples of 3-5 mm length and 7 mm diameter were drilled and polished perpendicular to the rhombohedral cleavage planes of natural clear crystals. The tests were performed using a Paterson-type deformation apparatus at P = 400 MPa confining pressure, temperatures, T, between 750 and 850°C, and reaction durations, t, of 2 - 146 h to calculate the kinetic parameters of dolomite rim growth under isostatic stress conditions. For non-isostatic reaction experiments we applied in addition differential stresses, σ, up to 40 MPa perpendicular to the contact interface at T = 750°C for 4 - 171 h duration, initiating minor inelastic deformation of calcite. The thickness of the resulting dolomite reaction rims increases linearly with the square root of time, indicating a diffusion-controlled reaction. The rims consist of two different textural domains. Granular dolomite grains (≈ 2 -5 μm grain size) form next to calcite and elongated palisade-shaped grains (1-6 μm diameter) grow perpendicular to the magnesite interface. Texture measurements with the electron backscatter diffraction technique indicate that the orientations of dolomite grains are mainly influenced by the orientation of the calcite educt crystal, in particular in the granular rim. To some extent, the texture of dolomite palisades is also influenced by the orientation of magnesite. The thickness of the two individual layers increases with temperature. At 400 MPa isostatic pressure, T = 750°C and t = 29 hours, a 5 μm thick granular dolomite layer

  15. Proposal of a Simple Plant Growth System under Microgravity Conditions in Space

    NASA Astrophysics Data System (ADS)

    Hirai, Hiroaki; Kitaya, Yoshiaki; Hirai, Takehiro; Tsukamoto, Koya; Yamashita, Youichirou

    2012-07-01

    Plant culture in space has multiple functions for human life support such as providing food and purifying air and water. It is also suggested that crew can relieve their stress by watching growing plants and by enjoying fresh vegetable food during staying for several months in the International Space Station. Under such circumstances, it is an utmost importance to develop plant culture equipment that can be handled more easily by crew. This study aims to develop an easy-to-use plant growth system with modification of commercial household plant culture equipment. The item is equipped with a peltier device for cooling air and collecting water vapor in the growth room. The study was conducted to examine the performance of the equipment under microgravity conditions that were created by the parabolic airplane flights. As a result, the temperature of the peltier device was affected under the microgravity conditions due to the absence of heat convection. When an air flow was made with an air circulation fan, the temperature of the peltier device was stable to gravity changes. The water recycling method for an automatic nutrient solution supply system in the closed plant culture equipment under microgravity is proposed. In addition, a high output white LEDs showing a good performance for growing leafy vegetables will be introduced.

  16. Plasticity of Streptomyces coelicolor Membrane Composition Under Different Growth Conditions and During Development

    PubMed Central

    Sandoval-Calderón, Mario; Nguyen, Don D.; Kapono, Clifford A.; Herron, Paul; Dorrestein, Pieter C.; Sohlenkamp, Christian

    2015-01-01

    Streptomyces coelicolor is a model actinomycete that is well known for the diversity of its secondary metabolism and its complex life cycle. As a soil inhabitant, it is exposed to heterogeneous and frequently changing environmental circumstances. In the present work, we studied the effect of diverse growth conditions and phosphate depletion on its lipid profile and the relationship between membrane lipid composition and development in S. coelicolor. The lipid profile from cultures grown on solid media, which is closer to the natural habitat of this microorganism, does not resemble the previously reported lipid composition from liquid grown cultures of S. coelicolor. Wide variations were also observed across different media, growth phases, and developmental stages indicating active membrane remodeling. Ornithine lipids (OL) are phosphorus-free polar lipids that were accumulated mainly during sporulation stages, but were also major components of the membrane under phosphorus limitation. In contrast, phosphatidylethanolamine, which had been reported as one of the major polar lipids in the genus Streptomyces, is almost absent under these conditions. We identified one of the genes responsible for the synthesis of OL (SCO0921) and found that its inactivation causes the absence of OL, precocious morphological development and actinorhodin production. Our observations indicate a remarkable plasticity of the membrane composition in this bacterial species, reveal a higher metabolic complexity than expected, and suggest a relationship between cytoplasmic membrane components and the differentiation programs in S. coelicolor. PMID:26733994

  17. Evaluation of experiments involving the study of plant orientation and growth under different gravitational conditions.

    PubMed

    Merkys, A J; Laurinavicius, R S; Svegzdiene, D V; Rakleviciene, D P; Jarosius, A V; Rupainiene, O J

    1989-01-01

    The manifestation of gravitropic reaction in plants has been considered from the phylogenetic point of view. A chart has been suggested according to which it is supposed that the first indications of the ability to identify the direction of the gravitational vector were inherent in the most ancient eukaryotes, which gave rise to green, brown, yellow-green, golden and diatomaceous algae as well as fungi. The experiments on the role of gravity in plant ontogenesis are being continued. The sum total of the data obtained in a number of experiments in space shows that under these conditions a structurally modified but normally functioning gravireceptive apparatus is formed. The data confirming the modification, under changed gravity, of the processes of integral and cellullar growth of the axial organs of seedlings as well as of the anatomo-morphological structure and developmental rates of plants during their prolonged growth in space are presented. It is assumed that this fact testifies to the presence of systems interacting with gravity during plant ontogenesis. At the same time the necessity for further experiments in order to differentiate an immediate biological effect of gravity from the ones conditioned by it indirectly due to the changes in the behavior of liquids and gases is pointed out. The methodological aspects of biological experiments in space as the main source of reliable information on the biological role of gravity are discussed. PMID:11537336

  18. Growth condition study of algae function in ecosystem for CO2 bio-fixation.

    PubMed

    Tsai, David Dah-Wei; Ramaraj, Rameshprabu; Chen, Paris Honglay

    2012-02-01

    Algae niche play a crucial role on carbon cycle and have great potential for CO(2) sequestration. This study was to investigate the CO(2) bio-fixation by the high rate pond (HRP) to mimic the algae function of nature. All the reactors can keep CO(2) consumption efficiencies over 100%. The statistical analyses proved HRPs were close to the natural system from all the growth conditions. The HRP could show the "natural optimization as nature" to perform as well as the artificial reactor of continuously stirred tank reactor (CSTR). In the nutrition study, the carbon mass balance indicated CO(2) was the main carbon source. Accordingly, the HRPs can keep a neutral pH range to provide dissolved oxygen (DO), to promote total nitrogen (TN)/total phosphorous (TP) removal efficiencies and to demonstrate self-purification process. Furthermore, the observations of different nitrogen species in the reactors demonstrated that the major nitrogen source was decided by pH. This finding logically explained the complex nitrogen uptake by algae in nature. Consequently, this study took advantage of HRP to explore the processes of efficient CO(2) uptake with the corresponding growth condition in the ecosystem. Those results contributed the further understanding of the role of CO(2) bio-fixation in nature and demonstrated HRP could be a potential ecological engineering alternative. PMID:22196805

  19. Influence of Growth Conditions on Magnetite Nanoparticles Electro-Crystallized in the Presence of Organic Molecules

    PubMed Central

    Mosivand, Saba; Monzon, Lorena M. A.; Kazeminezhad, Iraj; Coey, J. Michael D.

    2013-01-01

    Magnetite nanoparticles were synthesized by electrocrystallization in the presence of thiourea or sodium butanoate as an organic stabilizer. The synthesis was performed in a thermostatic electrochemical cell containing two iron electrodes with an aqueous solution of sodium sulfate as electrolyte. The effects of organic concentration, applied potential and growth temperature on particle size, morphology, structure and magnetic properties were investigated. The magnetite nanoparticles were characterized by X-ray diffraction, electron microscopy, magnetometry and Mössbauer spectrometry. When the synthesis is performed in the presence of sodium butanoate at 60 °C, a paramagnetic ferric salt is obtained as a second phase; it is possible to avoid formation of this phase, increase the specific magnetization and improve the structure of the oxide particles by tuning the growth conditions. Room-temperature magnetization values range from 45 to 90 Am2kg−1, depending on the particle size, type of surfactant and synthesis conditions. Mössbauer spectra, which were recorded at 290 K for all the samples, are typical of nonstoichiometric Fe3−δO4, with a small excess of Fe3+, 0.05 ≤ δ ≤ 0.15. PMID:23685871

  20. Nanoparticle growth and surface chemistry changes in cell-conditioned culture medium

    PubMed Central

    Kendall, Michaela; Hodges, Nikolas J.; Whitwell, Harry; Tyrrell, Jess; Cangul, Hakan

    2015-01-01

    When biomolecules attach to engineered nanoparticle (ENP) surfaces, they confer the particles with a new biological identity. Physical format may also radically alter, changing ENP stability and agglomeration state within seconds. In order to measure which biomolecules are associated with early ENP growth, we studied ENPs in conditioned medium from A549 cell culture, using dynamic light scattering (DLS) and linear trap quadrupole electron transfer dissociation mass spectrometry. Two types of 100 nm polystyrene particles (one uncoated and one with an amine functionalized surface) were used to measure the influence of surface type. In identically prepared conditioned medium, agglomeration was visible in all samples after 1 h, but was variable, indicating inter-sample variability in secretion rates and extracellular medium conditions. In samples conditioned for 1 h or more, ENP agglomeration rates varied significantly. Agglomerate size measured by DLS was well correlated with surface sequestered peptide number for uncoated but not for amine coated polystyrene ENPs. Amine-coated ENPs grew much faster and into larger agglomerates associated with fewer sequestered peptides, but including significant sequestered lactose dehydrogenase. We conclude that interference with extracellular peptide balance and oxidoreductase activity via sequestration is worthy of further study, as increased oxidative stress via this new mechanism may be important for cell toxicity. PMID:25533102

  1. Nanoparticle growth and surface chemistry changes in cell-conditioned culture medium.

    PubMed

    Kendall, Michaela; Hodges, Nikolas J; Whitwell, Harry; Tyrrell, Jess; Cangul, Hakan

    2015-02-01

    When biomolecules attach to engineered nanoparticle (ENP) surfaces, they confer the particles with a new biological identity. Physical format may also radically alter, changing ENP stability and agglomeration state within seconds. In order to measure which biomolecules are associated with early ENP growth, we studied ENPs in conditioned medium from A549 cell culture, using dynamic light scattering (DLS) and linear trap quadrupole electron transfer dissociation mass spectrometry. Two types of 100 nm polystyrene particles (one uncoated and one with an amine functionalized surface) were used to measure the influence of surface type. In identically prepared conditioned medium, agglomeration was visible in all samples after 1 h, but was variable, indicating inter-sample variability in secretion rates and extracellular medium conditions. In samples conditioned for 1 h or more, ENP agglomeration rates varied significantly. Agglomerate size measured by DLS was well correlated with surface sequestered peptide number for uncoated but not for amine coated polystyrene ENPs. Amine-coated ENPs grew much faster and into larger agglomerates associated with fewer sequestered peptides, but including significant sequestered lactose dehydrogenase. We conclude that interference with extracellular peptide balance and oxidoreductase activity via sequestration is worthy of further study, as increased oxidative stress via this new mechanism may be important for cell toxicity. PMID:25533102

  2. Is ragweed pollen allergenicity governed by environmental conditions during plant growth and flowering?

    PubMed Central

    Ghiani, Alessandra; Ciappetta, Silvia; Gentili, Rodolfo; Asero, Riccardo; Citterio, Sandra

    2016-01-01

    Pollen allergenicity is one of the main factors influencing the prevalence and/or severity of allergic diseases. However, how genotype and environment contribute to ragweed pollen allergenicity has still to be established. To throw some light on the factors governing allergenicity, in this work 180 ragweed plants from three Regions (Canada, France, Italy) were grown in both controlled (constant) and standard environmental conditions (seasonal changes in temperature, relative humidity and light). Pollen from single plants was characterized for its allergenic potency and for the underlying regulation mechanisms by studying the qualitative and quantitative variations of the main isoforms of the major ragweed allergen Amb a 1. Results showed a statistically higher variability in allergenicity of pollen from standard conditions than from controlled conditions growing plants. This variability was due to differences among single plants, regardless of their origin, and was not ascribed to differences in the expression and IgE reactivity of individual Amb a 1 isoforms but rather to quantitative differences involving all the studied isoforms. It suggests that the allergenic potency of ragweed pollen and thus the severity of ragweed pollinosis mainly depends on environmental conditions during plant growth and flowering, which regulate the total Amb a 1 content. PMID:27457754

  3. QTLs and candidate genes for rice root growth under flooding and upland conditions.

    PubMed

    Zheng, Bing-Song; Yang, Ling; Mao, Chuan-Zao; Zhang, Wei-Ping; Wu, Ping

    2006-02-01

    To investigate the genetic factors underlying constitutive and adaptive root growth under different water-supply conditions, a double haploid (DH) population, derived from a cross between lowland rice variety IR64 and upland rice variety Azucena, with 284 molecular markers was used in cylindrical pot experiments. Several QTLs for seminal root length (SRL), adventitious root number (ARN) and total root dry weight (RW) respectively, under both flooding and upland conditions were detected. Two identical QTLs for SRL and RW were found under flooding and upland conditions. The relative parameters defined as the ratio of parameters under the two water-supply conditions were also used for QTL analysis. A comparative analysis among different genetic populations was performed for the QTLs for root traits and several consistent QTLs for root traits across genetic backgrounds were detected. Candidate genes for cell expansion and elongation were used for comparative mapping with the detected QTLs. Four cell wall-related expressed sequence tags (ESTs) for OsEXP2, OsEXP4, EXT and Xet were mapped on the intervals carrying the QTLs for root traits. PMID:16529298

  4. Is ragweed pollen allergenicity governed by environmental conditions during plant growth and flowering?

    NASA Astrophysics Data System (ADS)

    Ghiani, Alessandra; Ciappetta, Silvia; Gentili, Rodolfo; Asero, Riccardo; Citterio, Sandra

    2016-07-01

    Pollen allergenicity is one of the main factors influencing the prevalence and/or severity of allergic diseases. However, how genotype and environment contribute to ragweed pollen allergenicity has still to be established. To throw some light on the factors governing allergenicity, in this work 180 ragweed plants from three Regions (Canada, France, Italy) were grown in both controlled (constant) and standard environmental conditions (seasonal changes in temperature, relative humidity and light). Pollen from single plants was characterized for its allergenic potency and for the underlying regulation mechanisms by studying the qualitative and quantitative variations of the main isoforms of the major ragweed allergen Amb a 1. Results showed a statistically higher variability in allergenicity of pollen from standard conditions than from controlled conditions growing plants. This variability was due to differences among single plants, regardless of their origin, and was not ascribed to differences in the expression and IgE reactivity of individual Amb a 1 isoforms but rather to quantitative differences involving all the studied isoforms. It suggests that the allergenic potency of ragweed pollen and thus the severity of ragweed pollinosis mainly depends on environmental conditions during plant growth and flowering, which regulate the total Amb a 1 content.

  5. Effects of climatic conditions and soil properties on Cabernet Sauvignon berry growth and anthocyanin profiles.

    PubMed

    Cheng, Guo; He, Yan-Nan; Yue, Tai-Xin; Wang, Jun; Zhang, Zhen-Wen

    2014-01-01

    Climatic conditions and soil type have significant influence on grape ripening and wine quality. The reported study was conducted in two "Cabernet Sauvignon (Vitis vinifera L.V)" vineyards located in Xinjiang, a semiarid wine-producing region of China during two vintages (2011 and 2012). The results indicate that soil and climate affected berry growth and anthocyanin profiles. These two localities were within a distance of 5 km from each other and had soils of different physical and chemical composition. For each vineyard, the differences of anthocyanin concentrations, and parameters concerning berry growth and composition between the two years could be explained by different climatic conditions. Soil effect was studied by investigation of differences in berry composition and anthocyanin profiles between the two vineyards in the same year, which could be explained mainly by the different soil properties, vine water and nitrogen status. Specifically, the soils with less water and organic matter produced looser clusters, heavier berry skins and higher TSS, which contributed to the excellent performance of grapes. Compared with 2011, the increases in anthocyanin concentrations for each vineyard in 2012 could be attributed to smaller number of extreme temperature (>35 °C) days and rainfall, lower vine water status and N level. The explanation for higher anthocyanin concentrations in grape skins from the soils with less water and organic matter could be the vine status differences, lighter berry weight and heavier skin weight at harvest. In particular, grapes from the soils with less water and organic matter had higher levels of 3'5'-substituded, O-methylated and acylated anthocyanins, which represented a positive characteristic conferring more stable pigmentation to the corresponding wine in the future. The present work clarifies the effects of climate and soil on berry growth and anthocyanin profiles, thus providing guidance for production of high-quality wine grapes

  6. Growth of praseodymium oxide on Si(111) under oxygen-deficient conditions

    SciTech Connect

    Schaefer, A.; Zielasek, V.; Baeumer, M.; Schmidt, Th.; Schowalter, M.; Schulz, Ch.; Rosenauer, A.; Falta, J.; Sandell, A.; Seifarth, O.; Schroeder, T.; Wollschlaeger, J.

    2009-07-15

    Surface science studies of thin praseodymium oxide films grown on silicon substrates are of high interest in view of applications in such different fields as microelectronics and heterogeneous catalysis. In particular, a detailed characterization of the growth and the final structure of the films are mandatory to achieve a fundamental understanding of such topics as oxygen mobility and defect structure, and their role for the electronic and chemical properties. In this paper, the MBE growth of praseodymium oxide films on Si(111) substrates was investigated at low-deposition rates (0.06 nm/min) and low-oxygen partial pressures (p(O{sub 2})<1x10{sup -10} mbar). To obtain insight into the structure and chemical composition of the growing film, spot profile analyzing low-energy electron diffraction (SPA-LEED), transmission electron microscopy, and synchrotron radiation-based x-ray photoelectron spectroscopy (XPS) and x-ray absorption spectroscopy (XAS) were applied. SPA-LEED reveals the formation of an initial closed layer followed by continuous roughening and formation of ordered three-dimensional structures. This result is in contrast to observations at higher-deposition rates, were a layer-by-layer growth was reported. XAS and XPS provide evidence that a continuous reaction takes place in the growing Pr{sub 2}O{sub 3} film leading to the formation of silicate and silicide structures within the film. Combining all data, a consistent picture of the deposition of praseodymium oxide on Si(111) emerges which clearly shows that in contrast to higher-throughput molecular beam epitaxy conditions the reactivity of the growing film strongly influences the growth behavior at low-deposition rates and low pressures.

  7. Growth response of Casuarina equisetifolia Forst. rooted stem cuttings to Frankia in nursery and field conditions.

    PubMed

    Karthikeyan, A; Chandrasekaran, K; Geetha, M; Kalaiselvi, R

    2013-11-01

    Casuarina equisetifolia Forst. is a tree crop that provides fuel wood, land reclamation, dune stabilization, and scaffolding for construction, shelter belts, and pulp and paper production. C. equisetifolia fixes atmospheric nitrogen through a symbiotic relationship with Frankia, a soil bacterium of the actinobacteria group. The roots of C. equisetifolia produce root nodules where the bacteria fix atmospheric nitrogen, which is an essential nutrient for all plant metabolic activities. However, rooted stem cuttings of elite clones of C. equisetifolia by vegetative propagation is being planted by the farmers of Pondicherry as costeffective method. As the vegetative propagation method uses inert material (vermiculite) for rooting there is no chance for Frankia association. Therefore after planting of these stocks the farmers are applying 150 kg of di-ammonium phosphate (DAP)/acre/year. To overcome this fertilizer usage, the Frankia-inoculated rooted stem cuttings were propagated under nursery conditions and transplanted in the nutrient-deficient soils of Karaikal, Pondicherry (India), in this study. Under nursery experiments the growth and biomass of C. equisetifolia rooted stem cuttings inoculated with Frankia showed 3 times higher growth and biomass than uninoculated control. These stocks were transplanted and monitored for their growth and survival for 1 year in the nutrient-deficient farm land. The results showed that the rooted stem cuttings of C. equisetifolia significantly improved growth in height (8.8 m), stem girth (9.6 cm) and tissue nitrogen content (3.3 mg g-1) than uninoculated controls. The soil nutrient status was also improved due to inoculation of Frankia. PMID:24287654

  8. A comparison of hydrogen photoproduction by sulfur-deprived Chlamydomonas reinhardtii under different growth conditions.

    PubMed

    Kosourov, Sergey; Patrusheva, Elena; Ghirardi, Maria L; Seibert, Michael; Tsygankov, Anatoly

    2007-03-10

    Continuous photoproduction of H(2) by the green alga, Chlamydomonas reinhardtii, is observed after incubating the cultures for about a day in the absence of sulfate and in the presence of acetate. Sulfur deprivation causes the partial and reversible inactivation of photosynthetic O(2) evolution in algae, resulting in the light-induced establishment of anaerobic conditions in sealed photobioreactors, expression of two [FeFe]-hydrogenases in the cells, and H(2) photoproduction for several days. We have previously demonstrated that sulfur-deprived algal cultures can produce H(2) gas in the absence of acetate, when appropriate experimental protocols were used (Tsygankov, A.A., Kosourov, S.N., Tolstygina, I.V., Ghirardi, M.L., Seibert, M., 2006. Hydrogen production by sulfur-deprived Chlamydomonas reinhardtii under photoautotrophic conditions. Int. J. Hydrogen Energy 31, 1574-1584). We now report the use of an automated photobioreactor system to compare the effects of photoautotrophic, photoheterotrophic and photomixotrophic growth conditions on the kinetic parameters associated with the adaptation of the algal cells to sulfur deprivation and H(2) photoproduction. This was done under the experimental conditions outlined in the above reference, including controlled pH. From this comparison we show that both acetate and CO(2) are required for the most rapid inactivation of photosystem II and the highest yield of H(2) gas production. Although, the presence of acetate in the system is not critical for the process, H(2) photoproduction under photoautotrophic conditions can be increased by optimizing the conditions for high starch accumulation. These results suggest ways of engineering algae to improve H(2) production, which in turn may have a positive impact on the economics of applied systems for H(2) production. PMID:17275940

  9. Effects of Simulated Mars Conditions on the Survival and Growth of Escherichia coli and Serratia liquefaciens▿

    PubMed Central

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

    2010-01-01

    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°C) with increasing concentrations (0, 5, 10, or 20%) of three salts (MgCl2, MgSO4, 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°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% MgSO4 maintained at 20 or 30°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°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

  10. Comparison of Aerobic and Anaerobic Biodegradation of Sugarcane Vinasse.

    PubMed

    Mota, V T; Araújo, T A; Amaral, M C S

    2015-07-01

    Vinasse is the main liquid waste from ethanol production, and it has a considerable pollution potential. Biological treatment is a promising alternative to reduce its organic load. The aim of this study was to analyze the biodegradation of sugarcane juice vinasse in aerobic and anaerobic conditions. The content of carbohydrates, proteins and volatile fatty acids was evaluated. Vinasse samples showed a high biodegradability (>96.5 %) and low percentage of inert chemical oxygen demand (COD) (<3.2 %) in both aerobic and anaerobic conditions. The rates of substrate utilization were slightly higher in aerobic reactors, but COD stabilization occurred simultaneously in the anaerobic reactors, confirming its suitability for anaerobic digestion. Inert COD in anaerobic conditions was lower than in aerobic conditions. On the other hand, COD from metabolic products in the anaerobic reactors was higher than in the aerobic ones, indicating an increased release of soluble microbial products (SMPs) by anaerobic microorganisms. The results indicated that carbohydrates were satisfactorily degraded and protein-like substances were the major components remaining after biological degradation of vinasse. PMID:25957273

  11. Stochastic modeling of crack initiation and short-crack growth under creep and creep-fatigue conditions

    NASA Technical Reports Server (NTRS)

    Kitamura, Takayuki; Ghosn, Louis J.; Ohtani, Ryuichi

    1992-01-01

    A simplified stochastic model is proposed for crack initiation and short-crack growth under creep and creep-fatigue conditions. Material inhomogeneity provides the random nature of crack initiation and early growth. In the model, the influence of microstructure is introduced by the variability of: (1) damage accumulation along grain boundaries, (2) critical damage required for crack initiation or growth, and (3) the grain-boundary length. The probabilities of crack initiation and growth are derived by using convolution integrals. The model is calibrated and used to predict the crack density and crack-growth rate of short cracks of 304 stainless steel under creep and creep-fatigue conditions. The mean-crack initiation lives are predicted to be within an average deviation of about 10 percent from the experimental results. The predicted comulative distributions of crack-growth rate follow the experimental data closely. The applicability of the simplified stochastic model is discussed and the future research direction is outlined.

  12. Stochastic modeling of crack initiation and short-crack growth under creep and creep-fatigue conditions

    NASA Technical Reports Server (NTRS)

    Kitamura, Takayuki; Ghosn, Louis J.; Ohtani, Ryuichi

    1989-01-01

    A simplified stochastic model is proposed for crack initiation and short-crack growth under creep and creep-fatigue conditions. Material inhomogeneity provides the random nature of crack initiation and early growth. In the model, the influence of microstructure is introduced by the variability of: (1) damage accumulation along grain boundaries, (2) critical damage required for crack initiation or growth, and (3) the grain-boundary length. The probabilities of crack initiation and growth are derived by using convolution integrals. The model is calibrated and used to predict the crack density and crack-growth rate of short cracks of 304 stainless steel under creep and creep-fatigue conditions. The mean-crack initiation lives are predicted to be within an average deviation of about 10 percent from the experimental results. The predicted cumulative distributions of crack-growth rate follow the experimental data closely. The applicability of the simplified stochastic model is discussed and the future research direction is outlined.

  13. MYB10 and MYB72 are required for growth under iron-limiting conditions.

    PubMed

    Palmer, Christine M; Hindt, Maria N; Schmidt, Holger; Clemens, Stephan; Guerinot, Mary Lou

    2013-11-01

    Iron is essential for photosynthesis and is often a limiting nutrient for plant productivity. Plants respond to conditions of iron deficiency by increasing transcript abundance of key genes involved in iron homeostasis, but only a few regulators of these genes have been identified. Using genome-wide expression analysis, we searched for transcription factors that are induced within 24 hours after transferring plants to iron-deficient growth conditions. Out of nearly 100 transcription factors shown to be up-regulated, we identified MYB10 and MYB72 as the most highly induced transcription factors. Here, we show that MYB10 and MYB72 are functionally redundant and are required for plant survival in alkaline soil where iron availability is greatly restricted. myb10myb72 double mutants fail to induce transcript accumulation of the nicotianamine synthase gene NAS4. Both myb10myb72 mutants and nas4-1 mutants have reduced iron concentrations, chlorophyll levels, and shoot mass under iron-limiting conditions, indicating that these genes are essential for proper plant growth. The double myb10myb72 mutant also showed nickel and zinc sensitivity, similar to the nas4 mutant. Ectopic expression of NAS4 rescues myb10myb72 plants, suggesting that loss of NAS4 is the primary defect in these plants and emphasizes the importance of nicotianamine, an iron chelator, in iron homeostasis. Overall, our results provide evidence that MYB10 and MYB72 act early in the iron-deficiency regulatory cascade to drive gene expression of NAS4 and are essential for plant survival under iron deficiency. PMID:24278034

  14. Theoretical investigations of initial growth processes on semipolar AlN(11\\bar{2}2) surfaces under metal–organic vapor-phase epitaxy growth condition

    NASA Astrophysics Data System (ADS)

    Akiyama, Toru; Takemoto, Yoshitaka; Nakamura, Kohji; Ito, Tomonori

    2016-05-01

    The initial growth processes on semipolar AlN(11\\bar{2}2) surfaces, such as adsorption behavior of Al adatoms, are investigated on the basis of ab initio calculations and kinetic Monte Carlo (MC) simulations. By using surface phase diagrams, which are obtained by comparing the adsorption energy from ab initio calculations with gas-phase chemical potentials, we find that the adsorption of Al adatoms under H-poor condition is much easier than that under H-rich condition. Furthermore, our kinetic MC simulations demonstrate that the surface lifetime (diffusion length) of Al adatoms under H-poor condition is found to be four (two) orders of magnitude larger than that under H-rich condition. These differences implie that the growth under H-poor condition is much faster than that under H-rich condition, qualitatively consistent with the experimental results.

  15. FIS-dependent trans activation of stable RNA operons of Escherichia coli under various growth conditions.

    PubMed Central

    Nilsson, L; Verbeek, H; Vijgenboom, E; van Drunen, C; Vanet, A; Bosch, L

    1992-01-01

    In Escherichia coli transcription of the tRNA operon thrU (tufB) and the rRNA operon rrnB is trans-activated by the protein FIS. This protein, which stimulates the inversion of various viral DNA segments, binds specifically to a cis-acting sequence (designated UAS) upstream of the promoter of thrU (tufB) and the P1 promoter of the rrnB operon. There are indications that this type of regulation is representative for the regulation of more stable RNA operons. In the present investigation we have studied UAS-dependent transcription activation of the thrU (tufB) operon in the presence and absence of FIS during a normal bacterial growth cycle and after a nutritional shift-up. In early log phase the expression of the operon rises steeply in wild-type cells, whereafter it declines. Concomitantly, a peak of the cellular FIS concentration is observed. Cells in the stationary phase are depleted of FIS. The rather abrupt increase of transcription activation depends on the nutritional quality of the medium. It is not seen in minimal medium. After a shift from minimal to rich medium, a peak of transcription activation and of FIS concentration is measured. This peak gets higher as the medium gets more strongly enriched. We conclude that a correlation between changes of the UAS-dependent activation of the thrU (tufB) operon and changes of the cellular FIS concentration under a variety of experimental conditions exists. This correlation strongly suggests that the production of FIS responds to environmental signals, thereby trans-activating the operon. Cells unable to produce FIS (fis cells) also show an increase of operon transcription in the early log phase and after a nutritional shift-up, albeit less pronounced than that wild-type cells. Presumably it is controlled by the ribosome feedback regulatory system. cis activation of the operon by the upstream activator sequence is apparent in the absence of FIS. This activation is constant throughout the entire growth cycle and is

  16. FIS-dependent trans activation of stable RNA operons of Escherichia coli under various growth conditions.

    PubMed

    Nilsson, L; Verbeek, H; Vijgenboom, E; van Drunen, C; Vanet, A; Bosch, L

    1992-02-01

    In Escherichia coli transcription of the tRNA operon thrU (tufB) and the rRNA operon rrnB is trans-activated by the protein FIS. This protein, which stimulates the inversion of various viral DNA segments, binds specifically to a cis-acting sequence (designated UAS) upstream of the promoter of thrU (tufB) and the P1 promoter of the rrnB operon. There are indications that this type of regulation is representative for the regulation of more stable RNA operons. In the present investigation we have studied UAS-dependent transcription activation of the thrU (tufB) operon in the presence and absence of FIS during a normal bacterial growth cycle and after a nutritional shift-up. In early log phase the expression of the operon rises steeply in wild-type cells, whereafter it declines. Concomitantly, a peak of the cellular FIS concentration is observed. Cells in the stationary phase are depleted of FIS. The rather abrupt increase of transcription activation depends on the nutritional quality of the medium. It is not seen in minimal medium. After a shift from minimal to rich medium, a peak of transcription activation and of FIS concentration is measured. This peak gets higher as the medium gets more strongly enriched. We conclude that a correlation between changes of the UAS-dependent activation of the thrU (tufB) operon and changes of the cellular FIS concentration under a variety of experimental conditions exists. This correlation strongly suggests that the production of FIS responds to environmental signals, thereby trans-activating the operon. Cells unable to produce FIS (fis cells) also show an increase of operon transcription in the early log phase and after a nutritional shift-up, albeit less pronounced than that wild-type cells. Presumably it is controlled by the ribosome feedback regulatory system. cis activation of the operon by the upstream activator sequence is apparent in the absence of FIS. This activation is constant throughout the entire growth cycle and is

  17. Soil texture and climatc conditions for biocrust growth limitation: a meta analysis

    NASA Astrophysics Data System (ADS)

    Fischer, Thomas; Subbotina, Mariia

    2015-04-01

    Along with afforestation, attempts have been made to combat desertification by managing soil crusts, and is has been reported that recovery rates of biocrusts are dependent on many factors, including the type, severity, and extent of disturbance; structure of the vascular plant community; conditions of adjoining substrates; availability of inoculation material; and climate during and after disturbance (Belnap & Eldridge 2001). Because biological soil crusts are known to be more stable on and to prefer fine substrates (Belnap 2001), the question arises as to how successful crust management practices can be applied to coarser soil. In previous studies we observed similar crust biomasses on finer soils under arid and on coarser soils under temperate conditions. We hypothesized that the higher water holding capacity of finer substrates would favor crust development, and that the amount of silt and clay in the substrate that is required for enhanced crust development would vary with changes in climatic conditions. In a global meta study, climatic and soil texture threshold values promoting BSC growth were derived. While examining literature sources, it became evident that the amount of studies to be incorporated into this meta analysis was reversely related to the amount of common environmental parameters they share. We selected annual mean precipitaion, mean temperature and the amount of silt and clay as driving variables for crust growth. Response variable was the "relative crust biomass", which was computed per literature source as the ratio between each individual crust biomass value of the given study to the study maximum value reported. We distinguished lichen, green algal, cyanobacterial and moss crusts. To quantify threshold conditions at which crust biomass responded to differences in texture and climate, we (I) determined correlations between bioclimatic variables, (II) calculated linear models to determine the effect of typical climatic variables with soil

  18. Estimating geographic variation on allometric growth and body condition of Blue Suckers with quantile regression

    USGS Publications Warehouse

    Cade, B.S.; Terrell, J.W.; Neely, B.C.

    2011-01-01

    Increasing our understanding of how environmental factors affect fish body condition and improving its utility as a metric of aquatic system health require reliable estimates of spatial variation in condition (weight at length). We used three statistical approaches that varied in how they accounted for heterogeneity in allometric growth to estimate differences in body condition of blue suckers Cycleptus elongatus across 19 large-river locations in the central USA. Quantile regression of an expanded allometric growth model provided the most comprehensive estimates, including variation in exponents within and among locations (range = 2.88–4.24). Blue suckers from more-southerly locations had the largest exponents. Mixed-effects mean regression of a similar expanded allometric growth model allowed exponents to vary among locations (range = 3.03–3.60). Mean relative weights compared across selected intervals of total length (TL = 510–594 and 594–692 mm) in a multiplicative model involved the implicit assumption that allometric exponents within and among locations were similar to the exponent (3.46) for the standard weight equation. Proportionate differences in the quantiles of weight at length for adult blue suckers (TL = 510, 594, 644, and 692 mm) compared with their average across locations ranged from 1.08 to 1.30 for southern locations (Texas, Mississippi) and from 0.84 to 1.00 for northern locations (Montana, North Dakota); proportionate differences for mean weight ranged from 1.13 to 1.17 and from 0.87 to 0.95, respectively, and those for mean relative weight ranged from 1.10 to 1.18 and from 0.86 to 0.98, respectively. Weights for fish at longer lengths varied by 600–700 g within a location and by as much as 2,000 g among southern and northern locations. Estimates for the Wabash River, Indiana (0.96–1.07 times the average; greatest increases for lower weights at shorter TLs), and for the Missouri River from Blair, Nebraska, to Sioux City, Iowa (0.90

  19. Salmonella Modulates Metabolism during Growth under Conditions that Induce Expression of Virulence Genes

    PubMed Central

    Kim, Young-Mo; Schmidt, Brian J.; Kidwai, Afshan S.; Jones, Marcus B.; Deatherage Kaiser, Brooke L.; Brewer, Heather M.; Mitchell, Hugh D.; Palsson, Bernhard O.; McDermott, Jason E.; Heffron, Fred; Smith, Richard D.; Peterson, Scott N.; Ansong, Charles; Hyduke, Daniel R.; Metz, Thomas O.; Adkins, Joshua N.

    2013-01-01

    Salmonella enterica serovar Typhimurium (S. Typhimurium) is a facultative pathogen that uses complex mechanisms to invade and proliferate within mammalian host cells. To investigate possible contributions of metabolic processes to virulence in S. Typhimurium grown under conditions known to induce expression of virulence genes, we used a metabolomics-driven systems biology approach coupled with genome scale modeling. First, we identified distinct metabolite profiles associated with bacteria grown in either rich or virulence-inducing media and report the most comprehensive coverage of the S. Typhimurium metabolome to date. Second, we applied an omics-informed genome scale modeling analysis of the functional consequences of adaptive alterations in S. Typhimurium metabolism during growth under our conditions. Modeling efforts highlighted a decreased cellular capability to both produce and utilize intracellular amino acids during stationary phase culture in virulence conditions, despite significant abundance increases for these molecules as observed by our metabolomics measurements. Furthermore, analyses of omics data in the context of the metabolic model indicated rewiring of the metabolic network to support pathways associated with virulence. For example, cellular concentrations of polyamines were perturbed, as well as the predicted capacity for secretion and uptake. PMID:23559334

  20. Differential Carbohydrate Recognition by Campylobacter jejuni Strain 11168: Influences of Temperature and Growth Conditions

    PubMed Central

    Day, Christopher J.; Tiralongo, Joe; Hartnell, Regan D.; Logue, Carie-Anne; Wilson, Jennifer C.; von Itzstein, Mark; Korolik, Victoria

    2009-01-01

    The pathogenic clinical strain NCTC11168 was the first Campylobacter jejuni strain to be sequenced and has been a widely used laboratory model for studying C. jejuni pathogenesis. However, continuous passaging of C. jejuni NCTC11168 has been shown to dramatically affect its colonisation potential. Glycan array analysis was performed on C. jejuni NCTC11168 using the frequently passaged, non-colonising, genome sequenced (11168-GS) and the infrequently passaged, original, virulent (11168-O) isolates grown or maintained under various conditions. Glycan structures recognised and bound by C. jejuni included terminal mannose, N-acetylneuraminic acid, galactose and fucose. Significantly, it was found that only when challenged with normal oxygen at room temperature did 11168-O consistently bind to sialic acid or terminal mannose structures, while 11168-GS bound these structures regardless of growth/maintenance conditions. Further, binding of un-capped galactose and fucosylated structures was significantly reduced when C. jejuni was maintained at 25°C under atmospheric oxygen conditions. These binding differences identified through glycan array analysis were confirmed by the ability of specific lectins to competitively inhibit the adherence of C. jejuni to a Caco-2 intestinal cell line. Our data suggests that the binding of mannose and/or N-acetylneuraminic acid may provide the initial interactions important for colonisation following environmental exposure. PMID:19290056

  1. Salmonella Modulates Metabolism During Growth under Conditions that Induce Expression of Virulence Genes

    SciTech Connect

    Kim, Young-Mo; Schmidt, Brian; Kidwai, Afshan S.; Jones, Marcus B.; Deatherage, Brooke L.; Brewer, Heather M.; Mitchell, Hugh D.; Palsson, Bernhard O.; McDermott, Jason E.; Heffron, Fred; Smith, Richard D.; Peterson, Scott N.; Ansong, Charles; Hyduke, Daniel R.; Metz, Thomas O.; Adkins, Joshua N.

    2013-04-05

    Salmonella enterica serovar Typhimurium (S. Typhimurium) is a facultative pathogen that uses complex mechanisms to invade and proliferate within mammalian host cells. To investigate possible contributions of metabolic processes in S. Typhimurium grown under conditions known to induce expression of virulence genes, we used a metabolomics-driven systems biology approach coupled with genome scale modeling. First, we identified distinct metabolite profiles associated with bacteria grown in either rich or virulence-inducing media and report the most comprehensive coverage of the S. Typhimurium metabolome to date. Second, we applied an omics-informed genome scale modeling analysis of the functional consequences of adaptive alterations in S. Typhimurium metabolism during growth under our conditions. Excitingly, we observed possible sequestration of metabolites recently suggested to have immune modulating roles. Modeling efforts highlighted a decreased cellular capability to both produce and utilize intracellular amino acids during stationary phase culture in virulence conditions, despite significant abundance increases for these molecules as observed by our metabolomics measurements. Model-guided analysis suggested that alterations in metabolism prioritized other activities necessary for pathogenesis instead, such as lipopolysaccharide biosynthesis.

  2. Growth Conditions Control the Elastic and Electrical Properties of ZnO Nanowires.

    PubMed

    Wang, Xiaoguang; Chen, Kai; Zhang, Yongqiang; Wan, Jingchun; Warren, Oden L; Oh, Jason; Li, Ju; Ma, Evan; Shan, Zhiwei

    2015-12-01

    Great efforts have been made to synthesize ZnO nanowires (NWs) as building blocks for a broad range of applications because of their unique mechanical and mechanoelectrical properties. However, little attention has been paid to the correlation between the NWs synthesis condition and these properties. Here we demonstrate that by slightly adjusting the NW growth conditions, the cross-sectional shape of the NWs can be tuned from hexagonal to circular. Room temperature photoluminescence spectra suggested that NWs with cylindrical geometry have a higher density of point defects. In situ transmission electron microscopy (TEM) uniaxial tensile-electrical coupling tests revealed that for similar diameter, the Young's modulus and electrical resistivity of hexagonal NWs is always larger than that of cylindrical NWs, whereas the piezoresistive coefficient of cylindrical NWs is generally higher. With decreasing diameter, the Young's modulus and the resistivity of NWs increase, whereas their piezoresistive coefficient decreases, regardless of the sample geometry. Our findings shed new light on understanding and advancing the performance of ZnO-NW-based devices through optimizing the synthesis conditions of the NWs. PMID:26510098

  3. Growth conditions and environmental factors impact aerosolization but not virulence of Francisella tularensis infection in mice

    PubMed Central

    Faith, Seth A.; Smith, Le'Kneitah P.; Swatland, Angela S.; Reed, Douglas S.

    2012-01-01

    In refining methodology to develop a mouse model for inhalation of Francisella tularensis, it was noted that both relative humidity and growth media impacted the aerosol concentration of the live vaccine strain (LVS) of F. tularensis. A relative humidity of less than 55% had a negative impact on the spray factor, the ratio between the concentration of LVS in the aerosol and the nebulizer. The spray factor was significantly higher for LVS grown in brain heart infusion (BHI) broth than LVS grown in Mueller–Hinton broth (MHb) or Chamberlain's chemically defined medium (CCDM). The variability between aerosol exposures was also considerably less with BHI. LVS grown in BHI survived desiccation far longer than MHb-grown or CCDM-grown LVS (~70% at 20 min for BHI compared to <50% for MHb and CCDM). Removal of the capsule by hypertonic treatment impacted the spray factor for CCDM-grown LVS or MHb-grown LVS but not BHI-grown LVS, suggesting the choice of culture media altered the adherence of the capsule to the cell membrane. The choice of growth media did not impact the LD50 of LVS but the LD99 of BHI-grown LVS was 1 log lower than that for MHb-grown LVS or CCDM-grown LVS. Splenomegaly was prominent in mice that succumbed to MHb- and BHI-grown LVS but not CCDM-grown LVS. Environmental factors and growth conditions should be evaluated when developing new animal models for aerosol infection, particularly for vegetative bacterial pathogens. PMID:23087911

  4. Growth responses of the mangrove Avicennia marina to salinity: development and function of shoot hydraulic systems require saline conditions

    PubMed Central

    Nguyen, Hoa T.; Stanton, Daniel E.; Schmitz, Nele; Farquhar, Graham D.; Ball, Marilyn C.

    2015-01-01

    Background and Aims Halophytic eudicots are characterized by enhanced growth under saline conditions. This study combines physiological and anatomical analyses to identify processes underlying growth responses of the mangrove Avicennia marina to salinities ranging from fresh- to seawater conditions. Methods Following pre-exhaustion of cotyledonary reserves under optimal conditions (i.e. 50 % seawater), seedlings of A. marina were grown hydroponically in dilutions of seawater amended with nutrients. Whole-plant growth characteristics were analysed in relation to dry mass accumulation and its allocation to different plant parts. Gas exchange characteristics and stable carbon isotopic composition of leaves were measured to evaluate water use in relation to carbon gain. Stem and leaf hydraulic anatomy were measured in relation to plant water use and growth. Key Results Avicennia marina seedlings failed to grow in 0–5 % seawater, whereas maximal growth occurred in 50–75 % seawater. Relative growth rates were affected by changes in leaf area ratio (LAR) and net assimilation rate (NAR) along the salinity gradient, with NAR generally being more important. Gas exchange characteristics followed the same trends as plant growth, with assimilation rates and stomatal conductance being greatest in leaves grown in 50–75 % seawater. However, water use efficiency was maintained nearly constant across all salinities, consistent with carbon isotopic signatures. Anatomical studies revealed variation in rates of development and composition of hydraulic tissues that were consistent with salinity-dependent patterns in water use and growth, including a structural explanation for low stomatal conductance and growth under low salinity. Conclusions The results identified stem and leaf transport systems as central to understanding the integrated growth responses to variation in salinity from fresh- to seawater conditions. Avicennia marina was revealed as an obligate halophyte

  5. Improved TNT detoxification by starch addition in a nitrogen-fixing Methylophilus-dominant aerobic microbial consortium.

    PubMed

    Khan, Muhammad Imran; Lee, Jaejin; Yoo, Keunje; Kim, Seonghoon; Park, Joonhong

    2015-12-30

    In this study, a novel aerobic microbial consortium for the complete detoxification of 2,4,6-trinitrotoluene (TNT) was developed using starch as a slow-releasing carbon source under nitrogen-fixing conditions. Aerobic TNT biodegradation coupled with microbial growth was effectively stimulated by the co-addition of starch and TNT under nitrogen-fixing conditions. The addition of starch with TNT led to TNT mineralization via ring cleavage without accumulation of any toxic by-products, indicating improved TNT detoxification by the co-addition of starch and TNT. Pyrosequencing targeting the bacterial 16S rRNA gene suggested that Methylophilus and Pseudoxanthomonas population were significantly stimulated by the co-addition of starch and TNT and that the Methylophilus population became predominant in the consortium. Together with our previous study regarding starch-stimulated RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) degradation (Khan et al., J. Hazard. Mater. 287 (2015) 243-251), this work suggests that the co-addition of starch with a target explosive is an effective way to stimulate aerobic explosive degradation under nitrogen-fixing conditions for enhancing explosive detoxification. PMID:26342802

  6. Comprehensive Study Of Duckweed Cultivation And Growth Conditions Under Controlled Eutrophication

    NASA Astrophysics Data System (ADS)

    Bartošová, Alica; Sirotiak, Maroš; Fiala, Jozef

    2015-06-01

    The paper discussed the issue of eutrophication. The most conspicuous effect of eutrophication is the creation of dense blooms of noxious, foul-smelling phytoplankton that reduce water clarity and harm water quality. Nutrient concentration, temperature and pH of the water largely influence the growth rate and composition of duckweed in general, but it can be said that the temperature and solar irradiation are the most important factors. In order to compare the rate of biomass increase of duckweed biomass in natural conditions and in a laboratory grown sample was analysed by spectrophotometric methods in UV/VIS region (Spectrophotometer GENESYSTM) for the selected nutrients such as ammonium, ammonium nitrogen, nitrite, nitrate, and phosphate.

  7. A new fungal endophyte, Scolecobasidium humicola, promotes tomato growth under organic nitrogen conditions.

    PubMed

    Mahmoud, Rola S; Narisawa, Kazuhiko

    2013-01-01

    A new fungal endophyte, Scolecobasidium humicola, was identified as a common dark septate endophytic fungal (DSE) species under both natural and agricultural conditions. This fungus was found to grow endophylically in the roots of tomato seedlings. Light microscopy of cross-sections of colonized tomato roots showed that the intercellular, pigmented hyphae of the fungus were mostly limited to the epidermal layer and formed outer mantle-like structures. Two isolates of S. humicola, H2-2 and F1-3, have shown the ability to increase plant biomass with an organic nitrogen source. This finding is the first report of S. humicola as an endophyte and could help to improve plant growth with organic nitrogen sources. PMID:24223848

  8. Lipid production on free fatty acids by oleaginous yeasts under non-growth conditions.

    PubMed

    Yang, Xiaobing; Jin, Guojie; Wang, Yandan; Shen, Hongwei; Zhao, Zongbao K

    2015-10-01

    Microbial lipids produced by oleaginous yeasts serve as promising alternatives to traditional oils and fats for the production of biodiesel and oleochemicals. To improve its techno-economics, it is pivotal to use wastes and produce high quality lipids of special fatty acid composition. In the present study, four oleaginous yeasts were tested to use free fatty acids for lipid production under non-growth conditions. Microbial lipids of exceptionally high fatty acid relative contents, e.g. those contained over 70% myristic acid or 80% oleic acid, were produced that may be otherwise inaccessible by growing cells on various carbon sources. It was found that Cryptococcus curvatus is a robust strain that can efficiently use oleic acid as well as even-numbered saturated fatty acids with carbon atoms ranging from 10 to 20. Our results provided new opportunity for the production of functional lipids and for the exploitation of organic wastes rich in free fatty acids. PMID:26159379

  9. Interactive effects of shelter and conspecific density shape mortality, growth, and condition in juvenile reef fish.

    PubMed

    Ford, John R; Shima, Jeffrey S; Swearer, Stephen E

    2016-06-01

    How landscape context influences density-dependent processes is important, as environmental heterogeneity can confound estimates of density dependence in demographic parameters. Here we evaluate 19 populations in a shoaling temperate reef fish (Trachinops caudimaculatus) metapopulation within a heterogeneous seascape (Port Phillip Bay, Australia) to show empirically that shelter availability and population density interact to influence juvenile mortality, growth and condition. Although heterogeneity in shelter availability obscured the underlying patterns of density dependence in different ways, the combination of habitat and its interaction with density were two to six times more important than density alone in explaining variation in demographic parameters for juveniles. These findings contradict many small-scale studies and highlight the need for landscape-scale observations of how density dependence interacts with resource availability and competition to better understand how demographic parameters influence the dynamics of metapopulations in heterogeneous environments. PMID:27459768

  10. Comorbid Medical Conditions in Friedreich Ataxia: Association With Inflammatory Bowel Disease and Growth Hormone Deficiency.

    PubMed

    Shinnick, Julianna E; Schadt, Kimberly; Strawser, Cassandra; Wilcox, Nicholas; Perlman, Susan L; Wilmot, George R; Gomez, Christopher M; Mathews, Katherine D; Yoon, Grace; Zesiewicz, Theresa; Hoyle, Chad; Subramony, S H; Yiu, Eppie M; Delatycki, Martin B; Brocht, Alicia F; Farmer, Jennifer M; Lynch, David R

    2016-08-01

    Friedreich ataxia is a progressive degenerative disease with neurologic and cardiac involvement. This study characterizes comorbid medical conditions in a large cohort of patients with Friedreich ataxia. Patient diagnoses were collected in a large natural history study of 641 subjects. Prevalence of diagnoses in the cohort with Friedreich ataxia was compared with prevalence in the population without Friedreich ataxia. Ten patients (1.6%) had inflammatory bowel disease, 3.5 times more common in this cohort of individuals with Friedreich ataxia than in the general population. Four subjects were growth hormone deficient, reflecting a prevalence in Friedreich ataxia that is 28 times greater than the general population. The present study identifies specific diagnoses not traditionally associated with Friedreich ataxia that are found at higher frequency in this disease. These associations could represent coincidence, shared genetic background, or potentially interactive disease mechanisms with Friedreich ataxia. PMID:27071470

  11. A New Fungal Endophyte, Scolecobasidium humicola, Promotes Tomato Growth under Organic Nitrogen Conditions

    PubMed Central

    Mahmoud, Rola S.; Narisawa, Kazuhiko

    2013-01-01

    A new fungal endophyte, Scolecobasidium humicola, was identified as a common dark septate endophytic fungal (DSE) species under both natural and agricultural conditions. This fungus was found to grow endophylically in the roots of tomato seedlings. Light microscopy of cross-sections of colonized tomato roots showed that the intercellular, pigmented hyphae of the fungus were mostly limited to the epidermal layer and formed outer mantle-like structures. Two isolates of S. humicola, H2-2 and F1-3, have shown the ability to increase plant biomass with an organic nitrogen source. This finding is the first report of S. humicola as an endophyte and could help to improve plant growth with organic nitrogen sources. PMID:24223848

  12. Exploring growth conditions and Eu2+ concentration effects for KSr2I5:Eu scintillator crystals

    NASA Astrophysics Data System (ADS)

    Stand, L.; Zhuravleva, M.; Camarda, G.; Lindsey, A.; Johnson, J.; Hobbs, C.; Melcher, C. L.

    2016-04-01

    Our current research is focused on understanding dopant optimization, growth rate, homogeneity and their impact on the overall performance of KSr2I5:Eu2+ single crystal scintillators. In this work we have investigated the effects of Eu2+ concentration in the potassium strontium iodide matrix, and we found that the concentration needed to maximize the light yield was 4 mol%. In order to assess the effects of the pulling rate, we grew single crystals at 12, 24 and 120 mm/day via the vertical Bridgman technique. For the sample sizes measured (5×5×5 mm3), we found that the crystal grown at the fastest rate of 120 mm/day showed a light yield within ~7% of the more slowly grown boules, and no significant change was observed in the energy resolution. Therefore, light yields from 88,000 to 96,000 ph/MeV and energy resolutions from 2.4 to 3.0% (at 662 keV) were measured for KSr2I5:Eu 4% over a relatively wide range of growth conditions. In order to assess the homogeneity of KSr2I5:Eu 4%, a newly developed micro-resolution X-ray technique was used to map the light yield as a function of excitation position. In the crystals that we studied, we did not observe any significant inhomogeneity other than a smooth gradient due to light collection and self absorption effects.

  13. Outer Membrane Proteome of Burkholderia pseudomallei and Burkholderia mallei From Diverse Growth Conditions

    PubMed Central

    Schell, Mark A.; Zhao, Peng; Wells, Lance

    2016-01-01

    Burkholderia mallei and Burkholderia pseudomallei are closely related, aerosol-infective human pathogens that cause life-threatening diseases. Biochemical analyses requiring large-scale growth and manipulation at biosafety level 3 under select agent regulations are cumbersome and hazardous. We developed a simple, safe, and rapid method to prepare highly purified outer membrane (OM) fragments from these pathogens. Shotgun proteomic analyses of OMs by trypsin shaving and mass spectrometry identified >155 proteins, the majority of which are clearly outer membrane proteins (OMPs). These included: 13 porins, 4 secretins for virulence factor export, 11 efflux pumps, multiple components of a Type VI secreton, metal transport receptors, polysaccharide exporters, and hypothetical OMPs of unknown function. We also identified 20 OMPs in each pathogen that are abundant under a wide variety of conditions, including in serum and with macrophages, suggesting these are fundamental for growth and survival and may represent prime drug or vaccine targets. Comparison of the OM proteomes of B. mallei and B. pseudomallei showed many similarities but also revealed a few differences, perhaps reflecting evolution of B. mallei away from environmental survival toward host-adaptation. PMID:21391724

  14. Development of a Fatigue Crack Growth Coupon for Highly Plastic Stress Conditions

    NASA Technical Reports Server (NTRS)

    Allen, Phillip A.; Aggarwal, Pravin K.; Swanson, Gregory R.

    2003-01-01

    This paper presents an analytical approach used to develop a novel fatigue crack growth coupon for a highly plastic 3-D stress field condition. The flight hardware investigated in this paper is a large separation bolt that fractures using pyrotechnics at the appointed time during the flight sequence. The separation bolt has a deep notch that produces a severe stress concentration and a large plastic zone when highly loaded. For this geometry, linear-elastic fracture mechanics (LEFM) techniques are not valid due to the large nonlinear stress field. Unfortunately, industry codes that are generally available for fracture mechanics analysis and fatigue crack growth (e.g. NASGRO (11) are limited to LEFM and are available for only a limited number of geometries. The results of LEFM based codes are questionable when used on geometries with significant plasticity. Therefore elastic-plastic fracture mechanics (EPFM) techniques using the finite element method (FEM) were used to analyze the bolt and test coupons. scale flight hardware is very costly in t e r n of assets, laboratory resources, and schedule. Therefore to alleviate some of these problems, a series of novel test coupons were developed to simulate the elastic-plastic stress field present in the bolt.

  15. Optimization of culture conditions to obtain maximal growth of penicillin-resistant Streptococcus pneumoniae

    PubMed Central

    Restrepo, Andrea V; Salazar, Beatriz E; Agudelo, María; Rodriguez, Carlos A; Zuluaga, Andres F; Vesga, Omar

    2005-01-01

    Background Streptococcus pneumoniae, particularly penicillin-resistant strains (PRSP), constitute one of the most important causes of serious infections worldwide. It is a fastidious microorganism with exquisite nutritional and environmental requirements to grow, a characteristic that prevents the development of useful animal models to study the biology of the microorganism. This study was designed to determine optimal conditions for culture and growth of PRSP. Results We developed a simple and reproducible method for culture of diverse strains of PRSP representing several invasive serotypes of clinical and epidemiological importance in Colombia. Application of this 3-step culture protocol consistently produced more than 9 log10 CFU/ml of viable cells in the middle part of the logarithmic phase of their growth curve. Conclusion A controlled inoculum size grown in 3 successive steps in supplemented agar and broth under 5% CO2 atmosphere, with pH adjustment and specific incubation times, allowed production of great numbers of PRSP without untimely activation of autolysis mechanisms. PMID:15932633

  16. Natural variation in Arabidopsis adaptation to growth at low nitrogen conditions.

    PubMed

    North, Kathryn Anne; Ehlting, Barbara; Koprivova, Anna; Rennenberg, Heinz; Kopriva, Stanislav

    2009-10-01

    Improving nutrient use efficiency of crop plants, especially at low input, is essential to ensure sustainable food production in the future. In order to address the genetic basis of nutrient use efficiency in a model system, growth of Arabidopsis ecotypes at normal and low nitrogen (N) supply was compared. The ecotypes differed significantly in the extent of growth reduction in limiting conditions. The fresh weight of Shahdara and Ws grown at 1mM nitrate was reduced by 30% compared to control, whereas Col-0 and Ga-0 were almost unaffected. Total N content was reduced in all ecotypes by 10-30%. The capacity to store nitrate correlated with the tolerance to low N; in Shahdara and Ws, but not in Col-0 and Ga-0, nitrate content on low N was significantly reduced compared to control nutrition. The mRNA levels for genes of nitrate uptake and assimilation were only moderately affected by the treatment. The transcript levels of nitrate reductase NIA1 and nitrite reductase were higher in the ecotypes tolerant to low N (Col-0 and Ga-0) with normal N nutrition but on low N they were reduced to a much higher extent than the sensitive ecotypes (Shahdara and Ws). It seems that a higher capacity to keep nitrate reserves at low N, perhaps due to the ability to turn down nitrate reduction rate, is responsible for a better tolerance of Col-0 and Ga-0 to low N supply. PMID:19628403

  17. Arabidopsis alcohol dehydrogenase expression in both shoots and roots is conditioned by root growth environment

    NASA Technical Reports Server (NTRS)

    Chung, H. J.; Ferl, R. J.

    1999-01-01

    It is widely accepted that the Arabidopsis Adh (alcohol dehydrogenase) gene is constitutively expressed at low levels in the roots of young plants grown on agar media, and that the expression level is greatly induced by anoxic or hypoxic stresses. We questioned whether the agar medium itself created an anaerobic environment for the roots upon their growing into the gel. beta-Glucuronidase (GUS) expression driven by the Adh promoter was examined by growing transgenic Arabidopsis plants in different growing systems. Whereas roots grown on horizontal-positioned plates showed high Adh/GUS expression levels, roots from vertical-positioned plates had no Adh/GUS expression. Additional results indicate that growth on vertical plates closely mimics the Adh/GUS expression observed for soil-grown seedlings, and that growth on horizontal plates results in induction of high Adh/GUS expression that is consistent with hypoxic or anoxic conditions within the agar of the root zone. Adh/GUS expression in the shoot apex is also highly induced by root penetration of the agar medium. This induction of Adh/GUS in shoot apex and roots is due, at least in part, to mechanisms involving Ca2+ signal transduction.

  18. Effects of culture conditions on growth and docosahexaenoic acid production from Schizochytrium limacinum

    NASA Astrophysics Data System (ADS)

    Zhu, Luying; Zhang, Xuecheng; Ren, Xueying; Zhu, Qinghua

    2008-02-01

    The effects of temperature, initial pH, salinity of culture medium, and carbon and nitrogen sources on growth and docosahexaenoic acid (C22: 6 n-3, DHA) production from Schizochytrium limacinum OUC88 were investigated in the present study. The results revealed that the optimal temperature, initial pH and salinity level of the medium for DHA production were 23°C, 7.0 and 18, respectively. Glucose was proved the best carbon source for the growth and DHA production from S. limacinum. Among the nitrogen sources tested, soybean cake hydrolysate, a cheap by-product, was found to be effective for the accumulation of DHA in S. limacinum cells. In addition, increasing the concentration of carbon sources in the medium caused a significant increase in cell biomass; however, accumulation of DHA in cells was mainly stimulated by the ratio of C/N in the medium. Under the optimal culture conditions, the maximum DHA yield achieved in flasks was 4.08 g L-1 after 5 d of cultivation.

  19. THIAMINE AND NICOTINIC ACID: ANAEROBIC GROWTH FACTORS FOR MUCOR ROUXII

    PubMed Central

    Bartnicki-Garcia, S.; Nickerson, Walter J.

    1961-01-01

    Bartnicki-Garcia, S. (Rutgers, the State University, New Brunswick, N. J.), and Walter J. Nickerson. Thiamine and nicotinic acid: Anaerobic growth factors for Mucor rouxii. J. Bacteriol. 82:142–148. 1961.—Mucor rouxii requires preformed thiamine and nicotinic acid for anaerobic growth. Such requirements are not manifested during aerobic incubation. Aerobically, the fungus was shown to be able to synthesize both vitamins. The yeastlike form and the filamentous form of anaerobically grown M. rouxii exhibit the same vitamin requirements. Thiamine can be substituted by its thiazole moiety. Under certain conditions, nicotinic acid was partly substituted by tryptophan, kynurenine, 3-hydroxykynurenine, and 3-hydroxyanthranilic acid. Anaerobically. the fungus (thiamine requiring) was about ten times more susceptible to pyrithiamine antagonism than the same organism grown aerobically (thiamine independent). PMID:16561911

  20. Temporal Evolution of Magma Flow Conditions during Dome Growth, Insights from Numerical Modelling.

    NASA Astrophysics Data System (ADS)

    Chevalier, L. A. C.; Collombet, M.; Pinel, V.

    2015-12-01

    Transitions from effusive to explosive regime at andesitic volcanoes are almost unpredictable at the moment. The reliability of empirical methods based on geophysical precursory patterns is still debated. A better understanding of the physical processes happening in the volcanic system before explosions and associated geophysical signals is needed. At andesitic volcanoes, dome building is often observed during the effusive phase. The weight of a forming dome is expected to have several effects: 1) It obviously induces a ground subsidence in the near field; 2) pressure increase at the top of the conduit causes magma properties and flow conditions evolution; 3) it increases pressure in the surrounding rock such decreasing rock permeability and thus gas loss through the conduit walls, possibly leading to gas pressurisation. Here we use numerical models that couple realistic magma flow conditions in the upper conduit with solid deformation, in 2D axisymmetry, to investigate all these effects. Subsiding effect due to the dome emplacement is simulated by a pressure loading of the rock surrounding the conduit. From realistic initial magma flow conditions in effusive regime (Collombet, 2009), we apply increasing pressure at the conduit top. Volatile solubility increases with pressure, then dome growth causes a decrease of magma porosity and permeability at the top of the conduit. This also causes a decrease of magma viscosity. From magma flow model, we extract pressure and shear stress conditions at the conduit wall, and apply them to the surrounding rock for ground deformation calculation . Darcy flow model is used to study the impacts of permeability decrease inside the conduit and in the surrounding rock on gas loss cinematics. Permeability decrease in the conduit and pressure increase in the surrounding rock cause gas pressurisation.

  1. Aerobic and anaerobic microbiology of infections after trauma in children.

    PubMed Central

    Brook, I

    1998-01-01

    OBJECTIVE: To review the recovery of aerobic and anaerobic bacteria from infections after trauma in children over a 20 year period. METHODS: Only specimens that were studied for both aerobic and anaerobic bacteria were included in the analysis. They were collected from seven separate centres in which the microbiology laboratories only accepted specimens that were properly collected without contamination and were submitted in appropriate transport media. Anaerobes and aerobic bacteria were cultured and identified using standard techniques. Clinical records were reviewed to identify post-trauma patients. RESULTS: From 1974 to 1994, 175 specimens obtained from 166 children with trauma showed bacterial growth. The trauma included blunt trauma (71), lacerations (48), bites (42), and open fractures (5). Anaerobic bacteria only were isolated in 38 specimens (22%), aerobic bacteria only in 51 (29%), and mixed aerobic-anaerobic flora in 86 (49%); 363 anaerobic (2.1/specimen) and 158 aerobic or facultative isolates (0.9/specimen) were recovered. The predominant anaerobic bacteria included Peptostreptococcus spp (115 isolates), Prevotella spp (68), Fusobacterium spp (52), B fragilis group (42), and Clostridium spp (21). The predominant aerobic bacteria included Staph aureus (51), E coli (13), Ps aeruginosa (12), Str pyogenes (11) and Klebsiella pneumoniae (9). Principal infections were: abscesses (52), bacteraemia (3), pulmonary infections (30, including aspiration pneumonia, tracheostomy associated pneumonia, empyema, and ventilator associated pneumonia), wounds (36, including cellulitis, post-traumatic wounds, decubitus ulcers, myositis, gastrostomy and tracheostomy site wounds, and fasciitis), bites (42, including 23 animal and 19 human), peritonitis (4), osteomyelitis (5), and sinusitis (3). Staph aureus and Str pyogenes were isolated at all sites. However, organisms of the oropharyngeal flora predominated in infections that originated from head and neck wounds and

  2. How do sink and source activities influence the reproduction and vegetative growth of spring ephemeral herbs under different light conditions?

    PubMed

    Sunmonu, Ninuola; Kudo, Gaku

    2014-07-01

    Spring ephemeral herbs inhabiting deciduous forests commonly complete reproduction and vegetative growth before canopy closure in early summer. Effects of shading by early canopy closure on reproductive output and vegetative growth, however, may vary depending on the seasonal allocation patterns of photosynthetic products between current reproduction and storage for future growth in each species. To clarify the effects of sink-source balance on seed production and bulb growth in a spring ephemeral herb, Gagea lutea, we performed a bract removal treatment (source reduction) and a floral-bud removal treatment (sink reduction) under canopy and open conditions. Leaf carbon fixations did not differ between the forest and open sites and among treatments. Bract carbon fixations were also similar between sites but tended to decrease when floral buds were removed. Seed production was higher under open condition but decreased by the bract-removal treatment under both light conditions. In contrast, bulb growth was independent of light conditions and the bract-removal treatment but increased greatly by the bud-removal treatment. Therefore, leaves and bracts acted as specialized source organs for vegetative and reproductive functions, respectively, but photosynthetic products by bracts were flexibly used for bulb growth when plants failed to set fruits. Extension of bright period was advantageous for seed production (i.e., source limited) but not for vegetative growth (i.e., sink limited) in this species. PMID:24879401

  3. Growth and toxin production of Azadinium poporum strains in batch cultures under different nutrient conditions.

    PubMed

    Li, Aifeng; Jiang, Baozhou; Chen, Huidan; Gu, Haifeng

    2016-05-01

    Azaspiracid-2 (AZA2) is the dominant toxin produced by Azadinium poporum strains AZDY06 and AZFC22 isolated from the South China Sea. Biomass and AZA2-production were examined within batch cultures with variation in experimental concentrations of nitrate (0, 88, 882, and 2647µM) or phosphate (0, 3.6, 36, and 109µM), different nitrogen sources (nitrate and urea) and media (f/2-Si, L1-Si, and K-Si) in the present study. Growth of both strains positively responded to nitrate or phosphate nutrients, but the growth status was significantly repressed by the highest additional level of phosphate (109µM). Both AZDY06 and AZFC22 grew well with higher specific growth rates, but with shorter growth periods, within f/2-Si medium spiked with urea than that within media spiked with nitrate. L1-Si medium with relatively high concentrations of trace metals was relatively favorable to both strains of A. poporum tested here. No obvious change within the toxin profile occurred in all cultures of both strains under the various nutrient conditions, although trace amounts of some suspicious derivatives of AZA2 occurred in some cultures. AZA2 cell quotas within both strains significantly (p<0.05) increased at the stationary phase under lower additional phosphate (0 and 3.6µM). Significant differences were not found within AZA2 cell quotas in cultures with additional nitrate ranging from 0 to 2647µM. The highest AZA2 cell quota and maximum AZA2 quantity per culture volume occurred in batch culture at the stationary phase under phosphate concentrations at 3.6µM. Neither A. poporum strain exhibited significant changes in AZA2 cell quotas within f/2-Si media spiked with urea or nitrate as nitrogen sources. The AZA2 cell quota of strain AZDY06 also did not change remarkably within f/2-Si, L1-Si, and K-Si media, however the AZA2 cell quota of strain AZFC22 within L1-Si medium was significantly (p<0.05) higher than that within f/2-Si medium. PMID:26820226

  4. What are the differences between aerobic and anaerobic toxic effects of sulfonamides on Escherichia coli?

    PubMed

    Qin, Mengnan; Lin, Zhifen; Wang, Dali; Long, Xi; Zheng, Min; Qiu, Yanling

    2016-01-01

    Bacteria in the environment face the threat of antibiotics. However, most studies investigating the toxicity and toxicity mechanisms of antibiotics have been conducted on microorganisms in aerobic conditions, while studies examining the anaerobic toxicity and toxicity mechanisms of antibiotics are still limited. In this study, we determined the aerobic and anaerobic toxicities of sulfonamides (SAs) on Escherichia coli. Next, a comparison of the aerobic and anaerobic toxicities indicated that the SAs could be divided into three groups: Group I: log(1/EC50-anaerobic)>log(1/EC50-aerobic) (EC50-anaerobic/EC50-aerobic, the median effective concentration under anaerobic/aerobic conditions), Group II: log(1/EC50-anaerobic)≈log(1/EC50-aerobic), and Group III: log(1/EC50-anaerobic)aerobic). Furthermore, this division was not based on the reactive oxygen species (ROS) level or the interaction energy (Ebinding) value, which represents the affinity between SAs and dihydropteroate synthase (dhps) but rather on the total binding energy. Furthermore, SAs with greatly similar structures were categorized into different groups. This deep insight into the difference between aerobic and anaerobic toxicities will benefit environmental science, and the results of this study will serve as a reference for the risk assessment of chemicals in the environment. PMID:26748048

  5. A gene homologous to beta-type carbonic anhydrase is essential for the growth of Corynebacterium glutamicum under atmospheric conditions.

    PubMed

    Mitsuhashi, S; Ohnishi, J; Hayashi, M; Ikeda, M

    2004-02-01

    Carbonic anhydrase catalyzes the interconversion of CO(2) and bicarbonate. We focused on this enzyme in the amino acid-producing organism Corynebacterium glutamicum in order to assess the availability of bicarbonate for carboxylation reactions essential to growth and for those required for L-lysine overproduction. A whole-genome sequence revealed two genes encoding putative beta-type and gamma-type carbonic anhydrases in C. glutamicum. These genes encode polypeptides containing zinc ligands strictly conserved in each type of carbonic anhydrase and were designated bca and gca, respectively. Internal deletion of the chromosomal bca gene resulted in a phenotype showing severely reduced growth under atmospheric conditions (0.04% CO(2)) on both complete and minimal media. The growth defect of the Delta bca strain was restored under elevated CO(2) conditions (5% CO(2)). Introduction of the red alga Porphyridium purpureum carbonic anhydrase gene ( pca) could compensate for the bca deletion, allowing normal growth under an atmospheric level of CO(2). In contrast, the Delta gca strain behaved identically to the wild-type strain with respect to growth, irrespective of the CO(2) conditions. Attempts to increase the dosage of bca, gca, and pca in the defined L-lysine-producing strain C. glutamicum AHD-2 led to no discernable effects on growth and production. Northern blot analysis indicated that the bca transcript in strain AHD-2 and another L-lysine producer, C. glutamicum B-6, was present at a much higher level than in the wild-type strain, particularly during exponential growth phases. These results indicate that: (1) the bca product is essential to achieving normal growth under ordinary atmospheric conditions, and this effect is most likely due to the bca product's ability to maintain favorable intracellular bicarbonate/CO(2) levels, and (2) the expression of bca is induced during exponential growth phases and also in the case of L-lysine overproduction, both of which are

  6. Influence of rotating magnetic fields on THM growth of CdZnTe crystals under microgravity and ground conditions

    NASA Astrophysics Data System (ADS)

    Stelian, Carmen; Duffar, Thierry

    2015-11-01

    The influence of rotating magnetic fields (RMF) on species transport and interface stability during the growth of Cd0.96Zn0.04Te:In crystals by using the traveling heater method (THM), under microgravity and terrestrial conditions, is numerically investigated. The numerical results are compared to ground and space experiments. The modeling of THM under ground conditions shows very deleterious effects of the natural convection on the morphological stability of the growth interface. The vertical flow transports the liquid of low Te concentration from the dissolution interface to the growth interface, which is consequently destabilized. The suppression of this flow, in low-gravity conditions, results in higher morphological stability of the growth interface. Application of RMF induces a two flow cell pattern, which has a destabilizing effect on the growth interface. Simulations performed by varying the magnetic field induction in the range of 1 - 3 mT show optimal conditions for the growth with a stable interface at low strength of the magnetic field (B = 1 mT). Computations of indium distribution show a better homogeneity of crystals grown under purely diffusive conditions. Rotating magnetic fields of B = 1 mT induce low intensity convection, which generates concentration gradients near the growth interface. These numerical results are in agreement with experiments performed during the FOTON M4 space mission, showing good structural quality of Cd0.96Zn0.04Te crystals grown at very low gravity level. Applying low intensity rotating magnetic fields in ground experiments has no significant influence on the flow pattern and solute distribution. At high intensity of RMF (B = 50 mT), the buoyancy convection is damped near the growth front, resulting in a more stable advancing interface. However, convection is strengthening in the upper part of the liquid zone, where the flow becomes unsteady. The multi-cellular unsteady flow generates temperature oscillations, having

  7. Bridgman Crystal Growth of an Alloy with Thermosolutal Convection Under Microgravity Conditions

    NASA Technical Reports Server (NTRS)

    Simpson, James E.; Garimella, Suresh V.; deGroh, Henry C., III; Abbaschian, Reza

    2000-01-01

    The solidification of a dilute alloy (bismuth-tin) under Bridgman crystal growth conditions is investigated. Computations are performed in two dimensions with a uniform grid. The simulation includes the species concentration, temperature and flow fields, as well as conduction in the ampoule. Fully transient simulations have been performed, with no simplifying steady state approximations. Results are obtained under microgravity conditions for pure bismuth, and for Bi-0.1 at.%Sn and Bi-1.0 at.%Sn alloys, and compared with experimental results obtained from crystals grown in the microgravity environment of space. For the Bi-1.0 at.%Sn case the results indicate that a secondary convective cell, driven by solutal gradients, forms near the interface. The magnitude of the velocities in this cell increases with time, causing increasing solute segregation at the solid/liquid interface. The concentration-dependence of the melting temperature is incorporated in the model for the Bi-1.0 at.%Sn alloy. Satisfactory correspondence is obtained between the predicted and experimental results in terms of solute concentrations in the solidified crystal.

  8. Solution conditions determine the relative importance of nucleation and growth processes in α-synuclein aggregation

    PubMed Central

    Buell, Alexander K.; Galvagnion, Céline; Gaspar, Ricardo; Sparr, Emma; Vendruscolo, Michele; Knowles, Tuomas P. J.; Linse, Sara; Dobson, Christopher M.

    2014-01-01

    The formation of amyloid fibrils by the intrinsically disordered protein α-synuclein is a hallmark of Parkinson disease. To characterize the microscopic steps in the mechanism of aggregation of this protein we have used in vitro aggregation assays in the presence of preformed seed fibrils to determine the molecular rate constant of fibril elongation under a range of different conditions. We show that α-synuclein amyloid fibrils grow by monomer and not oligomer addition and are subject to higher-order assembly processes that decrease their capacity to grow. We also find that at neutral pH under quiescent conditions homogeneous primary nucleation and secondary processes, such as fragmentation and surface-assisted nucleation, which can lead to proliferation of the total number of aggregates, are undetectable. At pH values below 6, however, the rate of secondary nucleation increases dramatically, leading to a completely different balance between the nucleation and growth of aggregates. Thus, at mildly acidic pH values, such as those, for example, that are present in some intracellular locations, including endosomes and lysosomes, multiplication of aggregates is much faster than at normal physiological pH values, largely as a consequence of much more rapid secondary nucleation. These findings provide new insights into possible mechanisms of α-synuclein aggregation and aggregate spreading in the context of Parkinson disease. PMID:24817693

  9. Inverted initial conditions: Exploring the growth of cosmic structure and voids

    NASA Astrophysics Data System (ADS)

    Pontzen, Andrew; Slosar, Anže; Roth, Nina; Peiris, Hiranya V.

    2016-05-01

    We introduce and explore "paired" cosmological simulations. A pair consists of an A and B simulation with initial conditions related by the inversion δA(x ,tinitial)=-δB(x ,tinitial) (underdensities substituted for overdensities and vice versa). We argue that the technique is valuable for improving our understanding of cosmic structure formation. The A and B fields are by definition equally likely draws from Λ CDM initial conditions, and in the linear regime evolve identically up to the overall sign. As nonlinear evolution takes hold, a region that collapses to form a halo in simulation A will tend to expand to create a void in simulation B. Applications include (i) contrasting the growth of A-halos and B-voids to test excursion-set theories of structure formation, (ii) cross-correlating the density field of the A and B universes as a novel test for perturbation theory, and (iii) canceling error terms by averaging power spectra between the two boxes. Generalizations of the method to more elaborate field transformations are suggested.

  10. Inverted initial conditions: Exploring the growth of cosmic structure and voids

    DOE PAGESBeta

    Pontzen, Andrew; Roth, Nina; Peiris, Hiranya V.; Slosar, Anze

    2016-05-18

    We introduce and explore “paired” cosmological simulations. A pair consists of an A and B simulation with initial conditions related by the inversion δA(x,tinitial) = –δB(x,tinitial) (underdensities substituted for overdensities and vice versa). We argue that the technique is valuable for improving our understanding of cosmic structure formation. The A and B fields are by definition equally likely draws from ΛCDM initial conditions, and in the linear regime evolve identically up to the overall sign. As nonlinear evolution takes hold, a region that collapses to form a halo in simulation A will tend to expand to create a void inmore » simulation B. Applications include (i) contrasting the growth of A-halos and B-voids to test excursion-set theories of structure formation, (ii) cross-correlating the density field of the A and B universes as a novel test for perturbation theory, and (iii) canceling error terms by averaging power spectra between the two boxes. Furthermore, generalizations of the method to more elaborate field transformations are suggested.« less

  11. Device and method for screening crystallization conditions in solution crystal growth

    NASA Technical Reports Server (NTRS)

    Carter, Daniel C. (Inventor)

    1995-01-01

    A device and method for detecting optimum protein crystallization conditions and for growing protein crystals in either 1g or microgravity environments comprising a housing, defining at least one pair of chambers for containing crystallization solutions is presented. The housing further defines an orifice therein for providing fluid communication between the chambers. The orifice is adapted to receive a tube which contains a gelling substance for limiting the rate of diffusive mixing of the crystallization solutions. The solutions are diffusively mixed over a period of time defined by the quantity of gelling substance sufficient to achieve equilibration and to substantially reduce density driven convection disturbances therein. The device further includes endcaps to seal the first and second chambers. One of the endcaps includes a dialysis chamber which contains protein solution in which protein crystals are grown. Once the endcaps are in place, the protein solution is exposed to the crystallization solutions wherein the solubility of the protein solution is reduced at a rate responsive to the rate of diffusive mixing of the crystallization solutions. This allows for a controlled approach to supersaturation and allows for screening of crystal growth conditions at preselected intervals.

  12. Device and Method for Screening Crystallization Conditions in Solution Crystal Growth

    NASA Technical Reports Server (NTRS)

    Carter, Daniel C. (Inventor)

    1997-01-01

    A device and method for detecting optimum protein crystallization conditions and for growing protein crystals in either 1 g or microgravity environments comprising a housing defining at least one pair of chambers for containing crystallization solutions. The housing further defines an orifice therein for providing fluid communication between the chambers. The orifice is adapted to receive a tube which contains a gelling substance for limiting the rate of diffusive mixing of the crystallization solutions. The solutions are diffusively mixed over a period of time defined by the quantity of gelling substance sufficient to achieve equilibration and to substantially reduce density driven convection disturbances therein. The device further includes endcaps to seal the first and second chambers. One of the endcaps includes a dialysis chamber which contains protein solution in which protein crystals are grown. Once the endcaps are in place. the protein solution is exposed to the crystallization solutions wherein the solubility of the protein solution is reduced at a rate responsive to the rate of diffusive mixing of the crystallization solutions. This allows for a controlled approach to supersaturation and allows for screening of crystal growth conditions at preselected intervals.

  13. Generation of Mice With a Conditional Allele for the Transforming Growth Factor Beta3 Gene

    PubMed Central

    Doetschman, Thomas; Georgieva, Teodora; Li, Hongqi; Reed, Thomas D.; Grisham, Christina; Friel, Jacqueline; Estabrook, Mark A.; Gard, Connie; Sanford, L.P.; Azhar, Mohamad

    2013-01-01

    Summary The transforming growth factor beta (TGFβ) pathway is involved in embryonic development and several inherited and acquired human diseases. The gene for TGFβ3 (Tgfb3) encodes one of the three ligands for TGF b receptors. It is widely expressed in the embryo and its mutation or misexpression is found in human diseases. Tgfb3−/− mice die at birth from cleft palate, precluding functional studies in adults. Here, we generated mice in which exon 6 of Tgfb3 was flanked with LoxP sites (Tgfb3flox/flox). The adult mice were normal and fertile. EIIa-Cre-mediated deletion of exon 6 in Tgfb3flox/flox mice efficiently generated Tgfb3 conditional knockout (Tgfb3cko/cko) mice which died at birth from the same cleft palate defect as Tgfb3−/− mice, indicating that the conditional and knockout alleles are functionally equivalent. This Tgfb3cko allele will now enable studies of TGFβ3 function in different cell or tissue types in embryonic development and during adulthood. genesis 50:59-66, 2012. PMID:22223248

  14. Melt Convection Effects in the Bridgman Crystal Growth of an Alloy Under Microgravity Conditions

    NASA Technical Reports Server (NTRS)

    Simpson James E.; Garimella, Suresh V.; deGroh, Henry C., III; Abbaschian, Reza

    1998-01-01

    The solidification of a dilute bismuth-tin alloy under Bridgman crystal growth conditions is investigated in support of NASA's MEPHISTO space shuttle flight experiment. Computations are performed in two-dimensions with a uniform grid. The simulation includes the species-concentration, temperature and flow fields, as well as conduction in the ampoule. Fully transient simulations have been performed; no simplifying steady state approximations are used. Results are obtained under microgravity conditions for pure bismuth, and Bismuth-0.1 at.% Sn and Bi-1.0 at.% Sn alloys. The concentration dependence of the melting temperature is neglected; the solid/liquid interface temperature is assumed to be the melting temperature of pure bismuth for all cases studied. For the Bi-1.0 at.% Sn case the results indicate that a secondary convective cell, driven by solutal gradients, forms near the interface. The magnitude of the velocities in this cell increases with time; this causes increasing solute segregation at the liquid/solid interface.

  15. Optimum scratch assay condition to evaluate connective tissue growth factor expression for anti-scar therapy.

    PubMed

    Moon, Heekyung; Yong, Hyeyoung; Lee, Ae-Ri Cho

    2012-02-01

    To evaluate a potential anti-scar therapy, we first need to have a reliable in vitro wound model to understand dermal fibroblast response upon cell injury and how cytokine levels are changed upon different wound heal phases. An in vitro wound model with different scratch assay conditions on primary human foreskin fibroblast monolayer cultures was prepared and cytokine levels and growth properties were evaluated with the aim of determining optimum injury conditions and observation time. Morphological characteristics of differently scratched fibroblasts from 0 to 36 h post injury (1 line, 2 lines and 3 lines) were investigated. The expression of connective tissue growth factor, CTGF, which is a key mediator in hyper-tropic scarring, and relative intensity of CTGF as a function of time were determined by western blot and gelatin Zymography. After injury (1 line), CTGF level was increased more than 2-fold within 1 h and continuously increased up to 3-fold at 6 h and was leveled down to reach normal value at 36 h, at which cell migration was complete. In more serious injury (2 lines), higher expression of CTGF was observed. The down regulation of CTGF expression after CTGF siRNA/lipofectamine transfection in control, 1 line and 2 lines scratch conditions were 40%, 75% and 55%, respectively. As a model anti-CTGF based therapy, CTGF siRNA with different ratios of linear polyethyleneimine (PEI) complexes (1:1, 1:5, 1:10, 1:20 and 1:30) were prepared and down-regulation efficacy of CTGF was evaluated with our optimized scratch assay, which is 1 line injury at 6 h post injury observation time. As the cationic linear PEI ratio increased, the down regulation efficacy was increased from 20% (1:20) to 55% (1:30). As CTGF level was increased to the highest at 6 h and leveled down afterwards, CTGF level at 6 h could provide the most sensitive response upon CTGF siRNA transfection. The scratch assay in the present study can be employed as a useful experimental tool to differentiate

  16. Influence of initial growth conditions and Mg-surfactant on the quality of GaN film grown by MOVPE

    NASA Astrophysics Data System (ADS)

    Junsong, Cao; Xin, Lü; Lubing, Zhao; Shuang, Qu; Wei, Gao

    2015-02-01

    The initial growth conditions of a 100 nm thick GaN layer and Mg-surfactant on the quality of the GaN epilayer grown on a 6H-SiC substrate by metal-organic vapor phase epitaxy have been investigated in this research. Experimental results have shown that a high V/III ratio and the initially low growth rate of the GaN layer are favorable for two-dimension growth and surface morphology of GaN and the formation of a smoother growth surface. Mg-surfactant occurring during GaN growth can reduce the dislocations density of the GaN epilayer but increase the surface RMS, which are attributed to the change of growth mode.

  17. Are oysters being bored to death? Influence of Cliona celata on Crassostrea virginica condition, growth and survival.

    PubMed

    Carroll, John M; O'Shaughnessy, Kathryn A; Diedrich, Grant A; Finelli, Christopher M

    2015-11-17

    The boring sponge Cliona celata is a nuisance species that can have deleterious effects on eastern oyster Crassostrea virginica growth, condition, and survival. Surprisingly, however, these effects have not been well documented and when examined, results have been equi-vocal. In this study, we provide a direct comparison of growth, condition, and survival of sponge-colonized and uncolonized oysters in southeast North Carolina in 2 separate experiments. In the first experiment, sponge-colonized oysters exhibited significantly slower growth rates, reduced condition, and lower survival relative to uncolonized oysters, although results may have been confounded by oyster source. In the second experiment, using smaller oysters from the same source population, growth rate was again significantly reduced in colonized oysters relative to uncolonized oysters, however neither condition nor survival differed. In field surveys of the same population, colonized individuals across a range of sizes demonstrated significantly reduced condition. Further, condition index was negatively correlated with sponge biomass, which was positively correlated with oyster size, suggesting that the impact of the sponge changes with ontogeny. By investigating clearance rates, tissue isotopic and nutrient content, as well as caloric value, this study provides further evidence that sponge presence causes the oysters to divert energy into costly shell maintenance and repair at the expense of shell and somatic growth. Thus, although variable, our results demonstrate negative impacts of sponge infestation on oyster demographics, particularly as oysters grow larger. PMID:26575154

  18. Aerobic Denitrifying Bacteria That Produce Low Levels of Nitrous Oxide

    PubMed Central

    Takaya, Naoki; Catalan-Sakairi, Maria Antonina B.; Sakaguchi, Yasushi; Kato, Isao; Zhou, Zhemin; Shoun, Hirofumi

    2003-01-01

    Most denitrifiers produce nitrous oxide (N2O) instead of dinitrogen (N2) under aerobic conditions. We isolated and characterized novel aerobic denitrifiers that produce low levels of N2O under aerobic conditions. We monitored the denitrification activities of two of the isolates, strains TR2 and K50, in batch and continuous cultures. Both strains reduced nitrate (NO3−) to N2 at rates of 0.9 and 0.03 μmol min−1 unit of optical density at 540 nm−1 at dissolved oxygen (O2) (DO) concentrations of 39 and 38 μmol liter−1, respectively. At the same DO level, the typical denitrifier Pseudomonas stutzeri and the previously described aerobic denitrifier Paracoccus denitrificans did not produce N2 but evolved more than 10-fold more N2O than strains TR2 and K50 evolved. The isolates denitrified NO3− with concomitant consumption of O2. These results indicated that strains TR2 and K50 are aerobic denitrifiers. These two isolates were taxonomically placed in the β subclass of the class Proteobacteria and were identified as P. stutzeri TR2 and Pseudomonas sp. strain K50. These strains should be useful for future investigations of the mechanisms of denitrifying bacteria that regulate N2O emission, the single-stage process for nitrogen removal, and microbial N2O emission into th