Bio-energy conversion performance, biodegradability, and kinetic analysis of different fruit residues during discontinuous anaerobic digestion.

PubMed

Zhao, Chen; Yan, Hu; Liu, Yan; Huang, Yan; Zhang, Ruihong; Chen, Chang; Liu, Guangqing

2016-06-01

Huge amounts of fruit residues are produced and abandoned annually. The high moisture and organic contents of these residues makes them a big problem to the environment. Conversely, they are a potential resource to the world. Anaerobic digestion is a good way to utilize these organic wastes. In this study, the biomethane conversion performances of a large number of fruit residues were determined and compared using batch anaerobic digestion, a reliable and easily accessible method. The results showed that some fruit residues containing high contents of lipids and carbohydrates, such as loquat peels and rambutan seeds, were well fit for anaerobic digestion. Contrarily, residues with high lignin content were strongly recommended not to be used as a single substrate for methane production. Multiple linear regression model was adopted to simulate the correlation between the organic component of these fruit residues and their experimental methane yield, through which the experimental methane yield could probably be predicted for any other fruit residues. Four kinetic models were used to predict the batch anaerobic digestion process of different fruit residues. It was shown that the modified Gompertz and Cone models were better fit for the fruit residues compared to the first-order and Fitzhugh models. The first findings of this study could provide useful reference and guidance for future studies regarding the applications and potential utilization of fruit residues. Copyright © 2016 Elsevier Ltd. All rights reserved.

Monochloramine Cometabolism by Mixed-Culture Nitrifiers under Drinking Water Conditions

EPA Science Inventory

The current research investigated monochloramine cometabolism by nitrifying mixed cultures grown under drinking water relevant conditions and harvested from sand-packed reactors before conducting suspended growth batch kinetic experiments. Three batch reactors were used in each ...

Insight into metabolic and cometabolic activities of autotrophic and heterotrophic microorganisms in the biodegradation of emerging trace organic contaminants.

PubMed

Tran, Ngoc Han; Urase, Taro; Ngo, Huu Hao; Hu, Jiangyong; Ong, Say Leong

2013-10-01

Many efforts have been made to understand the biodegradation of emerging trace organic contaminants (EOCs) in the natural and engineered systems. This review summarizes the current knowledge on the biodegradation of EOCs while having in-depth discussion on metabolism and cometabolism of EOCs. Biodegradation of EOCs is mainly attributed to cometabolic activities of both heterotrophic and autotrophic microorganisms. Metabolism of EOCs can only be observed by heterotrophic microbes. Autotrophic ammonia oxidizing bacteria (AOB) and ammonia oxidizing archaeal (AOA) cometabolize a variety of EOCs via the non-specific enzymes, such as ammonia monooxygenase (AMO). Higher biodegradation of EOCs is often noted under nitrification at high ammonia loading rate. The presence of a growth substrate promotes cometabolic biodegradation of EOCs. Potential strategies for enhancing the biodegradation of EOCs were also proposed in this review. Copyright © 2013 Elsevier Ltd. All rights reserved.

Cometabolism of Monochloramine by Distribution System Relevant Mixed Culture Nitrifiers

EPA Science Inventory

Monochloramine (NH2Cl) is increasingly used as a residual disinfectant. A major problem related to NH2Cl is nitrification in distribution systems, leading to rapid NH2Cl residual loss. Ammonia-oxidizing bacteria (AOB), which oxidize ammonia (NH3) to nitrite, can cometabolize chem...

Cometabolism of Monochloramine by Nitrosomonas europaea under Distribution System Conditions

EPA Science Inventory

Batch kinetic experiments were carried out with a pure culture of N. europaea to characterize the kinetics of NH2Cl cometabolism. Nitrite, nitrate, NH2Cl, ammonia and pH were measured. The experiments were performed at a variety of conditions relevant to distribution system nitri...

Anaerobic Digestion.

PubMed

Liebetrau, Jan; Sträuber, Heike; Kretzschmar, Jörg; Denysenko, Velina; Nelles, Michael

2017-04-09

The term anaerobic digestion usually refers to the microbial conversion of organic material to biogas, which mainly consists of methane and carbon dioxide. The technical application of the naturally-occurring process is used to provide a renewable energy carrier and - as the substrate is often waste material - to reduce the organic matter content of the substrate prior to disposal.Applications can be found in sewage sludge treatment, the treatment of industrial and municipal solid wastes and wastewaters (including landfill gas utilization), and the conversion of agricultural residues and energy crops.For biorefinery concepts, the anaerobic digestion (AD) process is, on the one hand, an option to treat organic residues from other production processes. Concomitant effects are the reduction of organic carbon within the treated substance, the conversion of nitrogen and sulfur components, and the production of an energy-rich gas - the biogas. On the other hand, the multistep conversion of complex organic material offers the possibility of interrupting the conversion chain and locking out intermediates for utilization as basic material within the chemical industry.

COMETABOLISM OF TRIHALOMETHANES BY NITRIFYING BIOFILTERS UNDER DRINKING WATER TREATMENT PLANT CONDITIONS

EPA Science Inventory

EPA Identifier: FP916412
Title: Cometabolism of Trihalomethanes by Nitrifying Biofilters Under Drinking Water Treatment Plant Conditions
Fellow (Principal Investigator): David G. Wahman
Institution: University of Texas at Austin
EPA ...

Cometabolism of DDT analogs by a Pseudomonas sp.

PubMed Central

Francis, A J; Spanggord, R J; Ouchi, G I; Bohonos, N

1978-01-01

A Pseudomonas sp. capable of growth on several nonchlorinated and mono-p-chloro-substituted analogs of DDT as a sole carbon source degraded bis(p-chlorophenyl)methane and 1,1-bis(p-chlorophenyl)ethane only in the presence of diphenylethane. The products p-chlorophenylacetic acid and 2-(p-chlorophenyl)-propionic acid were not further metabolized by the bacterium. Other chlorinated analogs of DDT were found to be recalcitrant to cometabolic degradation with diphenylethane. PMID:637537

Aerobic biodegradation kinetics for 1,4-dioxane under metabolic and cometabolic conditions.

PubMed

Barajas-Rodriguez, Francisco J; Freedman, David L

2018-05-15

Biodegradation of 1,4-dioxane has been studied extensively, however, there is insufficient information on the kinetic characteristics of cometabolism by propanotrophs and a lack of systematic comparisons to metabolic biodegradation. To fill in these gaps, experiments were performed with suspended growth cultures to determine 16 Monod kinetic coefficients that describe metabolic consumption of 1,4-dioxane by Pseudonocardia dioxanivorans CB1190 and cometabolism by the propanotrophic mixed culture ENV487 and the propanotroph Rhodococcus ruber ENV425. Maximum specific growth rates were highest for ENV425, followed by ENV487 and CB1190. Half saturation constants for 1,4-dioxane for the propanotrophs were one-half to one-quarter those for CB1190. Propane was preferentially degraded over 1,4-dioxane, but the reverse did not occur. A kinetic model was used to simulate batch biodegradation of 1,4-dioxane. Propanotrophs decreased 1,4-dioxane from 1000 to 1 μg/L in less time than CB1190 when the initial biomass concentration was 0.74 mg COD/L; metabolic biodegradation was favored at higher initial biomass concentrations and higher initial 1,4-dioxane concentrations. 1,4-Dioxane biodegradation was inhibited when oxygen was below 1.5 mg/L. The kinetic model provides a framework for comparing in situ biodegradation of 1,4-dioxane via bioaugmentation with cultures that use the contaminant as a growth substrate to those that achieve biodegradation via cometabolism. Copyright © 2018 Elsevier B.V. All rights reserved.

Conversion of Cn-Unsaturated into Cn-2-Saturated LCFA Can Occur Uncoupled from Methanogenesis in Anaerobic Bioreactors.

PubMed

Cavaleiro, Ana J; Pereira, Maria Alcina; Guedes, Ana P; Stams, Alfons J M; Alves, M Madalena; Sousa, Diana Z

2016-03-15

Fat, oils, and grease present in complex wastewater can be readily converted to methane, but the energy potential of these compounds is not always recyclable, due to incomplete degradation of long chain fatty acids (LCFA) released during lipids hydrolysis. Oleate (C18:1) is generally the dominant LCFA in lipid-containing wastewater, and its conversion in anaerobic bioreactors results in palmitate (C16:0) accumulation. The reason why oleate is continuously converted to palmitate without further degradation via β-oxidation is still unknown. In this work, the influence of methanogenic activity in the initial conversion steps of unsaturated LCFA was studied in 10 bioreactors continuously operated with saturated or unsaturated C16- and C18-LCFA, in the presence or absence of the methanogenic inhibitor bromoethanesulfonate (BrES). Saturated Cn-2-LCFA accumulated both in the presence and absence of BrES during the degradation of unsaturated Cn-LCFA, and represented more than 50% of total LCFA. In the presence of BrES further conversion of saturated intermediates did not proceed, not even when prolonged batch incubation was applied. As the initial steps of unsaturated LCFA degradation proceed uncoupled from methanogenesis, accumulation of saturated LCFA can be expected. Analysis of the active microbial communities suggests a role for facultative anaerobic bacteria in the initial steps of unsaturated LCFA biodegradation. Understanding this role is now imperative to optimize methane production from LCFA.

Biological conversion of biogas to methanol using methanotrophs isolated from solid-state anaerobic digestate.

PubMed

Sheets, Johnathon P; Ge, Xumeng; Li, Yueh-Fen; Yu, Zhongtang; Li, Yebo

2016-02-01

The aim of this work was to isolate methanotrophs (methane oxidizing bacteria) that can directly convert biogas produced at a commercial anaerobic digestion (AD) facility to methanol. A methanotrophic bacterium was isolated from solid-state anaerobic digestate. The isolate had characteristics comparable to obligate methanotrophs from the genus Methylocaldum. This newly isolated methanotroph grew on biogas or purified CH4 and successfully converted biogas from AD to methanol. Methanol production was achieved using several methanol dehydrogenase (MDH) inhibitors and formate as an electron donor. The isolate also produced methanol using phosphate with no electron donor or using formate with no MDH inhibitor. The maximum methanol concentration (0.43±0.00gL(-1)) and 48-h CH4 to methanol conversion (25.5±1.1%) were achieved using biogas as substrate and a growth medium containing 50mM phosphate and 80mM formate. Copyright © 2015 Elsevier Ltd. All rights reserved.

Stable carbon isotope fractionation of trans-1,2-dichloroethylene during co-metabolic degradation by methanotrophic bacteria

USGS Publications Warehouse

Brungard, Karen L.; Munakata-Marr, Junko; Johnson, Craig A.; Mandernack, Kevin W.

2003-01-01

Changes in the carbon isotope ratio (δ13C) of trans-1,2-dichloroethylene (t-DCE) were measured during its co-metabolic degradation by Methylomonas methanica, a type I methanotroph, and Methylosinus trichosporium OB3b, a type II methanotroph. In closed-vessel incubation experiments with each bacterium, the residual t-DCE became progressively enriched in 13C, indicating isotopic fractionation. From these experiments, the biological fractionation during t-DCE co-metabolism, expressed as ε, was measured to be -3.50/00 for the type I culture and -6.70/00 for the type II culture. This fractionation effect and subsequent enrichment in the δ13C of the residual t-DCE can thus be applied to determine the extent of biodegradation of DCE by these organisms. Based on these results, isotopic fractionation clearly warrants further study, as measured changes in the δ13C values of chlorinated solvents could ultimately be used to monitor the extent of biodegradation in laboratory or field settings where co-metabolism by methanotrophs occurs.

Denitrifying sulfur conversion-associated EBPR: Effects of temperature and carbon source on anaerobic metabolism and performance.

PubMed

Guo, Gang; Wu, Di; Ekama, George A; Hao, Tianwei; Mackey, Hamish Robert; Chen, Guanghao

2018-04-16

The recently developed Denitrifying Sulfur conversion-associated Enhanced Biological Phosphorus Removal (DS-EBPR) process has demonstrated simultaneous removal of organics, nitrogen and phosphorus with minimal sludge production in the treatment of saline/brackish wastewater. Its performance, however, is sensitive to operating and environmental conditions. In this study, the effects of temperature (20, 25, 30 and 35 °C) and the ratio of influent acetate to propionate (100-0, 75-25, 50-50, 25-75 and 0-100%) on anaerobic metabolism were investigated, and their optimal values/controls for performance optimization were identified. A mature DS-EBPR sludge enriched with approximately 30% sulfate-reducing bacteria (SRB) and 33% sulfide-oxidizing bacteria (SOB) was used in this study. The anaerobic stoichiometry of this process was insensitive to temperature or changes in the carbon source. However, an increase in temperature from 20 to 35 °C accelerated the kinetic reactions of the functional bacteria (i.e. SRB and SOB) and raised the energy requirement for their anaerobic maintenance, while a moderate temperature (25-30 °C) resulted in better P removal (≥93%, 18.6 mg P/L removal from total 20 mg P/L in the influent) with a maximum sulfur conversion of approximately 16 mg S/L. These results indicate that the functional bacteria are likely to be mesophilic. When a mixed carbon source (75-25 and 50-50% acetate to propionate ratios) was supplied, DS-EBPR achieved a stable P removal (≥89%, 17.8 mg P/L for 400 mg COD/L in the influent) with sulfur conversions at around 23 mg S/L, suggesting the functional bacteria could effectively adapt to changes in acetate or propionate as the carbon source. The optimal temperatures or carbon source conditions maximized the functional bacteria competition against glycogen-accumulating organisms by favoring their activity and synergy. Therefore, the DS-EBPR process can be optimized by setting the temperature

Microbial Cometabolism and Polyhydroxyalkanoate Co-polymers.

PubMed

Ray, Subhasree; Kalia, Vipin Chandra

2017-03-01

Polyhydroxyalkanoate (PHAs) are natural, biodegradable biopolymers, which can be produced from renewable materials. PHAs have potential to replace petroleum derived plastics. Quite a few bacteria can produce PHA under nutritional stress. They generally produce homopolymers of butyrate i.e., polyhydroxybutyrate (PHB), as a storage material. The biochemical characteristics of PHB such as brittleness, low strength, low elasticity, etc. make these unsuitable for commercial applications. Co-polymers of PHA, have high commercial value as they overcome the limitations of PHBs. Co-polymers can be produced by supplementing the feed with volatile fatty acids or through hydrolysates of different biowastes. In this review, we have listed the potential bacterial candidates and the substrates, which can be co-metabolized to produce PHA co-polymers.

Reduction and conversion of 2,4,6-trinitrotoluene (TNT) by sulfide under simulated anaerobic conditions.

PubMed

Qiao, Hua; Wang, He-ling; Feng, Hua-jun; Yao, Jun; Shen, Dong-sheng; Tang, Zhi-jian

2010-07-15

To account for the fast disappearance of TNT in anaerobic fermentative liquid, we investigated TNT (TNT(0)=50 mg/L) reduction by Na(2)S at 30+/-1 degrees C in two types of buffer systems, a phosphate buffer (PB, system A) and a CH(3)COOH-NaHCO(3) buffer (system B). The effects of pH, sulfide concentration and buffer system on the conversion and reaction rate of TNT were investigated. The effect of different variables on the conversion of TNT decreased in the following order: Na(2)S concentration>pH>buffer system. A kinetics study showed that TNT reduction by Na(2)S occurred in two stages separated by a change point. The observed rate constants of the first stage K(obs-1) were 1 order of magnitude lower than those of the second stage. The TNT conversion rate increased and the time to reach the change point became shorter with increasing Na(2)S concentration and pH. A 5-fold increase in Na(2)S concentration above the theoretical stoichiometric concentration was optimum. Observed rate constants of the first stage K(obs-1) were proportional to the hydrosulfide ion concentration and the conversion rate of TNT was greater and faster in buffer system B than in system A. 2010 Elsevier B.V. All rights reserved.

Anaerobic Microbial Degradation of Hydrocarbons: From Enzymatic Reactions to the Environment.

PubMed

Rabus, Ralf; Boll, Matthias; Heider, Johann; Meckenstock, Rainer U; Buckel, Wolfgang; Einsle, Oliver; Ermler, Ulrich; Golding, Bernard T; Gunsalus, Robert P; Kroneck, Peter M H; Krüger, Martin; Lueders, Tillmann; Martins, Berta M; Musat, Florin; Richnow, Hans H; Schink, Bernhard; Seifert, Jana; Szaleniec, Maciej; Treude, Tina; Ullmann, G Matthias; Vogt, Carsten; von Bergen, Martin; Wilkes, Heinz

2016-01-01

Hydrocarbons are abundant in anoxic environments and pose biochemical challenges to their anaerobic degradation by microorganisms. Within the framework of the Priority Program 1319, investigations funded by the Deutsche Forschungsgemeinschaft on the anaerobic microbial degradation of hydrocarbons ranged from isolation and enrichment of hitherto unknown hydrocarbon-degrading anaerobic microorganisms, discovery of novel reactions, detailed studies of enzyme mechanisms and structures to process-oriented in situ studies. Selected highlights from this program are collected in this synopsis, with more detailed information provided by theme-focused reviews of the special topic issue on 'Anaerobic biodegradation of hydrocarbons' [this issue, pp. 1-244]. The interdisciplinary character of the program, involving microbiologists, biochemists, organic chemists and environmental scientists, is best exemplified by the studies on alkyl-/arylalkylsuccinate synthases. Here, research topics ranged from in-depth mechanistic studies of archetypical toluene-activating benzylsuccinate synthase, substrate-specific phylogenetic clustering of alkyl-/arylalkylsuccinate synthases (toluene plus xylenes, p-cymene, p-cresol, 2-methylnaphthalene, n-alkanes), stereochemical and co-metabolic insights into n-alkane-activating (methylalkyl)succinate synthases to the discovery of bacterial groups previously unknown to possess alkyl-/arylalkylsuccinate synthases by means of functional gene markers and in situ field studies enabled by state-of-the-art stable isotope probing and fractionation approaches. Other topics are Mo-cofactor-dependent dehydrogenases performing O2-independent hydroxylation of hydrocarbons and alkyl side chains (ethylbenzene, p-cymene, cholesterol, n-hexadecane), degradation of p-alkylated benzoates and toluenes, glycyl radical-bearing 4-hydroxyphenylacetate decarboxylase, novel types of carboxylation reactions (for acetophenone, acetone, and potentially also benzene and

Effect of toluene concentration and hydrogen peroxide on Pseudomonas plecoglossicida cometabolizing mixture of cis-DCE and TCE in soil slurry.

PubMed

Li, Junhui; Lu, Qihong; de Toledo, Renata Alves; Lu, Ying; Shim, Hojae

2015-12-01

An indigenous Pseudomonas sp., isolated from the regional contaminated soil and identified as P. plecoglossicida, was evaluated for its aerobic cometabolic removal of cis-1,2-dichloroethylene (cis-DCE) and trichloroethylene (TCE) using toluene as growth substrate in a laboratory-scale soil slurry. The aerobic simultaneous bioremoval of the cis-DCE/TCE/toluene mixture was studied under different conditions. Results showed that an increase in toluene concentration level from 300 to 900 mg/kg prolonged the lag phase for the bacterial growth, while the bioremoval extent for cis-DCE, TCE, and toluene declined as the initial toluene concentration increased. In addition, the cometabolic bioremoval of cis-DCE and TCE was inhibited by the presence of hydrogen peroxide as the additional oxygen source, while the bioremoval of toluene (900 mg/kg) was enhanced after 9 days of incubation. The subsequent addition of toluene did not improve the cometabolic bioremoval of cis-DCE and TCE. The obtained results would help to enhance the applicability of bioremediation technology to the mixed waste contaminated sites.

Enhanced cometabolic degradation of methyl tert-butyl ether by a Pseudomonas sp. strain grown on n-pentane

NASA Astrophysics Data System (ADS)

Li, S. S.; Wang, S.; Yan, W.

2016-08-01

When methyl tert-butyl ether (MTBE) is added as oxygenates it increases the octane number and decreases the release of nitric oxide from the incomplete combustion of reformulated gasoline. The extensive use of MTBE allowed it to be detectable as a pollutant in both ground-level and underground water worldwide. The present study focuses on the isolation and characterization of MTB-degrading microorganisms by cometabolism based on the results of growth on different carbon sources. It also focuses on the kinetic analysis and the continuous degradation of MTBE. A bacterial strain WL1 that can grow on both n-alkanes (C5-C8) and aromatics was isolated and named Pseudomonas sp. WL1 according to the 16S rDNA sequencing analysis. Strain WL1 could cometabolically degrade MTBE in the presence of n-alkanes with a desirable degradation rate. Diverse n-alkanes with different lengths of carbon chains showed significant influence on the degradation rate of MTBE and accumulation of tert-butyl alcohol (TBA). When strain WL1 cometabolically degraded MTBE in the presence of n-pentane, higher MTBE-degrading rate and lower TBA-accumulation were observed (Vmax = 38.1 nmol/min/mgprotei, Ks = 6.8 mmol/L). In the continuous degrading experiment, the removal efficiency of MTBE by Pseudomonas sp. WL1 did not show any obvious decrease after five subsequent additions.

Removal of pharmaceuticals and personal care products by ammonia oxidizing bacteria acclimated in a membrane bioreactor: Contributions of cometabolism and endogenous respiration.

PubMed

Park, Junwon; Yamashita, Naoyuki; Wu, Guangxue; Tanaka, Hiroaki

2017-12-15

We carried out batch experiments using biomass from a membrane bioreactor (MBR) to study the influence of ammonia oxidizing bacteria (AOB) on the removal of 45 pharmaceuticals and personal care products (PPCPs). Kinetic parameters such as biodegradation constants and adsorption coefficients with and without AOB inhibition were estimated. No significant differences in adsorption tendency were found, but the biodegradability of most compounds was enhanced when ammonia was completely oxidized, indicating that AOB present in MBR played a critical role in eliminating the PPCPs. Moreover, target PPCPs were degraded in 2 stages, first by cometabolic degradation related to AOB growth, and then by endogenous respiration by microorganisms in the absence of other growth substrate. The compounds were classified into 3 groups according to removal performance and cometabolic degradation. Our approach provides new insight into the removal of PPCPs via cometabolism and endogenous respiration under AOB enrichment cultures developed in MBR. Copyright © 2017 Elsevier B.V. All rights reserved.

CO2 fixation by anaerobic non-photosynthetic mixotrophy for improved carbon conversion.

PubMed

Jones, Shawn W; Fast, Alan G; Carlson, Ellinor D; Wiedel, Carrissa A; Au, Jennifer; Antoniewicz, Maciek R; Papoutsakis, Eleftherios T; Tracy, Bryan P

2016-09-30

Maximizing the conversion of biogenic carbon feedstocks into chemicals and fuels is essential for fermentation processes as feedstock costs and processing is commonly the greatest operating expense. Unfortunately, for most fermentations, over one-third of sugar carbon is lost to CO 2 due to the decarboxylation of pyruvate to acetyl-CoA and limitations in the reducing power of the bio-feedstock. Here we show that anaerobic, non-photosynthetic mixotrophy, defined as the concurrent utilization of organic (for example, sugars) and inorganic (for example, CO 2 ) substrates in a single organism, can overcome these constraints to increase product yields and reduce overall CO 2 emissions. As a proof-of-concept, Clostridium ljungdahlii was engineered to produce acetone and achieved a mass yield 138% of the previous theoretical maximum using a high cell density continuous fermentation process. In addition, when enough reductant (that is, H 2 ) is provided, the fermentation emits no CO 2 . Finally, we show that mixotrophy is a general trait among acetogens.

Cometabolic degradation of trichloroethene by Rhodococcus sp. strain L4 immobilized on plant materials rich in essential oils.

PubMed

Suttinun, Oramas; Müller, Rudolf; Luepromchai, Ekawan

2010-07-01

The cometabolic degradation of trichloroethene (TCE) by Rhodococcus sp. L4 was limited by the loss of enzyme activity during TCE transformation. This problem was overcome by repeated addition of inducing substrates, such as cumene, limonene, or cumin aldehyde, to the cells. Alternatively, Rhodococcus sp. L4 was immobilized on plant materials which contain those inducers in their essential oils. Cumin seeds were the most suitable immobilizing material, and the immobilized cells tolerated up to 68 muM TCE and degraded TCE continuously. The activity of immobilized cells, which had been inactivated partially during TCE degradation, could be reactivated by incubation in mineral salts medium without TCE. These findings demonstrate that immobilization of Rhodococcus sp. L4 on plant materials rich in essential oils is a promising method for efficient cometabolic degradation of TCE.

Versatile transformations of hydrocarbons in anaerobic bacteria: substrate ranges and regio- and stereo-chemistry of activation reactions†

PubMed Central

Jarling, René; Kühner, Simon; Basílio Janke, Eline; Gruner, Andrea; Drozdowska, Marta; Golding, Bernard T.; Rabus, Ralf; Wilkes, Heinz

2015-01-01

Anaerobic metabolism of hydrocarbons proceeds either via addition to fumarate or by hydroxylation in various microorganisms, e.g., sulfate-reducing or denitrifying bacteria, which are specialized in utilizing n-alkanes or alkylbenzenes as growth substrates. General pathways for carbon assimilation and energy gain have been elucidated for a limited number of possible substrates. In this work the metabolic activity of 11 bacterial strains during anaerobic growth with crude oil was investigated and compared with the metabolite patterns appearing during anaerobic growth with more than 40 different hydrocarbons supplied as binary mixtures. We show that the range of co-metabolically formed alkyl- and arylalkyl-succinates is much broader in n-alkane than in alkylbenzene utilizers. The structures and stereochemistry of these products are resolved. Furthermore, we demonstrate that anaerobic hydroxylation of alkylbenzenes does not only occur in denitrifiers but also in sulfate reducers. We propose that these processes play a role in detoxification under conditions of solvent stress. The thermophilic sulfate-reducing strain TD3 is shown to produce n-alkylsuccinates, which are suggested not to derive from terminal activation of n-alkanes, but rather to represent intermediates of a metabolic pathway short-cutting fumarate regeneration by reverse action of succinate synthase. The outcomes of this study provide a basis for geochemically tracing such processes in natural habitats and contribute to an improved understanding of microbial activity in hydrocarbon-rich anoxic environments. PMID:26441848

Simultaneous biodegradation of carbon tetrachloride and trichloroethylene in a coupled anaerobic/aerobic biobarrier.

PubMed

Kwon, Kiwook; Shim, Hojae; Bae, Wookeun; Oh, Juhyun; Bae, Jisu

2016-08-05

Simultaneous biodegradation of carbon tetrachloride (CT) and trichloroethylene (TCE) in a biobarrier with polyethylene glycol (PEG) carriers was studied. Toluene/methanol and hydrogen peroxide (H2O2) were used as electron donors and an electron acceptor source, respectively, in order to develop a biologically active zone. The average removal efficiencies for TCE and toluene were over 99.3%, leaving the respective residual concentrations of ∼12 and ∼57μg/L, which are below or close to the groundwater quality standards. The removal efficiency for CT was ∼98.1%, with its residual concentration (65.8μg/L) slightly over the standards. TCE was aerobically cometabolized with toluene as substrate while CT was anaerobically dechlorinated in the presence of electron donors, with the respective stoichiometric amount of chloride released. The oxygen supply at equivalent to 50% chemical oxygen demand of the injected electron donors supported successful toluene oxidation and also allowed local anaerobic environments for CT reduction. The originally augmented (immobilized in PEG carriers) aerobic microbes were gradually outcompeted in obtaining substrate and oxygen. Instead, newly developed biofilms originated from indigenous microbes in soil adapted to the coupled anaerobic/aerobic environment in the carrier for the simultaneous and almost complete removal of CT, TCE, and toluene. The declined removal rates when temperature fell from 28 to 18°C were recovered by doubling the retention time (7.2 days). Copyright © 2016 Elsevier B.V. All rights reserved.

Predicting yields for autotrophic and cometabolic processes

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

Andrews, G.

1995-12-31

The goal of bioprocess engineering is to state how the optimum design and control strategy for a bioprocess follow from the metabolism of the particular microorganism. A necessary step toward this goal is to show how the parameters used in quantitative descriptions of a process (e.g., yield and maintenance coefficients) are related to those describing the metabolism [e.g., Y{sub ATP}, (P/O)]. The {open_quotes}yield equation{close_quotes} approach to this problem involves dividing metabolism into the separate pathways for catabolism, anabolism, respiration, and product formation and balancing the production and consumption of reducing equivalents and ATP. The general approach, demonstrated previously for heterotrophicmore » cell growth and products of fermentation, is illustrated by three new examples: the cell yield for chemoautotrophic iron-oxidizing bacteria, the cometabolic degradation of chloroform by methanotrophic bacteria, and the theoretical yield of succinic acid from glucose.« less

Anaerobic bioprocessing of organic wastes.

PubMed

Verstraete, W; de Beer, D; Pena, M; Lettinga, G; Lens, P

1996-05-01

Anaerobic digestion of dissolved, suspended and solid organics has rapidly evolved in the last decades but nevertheless still faces several scientific unknowns. In this review, some fundamentals of bacterial conversions and adhesion are addressed initially. It is argued in the light of ΔG-values of reactions, and in view of the minimum energy quantum per mol, that anaerobic syntrophs must have special survival strategies in order to support their existence: redistributing the available energy between the partners, reduced end-product fermentation reactions and special cell-to-cell physiological interactions. In terms of kinetics, it appears that both reaction rates and residual substrate thresholds are strongly related to minimum ΔG-values. These new fundamental insights open perspectives for efficient design and operation of anaerobic bioprocesses. Subsequently, an overview is given of the current anaerobic biotechnology. For treating wastewaters, a novel and high performance new system has been introduced during the last decade; the upflow anaerobic sludge blanket system (UASB). This reactor concept requires anaerobic consortia to grow in a dense and eco-physiologically well-organized way. The microbial principles of such granular sludge growth are presented. Using a thermodynamic approach, the formation of different types of aggregates is explained. The application of this bioprocess in worldwide wastewater treatment is indicated. Due to the long retention times of the active biomass, the UASB is also suitable for the development of bacterial consortia capable of degrading xenobiotics. Operating granular sludge reactors at high upflow velocities (5-6 m/h) in expanded granular sludge bed (EGSB) systems enlarges the application field to very low strength wastewaters (chemical oxygen demand < 1 g/l) and psychrophilic temperatures (10°C). For the treatment of organic suspensions, there is currently a tendency to evolve from the conventional mesophilic

Anaerobic carbon monoxide metabolism by Pleomorphomonas carboxyditropha sp. nov., a new mesophilic hydrogenogenic carboxydotroph.

PubMed

Esquivel-Elizondo, Sofia; Maldonado, Juan; Krajmalnik-Brown, Rosa

2018-06-01

Carbon monoxide (CO)-metabolism and phenotypic and phylogenetic characterization of a novel anaerobic, mesophilic and hydrogenogenic carboxydotroph are reported. Strain SVCO-16 was isolated from anaerobic sludge and grows autotrophically and mixotrophically with CO. The genes cooS and cooF, coding for a CO dehydrogenase complex, and genes similar to hycE2, encoding a CO-induced hydrogenase, were present in its genome. The isolate produces H2 and CO2 from CO, and acetate and formate from organic substrates. Based on the 16S rRNA sequence, it is an Alphaproteobacterium most closely related to the genus Pleomorphomonas (98.9%-99.2% sequence identity). Comparison with other previously characterized Pleomorphomonas showed that P. diazotrophica and P. oryzae do not metabolize CO, and P. diazotrophica does not grow anaerobically with organic substrates. Average nucleotide identity values between strain SVCO-16 and P. diazotrophica, P. oryzae or P. koreensis were 86.66 ± 0.21%. These values are below the boundary to define species (95%-96%). Digital DNA-DNA hybridization estimates between strain SVCO-16 and reference strains were also below the 70% threshold for species delineation: 29.1%-34.5%. Based on the differences in CO metabolism, genome analyses and cellular fatty acid composition, the isolate should be classified into the genus Pleomorphomonas as a representative of a novel species, Pleomorphomonas carboxyditropha. The type strain of Pleomorphomonas carboxyditropha is SVCO-16T (strain deposit numbers, DSM 106132T and TSD-119T).

Cometabolic Degradation of Trichloroethene by Rhodococcus sp. Strain L4 Immobilized on Plant Materials Rich in Essential Oils▿ †

PubMed Central

Suttinun, Oramas; Müller, Rudolf; Luepromchai, Ekawan

2010-01-01

The cometabolic degradation of trichloroethene (TCE) by Rhodococcus sp. L4 was limited by the loss of enzyme activity during TCE transformation. This problem was overcome by repeated addition of inducing substrates, such as cumene, limonene, or cumin aldehyde, to the cells. Alternatively, Rhodococcus sp. L4 was immobilized on plant materials which contain those inducers in their essential oils. Cumin seeds were the most suitable immobilizing material, and the immobilized cells tolerated up to 68 μM TCE and degraded TCE continuously. The activity of immobilized cells, which had been inactivated partially during TCE degradation, could be reactivated by incubation in mineral salts medium without TCE. These findings demonstrate that immobilization of Rhodococcus sp. L4 on plant materials rich in essential oils is a promising method for efficient cometabolic degradation of TCE. PMID:20472723

Anaerobic digestion of cattail by rumen cultures.

PubMed

Hu, Zhen-Hu; Yu, Han-Qing

2006-01-01

The anaerobic digestion of aquatic plants could serve the dual roles for producing renewable energy and reducing waste. In this study, the anaerobic digestion of cattail (Typha latifolia linn), a lignocellulosic aquatic plant, by rumen microorganisms in batch cultures was investigated. At a substrate level of 12.4 g/l volatile solids (VS) and pH 6.7, maximum VS conversion of 66% was achieved within an incubation time of 125 h. However, a decrease in pH from 6.7 to 5.8 resulted in a marked reduction in VS conversion. The total volatile fatty acids (VFAs) yield was about 0.56 g/g VS digested. Acetate and propionate were the major aqueous fermentation products, while butyrate, i-butyrate and valerate were also formed in smaller quantities. Biogas that was produced was composed of carbon dioxide, methane and hydrogen. A modified Gompertz equation was developed to describe substrate consumption and product formation. The hydrolysis of insoluble components was the rate-limiting step in the anaerobic digestion of cattail.

Cometabolic biodegradation of trichloroethylene in microcosms

USGS Publications Warehouse

Kane, Allen C.; Wilson, Timothy P.; Fischer, Jeffrey M.

1997-01-01

Laboratory microcosms were used to determine the concentrations of oxygen (O2) and methane (CH4) that optimize trichloroethylene (TCE) biodegradation in sediment and ground-water samples from a TCE-contaminated aquifer at Picatinny Arsenal, Morris County, New Jersey. The mechanism for degradation is the cometabolic activity of methanotrophic bacteria. The laboratory data will be used to support a field study designed to demonstrate the effectiveness of combining air sparging with cometabolic degradation of TCE for the purpose of aquifer remediation. Microcosms were constructed in autoclaved 250-mL (milliliter) amber glass bottles with valves for repeated headspace sampling. Equal volumes (25 mL) of sediment and ground water, collected from a depth of 40 feet, were added. TCE was added to attain initial aqueous concentrations equal to the field level of 1,400 mu g/L (micrograms per liter). Nine microcosms were constructed with initial headspace O2 concentrations of 5%, 10%, or 14% and CH4 concentrations of 0.5%, 3%, or 5%, with nitrogen making up the balance. Sterile controls, controls without CH4, and controls without sediment were also constructed. A 4-mL gas sample was removed periodically and TCE, O2 , CH4 , and carbon dioxide (CO2) concentrations were measured by using gas chromatography. As biodegradation proceeded, the decrease in O2, CH4 , and TCE concentrations and the production of CO2 were monitored. An initial acclimation period of at least 100 days was observed in those microcosms in which significant microbial activity occurred, as determined from decreases in O2 and CH4 concentrations and an increase in CO2 content. Degradation of TCE occurred with O2 concentrations of 2.7 to 8.7% and CH4 concentrations of 0.5 to 3.5%. Microcosms that initially contained 10% O2 and 3% CH4 showed the greatest microbial activity and the greatest amount of TCE degradation. The greatest rates of TCE degradation occurred when O2 and CH4 headspace concentrations reached

Acclimation of aerobic-activated sludge degrading benzene derivatives and co-metabolic degradation activities of trichloroethylene by benzene derivative-grown aerobic sludge.

PubMed

Wang, Shizong; Yang, Qi; Bai, Zhiyong; Wang, Shidong; Wang, Yeyao; Nowak, Karolina M

2015-01-01

The acclimation of aerobic-activated sludge for degradation of benzene derivatives was investigated in batch experiments. Phenol, benzoic acid, toluene, aniline and chlorobenzene were concurrently added to five different bioreactors which contained the aerobic-activated sludge. After the acclimation process ended, the acclimated phenol-, benzoic acid-, toluene-, aniline- and chlorobenzene-grown aerobic-activated sludge were used to explore the co-metabolic degradation activities of trichloroethylene (TCE). Monod equation was employed to simulate the kinetics of co-metabolic degradation of TCE by benzene derivative-grown sludge. At the end of experiments, the mixed microbial communities grown under different conditions were identified. The results showed that the acclimation periods of microorganisms for different benzene derivatives varied. The maximum degradation rates of TCE for phenol-, benzoic acid-, toluene-, aniline- and chlorobenzene-grown aerobic sludge were 0.020, 0.017, 0.016, 0.0089 and 0.0047 mg g SS(-1) h(-1), respectively. The kinetic of TCE degradation in the absence of benzene derivative followed Monod equation well. Also, eight phyla were observed in the acclimated benzene derivative-grown aerobic sludge. Each of benzene derivative-grown aerobic sludge had different microbial community composition. This study can hopefully add new knowledge to the area of TCE co-metabolic by mixed microbial communities, and further the understanding on the function and applicability of aerobic-activated sludge.

The Co-Metabolism within the Gut-Brain Metabolic Interaction: Potential Targets for Drug Treatment and Design.

PubMed

Obrenovich, Mark; Flückiger, Rudolf; Sykes, Lorraine; Donskey, Curtis

2016-01-01

We know that within the complex mammalian gut is any number of metabolic biomes. The gut has been sometimes called the "second brain" within the "gut-brain axis". A more informative term would be the gut-brain metabolic interactome, which is coined here to underscore the relationship between the digestive system and cognitive function or dysfunction as the case may be. Co-metabolism between the host and the intestinal microbiota is essential for life's processes. How diet, lifestyle, antibiotics and other factors shape the gut microbiome constitutes a rapidly growing area of research. Conversely, the gut microbiome also affects mammalian systems. Metabolites of the gut-brain axis are potential targets for treatment and drug design since the interaction or biochemical interplay results in net metabolite production or end-products with either positive or negative effects on human health. This review explores the gut-brain metabolic interactome, with particular emphasis on drug design and treatment strategies and how commensal bacteria or their disruption lead to dysbiosis and the effect this has on neurochemistry. Increasing data indicate that the intestinal microbiome can affect neurobiology, from mental and even behavioral health to memory, depression, mood, anxiety, obesity, cravings and even the creation and maintenance of the blood brain barrier.

Anaerobes in Industrial- and Environmental Biotechnology.

PubMed

Hatti-Kaul, Rajni; Mattiasson, Bo

Anaerobic microorganisms present in diverse ecological niches employ alternative strategies for energy conservation in the absence of oxygen which enables them to play a key role in maintaining the global cycles of carbon, nitrogen, and sulfur, and the breakdown of persistent compounds. Thereby they become useful tools in industrial and environmental biotechnology. Although anaerobes have been relatively neglected in comparison to their aerobic counterparts, with increasing knowledge about their diversity and metabolic potential and the development of genetic tools and process technologies to utilize them, we now see a rapid expansion of their applications in the society. This chapter summarizes some of the developments in the use of anaerobes as tools for biomass valorization, in production of energy carriers and chemicals, wastewater treatment, and the strong potential in soil remediation. The ability of several autotrophic anaerobes to reduce carbon dioxide is attracting growing attention as a means for developing a platform for conversion of waste gases to chemicals, materials, and biofuels.

Toxic and inhibitory effects of trichloroethylene aerobic co-metabolism on phenol-grown aerobic granules.

PubMed

Zhang, Yi; Tay, JooHwa

2015-04-09

Aerobic granule, a form of microbial aggregate, exhibits good potential in degrading toxic and recalcitrant substances. In this study, the inhibitory and toxic effects of trichloroethylene (TCE), a model compound for aerobic co-metabolism, on phenol-grown aerobic granules were systematically studied, using respiratory activities after exposure to TCE as indicators. High TCE concentration did not exert positive or negative effects on the subsequent endogenous respiration rate or phenol dependent specific oxygen utilization rate (SOUR), indicating the absence of solvent stress and induction effect on phenol-hydroxylase. Phenol-grown aerobic granules exhibited a unique response to TCE transformation product toxicity, that small amount of TCE transformation enhanced the subsequent phenol SOUR. Granules that had transformed between 1.3 and 3.7 mg TCE gSS(-1) showed at most 53% increase in the subsequent phenol SOUR, and only when the transformation exceeded 6.6 mg TCE gSS(-1) did the SOUR dropped below that of the control. This enhancing effect was found to sustain throughout several phenol dosages, and TCE transformation below the toxicity threshold also lessened the granules' sensitivity to higher phenol concentration. The unique toxic effect was possibly caused by the granule's compact structure as a protection barrier against the diffusive transformation product(s) of TCE co-metabolism. Copyright © 2015 Elsevier B.V. All rights reserved.

Temporal variation selects for diet–microbe co-metabolic traits in the gut of Gorilla spp

PubMed Central

Gomez, Andres; Rothman, Jessica M; Petrzelkova, Klara; Yeoman, Carl J; Vlckova, Klara; Umaña, Juan D; Carr, Monica; Modry, David; Todd, Angelique; Torralba, Manolito; Nelson, Karen E; Stumpf, Rebecca M; Wilson, Brenda A; Blekhman, Ran; White, Bryan A; Leigh, Steven R

2016-01-01

Although the critical role that our gastrointestinal microbes play in host physiology is now well established, we know little about the factors that influenced the evolution of primate gut microbiomes. To further understand current gut microbiome configurations and diet–microbe co-metabolic fingerprints in primates, from an evolutionary perspective, we characterized fecal bacterial communities and metabolomic profiles in 228 fecal samples of lowland and mountain gorillas (G. g. gorilla and G. b. beringei, respectively), our closest evolutionary relatives after chimpanzees. Our results demonstrate that the gut microbiomes and metabolomes of these two species exhibit significantly different patterns. This is supported by increased abundance of metabolites and bacterial taxa associated with fiber metabolism in mountain gorillas, and enrichment of markers associated with simple sugar, lipid and sterol turnover in the lowland species. However, longitudinal sampling shows that both species' microbiomes and metabolomes converge when hosts face similar dietary constraints, associated with low fruit availability in their habitats. By showing differences and convergence of diet–microbe co-metabolic fingerprints in two geographically isolated primate species, under specific dietary stimuli, we suggest that dietary constraints triggered during their adaptive radiation were potential factors behind the species-specific microbiome patterns observed in primates today. PMID:26315972

In-Situ Anaerobic Biosurfactant Production Process For Remediation Of DNAPL Contamination In Subsurface Aquifers

NASA Astrophysics Data System (ADS)

Albino, J. D.; Nambi, I. M.

2009-12-01

microbial cultures. The microorganisms responsible for biosurfactant production was isolated and identified as Pseudomonas Sp (designated as Pseudomonas Sp ANBIOSURF-1, Gene bank no: FJ930079), Pseudomonas stutzeri (MTCC 10033), Pseudomonas Sp (MTCC 10032) from groundwater, soil and municipal sewage sludge enrichments respectively. This study confirms that biosurfactants can be produced under anaerobic conditions and also in sufficient quantities. The cultures were also able to cometabolically degrade PCE to Ethylene. The isolated microorganisms can be used for remediation of DNAPL contaminated sites by in-situ biosurfactant production.

Site-Specific Management of Miscanthus Genotypes for Combustion and Anaerobic Digestion: A Comparison of Energy Yields.

PubMed

Kiesel, Andreas; Nunn, Christopher; Iqbal, Yasir; Van der Weijde, Tim; Wagner, Moritz; Özgüven, Mensure; Tarakanov, Ivan; Kalinina, Olena; Trindade, Luisa M; Clifton-Brown, John; Lewandowski, Iris

2017-01-01

In Europe, the perennial C 4 grass miscanthus is currently mainly cultivated for energy generation via combustion. In recent years, anaerobic digestion has been identified as a promising alternative utilization pathway. Anaerobic digestion produces a higher-value intermediate (biogas), which can be upgraded to biomethane, stored in the existing natural gas infrastructure and further utilized as a transport fuel or in combined heat and power plants. However, the upgrading of the solid biomass into gaseous fuel leads to conversion-related energy losses, the level of which depends on the cultivation parameters genotype, location, and harvest date. Thus, site-specific crop management needs to be adapted to the intended utilization pathway. The objectives of this paper are to quantify (i) the impact of genotype, location and harvest date on energy yields of anaerobic digestion and combustion and (ii) the conversion losses of upgrading solid biomass into biogas. For this purpose, five miscanthus genotypes (OPM 3, 6, 9, 11, 14), three cultivation locations (Adana, Moscow, Stuttgart), and up to six harvest dates (August-March) were assessed. Anaerobic digestion yielded, on average, 35% less energy than combustion. Genotype, location, and harvest date all had significant impacts on the energy yield. For both, this is determined by dry matter yield and ash content and additionally by substrate-specific methane yield for anaerobic digestion and moisture content for combustion. Averaged over all locations and genotypes, an early harvest in August led to 25% and a late harvest to 45% conversion losses. However, each utilization option has its own optimal harvest date, determined by biomass yield, biomass quality, and cutting tolerance. By applying an autumn green harvest for anaerobic digestion and a delayed harvest for combustion, the conversion-related energy loss was reduced to an average of 18%. This clearly shows that the delayed harvest required to maintain biomass

Basewide Groundwater Operable Unit. Groundwater Operable Unit Remedial Investigation/Feasibility Study Report. Volume 3

DTIC Science & Technology

1994-06-01

technologies were organized into five categories: * In Situ Biological Treatment * In Situ Physical/Chemical Treatment * Ex Situ Biological Groundwater...Technology FIGURE 11-3 PRIMARY SCORING SUMMARY EX SITU BIOLOGICAL GROUNDWATER TREATMENT TECHNOLOGIES GROUNDWATER OPERABLE UNIT RIIFS McCLELLAN AIR FORCE... Biological Treatment CometabolicAnaerobic Anaerobic/Aerobic In Situ Physical/Chemical Treatment Sparging/Soil Vapor Extraction Ex Situ Biological

Distribution of sulfonamides in liquid and solid anaerobic digestates: effects of hydraulic retention time and swine manure to rice straw ratio.

PubMed

Jin, Hongmei; Xu, Caiyun; Du, Jing; Wu, Huashan; Huang, Hongying; Chang, Zhizhou; Xu, Yueding; Zhou, Lixiang

2017-02-01

The effects of hydraulic retention time (20 and 15 days) and swine manure to rice straw ratios on distribution of sulfonamides (SAs) in liquid and solid anaerobic digestates were studied using bench-scale completely stirred tank reactors at (37 ± 1) °C. Results showed that anaerobic digestion (AD) treatment exhibited a good removal effect on sulfadiazine (SDZ), sulfadimidine (SM2) and sulfachloropyridazine (SCP), especially at HRT = 20 days and co-digestion with swine manure and rice straw. The removal rates of SDZ and SM2 were more than 90%, but only 72.8% for SCP. The residual SAs were mainly remained in solid digestates, with residual rates ranging from 28.8% to 71.3%, 40.6% to 88.0, and 82.7% to 97.0% for SDZ, SM2 and SCP, respectively. Due to lower pKa and higher log K ow of SCP, its residue in solid digestates was far more than SDZ and SM2. Higher HRT and co-digestion could improve the degradation of SAs, which can also be put down to the occurrence of cometabolism of SAs and COD.

Optimization of semi-continuous anaerobic digestion of sugarcane straw co-digested with filter cake: Effects of macronutrients supplementation on conversion kinetics.

PubMed

Janke, Leandro; Weinrich, Sören; Leite, Athaydes F; Schüch, Andrea; Nikolausz, Marcell; Nelles, Michael; Stinner, Walter

2017-12-01

Anaerobic digestion of sugarcane straw co-digested with sugarcane filter cake was investigated with a special focus on macronutrients supplementation for an optimized conversion process. Experimental data from batch tests and a semi-continuous experiment operated in different supplementation phases were used for modeling the conversion kinetics based on continuous stirred-tank reactors. The semi-continuous experiment showed an overall decrease in the performance along the inoculum washout from the reactors. By supplementing nitrogen alone or in combination to phosphorus and sulfur the specific methane production significantly increased (P<0.05) by 17% and 44%, respectively. Although the two-pool one-step model has fitted well to the batch experimental data (R 2 >0.99), the use of the depicted kinetics did not provide a good estimation for process simulation of the semi-continuous process (in any supplementation phase), possibly due to the different feeding modes and inoculum source, activity and adaptation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Expression of an alkane monooxygenase (alkB) gene and methyl tert-butyl ether co-metabolic oxidation in Pseudomonas citronellolis.

PubMed

Bravo, Ana Luisa; Sigala, Juan Carlos; Le Borgne, Sylvie; Morales, Marcia

2015-04-01

Pseudomonas citronellolis UAM-Ps1 co-metabolically transforms methyl tert-butyl ether (MTBE) to tert-butyl alcohol with n-pentane (2.6 mM), n-octane (1.5 mM) or dicyclopropylketone (DCPK) (4.4 mM), a gratuitous inducer of alkane hydroxylase (AlkB) activity. The reverse transcription quantitative real-time PCR was used to quantify the alkane monooxygenase (alkB) gene expression. The alkB gene was expressed in the presence of n-alkanes and DCPK and MTBE oxidation occurred only in cultures when alkB was transcribed. A correlation between the number of alkB transcripts and MTBE consumption was found (ΜΤΒΕ consumption in μmol = 1.44e(-13) x DNA copies, R(2) = 0.99) when MTBE (0.84 mM) was added. Furthermore, alkB was cloned and expressed into Escherichia coli and the recombinant AlkB had a molecular weight of 42 kDa. This is the first report where the expression of alkB is related to the co-metabolic oxidation of MTBE.

A modeling approach to describe ZVI-based anaerobic system.

PubMed

Xiao, Xiao; Sheng, Guo-Ping; Mu, Yang; Yu, Han-Qing

2013-10-15

Zero-valent iron (ZVI) is increasingly being added into anaerobic reactors to enhance the biological conversion of various less biodegradable pollutants (LBPs). Our study aimed to establish a new structure model based on the Anaerobic Digestion Model No. 1 (ADM1) to simulate such a ZVI-based anaerobic reactor. Three new processes, i.e., electron release from ZVI corrosion, H2 formation from ZVI corrosion, and transformation of LBPs, were integrated into ADM1. The established model was calibrated and tested using the experimental data from one published study, and validated using the data from another work. A good relationship between the predicted and measured results indicates that the proposed model was appropriate to describe the performance of the ZVI-based anaerobic system. Our model could provide more precise strategies for the design, development, and application of anaerobic systems especially for treating various LBPs-containing wastewaters. Copyright © 2013 Elsevier Ltd. All rights reserved.

Kinetics of trichloroethylene cometabolism and toluene biodegradation: Model application to soil batch experiments

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

El-Farhan, Y.H.; Scow, K.M.; Fan, S.

Trichloroethylene (TCE) biodegradation in soil under aerobic conditions requires the presence of another compound, such as toluene, to support growth of microbial populations and enzyme induction. The biodegradation kinetics of TCE and toluene were examined by conducting three groups of experiments in soil: toluene only, toluene combined with low TCE concentrations, and toluene with TCE concentrations similar to or higher than toluene. The biodegradation of TCE and toluene and their interrelationships were modeled using a combination of several biodegradation functions. In the model, the pollutants were described as existing in the solid, liquid, and gas phases of soil, with biodegradationmore » occurring only in the liquid phase. The distribution of the chemicals between the solid and liquid phase was described by a linear sorption isotherm, whereas liquid-vapor partitioning was described by Henry's law. Results from 12 experiments with toluene only could be described by a single set of kinetic parameters. The same set of parameters could describe toluene degradation in 10 experiments where low TCE concentrations were present. From these 10 experiments a set of parameters describing TCE cometabolism induced by toluene also was obtained. The complete set of parameters was used to describe the biodegradation of both compounds in 15 additional experiments, where significant TCE toxicity and inhibition effects were expected. Toluene parameters were similar to values reported for pure culture systems. Parameters describing the interaction of TCE with toluene and biomass were different from reported values for pure cultures, suggesting that the presence of soil may have affected the cometabolic ability of the indigenous soil microbial populations.« less

Co-Metabolic Degradation of β-Cypermethrin and 3-Phenoxybenzoic Acid by Co-Culture of Bacillus licheniformis B-1 and Aspergillus oryzae M-4.

PubMed

Zhao, Jiayuan; Chi, Yuanlong; Xu, Yingchao; Jia, Dongying; Yao, Kai

2016-01-01

The degradation efficiency of organic contaminants and their associated metabolites by co-culture of microbes is mainly limited by toxic intermediates from co-metabolic degradation. In this study, we investigated the degradation of β-cypermethrin (β-CY) and 3-phenoxybenzoic acid (3-PBA) by co-culture of Bacillus licheniformis B-1 and Aspergillus oryzae M-4, as well as the influences of β-CY and 3-PBA metabolites on their degradation and the growth of strains B-1 and M-4. Our results indicated that 100 mg/L β-CY was degraded by 78.85%, and 3-PBA concentration was 0.05 mg/L after 72 h. Compared with using only strain B-1, the half-life (t1/2) of β-CY by using the two strains together was shortened from 84.53 h to 38.54 h, and the yield coefficient of 3-PBA was decreased from 0.846 to 0.001. At 100 mg/L of 3-PBA and gallic acid, β-CY and 3-PBA degradation were only 17.68% and 40.45%, respectively. As the toxic intermediate derived from co-metabolic degradation of β-CY by strain B-1, 3-PBA was efficiently degraded by strain M-4, and gallic acid, as the toxic intermediate from co-metabolic degradation of 3-PBA by strain M-4, was efficiently degraded by strain B-1. These results provided a promising approach for efficient biodegradation of β-CY and 3-PBA.

Site-Specific Management of Miscanthus Genotypes for Combustion and Anaerobic Digestion: A Comparison of Energy Yields

PubMed Central

Kiesel, Andreas; Nunn, Christopher; Iqbal, Yasir; Van der Weijde, Tim; Wagner, Moritz; Özgüven, Mensure; Tarakanov, Ivan; Kalinina, Olena; Trindade, Luisa M.; Clifton-Brown, John; Lewandowski, Iris

2017-01-01

In Europe, the perennial C4 grass miscanthus is currently mainly cultivated for energy generation via combustion. In recent years, anaerobic digestion has been identified as a promising alternative utilization pathway. Anaerobic digestion produces a higher-value intermediate (biogas), which can be upgraded to biomethane, stored in the existing natural gas infrastructure and further utilized as a transport fuel or in combined heat and power plants. However, the upgrading of the solid biomass into gaseous fuel leads to conversion-related energy losses, the level of which depends on the cultivation parameters genotype, location, and harvest date. Thus, site-specific crop management needs to be adapted to the intended utilization pathway. The objectives of this paper are to quantify (i) the impact of genotype, location and harvest date on energy yields of anaerobic digestion and combustion and (ii) the conversion losses of upgrading solid biomass into biogas. For this purpose, five miscanthus genotypes (OPM 3, 6, 9, 11, 14), three cultivation locations (Adana, Moscow, Stuttgart), and up to six harvest dates (August–March) were assessed. Anaerobic digestion yielded, on average, 35% less energy than combustion. Genotype, location, and harvest date all had significant impacts on the energy yield. For both, this is determined by dry matter yield and ash content and additionally by substrate-specific methane yield for anaerobic digestion and moisture content for combustion. Averaged over all locations and genotypes, an early harvest in August led to 25% and a late harvest to 45% conversion losses. However, each utilization option has its own optimal harvest date, determined by biomass yield, biomass quality, and cutting tolerance. By applying an autumn green harvest for anaerobic digestion and a delayed harvest for combustion, the conversion-related energy loss was reduced to an average of 18%. This clearly shows that the delayed harvest required to maintain biomass

Anaerobic digestion as a waste disposal option for American Samoa

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

Rivard, C

1993-01-01

Tuna sludge and municipal solid waste (MSW) generated on Tutuila Island, American Samoa, represent an ongoing disposal problem as well as an emerging opportunity for use in renewable fuel production. This research project focuses on the biological conversion of the organic fraction of these wastes to useful products including methane and fertilizer-grade residue through anaerobic high solids digestion. In this preliminary study, the anaerobic bioconversion of tuna sludge with MSW appears promising.

Biomass conversion processes for energy and fuels

NASA Astrophysics Data System (ADS)

Sofer, S. S.; Zaborsky, O. R.

The book treats biomass sources, promising processes for the conversion of biomass into energy and fuels, and the technical and economic considerations in biomass conversion. Sources of biomass examined include crop residues and municipal, animal and industrial wastes, agricultural and forestry residues, aquatic biomass, marine biomass and silvicultural energy farms. Processes for biomass energy and fuel conversion by direct combustion (the Andco-Torrax system), thermochemical conversion (flash pyrolysis, carboxylolysis, pyrolysis, Purox process, gasification and syngas recycling) and biochemical conversion (anaerobic digestion, methanogenesis and ethanol fermentation) are discussed, and mass and energy balances are presented for each system.

Microbial degradation of chloroethenes: a review.

PubMed

Dolinová, Iva; Štrojsová, Martina; Černík, Miroslav; Němeček, Jan; Macháčková, Jiřina; Ševců, Alena

2017-05-01

Contamination by chloroethenes has a severe negative effect on both the environment and human health. This has prompted intensive remediation activity in recent years, along with research into the efficacy of natural microbial communities for degrading toxic chloroethenes into less harmful compounds. Microbial degradation of chloroethenes can take place either through anaerobic organohalide respiration, where chloroethenes serve as electron acceptors; anaerobic and aerobic metabolic degradation, where chloroethenes are used as electron donors; or anaerobic and aerobic co-metabolic degradation, with chloroethene degradation occurring as a by-product during microbial metabolism of other growth substrates, without energy or carbon benefit. Recent research has focused on optimising these natural processes to serve as effective bioremediation technologies, with particular emphasis on (a) the diversity and role of bacterial groups involved in dechlorination microbial processes, and (b) detection of bacterial enzymes and genes connected with dehalogenation activity. In this review, we summarise the different mechanisms of chloroethene bacterial degradation suitable for bioremediation and provide a list of dechlorinating bacteria. We also provide an up-to-date summary of primers available for detecting functional genes in anaerobic and aerobic bacteria degrading chloroethenes metabolically or co-metabolically.

Insights into plant biomass conversion from the genome of the anaerobic thermophilic bacterium Caldicellulosiruptor bescii DSM 6725

PubMed Central

Dam, Phuongan; Kataeva, Irina; Yang, Sung-Jae; Zhou, Fengfeng; Yin, Yanbin; Chou, Wenchi; Poole, Farris L.; Westpheling, Janet; Hettich, Robert; Giannone, Richard; Lewis, Derrick L.; Kelly, Robert; Gilbert, Harry J.; Henrissat, Bernard; Xu, Ying; Adams, Michael W. W.

2011-01-01

Caldicellulosiruptor bescii DSM 6725 utilizes various polysaccharides and grows efficiently on untreated high-lignin grasses and hardwood at an optimum temperature of ∼80°C. It is a promising anaerobic bacterium for studying high-temperature biomass conversion. Its genome contains 2666 protein-coding sequences organized into 1209 operons. Expression of 2196 genes (83%) was confirmed experimentally. At least 322 genes appear to have been obtained by lateral gene transfer (LGT). Putative functions were assigned to 364 conserved/hypothetical protein (C/HP) genes. The genome contains 171 and 88 genes related to carbohydrate transport and utilization, respectively. Growth on cellulose led to the up-regulation of 32 carbohydrate-active (CAZy), 61 sugar transport, 25 transcription factor and 234 C/HP genes. Some C/HPs were overproduced on cellulose or xylan, suggesting their involvement in polysaccharide conversion. A unique feature of the genome is enrichment with genes encoding multi-modular, multi-functional CAZy proteins organized into one large cluster, the products of which are proposed to act synergistically on different components of plant cell walls and to aid the ability of C. bescii to convert plant biomass. The high duplication of CAZy domains coupled with the ability to acquire foreign genes by LGT may have allowed the bacterium to rapidly adapt to changing plant biomass-rich environments. PMID:21227922

Microcosm Studies to Evaluate Aerobic Cometabolism of Low Concentrations of 1,4-Dioxane by Isobutane-utilizing Microorganisms in the Presence of Chlorinated Solvent Co-contaminants

NASA Astrophysics Data System (ADS)

Rolston, H. M.; Azizian, M.; Hyman, M. R.; Semprini, L.

2015-12-01

Due to its use as a stabilizer for chlorinated solvents, 1,4-dioxane (1,4D), a probable human carcinogen, is a common co-contaminant in solvent spills at industrial and military sites and landfills. Its persistence in large groundwater plumes at low concentrations makes it a relevant candidate for in-situ bioremediation via cometabolism. Microcosm studies are being performed to evaluate the capability of aerobic microorganisms to cometabolize mixtures of 1,4D and chlorinated solvents, such as trichloroethylene (TCE), 1,1,1-trichloroethane (1,1,1TCA), and 1,1-dichloroethene (1,1DCE), with isobutane as the primary substrate. Microcosms were constructed using aquifer solids from Fort Carson, Colorado, a site contaminated with 1,4D and TCE, to assess the isobutane uptake and transformation of 1,4D and chlorinated solvents by microorganisms native to the site. Additional microcosms were augmented with Rhodococcus rhodochrous, a bacterium shown to cometabolize 1,4D and chlorinated solvents. Results indicate that native microcosms cometabolized 1,4D upon stimulation with isobutane after a lag period of about 15 days. TCE was also transformed, but at significantly slower rates. The presence of 1,4D and TCE at 500 and 300 ppb, respectively, did not inhibit the growth of native microorganisms on isobutane, with isobutane uptake and 1,4D transformation occurring simultaneously. Bioaugmented microcosms transformed 1,4D immediately after inoculation with R. rhodochrous. Tests in bioaugmented microorganisms indicated that the presence of TCE at low concentrations inhibits but does not block the transformation of 1,4D. Results from the microcosms will be used to design field tests to be performed at Fort Carson. Additional microcosm studies will compare the stimulation of native and bioaugmented microcosms and the transformation of mixtures of 1,4D, 1,1,1TCA and 1,1DCE. Molecular methods will analyze the monoxygenase enzymes expressed in the native and bioaugmented microcosms.

Effect of substrate and cation requirement on anaerobic volatile fatty acid conversion rates at elevated biogas pressure.

PubMed

Lindeboom, Ralph E F; Ferrer, Ivet; Weijma, Jan; van Lier, Jules B

2013-12-01

This work studied the anaerobic conversion of neutralized volatile fatty acids (VFA) into biogas under Autogenerative High Pressure Digestion (AHPD) conditions. The effects of the operating conditions on the biogas quality, and the substrate utilisation rates were evaluated using 3 AHPD reactors (0.6 L); feeding a concentration of acetate and VFA (1-10 g COD/L) corresponding to an expected pressure increase of 1-20 bar. The biogas composition improved with pressure up to 4.5 bar (>93% CH4), and stabilized at 10 and 20 bar. Both, acetotrophic and hydrogenotrophic methanogenic activity was observed. Substrate utilisation rates of 0.2, 0.1 and 0.1 g CODCH4/g VSS/d for acetate, propionate and butyrate were found to decrease by up to 50% with increasing final pressure. Most likely increased Na(+)-requirement to achieve CO2 sequestration at higher pressure rather than end-product inhibition was responsible. Copyright © 2013 Elsevier Ltd. All rights reserved.

Effects of gasoline components on MTBE and TBA cometabolism by Mycobacterium austroafricanum JOB5.

PubMed

House, Alan J; Hyman, Michael R

2010-07-01

In this study we have examined the effects of individual gasoline hydrocarbons (C(5-10,12,14) n-alkanes, C(5-8) isoalkanes, alicyclics [cyclopentane and methylcyclopentane] and BTEX compounds [benzene, toluene, ethylbenzene, m-, o-, and p-xylene]) on cometabolism of methyl tertiary butyl ether (MTBE) and tertiary butyl alcohol (TBA) by Mycobacterium austroafricanum JOB5. All of the alkanes tested supported growth and both MTBE and TBA oxidation. Growth on C(5-8) n-alkanes and isoalkanes was inhibited by acetylene whereas growth on longer chain n-alkanes was largely unaffected by this gas. However, oxidation of both MTBE and TBA by resting cells was consistently inhibited by acetylene, irrespective of the alkane used as growth-supporting substrate. A model involving two separate but co-expressed alkane-oxidizing enzyme systems is proposed to account for these observations. Cyclopentane, methylcyclopentane, benzene and ethylbenzene did not support growth but these compounds all inhibited MTBE and TBA oxidation by alkane-grown cells. In the case of benzene, the inhibition was shown to be due to competitive interactions with both MTBE and TBA. Several aromatic compounds (p-xylene > toluene > m-xylene) did support growth and cells previously grown on these substrates also oxidized MTBE and TBA. Low concentrations of toluene (<10 microM) stimulated MTBE and TBA oxidation by alkane-grown cells whereas higher concentrations were inhibitory. The effects of acetylene suggest strain JOB5 also has two distinct toluene-oxidizing activities. These results have been discussed in terms of their impact on our understanding of MTBE and TBA cometabolism and the enzymes involved in these processes in mycobacteria and other bacteria.

Anaerobic Benzene Oxidation via Phenol in Geobacter metallireducens

PubMed Central

Tremblay, Pier-Luc; Chaurasia, Akhilesh Kumar; Smith, Jessica A.; Bain, Timothy S.; Lovley, Derek R.

2013-01-01

Anaerobic activation of benzene is expected to represent a novel biochemistry of environmental significance. Therefore, benzene metabolism was investigated in Geobacter metallireducens, the only genetically tractable organism known to anaerobically degrade benzene. Trace amounts (<0.5 μM) of phenol accumulated in cultures of Geobacter metallireducens anaerobically oxidizing benzene to carbon dioxide with the reduction of Fe(III). Phenol was not detected in cell-free controls or in Fe(II)- and benzene-containing cultures of Geobacter sulfurreducens, a Geobacter species that cannot metabolize benzene. The phenol produced in G. metallireducens cultures was labeled with 18O during growth in H218O, as expected for anaerobic conversion of benzene to phenol. Analysis of whole-genome gene expression patterns indicated that genes for phenol metabolism were upregulated during growth on benzene but that genes for benzoate or toluene metabolism were not, further suggesting that phenol was an intermediate in benzene metabolism. Deletion of the genes for PpsA or PpcB, subunits of two enzymes specifically required for the metabolism of phenol, removed the capacity for benzene metabolism. These results demonstrate that benzene hydroxylation to phenol is an alternative to carboxylation for anaerobic benzene activation and suggest that this may be an important metabolic route for benzene removal in petroleum-contaminated groundwaters, in which Geobacter species are considered to play an important role in anaerobic benzene degradation. PMID:24096430

A comprehensive review on food waste anaerobic digestion: Research updates and tendencies.

PubMed

Ren, Yuanyuan; Yu, Miao; Wu, Chuanfu; Wang, Qunhui; Gao, Ming; Huang, Qiqi; Liu, Yu

2018-01-01

Anaerobic digestion has been practically applied in agricultural and industrial waste treatment and recognized as an economical-effective way for food waste disposal. This paper presented an overview on the researches about anaerobic digestion of food waste. Technologies (e.g., pretreatment, co-digestion, inhibition and mitigation, anaerobic digestion systems, etc.) were introduced and evaluated on the basis of bibliometric analysis. Results indicated that ethanol and aerobic prefermentation were novel approaches to enhance substrates hydrolysis and methane yield. With the promotion of resource recovery, more attention should be paid to biorefinery technologies which can produce more useful products toward zero emissions. Furthermore, a technological route for food waste conversion based on anaerobic digestion was proposed. Copyright © 2017 Elsevier Ltd. All rights reserved.

Exposure to polystyrene nanoplastic leads to inhibition of anaerobic digestion system.

PubMed

Fu, Shan-Fei; Ding, Jian-Nan; Zhang, Yun; Li, Yi-Fei; Zhu, Rong; Yuan, Xian-Zheng; Zou, Hua

2018-06-01

In this study, impacts of nanoplastic on the pure and mixed anaerobic digestion systems were investigated. Results showed the growth and metabolism of Acetobacteroides hydrogenigenes were partly inhibited by nanoplastic existed in the pure anaerobic digestion system. The anaerobic digestion of sewage sludge was also obviously inhibited by nanoplastic existed in the mixed anaerobic digestion system. Both the methane yield and methane production rate of the mixed anaerobic digestion system showed negative correlation with the nanoplastic concentration. Compared with anaerobic digestion system without nanoplastic, methane yield and maximum daily methane yield at the nanoplastic concentration of 0.2g/L decreased for 14.4% and 40.7%, respectively. In addition, the start-up of mixed anaerobic digestion system was prolonged by addition of nanoplastic. Microbial community structure analysis indicated the microbial community structures were also affected by nanoplastic existed in the system. At the nanoplastic concentration of 0.2g/L, the relative abundances of family Cloacamonaceae, Porphyromonadaceae, Anaerolinaceae and Gracilibacteraceae decreased partly. Conversely, the relative abundances of family Anaerolinaceae, Clostridiaceae, Geobacteraceae, Dethiosulfovibrionaceae and Desulfobulbaceae improved partly. Copyright © 2017 Elsevier B.V. All rights reserved.

Early anaerobic metabolisms

PubMed Central

Canfield, Don E; Rosing, Minik T; Bjerrum, Christian

2006-01-01

Before the advent of oxygenic photosynthesis, the biosphere was driven by anaerobic metabolisms. We catalogue and quantify the source strengths of the most probable electron donors and electron acceptors that would have been available to fuel early-Earth ecosystems. The most active ecosystems were probably driven by the cycling of H2 and Fe2+ through primary production conducted by anoxygenic phototrophs. Interesting and dynamic ecosystems would have also been driven by the microbial cycling of sulphur and nitrogen species, but their activity levels were probably not so great. Despite the diversity of potential early ecosystems, rates of primary production in the early-Earth anaerobic biosphere were probably well below those rates observed in the marine environment. We shift our attention to the Earth environment at 3.8 Gyr ago, where the earliest marine sediments are preserved. We calculate, consistent with the carbon isotope record and other considerations of the carbon cycle, that marine rates of primary production at this time were probably an order of magnitude (or more) less than today. We conclude that the flux of reduced species to the Earth surface at this time may have been sufficient to drive anaerobic ecosystems of sufficient activity to be consistent with the carbon isotope record. Conversely, an ecosystem based on oxygenic photosynthesis was also possible with complete removal of the oxygen by reaction with reduced species from the mantle. PMID:17008221

Kinetic Studies of the Cometabolism of 1,4-DIOXANE and Chlorinated Aliphatic Hydrocarbon Mixtures by Rhodococcus Rhodochrous Grown on Isobutane

NASA Astrophysics Data System (ADS)

Rolston, H. M.; Semprini, L.; Thankitkul, S.; Azizian, M.; Hyman, M. R.

2016-12-01

1,4-dioxane (1,4-D) is a frequently observed groundwater contaminant due to its use as a stabilizer in commercial solvent formulations. In situ bioremediation could potentially provide a large cost savings for treatment of mixtures of chlorinated aliphatic hydrocarbons (CAHs) that include 1,4-D. Aerobic cometabolism is a particularly attractive option, as microorganisms can be stimulated in situ using specific primary substrates. Results will be presented that show the model isobutane-metabolizing bacteria, Rhodococcus rhodochrous (ATCC 21198), has the ability to transform 14-D at high rates and transformation capacities to concentrations below the drinking water screening level of 0.67 µg L-1. Resting cell transformation tests showed 1,4-D and a broad range of CAHs can be cometabolized by ATCC 21198. The maximum transformation rate (kmax) and the half-substrate coefficient (Ks) were determined for isobutane (the growth substrate), 1,4-D, 1,1,1-trichloroethane (1,1,1-TCA), 1,1,2-trichloroethane (1,1,2-TCA), 1,1-dichloroethane (1,1-DCA); 1,2-dichloroethane ((1,2-DCA) and 1,1-dichloroethene (1,1-DCE). Of the CAHs tested, 1,1-DCA had the highest kmax, approximately 25% of that for isobutane utilization, while 1,1,1-TCA had the lowest kmax, approximately 2% of isobutane's. 1,4-D was rapidly transformed and had a kmax 25% of that of isobutane. ATCC 21198 effectively transformed mixtures of 1,4-D, 1,1-DCE, 1,2-DCA and 1,1,1-TCA, both in the presence and absence isobutane. Model simulations were performed for the simultaneous cometabolism of 1,4-D and CAH mixtures by ATCC 21198, that included inhibition among the contaminants and isobutane , and terms for a limited transformation capacity. A good match to experimental observations was obtaining using the independently measured rate parameters. Results of model simulations will also be presented using a reactive transport model to evaluate conditions of in situ bioremediation using strain ATCC 21198.

Coupling hydrothermal liquefaction and anaerobic digestion for energy valorization from model biomass feedstocks.

PubMed

Posmanik, Roy; Labatut, Rodrigo A; Kim, Andrew H; Usack, Joseph G; Tester, Jefferson W; Angenent, Largus T

2017-06-01

Hydrothermal liquefaction converts food waste into oil and a carbon-rich hydrothermal aqueous phase. The hydrothermal aqueous phase may be converted to biomethane via anaerobic digestion. Here, the feasibility of coupling hydrothermal liquefaction and anaerobic digestion for the conversion of food waste into energy products was examined. A mixture of polysaccharides, proteins, and lipids, representing food waste, underwent hydrothermal processing at temperatures ranging from 200 to 350°C. The anaerobic biodegradability of the hydrothermal aqueous phase was examined through conducting biochemical methane potential assays. The results demonstrate that the anaerobic biodegradability of the hydrothermal aqueous phase was lower when the temperature of hydrothermal processing increased. The chemical composition of the hydrothermal aqueous phase affected the anaerobic biodegradability. However, no inhibition of biodegradation was observed for most samples. Combining hydrothermal and anaerobic digestion may, therefore, yield a higher energetic return by converting the feedstock into oil and biomethane. Copyright © 2017 Elsevier Ltd. All rights reserved.

Anaerobic degradation of inedible crop residues produced in a Controlled Ecological Life Support System

NASA Technical Reports Server (NTRS)

Schwingel, W. R.; Sager, J. C.

1996-01-01

An anaerobic reactor seeded with organisms from an anaerobic lagoon was used to study the degradation of inedible crop residues from potato and wheat crops grown in a closed environment. Conversion of this biomass into other products was also evaluated. Degradation of wheat volatile solids was about 25% where that of potato was about 50%. The main product of the anaerobic fermentation of both crops was acetic acid with smaller quantities of propionate and butyrate produced. Nitrate, known to be high in concentration in inedible potato and wheat biomass grown hydroponically, was converted to ammonia in the anaerobic reactor. Both volatile fatty acid and ammonia production may have implications in a crop production system.

Fermentative hydrogen production from soybean protein processing wastewater in an anaerobic baffled reactor (ABR) using anaerobic mixed consortia.

PubMed

Zhu, Ge-fu; Li, Jian-zheng; Liu, Chao-xiang

2012-09-01

Fermentative H(2) production from soybean protein processing wastewater (SPPW) was investigated in a four-compartment anaerobic baffled reactor (ABR) using anaerobic mixed cultures under continuous flow condition in the present study. After being inoculated with aerobic activated sludge and operated at the inoculants of 5.98 gVSS L(-1), COD of 5000 mg L(-1), HRT of 16 h and temperature of (35 ± 1) °C for 22 days, the ABR achieved stable ethanol-type fermentation. The specific hydrogen production rate of anaerobic activated sludge was 165 LH(2)kg MLVSS(-1) day(-1), the substrate conversion rate was 600.83 LH(2)kg COD(-1)and the COD removal efficiency was 44.73% at the stable operation status. The ABR system exhibited a better stability and higher hydrogen yields than continuous stirring tank reactor under the same operational condition. The experimental data documented the feasibility of substrate degradation along with molecular H(2) generation utilizing SPPW as primary carbon source in the ABR system.

Anaerobic degradation of a mixture of MtBE, EtBE, TBA, and benzene under different redox conditions.

PubMed

van der Waals, Marcelle J; Pijls, Charles; Sinke, Anja J C; Langenhoff, Alette A M; Smidt, Hauke; Gerritse, Jan

2018-04-01

The increasing use of biobased fuels and fuel additives can potentially change the typical fuel-related contamination in soil and groundwater. Anaerobic biotransformation of the biofuel additive ethyl tert-butyl ether (EtBE), as well as of methyl tert-butyl ether (MtBE), benzene, and tert-butyl alcohol (TBA, a possible oxygenate metabolite), was studied at an industrially contaminated site and in the laboratory. Analysis of groundwater samples indicated that in the field MtBE was degraded, yielding TBA as major product. In batch microcosms, MtBE was degraded under different conditions: unamended control, with medium without added electron acceptors, or with ferrihydrite or sulfate (with or without medium) as electron acceptor, respectively. Degradation of EtBE was not observed under any of these conditions tested. TBA was partially depleted in parallel with MtBE. Results of microcosm experiments with MtBE substrate analogues, i.e., syringate, vanillate, or ferulate, were in line with the hypothesis that the observed TBA degradation is a cometabolic process. Microcosms with ferulate, syringate, isopropanol, or diethyl ether showed EtBE depletion up to 86.5% of the initial concentration after 83 days. Benzene was degraded in the unamended controls, with medium without added electron acceptors and with ferrihydrite, sulfate, or chlorate as electron acceptor, respectively. In the presence of nitrate, benzene was only degraded after addition of an anaerobic benzene-degrading community. Nitrate and chlorate hindered MtBE, EtBE, and TBA degradation.

Cometabolic Degradation of Naproxen by Planococcus sp. Strain S5.

PubMed

Domaradzka, Dorota; Guzik, Urszula; Hupert-Kocurek, Katarzyna; Wojcieszyńska, Danuta

Naproxen is a non-steroidal anti-inflammatory drug frequently detected in the influent and effluent of sewage treatment plants. The Gram-positive strain Planococcus sp. S5 was able to remove approximately 30 % of naproxen after 35 days of incubation in monosubstrate culture. Under cometabolic conditions, with glucose or phenol as a growth substrate, the degradation efficiency of S5 increased. During 35 days of incubation, 75.14 ± 1.71 % and 86.27 ± 2.09 % of naproxen was degraded in the presence of glucose and phenol, respectively. The highest rate of naproxen degradation observed in the presence of phenol may be connected with the fact that phenol is known to induce enzymes responsible for aromatic ring cleavage. The activity of phenol monooxygenase, naphthalene monooxygenase, and hydroxyquinol 1,2-dioxygenase was indicated in Planococcus sp. S5 culture with glucose or phenol as a growth substrate. It is suggested that these enzymes may be engaged in naproxen degradation.

Anaerobic

MedlinePlus

... oxygen." The term has many uses in medicine. Anaerobic bacteria are germs that can survive and grow where ... Infections like tetanus and gangrene are caused by anaerobic bacteria. Anaerobic infections typically cause abscesses (buildups of pus), ...

Providing Additional Support for MNA by Including Quantitative Lines of Evidence for Abiotic Degradation and Co-metabolic Oxidation of Chlorinated Ethylenes

DTIC Science & Technology

2017-02-08

cost benefit of the technology. 7.1 COST MODEL A simple cost model for the technology is presented so that a remediation professional can understand...reporting costs . The benefit of the qPCR analyses is that they allow the user to determine if aerobic cometabolism is possible. Because the PHE and...of Chlorinated Ethylenes February 2017 This document has been cleared for public release; Distribution Statement A Page Intentionally Left

Photoenhanced anaerobic digestion of organic acids

DOEpatents

Weaver, Paul F.

1990-01-01

A process is described for rapid conversion of organic acids and alcohols anaerobic digesters into hydrogen and carbon dioxide, the optimal precursor substrates for production of methane. The process includes addition of photosynthetic bacteria to the digester and exposure of the bacteria to radiant energy (e.g., solar energy). The process also increases the pH stability of the digester to prevent failure of the digester. Preferred substrates for photosynthetic bacteria are the organic acid and alcohol waste products of fermentative bacteria. In mixed culture with methanogenic bacteria or in defined co-culture with non-aceticlastic methanogenic bacteria, photosynthetic bacteria are capable of facilitating the conversion or organic acids and alcohols into methane with low levels of light energy input.

Degradation of toxaphene in water during anaerobic and aerobic conditions.

PubMed

LacayoR, M; van Bavel, B; Mattiasson, B

2004-08-01

The degradation of technical toxaphene in water with two kinds of bioreactors operating in sequence was studied. One packed bed reactor was filled with Poraver (foam glass particles) running at anaerobic conditions and one suspended carrier biofilm reactor working aerobically. Chemical oxygen demand (COD), chloride, sulphate, pH, dissolved oxygen, total toxaphene and specific toxaphene isomers were measured. After 6 weeks approx. 87% of the total toxaphene was degraded reaching 98% by week 39. The majority of the conversion took place in the anaerobic reactor. The concentrations of toxaphene isomers with more chlorine substituents decreased more rapidly than for isomers with less chlorine substituents.

Redundancy in Anaerobic Digestion Microbiomes during Disturbances by the Antibiotic Monensin

PubMed Central

Spirito, Catherine M.; Daly, Sarah E.; Werner, Jeffrey J.

2018-01-01

ABSTRACT The antibiotic monensin is fed to dairy cows to increase milk production efficiency. A fraction of this monensin is excreted into the cow manure. Previous studies have found that cow manure containing monensin can negatively impact the performance of anaerobic digesters, especially upon first introduction. Few studies have examined whether the anaerobic digester microbiome can adapt to monensin during the operating time. Here, we conducted a long-term time series study of four lab-scale anaerobic digesters fed with cow manure. We examined changes in both the microbiome composition and function of the anaerobic digesters when subjected to the dairy antibiotic monensin. In our digesters, monensin was not rapidly degraded under anaerobic conditions. The two anaerobic digesters that were subjected to manure from monensin feed-dosed cows exhibited relatively small changes in microbiome composition and function due to relatively low monensin concentrations. At higher concentrations of monensin, which we dosed directly to control manure (from dairy cows without monensin), we observed major changes in the microbiome composition and function of two anaerobic digesters. A rapid introduction of monensin to one of these anaerobic digesters led to the impairment of methane production. Conversely, more gradual additions of the same concentrations of monensin to the other anaerobic digester led to the adaptation of the anaerobic digester microbiomes to the relatively high monensin concentrations. A member of the candidate OP11 (Microgenomates) phylum arose in this anaerobic digester and appeared to be redundant with certain Bacteroidetes phylum members, which previously were dominating. IMPORTANCE Monensin is a common antibiotic given to dairy cows in the United States and is partly excreted with dairy manure. An improved understanding of how monensin affects the anaerobic digester microbiome composition and function is important to prevent process failure for farm

Anaerobic biotransformation of organoarsenical pesticides monomethylarsonic acid and dimethylarsinic acid

USGS Publications Warehouse

Sierra-Alvarez, R.; Yenal, U.; Feld, J.A.; Kopplin, M.; Gandolfi, A.J.; Garbarino, J.R.

2006-01-01

Monomethylarsonic acid (MMAV) and dimethylarsinic acid (DMAV) are extensively utilized as pesticides, introducing large quantities of arsenic into the environment. Once released into the environment, these organoarsenicals are subject to microbial reactions. Aerobic biodegradation of MMAV and DMAV has been evaluated, but little is known about their fate in anaerobic environments. The objective of this study was to evaluate the biotransformation of MMAV and DMAV in anaerobic sludge. Biologically mediated conversion occurred under methanogenic or sulfate-reducing conditions but not in the presence of nitrate. Monomethylarsonous acid (MMAIII) was consistently observed as an important metabolite of MMAV degradation, and it was recovered in molar yields ranging from 5 to 47%. The main biotransformation product identified from DMAV metabolism was MMAV, which was recovered in molar yields ranging from 8 to 65%. The metabolites indicate that reduction and demethylation are important steps in the anaerobic bioconversion of MMAV and DMAV, respectively. ?? 2006 American Chemical Society.

High-strength fermentable wastewater reclamation through a sequential process of anaerobic fermentation followed by microalgae cultivation.

PubMed

Qi, Wenqiang; Chen, Taojing; Wang, Liang; Wu, Minghong; Zhao, Quanyu; Wei, Wei

2017-03-01

In this study, the sequential process of anaerobic fermentation followed by microalgae cultivation was evaluated from both nutrient and energy recovery standpoints. The effects of different fermentation type on the biogas generation, broth metabolites' composition, algal growth and nutrients' utilization, and energy conversion efficiencies for the whole processes were discussed. When the fermentation was designed to produce hydrogen-dominating biogas, the total energy conversion efficiency (TECE) of the sequential process was higher than that of the methane fermentation one. With the production of hydrogen in anaerobic fermentation, more organic carbon metabolites were left in the broth to support better algal growth with more efficient incorporation of ammonia nitrogen. By applying the sequential process, the heat value conversion efficiency (HVCE) for the wastewater could reach 41.2%, if methane was avoided in the fermentation biogas. The removal efficiencies of organic metabolites and NH 4 + -N in the better case were 100% and 98.3%, respectively. Copyright © 2016 Elsevier Ltd. All rights reserved.

[Anaerobic bacteria isolated from patients with suspected anaerobic infections].

PubMed

Ercis, Serpil; Tunçkanat, Ferda; Hasçelik, Gülşen

2005-10-01

The study involved 394 clinical samples sent to the Clinical Microbiology Laboratory of Hacettepe University Adult Hospital between January 1997 and May 2004 for anaerobic cultivation. Since multiple cultures from the same clinical samples of the same patient were excluded, the study was carried on 367 samples. The anaerobic cultures were performed in anaerobic jar using AnaeroGen kits (Oxoid, Basingstoke, U.K.) or GENbox (bioMérieux, Lyon, France). The isolates were identified by both classical methods and "BBL Crystal System" (Becton Dickinson, U.S.A.). While no growth was detected in 120 (32.7%) of the clinical samples studied, in 144 samples (39.2%) only aerobes, in 28 (7.6%) only anaerobes and in 75 (20.5%) of the samples both aerobes and anaerobes were isolated. The number of the anaerobic isolates was 217 from 103 samples with anaerobic growth. Of these 103 samples 15 showed single bacterial growth whereas in 88 samples multiple bacterial isolates were detected. Anaerobic isolates consisted of 92 Gram negative bacilli (Bacteroides spp. 50, Prevotella spp. 14, Porphyromonas spp. 10, Fusobacterium spp. 7, Tisierella spp. 2, unidentified 9), 57 Gram positive bacilli (Clostridium spp.17, Propionibacterium spp. 16, Lactobacillus spp. 8, Actinomyces spp. 5, Eubacterium spp. 2, Bifidobacterium adolescentis 1, Mobiluncus mulieris 1, unidentified nonspore forming rods 7), 61 Gram positive cocci (anaerobic cocci 44, microaerophilic cocci 17), and 7 Gram negative cocci (Veillonella spp.). In conclusion, in the samples studied with prediagnosis of anaerobic infection, Bacteroides spp. (23%) were the most common bacteria followed by anaerobic Gram positive cocci (20.3%) and Clostridium spp (7.8%).

Growth media in anaerobic fermentative processes: The underestimated potential of thermophilic fermentation and anaerobic digestion.

PubMed

Hendriks, A T W M; van Lier, J B; de Kreuk, M K

Fermentation and anaerobic digestion of organic waste and wastewater is broadly studied and applied. Despite widely available results and data for these processes, comparison of the generated results in literature is difficult. Not only due to the used variety of process conditions, but also because of the many different growth media that are used. Composition of growth media can influence biogas production (rates) and lead to process instability during anaerobic digestion. To be able to compare results of the different studies reported, and to ensure nutrient limitation is not influencing observations ascribed to process dynamics and/or reaction kinetics, a standard protocol for creating a defined growth medium for anaerobic digestion and mixed culture fermentation is proposed. This paper explains the role(s) of the different macro- and micronutrients, as well as the choices for a growth medium formulation strategy. In addition, the differences in nutrient requirements between mesophilic and thermophilic systems are discussed as well as the importance of specific trace metals regarding specific conversion routes and the possible supplementary requirement of vitamins. The paper will also give some insight into the bio-availability and toxicity of trace metals. A remarkable finding is that mesophilic and thermophilic enzymes are quite comparable at their optimum temperatures. This has consequences for the trace metal requirements of thermophiles under certain conditions. Under non-limiting conditions, the trace metal requirement of thermophilic systems is about 3 times higher than for mesophilic systems. Copyright © 2017 Elsevier Inc. All rights reserved.

Co-metabolism of substrates by Bacillus thuringiensis regulates polyhydroxyalkanoate co-polymer composition.

PubMed

Ray, Subhasree; Kalia, Vipin Chandra

2017-01-01

Polyhydroxyalkanoate (PHA) production by Bacillus thuringiensis EGU45 was studied by co-metabolism of crude glycerol (CG) (1%, v/v), glucose (0.05-0.5%, w/v) and propionic acid (0.05-0.5%, v/v) under batch (shake flask) culture conditions. Glycerol+PA combination resulted in 15-100mg/L PHA co-polymers with a HV content of 33-81mol%. The addition of NH 4 Cl (0.5%, w/v) to CG+PA enhanced PHA production by 1.55-fold, with a HV content of 58-70mol%. The time period of incubation of PA to the feed: CG+glucose was optimized to be 3h after initiation of fermentation. The PHA contents were found to be stable at 1900-2050mg/L up scaling from 0.4 to 2.0L feed material. Biochemical characterization through GC-MS of PHA co-polymer revealed the presence of 3-hydroxydecanoate (3-HDD), 3-hydroxyoctadecanoate (3HOD), 3-hydroxyhexadecanoate (3HHD). Copyright © 2016 Elsevier Ltd. All rights reserved.

Toxicity of nonylphenol diethoxylate in lab-scale anaerobic digesters.

PubMed

Bozkurt, Hande; Sanin, F Dilek

2014-06-01

Nonylphenol compounds have high commercial, industrial and domestic uses owing to their surface active properties. In addition to their toxic, carcinogenic and persistent characteristics; they have drawn the attention of scientists lately due to their endocrine disrupting properties. Their widespread use and disposal cause them to enter wastewater treatment systems at high concentrations. Since they are highly persistent and hydrophobic, they accumulate mostly on sludge. In this study using Anaerobic Toxicity Assay (ATA) tests, the toxicity of a model nonylphenol compound, nonylphenol diethoxylate (NP2EO), for anaerobic digestion of sludge was determined. The test bottles were dosed with NP2EO in acetone, with concentrations ranging from 1 mg L(-1) to 30 mg L(-1). During the tests, gas productions and compositions in terms of methane and carbon dioxide were monitored. To be able to judge about the fate, the target compounds were extracted from water and sludge and analyzed using GC/MS. The sludge samples used for assembling the reactors were found to contain NP and NP1EO but no NP2EO. After the assay was completed, all the NP2EO spiked into the live reactors was found to disappear. The increase seen in NP1EO and NP and further accumulation of NP in the system, indicated the conversion of NP2EO to these metabolites. On the other hand, no conversion was observed in abiotic reactors. Inhibition of NP2EO for anaerobic microorganisms was not observed throughout the tests considering the biogas production of the test reactors in comparison to the control reactors. Copyright © 2013 Elsevier Ltd. All rights reserved.

Performance assessment of two-stage anaerobic digestion of kitchen wastes.

PubMed

Bo, Zhang; Pin-Jing, He

2014-01-01

This study is aimed at investigating the performance of the two-phase anaerobic digestion of kitchen wastes in a lab-scale setup. The semi-continuous experiment showed that the two-phase anaerobic digestion of kitchen wastes had a bioconversion rate of 83%, biogas yield of 338 mL x (g chemical oxygen demand (COD))(-1) and total solid conversion of 63% when the entire two-phase anaerobic digestion process was subjected to an organic loading rate (OLR) of 10.7 g x (L d)(-1). In the hydrolysis-acidogenesis process, the efficiency of solubilization decreased from 72.6% to 41.1%, and the acidogenesis efficiency decreased from 31.8% to 17.8% with an increase in the COD loading rate. On the other hand, the performance of the subsequent methanogenic process was not susceptible to the increase in the feeding COD loading rate in the hydrolysis-acidogenesis stage. Lactic acid was one of the main fermentation products, accounting for over 40% of the total soluble COD in the fermentation liquid. The batch experiments indicated that the lactic acid was the earliest predominant fermentation product, and distributions of fermentation products were pH dependent. Results showed that increasing the feeding OLR of kitchen wastes made the two-stage anaerobic digestion process more effective. Moreover, there was a potential improvement in the performance of anaerobic digestion of kitchen wastes with a corresponding improvement in the hydrolysis process.

Microbial Ecology of Anaerobic Digesters: The Key Players of Anaerobiosis

PubMed Central

Ali Shah, Fayyaz; Mahmood, Qaisar; Maroof Shah, Mohammad; Pervez, Arshid; Ahmad Asad, Saeed

2014-01-01

Anaerobic digestion is the method of wastes treatment aimed at a reduction of their hazardous effects on the biosphere. The mutualistic behavior of various anaerobic microorganisms results in the decomposition of complex organic substances into simple, chemically stabilized compounds, mainly methane and CO2. The conversions of complex organic compounds to CH4 and CO2 are possible due to the cooperation of four different groups of microorganisms, that is, fermentative, syntrophic, acetogenic, and methanogenic bacteria. Microbes adopt various pathways to evade from the unfavorable conditions in the anaerobic digester like competition between sulfate reducing bacteria (SRB) and methane forming bacteria for the same substrate. Methanosarcina are able to use both acetoclastic and hydrogenotrophic pathways for methane production. This review highlights the cellulosic microorganisms, structure of cellulose, inoculum to substrate ratio, and source of inoculum and its effect on methanogenesis. The molecular techniques such as DGGE (denaturing gradient gel electrophoresis) utilized for dynamic changes in microbial communities and FISH (fluorescent in situ hybridization) that deal with taxonomy and interaction and distribution of tropic groups used are also discussed. PMID:24701142

Microbial ecology of anaerobic digesters: the key players of anaerobiosis.

PubMed

Ali Shah, Fayyaz; Mahmood, Qaisar; Maroof Shah, Mohammad; Pervez, Arshid; Ahmad Asad, Saeed

2014-01-01

Anaerobic digestion is the method of wastes treatment aimed at a reduction of their hazardous effects on the biosphere. The mutualistic behavior of various anaerobic microorganisms results in the decomposition of complex organic substances into simple, chemically stabilized compounds, mainly methane and CO2. The conversions of complex organic compounds to CH4 and CO2 are possible due to the cooperation of four different groups of microorganisms, that is, fermentative, syntrophic, acetogenic, and methanogenic bacteria. Microbes adopt various pathways to evade from the unfavorable conditions in the anaerobic digester like competition between sulfate reducing bacteria (SRB) and methane forming bacteria for the same substrate. Methanosarcina are able to use both acetoclastic and hydrogenotrophic pathways for methane production. This review highlights the cellulosic microorganisms, structure of cellulose, inoculum to substrate ratio, and source of inoculum and its effect on methanogenesis. The molecular techniques such as DGGE (denaturing gradient gel electrophoresis) utilized for dynamic changes in microbial communities and FISH (fluorescent in situ hybridization) that deal with taxonomy and interaction and distribution of tropic groups used are also discussed.

Potential for cometabolic biodegradation of 1,4-dioxane in aquifers with methane or ethane as primary substrates.

PubMed

Hatzinger, Paul B; Banerjee, Rahul; Rezes, Rachael; Streger, Sheryl H; McClay, Kevin; Schaefer, Charles E

2017-12-01

The objective of this research was to evaluate the potential for two gases, methane and ethane, to stimulate the biological degradation of 1,4-dioxane (1,4-D) in groundwater aquifers via aerobic cometabolism. Experiments with aquifer microcosms, enrichment cultures from aquifers, mesophilic pure cultures, and purified enzyme (soluble methane monooxygenase; sMMO) were conducted. During an aquifer microcosm study, ethane was observed to stimulate the aerobic biodegradation of 1,4-D. An ethane-oxidizing enrichment culture from these samples, and a pure culture capable of growing on ethane (Mycobacterium sphagni ENV482) that was isolated from a different aquifer also biodegraded 1,4-D. Unlike ethane, methane was not observed to appreciably stimulate the biodegradation of 1,4-D in aquifer microcosms or in methane-oxidizing mixed cultures enriched from two different aquifers. Three different pure cultures of mesophilic methanotrophs also did not degrade 1,4-D, although each rapidly oxidized 1,1,2-trichloroethene (TCE). Subsequent studies showed that 1,4-D is not a substrate for purified sMMO enzyme from Methylosinus trichosporium OB3b, at least not at the concentrations evaluated, which significantly exceeded those typically observed at contaminated sites. Thus, our data indicate that ethane, which is a common daughter product of the biotic or abiotic reductive dechlorination of chlorinated ethanes and ethenes, may serve as a substrate to enhance 1,4-D degradation in aquifers, particularly in zones where these products mix with aerobic groundwater. It may also be possible to stimulate 1,4-D biodegradation in an aerobic aquifer through addition of ethane gas. Conversely, our results suggest that methane may have limited importance in natural attenuation or for enhancing biodegradation of 1,4-D in groundwater environments.

Microalgae Cultivation on Anaerobic Digestate of Municipal Wastewater, Sewage Sludge and Agro-Waste.

PubMed

Zuliani, Luca; Frison, Nicola; Jelic, Aleksandra; Fatone, Francesco; Bolzonella, David; Ballottari, Matteo

2016-10-10

Microalgae are fast-growing photosynthetic organisms which have the potential to be exploited as an alternative source of liquid fuels to meet growing global energy demand. The cultivation of microalgae, however, still needs to be improved in order to reduce the cost of the biomass produced. Among the major costs encountered for algal cultivation are the costs for nutrients such as CO₂, nitrogen and phosphorous. In this work, therefore, different microalgal strains were cultivated using as nutrient sources three different anaerobic digestates deriving from municipal wastewater, sewage sludge or agro-waste treatment plants. In particular, anaerobic digestates deriving from agro-waste or sewage sludge treatment induced a more than 300% increase in lipid production per volume in Chlorella vulgaris cultures grown in a closed photobioreactor, and a strong increase in carotenoid accumulation in different microalgae species. Conversely, a digestate originating from a pilot scale anaerobic upflow sludge blanket (UASB) was used to increase biomass production when added to an artificial nutrient-supplemented medium. The results herein demonstrate the possibility of improving biomass accumulation or lipid production using different anaerobic digestates.

Microalgae Cultivation on Anaerobic Digestate of Municipal Wastewater, Sewage Sludge and Agro-Waste

PubMed Central

Zuliani, Luca; Frison, Nicola; Jelic, Aleksandra; Fatone, Francesco; Bolzonella, David; Ballottari, Matteo

2016-01-01

Microalgae are fast-growing photosynthetic organisms which have the potential to be exploited as an alternative source of liquid fuels to meet growing global energy demand. The cultivation of microalgae, however, still needs to be improved in order to reduce the cost of the biomass produced. Among the major costs encountered for algal cultivation are the costs for nutrients such as CO2, nitrogen and phosphorous. In this work, therefore, different microalgal strains were cultivated using as nutrient sources three different anaerobic digestates deriving from municipal wastewater, sewage sludge or agro-waste treatment plants. In particular, anaerobic digestates deriving from agro-waste or sewage sludge treatment induced a more than 300% increase in lipid production per volume in Chlorella vulgaris cultures grown in a closed photobioreactor, and a strong increase in carotenoid accumulation in different microalgae species. Conversely, a digestate originating from a pilot scale anaerobic upflow sludge blanket (UASB) was used to increase biomass production when added to an artificial nutrient-supplemented medium. The results herein demonstrate the possibility of improving biomass accumulation or lipid production using different anaerobic digestates. PMID:27735859

Performance evaluation of the sulfur-redox-reaction-activated up-flow anaerobic sludge blanket and down-flow hanging sponge anaerobic/anoxic sequencing batch reactor system for municipal sewage treatment.

PubMed

Hatamoto, Masashi; Ohtsuki, Kota; Maharjan, Namita; Ono, Shinya; Dehama, Kazuya; Sakamoto, Kenichi; Takahashi, Masanobu; Yamaguchi, Takashi

2016-03-01

A sulfur-redox-reaction-activated up-flow anaerobic sludge blanket (UASB) and down-flow hanging sponge (DHS) system, combined with an anaerobic/anoxic sequencing batch reactor (A2SBR), has been used for municipal sewage treatment for over 2 years. The present system achieved a removal rate of 95±14% for BOD, 74±22% for total nitrogen, and 78±25% for total phosphorus, including low water temperature conditions. Sludge conversion rates during the operational period were 0.016 and 0.218 g-VSS g-COD-removed(-1) for the UASB, and DHS, respectively, which are similar to a conventional UASB-DHS system, which is not used of sulfur-redox-reaction, for sewage treatment. Using the sulfur-redox reaction made advanced treatment of municipal wastewater with minimal sludge generation possible, even in winter. Furthermore, the occurrence of a unique phenomenon, known as the anaerobic sulfur oxidation reaction, was confirmed in the UASB reactor under the winter season. Copyright © 2016. Published by Elsevier Ltd.

Temperature-phased anaerobic digestion of food waste: A comparison with single-stage digestions based on performance and energy balance.

PubMed

Xiao, Benyi; Qin, Yu; Zhang, Wenzhe; Wu, Jing; Qiang, Hong; Liu, Junxin; Li, Yu-You

2018-02-01

The temperature-phased anaerobic digestion (TPAD) of food waste was studied for the purpose of comparing with single-stage mesophilic and thermophilic anaerobic digestion. The biogas and methane yields in the TPAD during the steady period were 0.759 ± 0.115 L/g added VS and 0.454 ± 0.201 L/g added VS, which were lower than those in the two single-stage anaerobic digestion. The improper sludge retention time may be the reason for the lower biogas and methane production in TPAD. The removal of volatile solids in the TPAD was 78.55 ± 4.59% and the lowest among the three anaerobic digestion processes. The reaction ratios of the four anaerobic digestion steps in the TPAD were all lower than those in the two single-stage anaerobic digestion. The energy conversion efficiency of the degraded substrate in the TPAD was similar with those in single-stage mesophilic and thermophilic anaerobic digestion systems. Copyright © 2017 Elsevier Ltd. All rights reserved.

The role of anaerobic digestion in the emerging energy economy.

PubMed

Batstone, Damien John; Virdis, Bernardino

2014-06-01

Anaerobic digestion is the default process for biological conversion of residue organics to renewable energy and biofuel in the form of methane. However, its scope of application is expanding, due to availability of new technologies, and the emerging drivers of energy and nutrient conservation and recovery. Here, we outline two of these new application areas, namely wastewater nutrient and energy recovery, and generation of value added chemicals through mixed culture biotechnology. There exist two options for nutrient and energy recovery from domestic wastewater: low energy mainline and partition-release-recovery. Both are heavily dependent on anaerobic digestion as an energy generating and nutrient release step, and have been enabled by new technologies such as low emission anaerobic membrane processes. The area of mixed culture biotechnology has been previously identified as a key industrial opportunity, but is now moving closer to application due application of existing and new technologies. As well as acting as a core technology option in bioproduction, anaerobic digestion has a key role in residual waste valorization and generation of energy for downstream processing. These new application areas and technologies are emerging simultaneously with substantial advances in knowledge of underlying mechanisms such as electron transfer, understanding of which is critical to development of the new application areas. Copyright © 2014 Elsevier Ltd. All rights reserved.

Anaerobic Oxidation of Benzene by the Hyperthermophilic Archaeon Ferroglobus placidus▿†

PubMed Central

Holmes, Dawn E.; Risso, Carla; Smith, Jessica A.; Lovley, Derek R.

2011-01-01

Anaerobic benzene oxidation coupled to the reduction of Fe(III) was studied in Ferroglobus placidus in order to learn more about how such a stable molecule could be metabolized under strict anaerobic conditions. F. placidus conserved energy to support growth at 85°C in a medium with benzene provided as the sole electron donor and Fe(III) as the sole electron acceptor. The stoichiometry of benzene loss and Fe(III) reduction, as well as the conversion of [14C]benzene to [14C]carbon dioxide, was consistent with complete oxidation of benzene to carbon dioxide with electron transfer to Fe(III). Benzoate, but not phenol or toluene, accumulated at low levels during benzene metabolism, and [14C]benzoate was produced from [14C]benzene. Analysis of gene transcript levels revealed increased expression of genes encoding enzymes for anaerobic benzoate degradation during growth on benzene versus growth on acetate, but genes involved in phenol degradation were not upregulated during growth on benzene. A gene for a putative carboxylase that was more highly expressed in benzene- than in benzoate-grown cells was identified. These results suggest that benzene is carboxylated to benzoate and that phenol is not an important intermediate in the benzene metabolism of F. placidus. This is the first demonstration of a microorganism in pure culture that can grow on benzene under strict anaerobic conditions and for which there is strong evidence for degradation of benzene via clearly defined anaerobic metabolic pathways. Thus, F. placidus provides a much-needed pure culture model for further studies on the anaerobic activation of benzene in microorganisms. PMID:21742914

Engineering a synthetic anaerobic respiration for reduction of xylose to xylitol using NADH output of glucose catabolism by Escherichia coli AI21.

PubMed

Iverson, Andrew; Garza, Erin; Manow, Ryan; Wang, Jinhua; Gao, Yuanyuan; Grayburn, Scott; Zhou, Shengde

2016-04-16

Anaerobic rather than aerobic fermentation is preferred for conversion of biomass derived sugars to high value redox-neutral and reduced commodities. This will likely result in a higher yield of substrate to product conversion and decrease production cost since substrate often accounts for a significant portion of the overall cost. To this goal, metabolic pathway engineering has been used to optimize substrate carbon flow to target products. This approach works well for the production of redox neutral products such as lactic acid from redox neutral sugars using the reducing power NADH (nicotinamide adenine dinucleotide, reduced) generated from glycolysis (2 NADH per glucose equivalent). Nevertheless, greater than two NADH per glucose catabolized is needed for the production of reduced products (such as xylitol) from redox neutral sugars by anaerobic fermentation. The Escherichia coli strain AI05 (ΔfrdBC ΔldhA ΔackA Δ(focA-pflB) ΔadhE ΔptsG ΔpdhR::pflBp 6-(aceEF-lpd)), previously engineered for reduction of xylose to xylitol using reducing power (NADH equivalent) of glucose catabolism, was further engineered by 1) deleting xylAB operon (encoding for xylose isomerase and xylulokinase) to prevent xylose from entering the pentose phosphate pathway; 2) anaerobically expressing the sdhCDAB-sucABCD operon (encoding for succinate dehydrogenase, α-ketoglutarate dehydrogenase and succinyl-CoA synthetase) to enable an anaerobically functional tricarboxcylic acid cycle with a theoretical 10 NAD(P)H equivalent per glucose catabolized. These reducing equivalents can be oxidized by synthetic respiration via xylose reduction, producing xylitol. The resulting strain, AI21 (pAI02), achieved a 96 % xylose to xylitol conversion, with a yield of 6 xylitol per glucose catabolized (molar yield of xylitol per glucose consumed (YRPG) = 6). This represents a 33 % improvement in xylose to xylitol conversion, and a 63 % increase in xylitol yield per glucose catabolized over

Metabolic regulation as a consequence of anaerobic 5-methylthioadenosine recycling in Rhodospirillum rubrum

DOE PAGES

North, Justin A.; Sriram, Jaya; Chourey, Karuna; ...

2016-07-12

Rhodospirillum rubrum possesses a novel oxygen-independent, aerobic methionine salvage pathway (MSP) for recycling methionine from 5-methylthioadenosine (MTA), the MTA-isoprenoid shunt. This organism can also metabolize MTA as a sulfur source under anaerobic conditions, suggesting that the MTA-isoprenoid shunt may also function anaerobically as well. In this study, deep proteomics profiling, directed metabolite analysis, and reverse transcriptase quantitative PCR (RT-qPCR) revealed metabolic changes in response to anaerobic growth on MTA versus sulfate as sole sulfur source. The abundance of protein levels associated with methionine transport, cell motility, and chemotaxis increased in the presence of MTA over that in the presence ofmore » sulfate. Purine salvage from MTA resulted primarily in hypoxanthine accumulation and a decrease in protein levels involved in GMP-to-AMP conversion to balance purine pools. Acyl coenzyme A (acyl-CoA) metabolic protein levels for lipid metabolism were lower in abundance, whereas poly-β-hydroxybutyrate synthesis and storage were increased nearly 10-fold. The known R. rubrum aerobic MSP was also shown to be upregulated, to function anaerobically, and to recycle MTA. This suggested that other organisms with gene homologues for the MTA-isoprenoid shunt may also possess a functioning anaerobic MSP. In support of our previous findings that ribulose-1,5-carboxylase/oxygenase (RubisCO) is required for an apparently purely anaerobic MSP, RubisCO transcript and protein levels both increased in abundance by over 10-fold in cells grown anaerobically on MTA over those in cells grown on sulfate, resulting in increased intracellular RubisCO activity. Lastly, these results reveal for the first time global metabolic responses as a consequence of anaerobic MTA metabolism compared to using sulfate as the sulfur source.« less

Metabolic regulation as a consequence of anaerobic 5-methylthioadenosine recycling in Rhodospirillum rubrum

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

North, Justin A.; Sriram, Jaya; Chourey, Karuna

Rhodospirillum rubrum possesses a novel oxygen-independent, aerobic methionine salvage pathway (MSP) for recycling methionine from 5-methylthioadenosine (MTA), the MTA-isoprenoid shunt. This organism can also metabolize MTA as a sulfur source under anaerobic conditions, suggesting that the MTA-isoprenoid shunt may also function anaerobically as well. In this study, deep proteomics profiling, directed metabolite analysis, and reverse transcriptase quantitative PCR (RT-qPCR) revealed metabolic changes in response to anaerobic growth on MTA versus sulfate as sole sulfur source. The abundance of protein levels associated with methionine transport, cell motility, and chemotaxis increased in the presence of MTA over that in the presence ofmore » sulfate. Purine salvage from MTA resulted primarily in hypoxanthine accumulation and a decrease in protein levels involved in GMP-to-AMP conversion to balance purine pools. Acyl coenzyme A (acyl-CoA) metabolic protein levels for lipid metabolism were lower in abundance, whereas poly-β-hydroxybutyrate synthesis and storage were increased nearly 10-fold. The known R. rubrum aerobic MSP was also shown to be upregulated, to function anaerobically, and to recycle MTA. This suggested that other organisms with gene homologues for the MTA-isoprenoid shunt may also possess a functioning anaerobic MSP. In support of our previous findings that ribulose-1,5-carboxylase/oxygenase (RubisCO) is required for an apparently purely anaerobic MSP, RubisCO transcript and protein levels both increased in abundance by over 10-fold in cells grown anaerobically on MTA over those in cells grown on sulfate, resulting in increased intracellular RubisCO activity. Lastly, these results reveal for the first time global metabolic responses as a consequence of anaerobic MTA metabolism compared to using sulfate as the sulfur source.« less

Metabolic Regulation as a Consequence of Anaerobic 5-Methylthioadenosine Recycling in Rhodospirillum rubrum

PubMed Central

North, Justin A.; Sriram, Jaya; Chourey, Karuna; Ecker, Christopher D.; Sharma, Ritin; Wildenthal, John A.; Hettich, Robert L.

2016-01-01

ABSTRACT Rhodospirillum rubrum possesses a novel oxygen-independent, aerobic methionine salvage pathway (MSP) for recycling methionine from 5-methylthioadenosine (MTA), the MTA-isoprenoid shunt. This organism can also metabolize MTA as a sulfur source under anaerobic conditions, suggesting that the MTA-isoprenoid shunt may also function anaerobically as well. In this study, deep proteomics profiling, directed metabolite analysis, and reverse transcriptase quantitative PCR (RT-qPCR) revealed metabolic changes in response to anaerobic growth on MTA versus sulfate as sole sulfur source. The abundance of protein levels associated with methionine transport, cell motility, and chemotaxis increased in the presence of MTA over that in the presence of sulfate. Purine salvage from MTA resulted primarily in hypoxanthine accumulation and a decrease in protein levels involved in GMP-to-AMP conversion to balance purine pools. Acyl coenzyme A (acyl-CoA) metabolic protein levels for lipid metabolism were lower in abundance, whereas poly-β-hydroxybutyrate synthesis and storage were increased nearly 10-fold. The known R. rubrum aerobic MSP was also shown to be upregulated, to function anaerobically, and to recycle MTA. This suggested that other organisms with gene homologues for the MTA-isoprenoid shunt may also possess a functioning anaerobic MSP. In support of our previous findings that ribulose-1,5-carboxylase/oxygenase (RubisCO) is required for an apparently purely anaerobic MSP, RubisCO transcript and protein levels both increased in abundance by over 10-fold in cells grown anaerobically on MTA over those in cells grown on sulfate, resulting in increased intracellular RubisCO activity. These results reveal for the first time global metabolic responses as a consequence of anaerobic MTA metabolism compared to using sulfate as the sulfur source. PMID:27406564

Low-heat, mild alkaline pretreatment of switchgrass for anaerobic digestion.

PubMed

Jin, Guang; Bierma, Tom; Walker, Paul M

2014-01-01

This study examines the effectiveness of alkaline pretreatment under mild heat conditions (100°C or 212°F) on the anaerobic co-digestion of switchgrass. The effects of alkaline concentration, types of alkaline, heating time and rinsing were evaluated. In addition to batch studies, continuous-feed studies were performed in triplicate to identify potential digester operational problems caused by switchgrass co-digestion while accounting for uncertainty due to digester variability. Few studies have examined anaerobic digestion of switchgrass or the effects of mild heating to enhance alkaline pretreatment prior to biomass digestion. Results indicate that pretreatment can significantly enhance digestion of coarse-ground (≤ 0.78 cm particle size) switchgrass. Energy conversion efficiency as high as 63% was observed, and was comparable or superior to fine-grinding as a pretreatment method. The optimal NaOH concentration was found to be 5.5% (wt/wt alkaline/biomass) with a 91.7% moisture level. No evidence of operational problems such as solids build-up, poor mixing, or floating materials were observed. These results suggest the use of waste heat from a generator could reduce the concentration of alkaline required to adequately pretreat lignocellulosic feedstock prior to anaerobic digestion.

Clostridiumm ljungdahlii, an anaerobic ethanol and acetate producing microorganism

DOEpatents

Gaddy, James L.; Clausen, Edgar C.

1992-01-01

A newly discovered microorganism was isolated in a biologically pure culture and designated Clostridium ljungdahlii, having the identifying characteristics of ATCC No. 49587. Cultured in an aqueous nutrient medium under anaerobic conditions, this microorganism is capable of producing ethanol and acetate from CO and H.sub.2 O and/or CO.sub.2 and H.sub.2 in synthesis gas. Under optimal growth conditions, the microorganism produces acetate in preference to ethanol. Conversely, under non-growth conditions, ethanol production is favored over acetate.

Microbial communities change in an anaerobic digestion after application of microbial electrolysis cells.

PubMed

Lee, Beom; Park, Jun-Gyu; Shin, Won-Beom; Tian, Dong-Jie; Jun, Hang-Bae

2017-06-01

Microbial electrolysis cells (MECs) are being studied to improve the efficiency of anaerobic digesters and biogas production. In the present study, we investigated the effects of electrochemical reactions in AD-MEC (anaerobic digester combined with MECs) on changes in the microbial communities of bulk sludge through 454-pyrosequencing analysis, as well as the effect of these changes on anaerobic digestion. Methanobacterium beijingense and Methanobacterium petrolearium were the dominant archaeal species in AD, while Methanosarcina thermophila and Methanobacterium formicicum were dominant in AD-MEC at steady-state. There were no substantial differences in dominant bacterial species. Clostridia class was more abundant than Bacteroidia class in both reactors. Compared to AD, AD-MEC showed a 40% increase in overall bacterial population, increasing the removal of organic matters and the conversion of volatile fatty acids (VFAs). Thus, the MEC reaction more effectively converts organic matters to VFAs and activates microbial communities favorable for methane production. Copyright © 2017 Elsevier Ltd. All rights reserved.

Anaerobic digestion of food waste: A review focusing on process stability.

PubMed

Li, Lei; Peng, Xuya; Wang, Xiaoming; Wu, Di

2018-01-01

Food waste (FW) is rich in biomass energy, and increasing numbers of national programs are being established to recover energy from FW using anaerobic digestion (AD). However process instability is a common operational issue for AD of FW. Process monitoring and control as well as microbial management can be used to control instability and increase the energy conversion efficiency of anaerobic digesters. Here, we review research progress related to these methods and identify existing limitations to efficient AD; recommendations for future research are also discussed. Process monitoring and control are suitable for evaluating the current operational status of digesters, whereas microbial management can facilitate early diagnosis and process optimization. Optimizing and combining these two methods are necessary to improve AD efficiency. Copyright © 2017 Elsevier Ltd. All rights reserved.

Anaerobic treatment of coconut husk liquor for biogas production.

PubMed

Leitão, R C; Araújo, A M; Freitas-Neto, M A; Rosa, M F; Santaella, S T

2009-01-01

The market for coconut water causes environmental problems as it is one of the major agro-industrial solid wastes in some developing countries. With the aim of reusing the coconut husk, Embrapa developed a system for processing this raw material. During the dewatering stage Coconut Husk Liquor (CHL) is generated with chemical oxygen demand (COD) varying from 60 to 70 g/L due to high concentrations of sugars and tannins. The present study evaluated the feasibility of anaerobic treatment of CHL through Anaerobic Toxicity Assay and the operation of a lab-scale Upflow Anaerobic Sludge Blanket (UASB) reactor. Results showed that CHL can be treated through a UASB reactor operating with an OLR that reaches up to 10 kg/m3.d and that is maintained stable during the whole operation. With this operational condition, the removal efficiency was higher than 80% for COD and approximately 78% for total tannins, and biogas production was 20 m3 of biogas or 130 KWh per m3 of CHL. Seventy-five percent of the biogas composition was methane and toxicity tests demonstrated that CHL was not toxic to the methanogenic consortia. Conversely, increasing the concentration of CHL leads to increased methanogenic activity.

Serial completely stirred tank reactors for improving biogas production and substance degradation during anaerobic digestion of corn stover.

PubMed

Li, YuQian; Liu, ChunMei; Wachemo, Akiber Chufo; Yuan, HaiRong; Zou, DeXun; Liu, YanPing; Li, XiuJin

2017-07-01

Several completely stirred tank reactors (CSTR) connected in series for anaerobic digestion of corn stover were investigated in laboratory scale. Serial anaerobic digestion systems operated at a total HRT of 40days, and distribution of HRT are 10+30days (HRT10+30d), 20+20days (HRT20+20d), and 30+10days (HRT30+10d) were compared to a conventional one-step CSTR at the same HRT of 40d. The results showed that in HRT10+30d serial system, the process became very unstable at organic load of 50gTS·L -1 . The HRT20+20d and HRT30+10d serial systems improved methane production by 8.3-14.6% compared to the one-step system in all loads of 50, 70, 90gTS·L -1 . The conversion rates of total solid, cellulose, and hemicellulose were increased in serial anaerobic digestion systems compared to single system. The serial systems showed more stable process performance in high organic load. HRT30+10d system showed the best biogas production and conversions among all systems. Copyright © 2017. Published by Elsevier Ltd.

Anaerobic degradation of benzene in diverse anoxic environments

USGS Publications Warehouse

Kazumi, J.; Caldwell, M.E.; Suflita, J.M.; Lovely, D.R.; Young, L.Y.

1997-01-01

Benzene has often been observed to be resistant to microbial degradation under anoxic conditions. A number of recent studies, however, have demonstrated that anaerobic benzene utilization can occur. This study extends the previous reports of anaerobic benzene degradation to sediments that varied with respect to contamination input, predominant redox condition, and salinity. In spite of differences in methodology, microbial degradation of benzene was noted in slurries constructed with sediments from various geographical locations and range from aquifer sands to fine-grained estuarine muds, under methanogenic, sulfate-reducing, and iron-reducing conditions. In aquifer sediments under methanogenic conditions, benzene loss was concomitant with methane production, and microbial utilization of [14C]benzene yielded 14CO2 and 14CH4. In slurries with estuarine and aquifer sediments under sulfate-reducing conditions, the loss of sulfate in amounts consistent with the stoichiometric degradation of benzene or the conversion of [14C]benzene to 14CO2 indicates that benzene was mineralized. Benzene loss also occurred in the presence of Fe(III) in sediments from freshwater environments. Microbial benzene utilization, however, was not observed under denitrifying conditions. These results indicate that the potential for the anaerobic degradation of benzene, which was once thought to be resistant to non-oxygenase attack, exists in a variety of aquatic sediments from widely distributed locations.

Simulation of anaerobic digestion processes using stochastic algorithm.

PubMed

Palanichamy, Jegathambal; Palani, Sundarambal

2014-01-01

The Anaerobic Digestion (AD) processes involve numerous complex biological and chemical reactions occurring simultaneously. Appropriate and efficient models are to be developed for simulation of anaerobic digestion systems. Although several models have been developed, mostly they suffer from lack of knowledge on constants, complexity and weak generalization. The basis of the deterministic approach for modelling the physico and bio-chemical reactions occurring in the AD system is the law of mass action, which gives the simple relationship between the reaction rates and the species concentrations. The assumptions made in the deterministic models are not hold true for the reactions involving chemical species of low concentration. The stochastic behaviour of the physicochemical processes can be modeled at mesoscopic level by application of the stochastic algorithms. In this paper a stochastic algorithm (Gillespie Tau Leap Method) developed in MATLAB was applied to predict the concentration of glucose, acids and methane formation at different time intervals. By this the performance of the digester system can be controlled. The processes given by ADM1 (Anaerobic Digestion Model 1) were taken for verification of the model. The proposed model was verified by comparing the results of Gillespie's algorithms with the deterministic solution for conversion of glucose into methane through degraders. At higher value of 'τ' (timestep), the computational time required for reaching the steady state is more since the number of chosen reactions is less. When the simulation time step is reduced, the results are similar to ODE solver. It was concluded that the stochastic algorithm is a suitable approach for the simulation of complex anaerobic digestion processes. The accuracy of the results depends on the optimum selection of tau value.

Accelerated anaerobic hydrolysis rates under a combination of intermittent aeration and anaerobic conditions.

PubMed

Jensen, T R; Lastra Milone, T; Petersen, G; Andersen, H R

2017-04-01

Anaerobic hydrolysis in activated return sludge was investigated in laboratory scale experiments to find if intermittent aeration would accelerate anaerobic hydrolysis rates compared to anaerobic hydrolysis rates under strict anaerobic conditions. The intermittent reactors were set up in a 240 h experiment with intermittent aeration (3 h:3 h) in a period of 24 h followed by a subsequent anaerobic period of 24 h in a cycle of 48 h which was repeated five times during the experiment. The anaerobic reactors were kept under strict anaerobic conditions in the same period (240 h). Two methods for calculating hydrolysis rates based on soluble chemical oxygen demand were compared. Two-way analysis of variance with the Bonferroni post-test was performed in order to register any significant difference between reactors with intermittent aeration and strictly anaerobic conditions respectively. The experiment demonstrated a statistically significant difference in favor of the reactors with intermittent aeration showing a tendency towards accelerated anaerobic hydrolysis rates due to application of intermittent aeration. The conclusion of the work is thus that intermittent aeration applied in the activated return sludge process can improve the treatment capacity further in full scale applications.

Engineering and Two-Stage Evolution of a Lignocellulosic Hydrolysate-Tolerant Saccharomyces cerevisiae Strain for Anaerobic Fermentation of Xylose from AFEX Pretreated Corn Stover

PubMed Central

Parreiras, Lucas S.; Breuer, Rebecca J.; Avanasi Narasimhan, Ragothaman; Higbee, Alan J.; La Reau, Alex; Tremaine, Mary; Qin, Li; Willis, Laura B.; Bice, Benjamin D.; Bonfert, Brandi L.; Pinhancos, Rebeca C.; Balloon, Allison J.; Uppugundla, Nirmal; Liu, Tongjun; Li, Chenlin; Tanjore, Deepti; Ong, Irene M.; Li, Haibo; Pohlmann, Edward L.; Serate, Jose; Withers, Sydnor T.; Simmons, Blake A.; Hodge, David B.; Westphall, Michael S.; Coon, Joshua J.; Dale, Bruce E.; Balan, Venkatesh; Keating, David H.; Zhang, Yaoping; Landick, Robert; Gasch, Audrey P.; Sato, Trey K.

2014-01-01

The inability of the yeast Saccharomyces cerevisiae to ferment xylose effectively under anaerobic conditions is a major barrier to economical production of lignocellulosic biofuels. Although genetic approaches have enabled engineering of S. cerevisiae to convert xylose efficiently into ethanol in defined lab medium, few strains are able to ferment xylose from lignocellulosic hydrolysates in the absence of oxygen. This limited xylose conversion is believed to result from small molecules generated during biomass pretreatment and hydrolysis, which induce cellular stress and impair metabolism. Here, we describe the development of a xylose-fermenting S. cerevisiae strain with tolerance to a range of pretreated and hydrolyzed lignocellulose, including Ammonia Fiber Expansion (AFEX)-pretreated corn stover hydrolysate (ACSH). We genetically engineered a hydrolysate-resistant yeast strain with bacterial xylose isomerase and then applied two separate stages of aerobic and anaerobic directed evolution. The emergent S. cerevisiae strain rapidly converted xylose from lab medium and ACSH to ethanol under strict anaerobic conditions. Metabolomic, genetic and biochemical analyses suggested that a missense mutation in GRE3, which was acquired during the anaerobic evolution, contributed toward improved xylose conversion by reducing intracellular production of xylitol, an inhibitor of xylose isomerase. These results validate our combinatorial approach, which utilized phenotypic strain selection, rational engineering and directed evolution for the generation of a robust S. cerevisiae strain with the ability to ferment xylose anaerobically from ACSH. PMID:25222864

Co-digestion of polylactide and kitchen garbage in hyperthermophilic and thermophilic continuous anaerobic process.

PubMed

Wang, Feng; Hidaka, Taira; Tsuno, Hiroshi; Tsubota, Jun

2012-05-01

Two series of two-phase anaerobic systems, consisting of a hyperthermophilic (80°C) reactor and a thermophilic (55°C) reactor, fed with a mixture of kitchen garbage (KG) and polylactide (PLA), was compared with a single-phase thermophilic reactor for the overall performance. The result indicated that ammonia addition under hyperthermophilic condition promoted the transformation of PLA particles to lactic acid. The systems with hyperthermophilic treatment had advantages on PLA transformation and methane conversion ratio to the control system. Under the organic loading rate (OLR) of 10.3 g COD/(L day), the PLA transformation ratios of the two-phase systems were 82.0% and 85.2%, respectively, higher than that of the control system (63.5%). The methane conversion ratios of the two-phase systems were 82.9% and 80.8%, respectively, higher than 70.1% of the control system. The microbial community analysis indicated that hyperthermophilic treatment is easily installed to traditional thermophilic anaerobic digestion plants without inoculation of special bacteria. Copyright © 2012 Elsevier Ltd. All rights reserved.

Anaerobic bacteria

MedlinePlus

Anaerobic bacteria are bacteria that do not live or grow when oxygen is present. In humans, these bacteria ... Brook I. Diseases caused by non-spore-forming anaerobic bacteria. In: Goldman L, Schafer AI, eds. Goldman-Cecil ...

Clostridiumm ljungdahlii, an anaerobic ethanol and acetate producing microorganism

DOEpatents

Gaddy, J.L.; Clausen, E.C.

1992-12-22

A newly discovered microorganism was isolated in a biologically pure culture and designated Clostridium ljungdahlii, having the identifying characteristics of ATCC No. 49587. Cultured in an aqueous nutrient medium under anaerobic conditions, this microorganism is capable of producing ethanol and acetate from CO and H[sub 2]O and/or CO[sub 2] and H[sub 2] in synthesis gas. Under optimal growth conditions, the microorganism produces acetate in preference to ethanol. Conversely, under non-growth conditions, ethanol production is favored over acetate. 3 figs.

Enhancement of anaerobic biodegradability of flower stem wastes with vegetable wastes by co-hydrolysis.

PubMed

Zhang, Bo; He, Pinjing; Lü, Fan; Shao, Liming

2008-01-01

The vegetable wastes and flower stems were co-digested to evaluate the anaerobic hydrolysis performance of difficultly biodegradable organic wastes by introducing readily biodegradable organic wastes. The experiments were carried out in batches. When the vegetable wastes were mixed with the flower stems at the dry weight ratio of 1 to 13, the overall hydrolysis rate increased by 8%, 12%, and 2% according to the carbon, nitrogen, and total solid (TS) conversion rate, respectively. While the dry weight ratio was designed as 1 to 3, there was a respective rise of 5%, 15%, and 4% in the conversion rate of carbon, nitrogen, and TS. The enhancement of anaerobic hydrolysis from the mixed vegetable wastes and flower stems can be attributed to the formation of volatile fatty acids (VFA) and nutrient supplement like nitrogen content. The maximum VFA concentration can achieve 1.7 g/L owing to the rapid acidification of vegetable wastes, loosing the structure of lignocellulose materials. The statistic bivariate analysis revealed that the hydrolysis performance was significantly related to the physical and biochemical compositions of the feeding substrate. Especially, the soluble carbon concentration in the liquid was significantly positively correlated to the concentration of nitrogen and hemicellulose, and negatively correlated to the concentration of carbon and lignocellulose in the feeding substrate, suggesting that the regulation and control of feedstock can have an important influence on the anaerobic hydrolysis of organic wastes.

Anaerobic digestion of municipal solid waste: Utility of process residues as a soil amendment

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

Rivard, C.J.; Nagle, N.J.; Kay, B.D.

1995-12-31

Tuna processing wastes (sludges high in fat, oil, and grease [FOG]) and municipal solid waste (MSW) generated on Tutuila Island, American Samoa, represent an ongoing disposal challenge. The biological conversion of the organic fraction of these wastes to useful products, including methane and fertilizer-grade residue, through anaerobic high-solids digestion is currently in scale-up development. The suitability of the anaerobic digestion residues as a soil amendment was evaluated through extensive chemical analysis and greenhouse studies using corn as an indicator crop. Additionally, native Samoan soil was used to evaluate the specific application rates for the compost. Experiments established that anaerobic residuesmore » increase crop yields in direct proportion to increases in the application rate. Additionally, nutrient saturation was not demonstrated within the range of application rates evaluated for the Samoan soil. Beyond nutrient supplementation, organic residue amendment to Samoan soil imparts enhanced water and nutrient-binding capacities.« less

Application of next-generation sequencing methods for microbial monitoring of anaerobic digestion of lignocellulosic biomass.

PubMed

Bozan, Mahir; Akyol, Çağrı; Ince, Orhan; Aydin, Sevcan; Ince, Bahar

2017-09-01

The anaerobic digestion of lignocellulosic wastes is considered an efficient method for managing the world's energy shortages and resolving contemporary environmental problems. However, the recalcitrance of lignocellulosic biomass represents a barrier to maximizing biogas production. The purpose of this review is to examine the extent to which sequencing methods can be employed to monitor such biofuel conversion processes. From a microbial perspective, we present a detailed insight into anaerobic digesters that utilize lignocellulosic biomass and discuss some benefits and disadvantages associated with the microbial sequencing techniques that are typically applied. We further evaluate the extent to which a hybrid approach incorporating a variation of existing methods can be utilized to develop a more in-depth understanding of microbial communities. It is hoped that this deeper knowledge will enhance the reliability and extent of research findings with the end objective of improving the stability of anaerobic digesters that manage lignocellulosic biomass.

Toxicity and biodegradability of selected N-substituted phenols under anaerobic conditions

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

Donlon, B.; Razo-Flores, E.; Hwu, C.S.

1995-12-31

The anaerobic toxicity and biodegradability of N-substituted aromatics were evaluated in order to obtain information on their ultimate biotreatment. The toxicity of selected N-substituted aromatic compounds toward acetoclastic methanogens in granular sludge was measured in batch assays. This toxicity was highly correlated with compound hydrophobicity, indicating that partitioning into the bacterial membranes was an important factor in the toxicity. However, other factors, such as chemical interactions with key cell components, were suggested to be playing an important role. Nitroaromatic compounds were, on the average, over 300-fold more toxic than their amino-substituted counterparts. This finding suggests that the facile reduction ofmore » nitro-groups known to occur in anaerobic environments would result in a high level of detoxification. To test this hypothesis, continuous lab-scale upward-flow anaerobic sludge bed reactors treating 2-nitrophenol and 4-nitrophenol were established. The 4-nitrophenol was readily converted to the corresponding 4-aminophenol, whereas complete mineralization of 2-nitrophenol via intermediate formation of 2-aminophenol was obtained. These conversions led to a dramatic detoxification of the nitrophenols, because it was feasible to treat the highly toxic nitrophenolics at high organic loading rates.« less

Cometabolic degradation kinetics of TCE and phenol by Pseudomonas putida.

PubMed

Chen, Yan-Min; Lin, Tsair-Fuh; Huang, Chih; Lin, Jui-Che

2008-08-01

Modeling of cometabolic kinetics is important for better understanding of degradation reaction and in situ application of bio-remediation. In this study, a model incorporated cell growth and decay, loss of transformation activity, competitive inhibition between growth substrate and non-growth substrate and self-inhibition of non-growth substrate was proposed to simulate the degradation kinetics of phenol and trichloroethylene (TCE) by Pseudomonas putida. All the intrinsic parameters employed in this study were measured independently, and were then used for predicting the batch experimental data. The model predictions conformed well to the observed data at different phenol and TCE concentrations. At low TCE concentrations (<2 mg l(-1)), the models with or without self-inhibition of non-growth substrate both simulated the experimental data well. However, at higher TCE concentrations (>6 mg l(-1)), only the model considering self-inhibition can describe the experimental data, suggesting that a self-inhibition of TCE was present in the system. The proposed model was also employed in predicting the experimental data conducted in a repeated batch reactor, and good agreements were observed between model predictions and experimental data. The results also indicated that the biomass loss in the degradation of TCE below 2 mg l(-1) can be totally recovered in the absence of TCE for the next cycle, and it could be used for the next batch experiment for the degradation of phenol and TCE. However, for higher concentration of TCE (>6 mg l(-1)), the recovery of biomass may not be as good as that at lower TCE concentrations.

A modeling approach to direct interspecies electron transfer process in anaerobic transformation of ethanol to methane.

PubMed

Liu, Yiwen; Zhang, Yaobin; Zhao, Zhiqiang; Ngo, Huu Hao; Guo, Wenshan; Zhou, Junliang; Peng, Lai; Ni, Bing-Jie

2017-01-01

Recent studies have shown that direct interspecies electron transfer (DIET) plays an important part in contributing to methane production from anaerobic digestion. However, so far anaerobic digestion models that have been proposed only consider two pathways for methane production, namely, acetoclastic methanogenesis and hydrogenotrophic methanogenesis, via indirect interspecies hydrogen transfer, which lacks an effective way for incorporating DIET into this paradigm. In this work, a new mathematical model is specifically developed to describe DIET process in anaerobic digestion through introducing extracellular electron transfer as a new pathway for methane production, taking anaerobic transformation of ethanol to methane as an example. The developed model was able to successfully predict experimental data on methane dynamics under different experimental conditions, supporting the validity of the developed model. Modeling predictions clearly demonstrated that DIET plays an important role in contributing to overall methane production (up to 33 %) and conductive material (i.e., carbon cloth) addition would significantly promote DIET through increasing ethanol conversion rate and methane production rate. The model developed in this work will potentially enhance our current understanding on syntrophic metabolism via DIET.

Modeling anaerobic digestion of aquatic plants by rumen cultures: cattail as an example.

PubMed

Zhao, Bai-Hang; Yue, Zheng-Bo; Ni, Bing-Jie; Mu, Yang; Yu, Han-Qing; Harada, Hideki

2009-04-01

Despite of the significance of the anaerobic digestion of lignocellulosic materials, only a limited number of studies have been carried out to evaluate the lignocellulosic digestion kinetics, and information about the modeling of this process is limited. In this work, a mathematical model, based on the Anaerobic Digestion Model No.1 (ADM1), was developed to describe the anaerobic conversion of lignocellulose-rich aquatic plants, with cattail as an example, by rumen microbes. Cattail was fractionated into slowly hydrolysable fraction (SHF), readily hydrolysable fraction (RHF) and inert fraction in the model. The SHF was hydrolyzed by rumen microbes and resulted in the production of RHF. The SHF and RHF had different hydrolysis rates but both with surface-limiting kinetics. The rumen microbial population diversity, including the cattail-, butyrate-, acetate- and H(2)-degraders, was all incorporated in the model structure. Experiments were carried out to identify the parameters and to calibrate and validate this model. The simulation results match the experimental data, implying that the fractionation of cattail into two biodegradation parts, i.e., SHF and RHF, and modeling their hydrolysis rate with a surface-limiting kinetics were appropriate. The model was capable of simulating the anaerobic biodegradation of cattail by the rumen cultures.

Anaerobic sequencing batch reactor in pilot scale for treatment of tofu industry wastewater

NASA Astrophysics Data System (ADS)

Rahayu, Suparni Setyowati; Purwanto, Budiyono

2015-12-01

The small industry of tofu production process releases the waste water without being processed first, and the wastewater is directly discharged into water. In this study, Anaerobic Sequencing Batch Reactor in Pilot Scale for Treatment of Tofu Industry was developed through an anaerobic process to produce biogas as one kind of environmentally friendly renewable energy which can be developed into the countryside. The purpose of this study was to examine the fundamental characteristics of organic matter elimination of industrial wastewater with small tofu effective method and utilize anaerobic active sludge with Anaerobic Sequencing Bath Reactor (ASBR) to get rural biogas as an energy source. The first factor is the amount of the active sludge concentration which functions as the decomposers of organic matter and controlling selectivity allowance to degrade organic matter. The second factor is that HRT is the average period required substrate to react with the bacteria in the Anaerobic Sequencing Bath Reactor (ASBR).The results of processing the waste of tofu production industry using ASBR reactor with active sludge additions as starter generates cumulative volume of 5814.4 mL at HRT 5 days so that in this study it is obtained the conversion 0.16 L of CH4/g COD and produce biogas containing of CH4: 81.23% and CO2: 16.12%. The wastewater treatment of tofu production using ASBR reactor is able to produce renewable energy that has economic value as well as environmentally friendly by nature.

Anaerobic stabilization and conversion of transformed intermediates of antibiotic pharmaceutical effluent in a fluidized bed reactor.

PubMed

Tamijevendane, S; Saravanane, R; Rajesh, R; Sivacoumar, R

2011-07-01

The formulation and implementation of regulatory standards for the ultimate disposal and reuse of transformed products of antibiotic drugs and solvents have been a pending issue in the waste management of pharmaceutical industries especially in the developing countries like India. A case study has been identified and the current issues in one of the major pharmaceutical industry (manufacturing cephalosporin drugs) located in Chennai, India, has been discussed for the possible implementation of anaerobically transformed intermediates of antibiotic pharmaceutical waste sludge. The objective of the study was to determine the effect of bioaugmentation on the convertibility of anaerobically transformed intermediates of antibiotic pharmaceutical waste sludge into residuals and biocompost. Cephalosporin is a common name refers to cephradine (C16H19N3O4S) and cephalexin (C16H17N3O4S.H2O). Based on the critical examination of results, the industry is looking for the alternatives of either direct disposal of 7-amino-3-deacetoxycephalosporanic acid (7-ADCA) and phenyl acetic acid or for further degradation and disposal, which will essentially require additional cost and maintenance. The present regulatory standard implemented in India does not envisage such disposal alternatives and hence this would invite suggestions and recommendations of the expertise for the possible implementation on the pending issue in the antibiotic based pharmaceutical industries. The presence of cephalosporin increases total strength (Chemical Oxygen Demand) of the effluent and indirectly increases the cost of the treatment. Hence the biotransformation of cephalosporin either alone or in combination with other energetic compounds, offers the potential for an economical and environment friendly disposal alternative for the anaerobically transformed intermediates of antibiotic pharmaceutical waste sludge.

Identification of crude-oil components and microorganisms that cause souring under anaerobic conditions.

PubMed

Hasegawa, R; Toyama, K; Miyanaga, K; Tanji, Y

2014-02-01

Oil souring has important implications with respect to energy resources. Understanding the physiology of the microorganisms that play a role and the biological mechanisms are both important for the maintenance of infrastructure and mitigation of corrosion processes. The objective of this study was to identify crude-oil components and microorganisms in oil-field water that contribute to crude-oil souring. To identify the crude-oil components and microorganisms that are responsible for anaerobic souring in oil reservoirs, biological conversion of crude-oil components under anaerobic conditions was investigated. Microorganisms in oil field water in Akita, Japan degraded alkanes and aromatics to volatile fatty acids (VFAs) under anaerobic conditions, and fermenting bacteria such as Fusibacter sp. were involved in VFA production. Aromatics such as toluene and ethylbenzene were degraded by sulfate-reducing bacteria (Desulfotignum sp.) via the fumarate-addition pathway and not only degradation of VFA but also degradation of aromatics by sulfate-reducing bacteria was the cause of souring. Naphthenic acid and 2,4-xylenol were not converted.

Anaerobic Digestion and its Applications

EPA Science Inventory

Anaerobic digestion is a natural biological process. The initials "AD" may refer to the process of anaerobic digestion, or the built systems of anaerobic digesters. While there are many kinds of digesters, the biology is basically the same for all. Anaerobic digesters are built...

Anaerobic Biodegradation of Detergent Surfactants

PubMed Central

Merrettig-Bruns, Ute; Jelen, Erich

2009-01-01

Detergent surfactants can be found in wastewater in relevant concentrations. Most of them are known as ready degradable under aerobic conditions, as required by European legislation. Far fewer surfactants have been tested so far for biodegradability under anaerobic conditions. The natural environment is predominantly aerobic, but there are some environmental compartments such as river sediments, sub-surface soil layer and anaerobic sludge digesters of wastewater treatment plants which have strictly anaerobic conditions. This review gives an overview on anaerobic biodegradation processes, the methods for testing anaerobic biodegradability, and the anaerobic biodegradability of different detergent surfactant types (anionic, nonionic, cationic, amphoteric surfactants).

[Current clinical significance of anaerobic bacteremia].

PubMed

Jirsa, Roman; Marešová, Veronika; Brož, Zdeněk

2010-10-01

to estimate tje current clinical significance of anaerobic bacteremia in a group of Czech hospitals. this retrospective analysis comprised 8 444 anaerobic blood cultures in patients admitted to four Czech hospitals between 2004 and 2007. in 16 patients, blood cultures yielded significant anaerobic bacteria. Thus, anaerobic bacteremia accounted for less than 2 % of clinically significant bacteremia. Four patients (18 %) died but none of the deaths could be clearly attributable to anaerobic bacteria in the bloodstream. The most common comorbidities predisposing to anaerobic bacteremia and the most frequent sources of infection were similar to those reported by other authors. The majority of anaerobic bacteremia cases were due to gram-negative bacteria, followed by Clostridium perfringens and, surprisingly, Eubacterium spp. (particularly Eubacterium lentum). anaerobic bacteremia remains rare. The comparison of our data with those by other authors suggests that (despite the reported high mortality) the actual clinical significance of anaerobic bacteremia is rather controversial and that the anaerobic bacteremia might not correspond to more serious pathogenic role of the anaerobic bacteria as the source of infection.

Anaerobic oxidation of methane coupled to thiosulfate reduction in a biotrickling filter.

PubMed

Cassarini, Chiara; Rene, Eldon R; Bhattarai, Susma; Esposito, Giovanni; Lens, Piet N L

2017-09-01

Microorganisms from an anaerobic methane oxidizing sediment were enriched with methane gas as the substrate in a biotrickling filter (BTF) using thiosulfate as electron acceptor for 213days. Thiosulfate disproportionation to sulfate and sulfide were the dominating sulfur conversion process in the BTF and the sulfide production rate was 0.5mmoll -1 day -1 . A specific group of sulfate reducing bacteria (SRB), belonging to the Desulforsarcina/Desulfococcus group, was enriched in the BTF. The BTF biomass showed maximum sulfate reduction rate (0.38mmoll -1 day -1 ) with methane as sole electron donor, measured in the absence of thiosulfate in the BTF. Therefore, a BTF fed with thiosulfate as electron acceptor can be used to enrich SRB of the DSS group and activate the inoculum for anaerobic oxidation of methane coupled to sulfate reduction. Copyright © 2017 Elsevier Ltd. All rights reserved.

Treatment of oilfield produced water by anaerobic process coupled with micro-electrolysis.

PubMed

Li, Gang; Guo, Shuhai; Li, Fengmei

2010-01-01

Treatment of oilfield produced water was investigated using an anaerobic process coupled with micro-electrolysis (ME), focusing on changes in chemical oxygen demand (COD) and biodegradability. Results showed that COD exhibited an abnormal change in the single anaerobic system in which it increased within the first 168 hr, but then decreased to 222 mg/L after 360 hr. The biological oxygen demand (five-day) (BODs)/COD ratio of the water increased from 0.05 to 0.15. Hydrocarbons in the wastewater, such as pectin, degraded to small molecules during the hydrolytic acidification process. Comparatively, the effect of ME was also investigated. The COD underwent a slight decrease and the BOD5/COD ratio of the water improved from 0.05 to 0.17 after ME. Removal of COD was 38.3% under the idealized ME conditions (pH 6.0), using iron and active carbon (80 and 40 g/L, respectively). Coupling the anaerobic process with ME accelerated the COD removal ratio (average removal was 53.3%). Gas chromatography/mass spectrometry was used to analyze organic species conversion. This integrated system appeared to be a useful option for the treatment of water produced in oilfields.

Co-metabolic degradation of diazo dye- reactive blue 160 by enriched mixed cultures BDN.

PubMed

Balapure, Kshama H; Jain, Kunal; Chattaraj, Sananda; Bhatt, Nikhil S; Madamwar, Datta

2014-08-30

Mixed cultures BDN (BDN) proficient in decolourizing diazo dye-reactive blue 160 (RB160) consist of eight bacterial strains, was developed through culture enrichment method from soil samples contaminated with anthropogenic activities. The synthrophic interactions of BDN have led to complete decolourization and degradation of RB160 (100mg/L) within 4h along with co-metabolism of yeast extract (0.5%) in minimal medium. BDN microaerophilicaly decolourized even 1500mg/L of RB160 under high saline conditions (20g/L NaCl) at 37°C and pH 7.0. BDN exhibited broad substrate specificity and decolourized 27 structurally different dyes. The reductase enzymes symmetrically cleaved RB160 and oxidative enzymes further metabolised the degraded products and five different intermediates were identified using FTIR, (1)HNMR and GC-MS. The phytotoxicity assay confirmed that intact RB160 was more toxic than dye degraded intermediates. The BDN was able to colonize and decolourized RB160 in soil model system in presence of indigenous miocroflora as well as in sterile soil without any amendment of additional nutrients, which signifies it useful and potential application in bioremediation. Copyright © 2014 Elsevier B.V. All rights reserved.

Anaerobic co-digestion of livestock and vegetable processing wastes: fibre degradation and digestate stability.

PubMed

Molinuevo-Salces, Beatriz; Gómez, Xiomar; Morán, Antonio; García-González, Mari Cruz

2013-06-01

Anaerobic digestion of livestock wastes (swine manure (SM) and poultry litter (PL)) and vegetable processing wastes (VPW) mixtures was evaluated in terms of methane yield, volatile solids removal and lignocellulosic material degradation. Batch experiments were performed with 2% VS (volatile solids) to ensure complete conversion of TVFAs (total volatile fatty acids) and to avoid ammonia inhibition. Experimental methane yields obtained for the mixtures resulted in higher values than those obtained from the sum of the methane yields from the individual components. VPW addition to livestock wastes before anaerobic digestion also resulted in improved VS elimination. In SM-VPW co-digestions, CH4 yield increased from 111 to 244 mL CH4 g VS added(-1), and the percentage of VS removed increased from 50% to 86%. For PL-VPW co-digestions, the corresponding values were increased from 158 to 223 mL CH4 g VS added(-1) and from 70% to 92% VS removed. Hemicelluloses and more than 50% of cellulose were degraded during anaerobic digestion. Thermal analyses indicated that the stabilization of the wastes during anaerobic digestion resulted in significantly less energy being released by digestate samples than fresh samples. Copyright © 2013 Elsevier Ltd. All rights reserved.

Metabolic characterization of anaerobic fungi provides a path forward for bioprocessing of crude lignocellulose

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

Henske, John K.; Wilken, St. Elmo; Solomon, Kevin V.

The conversion of lignocellulose-rich biomass to bio-based chemicals and higher order fuels remains a grand challenge, as single-microbe approaches often cannot drive both deconstruction and chemical production steps. In contrast, consortia based bioprocessing leverages the strengths of different microbes to distribute metabolic loads and achieve process synergy, product diversity, and bolster yields. Here, we describe a biphasic fermentation scheme that combines the lignocellulolytic action of anaerobic fungi isolated from large herbivores with domesticated microbes for bioproduction. When grown in batch culture, anaerobic fungi release excess sugars from both cellulose and crude biomass due to a wealth of highly expressed carbohydratemore » active enzymes (CAZymes), converting as much as 49% of cellulose to free glucose. This sugar-rich hydrolysate readily supports growth of Saccharomyces cerevisiae, which can be engineered to produce a range of value-added chemicals. Further, construction of metabolic pathways from transcriptomic data reveals that anaerobic fungi do not catabolize all sugars that their enzymes hydrolyze from biomass, leaving other carbohydrates such as galactose, arabinose, and mannose available as nutritional links to other microbes in their consortium. Although basal expression of CAZymes in anaerobic fungi is high, it is drastically amplified by cellobiose breakout products encountered during biomass hydrolysis. Overall, these results suggest that anaerobic fungi provide a nutritional benefit to the rumen microbiome, which can be harnessed to design synthetic microbial communities that compartmentalize biomass degradation and bioproduct formation.« less

Enhanced coproduction of hydrogen and methane from cornstalks by a three-stage anaerobic fermentation process integrated with alkaline hydrolysis.

PubMed

Cheng, Xi-Yu; Liu, Chun-Zhao

2012-01-01

A three-stage anaerobic fermentation process including H(2) fermentation I, H(2) fermentation II, methane fermentation was developed for the coproduction of hydrogen and methane from cornstalks. Hydrogen production from cornstalks using direct microbial conversion by Clostridium thermocellum 7072 was markedly enhanced in the two-stage thermophilic hydrogen fermentation process integrated with alkaline treatment. The highest total hydrogen yield from cornstalks in the two-stage fermentation process reached 74.4 mL/g-cornstalk. The hydrogen fermentation effluents and alkaline hydrolyzate were further used for methane fermentation by anaerobic granular sludge, and the total methane yield reached 205.8 mL/g-cornstalk. The total energy recovery in the three-stage anaerobic fermentation process integrated with alkaline hydrolysis reached 70.0%. Copyright © 2011 Elsevier Ltd. All rights reserved.

Anaerobic gut fungi: Advances in isolation, culture, and cellulolytic enzyme discovery for biofuel production.

PubMed

Haitjema, Charles H; Solomon, Kevin V; Henske, John K; Theodorou, Michael K; O'Malley, Michelle A

2014-08-01

Anaerobic gut fungi are an early branching family of fungi that are commonly found in the digestive tract of ruminants and monogastric herbivores. It is becoming increasingly clear that they are the primary colonizers of ingested plant biomass, and that they significantly contribute to the decomposition of plant biomass into fermentable sugars. As such, anaerobic fungi harbor a rich reservoir of undiscovered cellulolytic enzymes and enzyme complexes that can potentially transform the conversion of lignocellulose into bioenergy products. Despite their unique evolutionary history and cellulolytic activity, few species have been isolated and studied in great detail. As a result, their life cycle, cellular physiology, genetics, and cellulolytic metabolism remain poorly understood compared to aerobic fungi. To help address this limitation, this review briefly summarizes the current body of knowledge pertaining to anaerobic fungal biology, and describes progress made in the isolation, cultivation, molecular characterization, and long-term preservation of these microbes. We also discuss recent cellulase- and cellulosome-discovery efforts from gut fungi, and how these interesting, non-model microbes could be further adapted for biotechnology applications. © 2014 Wiley Periodicals, Inc.

Physical Pretreatment Methods for Improving Microalgae Anaerobic Biodegradability.

PubMed

Córdova, Olivia; Passos, Fabiana; Chamy, Rolando

2018-05-01

Microalgae may be a potential feedstock for biogas production through anaerobic digestion. However, this process is limited by the hydrolytic stage, due to the complex and resistant microalgae cell wall components. This fact hinders biomass conversion into biogas, demanding the application of pretreatment techniques for inducing cell damage and/or lysis and organic matter solubilisation. In this study, sonication, thermal, ultrasound, homogeneizer, hydrothermal and steam explosion pretreatments were evaluated in different conditions for comparing their effects on anaerobic digestion performance in batch reactors. The results showed that the highest biomass solubilisation values were reached for steam explosion (65-73%) and ultrasound (33-57%). In fact, only applied energies higher than 220 W or temperatures higher than 80 °C induced cell wall lysis in C. sorokiniana. Nonetheless, the highest methane yields were not correlated to biogas production. Thermal hydrolysis and steam explosion showed lower methane yields in respect to non-pretreated biomass, suggesting the presence of toxic compounds that inhibited the biological process. Accordingly, these pretreatment techniques led to a negative energy balance. The best pretreatment method among the ones evaluated was thermal pretreatment, with four times more energy produced that demanded.

Thermochemical Pretreatment for Anaerobic Digestion of Sorted Waste

NASA Astrophysics Data System (ADS)

Hao, W.; Hongtao, W.

2008-02-01

The effect of alkaline hydrothermal pre-treatment for anaerobic digestion of mechanically-sorted municipal solid waste (MSW) and source-sorted waste was studied. Waste was hydrothermally pre-treated in dilute alkali solution. Hydrolysis product was incubated in 500 ml saline bottle to determine methane potential (MP) under mesospheric anaerobic conditions. Optimum reaction condition obtained in the study is 170 °C at the dose of 4 g NaOH/100 g solid for one hour. Soluble COD was 13936 mg/L and methane yield was 164 ml/g VS for 6 days incubation at optimum conditions. More than 50% biogas increase was achieved over the control, and methane conversion ratio on carbon basis was enhanced to 30.6%. The digestion period was less than 6 days when pre-treatment temperature was above 130 °C. The organic part of sorted waste is mainly constituted of kitchen garbage and leaf. Model kitchen garbage was completely liquidized at 130 °C for one hour and the methane yield was 276 ml/g VS. Addition of alkali enhance hydroxylation rate and methane yield slightly. The biogas potential of leaf could be observed by pre-treatment above 150 °C under alkaline condition.

Control of C/N ratio for butyric acid production from textile wastewater sludge by anaerobic digestion.

PubMed

Fu, Bo; Zhang, Jingjing; Fan, Jinfeng; Wang, Jin; Liu, He

2012-01-01

Increasing textile wastewaters and their biotreatment byproduct-waste activated sludge are serious pollution problems. Butyric acid production from textile wastewater sludge by anaerobic digestion at different C/N ratios was investigated. Adding starch to textile wastewater sludge with a C/N ratio of 30 increased the butyric acid concentration and percentage accounting for total volatile fatty acids (TVFAs) to 21.42 g/L and 81.5%, respectively, as compared with 21.42 g/L and 10.6% of textile wastewater sludge alone. The maximum butyric acid yield (0.45 g/g VS), conversion rate (0.74 g/g VS(digest)) and production rate (2.25 g/L d) was achieved at a C/N ratio of 30. The biological toxicity of textile wastewater sludge also significantly decreased after the anaerobic digestion. The study indicated that the anaerobic co-digestion of textile wastewater sludge and carbohydrate-rich waste with appropriate C/N ratio is possible for butyric acid production.

Microbial Insight into a Pilot-Scale Enhanced Two-Stage High-Solid Anaerobic Digestion System Treating Waste Activated Sludge.

PubMed

Wu, Jing; Cao, Zhiping; Hu, Yuying; Wang, Xiaolu; Wang, Guangqi; Zuo, Jiane; Wang, Kaijun; Qian, Yi

2017-11-30

High solid anaerobic digestion (HSAD) is a rapidly developed anaerobic digestion technique for treating municipal sludge, and has been widely used in Europe and Asia. Recently, the enhanced HSAD process with thermal treatment showed its advantages in both methane production and VS reduction. However, the understanding of the microbial community is still poor. This study investigated microbial communities in a pilot enhanced two-stage HSAD system that degraded waste activated sludge at 9% solid content. The system employed process "thermal pre-treatment (TPT) at 70 °C, thermophilic anaerobic digestion (TAD), and mesophilic anaerobic digestion (MAD)". Hydrogenotrophic methanogens Methanothermobacter spp. dominated the system with relative abundance up to about 100% in both TAD and MAD. Syntrophic acetate oxidation (SAO) bacteria were discovered in TAD, and they converted acetate into H₂ and CO₂ to support hydrogenotrophic methanogenesis. The microbial composition and conversion route of this system are derived from the high solid content and protein content in raw sludge, as well as the operational conditions. This study could facilitate the understanding of the enhanced HSAD process, and is of academic and industrial importance.

Wingate Anaerobic Test peak power and anaerobic capacity classifications for men and women intercollegiate athletes.

PubMed

Zupan, Michael F; Arata, Alan W; Dawson, Letitia H; Wile, Alfred L; Payn, Tamara L; Hannon, Megan E

2009-12-01

The Wingate Anaerobic Test (WAnT) has been established as an effective tool in measuring both muscular power and anaerobic capacity in a 30-second time period; however, there are no published normative tables by which to compare WAnT performance in men and women intercollegiate athletics. The purpose of this study was to develop a classification system for anaerobic peak power and anaerobic capacity for men and women National Collegiate Athletic Association (NCAA) Division I college athletes using the WAnT. A total of 1,585 (1,374 men and 211 women) tests were conducted on athletes ranging from the ages of 18 to 25 years using the WAnT. Absolute and relative peak power and anaerobic capacity data were recorded. One-half standard deviations were used to set up a 7-tier classification system (poor to elite) for these assessments. These classifications can be used by athletes, coaches, and practitioners to evaluate anaerobic peak power and anaerobic capacity in their athletes.

Conversion of (Meth)acrylic acids to methane granular sludge: Initiation by specific anerobic microflora

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

Shtarkman, N.B.; Obraztova, A.Y.; Laurinavichyus, K.S.

1995-03-01

The role of a specific anaerobic microflora in the initiation of degradation of (meth)acrylic acids to methane by granular sludge from a UASB reactor was investigated. Associations of anaerobic bacteria isolated from the anaerobic sludge, which was used for a long time for treatment of wastewater from (meth)acrylate production, were able to realize the initial stage of (meth)acrylic acid decomposition, i.e., a conversion of acrylic and methacrylic acids to propionic and isobutyric acids, respectively. When added to granules, these association played a role of an {open_quotes}initiator{close_quotes} of the degradation process, which was then continued by the granular sludge microflora utilizingmore » propionate and isobutyrate. Some characteristics of the granules adapted to propionate or isobutyrate are presented. The rates of propionate and isobutyrate consumption by adapted granules is, respectively, 21 and 53 times higher than the values obtained for nonadapted granules. A combined use of {open_quotes}initiating{close_quotes} bacteria and adapted granules provided degradation of (meth)acrylic acids with a maximum methane yield. The possibility is discussed of employing the granules, which are adapted to short-chain fatty acids, and the {open_quotes}initiating{close_quotes} bacteria, which accomplish the initial steps of the organic material decomposition to lower fatty acids, for the conversion of various chemical compounds to methane. 10 refs., 3 figs., 2 tabs.« less

Enzymes involved in the anaerobic oxidation of n-alkanes: from methane to long-chain paraffins

PubMed Central

Callaghan, Amy V.

2013-01-01

Anaerobic microorganisms play key roles in the biogeochemical cycling of methane and non-methane alkanes. To date, there appear to be at least three proposed mechanisms of anaerobic methane oxidation (AOM). The first pathway is mediated by consortia of archaeal anaerobic methane oxidizers and sulfate-reducing bacteria (SRB) via “reverse methanogenesis” and is catalyzed by a homolog of methyl-coenzyme M reductase. The second pathway is also mediated by anaerobic methane oxidizers and SRB, wherein the archaeal members catalyze both methane oxidation and sulfate reduction and zero-valent sulfur is a key intermediate. The third AOM mechanism is a nitrite-dependent, “intra-aerobic” pathway described for the denitrifying bacterium, ‘Candidatus Methylomirabilis oxyfera.’ It is hypothesized that AOM proceeds via reduction of nitrite to nitric oxide, followed by the conversion of two nitric oxide molecules to dinitrogen and molecular oxygen. The latter can be used to functionalize the methane via a particulate methane monooxygenase. With respect to non-methane alkanes, there also appear to be novel mechanisms of activation. The most well-described pathway is the addition of non-methane alkanes across the double bond of fumarate to form alkyl-substituted succinates via the putative glycyl radical enzyme, alkylsuccinate synthase (also known as methylalkylsuccinate synthase). Other proposed mechanisms include anaerobic hydroxylation via ethylbenzene dehydrogenase-like enzymes and an “intra-aerobic” denitrification pathway similar to that described for ‘Methylomirabilis oxyfera.’ PMID:23717304

Cultivation of Anaerobic and Facultatively Anaerobic Bacteria from Spacecraft-Associated Clean Rooms▿

PubMed Central

Stieglmeier, Michaela; Wirth, Reinhard; Kminek, Gerhard; Moissl-Eichinger, Christine

2009-01-01

In the course of this biodiversity study, the cultivable microbial community of European spacecraft-associated clean rooms and the Herschel Space Observatory located therein were analyzed during routine assembly operations. Here, we focused on microorganisms capable of growing without oxygen. Anaerobes play a significant role in planetary protection considerations since extraterrestrial environments like Mars probably do not provide enough oxygen for fully aerobic microbial growth. A broad assortment of anaerobic media was used in our cultivation strategies, which focused on microorganisms with special metabolic skills. The majority of the isolated strains grew on anaerobic, complex, nutrient-rich media. Autotrophic microorganisms or microbes capable of fixing nitrogen were also cultivated. A broad range of facultatively anaerobic bacteria was detected during this study and also, for the first time, some strictly anaerobic bacteria (Clostridium and Propionibacterium) were isolated from spacecraft-associated clean rooms. The multiassay cultivation approach was the basis for the detection of several bacteria that had not been cultivated from these special environments before and also led to the discovery of two novel microbial species of Pseudomonas and Paenibacillus. PMID:19363082

Cultivation of anaerobic and facultatively anaerobic bacteria from spacecraft-associated clean rooms.

PubMed

Stieglmeier, Michaela; Wirth, Reinhard; Kminek, Gerhard; Moissl-Eichinger, Christine

2009-06-01

In the course of this biodiversity study, the cultivable microbial community of European spacecraft-associated clean rooms and the Herschel Space Observatory located therein were analyzed during routine assembly operations. Here, we focused on microorganisms capable of growing without oxygen. Anaerobes play a significant role in planetary protection considerations since extraterrestrial environments like Mars probably do not provide enough oxygen for fully aerobic microbial growth. A broad assortment of anaerobic media was used in our cultivation strategies, which focused on microorganisms with special metabolic skills. The majority of the isolated strains grew on anaerobic, complex, nutrient-rich media. Autotrophic microorganisms or microbes capable of fixing nitrogen were also cultivated. A broad range of facultatively anaerobic bacteria was detected during this study and also, for the first time, some strictly anaerobic bacteria (Clostridium and Propionibacterium) were isolated from spacecraft-associated clean rooms. The multiassay cultivation approach was the basis for the detection of several bacteria that had not been cultivated from these special environments before and also led to the discovery of two novel microbial species of Pseudomonas and Paenibacillus.

Conversion of municipal solid wastes to carboxylic acids by thermophilic fermentation.

PubMed

Chan, Wen Ning; Holtzapple, Mark T

2003-11-01

The purpose of this research is to generate carboxylic acids from the biodegradable fraction of municipal solid wastes (MSW) and municipal sewage sludge (MSS) by using a thermophilic (55 degrees C), anaerobic, high-solid fermentation. With terrestrial inocula, the highest total carboxylic acid concentration achieved was 20.5 g/L, the highest conversion obtained was 69%, and the highest acetic acid selectivity was 86.4%. Marine inocula were also used to compare against terrestrial sources. Continuum particle distribution modeling (CPDM) was used to predict the final acid product concentrations and substrate conversions at a wide range of liquid residence times (LRT) and volatile solid loading rates (VSLR). "Maps" showing the product concentration and conversion for various LRT and VSLR were generated from CPDM. The predictions were compared to the experimental results. On average, the difference between the predicted and experimental values were 13% for acid concentration and 10% for conversion. CPDM "maps" show that marine inocula produce higher concentrations than terrestrial inocula.

Integrated bioprocess for conversion of gaseous substrates to liquids

PubMed Central

Hu, Peng; Chakraborty, Sagar; Kumar, Amit; Woolston, Benjamin; Liu, Hongjuan; Emerson, David; Stephanopoulos, Gregory

2016-01-01

In the quest for inexpensive feedstocks for the cost-effective production of liquid fuels, we have examined gaseous substrates that could be made available at low cost and sufficiently large scale for industrial fuel production. Here we introduce a new bioconversion scheme that effectively converts syngas, generated from gasification of coal, natural gas, or biomass, into lipids that can be used for biodiesel production. We present an integrated conversion method comprising a two-stage system. In the first stage, an anaerobic bioreactor converts mixtures of gases of CO2 and CO or H2 to acetic acid, using the anaerobic acetogen Moorella thermoacetica. The acetic acid product is fed as a substrate to a second bioreactor, where it is converted aerobically into lipids by an engineered oleaginous yeast, Yarrowia lipolytica. We first describe the process carried out in each reactor and then present an integrated system that produces microbial oil, using synthesis gas as input. The integrated continuous bench-scale reactor system produced 18 g/L of C16-C18 triacylglycerides directly from synthesis gas, with an overall productivity of 0.19 g⋅L−1⋅h−1 and a lipid content of 36%. Although suboptimal relative to the performance of the individual reactor components, the presented integrated system demonstrates the feasibility of substantial net fixation of carbon dioxide and conversion of gaseous feedstocks to lipids for biodiesel production. The system can be further optimized to approach the performance of its individual units so that it can be used for the economical conversion of waste gases from steel mills to valuable liquid fuels for transportation. PMID:26951649

Biodegradation of chlorinated ethenes at a karst site in middle Tennessee

USGS Publications Warehouse

Byl, Thomas Duane; Williams, Shannon D.

2000-01-01

This report presents results of field and laboratory investigations examining the biodegradation of chlorinated ethenes in a karst aquifer contaminated with trichloroethylene (TCE). The study site, located in Middle Tennessee, was selected because of the presence of TCE degradation byproducts in the karst aquifer and available site hydrologic and chlorinated-ethene information. Additional chemical, biological, and hydrologic data were gathered to evaluate whether the occurrence of TCE degradation byproducts in the karst aquifer was the result of biodegradation within the aquifer or simply transport into the aquifer. Geochemical analysis established that sulfate-reducing conditions, essential for reductive dechlorination of chlorinated solvents, existed in parts of the contaminated karst aquifer. Other areas of the aquifer fluctuated between anaerobic and aerobic conditions and contained compounds associated with cometabolism, such as ethane, methane, ammonia, and dissolved oxygen. A large, diverse bacteria population inhabits the contaminated aquifer. Bacteria known to biodegrade TCE and other chlorinated solvents, such as sulfate-reducers, methanotrophs, and ammonia-oxidizers, were identified from karst-aquifer water using the RNA-hybridization technique. Results from microcosms using raw karst-aquifer water found that aerobic cometabolism and anaerobic reductive-dechlorination degradation processes were possible when appropriate conditions were established in the microcosms. These chemical and biological results provide circumstantial evidence that several biodegradation processes are active in the aquifer. Additional site hydrologic information was developed to determine if appropriate conditions persist long enough in the karst aquifer for these biodegradation processes to be significant. Continuous monitoring devices placed in four wells during the spring of 1998 indicated that pH, specific conductance, dissolved oxygen, and oxidation-reduction potentials

Industrial symbiosis: corn ethanol fermentation, hydrothermal carbonization, and anaerobic digestion.

PubMed

Wood, Brandon M; Jader, Lindsey R; Schendel, Frederick J; Hahn, Nicholas J; Valentas, Kenneth J; McNamara, Patrick J; Novak, Paige M; Heilmann, Steven M

2013-10-01

The production of dry-grind corn ethanol results in the generation of intermediate products, thin and whole stillage, which require energy-intensive downstream processing for conversion into commercial animal feed products. Hydrothermal carbonization of thin and whole stillage coupled with anaerobic digestion was investigated as alternative processing methods that could benefit the industry. By substantially eliminating evaporation of water, reductions in downstream energy consumption from 65% to 73% were achieved while generating hydrochar, fatty acids, treated process water, and biogas co-products providing new opportunities for the industry. Processing whole stillage in this manner produced the four co-products, eliminated centrifugation and evaporation, and substantially reduced drying. With thin stillage, all four co-products were again produced, as well as a high quality animal feed. Anaerobic digestion of the aqueous product stream from the hydrothermal carbonization of thin stillage reduced chemical oxygen demand (COD) by more than 90% and converted 83% of the initial COD to methane. Internal use of this biogas could entirely fuel the HTC process and reduce overall natural gas usage. Copyright © 2013 Wiley Periodicals, Inc.

Improved glycerol to ethanol conversion by E. coli using a metagenomic fragment isolated from an anaerobic reactor.

PubMed

Loaces, Inés; Rodríguez, Cecilia; Amarelle, Vanesa; Fabiano, Elena; Noya, Francisco

2016-10-01

Crude glycerol obtained as a by-product of biodiesel production is a reliable feedstock with the potential to be converted into reduced chemicals with high yields. It has been previously shown that ethanol is the primary product of glycerol fermentation by Escherichia coli. However, few efforts were made to enhance this conversion by means of the expression of heterologous genes with the potential to improve glycerol transport or metabolism. In this study, a fosmid-based metagenomic library constructed from an anaerobic reactor purge sludge was screened for genetic elements that promote the use and fermentation of crude glycerol by E. coli. One clone was selected based on its improved growth rate on this feedstock. The corresponding fosmid, named G1, was fully sequenced (41 kbp long) and the gene responsible for the observed phenotype was pinpointed by in vitro insertion mutagenesis. Ethanol production from both pure and crude glycerol was evaluated using the parental G1 clone harboring the ethanologenic plasmid pLOI297 or the industrial strain LY180 complemented with G1. In mineral salts media containing 50 % (v/v) pure glycerol, ethanol concentrations increased two-fold on average when G1 was present in the cells reaching up to 20 g/L after 24 h fermentation. Similar fermentation experiments were done using crude instead of pure glycerol. With an initial OD620 of 8.0, final ethanol concentrations after 24 h were much higher reaching 67 and 75 g/L with LY180 cells carrying the control fosmid or the G1 fosmid, respectively. This translates into a specific ethanol production rate of 0.39 g h(-1) OD(-1) L(-1).

Bioremediation and phytoremediation: Chlorinated and recalcitrant compounds

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

NONE

1998-12-31

Bioremediation and phytoremediation have progressed, especially with regard to the treatment of hydrocarbon-contaminated sites. Sites contaminated with chlorinated and recalcitrant compounds have proven more resistant to these approaches, but exciting progress is being made both in the laboratory and in the field. This book brings together the latest breakthrough thinking and results in bioremediation, with chapters on cometabolic processes, aerobic and anaerobic mechanisms, biological reductive dechlorination processes, bioaugmentation, biomonitoring, and phytoremediation of recalcitrant organic compounds.

[Achievement of Sulfate-Reducing Anaerobic Ammonium Oxidation Reactor Started with Nitrate-Reducting Anaerobic Ammonium Oxidation].

PubMed

Liu, Zheng-chuan; Yuan, Lin-jiang; Zhou, Guo-biao; Li, Jing

2015-09-01

The transformation of nitrite-reducing anaerobic ammonium oxidation to sulfate-reducing anaerobic ammonium oxidation in an UASB was performed and the changes in microbial community were studied. The result showed that the sulfate reducing anaerobic ammonium oxidation process was successfully accomplished after 177 days' operation. The removal rate of ammonium nitrogen and sulfate were up to 58. 9% and 15. 7%, the removing load of ammonium nitrogen and sulfate were 74. 3 mg.(L.d)-1 and 77. 5 mg.(L.d)-1 while concentration of ammonium nitrogen and sulfate of influent were 130 mg.(L.d)-1 and 500 mg.(L.d)-1, respectively. The lost nitrogen and sulphur was around 2 in molar ratio. The pH value of the effluent was lower than that of the influent. Instead of Candidatus brocadia in nitrite reducing anaerobic ammonium oxidation granular sludge, Bacillus benzoevorans became the dominant species in sulfate reducing anaerobic ammonium oxidation sludge. The dominant bacterium in the two kinds of anaerobic ammonium oxidation process is different. Our results imply that the two anaerobic ammonium oxidation processes are carried out by different kind of bacterium.

Linking Microbial Community Structure and Function During the Acidified Anaerobic Digestion of Grass

PubMed Central

Joyce, Aoife; Ijaz, Umer Z.; Nzeteu, Corine; Vaughan, Aoife; Shirran, Sally L.; Botting, Catherine H.; Quince, Christopher; O’Flaherty, Vincent; Abram, Florence

2018-01-01

Harvesting valuable bioproducts from various renewable feedstocks is necessary for the critical development of a sustainable bioeconomy. Anaerobic digestion is a well-established technology for the conversion of wastewater and solid feedstocks to energy with the additional potential for production of process intermediates of high market values (e.g., carboxylates). In recent years, first-generation biofuels typically derived from food crops have been widely utilized as a renewable source of energy. The environmental and socioeconomic limitations of such strategy, however, have led to the development of second-generation biofuels utilizing, amongst other feedstocks, lignocellulosic biomass. In this context, the anaerobic digestion of perennial grass holds great promise for the conversion of sustainable renewable feedstock to energy and other process intermediates. The advancement of this technology however, and its implementation for industrial applications, relies on a greater understanding of the microbiome underpinning the process. To this end, microbial communities recovered from replicated anaerobic bioreactors digesting grass were analyzed. The bioreactors leachates were not buffered and acidic pH (between 5.5 and 6.3) prevailed at the time of sampling as a result of microbial activities. Community composition and transcriptionally active taxa were examined using 16S rRNA sequencing and microbial functions were investigated using metaproteomics. Bioreactor fraction, i.e., grass or leachate, was found to be the main discriminator of community analysis across the three molecular level of investigation (DNA, RNA, and proteins). Six taxa, namely Bacteroidia, Betaproteobacteria, Clostridia, Gammaproteobacteria, Methanomicrobia, and Negativicutes accounted for the large majority of the three datasets. The initial stages of grass hydrolysis were carried out by Bacteroidia, Gammaproteobacteria, and Negativicutes in the grass biofilms, in addition to Clostridia in the

Enrichment of anaerobic syngas-converting bacteria from thermophilic bioreactor sludge.

PubMed

Alves, Joana I; Stams, Alfons J M; Plugge, Caroline M; Alves, M Madalena; Sousa, Diana Z

2013-12-01

Thermophilic (55 °C) anaerobic microbial communities were enriched with a synthetic syngas mixture (composed of CO, H2 , and CO2 ) or with CO alone. Cultures T-Syn and T-CO were incubated and successively transferred with syngas (16 transfers) or CO (9 transfers), respectively, with increasing CO partial pressures from 0.09 to 0.88 bar. Culture T-Syn, after 4 successive transfers with syngas, was also incubated with CO and subsequently transferred (9 transfers) with solely this substrate - cultures T-Syn-CO. Incubation with syngas and CO caused a rapid decrease in the microbial diversity of the anaerobic consortium. T-Syn and T-Syn-CO showed identical microbial composition and were dominated by Desulfotomaculum and Caloribacterium species. Incubation initiated with CO resulted in the enrichment of bacteria from the genera Thermincola and Thermoanaerobacter. Methane was detected in the first two to three transfers of T-Syn, but production ceased afterward. Acetate was the main product formed by T-Syn and T-Syn-CO. Enriched T-CO cultures showed a two-phase conversion, in which H2 was formed first and then converted to acetate. This research provides insight into how thermophilic anaerobic communities develop using syngas/CO as sole energy and carbon source can be steered for specific end products and subsequent microbial synthesis of chemicals. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

A novel mode of lactate metabolism in strictly anaerobic bacteria.

PubMed

Weghoff, Marie Charlotte; Bertsch, Johannes; Müller, Volker

2015-03-01

Lactate is a common substrate for major groups of strictly anaerobic bacteria, but the biochemistry and bioenergetics of lactate oxidation is obscure. The high redox potential of the pyruvate/lactate pair of E0 ' = -190 mV excludes direct NAD(+) reduction (E0 ' = -320 mV). To identify the hitherto unknown electron acceptor, we have purified the lactate dehydrogenase (LDH) from the strictly anaerobic, acetogenic bacterium Acetobacterium woodii. The LDH forms a stable complex with an electron-transferring flavoprotein (Etf) that exhibited NAD(+) reduction only when reduced ferredoxin (Fd(2-) ) was present. Biochemical analyses revealed that the LDH/Etf complex of A. woodii uses flavin-based electron confurcation to drive endergonic lactate oxidation with NAD(+) as oxidant at the expense of simultaneous exergonic electron flow from reduced ferredoxin (E0 ' ≈ -500 mV) to NAD(+) according to: lactate + Fd(2-)  + 2 NAD(+)  → pyruvate + Fd + 2 NADH. The reduced Fd(2-) is regenerated from NADH by a sequence of events that involves conversion of chemical (ATP) to electrochemical ( Δ μ ˜ Na + ) and finally redox energy (Fd(2-) from NADH) via reversed electron transport catalysed by the Rnf complex. Inspection of genomes revealed that this metabolic scenario for lactate oxidation may also apply to many other anaerobes. © 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.

Livestock Anaerobic Digester Database

EPA Pesticide Factsheets

The Anaerobic Digester Database provides basic information about anaerobic digesters on livestock farms in the United States, organized in Excel spreadsheets. It includes projects that are under construction, operating, or shut down.

Microbial Insight into a Pilot-Scale Enhanced Two-Stage High-Solid Anaerobic Digestion System Treating Waste Activated Sludge

PubMed Central

Wu, Jing; Cao, Zhiping; Hu, Yuying; Wang, Xiaolu; Wang, Guangqi; Zuo, Jiane; Wang, Kaijun; Qian, Yi

2017-01-01

High solid anaerobic digestion (HSAD) is a rapidly developed anaerobic digestion technique for treating municipal sludge, and has been widely used in Europe and Asia. Recently, the enhanced HSAD process with thermal treatment showed its advantages in both methane production and VS reduction. However, the understanding of the microbial community is still poor. This study investigated microbial communities in a pilot enhanced two-stage HSAD system that degraded waste activated sludge at 9% solid content. The system employed process “thermal pre-treatment (TPT) at 70 °C, thermophilic anaerobic digestion (TAD), and mesophilic anaerobic digestion (MAD)”. Hydrogenotrophic methanogens Methanothermobacter spp. dominated the system with relative abundance up to about 100% in both TAD and MAD. Syntrophic acetate oxidation (SAO) bacteria were discovered in TAD, and they converted acetate into H2 and CO2 to support hydrogenotrophic methanogenesis. The microbial composition and conversion route of this system are derived from the high solid content and protein content in raw sludge, as well as the operational conditions. This study could facilitate the understanding of the enhanced HSAD process, and is of academic and industrial importance. PMID:29189754

BadR and BadM Proteins Transcriptionally Regulate Two Operons Needed for Anaerobic Benzoate Degradation by Rhodopseudomonas palustris

PubMed Central

Hirakawa, Hidetada; Hirakawa, Yuko; Greenberg, E. Peter

2015-01-01

The bacterium Rhodopseudomonas palustris grows with the aromatic acid benzoate and the alicyclic acid cyclohexanecarboxylate (CHC) as sole carbon sources. The enzymatic steps in an oxygen-independent pathway for CHC degradation have been elucidated, but it was unknown how the CHC operon (badHI aliAB badK) encoding the enzymes for CHC degradation was regulated. aliA and aliB encode enzymes for the conversion of CHC to cyclohex-1-enecarboxyl–coenzyme A (CHene-CoA). At this point, the pathway for CHC degradation merges with the pathway for anaerobic benzoate degradation, as CHene-CoA is an intermediate in both degradation pathways. Three enzymes, encoded by badK, badH, and badI, prepare and cleave the alicyclic ring of CHene-CoA to yield pimelyl-CoA. Here, we show that the MarR transcription factor family member, BadR, represses transcription of the CHC operon by binding near the transcription start site of badH. 2-Ketocyclohexane-1-carboxyl–CoA, an intermediate of CHC and benzoate degradation, interacts with BadR to abrogate repression. We also present evidence that the transcription factor BadM binds to the promoter of the badDEFGAB (Bad) operon for the anaerobic conversion of benzoate to CHene-CoA to repress its expression. Contrary to previous reports, BadR does not appear to control expression of the Bad operon. These data enhance our view of the transcriptional regulation of anaerobic benzoate degradation by R. palustris. PMID:25888170

UV-C mutagenesis of Kluyveromyces marxianus NRRL Y-1109 strain for improved anaerobic growth at elevated temperature on pentose and hexose sugars

USDA-ARS?s Scientific Manuscript database

More robust industrial yeast strains from Kluyveromyces marxianus NRRL Y-1109 and have been produced using UV-C irradiation specifically for anaerobic conversion of lignocellulosic sugar streams to fuel ethanol at elevated temperature (45°C). This type of random mutagenesis offers the possibility o...

Comparative assessment of single-stage and two-stage anaerobic digestion for the treatment of thin stillage.

PubMed

Nasr, Noha; Elbeshbishy, Elsayed; Hafez, Hisham; Nakhla, George; El Naggar, M Hesham

2012-05-01

A comparative evaluation of single-stage and two-stage anaerobic digestion processes for biomethane and biohydrogen production using thin stillage was performed to assess the impact of separating the acidogenic and methanogenic stages on anaerobic digestion. Thin stillage, the main by-product from ethanol production, was characterized by high total chemical oxygen demand (TCOD) of 122 g/L and total volatile fatty acids (TVFAs) of 12 g/L. A maximum methane yield of 0.33 L CH(4)/gCOD(added) (STP) was achieved in the two-stage process while a single-stage process achieved a maximum yield of only 0.26 L CH(4)/gCOD(added) (STP). The separation of acidification stage increased the TVFAs to TCOD ratio from 10% in the raw thin stillage to 54% due to the conversion of carbohydrates into hydrogen and VFAs. Comparison of the two processes based on energy outcome revealed that an increase of 18.5% in the total energy yield was achieved using two-stage anaerobic digestion. Copyright © 2012 Elsevier Ltd. All rights reserved.

Economic viability of anaerobic digestion

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

Wellinger, A.

1996-01-01

The industrial application of anaerobic digestion is a relatively new, yet proven waste treatment technology. Anaerobic digestion reduces and upgrades organic waste, and is a good way to control air pollution as it reduces methane and nitrous gas emissions. For environmental and energy considerations, anaerobic digestion is a nearly perfect waste treatment process. However, its economic viability is still in question. A number of parameters - type of waste (solid or liquid), digester system, facility size, product quality and end use, environmental requirements, cost of alternative treatments (including labor), and interest rates - define the investment and operating costs ofmore » an anaerobic digestion facility. Therefore, identical facilities that treat the same amount and type of waste may, depending on location, legislation, and end product characteristics, reveal radically different costs. A good approach for evaluating the economics of anaerobic digestion is to compare it to treatment techniques such as aeration or conventional sewage treatment (for industrial wastewater), or composting and incineration (for solid organic waste). For example, the cost (per ton of waste) of in-vessel composting with biofilters is somewhat higher than that of anaerobic digestion, but the investment costs 1 1/2 to 2 times more than either composting or anaerobic digestion. Two distinct advantages of anaerobic digestion are: (1) it requires less land than either composting or incinerating, which translates into lower costs and milder environmental and community impacts (especially in densely populated areas); and (2) it produces net energy, which can be used to operate the facility or sold to nearby industries.« less

Effect of ferrihydrite biomineralization on methanogenesis in an anaerobic incubation from paddy soil

NASA Astrophysics Data System (ADS)

Zhuang, Li; Xu, Jielong; Tang, Jia; Zhou, Shungui

2015-05-01

Microbial reduction of Fe(III) can be one of the major factors controlling methane production from anaerobic sedimentary environments, such as paddy soils and wetlands. Although secondary iron mineralization following Fe(III) reduction is a process that occurs naturally over time, it has not yet been considered in methanogenic systems. This study performed a long-term anaerobic incubation of a paddy soil and ferrihydrite-supplemented soil cultures to investigate methanogenesis during ferrihydrite biomineralization. The results revealed that the long-term effect of ferrihydrite on methanogenesis may be enhancement rather than suppression documented in previous studies. During initial microbial ferrihydrite reduction, methanogenesis was suppressed; however, the secondary minerals of magnetite formation was simultaneous with facilitated methanogenesis in terms of average methane production rate and acetate utilization rate. In the phase of magnetite formation, microbial community analysis revealed a strong stimulation of the bacterial Geobacter, Bacillus, and Sedimentibacter and the archaeal Methanosarcina in the ferrihydrite-supplemented cultures. Direct electric syntrophy between Geobacter and Methanosarcina via conductive magnetite is the plausible mechanism for methanogenesis acceleration along with magnetite formation. Our data suggested that a change in iron mineralogy might affect the conversion of anaerobic organic matter to methane and might provide a fresh perspective on the mitigation of methane emissions from paddy soils by ferric iron fertilization.

Sludge accumulation and conversion to methane in a septic tank treating domestic wastewater or black water.

PubMed

Elmitwalli, Tarek

2013-01-01

Although the septic tank is the most applied on-site system for wastewater pre-treatment, limited research has been performed to determine sludge accumulation and biogas production in the tank. Therefore a dynamic mathematical model based on the Anaerobic Digestion Model No. 1 (ADM1) was developed for anaerobic digestion of the accumulated sludge in a septic tank treating domestic wastewater or black water. The results showed that influent chemical oxygen demand (COD) concentration and hydraulic retention time (HRT) of the tank mainly control the filling time with sludge, while operational temperature governs characteristics of the accumulated sludge and conversion to methane. For obtaining stable sludge and high conversion, the tank needs to be operated for a period more than a year without sludge wasting. Maximum conversion to methane in the tank is about 50 and 60% for domestic wastewater and black water, respectively. The required period for sludge wasting depends on the influent COD concentration and the HRT, while characteristics of the wasted sludge are affected by operational temperature followed by the influent COD concentration and the HRT. Sludge production from the tank ranges between 0.19 to 0.22 and 0.13 to 0.15 L/(person.d), for the domestic wastewater and black water, respectively.

Can hydrothermal pretreatment improve anaerobic digestion for biogas from lignocellulosic biomass?

PubMed

Wang, Dou; Shen, Fei; Yang, Gang; Zhang, Yanzong; Deng, Shihuai; Zhang, Jing; Zeng, Yongmei; Luo, Tao; Mei, Zili

2018-02-01

Hydrothermally-pretreated rice straw (HPRS) from various pretreatment temperatures was anaerobically-digested in whole slurry. Results indicated promoting pretreatment temperature significantly deconstructed rice straw, and facilitated the conversion of insoluble fractions to soluble fractions. Although 306.6 mL/g TS biogas was maximally yielded in HPRS-90 and HPRS-180, respectively, via digestion in whole slurry, it was only 3% promotion compared to the unpretreated rice straw. HPRS-210 yielded 208.5 mL/g TS biogas, which was 30% reduction with longer lag period of 19.8 d, suggesting serious inhibitions happened. Through slightly increasing organic loading, more serious acidification and reduction on biogas yield, especially at higher pretreatment temperatures, indicated the soluble fractions controlled digestion performances. Pearson correlation analysis suggested negative relationship existed between methane yield and the soluble fractions including soluble carbohydrates, formic acid and furfural. Hydrothermal pretreatment, especially at higher temperature, did not improve anaerobic digestion, thereby, was not recommended, however, lower temperature can be considered potentially. Copyright © 2017 Elsevier Ltd. All rights reserved.

Anaerobic thermophilic culture

DOEpatents

Ljungdahl, Lars G.; Wiegel, Jurgen K. W.

1981-01-01

A newly discovered thermophilic anaerobe is described that was isolated in a biologically pure culture and designated Thermoanaerobacter ethanolicus ATCC 3/550. T. Ethanolicus is cultured in aqueous nutrient medium under anaerobic, thermophilic conditions and is used in a novel process for producing ethanol by subjecting carbohydrates, particularly the saccharides, to fermentation action of the new microorganism in a biologically pure culture.

Problems Caused by Microbes and Treatment Strategies Anaerobic Hydrocarbon Biodegradation and Biocorrosion: A Case Study

NASA Astrophysics Data System (ADS)

Suflita, Joseph M.; Duncan, Kathleen E.

The anaerobic biodegradation of petroleum hydrocarbons is important for the intrinsic remediation of spilt fuels (Gieg and Suflita, 2005), for the conversion of hydrocarbons to clean burning natural gas (Gieg et al., 2008; Jones et al., 2008) and for the fundamental cycling of carbon on the planet (Caldwell et al., 2008). However, the same process has also been implicated in a host of difficult problems including reservoir souring (Jack and Westlake, 1995), oil viscosity alteration (Head et al., 2003), compromised equipment performance and microbiologically influenced corrosion (Duncan et al., 2009). Herein, we will focus on the role of anaerobic microbial communities in catalysing biocorrosion activities in oilfield facilities. Biocorrosion is a costly problem that remains relatively poorly understood. Understanding of the underlying mechanisms requires reliable information on the carbon and energy sources supporting biofilm microorganisms capable of catalysing such activities.

Modeling of Anaerobic Digestion with a Focus on Estimation of Hydrolysis Constants at 35, 55, and 60 °C.

PubMed

Haghighatafshar, Salar; Ossiansson, Elin; Koch, Konrad; Kjerstadius, Hamse; Jansen, Jes la Cour; Davidsson, Åsa

2015-07-01

Hydrolysis constants of mixed sludge at 35, 55, and 60 °C were found to be 0.32, 0.44, and 0.50 1/d, respectively, in pilot-scale, semicontinuously operated anaerobic digesters. The hydrolysis constants and estimated chemical oxygen demand fractions in the feed were introduced to a mathematical model for anaerobic digestion published by Siegrist et al. (2002), which is similar to Anaerobic Digestion Model No. 1. First-order and Monod-type kinetics were tested for estimation of hydrolysis constants. The applied kinetics were found to affect the outcome of the regression study. Moreover, the free ammonia inhibition model was excluded for both propionate oxidation and acetate conversion, thanks to the apparent acclimatized biomass. No substantial accumulation of volatile fatty acids was observed in the reactors at 35, 55, and 60 °C, corresponding to free ammonia nitrogen concentrations of about 20, 110, and 130 g N/m³, respectively.

Novel Hydrogen Production Systems Operative at Thermodynamic Extremes

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

Gunsalus, Robert

2012-11-30

We have employed a suite of molecular, bioinformatics, and biochemical tools to interrogate the thermodynamically limiting steps of H{sub 2} production from fatty acids in syntrophic communities. We also developed a new microbial model system that generates high H{sub 2} concentrations (over 17% of the gas phase) with high H{sub 2} yields of over 3 moles H{sub 2} per mole glucose. Lastly, a systems-based study of biohydrogen production in model anaerobic consortia was performed to begin identifying key regulated steps as a precursor to modeling co-metabolism. The results of these studies significantly expand our ability to predict and model systemsmore » for H{sub 2} production in novel anaerobes that are currently very poorly documented or understood.« less

Paradoxical anaerobism in desert pupfish.

PubMed

Heuton, Matt; Ayala, Luis; Burg, Chris; Dayton, Kyle; McKenna, Ken; Morante, Aldo; Puentedura, Georgina; Urbina, Natasha; Hillyard, Stanley; Steinberg, Spencer; van Breukelen, Frank

2015-12-01

In order to estimate metabolic demands of desert pupfish for conservation purposes, we measured oxygen consumption in fish acclimated to the ecologically relevant temperatures of 28 or 33°C. For these experiments, we used fish derived from a refuge population of Devils Hole pupfish (Cyprinodon diabolis). Measurement of routine oxygen consumption (V̇O2,routine) revealed some 33°C-acclimated fish (10% of 295 assayed fish) periodically exhibited periods of no measurable oxygen consumption despite available ambient oxygen tensions that were above the critical PO2. We call this phenomenon paradoxical anaerobism. The longest observed continuous bout with no oxygen consumption was 149 min, although typical bouts were much shorter. Fish maintained normal posture and ventilation rate (>230 ventilations per minute) during paradoxical anaerobism. Fish rarely demonstrated a compensatory increase in oxygen use following a period of paradoxical anaerobism. In contrast, only one out of 262 sampled fish acclimated at 28°C spontaneously demonstrated paradoxical anaerobism. Muscle lactate concentration was not elevated during periods of paradoxical anaerobism. However, the amount of ethanol released by the 33°C-acclimated fish was 7.3 times greater than that released by the 28°C acclimation group, suggesting ethanol may be used as an alternative end product of anaerobic metabolism. Exposure to exogenous ethanol, in concentrations as low as 0.1%, produced periods of paradoxical anaerobism even in 28°C-acclimated fish. © 2015. Published by The Company of Biologists Ltd.

Anaerobic co-digestion of sewage sludge and food waste using temperature-phased anaerobic digestion process.

PubMed

Kim, H W; Han, S K; Shin, H S

2004-01-01

This study was performed to overcome the low efficiency of anaerobic digestion of sewage sludge and food waste by combining temperature-phased digestion, sequencing batch operation, and co-digestion technology. It was demonstrated that the temperature-phased anaerobic sequencing batch reactor (TPASBR) system for the co-digestion of sewage sludge and food waste resulted in enhanced volatile solids (VS) reduction and methane production rate. At the organic loading rate (OLR) of 2.7 g VS/l/d, the TPASBR system showed the higher VS reduction (61.3%), CH4 yield (0.28 l/g VS(added)) and CH4 production rate (0.41 l CH4/l/d) than those (0.29 l CH4/l/d) of the mesophilic two-stage ASBR (MTSASBR). In the specific methanogenic activity (SMA) tests on thermophilic biomass of the TPASBR system, the average SMA of acetate (93 ml CH4/gVSS/d) was much higher than those of propionate (46 ml CH4/g VSS/d) and butyrate (76 ml CH4/g VSS/d). Also, higher specific hydrolytic activity (SHA, 217 mg COD/g VSS/d) of the biomass supported fast hydrolysis under thermophilic conditions. The track study revealed that the most active period of the 24 h cycle was between 6 and 12 h. The enhanced performance of the TPASBR system could be attributed to longer solids retention time, fast hydrolysis, higher CH4 conversion rate, and balanced nutrient condition of co-substrate. It was verified that this combination could be a promising and practical alternative for the simultaneous recycling of two types of organic fraction of municipal solid waste (OFMSW) with high stability.

Off-Ice Anaerobic Power Does Not Predict On-Ice Repeated Shift Performance in Hockey.

PubMed

Peterson, Ben J; Fitzgerald, John S; Dietz, Calvin C; Ziegler, Kevin S; Baker, Sarah E; Snyder, Eric M

2016-09-01

Peterson, BJ, Fitzgerald, JS, Dietz, CC, Ziegler, KS, Baker, SE, and Snyder, EM. Off-ice anaerobic power does not predict on-ice repeated shift performance in hockey. J Strength Cond Res 30(9): 2375-2381, 2016-Anaerobic power is a significant predictor of acceleration and top speed in team sport athletes. Historically, these findings have been applied to ice hockey although recent research has brought their validity for this sport into question. As ice hockey emphasizes the ability to repeatedly produce power, single bout anaerobic power tests should be examined to determine their ability to predict on-ice performance. We tested whether conventional off-ice anaerobic power tests could predict on-ice acceleration, top speed, and repeated shift performance. Forty-five hockey players, aged 18-24 years, completed anthropometric, off-ice, and on-ice tests. Anthropometric and off-ice testing included height, weight, body composition, vertical jump, and Wingate tests. On-ice testing consisted of acceleration, top speed, and repeated shift fatigue tests. Vertical jump (VJ) (r = -0.42; r = -0.58), Wingate relative peak power (WRPP) (r = -0.32; r = -0.43), and relative mean power (WRMP) (r = -0.34; r = -0.48) were significantly correlated (p ≤ 0.05) to on-ice acceleration and top speed, respectively. Conversely, none of the off-ice tests correlated with on-ice repeated shift performance, as measured by first gate, second gate, or total course fatigue; VJ (r = 0.06; r = 0.13; r = 0.09), WRPP (r = 0.06; r = 0.14; r = 0.10), or WRMP (r = -0.10; r = -0.01; r = -0.01). Although conventional off-ice anaerobic power tests predict single bout on-ice acceleration and top speed, they neither predict the repeated shift ability of the player, nor are good markers for performance in ice hockey.

Anaerobic prosthetic joint infection.

PubMed

Shah, Neel B; Tande, Aaron J; Patel, Robin; Berbari, Elie F

2015-12-01

In an effort to improve mobility and alleviate pain from degenerative and connective tissue joint disease, an increasing number of individuals are undergoing prosthetic joint replacement in the United States. Joint replacement is a highly effective intervention, resulting in improved quality of life and increased independence [1]. By 2030, it is predicted that approximately 4 million total hip and knee arthroplasties will be performed yearly in the United States [2]. One of the major complications associated with this procedure is prosthetic joint infection (PJI), occurring at a rate of 1-2% [3-7]. In 2011, the Musculoskeletal Infectious Society created a unifying definition for prosthetic joint infection [8]. The following year, the Infectious Disease Society of America published practice guidelines that focused on the diagnosis and management of PJI. These guidelines focused on the management of commonly encountered organisms associated with PJI, including staphylococci, streptococci and select aerobic Gram-negative bacteria. However, with the exception of Propionibacterium acnes, management of other anaerobic organisms was not addressed in these guidelines [1]. Although making up approximately 3-6% of PJI [9,10], anaerobic microorganisms cause devastating complications, and similar to the more common organisms associated with PJI, these bacteria also result in significant morbidity, poor outcomes and increased health-care costs. Data on diagnosis and management of anaerobic PJI is mostly derived from case reports, along with a few cohort studies [3]. There is a paucity of published data outlining factors associated with risks, diagnosis and management of anaerobic PJI. We therefore reviewed available literature on anaerobic PJI by systematically searching the PubMed database, and collected data from secondary searches to determine information on pathogenesis, demographic data, clinical features, diagnosis and management. We focused our search on five commonly

High-rate two-phase process for the anaerobic degradation of cellulose, employing rumen microorganisms for an efficient acidogenesis

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

Gijzen, H.J.; Zwart, K.B.; Verhagen, F.J.M.

1988-04-05

A novel two-stage anaerobic process for the microbial conversion of cellulose into biogas has been developed. In the first phase, a mixed population of rumen bacteria and ciliates was used in the hydrolysis and fermentation of cellulose. The volatile fatty acids (VFA) produced in this acidogenic reactor were subsequently converted into biogas in a UASB-type methanogenic reactor. A stepwise increase of the loading rate from 11.9 to 25.8 g volatile solids/L reactor volume/day (g VS/L/day) did not affect the degradation efficiency in the acidogenic reactor, whereas the methanogenic reactor appeared to be overloaded at the highest loading rate. Cellulose digestionmore » was almost complete at all loading rates applied. The two-stage anaerobic process was also tested with a closed fluid circuit. In this instance total methane production was 0.438 L CH/sub 4//g VS added, which is equivalent to 98% of the theoretical value. The application of rumen microorganisms in combination with a high-rate methane reactor is proposed as a means of efficient anaerobic degradation of cellulosic residues to methane. Because this newly developed two-phase system is based on processes and microorganisms from the ruminant, it will be referred to as Rumen Derived Anaerobic Digestion (RUDAD)-process.« less

Biological conversion assay using Clostridium phytofermentans to estimate plant feedstock quality.

PubMed

Lee, Scott J; Warnick, Thomas A; Pattathil, Sivakumar; Alvelo-Maurosa, Jesús G; Serapiglia, Michelle J; McCormick, Heather; Brown, Virginia; Young, Naomi F; Schnell, Danny J; Smart, Lawrence B; Hahn, Michael G; Pedersen, Jeffrey F; Leschine, Susan B; Hazen, Samuel P

2012-02-08

There is currently considerable interest in developing renewable sources of energy. One strategy is the biological conversion of plant biomass to liquid transportation fuel. Several technical hurdles impinge upon the economic feasibility of this strategy, including the development of energy crops amenable to facile deconstruction. Reliable assays to characterize feedstock quality are needed to measure the effects of pre-treatment and processing and of the plant and microbial genetic diversity that influence bioconversion efficiency. We used the anaerobic bacterium Clostridium phytofermentans to develop a robust assay for biomass digestibility and conversion to biofuels. The assay utilizes the ability of the microbe to convert biomass directly into ethanol with little or no pre-treatment. Plant samples were added to an anaerobic minimal medium and inoculated with C. phytofermentans, incubated for 3 days, after which the culture supernatant was analyzed for ethanol concentration. The assay detected significant differences in the supernatant ethanol from wild-type sorghum compared with brown midrib sorghum mutants previously shown to be highly digestible. Compositional analysis of the biomass before and after inoculation suggested that differences in xylan metabolism were partly responsible for the differences in ethanol yields. Additionally, we characterized the natural genetic variation for conversion efficiency in Brachypodium distachyon and shrub willow (Salix spp.). Our results agree with those from previous studies of lignin mutants using enzymatic saccharification-based approaches. However, the use of C. phytofermentans takes into consideration specific organismal interactions, which will be crucial for simultaneous saccharification fermentation or consolidated bioprocessing. The ability to detect such phenotypic variation facilitates the genetic analysis of mechanisms underlying plant feedstock quality.

Biological conversion assay using Clostridium phytofermentans to estimate plant feedstock quality

PubMed Central

2012-01-01

Background There is currently considerable interest in developing renewable sources of energy. One strategy is the biological conversion of plant biomass to liquid transportation fuel. Several technical hurdles impinge upon the economic feasibility of this strategy, including the development of energy crops amenable to facile deconstruction. Reliable assays to characterize feedstock quality are needed to measure the effects of pre-treatment and processing and of the plant and microbial genetic diversity that influence bioconversion efficiency. Results We used the anaerobic bacterium Clostridium phytofermentans to develop a robust assay for biomass digestibility and conversion to biofuels. The assay utilizes the ability of the microbe to convert biomass directly into ethanol with little or no pre-treatment. Plant samples were added to an anaerobic minimal medium and inoculated with C. phytofermentans, incubated for 3 days, after which the culture supernatant was analyzed for ethanol concentration. The assay detected significant differences in the supernatant ethanol from wild-type sorghum compared with brown midrib sorghum mutants previously shown to be highly digestible. Compositional analysis of the biomass before and after inoculation suggested that differences in xylan metabolism were partly responsible for the differences in ethanol yields. Additionally, we characterized the natural genetic variation for conversion efficiency in Brachypodium distachyon and shrub willow (Salix spp.). Conclusion Our results agree with those from previous studies of lignin mutants using enzymatic saccharification-based approaches. However, the use of C. phytofermentans takes into consideration specific organismal interactions, which will be crucial for simultaneous saccharification fermentation or consolidated bioprocessing. The ability to detect such phenotypic variation facilitates the genetic analysis of mechanisms underlying plant feedstock quality. PMID:22316115

Anaerobic biodegradation of high-molecular-weight polycyclic aromatic hydrocarbons by a facultative anaerobe Pseudomonas sp. JP1.

PubMed

Liang, Lei; Song, Xiaohui; Kong, Jing; Shen, Chenghui; Huang, Tongwang; Hu, Zhong

2014-11-01

Polycyclic aromatic hydrocarbons (PAHs) are harmful persistent organic pollutants, while the high-molecular-weight (HMW) PAHs are even more detrimental to the environment and human health. However, microbial anaerobic degradation of HMW PAHs has rarely been reported. One facultative anaerobe Pseudomonas sp. JP1 was isolated from Shantou Bay, Shantou, China, which could degrade a variety of HMW PAHs. After 40 days cultivation with strain JP1, anaerobic biodegradation rate of benzo[a]pyrene (BaP), fluoranthene, and phenanthrene was 30, 47, and 5 %, respectively. Consumption of nitrate as the electron acceptor was confirmed by N-(1-naphthyl) ethylenediamine spectrophotometry. Supplementation of sodium sulfite, maltose, or glycine, and in a salinity of 0-20 ‰ significantly stimulated anaerobic degradation of BaP. Lastly, the anaerobic degradation metabolites of BaP by strain JP1 were investigated using GC/MS, and the degradation pathway was proposed. This study is helpful for further studies on the mechanism of anaerobic biodegradation of PAHs.

Conversion of Corn Stover Hydrolysates to Acids: Comparison Between Clostridium carboxidivorans P7 and Microbial Communities Developed from Lake Sediment and an Anaerobic Digester

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

Chen, Xiaowen; Tucker, Melvin P; Xia, Chunjie

Anaerobic fermentation is an environmentally sustainable technology for converting a variety of feedstocks to biofuels and bioproducts. Considering the complex nature of lignocellulosic hydrolysates, we aimed to investigate product formation from corn stover hydrolysates by using microbial communities under anaerobic conditions. A community developed from lake sediment was able to produce lactic acid from only glucose in the raw or overlimed hydrolysates. Another community from an anaerobic digester, however, was capable of using all hexose and pentose sugars in the raw and undetoxified hydrolysates and released lactic acid at 26.76 g/L. A pure acetogen, Clostridium carboxidivorans P7, was able tomore » grow on the raw and overlimed hydrolysates, too. But the consumption of sugars was minimal and the total released acid concentrations were less than 2 g/L. Next generation sequencing of the enriched community derived from the anaerobic digester revealed the presence of Lactobacillus strains. The predominant species were Lactobacillus parafarraginis (72.6%) and L. buchneri (13.4%). Product titer from using this enriched community can be further enhanced by cultivating at fed-batch or continuous fermentation modes. Results from this study widened the door for producing valuable products from lignocellulosic feedstocks through using mixed cultures.« less

Wingate Anaerobic Test Peak Power and Anaerobic Capacity Classification for Men and Women Intercollegiate Athletes

DTIC Science & Technology

2009-12-01

Dawson, LH, Wile , AL, Payn, TL, and Hannon, ME. Wingate Anaerobic Test peak power and anaerobic capacity classifications for men and women...139,2007. 6. Chromiah JA, Smedley, B, Carpenter, W, Brown , R, Koh, YS, Lamberth, JG, Joe, LA, Abadie, BR, and Altorfer, G. Effect of 10- week strength...Bnt J Sport Med 38: 784-789,2004. 8. Findley, BW, Brown , LE, and Whitehurst, M. Anaerobic power performance ofincumbent female firefrghters. J

Atmospheric vs. anaerobic processing of metabolome samples for the metabolite profiling of a strict anaerobic bacterium, Clostridium acetobutylicum.

PubMed

Lee, Sang-Hyun; Kim, Sooah; Kwon, Min-A; Jung, Young Hoon; Shin, Yong-An; Kim, Kyoung Heon

2014-12-01

Well-established metabolome sample preparation is a prerequisite for reliable metabolomic data. For metabolome sampling of a Gram-positive strict anaerobe, Clostridium acetobutylicum, fast filtration and metabolite extraction with acetonitrile/methanol/water (2:2:1, v/v) at -20°C under anaerobic conditions has been commonly used. This anaerobic metabolite processing method is laborious and time-consuming since it is conducted in an anaerobic chamber. Also, there have not been any systematic method evaluation and development of metabolome sample preparation for strict anaerobes and Gram-positive bacteria. In this study, metabolome sampling and extraction methods were rigorously evaluated and optimized for C. acetobutylicum by using gas chromatography/time-of-flight mass spectrometry-based metabolomics, in which a total of 116 metabolites were identified. When comparing the atmospheric (i.e., in air) and anaerobic (i.e., in an anaerobic chamber) processing of metabolome sample preparation, there was no significant difference in the quality and quantity of the metabolomic data. For metabolite extraction, pure methanol at -20°C was a better solvent than acetonitrile/methanol/water (2:2:1, v/v/v) at -20°C that is frequently used for C. acetobutylicum, and metabolite profiles were significantly different depending on extraction solvents. This is the first evaluation of metabolite sample preparation under aerobic processing conditions for an anaerobe. This method could be applied conveniently, efficiently, and reliably to metabolome analysis for strict anaerobes in air. © 2014 Wiley Periodicals, Inc.

Running-based Anaerobic Sprint Test as a Procedure to Evaluate Anaerobic Power.

PubMed

Andrade, V L; Zagatto, A M; Kalva-Filho, C A; Mendes, O C; Gobatto, C A; Campos, E Z; Papoti, M

2015-12-01

The aim of this study was to evaluate the use of the running anaerobic sprint test (RAST) as a predictor of anaerobic capacity, compare it to the maximal accumulated oxygen deficit (MAOD) and to compare the RAST's parameters with the parameters of 30-s all-out tethered running on a treadmill. 39 (17.0±1.4 years) soccer players participated in this study. The participants underwent an incremental test, 10 submaximal efforts [50-95% of velocity correspondent to VO(2MAX) (vVO(2MAX))] and one supramaximal effort at 110% of vVO(2MAX) for the determination of MAOD. Furthermore, the athletes performed the RAST. In the second stage the 30-s all-out tethered running was performed on a treadmill (30-s all-out), and compared with RAST. No significant correlation was observed between MAOD and RAST parameters. However, significant correlations were found between the power of the fifth effort (P5) of RAST with peak and mean power of 30-s all-out (r=0.73 and 0.50; p<0.05, respectively). In conclusion, the parameters from RAST do not have an association with MAOD, suggesting that this method should not be used to evaluate anaerobic capacity. Although the correlations between RAST parameters with 30-s all-out do reinforce the RAST as an evaluation method of anaerobic metabolism, such as anaerobic power. © Georg Thieme Verlag KG Stuttgart · New York.

Environmental impacts of anaerobic digestion and the use of anaerobic residues as soil amendment

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

Mosey, F.E.

1996-01-01

This paper defines the environmental role of anaerobic digestion within the overall objective of recovering energy from renewable biomass resources. Examples and opportunities for incorporating anaerobic digestion into biomass-to-energy schemes are discussed, together with environmental aspects of anaerobic digestion plants. These include visual, public amenity, pathogens and public health, odor control, and gaseous emissions. Digestate disposal and the benefits of restrictions on recycling organic wastes and biomass residues back to the land are discussed, particularly as they relate to American and European codes of practice and environmental legislation. The paper concludes that anaerobic digestion, if performed in purpose-designed reactors thatmore » efficiently recover and use biogas, is an environmentally benign process that can enhance energy recovery and aid the beneficial land use of plant residues in many biomass-to-energy schemes.« less

Reducing waste contamination from animal-processing plants by anaerobic thermophilic fermentation and by flesh fly digestion.

PubMed

Marchaim, U; Gelman, A; Braverman, Y

2003-01-01

There is currently no market in Israel for the large amounts of waste from fish- and poultry-processing plants. Therefore, this waste is incinerated, as part of the measures to prevent the spread of pathogens. Anaerobic methanogenic thermophilic fermentation (AMTF) of wastes from the cattle-slaughtering industry was examined previously, as an effective system to treat pathogenic bacteria, and in this article, we discuss a combined method of digestion by thermophilic anaerobic bacteria and by flesh flies, as a means of waste treatment. The AMTF process was applied to the wastes on a laboratory scale, and digestion by rearing of flesh fly (Phaenicia sericata) and housefly (Musca domestica) larvae on the untreated raw material was done on a small scale and showed remarkable weight conversion to larvae. The yield from degradation of poultry waste by flesh fly was 22.47% (SD = 3.89) and that from fish waste degradation was 35.34% (SD = 12.42), which is significantly higher than that from rearing houseflies on a regular rearing medium. Bacterial contents before and after thermophilic anaerobic digestion, as well as the changes in the chemical composition of the components during the rearing of larvae, were also examined.

Temperature regulates methane production through the function centralization of microbial community in anaerobic digestion.

PubMed

Lin, Qiang; De Vrieze, Jo; He, Guihua; Li, Xiangzhen; Li, Jiabao

2016-09-01

Temperature is crucial for the performance of anaerobic digestion process. In this study of anaerobic digestion of swine manure, the relationship between the microbial gene expression and methane production at different temperatures (25-55°C) was revealed through metatranscriptomic analysis. Daily methane production and total biogas production increased with temperature up to 50°C, but decreased at 55°C. The functional gene expression showed great variation at different temperatures. The function centralization (opposite to alpha-diversity), assessed by the least proportions of functional pathways contributing for at least 50% of total reads positively correlated to methane production. Temperature regulated methane production probably through reducing the diversity of functional pathways, but enhancing central functional pathways, so that most of cellular activities and resource were invested in methanogenesis and related pathways, enhancing the efficiency of conversion of substrates to methane. This research demonstrated the importance of function centralization for efficient system functioning. Copyright © 2016 Elsevier Ltd. All rights reserved.

Inhibition of Anaerobic Biological Treatment: A Review

NASA Astrophysics Data System (ADS)

Hou, Li; Ji, Dandan; Zang, Lihua

2018-01-01

Anaerobic digestion is a method for treating living and industrial wastewater by anaerobic degradation of organic compounds, which can produce biogas (carbon dioxide and methane mixture) and microbial biomass. And biogas as a renewable resource, can replace the use of ore fuel. In the process of anaerobic digestion, the problems of low methane yield and unstable reaction process are often encountered, which limits the widespread use of this technology. Various inhibitors are the main limiting factors for anaerobic digestion. In this paper, the main factors limiting anaerobic digestion are reviewed, and the latest research progress is introduced.

Can anaerobes be acid fast? A novel, clinically relevant acid fast anaerobe.

PubMed

Navas, Maria E; Jump, Robin; Canaday, David H; Wnek, Maria D; SenGupta, Dhruba J; McQuiston, John R; Bell, Melissa

2016-08-01

Anaerobic acid fast bacilli (AFB) have not been previously reported in clinical microbiology. This is the second case report of a novel anaerobic AFB causing disease in humans. An anaerobic AFB was isolated from an abdominal wall abscess in a 64-year-old Caucasian diabetic male, who underwent distal pancreatectomy and splenectomy for resection of a pancreatic neuroendocrine tumour. The isolated bacteria were gram-variable and acid-fast, consisting of small irregular rods. The 16S rRNA gene sequence analysis showed that the isolate is a novel organism described in the literature only once before. The organism was studied at the CDC (Centers for Disease Control and Prevention) by the same group that worked with the isolates from the previous report; their findings suggest that the strain belongs to the suborder Corynebacterineae. This is the fifth reported case of an anaerobic AFB involved in clinical disease; its microbiological features and 16S RNA sequence are identical to previously reported cases. Clinical disease with this organism seems to be associated with recent history of surgery and abscess formation in deep soft tissues. Acquisition from surgical material is uncertain but seems unlikely.

Implementation and process analysis of pilot scale multi-phase anaerobic fermentation and digestion of faecal sludge in Ghana

PubMed Central

Shih, Justin; Fanyin-Martin, Ato; Taher, Edris; Chandran, Kartik

2017-01-01

Background.  In Ghana, faecal sludge (FS) from on-site sanitation facilities is often discharged untreated into the environment, leading to significant insults to environmental and human health. Anaerobic digestion offers an attractive pathway for FS treatment with the concomitant production of energy in the form of methane. Another innovative option includes separating digestion into acidogenesis (production of volatile fatty acids (VFA)) and methanogenesis (production of methane), which could ultimately facilitate the production of an array of biofuels and biochemicals from the VFA. This work describes the development, implementation and modeling based analysis of a novel multiphase anaerobic fermentation-digestion process aimed at FS treatment in Kumasi, Ghana.  Methods.  A pilot-scale anaerobic fermentation process was implemented at the Kumasi Metropolitan Assembly’s Oti Sanitary Landfill Site at Adanse Dompoase.  The process consisted of six 10 m reactors in series, which were inoculated with bovine rumen and fed with fecal sludge obtained from public toilets.  The performance of the fermentation process was characterized in terms of both aqueous and gaseous variables representing the conversion of influent organic carbon to VFA as well as CH 4.  Using the operating data, the first-ever process model for FS fermentation and digestion was developed and calibrated, based on the activated sludge model framework. Results and Conclusions.  This work represents one of the first systematic efforts at integrated FS characterization and process modeling to enable anaerobic fermentation and digestion of FS. It is shown that owing to pre-fermentation of FS in public septage holding tanks, one could employ significantly smaller digesters (lower capital costs) or increased loading capabilities for FS conversion to biogas or VFA. Further, using the first-ever calibrated process model for FS fermentation and digestion presented herein, we expect improved and more

Implementation and process analysis of pilot scale multi-phase anaerobic fermentation and digestion of faecal sludge in Ghana.

PubMed

Shih, Justin; Fanyin-Martin, Ato; Taher, Edris; Chandran, Kartik

2017-11-06

Background.  In Ghana, faecal sludge (FS) from on-site sanitation facilities is often discharged untreated into the environment, leading to significant insults to environmental and human health. Anaerobic digestion offers an attractive pathway for FS treatment with the concomitant production of energy in the form of methane. Another innovative option includes separating digestion into acidogenesis (production of volatile fatty acids (VFA)) and methanogenesis (production of methane), which could ultimately facilitate the production of an array of biofuels and biochemicals from the VFA. This work describes the development, implementation and modeling based analysis of a novel multiphase anaerobic fermentation-digestion process aimed at FS treatment in Kumasi, Ghana.  Methods.  A pilot-scale anaerobic fermentation process was implemented at the Kumasi Metropolitan Assembly's Oti Sanitary Landfill Site at Adanse Dompoase.  The process consisted of six 10 m reactors in series, which were inoculated with bovine rumen and fed with fecal sludge obtained from public toilets.  The performance of the fermentation process was characterized in terms of both aqueous and gaseous variables representing the conversion of influent organic carbon to VFA as well as CH 4 .  Using the operating data, the first-ever process model for FS fermentation and digestion was developed and calibrated, based on the activated sludge model framework. Results and Conclusions.  This work represents one of the first systematic efforts at integrated FS characterization and process modeling to enable anaerobic fermentation and digestion of FS. It is shown that owing to pre-fermentation of FS in public septage holding tanks, one could employ significantly smaller digesters (lower capital costs) or increased loading capabilities for FS conversion to biogas or VFA. Further, using the first-ever calibrated process model for FS fermentation and digestion presented herein, we expect improved and more

Benzo[a]pyrene co-metabolism in the presence of plant root extracts and exudates: Implications for phytoremediation.

PubMed

Rentz, Jeremy A; Alvarez, Pedro J J; Schnoor, Jerald L

2005-08-01

Benzo[a]pyrene, a high molecular weight (HMW) polycyclic aromatic hydrocarbon (PAH) was removed from solution by Sphingomonas yanoikuyae JAR02 while growing on root products as a primary carbon and energy source. Plant root extracts of osage orange (Maclura pomifera), hybrid willow (Salix albaxmatsudana), or kou (Cordia subcordata), or plant root exudates of white mulberry (Morus alba) supported 15-20% benzo[a]pyrene removal over 24 h that was similar to a succinate grown culture and an unfed acetonitrile control. No differences were observed between the different root products tested. Mineralization of (14)C-7-benzo[a]pyrene by S. yanoikuyae JAR02 yielded 0.2 to 0.3% (14)CO(2) when grown with plant root products. Collectively, these observations were consistent with field observations of enhanced phytoremediation of HMW PAH and corroborated the hypothesis that co-metabolism may be a plant/microbe interaction important to rhizoremediation. However, degradation and mineralization was much less for root product-exposed cultures than salicylate-induced cultures, and suggested the rhizosphere may not be an optimal environment for HMW PAH degradation by Sphingomonas yanoikuyae JAR02.

Anaerobic biodegradability and treatment of grey water in upflow anaerobic sludge blanket (UASB) reactor.

PubMed

Elmitwalli, Tarek A; Otterpohl, Ralf

2007-03-01

Feasibility of grey water treatment in an upflow anaerobic sludge blanket (UASB) reactor operated at different hydraulic retention time (HRT) of 16, 10 and 6h and controlled temperature of 30 degrees C was investigated. Moreover, the maximum anaerobic biodegradability without inoculum addition and maximum removal of chemical oxygen demand (COD) fractions in grey water were determined in batch experiments. High values of maximum anaerobic biodegradability (76%) and maximum COD removal in the UASB reactor (84%) were achieved. The results showed that the colloidal COD had the highest maximum anaerobic biodegradability (86%) and the suspended and dissolved COD had similar maximum anaerobic biodegradability of 70%. Furthermore, the results of the UASB reactor demonstrated that a total COD removal of 52-64% was obtained at HRT between 6 and 16 h. The UASB reactor removed 22-30% and 15-21% of total nitrogen and total phosphorous in the grey water, respectively, mainly due to the removal of particulate nutrients. The characteristics of the sludge in the UASB reactor confirmed that the reactor had a stable performance. The minimum sludge residence time and the maximum specific methanogenic activity of the sludge ranged between 27 and 93 days and 0.18 and 0.28 kg COD/(kg VS d).

Enzymes and microorganisms in food industry waste processing and conversion to useful products: a review of the literature

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

Carroad, P.A.; Wilke, C.R.

1976-12-01

Bioconversion of food processing wastes is receiving increased attention with the realization that waste components represent an available and utilizable resource for conversion to useful products. Liquid wastes are characterized as dilute streams containing sugars, starches, proteins, and fats. Solid wastes are generally cellulosic, but may contain other biopolymers. The greatest potential for economic bioconversion is represented by processes to convert cellulose to glucose, glucose to alcohol and protein, starch to invert sugar, and dilute waste streams to methane by anaerobic digestion. Microbial or enzymatic processes to accomplish these conversions are described.

DNA-SIP based genome-centric metagenomics identifies key long-chain fatty acid-degrading populations in anaerobic digesters with different feeding frequencies

PubMed Central

Ziels, Ryan M; Sousa, Diana Z; Stensel, H David; Beck, David A C

2018-01-01

Fats, oils and greases (FOG) are energy-dense wastes that can be added to anaerobic digesters to substantially increase biomethane recovery via their conversion through long-chain fatty acids (LCFAs). However, a better understanding of the ecophysiology of syntrophic LCFA-degrading microbial communities in anaerobic digesters is needed to develop operating strategies that mitigate inhibitory LCFA accumulation from FOG. In this research, DNA stable isotope probing (SIP) was coupled with metagenomic sequencing for a genome-centric comparison of oleate (C18:1)-degrading populations in two anaerobic codigesters operated with either a pulse feeding or continuous-feeding strategy. The pulse-fed codigester microcosms converted oleate into methane at over 20% higher rates than the continuous-fed codigester microcosms. Differential coverage binning was demonstrated for the first time to recover population genome bins (GBs) from DNA-SIP metagenomes. About 70% of the 13C-enriched GBs were taxonomically assigned to the Syntrophomonas genus, thus substantiating the importance of Syntrophomonas species to LCFA degradation in anaerobic digesters. Phylogenetic comparisons of 13C-enriched GBs showed that phylogenetically distinct Syntrophomonas GBs were unique to each codigester. Overall, these results suggest that syntrophic populations in anaerobic digesters can have different adaptive capacities, and that selection for divergent populations may be achieved by adjusting reactor operating conditions to maximize biomethane recovery. PMID:28895946

Microbial conversion of choline to trimethylamine requires a glycyl radical enzyme

PubMed Central

Craciun, Smaranda; Balskus, Emily P.

2012-01-01

Choline and trimethylamine (TMA) are small molecules that play central roles in biological processes throughout all kingdoms of life. These ubiquitous metabolites are linked through a single biochemical transformation, the conversion of choline to TMA by anaerobic microorganisms. This metabolic activity, which contributes to methanogenesis and human disease, has been known for over a century but has eluded genetic and biochemical characterization. We have identified a gene cluster responsible for anaerobic choline degradation within the genome of a sulfate-reducing bacterium and verified its function using both a genetic knockout strategy and heterologous expression in Escherichia coli. Bioinformatics and electron paramagnetic resonance (EPR) spectroscopy revealed the involvement of a C–N bond cleaving glycyl radical enzyme in TMA production, which is unprecedented chemistry for this enzyme family. Our discovery provides the predictive capabilities needed to identify choline utilization clusters in numerous bacterial genomes, underscoring the importance and prevalence of this metabolic activity within the human microbiota and the environment. PMID:23151509

Anaerobic microplate assay for direct microbial conversion of switchgrass and Avicel using Clostridium thermocellum.

PubMed

Oguntimein, Gbekeloluwa B; Rodriguez, Miguel; Dumitrache, Alexandru; Shollenberger, Todd; Decker, Stephen R; Davison, Brian H; Brown, Steven D

2018-02-01

To develop and prototype a high-throughput microplate assay to assess anaerobic microorganisms and lignocellulosic biomasses in a rapid, cost-effective screen for consolidated bioprocessing potential. Clostridium thermocellum parent Δhpt strain deconstructed Avicel to cellobiose, glucose, and generated lactic acid, formic acid, acetic acid and ethanol as fermentation products in titers and ratios similar to larger scale fermentations confirming the suitability of a plate-based method for C. thermocellum growth studies. C. thermocellum strain LL1210, with gene deletions in the key central metabolic pathways, produced higher ethanol titers in the Consolidated Bioprocessing (CBP) plate assay for both Avicel and switchgrass fermentations when compared to the Δhpt strain. A prototype microplate assay system is developed that will facilitate high-throughput bioprospecting for new lignocellulosic biomass types, genetic variants and new microbial strains for bioethanol production.

Anaerobic microplate assay for direct microbial conversion of switchgrass and Avicel using Clostridium thermocellum

DOE PAGES

Oguntimein, Gbekeloluwa B.; Rodriguez, Jr., Miguel; Dumitrache, Alexandru; ...

2017-11-09

Here, to develop and prototype a high-throughput microplate assay to assess anaerobic microorganisms and lignocellulosic biomasses in a rapid, cost-effective screen for consolidated bioprocessing potential. Clostridium thermocellum parent Δ hpt strain deconstructed Avicel to cellobiose, glucose, and generated lactic acid, formic acid, acetic acid and ethanol as fermentation products in titers and ratios similar to larger scale fermentations confirming the suitability of a plate-based method for C. thermocellum growth studies. C. thermocellum strain LL1210, with gene deletions in the key central metabolic pathways, produced higher ethanol titers in the Consolidated Bioprocessing (CBP) plate assay for both Avicel and switchgrass fermentationsmore » when compared to the Δ hpt strain. A prototype microplate assay system is developed that will facilitate high-throughput bioprospecting for new lignocellulosic biomass types, genetic variants and new microbial strains for bioethanol production.« less

Anaerobic microplate assay for direct microbial conversion of switchgrass and Avicel using Clostridium thermocellum

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

Oguntimein, Gbekeloluwa B.; Rodriguez, Jr., Miguel; Dumitrache, Alexandru

Here, to develop and prototype a high-throughput microplate assay to assess anaerobic microorganisms and lignocellulosic biomasses in a rapid, cost-effective screen for consolidated bioprocessing potential. Clostridium thermocellum parent Δ hpt strain deconstructed Avicel to cellobiose, glucose, and generated lactic acid, formic acid, acetic acid and ethanol as fermentation products in titers and ratios similar to larger scale fermentations confirming the suitability of a plate-based method for C. thermocellum growth studies. C. thermocellum strain LL1210, with gene deletions in the key central metabolic pathways, produced higher ethanol titers in the Consolidated Bioprocessing (CBP) plate assay for both Avicel and switchgrass fermentationsmore » when compared to the Δ hpt strain. A prototype microplate assay system is developed that will facilitate high-throughput bioprospecting for new lignocellulosic biomass types, genetic variants and new microbial strains for bioethanol production.« less

Performance and microbial community analysis of the anaerobic reactor with coke oven gas biomethanation and in situ biogas upgrading.

PubMed

Wang, Wen; Xie, Li; Luo, Gang; Zhou, Qi; Angelidaki, Irini

2013-10-01

A new method for simultaneous coke oven gas (COG) biomethanation and in situ biogas upgrading in anaerobic reactor was developed in this study. The simulated coke oven gas (SCOG) (92% H2 and 8% CO) was injected directly into the anaerobic reactor treating sewage sludge through hollow fiber membrane (HFM). With pH control at 8.0, the added H2 and CO were fully consumed and no negative effects on the anaerobic degradation of sewage sludge were observed. The maximum CH4 content in the biogas was 99%. The addition of SCOG resulted in enrichment and dominance of homoacetogenetic genus Treponema and hydrogenotrophic genus Methanoculleus in the liquid, which indicated that H2 were converted to methane by both direct (hydrogenotrophic methanogenesis) and indirect (homoacetogenesis+aceticlastic methanogenesis) pathways in the liquid. However, the aceticlasitic genus Methanosaeta was dominant for archaea in the biofilm on the HFM, which indicated indirect (homoacetogenesis+aceticlastic methanogenesis) H2 conversion pathway on the biofilm. Copyright © 2013 Elsevier Ltd. All rights reserved.

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

Incidence and significance of intraperitoneal anaerobic bacteria.

PubMed Central

Stone, H H; Kolb, L D; Geheber, C E

1975-01-01

To amplify recent interest in anaerobic infections following abdominal disease, trauma, or surgery, 512 consecutive patients subjected to emergency celiotomy had both aerobic and anaerobic cultures taken of peritoneal fluid as well as all complicating wound and intra-abdominal infections. Average time between peritoneal entry of abscess drainage and specimen incubating under anaerobic conditions was less than two minutes. During 4 of the seven study months, patients had antibiotic therapy randomized, with clindaymcin or cephalothin being sole parenteral agents and given intravenously prior to operation and for 5 days thereafter. Results demonstrated that anaerobes uniformly contaminate the peritoneal cavity whenever distal or obstructed intestine has been perforated, irrespective of the cause. Although all but one of the 123 complicating wound and intra-abdominal infections were due solely or at least in part to aerobic pathogens, 2/3 of such infections also contained one or more different anaerobic species acting in synergism with the aerobes. No significant difference in incidence of postoperative infection or in infecting bacteria could be found with respect to antibiotic administered or etiology of perforation. Indeed, duration of bacterial exposure to atmospheric oxygen was the most critical factor influencing culture recoverability of anaerobic organisms, likelihood of ensuing wound or peritoneal sepsis participated in by an anaerobe, and success in control of established infections harboring anaerobes. PMID:1130885

In Situ Bioremediation of 1,4-Dioxane by Methane Oxidizing Bacteria in Coupled Anaerobic-Aerobic Zones

DTIC Science & Technology

2016-02-11

groundwater in situ. Because of its low Koc and Henry’s Law constant, traditional remediation technologies such as carbon adsorption and air stripping...of 1,4-dioxane via methane oxidizing bacteria is of particular interest for in situ remedial purposes for two reasons. (1) Cometabolic mechanisms...2010. Final Remedial Action Report: Building 165 and Area 18C Groundwater Treatment Pilot Systems; Former Raritan Arsenal Project, Edison, NJ. US

Toward Narrowing Fermentation Endproduct Distribution in Undefined Mixed Culture Anaerobic Conversion of Lignocellulosic Corn Fiber to Butyrate

USDA-ARS?s Scientific Manuscript database

Conversion of second-generation renewable energy sources to useful products is gaining attention as an alternative to traditional conversion of sugar and starch-based renewable energy crops. The natural recalcitrance of second-generation energy resources, such as (ligno)cellulosic feedstock, makes ...

Isolation of anaerobes from bubo associated with chancroid.

PubMed Central

Kumar, B; Sharma, V K; Bakaya, V; Ayyagiri, A

1991-01-01

Ten men with bubo associated with chancroid were studied for bacterial flora especially anaerobes. Anaerobes were isolated from all 10 buboes and eight out of 10 ulcers of chancroid. Anaerobic cocci, B melaninogenicus and B fragilis were the most common isolates. anaerobes probably play a role in the pathogenesis of bubo in chancroid. PMID:1680792

Anaerobic bacteraemia revisited: species and susceptibilities.

PubMed

Ng, Lily S Y; Kwang, Lee Ling; Rao, Suma; Tan, Thean Yen

2015-01-01

This retrospective study was performed to evaluate the frequency of anaerobic bacteraemia over a 10-year period, and to provide updated antibiotic susceptibilities for the more clinically relevant anaerobes causing blood stream infection. Data were retrieved from the laboratory information system for the period 2003 to 2012. During this time, blood cultures were inoculated in Bactec™ Plus vials (BD, USA) and continuously monitored in the Bactec™ 9000 blood culture system (BD, USA). Anaerobic organisms were identified using commercial identification kits, predominantly API 20 A (bioMérieux, France) supplemented with Vitek ANC cards (bioMérieux, France) and AN-Ident discs (Oxoid, United Kingdom). A representative subset of isolates were retrieved from 2009 to 2011 and antimicrobial susceptibilities to penicillin, amoxicillin-clavulanate, clindamycin, imipenem, moxifloxacin, piperacillin-tazobactam and metronidazole were determined using the Etest method. Anaerobes comprised 4.1% of all positive blood culture with 727 obligate anaerobes recovered over the 10-year period, representing a positivity rate of 0.35%. The only significant change in anaerobe positivity rates occurred between 2003 and 2004, with an increase of 0.2%. The Bacteroides fragilis group (45%) were the predominant anaerobic pathogens, followed by Clostridium species (12%), Propioniobacterium species (11%) and Fusobacterium species (6%). The most active in vitro antibiotics were imipenem, piperacillin-tazobactam, amoxicillin-clavulanate and metronidazole, with susceptibilities of 95.0%, 93.3%, 90.8% and 90.8% respectively. Resistance was high to penicillin, clindamycin and moxifl oxacin. However, there were apparent differences for antibiotic susceptibilities between species. This study indicates that the anaerobes comprise a small but constant proportion of bloodstream isolates. Antibiotic resistance was high to some antibiotics, but metronidazole, the beta-lactam/beta-lactamase inhibitors and

Anaerobic biodegradation of aromatic compounds.

PubMed

Jothimani, P; Kalaichelvan, G; Bhaskaran, A; Selvaseelan, D Augustine; Ramasamy, K

2003-09-01

Many aromatic compounds and their monomers are existing in nature. Besides they are introduced into the environment by human activity. The conversion of these aromatic compounds is mainly an aerobic process because of the involvement of molecular oxygen in ring fission and as an electron acceptor. Recent literatures indicated that ring fission of monomers and obligomers mainly occurs in anaerobic environments through anaerobic respiration with nitrate, sulphate, carbon dioxide or carbonate as electron acceptors. These anaerobic processes will help to work out the better situation for bioremediation of contaminated environments. While there are plenty of efforts to reduce the release of these chemicals to the environment, already contaminated sites need to be remediated not only to restore the sites but to prevent the leachates spreading to nearby environment. Basically microorganisms are better candidates for breakdown of these compounds because of their wider catalytic mechanisms and the ability to act even in the absence of oxygen. These microbes can be grouped based on their energy mechanisms. Normally, the aerobic counterparts employ the enzymes like mono-and-dioxygenases. The end product is basically catechol, which further may be metabolised to CO2 by means of quinones reductases cycles. In the absense of reductases compounds, the reduced catechols tend to become oxidised to form many quinone compounds. The quinone products are more recalcitrant and lead to other aesthetic problems like colour in water, unpleasant odour, etc. On the contrary, in the reducing environment this process is prevented and in a cascade of pathways, the cleaved products are converted to acetyl co-A to be integrated into other central metabolite paths. The central metabolite of anaerobic degradation is invariably co-A thio-esters of benzoic acid or hydroxy benzoic acid. The benzene ring undergoes various substitution and addition reactions to form chloro-, nitro-, methyl- compounds

Electrooxidation as the anaerobic pre-treatment of fats: oleate conversion using RuO2 and IrO2 based anodes.

PubMed

Gonçalves, M; Alves, M M; Correia, J P; Marques, I P

2008-11-01

Electrochemical treatment of oleate using RuO2 and IrO2 type dimensionally stable anodes in alkaline medium was performed to develop a feasible anaerobic pre-treatment of fatty effluents. The results showed that the pre-treated solutions over RuO2 were faster degraded by anaerobic consortium than the raw oleate solutions or the electrolysed solutions using IrO2. In batch experiments carried out with pre-treated solutions over RuO2 (100-500mg/L), no lag phases were observed before the methane production onset. On the other hand, raw oleate and pre-treated oleate over IrO2 had originated lag phases of 0-140 and 0-210h, respectively. This study demonstrated that it is advantageous to apply the electrochemical treatment carried out on the RuO2 type DSA in order to achieve a faster biodegradation of lipid-containing effluent and consequently to obtain a faster methane production.

The anaerobic digestion process

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

Rivard, C.J.; Boone, D.R.

1996-01-01

The microbial process of converting organic matter into methane and carbon dioxide is so complex that anaerobic digesters have long been treated as {open_quotes}black boxes.{close_quotes} Research into this process during the past few decades has gradually unraveled this complexity, but many questions remain. The major biochemical reactions for forming methane by methanogens are largely understood, and evolutionary studies indicate that these microbes are as different from bacteria as they are from plants and animals. In anaerobic digesters, methanogens are at the terminus of a metabolic web, in which the reactions of myriads of other microbes produce a very limited rangemore » of compounds - mainly acetate, hydrogen, and formate - on which the methanogens grow and from which they form methane. {open_quotes}Interspecies hydrogen-transfer{close_quotes} and {open_quotes}interspecies formate-transfer{close_quotes} are major mechanisms by which methanogens obtain their substrates and by which volatile fatty acids are degraded. Present understanding of these reactions and other complex interactions among the bacteria involved in anaerobic digestion is only now to the point where anaerobic digesters need no longer be treated as black boxes.« less

Diversity Profile of Microbes Associated with Anaerobic Sulfur Oxidation in an Upflow Anaerobic Sludge Blanket Reactor Treating Municipal Sewage

PubMed Central

Aida, Azrina A.; Kuroda, Kyohei; Yamamoto, Masamitsu; Nakamura, Akinobu; Hatamoto, Masashi; Yamaguchi, Takashi

2015-01-01

We herein analyzed the diversity of microbes involved in anaerobic sulfur oxidation in an upflow anaerobic sludge blanket (UASB) reactor used for treating municipal sewage under low-temperature conditions. Anaerobic sulfur oxidation occurred in the absence of oxygen, with nitrite and nitrate as electron acceptors; however, reactor performance parameters demonstrated that anaerobic conditions were maintained. In order to gain insights into the underlying basis of anaerobic sulfur oxidation, the microbial diversity that exists in the UASB sludge was analyzed comprehensively to determine their identities and contribution to sulfur oxidation. Sludge samples were collected from the UASB reactor over a period of 2 years and used for bacterial 16S rRNA gene-based terminal restriction fragment length polymorphism (T-RFLP) and next-generation sequencing analyses. T-RFLP and sequencing results both showed that microbial community patterns changed markedly from day 537 onwards. Bacteria belonging to the genus Desulforhabdus within the phylum Proteobacteria and uncultured bacteria within the phylum Fusobacteria were the main groups observed during the period of anaerobic sulfur oxidation. Their abundance correlated with temperature, suggesting that these bacterial groups played roles in anaerobic sulfur oxidation in UASB reactors. PMID:25817585

Genome-centric metatranscriptomes and ecological roles of the active microbial populations during cellulosic biomass anaerobic digestion.

PubMed

Jia, Yangyang; Ng, Siu-Kin; Lu, Hongyuan; Cai, Mingwei; Lee, Patrick K H

2018-01-01

microbial conversion of lignocellulosic biomass to methane. The knowledge of this study can facilitate development of potential biomarkers and rational design of the microbiome in anaerobic digesters.

Modified anaerobic digestion elutriated phased treatment for the anaerobic co-digestion of sewage sludge and food wastewater.

PubMed

Mo, Kyung; Lee, Wonbae; Kim, Moonil

2017-02-01

A modified anaerobic digestion elutriated phased treatment (MADEPT) process was developed for investigating anaerobic co-digestion of sewage sludge and food wastewater. The anaerobic digestion elutriated phased treatment (ADEPT) process is similar to a two-phase system, however, in which the effluent from a methanogenic reactor recycles into an acidogenic reactor to elutriate mainly dissolved organics. Although ADEPT could reduce reactor volume significantly, the unsolubilized solids should be wasted from the system. The MADEPT process combines thermo-alkali solubilization with ADEPT to improve anaerobic performance and to minimize the sludge disposal. It was determined that the optimal volume mixing ratio of sewage sludge and food wastewater was 4 : 1 for the anaerobic co-digestion. The removal efficiencies of total chemical oxygen demand, volatile solids, and volatile suspended solids in the MADEPT process were 73%, 70%, and 64%, respectively. However, those in the ADEPT process were only 48%, 37%, and 40%, respectively, at the same hydraulic retention time (HRT) of 7 days. The gas production of MADEPT was two times higher than that of ADEPT. The thermo-alkali solubilization increased the concentration of dissolved organics so that they could be effectively degraded in a short HRT, implying that MADEPT could improve the performance of ADEPT in anaerobic co-digestion.

Anaerobic infections in surgical wards: a two year study

PubMed Central

Ananth-Shenoy, Padmaja; Vishwanath, Shashidhar; Targain, Ryumzook; Shetty, Seema; Sunil-Rodrigues, Gabriel; Mukhopadhyay, Chiranjay; Chawla, Kiran

2016-01-01

Background and Objectives: Anaerobic bacteria are recognized as important pathogens in surgical infections. However, they are the most overlooked microorganisms by the clinic and the laboratory because of the tedious culture techniques with longer turn-around times. The study was aimed to analyze the frequency of anaerobic bacterial surgical infections and their predisposing factors. Materials and Methods: A retrospective study was conducted over a period of two years including patients with surgical infections. The specimens were processed by Gram staining, aerobic and anaerobic culture. The anaerobic bacteria were isolated using standard procedures. The predisposing factors and clinical presentation were studied in these patients. Results: A total of 261 specimens were received from patients with diverse infections from surgical wards. Ninety-one anaerobes were isolated from 64 (24.5%) surgical patients with a predominance of Gram-negative bacilli (37.4%). Anaerobic bacteria as monomicrobial isolates were seen in 21.9% isolates. Anaerobic bacterial isolation along with aerobic bacteria was seen in 71.9% of patients and polymicrobial anaerobic growth was detected in 6.3% of patients. Diabetes mellitus (28, 43.8%) was found to be the most frequent predisposing factor. Bacteroides fragilis group (20.9%) were the most frequent anaerobic Gram-negative bacilli followed by Prevotella spp. (12.1%). Peptostreptococcus anaerobius was the predominant anaerobic cocci isolated (14.3%). Necrotizing fascitis (34.4%) was the most common clinical presentation with anaerobic etiology followed by deep seated abscesses (23.4%). Conclusion: Anaerobic bacteria were isolated from a significant proportion of surgical infections. To avoid therapeutic failures, anaerobic bacteria in surgical infections need to be recognized by surgeons and laboratorians. PMID:27928485

Antibiotic Production by Anaerobic Bacteria1

PubMed Central

Sturgen, Nancy O.; Casida, L. E.

1962-01-01

Soils from aerobic and anaerobic sources were investigated for the possible presence of bacteria which produce antibiotics under anaerobic conditions of growth. The screening techniques devised for this study yielded 157 soil bacteria which, during anaerobic growth, produced antibiotic activity against aerobic test bacteria. Studies on choice of media, presence of oxygen, and changes in antibiotic activity during growth indicated that representative strains of these bacteria produced mixtures of antibiotics. The activity was heat labile. PMID:13918037

Single-cell genomics reveals co-metabolic interactions within uncultivated Marine Group A bacteria

NASA Astrophysics Data System (ADS)

Hawley, A. K.; Hallam, S. J.

2016-02-01

Marine Group A (MGA) bacteria represent a ubiquitous and abundant candidate phylum enriched in oxygen minimum zones (OMZs) and the deep ocean. Despite MGA prevalence little is known about their ecology and biogeochemistry. Here we chart the metabolic potential of 26 MGA single-cell amplified genomes sourced from different environments spanning ecothermodynamic gradients including open ocean waters, OMZs and methanogenic environments including a terephthalate-degrading bioreactor. Metagenomic contig recruitment to SAGs combined with tetra-nucleotide frequency distribution patterns resolved nine MGA population genome bins. All population genomes exhibited genomic streamlining with open ocean MGA being the most reduced. Different strategies for carbohydrate utilization, carbon fixation energy metabolism and respiratory pathways were identified between population genome bins, including various roles in the nitrogen and sulfur cycles. MGA inhabiting OMZ oxyclines encoded genes for partial denitrification with potential to feed into anammox and nitrification as well as a polysulfide reductase with a potential role in the cryptic sulfur cycle. MGA inhabiting anoxic waters, encoded NiFe hydrogenase and nitrous oxide reductase with the potential to complete partial denitrification pathways previously linked to sulfur oxidation in SUP05 bacteria. MGA from methanogenic environments encoded genes mediating cascading syntrophic interactions with fatty acid degraders and methanogens including reverse electron transport potential. The MGA phylum appears to have evolved alternative metabolic innovations adapting specific subgroups to occupy specific niches along ecothermodynamic gradients. Additionally, expression of MGA genes from different OMZ environments supports that these subgroups manifest an increasing propensity for co-metabolic interactions under energy limiting conditions that mandates a cooperative mode of existence with important implications for C, N and S cycling in

Application of rumen microorganisms for anaerobic bioconversion of lignocellulosic biomass.

PubMed

Yue, Zheng-Bo; Li, Wen-Wei; Yu, Han-Qing

2013-01-01

Rumen in the mammalian animals is a natural cellulose-degrading system and the microorganisms inside have been found to be able to effectively digest lignocellulosic biomass. Furthermore, methane or volatile fatty acids, which could be further converted to other biofuels, are the two major products in such a system. This paper offers an overview of recent development in the application of rumen microorganisms for lignocellulosic biomass conversion. Application of recent molecular tools in the analysis of rumen microbial community, progress in the development of artificial rumen reactors, the latest research results about characterizing rumen-dominated anaerobic digestion process and energy products are summarized. Also, the potential application of such a rumen-dominated process is discussed. Copyright © 2012 Elsevier Ltd. All rights reserved.

Anaerobic benzene degradation by bacteria

PubMed Central

Vogt, Carsten; Kleinsteuber, Sabine; Richnow, Hans‐Hermann

2011-01-01

Summary Benzene is a widespread and toxic contaminant. The fate of benzene in contaminated aquifers seems to be primarily controlled by the abundance of oxygen: benzene is aerobically degraded at high rates by ubiquitous microorganisms, and the oxygen‐dependent pathways for its breakdown were elucidated more than 50 years ago. In contrast, benzene was thought to be persistent under anoxic conditions until 25 years ago. Nevertheless, within the last 15 years, several benzene‐degrading cultures have been enriched under varying electron acceptor conditions in laboratories around the world, and organisms involved in anaerobic benzene degradation have been identified, indicating that anaerobic benzene degradation is a relevant environmental process. However, only a few benzene degraders have been isolated in pure culture so far, and they all use nitrate as an electron acceptor. In some highly enriched strictly anaerobic cultures, benzene has been described to be mineralized cooperatively by two or more different organisms. Despite great efforts, the biochemical mechanism by which the aromatic ring of benzene is activated in the absence of oxygen is still not fully elucidated; methylation, hydroxylation and carboxylation are discussed as likely reactions. This review summarizes the current knowledge about the ‘key players’ of anaerobic benzene degradation under different electron acceptor conditions and the possible pathway(s) of anaerobic benzene degradation. PMID:21450012

A new method of two-phase anaerobic digestion for fruit and vegetable waste treatment.

PubMed

Wu, Yuanyuan; Wang, Cuiping; Liu, Xiaoji; Ma, Hailing; Wu, Jing; Zuo, Jiane; Wang, Kaijun

2016-07-01

A novel method of two-phase anaerobic digestion where the acid reactor is operated at low pH 4.0 was proposed and investigated. A completely stirred tank acid reactor and an up-flow anaerobic sludge bed methane reactor were operated to examine the possibility of efficient degradation of lactate and to identify their optimal operating conditions. Lactate with an average concentration of 14.8g/L was the dominant fermentative product and Lactobacillus was the predominant microorganism in the acid reactor. The effluent from the acid reactor was efficiently degraded in the methane reactor and the average methane yield was 261.4ml/gCOD removed. Organisms of Methanosaeta were the predominant methanogen in granular sludge of methane reactor, however, after acclimation hydrogenotrophic methanogens enriched, which benefited for the conversion of lactate to acetate. The two-phase AD system exhibited a low hydraulic retention time of 3.56days and high methane yield of 348.5ml/g VS removed. Copyright © 2016 Elsevier Ltd. All rights reserved.

Increased Gut Redox and Depletion of Anaerobic and Methanogenic Prokaryotes in Severe Acute Malnutrition

PubMed Central

Million, Matthieu; Tidjani Alou, Maryam; Khelaifia, Saber; Bachar, Dipankar; Lagier, Jean-Christophe; Dione, Niokhor; Brah, Souleymane; Hugon, Perrine; Lombard, Vincent; Armougom, Fabrice; Fromonot, Julien; Robert, Catherine; Michelle, Caroline; Diallo, Aldiouma; Fabre, Alexandre; Guieu, Régis; Sokhna, Cheikh; Henrissat, Bernard; Parola, Philippe; Raoult, Didier

2016-01-01

Severe acute malnutrition (SAM) is associated with inadequate diet, low levels of plasma antioxidants and gut microbiota alterations. The link between gut redox and microbial alterations, however, remains unexplored. By sequencing the gut microbiomes of 79 children of varying nutritional status from three centers in Senegal and Niger, we found a dramatic depletion of obligate anaerobes in malnutrition. This was confirmed in an individual patient data meta-analysis including 107 cases and 77 controls from 5 different African and Asian countries. Specifically, several species of the Bacteroidaceae, Eubacteriaceae, Lachnospiraceae and Ruminococceae families were consistently depleted while Enterococcus faecalis, Escherichia coli and Staphylococcus aureus were consistently enriched. Further analyses on our samples revealed increased fecal redox potential, decreased total bacterial number and dramatic Methanobrevibacter smithii depletion. Indeed, M. smithii was detected in more than half of the controls but in none of the cases. No causality was demonstrated but, based on our results, we propose a unifying theory linking microbiota specificity, lacking anaerobes and archaea, to low antioxidant nutrients, and lower food conversion. PMID:27183876

Cavitation for improved sludge conversion into biogas

NASA Astrophysics Data System (ADS)

Stoop, A. H.; Bakker, T. W.; Kramer, H. J. M.

2015-12-01

In several studies the beneficial influence of pre-treatment of waste activated sludge with cavitation on the biogas production was demonstrated. It is however, still not fully certain whether this effect should be mainly contributed to an increase in conversion rate of organics into biogas by anaerobic bacteria, and how much cavitation increases the total biogas yield. An increase in yield is only the case if cavitation can further disrupt otherwise inaccessible cell membrane structures and long chain organic molecules. In this study the influence of hydrodynamic cavitation on sludge that was already digested for 30 days was investigated. The total biogas yield could indeed be increased. The effect of the backpressure behind the venturi tube on the yield could not yet be established.

Biodegradation of 5-chloro-2-picolinic acid by novel identified co-metabolizing degrader Achromobacter sp. f1.

PubMed

Wu, Zhi-Guo; Wang, Fang; Ning, Li-Qun; Stedtfeld, Robert D; Yang, Zong-Zheng; Cao, Jing-Guo; Sheng, Hong-Jie; Jiang, Xin

2017-06-01

Several bacteria have been isolated to degrade 4-chloronitrobenzene. Degradation of 4-chloronitrobenzene by Cupriavidus sp. D4 produces 5-chloro-2-picolinic acid as a dead-end by-product, a potential pollutant. To date, no bacterium that degrades 5-chloro-2-picolinic acid has been reported. Strain f1, isolated from a soil polluted by 4-chloronitrobenzene, was able to co-metabolize 5-chloro-2-picolinic acid in the presence of ethanol or other appropriate carbon sources. The strain was identified as Achromobacter sp. based on its physiological, biochemical characteristics, and 16S rRNA gene sequence analysis. The organism completely degraded 50, 100 and 200 mg L -1 of 5-chloro-2-picolinic acid within 48, 60, and 72 h, respectively. During the degradation of 5-chloro-2-picolinic acid, Cl - was released. The initial metabolic product of 5-chloro-2-picolinic acid was identified as 6-hydroxy-5-chloro-2-picolinic acid by LC-MS and NMR. Using a mixed culture of Achromobacter sp. f1 and Cupriavidus sp. D4 for degradation of 4-chloronitrobenzen, 5-chloro-2-picolinic acid did not accumulate. Results infer that Achromobacter sp. f1 can be used for complete biodegradation of 4-chloronitrobenzene in remedial applications.

Study on potency of municipal solid waste conversion into renewable energy by thermal incineration and bioconversion: case study of Medan city

NASA Astrophysics Data System (ADS)

Sarah, Maya; Misran, Erni

2018-03-01

Municipal solid waste (MSW) in Medan City is facing problems either with the quantity and management of MSW. Local authority only dumped approximately 73.9% MSW in the landfill over the years. Spontaneous phenomena of methane formation in dumping site indicates the potency of MSW conversion into energy by biochemical conversion. On the contrary, the presence of plastics, woods, papers, etc. in the MSW show the potency of MSW to be treated by thermal conversion. Both thermal incineration and anaerobic digestion may convert MSW Medan City into energy. This study evaluates potency of MSW conversion into renewable energy using proximate and ultimate analysis. Overall, MSW of Medan City has the opportunities to be converted into energy by both thermal and biochemical conversion with a special requirement such as pre-dry the MSW prior incineration process and degrade organic MSW in a bioreactor.

Anaerobic digestion for sustainable development: a natural approach.

PubMed

Gljzen, H J

2002-01-01

After the discovery of methane gas by Alessandro Volta in 1776, it took about 100 years before anaerobic processes for the treatment of wastewater and sludges were introduced. The development of high rate anaerobic digesters for the treatment of sewage and industrial wastewater took until the nineteen-seventies and for solid waste even till the nineteen-eighties. All digesters have in common that they apply natural anaerobic consortia of microorganisms for degradation and transformation processes. In view of this, it could be rewarding to evaluate the efficiency of natural ecosystems for their possible application. Examples of high rate anaerobic natural systems include the forestomach of ruminants and the hindgut of certain insects, such as termites and cockroaches. These 'natural reactors' exhibit volumetric methane production rates as high as 35 l/l.d. The development of anaerobic reactors based on such natural anaerobic systems could produce eco-technologies for the effective management of a wide variety of solid wastes and industrial wastewater. Important limitations of anaerobic treatment of domestic sewage relate to the absence of nutrient and pathogen removal. A combination of anaerobic pre-treatment followed by photosynthetic posttreatment is proposed for the effective recovery of energy and nutrients from sewage. This eco-technology approach is based on the recognition that the main nutrient assimilating capacity is housed in photosynthetic plants. The proposed anaerobic-photosynthetic process is energy efficient, cost effective and applicable under a wide variety of rural and urban conditions. a natural systems approach towards waste management could generate affordable eco-technologies for effective treatment and resource recovery.

Methane production by anaerobic digestion of Bermuda grass

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

Klass, D.L.; Ghosh, S.

1979-01-01

Bermuda grass (Cynodon dactylon) is one of the high-yield warm-season grasses that has been suggested as a promising raw material for conversion to methane. Experimental work performed with laboratory digesters to study the anaerobic digestion of Coastal Bermuda grass harvested in Louisiana and having a C/N ratio of 24 is described. Methane yields of about 1.9 SCF/lb of volatile solids( VS) added were observed under conventional mesophilic high-rate conditions. When supplemental nitrogen additions were made, the yields increased up to 3.5 SCF/lb of VS added indicating that the nitrogen content of the grass examined was insufficient to sustain high-rate digestionmore » at the higher yield level. Thermophilic digestion with supplemental nitrogen additions afforded methane yields of about 2.7 SCF/lb VS added. Carbon and energy balances were calculated and the relative biodegradabilities of the organics were estimated.« less

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

Riha, B.; Looney, B.; Noonkester, J.

cometabolism). For TArea, the enhanced attenuation development process proved to be a powerful tool in developing a strategy that provides a high degree of performance while minimizing adverse collateral impacts of the remediation (e.g., energy use and wetland damage) and minimizing life-cycle costs. As depicted in Figure 1, Edible oil deployment results in the development of structured geochemical zones and serves to decrease chlorinated compound concentrations in two ways: (1) physical sequestration, which reduces effective aqueous concentration and mobility; and (2) stimulation of anaerobic, abiotic and cometabolic degradation processes. In the central deployment area, contaminant initially partitions into the added oil phase. Biodegradation of the added organic substrate depletes the aquifer of oxygen and other terminal electron acceptors and creates conditions conducive to anaerobic degradation processes. The organic substrate is fermented to produce hydrogen, which is used as an electron donor for anaerobic dechlorination by organisms such as Dehalococcoides. Daughter products leaving the central treatment zone are amenable to aerobic oxidation. Further, the organic compounds leaving the central deployment zone (e.g., methane and propane) stimulate and enhance down gradient aerobic cometabolism which degrades both daughter compounds and several parent cVOCs. Figure 1 depicts TCE concentration reduction processes (labeled in green) along with their corresponding breakdown products in a structured geochemical zone scenario. A consortium of bacteria with the same net effect of Dehalococcoides may be present in the structured geochemical zones leading to the degradation of TCE and daughter products. Figure 2 shows a schematic of the documented cVOC degradation processes in both the anaerobic and aerobic structured geochemical zones. Specific aerobic and anaerobic bacteria and their degradation pathways are also listed in the diagram and have either been confirmed in the

Anaerobic digestion foaming causes--a review.

PubMed

Ganidi, Nafsika; Tyrrel, Sean; Cartmell, Elise

2009-12-01

Anaerobic digestion foaming has been encountered in several sewage treatment plants in the UK. Foaming has raised major concerns for the water companies due to significant impacts on process efficiency and operational costs. Several foaming causes have been identified over the past few years by researchers. However, the supporting experimental information is limited and in some cases absent. The present report aims to provide a detailed review of the current anaerobic digestion foaming problem and to identify gaps in knowledge regarding the theory of foam formation in anaerobic digesters.

Gardnerella vaginalis and anaerobic bacteria in genital disease.

PubMed Central

Tabaqchali, S; Wilks, M; Thin, R N

1983-01-01

In a study of Gardnerella vaginalis and anaerobic bacteria in non-specific vaginitis (NSV) and other genital disease 89 patients attending a genital medicine clinic had vaginal samples examined for conventional pathogens and for quantitative analysis of G vaginalis and aerobic and anaerobic bacterial flora. The overall incidence of G vaginalis was 20%; G vaginalis (mean concentration 7.0 log10/g of secretion) occurred predominantly in patients with NSV (57%) but also in sexual contacts of non-specific urethritis (NSU) (37.5%) and in patients with other conditions (11.8%). G vaginalis is therefore a relatively common isolate in patients with vaginal discharge. The concentration of aerobic and anaerobic bacteria ranged from 4.9-11.0 log10/g of secretion with an anaerobe-to-aerobe ratio of 10:1. Anaerobic bacteria, particularly anaerobic Gram-positive cocci (mean concentrations 7.7 log10/g), were present in patients with NSV and in association with G vaginalis, but they also occurred in other clinical groups and with other pathogens, particularly Trichomonas vaginalis. Anaerobic bacteria may therefore play an important role in the pathogenesis of vaginal infections. PMID:6600955

Calorimetric studies of the growth of anaerobic microbes.

PubMed

Miyake, Hideo; Maeda, Yukiko; Ishikawa, Takashi; Tanaka, Akiyoshi

2016-09-01

This article aims to validate the use of calorimetry to measure the growth of anaerobic microbes. It has been difficult to monitor the growth of strict anaerobes while maintaining optimal growth conditions. Traditionally, optical density and ATP concentration are usually used as measures of the growth of anaerobic microbes. However, to take these measurements it is necessary to extract an aliquot of the culture, which can be difficult while maintaining anaerobic conditions. In this study, calorimetry was used to continuously and nondestructively measure the heat generated by the growth of anaerobic microbes as a function of time. Clostridium acetobutylicum, Clostridium beijerinckii, and Clostridium cellulovorans were used as representative anaerobic microbes. Using a multiplex isothermal calorimeter, we observed that peak time (tp) of C. acetobutylicum heat evolution increased as the inoculation rate decreased. This strong correlation between the inoculation rate and tp showed that it was possible to measure the growth rate of anaerobic microbes by calorimetry. Overall, our results showed that there is a very good correlation between heat evolution and optical density/ATP concentration, validating the use of the method. Copyright © 2016 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

In Situ Enhancement of Anaerobic Microbial Dechlorination of Polychlorinated Dibenzo-p-dioxins and Dibenzofurans in Marine and Estuarine Sediments

DTIC Science & Technology

2006-12-18

Defense. Reference herein to any specific commercial product, process , or service by trade name, trademark, manufacturer, or otherwise, does not...result of a combination of both respiratory and cometabolic processes . For in situ bioremediation, it would be most desirable to stimulate...conditions we examined. While the process has much potential, a key aspect of the technology – the nature and capability of the intrinsic microbial

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.

Anaerobic biorefinery: Current status, challenges, and opportunities.

PubMed

Sawatdeenarunat, Chayanon; Nguyen, Duc; Surendra, K C; Shrestha, Shilva; Rajendran, Karthik; Oechsner, Hans; Xie, Li; Khanal, Samir Kumar

2016-09-01

Anaerobic digestion (AD) has been in use for many decades. To date, it has been primarily aimed at treating organic wastes, mainly manures and wastewater sludge, and industrial wastewaters. However, with the current advancements, a more open mind is required to look beyond these somewhat restricted original applications of AD. Biorefineries are such concepts, where multiple products including chemicals, fuels, polymers etc. are produced from organic feedstocks. The anaerobic biorefinery concept is now gaining increased attention, utilizing AD as the final disposal step. This review aims at evaluating the potential significance of anaerobic biorefineries, including types of feedstocks, uses for the produced energy, as well as sustainable applications of the generated residual digestate. A comprehensive analysis of various types of anaerobic biorefineries has been developed, including both large-scale and household level applications. Finally, future directives are highlighted showing how anaerobic biorefinery concept could impact the bioeconomy in the near future. Copyright © 2016 Elsevier Ltd. All rights reserved.

Anaerobic Digestion. Student Manual. Biological Treatment Process Control.

ERIC Educational Resources Information Center

Carnegie, John W., Ed.

This student manual contains the textual material for a four-lesson unit on anaerobic digestion control. Areas addressed include: (1) anaerobic sludge digestion (considering the nature of raw sludge, purposes of anaerobic digestion, the results of digestion, types of equipment, and other topics); (2) digester process control (considering feeding…

Anaerobic fermentation of glycerol: a path to economic viability for the biofuels industry.

PubMed

Yazdani, Syed Shams; Gonzalez, Ramon

2007-06-01

Although biofuels such as biodiesel and bioethanol represent a secure, renewable and environmentally safe alternative to fossil fuels, their economic viability is a major concern. The implementation of biorefineries that co-produce higher value products along with biofuels has been proposed as a solution to this problem. The biorefinery model would be especially advantageous if the conversion of byproducts or waste streams generated during biofuel production were considered. Glycerol-rich streams generated in large amounts by the biofuels industry, especially during the production of biodiesel, present an excellent opportunity to establish biorefineries. Once considered a valuable 'co-product', crude glycerol is rapidly becoming a 'waste product' with a disposal cost attributed to it. Given the highly reduced nature of carbon in glycerol and the cost advantage of anaerobic processes, fermentative metabolism of glycerol is of special interest. This review covers the anaerobic fermentation of glycerol in microbes and the harnessing of this metabolic process to convert abundant and low-priced glycerol streams into higher value products, thus creating a path to viability for the biofuels industry. Special attention is given to products whose synthesis from glycerol would be advantageous when compared with their production from common sugars.

Electric energy production from food waste: Microbial fuel cells versus anaerobic digestion.

PubMed

Xin, Xiaodong; Ma, Yingqun; Liu, Yu

2018-05-01

A food waste resourceful process was developed by integrating the ultra-fast hydrolysis and microbial fuel cells (MFCs) for energy and resource recovery. Food waste was first ultra-fast hydrolyzed by fungal mash rich in hydrolytic enzymes in-situ produced from food waste. After which, the separated solids were readily converted to biofertilizer, while the liquid was fed to MFCs for direct electricity generation with a conversion efficiency of 0.245 kWh/kg food waste. It was estimated that about 192.5 million kWh of electricity could be produced from the food waste annually generated in Singapore, together with 74,390 tonnes of dry biofertilizer. Compared to anaerobic digestion, the proposed approach was more environmentally friendly and economically viable in terms of both electricity conversion and process cost. It is expected that this study may lead to the paradigm shift in food waste management towards ultra-fast concurrent recovery of resource and electricity with zero-solid discharge. Copyright © 2018 Elsevier Ltd. All rights reserved.

Modeling of simultaneous anaerobic methane and ammonium oxidation in a membrane biofilm reactor.

PubMed

Chen, Xueming; Guo, Jianhua; Shi, Ying; Hu, Shihu; Yuan, Zhiguo; Ni, Bing-Jie

2014-08-19

Nitrogen removal by using the synergy of denitrifying anaerobic methane oxidation (DAMO) and anaerobic ammonium oxidation (Anammox) microorganisms in a membrane biofilm reactor (MBfR) has previously been demonstrated experimentally. In this work, a mathematical model is developed to describe the simultaneous anaerobic methane and ammonium oxidation by DAMO and Anammox microorganisms in an MBfR for the first time. In this model, DAMO archaea convert nitrate, both externally fed and/or produced by Anammox, to nitrite, with methane as the electron donor. Anammox and DAMO bacteria jointly remove the nitrite fed/produced, with ammonium and methane as the electron donor, respectively. The model is successfully calibrated and validated using the long-term (over 400 days) dynamic experimental data from the MBfR, as well as two independent batch tests at different operational stages of the MBfR. The model satisfactorily describes the methane oxidation and nitrogen conversion data from the system. Modeling results show the concentration gradients of methane and nitrogen would cause stratification of the biofilm, where Anammox bacteria mainly grow in the biofilm layer close to the bulk liquid and DAMO organisms attach close to the membrane surface. The low surface methane loadings result in a low fraction of DAMO microorganisms, but the high surface methane loadings would lead to overgrowth of DAMO bacteria, which would compete with Anammox for nitrite and decrease the fraction of Anammox bacteria. The results suggest an optimal methane supply under the given condition should be applied not only to benefit the nitrogen removal but also to avoid potential methane emissions.

[Activity of doripenem against anaerobic bacteria].

PubMed

Dubreuil, L; Neut, C; Mahieux, S; Muller-Serieys, C; Jean-Pierre, H; Marchandin, H; Soussy, C J; Miara, A

2011-04-01

This study examines the activity of doripenem, a new carbapenem compound compared with amoxicillin-clavulanic acid, piperacillin+tazobactam, imipenem, clindamycin and metronidazole against 316 anaerobes. Inoculum preparation and agar dilution method were performed according to the CLSI method for anaerobes (M11A7). At a concentration of 4μg/ml doripenem and imipenem (IMP) inhibited 122 (96 %) and 126 (99 %) strains of the Bacteroides fragilis group, respectively. In contrast, doripenem appeared more potent than IMP against Gram-positive anaerobes inhibiting at the same concentration of 4μg/ml 145/145 strains (100 %) versus 115/145 for IMP (79.3 %). Against 316 anaerobic strains, the carbapenem doripenem had an MIC(50) of 0.25μg/ml and an MIC(90) of 2μg/ml. Results were similar to those for imipenem (MIC(50) of 0.125μg/ml and MIC(90) of 4μg/ml). If we consider the resistant breakpoints of the two carbapenems as defined by EUCAST, the resistance rate for doripenem (MIC>4μg/ml) 1.6 % is similar to that of imipenem (MIC>8μg/ml) 1.3 %. Thus independently of the PK/PD parameters the two carbapenems demonstrated very close activity; doripenem was more potent on Gram-positive anaerobes and slightly less potent against Gram-negative anaerobes mainly the B. fragilis group. Further clinical studies are needed to assess its usefulness in patients. Copyright © 2010 Elsevier Masson SAS. All rights reserved.

Biochemistry and Evolution of Anaerobic Energy Metabolism in Eukaryotes

PubMed Central

Müller, Miklós; Mentel, Marek; van Hellemond, Jaap J.; Henze, Katrin; Woehle, Christian; Gould, Sven B.; Yu, Re-Young; van der Giezen, Mark

2012-01-01

Summary: Major insights into the phylogenetic distribution, biochemistry, and evolutionary significance of organelles involved in ATP synthesis (energy metabolism) in eukaryotes that thrive in anaerobic environments for all or part of their life cycles have accrued in recent years. All known eukaryotic groups possess an organelle of mitochondrial origin, mapping the origin of mitochondria to the eukaryotic common ancestor, and genome sequence data are rapidly accumulating for eukaryotes that possess anaerobic mitochondria, hydrogenosomes, or mitosomes. Here we review the available biochemical data on the enzymes and pathways that eukaryotes use in anaerobic energy metabolism and summarize the metabolic end products that they generate in their anaerobic habitats, focusing on the biochemical roles that their mitochondria play in anaerobic ATP synthesis. We present metabolic maps of compartmentalized energy metabolism for 16 well-studied species. There are currently no enzymes of core anaerobic energy metabolism that are specific to any of the six eukaryotic supergroup lineages; genes present in one supergroup are also found in at least one other supergroup. The gene distribution across lineages thus reflects the presence of anaerobic energy metabolism in the eukaryote common ancestor and differential loss during the specialization of some lineages to oxic niches, just as oxphos capabilities have been differentially lost in specialization to anoxic niches and the parasitic life-style. Some facultative anaerobes have retained both aerobic and anaerobic pathways. Diversified eukaryotic lineages have retained the same enzymes of anaerobic ATP synthesis, in line with geochemical data indicating low environmental oxygen levels while eukaryotes arose and diversified. PMID:22688819

Anaerobic Metabolism and Bioremediation of Explosives-Contaminated Soil

NASA Astrophysics Data System (ADS)

Boopathy, Raj

Nitroaromatic compounds pollute soil, water, and food via use of pesticides, plastics, pharmaceuticals, landfill dumping of industrial wastes, and the military use of explosives. Biotransformation of trinitrotoluene and other nitroaromatics by aerobic bacteria in the laboratory has been frequently reported, but the anaerobic bacterial metabolism of nitroaromatics has not been studied as extensively perhaps due to the difficulty in working with anaerobic cultures and the slow growth of anaerobes. Sulfate-reducing and methanogenic bacteria can metabolize nitroaromatic compounds under anaerobic conditions if appropriate electron donors and electron acceptors are present in the environment.

Anaerobic Metabolism in the N-Limited Green Alga Selenastrum minutum: III. Alanine Is the Product of Anaerobic Ammonium Assimilation.

PubMed

Vanlerberghe, G C; Joy, K W; Turpin, D H

1991-02-01

We have determined the flow of (15)N into free amino acids of the N-limited green alga Selenastrum minutum (Naeg.) Collins after addition of (15)NH(4) (+) to aerobic or anaerobic cells. Under aerobic conditions, only a small proportion of the N assimilated was retained in the free amino acid pool. However, under anaerobic conditions almost all assimilated NH(4) (+) accumulates in alanine. This is a unique feature of anaerobic NH(4) (+) assimilation. The pathway of carbon flow to alanine results in the production of ATP and reductant which matches exactly the requirements of NH(4) (+) assimilation. Alanine synthesis is therefore an excellent strategy to maintain energy and redox balance during anaerobic NH(4) (+) assimilation.

Cellulosic ethanol production via consolidated bioprocessing by a novel thermophilic anaerobic bacterium isolated from a Himalayan hot spring.

PubMed

Singh, Nisha; Mathur, Anshu S; Tuli, Deepak K; Gupta, Ravi P; Barrow, Colin J; Puri, Munish

2017-01-01

Cellulose-degrading thermophilic anaerobic bacterium as a suitable host for consolidated bioprocessing (CBP) has been proposed as an economically suited platform for the production of second-generation biofuels. To recognize the overall objective of CBP, fermentation using co-culture of different cellulolytic and sugar-fermenting thermophilic anaerobic bacteria has been widely studied as an approach to achieving improved ethanol production. We assessed monoculture and co-culture fermentation of novel thermophilic anaerobic bacterium for ethanol production from real substrates under controlled conditions. In this study, Clostridium sp. DBT-IOC-C19, a cellulose-degrading thermophilic anaerobic bacterium, was isolated from the cellulolytic enrichment cultures obtained from a Himalayan hot spring. Strain DBT-IOC-C19 exhibited a broad substrate spectrum and presented single-step conversion of various cellulosic and hemicellulosic substrates to ethanol, acetate, and lactate with ethanol being the major fermentation product. Additionally, the effect of varying cellulose concentrations on the fermentation performance of the strain was studied, indicating a maximum cellulose utilization ability of 10 g L -1 cellulose. Avicel degradation kinetics of the strain DBT-IOC-C19 displayed 94.6% degradation at 5 g L -1 and 82.74% degradation at 10 g L -1 avicel concentration within 96 h of fermentation. In a comparative study with Clostridium thermocellum DSM 1313, the ethanol and total product concentrations were higher by the newly isolated strain on pretreated rice straw at an equivalent substrate loading. Three different co-culture combinations were used on various substrates that presented two-fold yield improvement than the monoculture during batch fermentation. This study demonstrated the direct fermentation ability of the novel thermophilic anaerobic bacteria on various cellulosic and hemicellulosic substrates into ethanol without the aid of any exogenous enzymes

Techniques for controlling variability in gram staining of obligate anaerobes.

PubMed Central

Johnson, M J; Thatcher, E; Cox, M E

1995-01-01

Identification of anaerobes recovered from clinical samples is complicated by the fact that certain gram-positive anaerobes routinely stain gram negative; Peptostreptococcus asaccharolyticus, Eubacterium plautii, Clostridium ramosum, Clostridium symbiosum, and Clostridium clostridiiforme are among the nonconformists with regard to conventional Gram-staining procedures. Accurate Gram staining of American Type Culture Collection strains of these anaerobic bacteria is possible by implementing fixing and staining techniques within a gloveless anaerobic chamber. Under anaerobic conditions, gram-positive staining occurred in all test organisms with "quick" fixing techniques with both absolute methanol and formalin. The results support the hypothesis that, when anaerobic bacteria are exposed to oxygen, a breakdown of the physical integrity of the cell wall occurs, introducing Gram stain variability in gram-positive anaerobes. PMID:7538512

The challenges of anaerobic digestion and the role of biochar in optimizing anaerobic digestion.

PubMed

Fagbohungbe, Michael O; Herbert, Ben M J; Hurst, Lois; Ibeto, Cynthia N; Li, Hong; Usmani, Shams Q; Semple, Kirk T

2017-03-01

Biochar, like most other adsorbents, is a carbonaceous material, which is formed from the combustion of plant materials, in low-zero oxygen conditions and results in a material, which has the capacity to sorb chemicals onto its surfaces. Currently, research is being carried out to investigate the relevance of biochar in improving the soil ecosystem, digestate quality and most recently the anaerobic digestion process. Anaerobic digestion (AD) of organic substrates provides both a sustainable source of energy and a digestate with the potential to enhance plant growth and soil health. In order to ensure that these benefits are realised, the anaerobic digestion system must be optimized for process stability and high nutrient retention capacity in the digestate produced. Substrate-induced inhibition is a major issue, which can disrupt the stable functioning of the AD system reducing microbial breakdown of the organic waste and formation of methane, which in turn reduces energy output. Likewise, the spreading of digestate on land can often result in nutrient loss, surface runoff and leaching. This review will examine substrate inhibition and their impact on anaerobic digestion, nutrient leaching and their environmental implications, the properties and functionality of biochar material in counteracting these challenges. Copyright © 2016 Elsevier Ltd. All rights reserved.

Anaerobic Treatment of Palm Oil Mill Effluent in Pilot-Scale Anaerobic EGSB Reactor

PubMed Central

Mahmood, Qaisar; Qiu, Jiang-Ping; Li, Yin-Sheng; Chang, Yoon-Seong; Li, Xu-Dong

2015-01-01

Large volumes of untreated palm oil mill effluent (POME) pose threat to aquatic environment due to the presence of very high organic content. The present investigation involved two pilot-scale anaerobic expanded granular sludge bed (EGSB) reactors, continuously operated for 1 year to treat POME. Setting HRT at 9.8 d, the anaerobic EGSB reactors reduced COD from 71179 mg/L to 12341 mg/L and recycled half of sludge by a dissolved air flotation (DAF). The average effluent COD was 3587 mg/L with the consistent COD removal efficiency of 94.89%. Adding cationic polymer (PAM) dose of 30 mg/L to DAF unit and recycling its half of sludge caused granulation of anaerobic sludge. Bacilli and small coccid bacteria were the dominant microbial species of the reactor. The reactor produced 27.65 m3 of biogas per m3 of POME which was utilized for electricity generation. PMID:26167485

21 CFR 866.2120 - Anaerobic chamber.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Anaerobic chamber. 866.2120 Section 866.2120 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Microbiology Devices § 866.2120 Anaerobic chamber. (a...

21 CFR 866.2120 - Anaerobic chamber.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Anaerobic chamber. 866.2120 Section 866.2120 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Microbiology Devices § 866.2120 Anaerobic chamber. (a...

21 CFR 866.2120 - Anaerobic chamber.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Anaerobic chamber. 866.2120 Section 866.2120 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Microbiology Devices § 866.2120 Anaerobic chamber. (a...

21 CFR 866.2120 - Anaerobic chamber.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Anaerobic chamber. 866.2120 Section 866.2120 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Microbiology Devices § 866.2120 Anaerobic chamber. (a...

21 CFR 866.2120 - Anaerobic chamber.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Anaerobic chamber. 866.2120 Section 866.2120 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Microbiology Devices § 866.2120 Anaerobic chamber. (a...

[Anaerobic digestion of animal manure contaminated by tetracyclines].

PubMed

Tong, Zi-Lin; Liu, Yuan-Lu; Hu, Zhen-Hu; Yuan, Shou-Jun

2012-03-01

Anaerobic digestion of pig manure spiked with tetracycline (TC) and chlortetracycline (CTC) and the degradation of the two antibiotics during the anaerobic digestion at 35 degrees C were investigated. The results indicate that propionate was the main volatile fatty acid produced during the anaerobic digestion followed by acetate. Compared with the CTC addition, TC + CTC addition showed obvious inhibitory effect on the hydrolysis and acidification of easily digestible organic components of pig manure. The cumulative methane production of TC, CTC, TC + CTC and CK2 during anaerobic digestion was 386.4 mL, 406.0 mL, 412.1 mL and 464.6 mL, respectively. Degradation of TC and CTC followed the first-order kinetic equation. The half-life of TC and CTC was 14-18 days and 10 days, respectively. After the treatment of 45-day anaerobic digestion, the degradation efficiency of TC was 88.6%-91.6% with 97.7%-98.2% of CTC. Therefore, anaerobic digestion shows the benefit on the management of animal manures contaminated by tetracyclines.

The effect of transient loading on the performance of a mesophilic anaerobic contact reactor at constant feed strength.

PubMed

Sentürk, Elif; Ince, Mahir; Engin, Guleda Onkal

2012-12-15

Anaerobic contact reactor is a high rate anaerobic process consisting of an agitated reactor and a solids settling tank for recycling. It was proved earlier that this type of reactor design offers highly efficient performance in the conversion of organic matter to biogas. In this study, the effect of transient loading on reactor performance in terms of a number of key intermediates and parameters such as, COD removal, pH and alkalinity change, VFAs, effluent MLSS concentration and biogas efficiency over time was examined. For this purpose, a step increase of organic loading rate from 3.35kg COD/m(3)day to 15.61kg COD/m(3)day was employed. The hydraulic retention time decreased to a value of 8.42h by an increase in the influent flow-rate during the transient loading. It was observed that the mesophilic anaerobic contact reactor (MACR) was quite resistant to large transient shocks. The reactor recovered back to its baseline performance only in 15h after the shock loading was stopped. Hence, it can be concluded that this type of reactor design has a high potential in treating food processing wastewaters with varying flow characteristics. Copyright © 2012 Elsevier B.V. All rights reserved.

[Distribution and removal of anaerobic antibiotic resistant bacteria during mesophilic anaerobic digestion of sewage sludge].

PubMed

Tong, Juan; Wang, Yuan-Yue; Wei Yuan, Song

2014-10-01

Sewage sludge is one of the major sources that releasing antibiotic resistant bacteria (ARB) and antibiotic resistant genes (ARG) into the environment since it contains large amount of ARB, but there is little information about the fate of the anaerobic ARB in the anaerobic digestion of sewage sludge. Therefore, the distribution, removal and seasonal changes of tetracycline and β-lactam antibiotics resistant bacteria in the mesophilic egg-shaped digesters of a municipal wastewater treatment plant were investigated for one year in this study. Results showed that there were higher amounts of ARB and higher resistance rate of β-lactam antibiotics than that of tetracycline antibiotics in the sewage sludge. All ARB could be significantly reduced during the mesophilic anaerobic digestion process by 1.48-1.64 log unit (P < 0.05). Notably, the ampicillin and cephalothin resistance rates were significantly increased after anaerobic digestion by 12.0% and 14.3%, respectively (P < 0.05). The distribution of ARB in the sewage sludge had seasonal change characteristics. Except for chlorotetracycline resistant bacteria, there were more ARB in the sewage sludge in cold season than in warm season (P < 0.05).

Prospective study of the clinical performance of three BACTEC media in a modern emergency department: Plus Aerobic/F, Plus Anaerobic/F, and Anaerobic Lytic/F.

PubMed

Rocchetti, Andrea; Di Matteo, Luigi; Bottino, Paolo; Foret, Benjamin; Gamalero, Elisa; Calabresi, Alessandra; Guido, Gianluca; Casagranda, Ivo

2016-11-01

The performance of 3 blood culture bottles (BACTEC Plus Aerobic/F, Plus Anaerobic/F, and Anaerobic Lytic/F) were analyzed with clinical specimens collected from 688 Emergency Department patients. A total of 270 strains belonging to 33 species were identified, with E. coli and S. aureus as the most frequently detected. Overall recovery rate (RR) of bacteria and yeast was equivalent in the Plus Aerobic/F vials (208 of 270 isolates; 77.0%) and Anaerobic Lytic/F vials (206 isolates; 76.3%) and significantly better than in the Plus Anaerobic/F vials (189 isolates; 70.0%). Median time to detection (TTD) was earliest with the Anaerobic Lytic/F vials (12.0h) compared with the Plus Aerobic/F (14.6h) and Plus Anaerobic/F vials (15.4h). Positivity rate (PR) was similar for Anaerobic Lytic/F vials (76.9%) and Plus Aerobic/F vials (76.5%), but better if compared with Plus Anaerobic/F vials (69.4%). The PR and TTD for the combination of Plus Aerobic/F with Anaerobic Lytic/F (94.5% and 12.3h, respectively) was significantly better than with Plus Aerobic/F with Plus Anaerobic/F (87.8% and 14.1h). Copyright © 2016 Elsevier B.V. All rights reserved.

Anaerobic Threshold and Salivary α-amylase during Incremental Exercise.

PubMed

Akizuki, Kazunori; Yazaki, Syouichirou; Echizenya, Yuki; Ohashi, Yukari

2014-07-01

[Purpose] The purpose of this study was to clarify the validity of salivary α-amylase as a method of quickly estimating anaerobic threshold and to establish the relationship between salivary α-amylase and double-product breakpoint in order to create a way to adjust exercise intensity to a safe and effective range. [Subjects and Methods] Eleven healthy young adults performed an incremental exercise test using a cycle ergometer. During the incremental exercise test, oxygen consumption, carbon dioxide production, and ventilatory equivalent were measured using a breath-by-breath gas analyzer. Systolic blood pressure and heart rate were measured to calculate the double product, from which double-product breakpoint was determined. Salivary α-amylase was measured to calculate the salivary threshold. [Results] One-way ANOVA revealed no significant differences among workloads at the anaerobic threshold, double-product breakpoint, and salivary threshold. Significant correlations were found between anaerobic threshold and salivary threshold and between anaerobic threshold and double-product breakpoint. [Conclusion] As a method for estimating anaerobic threshold, salivary threshold was as good as or better than determination of double-product breakpoint because the correlation between anaerobic threshold and salivary threshold was higher than the correlation between anaerobic threshold and double-product breakpoint. Therefore, salivary threshold is a useful index of anaerobic threshold during an incremental workload.

[Application of anaerobic bacteria detection in oral and maxillofacial infection].

PubMed

Bao, Zhen-ying; Lin, Qin; Meng, Yan-hong; He, Chun; Su, Jia-zeng; Peng, Xin

2016-02-18

To investigate the distribution and drug resistance of anaerobic bacteria in the patients with oral and maxillofacial infection. Aerobic and anaerobic bacteria cultures from 61 specimens of pus from the patients with oral and maxillofacial infection in the Department of Oral and Maxillofacial Surgery, Peking University School of Stomatology were identified. The culture type was evaluated by API 20A kit and drug resistance test was performed by Etest method. The clinical data and antibacterial agents for the treatment of the 61 cases were collected, and the final outcomes were recorded. The bacteria cultures were isolated from all the specimens, with aerobic bacteria only in 6 cases (9.8%), anaerobic bacteria only in 7 cases (11.5%), and both aerobic and anaerobic bacteria in 48 cases (78.7%). There were 55 infected cases (90.2%) with anaerobic bacteria, and 81 anaerobic bacteria stains were isolated. The highest bacteria isolation rate of Gram positive anaerobic bacteria could be found in Peptostreptococcus, Bifidobacterium and Pemphigus propionibacterium. No cefoxitin, amoxicillin/carat acid resistant strain was detected in the above three Gram positive anaerobic bacteria. The highest bacteria isolation rate of Gram negative anaerobic bacteria could be detected in Porphyromonas and Prevotella. No metronidazole, cefoxitin, amoxicillin/carat acid resistant strain was found in the two Gram negative anaerobic bacteria. In the study, 48 patients with oral and maxillofacial infection were treated according to the results of drug resistance testing, and the clinical cure rate was 81.3%. Mixed aerobic and anaerobic bacteria cultures are very common in most oral and maxillofacial infection patients. Anaerobic bacteria culture and drug resistance testing play an important role in clinical treatment.

Anaerobic energy metabolism in unicellular photosynthetic eukaryotes.

PubMed

Atteia, Ariane; van Lis, Robert; Tielens, Aloysius G M; Martin, William F

2013-02-01

Anaerobic metabolic pathways allow unicellular organisms to tolerate or colonize anoxic environments. Over the past ten years, genome sequencing projects have brought a new light on the extent of anaerobic metabolism in eukaryotes. A surprising development has been that free-living unicellular algae capable of photoautotrophic lifestyle are, in terms of their enzymatic repertoire, among the best equipped eukaryotes known when it comes to anaerobic energy metabolism. Some of these algae are marine organisms, common in the oceans, others are more typically soil inhabitants. All these species are important from the ecological (O(2)/CO(2) budget), biotechnological, and evolutionary perspectives. In the unicellular algae surveyed here, mixed-acid type fermentations are widespread while anaerobic respiration, which is more typical of eukaryotic heterotrophs, appears to be rare. The presence of a core anaerobic metabolism among the algae provides insights into its evolutionary origin, which traces to the eukaryote common ancestor. The predicted fermentative enzymes often exhibit an amino acid extension at the N-terminus, suggesting that these proteins might be compartmentalized in the cell, likely in the chloroplast or the mitochondrion. The green algae Chlamydomonas reinhardtii and Chlorella NC64 have the most extended set of fermentative enzymes reported so far. Among the eukaryotes with secondary plastids, the diatom Thalassiosira pseudonana has the most pronounced anaerobic capabilities as yet. From the standpoints of genomic, transcriptomic, and biochemical studies, anaerobic energy metabolism in C. reinhardtii remains the best characterized among photosynthetic protists. This article is part of a Special Issue entitled: The evolutionary aspects of bioenergetic systems. Copyright © 2012 Elsevier B.V. All rights reserved.

ANAEROBIC BIOTRANSFORMATION OF CONTAMINANTS IN THE SUBSURFACE

EPA Science Inventory

Anaerobic conditions predominate in contaminated aquifers and are not uncommon in noncontaminated areas. Comparatively little is known about degradative processes and nutrient cycling under anaerobic conditions. However, it is apparent these processes are fundamentally differen...

Anaerobic metabolism in the N-limited green alga Selenastrum minutum. 3. Alanine is the product of anaerobic ammonium assimilation

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

Vanlerberghe, G.C.; Turpin, D.H.; Joy, K.W.

The authors have determined the flow of {sup 15}N into free amino acids of the N-limited green alga Selenastrum minutum (Naeg.) Collins after addition of {sup 15}NH{sub 4}{sup +} to aerobic or anaerobic cells. Under aerobic conditions, only a small proportion of the N assimilated was retained in the free amino acid pool. However, under anaerobic conditions almost all assimilated NH{sub 4}{sup +} accumulates in alanine. This is a unique feature of anaerobic NH{sub 4}{sup +} assimilation. The pathway of carbon flow to alanine results in the production of ATP and reductant which matches exactly the requirements of NH{sub 4}{supmore » +} assimilation. Alanine synthesis is therefore an excellent strategy to maintain energy and redox balance during anaerobic NH{sub 4}{sup +} assimilation.« less

Anaerobic bacteria that dechlorinate perchloroethene.

PubMed Central

Fathepure, B Z; Nengu, J P; Boyd, S A

1987-01-01

In this study, we identified specific cultures of anaerobic bacteria that dechlorinate perchlorethene (PCE). The bacteria that significantly dechlorinated PCE were strain DCB-1, an obligate anaerobe previously shown to dechlorinate chlorobenzoate, and two strains of Methanosarcina. The rate of PCE dechlorination by DCB-1 compared favorably with reported rates of trichloroethene bio-oxidation by methanotrophs. Even higher PCE dechlorination rates were achieved when DCB-1 was grown in a methanogenic consortium. PMID:3426224

Anaerobic work calculated in cycling time trials of different length.

PubMed

Mulder, Roy C; Noordhof, Dionne A; Malterer, Katherine R; Foster, Carl; de Koning, Jos J

2015-03-01

Previous research showed that gross efficiency (GE) declines during exercise and therefore influences the expenditure of anaerobic and aerobic resources. To calculate the anaerobic work produced during cycling time trials of different length, with and without a GE correction. Anaerobic work was calculated in 18 trained competitive cyclists during 4 time trials (500, 1000, 2000, and 4000-m). Two additional time trials (1000 and 4000 m) that were stopped at 50% of the corresponding "full" time trial were performed to study the rate of the decline in GE. Correcting for a declining GE during time-trial exercise resulted in a significant (P<.001) increase in anaerobically attributable work of 30%, with a 95% confidence interval of [25%, 36%]. A significant interaction effect between calculation method (constant GE, declining GE) and distance (500, 1000, 2000, 4000 m) was found (P<.001). Further analysis revealed that the constant-GE calculation method was different from the declining method for all distances and that anaerobic work calculated assuming a constant GE did not result in equal values for anaerobic work calculated over different time-trial distances (P<.001). However, correcting for a declining GE resulted in a constant value for anaerobically attributable work (P=.18). Anaerobic work calculated during short time trials (<4000 m) with a correction for a declining GE is increased by 30% [25%, 36%] and may represent anaerobic energy contributions during high-intensity exercise better than calculating anaerobic work assuming a constant GE.

Microbial Internal Storage Alters the Carbon Transformation in Dynamic Anaerobic Fermentation.

PubMed

Ni, Bing-Jie; Batstone, Damien; Zhao, Bai-Hang; Yu, Han-Qing

2015-08-04

Microbial internal storage processes have been demonstrated to occur and play an important role in activated sludge systems under both aerobic and anoxic conditions when operating under dynamic conditions. High-rate anaerobic reactors are often operated at a high volumetric organic loading and a relatively dynamic profile, with large amounts of fermentable substrates. These dynamic operating conditions and high catabolic energy availability might also facilitate the formation of internal storage polymers by anaerobic microorganisms. However, so far information about storage under anaerobic conditions (e.g., anaerobic fermentation) as well as its consideration in anaerobic process modeling (e.g., IWA Anaerobic Digestion Model No. 1, ADM1) is still sparse. In this work, the accumulation of storage polymers during anaerobic fermentation was evaluated by batch experiments using anaerobic methanogenic sludge and based on mass balance analysis of carbon transformation. A new mathematical model was developed to describe microbial storage in anaerobic systems. The model was calibrated and validated by using independent data sets from two different anaerobic systems, with significant storage observed, and effectively simulated in both systems. The inclusion of the new anaerobic storage processes in the developed model allows for more successful simulation of transients due to lower accumulation of volatile fatty acids (correction for the overestimation of volatile fatty acids), which mitigates pH fluctuations. Current models such as the ADM1 cannot effectively simulate these dynamics due to a lack of anaerobic storage mechanisms.

Economic and environmental analysis of four different configurations of anaerobic digestion for food waste to energy conversion using LCA for: a food service provider case study.

PubMed

Franchetti, Matthew

2013-07-15

The US disposes of more than 34 million tons of food waste in landfills per year. As this food waste decomposes it generates methane gas and negatively contributes to global warming. Diverting theses organic food wastes from landfills and to emerging technologies will prevent these wastes and greenhouse gas emissions while at the same time generating a source renewable energy by collecting the emitted gases. From a waste prevention standpoint, instead of the food waste decomposing at local landfills, it is being converted into an energy source and the by-product may be used as a fertilizer (Fine and Hadas, 2012). The purpose of this study was to compare four different configurations of anaerobic digestion of organic waste to energy technologies from an economic, energy, and emissions standpoint using LCA via a case study at a large food services provider in Northwest Ohio, USA. The technologies studied included two-stage anaerobic digestion system using ultrasound pre-treating, two stage continuous combined thermophilic acidogenic hydrogenesis and mesophilic with recirculation of the digested sludge, long-term anaerobic digestion of food waste stabilized by trace elements, and single stage anaerobic digestion. Using LCA, these scenarios were compared to landfill disposal of the food waste. The findings from the case study indicated that implementing on-site waste to energy systems will result in lower operation costs and lower environmental impacts. In addition, a standardized environmental and economic comparison of competing food waste to energy technologies is provided. Copyright © 2013 Elsevier Ltd. All rights reserved.

Anaerobic digestion performance of sweet potato vine and animal manure under wet, semi-dry, and dry conditions.

PubMed

Zhang, Enlan; Li, Jiajia; Zhang, Keqiang; Wang, Feng; Yang, Houhua; Zhi, Suli; Liu, Guangqing

2018-03-22

Sweet potato vine (SPV) is an abundant agricultural waste, which is easy to obtain at low cost and has the potential to produce clean energy via anaerobic digestion (AD). The main objectives of this study were to reveal methane production and process stability of SPV and the mixtures with animal manure under various total solid conditions, to verify synergetic effect in co-digestion of SPV and manure in AD systems, and to determine the kinetics characteristics during the full AD process. The results showed that SPV was desirable feedstock for AD with 200.22 mL/g VS added of methane yield in wet anaerobic digestion and 12.20 L methane /L working volume in dry anaerobic digestion (D-AD). Synergistic effects were found in semi-dry anaerobic digestion and D-AD with each two mixing feedstock. In contrast with SPV mono-digestion, co-digestion with manure increased methane yield within the range of 14.34-49.11% in different AD digesters. The values of final volatile fatty acids to total alkalinity (TA) were below 0.4 and the values of final pH were within the range of 7.4-8.2 in all the reactors, which supported a positive relationship between carbohydrate hydrolysis and methanogenesis during AD process. The mathematical modified first order model was applied to estimate substrate biodegradability and methane production potential well with conversion constant ranged from 0.0003 to 0.0953 1/day, which indicated that co-digestion increased hydrolysis efficiency and metabolic activity. This work provides useful information to improve the utilization and stability of digestion using SPV and livestock or poultry manure as substrates.

Ethanol and anaerobic conditions reversibly inhibit commercial cellulase activity in thermophilic simultaneous saccharification and fermentation (tSSF)

PubMed Central

2012-01-01

Background A previously developed mathematical model of low solids thermophilic simultaneous saccharification and fermentation (tSSF) with Avicel was unable to predict performance at high solids using a commercial cellulase preparation (Spezyme CP) and the high ethanol yield Thermoanaerobacterium saccharolyticum strain ALK2. The observed hydrolysis proceeded more slowly than predicted at solids concentrations greater than 50 g/L Avicel. Factors responsible for this inaccuracy were investigated in this study. Results Ethanol dramatically reduced cellulase activity in tSSF. At an Avicel concentration of 20 g/L, the addition of ethanol decreased conversion at 96 hours, from 75% in the absence of added ethanol down to 32% with the addition of 34 g/L initial ethanol. This decrease is much greater than expected based on hydrolysis inhibition results in the absence of a fermenting organism. The enhanced effects of ethanol were attributed to the reduced, anaerobic conditions of tSSF, which were shown to inhibit cellulase activity relative to hydrolysis under aerobic conditions. Cellulose hydrolysis in anaerobic conditions was roughly 30% slower than in the presence of air. However, this anaerobic inhibition was reversed by exposing the cellulase enzymes to air. Conclusion This work demonstrates a previously unrecognized incompatibility of enzymes secreted by an aerobic fungus with the fermentation conditions of an anaerobic bacterium and suggests that enzymes better suited to industrially relevant fermentation conditions would be valuable. The effects observed may be due to inactivation or starvation of oxygen dependent GH61 activity, and manipulation or replacement of this activity may provide an opportunity to improve biomass to fuel process efficiency. PMID:22703989

The Influence of Hydration on Anaerobic Performance: A Review

ERIC Educational Resources Information Center

Kraft, Justin A.; Green, James M.; Bishop, Phillip A.; Richardson, Mark T.; Neggers, Yasmin H.; Leeper, James D.

2012-01-01

This review examines the influence of dehydration on muscular strength and endurance and on single and repeated anaerobic sprint bouts. Describing hydration effects on anaerobic performance is difficult because various exercise modes are dominated by anaerobic energy pathways, but still contain inherent physiological differences. The critical…

Anaerobic electron acceptor chemotaxis in Shewanella putrefaciens

NASA Technical Reports Server (NTRS)

Nealson, K. H.; Moser, D. P.; Saffarini, D. A.

1995-01-01

Shewanella putrefaciens MR-1 can grow either aerobically or anaerobically at the expense of many different electron acceptors and is often found in abundance at redox interfaces in nature. Such redox interfaces are often characterized by very strong gradients of electron acceptors resulting from rapid microbial metabolism. The coincidence of S. putrefaciens abundance with environmental gradients prompted an examination of the ability of MR-1 to sense and respond to electron acceptor gradients in the laboratory. In these experiments, taxis to the majority of the electron acceptors that S. putrefaciens utilizes for anaerobic growth was seen. All anaerobic electron acceptor taxis was eliminated by the presence of oxygen, nitrate, nitrite, elemental sulfur, or dimethyl sulfoxide, even though taxis to the latter was very weak and nitrate and nitrite respiration was normal in the presence of dimethyl sulfoxide. Studies with respiratory mutants of MR-1 revealed that several electron acceptors that could not be used for anaerobic growth nevertheless elicited normal anaerobic taxis. Mutant M56, which was unable to respire nitrite, showed normal taxis to nitrite, as well as the inhibition of taxis to other electron acceptors by nitrite. These results indicate that electron acceptor taxis in S. putrefaciens does not conform to the paradigm established for Escherichia coli and several other bacteria. Carbon chemo-taxis was also unusual in this organism: of all carbon compounds tested, the only positive response observed was to formate under anaerobic conditions.

Mechanism of quinolone resistance in anaerobic bacteria.

PubMed

Oh, H; Edlund, C

2003-06-01

Several recently developed quinolones have excellent activity against a broad range of aerobic and anaerobic bacteria and are thus potential drugs for the treatment of serious anaerobic and mixed infections. Resistance to quinolones is increasing worldwide, but is still relatively infrequent among anaerobes. Two main mechanisms, alteration of target enzymes (gyrase and topoisomerase IV) caused by chromosomal mutations in encoding genes, or reduced intracellular accumulation due to increased efflux of the drug, are associated with quinolone resistance. These mechanisms have also been found in anaerobic species. High-level resistance to the newer broad-spectrum quinolones often requires stepwise mutations in target genes. The increasing emergence of resistance among anaerobes may be a consequence of previous widespread use of quinolones, which may have enriched first-step mutants in the intestinal tract. Quinolone resistance in the Bacteroides fragilis group strains is strongly correlated with amino acid substitutions at positions 82 and 86 in GyrA (equivalent to positions 83 and 87 of Escherichia coli). Several studies have indicated that B. fragilis group strains possess efflux pump systems that actively expel quinolones, leading to resistance. DNA gyrase seems also to be the primary target for quinolones in Clostridium difficile, since amino acid substitutions in GyrA and GyrB have been detected in resistant strains. To what extent other mechanisms, such as mutational events in other target genes or alterations in outer-membrane proteins, contribute to resistance among anaerobes needs to be further investigated.

Assessment of anaerobic biodegradability of five different solid organic wastes

NASA Astrophysics Data System (ADS)

Kristanto, Gabriel Andari; Asaloei, Huinny

2017-03-01

The concept of waste to energy emerges as an alternative solution to increasing waste generation and energy crisis. In the waste to energy concept, waste will be used to produce renewable energy through thermochemical, biochemical, and physiochemical processes. In an anaerobic digester, organic matter brake-down due to anaerobic bacteria produces methane gas as energy source. The organic waste break-down is affected by various characteristics of waste components, such as organic matter content (C, N, O, H, P), solid contents (TS and VS), nutrients ratio (C/N), and pH. This research aims to analyze biodegradability and potential methane production (CH4) from organic waste largely available in Indonesia. Five solid wastes comprised of fecal sludge, cow rumen, goat farm waste, traditional market waste, and tofu dregs were analyzed which showed tofu dregs as waste with the highest rate of biodegradability compared to others since the tofu dregs do not contain any inhibitor which is lignin, have 2.7%VS, 14 C/N ratios and 97.3% organic matter. The highest cumulative methane production known as Biochemical Methane Potential was achieved by tofu dregs with volume of 77 ml during 30-day experiment which then followed by cow rumen, goat farm waste, and traditional market waste. Subsequently, methane productions were calculated through percentage of COD reduction, which showed the efficiency of 99.1% that indicates complete conversion of the high organic matter into methane.

Methane production by anaerobic digestion of Bermuda grass

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

Klass, D.L.; Ghosh, S.

1981-01-01

Bermuda grass (Cynodon dactylon) is one of the high-yield warm-season grasses that has been suggested as a promising raw material for conversion to methane. Experimental work performed with laboratory digesters to study the anaerobic digestion of Coastal Bermuda grass harvested in Louisiana and having a C/N ratio of 24 is described. Methane yields of about 1.9 SCF/lb of volatile solids (VS) added were observed under conventional mesophilic high-rate conditions. When supplemental nitrogen additions were made, the methane yields increased. This observation along with the compositional data compiled on the grass used in this work indicated that the nitrogen content ofmore » the unsupplemented grass was insufficient to sustain high-rate digestion at the higher yield level. However, as the C/N ratio was reduced by addition of ammonium chloride, the methane yield continually increased up to 3.5 SCF/lb added at the lowest C/N ratio examined (6.3) even after relatively high concentrations of ammonium nitrogen were measured in the effluent. It appears that the added nutrient had a stimulatory effect on methane production above the point where nitrogen was not limiting. Thermophilic digestion with supplemental nitrogen additions afforded methane yields of about 2.7 SCF/lb VS added. Carbon and energy balances were calculated and the relative biodegradabilities of the organics were estimated. It was concluded from this work that Coastal Bermuda grass can be converted to high-methane gas under conventional anaerobic digestion conditions. The performance of the particular lot of grass studied was substantially improved by supplemental nitrogen additions. (Refs. 12).« less

Detection and quantification of long chain fatty acids in liquid and solid samples and its relevance to understand anaerobic digestion of lipids.

PubMed

Neves, L; Pereira, M A; Mota, M; Alves, M M

2009-01-01

A method for long chain fatty acids (LCFA) extraction, identification and further quantification by gas chromatography was developed and its application to liquid and solid samples collected from anaerobic digesters was demonstrated. After validation, the usefulness of this method was demonstrated in a cow manure digester receiving pulses of an industrial effluent containing high lipid content. From the LCFA analysis data it was showed that the conversion of oleic acid, the main LCFA fed to the reactor, by the adapted biomass became faster and more effective along the successive pulses. Conversely, the accumulation of palmitic acid in the solid phase suggests that degradation of this LCFA, under these conditions, is less effective.

Application of Methanobrevibacter acididurans in anaerobic digestion.

PubMed

Savant, D V; Ranade, D R

2004-01-01

To operate anaerobic digesters successfully under acidic conditions, hydrogen utilizing methanogens which can grow efficiently at low pH and tolerate high volatile fatty acids (VFA) are desirable. An acid tolerant hydrogenotrophic methanogen viz. Methanobrevibacter acididurans isolated from slurry of an anaerobic digester running on alcohol distillery wastewater has been described earlier by this lab. This organism could grow optimally at pH 6.0. In the experiments reported herein, M. acididurans showed better methanogenesis under acidic conditions with high VFA, particularly acetate, than Methanobacterium bryantii, a common hydrogenotrophic inhabitant of anaerobic digesters. Addition of M. acididurans culture to digesting slurry of acidogenic as well as methanogenic digesters running on distillery wastewater showed increase in methane production and decrease in accumulation of volatile fatty acids. The results proved the feasibility of application of M. acididurans in anaerobic digesters.

Anaerobic Nitrogen Fixers on Mars

NASA Astrophysics Data System (ADS)

Lewis, B. G.

2000-07-01

The conversion of atmospheric nitrogen gas to the protein of living systems is an amazing process of nature. The first step in the process is biological nitrogen fixation, the transformation of N2 to NH3. The phenomenon is crucial for feeding the billions of our species on Earth. On Mars, the same process may allow us to discover how life can adapt to a hostile environment, and render it habitable. Hostile environments also exist on Earth. For example, nothing grows in coal refuse piles due to the oxidation of pyrite and marcasite to sulfuric acid. Yet, when the acidity is neutralized, alfalfa and soybean plants develop root nodules typical of symbiotic nitrogen fixation with Rhizobium species possibly living in the pyritic material. When split open, these nodules exhibited the pinkish color of leghemoglobin, a protein in the nodule protecting the active nitrogen-fixing enzyme nitrogenase against the toxic effects of oxygen. Although we have not yet obtained direct evidence of nitrogenase activity in these nodules (reduction of acetylene to ethylene, for example), these findings suggested the possibility that nitrogen fixation was taking place in this hostile, non-soil material. This immediately raises the possibility that freeliving anaerobic bacteria which fix atmospheric nitrogen on Earth, could do the same on Mars.

Fate of Trace Metals in Anaerobic Digestion.

PubMed

Fermoso, F G; van Hullebusch, E D; Guibaud, G; Collins, G; Svensson, B H; Carliell-Marquet, C; Vink, J P M; Esposito, G; Frunzo, L

2015-01-01

A challenging, and largely uncharted, area of research in the field of anaerobic digestion science and technology is in understanding the roles of trace metals in enabling biogas production. This is a major knowledge gap and a multifaceted problem involving metal chemistry; physical interactions of metal and solids; microbiology; and technology optimization. Moreover, the fate of trace metals, and the chemical speciation and transport of trace metals in environments--often agricultural lands receiving discharge waters from anaerobic digestion processes--simultaneously represents challenges for environmental protection and opportunities to close process loops in anaerobic digestion.

Bacterial metabolism of aromatic compounds and a complex hazardous waste under anaerobic conditions

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

O'Connor, O.A.

1992-01-01

The biological fate of organic chemicals in the environment depends upon a variety of physical/chemical factors. In the absence of molecular oxygen, the importance of terminal electron acceptors has been often overlooked. Since anaerobic microbial consortia are dependent upon the availability of particular electron acceptors, these conditions can play an important role in influencing the fate of environmental pollutants. In this research, different electron acceptors were evaluated for their effects on the biodegradation of environmental toxicants. Two anaerobic bioassays, the Biochemical Methane Potential (BMP) and the Anaerobic Toxicity Assay (ATA), were used to evaluate a series of phthalic acid estersmore » (PAEs), substituted phenols and a landfill leachate, for their methanogenic biodegradability and toxicity. Many of the PAEs and phenols could be stoichiometrically mineralized. In addition, the landfill leachate was found to be inhibitory at concentrations greater than 10%, and partially mineralized in approximately 50 weeks. Based upon these assays, 6 different functional groups and their isomers were evaluated for their effect on the biodegradability and toxicity of phenol under methanogenic and denitrifying conditions. These results indicated that nitro- and chloro-substituted phenols were persistent under denitrifying conditions. Under methanogenic conditions, these compounds were metabolized to a more reduced intermediate with less toxicity. Conversely, amino-substituted phenols were not readily mineralized under methanogenic conditions, but were metabolized after minimal lag under denitrifying conditions. From active denitrifying phenol degrading cultures, a pure culture was obtained which could grow on phenol and on a variety of other alkyl-substituted aromatic compounds. Additional studies have tentatively identified several alicyclic metabolites including cyclohexanol, 2-cyclohexene-1-ol, cyclohexanone and 2-cyclohexene-1-one from phenol

Effect of leachate recirculation on mesophilic anaerobic digestion of food waste.

PubMed

Shahriari, Haleh; Warith, Mostafa; Hamoda, Mohamed; Kennedy, Kevin J

2012-03-01

The effects of using untreated leachate for supplemental water addition and liquid recirculation on anaerobic digestion of food waste was evaluated by combining cyclic water recycle operations with batch mesophilic biochemical methane potential (BMP) assays. Cyclic BMP assays indicated that using an appropriate fraction of recycled leachate and fresh make up water can stimulate methanogenic activity and enhance biogas production. Conversely increasing the percentage of recycled leachate in the make up water eventually causes methanogenic inhibition and decrease in the rate of food waste stabilization. The decrease in activity is exacerbated as the number cycles increases. Inhibition is possibly attributed to accumulation and elevated concentrations of ammonia as well as other waste by products in the recycled leachate that inhibit methanogenesis. Copyright © 2011 Elsevier Ltd. All rights reserved.

Problematic effects of antibiotics on anaerobic treatment of swine wastewater.

PubMed

Cheng, D L; Ngo, H H; Guo, W S; Chang, S W; Nguyen, D D; Kumar, S Mathava; Du, B; Wei, Q; Wei, D

2018-05-04

Swine wastewaters with high levels of organic pollutants and antibiotics have become serious environmental concerns. Anaerobic technology is a feasible option for swine wastewater treatment due to its advantage in low costs and bioenergy production. However, antibiotics in swine wastewater have problematic effects on micro-organisms, and the stability and performance of anaerobic processes. Thus, this paper critically reviews impacts of antibiotics on pH, COD removal efficiencies, biogas and methane productions as well as the accumulation of volatile fatty acids (VFAs) in the anaerobic processes. Meanwhile, impacts on the structure of bacteria and methanogens in anaerobic processes are also discussed comprehensively. Furthermore, to better understand the effect of antibiotics on anaerobic processes, detailed information about antimicrobial mechanisms of antibiotics and microbial functions in anaerobic processes is also summarized. Future research on deeper knowledge of the effect of antibiotics on anaerobic processes are suggested to reduce their adverse environmental impacts. Copyright © 2018 Elsevier Ltd. All rights reserved.

Application of Anaerobic Digestion Model No. 1 for simulating anaerobic mesophilic sludge digestion

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

Mendes, Carlos, E-mail: carllosmendez@gmail.com; Esquerre, Karla, E-mail: karlaesquerre@ufba.br; Matos Queiroz, Luciano, E-mail: lmqueiroz@ufba.br

2015-01-15

Highlights: • The behavior of a anaerobic reactor was evaluated through modeling. • Parametric sensitivity analysis was used to select most sensitive of the ADM1. • The results indicate that the ADM1 was able to predict the experimental results. • Organic load rate above of 35 kg/m{sup 3} day affects the performance of the process. - Abstract: Improving anaerobic digestion of sewage sludge by monitoring common indicators such as volatile fatty acids (VFAs), gas composition and pH is a suitable solution for better sludge management. Modeling is an important tool to assess and to predict process performance. The present studymore » focuses on the application of the Anaerobic Digestion Model No. 1 (ADM1) to simulate the dynamic behavior of a reactor fed with sewage sludge under mesophilic conditions. Parametric sensitivity analysis is used to select the most sensitive ADM1 parameters for estimation using a numerical procedure while other parameters are applied without any modification to the original values presented in the ADM1 report. The results indicate that the ADM1 model after parameter estimation was able to predict the experimental results of effluent acetate, propionate, composites and biogas flows and pH with reasonable accuracy. The simulation of the effect of organic shock loading clearly showed that an organic shock loading rate above of 35 kg/m{sup 3} day affects the performance of the reactor. The results demonstrate that simulations can be helpful to support decisions on predicting the anaerobic digestion process of sewage sludge.« less

[Evaluation for anaerobic culture system: Anoxomat Mart II].

PubMed

Kikuchi, Yuji; Sasaki, Hiromi; Furuhata, Yukie; Tazawa, Yoko; Horiuchi, Hajime; Okada, Jun

2007-01-01

Anoxomat Mart II (Mart Microbiology BV, Lichtenvooorde, Netherlands, Central Scientific Commerce Inc., Tokyo, Japan) is an anaerobic jar apparatus which uses a vacuum pump in combination with catalyst as gas replacement procedure to remove all traces of oxygen. As we had a chance to use Anoxomat Mart II, we compared it with other two anaerobic culture methods; namely AnaeroPack anaero (Mitsubishi Gas Chemical Co., Tokyo, Japan) which employs anaerobic jar method, and Concept400 (RUSKINN TECHNOLOGY LTD, England; Central Scientific Commerce INc., Tokyo, Japan) which uses anaerobic chamber method. We used 10 different species of anaerobic bacteria obtained from ATCC. One strain each of 10 species was cultured and examined for measurement of the sensitibity of an anaerobic indicator, th number of bacteria after 48 hour culture, the diameter of colonies, and MIC value. As a result, the time to reach the anaerobic condition was around 30 minutes by the Mart II against around 60 minutes by the AnaeroPack anaero. There was no difference concerning the number of bacteria after 48 hour culture among three methods. But anaerobic bacteria cultured by Mart II tended to make bigger colonies compared to other two methods in the 5 strains out of 9, except for one strain in which the diameter of colonies could not be measured. On the other hand, the comparison of MIC value showed good correlation in 11 antibiotics out of 12 among three methods. The MIC value of 11 antibiotics fitted within 1-fold difference, and 2-fold difference was observed in only one antibiotic. Mart II is so small that it does cheep consumables. From these reasons, we concluded that Mart II can be one of the useful anerobic culture methods.

The role of anaerobic bacteria in the cystic fibrosis airway.

PubMed

Sherrard, Laura J; Bell, Scott C; Tunney, Michael M

2016-11-01

Anaerobic bacteria are not only normal commensals, but are also considered opportunistic pathogens and have been identified as persistent members of the lower airway community in people with cystic fibrosis of all ages and stages of disease. Currently, the role of anaerobic bacteria in cystic fibrosis lower airway disease is not well understood. Therefore, this review describes the recent studies relating to the potential pathophysiological role(s) of anaerobes within the cystic fibrosis lungs. The most frequently identified anaerobic bacteria in the lower airways are common to both cystic fibrosis and healthy lungs. Studies have shown that in cystic fibrosis, the relative abundance of anaerobes fluctuates in the lower airways with reduced lung function and increased inflammation associated with a decreased anaerobic load. However, anaerobes found within the lower airways also produce virulence factors, may cause a host inflammatory response and interact synergistically with recognized pathogens. Anaerobic bacteria are potentially members of the airway microbiota in health but could also contribute to the pathogenesis of lower airway disease in cystic fibrosis via both direct and indirect mechanisms. A personalized treatment strategy that maintains a normal microbial community may be possible in the future.

Modified Anaerobic Digestion Model No.1 for dry and semi-dry anaerobic digestion of solid organic waste.

PubMed

Liotta, Flavia; Chatellier, Patrice; Esposito, Giovanni; Fabbricino, Massimiliano; Frunzo, Luigi; van Hullebusch, Eric D; Lens, Piet N L; Pirozzi, Francesco

2015-01-01

The role of total solids (TS) content in anaerobic digestion of selected complex organic matter, e.g. rice straw and food waste, was investigated. A range of TS from wet (4.5%) to dry (23%) was evaluated. A modified version of the Anaerobic Digestion Model No.1 for a complex organic substrate is proposed to take into account the effect of the TS content on anaerobic digestion. A linear function that correlates the kinetic constants of three specific processes (i.e. disintegration, acetate and propionate up-take) was included in the model. Results of biomethanation and volatile fatty acids production tests were used to calibrate the proposed model. Model simulations showed a good agreement between numerical and observed data.

Antimicrobial susceptibility of anaerobic bacteria in New Zealand: 1999-2003.

PubMed

Roberts, Sally A; Shore, Keith P; Paviour, Susan D; Holland, David; Morris, Arthur J

2006-05-01

Routine susceptibility testing of all anaerobic organisms is not advocated, but it is useful for laboratories to test periodically for anaerobic organisms and provide local susceptibility data to guide therapy. This study reports the national trend of antibiotic susceptibility of clinically significant anaerobes in New Zealand. Clinical isolates were tested using standardized methods against a range of antibiotics commonly used to treat anaerobic infections. Susceptibility was determined using NCCLS criteria. The change in susceptibility trends between this study and earlier studies was measured by comparing the geometric mean of the MIC. A total of 364 anaerobes were tested. Penicillin had poor activity against Bacteroides spp., Prevotella spp., Eubacterium spp., Clostridium tertium and Veillonella spp. In general, Fusobacterium spp., Bacteroides ureolyticus, Propionibacterium spp., Clostridium perfringens and anaerobic streptococci isolates, with the exception of Peptostreptococcus anaerobius, were penicillin susceptible. Amoxicillin/clavulanate showed good activity against most anaerobes, but resistance was seen with Bacteroides fragilis group and P. anaerobius isolates. Cefoxitin was more active than cefotetan, particularly against non-B. fragilis species, Eubacterium spp. and P. anaerobius. Meropenem and imipenem showed good activity against all anaerobes, with only 2 and 4% of Bacteroides spp., respectively, showing resistance. With the exception of Propionibacterium acnes isolates, which are predictably resistant, metronidazole was active against all anaerobes tested. There has been little change in susceptibility since 1997. Metronidazole, cefoxitin, piperacillin/tazobactam and amoxicillin/clavulanate remain good empirical choices when anaerobes are expected in our setting. No clinically relevant changes in susceptibility over time were found.

Thermodynamic analysis of fermentation and anaerobic growth of baker's yeast for ethanol production.

PubMed

Teh, Kwee-Yan; Lutz, Andrew E

2010-05-17

Thermodynamic concepts have been used in the past to predict microbial growth yield. This may be the key consideration in many industrial biotechnology applications. It is not the case, however, in the context of ethanol fuel production. In this paper, we examine the thermodynamics of fermentation and concomitant growth of baker's yeast in continuous culture experiments under anaerobic, glucose-limited conditions, with emphasis on the yield and efficiency of bio-ethanol production. We find that anaerobic metabolism of yeast is very efficient; the process retains more than 90% of the maximum work that could be extracted from the growth medium supplied to the chemostat reactor. Yeast cells and other metabolic by-products are also formed, which reduces the glucose-to-ethanol conversion efficiency to less than 75%. Varying the specific ATP consumption rate, which is the fundamental parameter in this paper for modeling the energy demands of cell growth, shows the usual trade-off between ethanol production and biomass yield. The minimum ATP consumption rate required for synthesizing cell materials leads to biomass yield and Gibbs energy dissipation limits that are much more severe than those imposed by mass balance and thermodynamic equilibrium constraints. 2010 Elsevier B.V. All rights reserved.

Anaerobic Infections in Children with Neurological Impairments.

ERIC Educational Resources Information Center

Brook, Itzhak

1995-01-01

Children with neurological impairments are prone to develop serious infection with anaerobic bacteria. The most common anaerobic infections are decubitus ulcers; gastrostomy site wound infections; pulmonary infections (aspiration pneumonia, lung abscesses, and tracheitis); and chronic suppurative otitis media. The unique microbiology of each of…

Start-up and operation strategies on the liquefied food waste anaerobic digestion and a full-scale case application.

PubMed

Meng, Ying; Shen, Fei; Yuan, Hairong; Zou, Dexun; Liu, Yanping; Zhu, Baoning; Chufo, Akiber; Jaffar, Muhammad; Li, Xiujin

2014-11-01

Batch anaerobic digestion was employed to investigate the efficient start-up strategies for the liquefied food waste, and sequencing batch digestion was also performed to determine maximum influent organic loading rate (OLR) for efficient and stable operation. The results indicated that the start-up could be well improved using appropriate wastewater organic load and food-to-microorganism ratios (F/M). When digestion was initialized at low chemical oxygen demand (COD) concentration of 20.0 gCOD L(-1), the start-up would go well using lower F/M ratio of 0.5-0.7. The OLR 7.0 gCOD L(-1) day(-1) was recommended for operating the ASBR digestion, in which the COD conversion of 96.7 ± 0.53% and biomethane yield of 3.5 ± 0.2 L gCOD(-1) were achieved, respectively. The instability would occur when OLR was higher than 7.0 gCOD L(-1) day(-1), and this instability was not recoverable. Lipid was suggested to be removed before anaerobic digestion. The anaerobic digestion process in engineering project ran well, and good performance was achieved when the start-up and operational strategies from laboratory study were applied. For case application, stable digestion performance was achieved in a digester (850 m(3) volume) with biogas production of 1.0-3.8 m(3) m(-3) day(-1).

Comparative evaluation of anaerobic digestion for sewage sludge and various organic wastes with simple modeling.

PubMed

Hidaka, Taira; Wang, Feng; Tsumori, Jun

2015-09-01

Anaerobic co-digestion of sewage sludge and other organic wastes, such as kitchen garbage, food waste, and agricultural waste, at a wastewater treatment plant (WWTP) is a promising method for both energy and material recovery. Substrate characteristics and the anaerobic digestion performance of sewage sludge and various organic wastes were compared using experiments and modeling. Co-digestion improved the value of digested sewage sludge as a fertilizer. The relationship between total and soluble elemental concentrations was correlated with the periodic table: most Na and K (alkali metals) were soluble, and around 20-40% of Mg and around 10-20% of Ca (alkaline earth metals) were soluble. The ratio of biodegradable chemical oxygen demand of organic wastes was 65-90%. The methane conversion ratio and methane production rate under mesophilic conditions were evaluated using a simplified mathematical model. There was reasonably close agreement between the model simulations and the experimental results in terms of methane production and nitrogen concentration. These results provide valuable information and indicate that the model can be used as a pre-evaluation tool to facilitate the introduction of co-digestion at WWTPs. Copyright © 2015 Elsevier Ltd. All rights reserved.

Mitigation of Humic Acid Inhibition in Anaerobic Digestion of Cellulose by Addition of Various Salts.

PubMed

Azman, Samet; Khadem, Ahmad F; Zeeman, Grietje; van Lier, Jules B; Plugge, Caroline M

2015-03-25

Humic compounds are inhibitory to the anaerobic hydrolysis of cellulosic biomass. In this study, the impact of salt addition to mitigate the inhibitory effects of humic compounds was investigated. The experiment was conducted using batch tests to monitor the anaerobic hydrolysis of cellulose in the presence of humic acid. Sodium, potassium, calcium, magnesium and iron salts were tested separately for their efficiency to mitigate humic acid inhibition. All experiments were done under mesophilic conditions (30 °C) and at pH 7. Methane production was monitored online, using the Automatic Methane Potential Test System. Methane production, soluble chemical oxygen demand and volatile fatty acid content of the samples were measured to calculate the hydrolysis efficiencies. Addition of magnesium, calcium and iron salts clearly mitigated the inhibitory effects of humic acid and hydrolysis efficiencies reached up to 75%, 65% and 72%, respectively, which were similar to control experiments. Conversely, potassium and sodium salts addition did not mitigate the inhibition and hydrolysis efficiencies were found to be less than 40%. Mitigation of humic acid inhibition via salt addition was also validated by inductively coupled plasma atomic emission spectroscopy analyses, which showed the binding capacity of different cations to humic acid.

Anaerobic digestion of microalgal bacterial flocs from a raceway pond treating aquaculture wastewater: need for a biorefinery.

PubMed

Van Den Hende, Sofie; Laurent, Cedric; Bégué, Marine

2015-11-01

An outdoor raceway pond with microalgal bacterial flocs (MaB-flocs) is a novel sunlight-based system to treat pikeperch aquaculture wastewater while producing biomass. The harvested MaB-floc biomass (33tonTSha(-1)y(-1)) needs further valorization. Therefore, the biochemical methane yield (BMY) of MaB-floc biomass was determined in batch experiments. The results show significant differences between the BMY of MaB-flocs amongst their harvest dates (128-226NLCH4kg(-1)VS), a low anaerobic digestion conversion efficiency (25.0-36.2%), a moderate chlorophyll a removal (51.5-86.9%) and a low biogas profit (<0.01€m(-3)wastewater). None of the pretreatment methods screened (freezing, thermal, microwave, ultrasonic and chlorination, flue gas sparging, and acid) can be recommended due to a low BMY improvement and/or unfavorable energy balance. Therefore, anaerobic digestion of this MaB-floc biomass should only be granted a supporting role within a biorefinery concept. Copyright © 2015 Elsevier Ltd. All rights reserved.

Synergistic effect of co-digestion to enhance anaerobic degradation of catering waste and orange peel for biogas production.

PubMed

Anjum, Muzammil; Khalid, Azeem; Qadeer, Samia; Miandad, Rashid

2017-09-01

Catering waste and orange peel were co-digested using an anaerobic digestion process. Orange peel is difficult to degrade anaerobically due to the presence of antimicrobial agents such as limonene. The present study aimed to examine the feasibility of anaerobic co-digestion of catering waste with orange peel to provide the optimum nutrient balance with reduced inhibitory effects of orange peel. Batch experiments were conducted using catering waste as a potential substrate mixed in varying ratios (20-50%) with orange peel. Similar ratios were followed using green vegetable waste as co-substrate. The results showed that the highest organic matter degradation (49%) was achieved with co-digestion of catering waste and orange peel at a 50% mixing ratio (CF4). Similarly, the soluble chemical oxygen demand (sCOD) was increased by 51% and reached its maximum value (9040 mg l -1 ) due to conversion of organic matter from insoluble to soluble form. Biogas production was increased by 1.5 times in CF4 where accumulative biogas was 89.61 m 3 t -1 substrate compared with 57.35 m 3 t -1 substrate in the control after 80 days. The main reason behind the improved biogas production and degradation is the dilution of inhibitory factors (limonene), with subsequent provision of balanced nutrients in the co-digestion system. The tCOD of the final digestate was decreased by 79.9% in CF4, which was quite high as compared with 68.3% for the control. Overall, this study revealed that orange peel waste is a highly feasible co-substrate for anaerobic digestion with catering waste for enhanced biogas production.

Food waste-to-energy conversion technologies: current status and future directions.

PubMed

Pham, Thi Phuong Thuy; Kaushik, Rajni; Parshetti, Ganesh K; Mahmood, Russell; Balasubramanian, Rajasekhar

2015-04-01

Food waste represents a significantly fraction of municipal solid waste. Proper management and recycling of huge volumes of food waste are required to reduce its environmental burdens and to minimize risks to human health. Food waste is indeed an untapped resource with great potential for energy production. Utilization of food waste for energy conversion currently represents a challenge due to various reasons. These include its inherent heterogeneously variable compositions, high moisture contents and low calorific value, which constitute an impediment for the development of robust, large scale, and efficient industrial processes. Although a considerable amount of research has been carried out on the conversion of food waste to renewable energy, there is a lack of comprehensive and systematic reviews of the published literature. The present review synthesizes the current knowledge available in the use of technologies for food-waste-to-energy conversion involving biological (e.g. anaerobic digestion and fermentation), thermal and thermochemical technologies (e.g. incineration, pyrolysis, gasification and hydrothermal oxidation). The competitive advantages of these technologies as well as the challenges associated with them are discussed. In addition, the future directions for more effective utilization of food waste for renewable energy generation are suggested from an interdisciplinary perspective. Copyright © 2014 Elsevier Ltd. All rights reserved.

Perspectives on anaerobic treatment in developing countries.

PubMed

Foresti, E

2001-01-01

Developing countries occupy regions where the climate is warm most of the time. Even in sub-tropical areas, low temperatures do not persist for long periods. This is the main factor that makes the use of anaerobic technology applicable and less expensive, even for the treatment of low-strength industrial wastewaters and domestic sewage. Based mainly on papers presented at the "VI Latin-American Workshop and Seminar on Anaerobic Digestion" held in Recife, Brazil, in November 2000, this text approaches the perspectives of anaerobic treatment of wastewaters in developing countries. Emphasis is given to domestic sewage treatment and to the use of compact systems in which sequential batch reactors (SBR) or dissolvedair flotation (DAF) systems are applied for the post-treatment of anaerobic reactor effluents. Experiments on bench- and pilot-plants have indicated that these systems can achieve high performance in removing organic matter and nutrients during the treatment of domestic sewage at ambient temperatures.

Maximal anaerobic power in Indian national hockey players.

PubMed Central

Bhanot, J. L.; Sidhu, L. S.

1983-01-01

Anaerobic power in relation to field position of 90 Indian hockey players has been studied. These players included 10 goalkeepers, 16 backs, 20 half-backs and 44 forwards. The goalkeepers possess maximum and forwards possess minimum anaerobic power while in vertical velocity, the former are the fastest and the latter are the slowest. In body weight the backs are heaviest followed by half-backs, goalkeepers and forwards. Among backs, the lefts are heavier, faster and have more anaerobic power than rights. In half-line players, the centre-half-backs are followed by left-half-backs and right-half-backs both in body weight and anaerobic power, while in vertical velocity, the left-half-backs are the fastest and centre-half-backs are the slowest. Among forwards, the centre-forwards are heaviest with maximum anaerobic power and are followed by inside-forwards and outside-forwards, whereas, in vertical velocity the inside-forwards are fastest followed by centre-forwards and outside-forwards. Images p34-a p34-b PMID:6850203

Anaerobic Transformation of Furfural by Methanococcus deltae (Delta)LH

PubMed Central

Belay, N.; Boopathy, R.; Voskuilen, G.

1997-01-01

Methanococcus deltae (Delta)LH was grown on H(inf2)-CO(inf2) in the presence of various concentrations of furfural. Furfural at higher concentrations, namely, 20 and 25 mM, inhibited growth of this organism. At concentration of 5 and 10 mM, no inhibition of growth was observed. The other methanogens in this study were not inhibited by 10 mM furfural. Among the methanogens tested, M. deltae was capable of transforming furfural, whereas Methanobacterium thermoautotrophicum Marburg, Methanosarcina barkeri 227, Methanococcus thermolithotrophicus, and Methanobrevibacter ruminantium lacked this capability. One hundred percent removal of furfural was observed within 48 h of incubation in M. deltae cultures. The end product observed during furfural metabolism was furfuryl alcohol. An almost stoichiometric amount of furfuryl alcohol was produced by M. deltae. This transformation is likely to be of value in the detoxification of furfural and in its ultimate conversion to methane and CO(inf2) by anaerobic digestion. PMID:16535618

Anaerobic Benzene Oxidation by Geobacter Species

PubMed Central

Bain, Timothy S.; Nevin, Kelly P.; Barlett, Melissa A.; Lovley, Derek R.

2012-01-01

The abundance of Geobacter species in contaminated aquifers in which benzene is anaerobically degraded has led to the suggestion that some Geobacter species might be capable of anaerobic benzene degradation, but this has never been documented. A strain of Geobacter, designated strain Ben, was isolated from sediments from the Fe(III)-reducing zone of a petroleum-contaminated aquifer in which there was significant capacity for anaerobic benzene oxidation. Strain Ben grew in a medium with benzene as the sole electron donor and Fe(III) oxide as the sole electron acceptor. Furthermore, additional evaluation of Geobacter metallireducens demonstrated that it could also grow in benzene-Fe(III) medium. In both strain Ben and G. metallireducens the stoichiometry of benzene metabolism and Fe(III) reduction was consistent with the oxidation of benzene to carbon dioxide with Fe(III) serving as the sole electron acceptor. With benzene as the electron donor, and Fe(III) oxide (strain Ben) or Fe(III) citrate (G. metallireducens) as the electron acceptor, the cell yields of strain Ben and G. metallireducens were 3.2 × 109 and 8.4 × 109 cells/mmol of Fe(III) reduced, respectively. Strain Ben also oxidized benzene with anthraquinone-2,6-disulfonate (AQDS) as the sole electron acceptor with cell yields of 5.9 × 109 cells/mmol of AQDS reduced. Strain Ben serves as model organism for the study of anaerobic benzene metabolism in petroleum-contaminated aquifers, and G. metallireducens is the first anaerobic benzene-degrading organism that can be genetically manipulated. PMID:23001648

Effect of hydrothermal pre-treatment (HTP) on poultry slaughterhouse waste (PSW) sludge for the enhancement of the solubilization, physical properties, and biogas production through anaerobic digestion.

PubMed

Park, Seyong; Yoon, Young-Man; Han, Seong Kuk; Kim, Daegi; Kim, Ho

2017-06-01

This study is an assessment of the hydrothermal pre-treatment (HTP) of poultry slaughterhouse waste (PSW) sludge for the enhancement of the solubilization, physical properties, and biogas production through anaerobic digestion. This assessment was carried out to ascertain the optimal HTP temperature. The solubilization and physical properties efficacy was investigated by capillary suction time (CST), time to filter (TTF), and particle size. In addition, the anaerobic digestion was investigated through biochemical methane potential (BMP) tests and subsequent statistical analysis using the modified Gompertz model. HTP was found to have improved the solubilization of the PSW sludge with increasing HTP temperature. In addition, the results of the CST, TTF, and particle size decreased with increasing HTP temperature. These results of the assessment that was conducted in this study confirm that the HTP process indeed modifies the physical properties of PSWs to enhance the solubilization of organic solids. Nevertheless, the results of the BMP tests and the modified Gompertz model analysis show that the optimal HTP temperature of PSWs for anaerobic digestion is 190°C. These findings show that to achieve high conversion efficiency, an accurately designed pre-treatment step must be included in the overall anaerobic digestion process for wastewater treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

Upflow anaerobic sludge blanket reactor--a review.

PubMed

Bal, A S; Dhagat, N N

2001-04-01

Biological treatment of wastewater basically reduces the pollutant concentration through microbial coagulation and removal of non-settleable organic colloidal solids. Organic matter is biologically stabilized so that no further oxygen demand is exerted by it. The biological treatment requires contact of the biomass with the substrate. Various advances and improvements in anaerobic reactors to achieve variations in contact time and method of contact have resulted in development of in suspended growth systems, attached growth or fixed film systems or combinations thereof. Although anaerobic systems for waste treatment have been used since late 19th century, they were considered to have limited treatment efficiencies and were too slow to serve the needs of a quickly expanding wastewater volume, especially in industrialized and densely populated areas. At present aerobic treatment is the most commonly used process to reduce the organic pollution level of both domestic and industrial wastewaters. Aerobic techniques, such as activated sludge process, trickling filters, oxidation ponds and aerated lagoons, with more or less intense mixing devices, have been successfully installed for domestic wastewater as well as industrial wastewater treatment. Anaerobic digestion systems have undergone modifications in the last two decades, mainly as a result of the energy crisis. Major developments have been made with regard to anaerobic metabolism, physiological interactions among different microbial species, effects of toxic compounds and biomass accumulation. Recent developments however, have demonstrated that anaerobic processes might be an economically attractive alternative for the treatment of different types of industrial wastewaters and in (semi-) tropical areas also for domestic wastewaters. The anaerobic degradation of complex, particulate organic matter has been described as a multistep process of series and parallel reactions. It involves the decomposition of organic and

Factor Analysis of Various Anaerobic Power Tests.

ERIC Educational Resources Information Center

Manning, James M.; And Others

A study investigated the relationship between selected anthropometric variables and of numerous anaerobic power tests with measures obtained on an isokinetic dynamometer. Thirty-one male college students performed several anaerobic power tests, including: the vertical jump using the Lewis formula; the Margaria-Kalamen stair climb test; the Wingate…

In situ bioremediation of petroleum hydrocarbons and chlorinated hydrocarbons: Three case studies

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

Bost, R.C.; Perry, R.G.; Barber, T.

1997-06-01

In situ biodegradation of organic contaminants is one of the most cost-effective means of site remediation. This method has proven successful in soils, ground water, and slurries. Bacteria capable of degrading organic contaminants within an aquifer include many species from a wide spectrum of genera, e.g. Pseudomonas, Corynebacterium, Bacillus, etc. In most cases, a mixture of bacterial strains is required to completely oxidize a complex organic contaminant. Each strain of an organism may target a specific compound, working together with other organisms to ultimately degrade each intermediate until complete degradation, also known as mineralization, occurs. One or more of themore » following mechanisms are utilized by bacteria for organic chemical degradation: (1) aerobic, (2) anaerobic, and (3) co-metabolic. During aerobic oxidation of organic chemicals, bacteria utilize the pollutant as an electron and hydrogen source and oxygen acts as the electron and hydrogen acceptor, resulting in water. As the bacterial enzymes cleave the compound, oxidized products are produced along with energy for the reaction to proceed. This is the most rapid and widely utilized mechanism. Dehalogenation occurs under aerobic, or perhaps more often, under anoxic conditions. This process occurs in the presence of alternate electron acceptors and replaces chlorine with hydrogen. The mechanism of co-metabolism can be aerobic or anaerobic, but is more often aerobic. This process requires a separate energy source for the bacterial cell because the pollutant is not utilized as an energy source. The role of bioremediation in site remediation is demonstrated below by three case studies: (1) a refinery, (2) a municipal landfill and (3) a pesticide formulation plant.« less

A Single-Culture Bioprocess of Methanothermobacter thermautotrophicus to Upgrade Digester Biogas by CO2-to-CH4 Conversion with H2

PubMed Central

Martin, Matthew R.; Fornero, Jeffrey J.; Angenent, Largus T.

2013-01-01

We optimized and tested a postbioprocessing step with a single-culture archaeon to upgrade biogas (i.e., increase methane content) from anaerobic digesters via conversion of CO2 into CH4 by feeding H2 gas. We optimized a culture of the thermophilic methanogen Methanothermobacter thermautotrophicus using: (1) a synthetic H2/CO2 mixture; (2) the same mixture with pressurization; (3) a synthetic biogas with different CH4 contents and H2; and (4) an industrial, untreated biogas and H2. A laboratory culture with a robust growth (dry weight of 6.4–7.4 g/L; OD600 of 13.6–15.4), a volumetric methane production rate of 21 L/L culture-day, and a H2 conversion efficiency of 89% was moved to an industrial anaerobic digester facility, where it was restarted and fed untreated biogas with a methane content of ~70% at a rate such that CO2 was in excess of the stoichiometric requirements in relation to H2. Over an 8-day operating period, the dry weight of the culture initially decreased slightly before stabilizing at an elevated level of ~8 g/L to achieve a volumetric methane production rate of 21 L/L culture-day and a H2 conversion efficiency of 62%. While some microbial contamination of the culture was observed via microscopy, it did not affect the methane production rate of the culture. PMID:24194675

Anaerobic Metabolism in the N-Limited Green Alga Selenastrum minutum: II. Assimilation of Ammonium by Anaerobic Cells.

PubMed

Vanlerberghe, G C; Turpin, D H

1990-11-01

The green alga Selenastrum minutum (Naeg.) Collins is able to assimilate NH(4) (+) in the dark under anaerobic conditions (GC Vanlerberghe, AK Horsey, HG Weger, DH Turpin [1989] Plant Physiol 91: 1551-1557). In the present study, analysis of metabolites following addition of NH(4) (+) to cells acclimated to anaerobic conditions has shown the following. There was a transient decline in adenylate energy charge from 0.6 to 0.4 followed by a recovery back to ~0.6. This was accompanied by a rapid increase in pyruvate/phosphoenolpyruvate and fructose-1,6-bisphosphate/fructose-6-phosphate ratios indicating activation of pyruvate kinase and 6-phosphofructokinase, respectively. There was also an increase in fructose-2,6-bisphosphate, which, since this alga lacks pyrophosphate dependent 6-phosphofructokinase can be inferred to inhibit gluconeogenic fructose-1,6-bisphosphatase. These changes resulted in an increase in the rate of anaerobic starch breakdown. Anaerobic NH(4) (+) assimilation also resulted in a two-fold increase in the rate of production of the major fermentative end-products in this alga, d-lactate and ethanol. There was no change in the rate of accumulation of the fermentative end product succinate but malate accumulated under anoxia during NH(4) (+) assimilation. A rapid increase in Gln and decline in Glu indicates that primary NH(4) (+) assimilation under anoxia was via glutamine synthetase-glutamate synthase. Almost all N assimilated under these conditions was sequestered in alanine. These results allow us to propose a model for the regulation of carbon metabolism during anaerobic NH(4) (+) assimilation.

Combined anaerobic and aerobic digestion for increased solids reduction and nitrogen removal.

PubMed

Novak, John T; Banjade, Sarita; Murthy, Sudhir N

2011-01-01

A unique sludge digestion system consisting of anaerobic digestion followed by aerobic digestion and then a recycle step where thickened sludge from the aerobic digester was recirculated back to the anaerobic unit was studied to determine the impact on volatile solids (VS) reduction and nitrogen removal. It was found that the combined anaerobic/aerobic/anaerobic (ANA/AER/ANA) system provided 70% VS reduction compared to 50% for conventional mesophilic anaerobic digestion with a 20 day SRT and 62% for combined anaerobic/aerobic (ANA/AER) digestion with a 15 day anaerobic and a 5 day aerobic SRT. Total Kjeldahl nitrogen (TKN) removal for the ANA/AER/ANA system was 70% for sludge wasted from the aerobic unit and 43.7% when wasted from the anaerobic unit. TKN removal was 64.5% for the ANA/AER system. Copyright © 2010 Elsevier Ltd. All rights reserved.

Anaerobic codigestion of dairy manure and food manufacturing waste for renewable energy generation in New York State

NASA Astrophysics Data System (ADS)

Rankin, Matthew J.

Anaerobic digestion is a microbiological process that converts biodegradable organic material into biogas, consisting primarily of methane and carbon dioxide. Anaerobic digestion technologies have been integrated into wastewater treatment facilities nationwide for many decades to increase the economic viability of the treatment process by converting a waste stream into two valuable products: biogas and fertilizer. Thus, anaerobic digestion offers potential economic and environmental benefits of organic waste diversion and renewable energy generation. The use of biogas has many applications, including cogeneration, direct combustion, upgrading for conversion to feed a fuel cell, and compression for injection into the natural gas grid or for vehicular use. The potential benefits of waste diversion and renewable energy generation are now being realized by major organic waste generators in New York State, in particular the food manufacturing and dairy industries, thus warranting an analysis of the energy generation potential for these waste products. Anaerobic codigestion of dairy manure and food-based feedstocks reflects a cradle-to- cradle approach to organic waste management. Given both of their abundance throughout New York State, waste-to-energy processes represent promising waste management strategies. The objective of this thesis was to evaluate the current technical and economic feasibility of anaerobically codigesting existing dairy manure and food manufacturing waste feedstocks in New York State to produce high quality biogas for renewable energy generation. The first element to determining the technical feasibility of anaerobic codigestion potential in New York State was to first understand the feedstock availability. A comprehensive survey of existing organic waste streams was conducted. The key objective was to identify the volume and composition of dairy manure and liquid-phase food manufacturing waste streams available in New York State to make

Microbial Anaerobic Digestion (Bio-Digesters) as an Approach to the Decontamination of Animal Wastes in Pollution Control and the Generation of Renewable Energy

PubMed Central

Manyi-Loh, Christy E.; Mamphweli, Sampson N.; Meyer, Edson L.; Okoh, Anthony I.; Makaka, Golden; Simon, Michael

2013-01-01

With an ever increasing population rate; a vast array of biomass wastes rich in organic and inorganic nutrients as well as pathogenic microorganisms will result from the diversified human, industrial and agricultural activities. Anaerobic digestion is applauded as one of the best ways to properly handle and manage these wastes. Animal wastes have been recognized as suitable substrates for anaerobic digestion process, a natural biological process in which complex organic materials are broken down into simpler molecules in the absence of oxygen by the concerted activities of four sets of metabolically linked microorganisms. This process occurs in an airtight chamber (biodigester) via four stages represented by hydrolytic, acidogenic, acetogenic and methanogenic microorganisms. The microbial population and structure can be identified by the combined use of culture-based, microscopic and molecular techniques. Overall, the process is affected by bio-digester design, operational factors and manure characteristics. The purpose of anaerobic digestion is the production of a renewable energy source (biogas) and an odor free nutrient-rich fertilizer. Conversely, if animal wastes are accidentally found in the environment, it can cause a drastic chain of environmental and public health complications. PMID:24048207

Microbial anaerobic digestion (bio-digesters) as an approach to the decontamination of animal wastes in pollution control and the generation of renewable energy.

PubMed

Manyi-Loh, Christy E; Mamphweli, Sampson N; Meyer, Edson L; Okoh, Anthony I; Makaka, Golden; Simon, Michael

2013-09-17

With an ever increasing population rate; a vast array of biomass wastes rich in organic and inorganic nutrients as well as pathogenic microorganisms will result from the diversified human, industrial and agricultural activities. Anaerobic digestion is applauded as one of the best ways to properly handle and manage these wastes. Animal wastes have been recognized as suitable substrates for anaerobic digestion process, a natural biological process in which complex organic materials are broken down into simpler molecules in the absence of oxygen by the concerted activities of four sets of metabolically linked microorganisms. This process occurs in an airtight chamber (biodigester) via four stages represented by hydrolytic, acidogenic, acetogenic and methanogenic microorganisms. The microbial population and structure can be identified by the combined use of culture-based, microscopic and molecular techniques. Overall, the process is affected by bio-digester design, operational factors and manure characteristics. The purpose of anaerobic digestion is the production of a renewable energy source (biogas) and an odor free nutrient-rich fertilizer. Conversely, if animal wastes are accidentally found in the environment, it can cause a drastic chain of environmental and public health complications.

Influence of upper-body external loading on anaerobic exercise performance.

PubMed

Inacio, Mario; Dipietro, Loretta; Visek, Amanda J; Miller, Todd A

2011-04-01

The purpose of this study was to assess the threshold where simulated adipose tissue weight gain significantly affects performance in common anaerobic tasks and determine whether differences exist between men and women. Forty-six subjects (men = 21; women = 25) were tested for vertical jump, 20- and 40-yd dash, and 20-yd shuttle tests under 6 different loading conditions (0, 2, 4, 6, 8, and 10% of added body weight). Results were compared to each subject's baseline values (0% loading condition). Results demonstrate significant decrements in performance, starting at the 2% loading condition, for both genders, in every performance test (p < 0.05). On average, subjects jumped 4.91 ± 0.29 to 9.83 ± 0.30 cm less, increased agility test times from 5.49 ± 0.56 to 5.86 ± 0.61 seconds, and increased sprint times from 7.80 ± 0.96 to 8.39 ± 1.07 seconds (2-10%, respectively; p < 0.05). When lower-body power was corrected for total body mass, men exerted significantly more power than women did in every loading condition. Conversely, when lower-body power was corrected for lean body mass, men exerted significantly more power than did women only at the 2% loading condition. This study demonstrates that for the specific anaerobic performance tests performed, increases in external loading as low as 2% of body weight results in significant decreases in performance. Moreover, for these specific tests, men and women tend to express the same threshold in performance decrements.

ANAEROBIC AND AEROBIC TREATMENT OF CHLORINATED ALIPHATIC COMPOUNDS

EPA Science Inventory

Biological degradation of 12 chlorinated aliphatic compounds (CACs) was assessed in bench-top reactors and in serum bottle tests. Three continuously mixed daily batch-fed reactor systems were evaluated: anaerobic, aerobic, and sequential-anaerobic-aerobic (sequential). Glucose,...

Anaerobic digestion of palm oil mill effluent (POME) using bio-methane potential (BMP) test

NASA Astrophysics Data System (ADS)

Aziz, Nur Izzah Hamna A.; Hanafiah, Marlia M.

2018-04-01

Biogas is a promising sustainable and renewable energy alternative to reduce the dependence on fossil fuel. In Malaysia, the conversion of palm oil mill effluent (POME) to bioenergy has recently been expanded due to its high potential in generating energy. However, without a proper treatment and management, POME could be harmful to environment because it emits greenhouse gas emissions into the atmosphere and could also pollutes the watercourses if discharge directly due to the high acidity and chemical oxygen demand (COD) content. Many initiatives have been taken by the government towards sustainable development. Therefore, more efforts need to be practiced to improve and upscale the technology for a better waste management. In this study, the anaerobic digestion of POME was carried out using Bio-methane potential (BMP) test in batch and laboratory scales. Physicochemical characteristics and the biogas production of POME were measured. The BMP test under mesophilic condition was conducted for 23 consecutive days to measure the biogas production. The POME produced 721.3 cm3 of biogas by using anaerobic sludge as inoculum. The results also found that the methane (CH4) and carbon dioxide (CO2) gases produced with 360.65 cm3 and 288.52 cm3, respectively.

Peritoneal dialysis peritonitis by anaerobic pathogens: a retrospective case series

PubMed Central

2013-01-01

Background Bacterial infections account for most peritoneal dialysis (PD)-associated peritonitis episodes. However, anaerobic PD peritonitis is extremely rare and intuitively associated with intra-abdominal lesions. In this study, we examined the clinical characteristics of PD patients who developed anaerobic peritonitis. Methods We retrospectively identified all anaerobic PD peritonitis episodes from a prospectively collected PD registry at a single center between 1990 and 2010. Only patients receiving more than 3 months of PD were enrolled. We analyzed clinical features as well as outcomes of anaerobic PD peritonitis patients. Results Among 6 patients, 10 episodes of PD-associated peritonitis were caused by anaerobic pathogens (1.59% of all peritonitis episodes during study the period), in which the cultures from 5 episodes had mixed growth. Bacteroides fragilis was the most common species identified (4 isolates). Only 3 episodes were associated with gastrointestinal lesions, and 4 episodes were related to a break in sterility during exchange procedures. All anaerobic pathogens were susceptible to clindamycin and metronidazole, but penicillin resistance was noted in 4 isolates. Ampicillin/sulbactam resistance was found in 2 isolates. In 5 episodes, a primary response was achieved using the first-generation cephalosporin and ceftazidime or aminoglycoside. In 3 episodes, the first-generation cephalosporin was replaced with aminoglycosides. Tenckhoff catheter removal was necessary in 2 episodes. Only one episode ended with mortality (due to a perforated bowel). Conclusion Anaerobic PD-associated peritonitis might be predominantly caused by contamination, rather than intra-abdominal events. Half of anaerobic PD-associated peritonitis episodes had polymicrobial growth. The overall outcome of anaerobic peritonitis is fair, with a high catheter survival rate. PMID:23705895

Dry anaerobic digestion of food waste and cardboard at different substrate loads, solid contents and co-digestion proportions.

PubMed

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

2017-06-01

The increasing food waste production calls for developing efficient technologies for its treatment. Anaerobic processes provide an effective waste valorization. The influence of the initial substrate load on the performance of batch dry anaerobic co-digestion reactors treating food waste and cardboard was investigated. The load was varied by modifying the substrate to inoculum ratio (S/X), the total solids content and the co-digestion proportions. The results showed that the S/X was a crucial parameter. Within the tested values (0.25, 1 and 4gVS·gVS -1 ), only the reactors working at 0.25 produced methane. Methanosarcina was the main archaea, indicating its importance for efficient methanogenesis. Acidogenic fermentation was predominant at higher S/X, producing hydrogen and other metabolites. Higher substrate conversions (≤48%) and hydrogen yields (≤62mL·gVS -1 ) were achieved at low loads. This study suggests that different value-added compounds can be produced in dry conditions, with the initial substrate load as easy-to-control operational parameter. Copyright © 2017 Elsevier Ltd. All rights reserved.

Energy conversion of animal manures: Feasibility analysis for thirteen western states

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

Whittier, J.; Haase, S.; Milward, R.

1993-12-31

The growth and concentration of the livestock industry has led to environmental disposal problems for large quantities of manure at feedlots, dairies, poultry production plants, animal holding areas and pasturelands. Consequently, waste management systems that facilitate energy recovery are becoming increasingly attractive since they address pollution problems and allow for energy generation from manure resources. This paper presents a manure resource assessment for the 13 US Department of Energy, Western Regional Biomass Energy Program states, describes and evaluates available energy conversion technologies, identifies environmental and regulatory factors associated with manure collection, storage and disposal, and identifies common disposal practices specificmore » to animal types and areas within the WRBEP region. The paper also presents a pro forma economic analysis for selected manure-to-energy conversion technologies. The annual energy potential of various manures within the WRBEP region is equivalent to approximately 111 {times} 10{sup 13} Btu. Anaerobic digestion systems, both lagoon and plug flow, offer positive economic returns in a broad range of utility service territories.« less

Validity and reliability of the Hawaii anaerobic run test.

PubMed

Kimura, Iris F; Stickley, Christopher D; Lentz, Melissa A; Wages, Jennifer J; Yanagi, Kazuhiko; Hetzler, Ronald K

2014-05-01

This study examined the reliability and validity of the Hawaii anaerobic run test (HART) by comparing anaerobic capacity measures obtained to those during the Wingate Anaerobic Test (WAnT). Ninety-six healthy physically active volunteers (age, 22.0 ± 2.8 years; height, 163.9 ± 9.5 cm; body mass, 70.6 ± 14.7 kg; body fat %, 19.29 ± 5.39%) participated in this study. Each participant performed 2 anaerobic capacity tests: the WAnT and the HART by random assignment on separate days. The reliability of the HART was calculated from 2 separate trials of the test and then determined through intraclass correlation coefficients (ICCs). Blood samples were collected, and lactate was analyzed both pretest and posttest for each of the 2 exercise modes. Heart rate and rate of perceived exertion were also measured pre- and post-exercise. Hawaii anaerobic run test peak and mean momentum were calculated as body mass times highest or average split velocity, respectively. Intraclass correlation coefficients between trials of the HART for peak and mean momentum were 0.98 and 0.99, respectively (SEM = 18.8 and 25.7, respectively). Validity of the HART was established through comparison of momentum on the HART with power on the WAnT. High correlations were found between peak power and peak momentum (r = 0.88), as well as mean power and mean momentum (r = 0.94). The HART was considered to be a reliable test of anaerobic power. The HART was also determined to be a valid test of anaerobic power when compared with the WAnT. When testing healthy college-aged individuals, the HART offers an easy and inexpensive alternative maximal effort anaerobic power test to other established tests.

ANAEROBIC SOIL DISINFESTATION IN MICROCOSMS OF TWO SANDY SOILS.

PubMed

Stremińska, M A; Runia, W T; Termorshuizen, A J; Feil, H; Van Der Wurff, A W G

2014-01-01

In recent years, anaerobic soil disinfestation (ASD) has been proposed as an alternative control method of soil-borne plant pathogens. It involves adding a labile carbon source, irrigating the soil to stimulate decomposition of organic material and then covering the soil with air-tight plastic to limit gas exchange. During the ASD process, soil microorganisms switch from aerobic to anaerobic metabolism. As a result, by-products of anaerobic metabolism are released into the soil environment such as various organic acids and gases. These by-products are reported to have a negative effect on survival of soil-borne plant pathogens. However, the efficacy of ASD to reduce soil-borne pathogens in practice may vary significantly. Therefore, we studied the efficacy of the ASD process in two different soils. In addition, it was investigated whether a pre-treatment with an anaerobic bacterial inoculum prior to ASD affected the efficacy of the process. Two sandy soils (dune sand and glacial sand) were inoculated in 2 L soil microcosms. We tested the efficacy of ASD treatment against the potato cyst nematode Globodera pallida. For each soil, three treatments were used: control treatment (no Herbie addition, aerobic incubation), ASD 1 (organic substrate addition, anaerobic incubation) and ASD 2 (organic substrate and anaerobic bacterial inoculum addition, anaerobic incubation). Soil microcosms were incubated in the dark at 20°C for two weeks. We observed that anaerobic soil disinfestation treatments were highly effective against Potato Cyst Nematode (PCN), with pathogen being eradicated totally in all but one ASD treatment (glacial sand ASD2) within two weeks. The relative abundance of Firmicutes (spore-forming bacteria, often fermentative) in total bacteria increased significantly in ASD treated soils. Numbers of these bacteria correlated positively with increased concentrations of acetic and butyric acids in soil water phase in ASD treatments.

Assessment of anaerobic blood cultures in pediatric oncology patients.

PubMed

Monsonís Cabedo, Manuel; Rives Solá, Susana; Noguera-Julian, Antoni; Urrea Ayala, Mireia; Cruz Martinez, Ofelia; Gené Giralt, Amadeu

2017-01-01

The routine use of a single aerobic bottle for blood culture in pediatric patients has become commonplace, as anaerobic bacteria are not frequently involved in clinically significant infections. The aim of this study was to assess the usefulness of routinely performing anaerobic blood cultures in pediatric oncology patients. Prospective study was conducted on pediatric (<18 years) patients affected with febrile syndrome after receiving chemotherapy for hematological or solid malignancies. Samples were inoculated into pediatric aerobic and standard anaerobic bottles (BacT/Alert automatic system). Strains were considered clinically significant, or deemed as contaminants, depending on isolation circumstances and clinical criteria. A total of 876 blood cultures from 228 patients were processed during the 21-month study period (January 2014 to September 2015). Baseline diagnosis included 143 solid tumors and 67/18 cases of leukemia/lymphoma. Bacterial growth was detected in 90 (10.2%) blood cultures for 95 different isolates, of which 62 (7.1%)/63 isolates were considered clinically significant. Among the latter, 38 (60.3%) microorganisms grew in both aerobic and anaerobic bottles, 18 (28.6%) only in aerobic bottles, and 7 (11.1%) only in anaerobic bottles. Gram-negative bacilli (33; 52.4%), mainly from the Enterobacteriaceae family, were the most frequently isolated microorganisms. Overall, only 3 out of 90 isolates (3.3%) were strict anaerobes (Propionibacterium acnes), and all of them were deemed contaminants. Strict anaerobes did not cause significant infections in febrile pediatric oncology patients, and anaerobic blood culture bottles offered no additional advantages over aerobic media. Our results suggest that routine blood cultures should be solely processed in aerobic media in this group of patients. Copyright © 2016 Elsevier España, S.L.U. and Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica. All rights reserved.

Total solids content: a key parameter of metabolic pathways in dry anaerobic digestion

PubMed Central

2013-01-01

Background In solid-state anaerobic digestion (AD) bioprocesses, hydrolytic and acidogenic microbial metabolisms have not yet been clarified. Since these stages are particularly important for the establishment of the biological reaction, better knowledge could optimize the process performances by process parameters adjustment. Results This study demonstrated the effect of total solids (TS) content on microbial fermentation of wheat straw with six different TS contents ranging from wet to dry conditions (10 to 33% TS). Three groups of metabolic behaviors were distinguished based on wheat straw conversion rates with 2,200, 1,600, and 1,400 mmol.kgVS-1 of fermentative products under wet (10 and 14% TS), dry (19 to 28% TS), and highly dry (28 to 33% TS) conditions, respectively. Furthermore, both wet and dry fermentations showed acetic and butyric acid metabolisms, whereas a mainly butyric acid metabolism occurred in highly dry fermentation. Conclusion Substrate conversion was reduced with no changes of the metabolic pathways until a clear limit at 28% TS content, which corresponded to the threshold value of free water content of wheat straw. This study suggested that metabolic pathways present a limit of TS content for high-solid AD. PMID:24261971

Integration of pyrolysis and anaerobic digestion--use of aqueous liquor from digestate pyrolysis for biogas production.

PubMed

Hübner, Tobias; Mumme, Jan

2015-05-01

Anaerobic digestion of aqueous pyrolysis liquor derived from pyrolysis of solid digestate was tested in batch mode using an un-adapted inoculum. Three pyrolysis liquors produced at 330°C, 430°C and 530°C in four COD-based concentrations of 3, 6, 12 and 30 g L(-1) were investigated. The three lower concentrations showed considerable biogas production, whereas the 30 g L(-1) dosage caused process inhibition. The highest methane yield of 199.1±18.5 mL g(COD)(-1) (COD removal: 56.9±5.3%) was observed for the 330°C pyrolysis liquor, followed by the 430°C sample with only slightly lower values. The 530°C sample dropped to a yield of 129.3±19.7 mL g(COD)(-1) (COD removal: 36.9±5.6%). Most VOCs contained in the pyrolysis liquor (i.e. furfural, phenol, catechol, guaiacol, and levoglucosan) were reduced below detection limit (cresol by 10-60%). Consequently, integrated pyrolysis and anaerobic digestion in addition to thermochemical conversion of digestate also promises bioconversion of pyrolysis liquors. Copyright © 2015 Elsevier Ltd. All rights reserved.

Potential use of the organic fraction of municipal solid waste in anaerobic co-digestion with wastewater in submerged anaerobic membrane technology.

PubMed

Moñino, P; Jiménez, E; Barat, R; Aguado, D; Seco, A; Ferrer, J

2016-10-01

Food waste was characterized for its potential use as substrate for anaerobic co-digestion in a submerged anaerobic membrane bioreactor pilot plant that treats urban wastewater (WW). 90% of the particles had sizes under 0.5mm after grinding the food waste in a commercial food waste disposer. COD, nitrogen and phosphorus concentrations were 100, 2 and 20 times higher in food waste than their average concentrations in WW, but the relative flow contribution of both streams made COD the only pollutant that increased significantly when both substrates were mixed. As sulphate concentration in food waste was in the same range as WW, co-digestion of both substrates would increase the COD/SO4-S ratio and favour methanogenic activity in anaerobic treatments. The average methane potential of the food waste was 421±15mLCH4g(-1)VS, achieving 73% anaerobic biodegradability. The anaerobic co-digestion of food waste with WW is expected to increase methane production 2.9-fold. The settleable solids tests and the particle size distribution analyses confirmed that both treatment lines of a conventional WWTP (water and sludge lines) would be clearly impacted by the incorporation of food waste into its influent. Anaerobic processes are therefore preferred over their aerobic counterparts due to their ability to valorise the high COD content to produce biogas (a renewable energy) instead of increasing the energetic costs associated with the aeration process for aerobic COD oxidation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Anaerobic co-digestion of steam-treated Quercus serrata chips and sewage sludge under mesophilic and thermophilic conditions.

PubMed

Wang, Feng; Hidaka, Taira; Sakurai, Kensuke; Tsumori, Jun

2014-08-01

The biodegradation of Quercus serrata chips was evaluated by anaerobic digestion under various steam explosion conditions. In continuous experiments, untreated chips (W₀) and chips steam-treated at less than 1.0 MPa (W₁) and 2.0 MPa (W₄) were co-digested with sewage sludge (S₁ and S₂) taken from two different wastewater treatment plants. The apparent methane yield of W₁ and W₄ co-digested with S₁ (thermophilic) was 261 dm(3)/kgVS (volatile solids) and 248 dm(3)/kgVS, respectively. The apparent methane yield of W₄ co-digested with S₂ was 258 dm(3)/kgVS (mesophilic) and 271 dm(3)/kgVS (thermophilic). Methane production was inhibited by W₀ due to components released during hydrolysis. The methane conversion ratio of pretreated chips obtained in batch experiments varied from 40.5% to 53.8% (mesophilic) and from 49.0% to 63.7% (thermophilic). The methane conversion ratio increased with decreasing acid-soluble lignin content in the chips. Copyright © 2014 Elsevier Ltd. All rights reserved.

Isolation of a buprofezin co-metabolizing strain of Pseudomonas sp. DFS35-4 and identification of the buprofezin transformation pathway.

PubMed

Chen, Kai; Liu, Xiao-Mei; Li, Rong; Liu, Yuan; Hu, Hai; Li, Shun-Peng; Jiang, Jian-Dong

2011-11-01

Buprofezin is a widely used insecticide that has caused environmental pollution in many areas. However, biodegradation of buprofezin by pure cultures has not been extensively studied, and the transformation pathway of buprofezin remains unclear. In this paper, a buprofezin co-metabolizing strain of DFS35-4 was isolated from a buprofezin-polluted soil in China. Strain DFS35-4 was preliminarily identified as Pseudomonas sp. based on its morphological, physiological, and biochemical properties, as well as 16S rRNA gene analysis. In the presence of 2.0 g l(-1) sodium citrate, strain DFS35-4 degraded over 70% of 50 mg l(-1) buprofezin in 3 days. Strain DFS35-4 efficiently degraded buprofezin in the pH range of 5.0-10.0 and at temperatures between 20 and 30°C. Three metabolites, 2-imino-5-phenyl-3-(propan-2-yl)-1,3,5-thiadiazinan-4-one, 2-imino-5-phenyl-1,3,5-thiadiazinan-4-one, and methyl(phenyl) carbamic acid, were identified during the degradation of buprofezin using gas chromatography-mass spectrometry (GC-MS) and tandem mass spectrometry (MS/MS). A partial transformation pathway of buprofezin in Pseudomonas sp. DFS35-4 was proposed based on these metabolites.

Using contaminated plants involved in phytoremediation for anaerobic digestion.

PubMed

Cao, Zewei; Wang, Shengxiao; Wang, Ting; Chang, Zhizhou; Shen, Zhenguo; Chen, Yahua

2015-01-01

This study investigated the anaerobic digestion capability of five plants and the effects of copper (Cu) and S,S'-ethylenediaminedisuccinic acid (EDDS, a chelator widely used in chelant-assisted phytoremediation) on biogas production to determine a feasible disposal method for plants used in remediation. The results showed that in addition to Phytolacca americana L., plants such as Zea mays L., Brassica napus L., Elsholtzia splendens Nakai ex F. Maekawa, and Oenothera biennis L. performed well in biogas production. Among these, O. biennis required the shortest period to finish anaerobic digestion. Compared to normal plants with low Cu content, the plants used in remediation with increased Cu levels (100 mg kg(-1)) not only promoted anaerobic digestion and required a shorter anaerobic digestion time, but also increased the methane content in biogas. When the Cu content in plants increased to 500, 1000, and 5000 mg kg(-1), the cumulative biogas production decreased by 12.3%, 14.6%, and 41.2%, respectively. Studies also found that EDDS conspicuously restrained biogas production from anaerobic digestion. The results suggest that anaerobic digestion has great potential for the disposal of contaminated plants and may provide a solution for the resource utilization of plants used in remediation.

Anaerobic threshold: its concept and role in endurance sport.

PubMed

Ghosh, Asok Kumar

2004-01-01

aerobic to anaerobic transition intensity is one of the most significant physiological variable in endurance sports. Scientists have explained the term in various ways, like, Lactate Threshold, Ventilatory Anaerobic Threshold, Onset of Blood Lactate Accumulation, Onset of Plasma Lactate Accumulation, Heart Rate Deflection Point and Maximum Lactate Steady State. But all of these have great role both in monitoring training schedule and in determining sports performance. Individuals endowed with the possibility to obtain a high oxygen uptake need to complement with rigorous training program in order to achieve maximal performance. If they engage in endurance events, they must also develop the ability to sustain a high fractional utilization of their maximal oxygen uptake (%VO(2) max) and become physiologically efficient in performing their activity. Anaerobic threshold is highly correlated to the distance running performance as compared to maximum aerobic capacity or VO(2) max, because sustaining a high fractional utilization of the VO(2) max for a long time delays the metabolic acidosis. Training at or little above the anaerobic threshold intensity improves both the aerobic capacity and anaerobic threshold level. Anaerobic Threshold can also be determined from the speed-heart rate relationship in the field situation, without undergoing sophisticated laboratory techniques. However, controversies also exist among scientists regarding its role in high performance sports.

Evaluation and characterization during the anaerobic digestion of high-strength kitchen waste slurry via a pilot-scale anaerobic membrane bioreactor.

PubMed

Xiao, Xiaolan; Huang, Zhenxing; Ruan, Wenquan; Yan, Lintao; Miao, Hengfeng; Ren, Hongyan; Zhao, Mingxing

2015-10-01

The anaerobic digestion of high-strength kitchen waste slurry via a pilot-scale anaerobic membrane bioreactor (AnMBR) was investigated at two different operational modes, including no sludge discharge and daily sludge discharge of 20 L. The AnMBR provided excellent and reliable permeate quality with high COD removal efficiencies over 99%. The obvious accumulations of long chain fatty acids (LCFAs) and Ca(2+) were found in the anaerobic digester by precipitation and agglomeration. Though the physicochemical process contributed to attenuating the free LCFAs toxicity on anaerobic digestion, the digestion efficiency was partly influenced for the low bioavailability of those precipitates. Moreover, higher organic loading rate (OLR) of 5.8 kg COD/(m(3) d) and digestion efficiency of 78% were achieved as the AnMBR was stably operated with sludge discharge, where the membrane fouling propensity was also alleviated, indicating the crucial significance of SRT control on the treatment of high-strength kitchen waste slurry via AnMBRs. Copyright © 2015 Elsevier Ltd. All rights reserved.

Potential use and the energy conversion efficiency analysis of fermentation effluents from photo and dark fermentative bio-hydrogen production.

PubMed

Zhang, Zhiping; Li, Yameng; Zhang, Huan; He, Chao; Zhang, Quanguo

2017-12-01

Effluent of bio-hydrogen production system also can be adopted to produce methane for further fermentation, cogeneration of hydrogen and methane will significantly improve the energy conversion efficiency. Platanus Orientalis leaves were taken as the raw material for photo- and dark-fermentation bio-hydrogen production. The resulting concentrations of acetic, butyric, and propionic acids and ethanol in the photo- and dark-fermentation effluents were 2966mg/L and 624mg/L, 422mg/L and 1624mg/L, 1365mg/L and 558mg/L, and 866mg/L and 1352mg/L, respectively. Subsequently, we calculated the energy conversion efficiency according to the organic contents of the effluents and their energy output when used as raw material for methane production. The overall energy conversion efficiencies increased by 15.17% and 22.28%, respectively, when using the effluents of photo and dark fermentation. This two-step bio-hydrogen and methane production system can significantly improve the energy conversion efficiency of anaerobic biological treatment plants. Copyright © 2017. Published by Elsevier Ltd.

Foaming phenomenon in bench-scale anaerobic digesters.

PubMed

Siebels, Amanda M; Long, Sharon C

2013-04-01

The Madison Metropolitan Sewerage District (The District) in Madison, Wisconsin has been experiencing seasonal foaming in their anaerobic biosolids digesters, which has occurred from mid-November to late June for the past few years. The exact cause(s) of foaming is unknown. Previous research findings are unclear as to whether applications of advanced anaerobic digestion processes reduce the foaming potential of digesters. The object of this study was to investigate how configurations of thermophilic and acid phase-thermophilic anaerobic digestion would affect foaming at the bench-scale level compared to single stage mesophilic digestion for The District. Bench-scale anaerobic digesters were fed with a 4 to 4.5% by dry weight of solids content blend of waste activated sludge (WAS) and primary sludge from The District. Foaming potential was monitored using Alka-Seltzer and aeration foaming tests. The bench-scale acid phase-thermophilic digester had a higher foaming potential than the bench-scale mesophilic digester. These results indicate that higher temperatures increase the foaming potential of the bench-scale anaerobic digesters. The bench-scale acid phase-thermophilic digesters had a greater percent (approximately 5 to 10%) volatile solids destruction and a greater percent (approximately 5 to 10%) total solids destruction when compared to the bench-scale mesophilic digester. Overall, for the full-scale foaming experienced by The District, it appears that adding an acid phase or switching to thermophilic digestion would not alleviate The District's foaming issues.

Anaerobic bacteremia in a neutropenic patient with oral mucositis.

PubMed

Vidal, A M; Sarria, J C; Kimbrough, R C; Keung, Y K

2000-03-01

An increasing number of anaerobic bloodstream infections in neutropenic cancer patients have been reported in the last decade. The type of anaerobes isolated from most of these patients suggests an oral source of infection. We describe a case of anaerobic bacteremia in a neutropenic patient with oral mucositis that highlights the importance of considering these organisms when selecting empiric prophylactic or therapeutic antimicrobial regimens, especially in the setting of periodontal disease or oral mucositis.

DEVELOPMENT OF IMPROVED ANAEROBIC GROWTH OF BACILLUS MOJAVENSIS STRAIN JF-2 FOR THE PURPOSE OF IMPROVED ANAEROBIC BIOSURFACTANT PRODUCTION FOR ENHANCED OIL RECOVERY

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

M.J. McInerney; M. Folmsbee; D. Nagle

2004-05-31

Our work focuses on the use of microorganisms to recover petroleum hydrocarbons that remain entrapped after current recovery technologies reach their economic limit. Capillary forces between the hydrocarbon and aqueous phases are largely responsible for trapping the hydrocarbons in the pores of the rock and large reductions in the interfacial tension between the hydrocarbon and aqueous phases are needed for hydrocarbon mobilization (1-3, 10, 11). Microorganisms produce a variety of biosurfactants (4), several of which generate the ultra low interfacial tensions needed for hydrocarbon mobilization (4, 5, 8). In particular, the lipopeptide biosurfactant produced by Bacillus mojavensis strain JF-2 reducesmore » the interfacial tension between hydrocarbon and aqueous phases to very low levels (<0.016 mN/m) (8) (9). B. mojavensis JF-2 grows under the environmental conditions found in many oil reservoirs, i. e., anaerobic, NaCl concentrations up to 80 g l{sup -1}, and temperatures up to 45 C (6, 7), making it ideally suited for in situ applications. However, anaerobic growth of B. mojavensis JF-2 was inconsistent and difficult to replicate, which limited its use for in situ applications. Our initial studies revealed that enzymatic digests, such as Proteose Peptone, were required for anaerobic growth of Bacillus mojavensis JF-2. Subsequent purification of the growth-enhancing factor in Proteose Peptone resulted in the identification of the growth-enhancing factor as DNA or deoxyribonucleosides. The addition of salmon sperm DNA, herring sperm DNA, E. coli DNA or synthetic DNA (single or double stranded) to Medium E all supported anaerobic growth of JF-2. Further, we found that JF-2 required all four deoxyribonucleosides (deoxyadeonosine, deoxyguanosine, deoxycytidine and thymidine) for growth under strict anaerobic conditions. The requirement for the deoxyribonucleosides did not occur under aerobic growth conditions. DNA was not used as a sole energy source; sucrose was

Anaerobic bacteria in wastewater treatment plant.

PubMed

Cyprowski, Marcin; Stobnicka-Kupiec, Agata; Ławniczek-Wałczyk, Anna; Bakal-Kijek, Aleksandra; Gołofit-Szymczak, Małgorzata; Górny, Rafał L

2018-03-28

The objective of this study was to assess exposure to anaerobic bacteria released into air from sewage and sludge at workplaces from a wastewater treatment plant (WWTP). Samples of both sewage and sludge were collected at six sampling points and bioaerosol samples were additionally collected (with the use of a 6-stage Andersen impactor) at ten workplaces covering different stages of the technological process. Qualitative identification of all isolated strains was performed using the biochemical API 20A test. Additionally, the determination of Clostridium pathogens was carried out using 16S rRNA gene sequence analysis. The average concentration of anaerobic bacteria in the sewage samples was 5.49 × 10 4 CFU/mL (GSD = 85.4) and in sludge-1.42 × 10 6 CFU/g (GSD = 5.1). In turn, the average airborne bacterial concentration was at the level of 50 CFU/m 3 (GSD = 5.83) and the highest bacterial contamination (4.06 × 10 3  CFU/m 3 ) was found in winter at the bar screens. In total, 16 bacterial species were determined, from which the predominant strains belonged to Actinomyces, Bifidobacterium, Clostridium, Propionibacterium and Peptostreptococcus genera. The analysis revealed that mechanical treatment processes were responsible for a substantial emission of anaerobic bacteria into the air. In both the sewage and air samples, Clostridium perfringens pathogen was identified. Anaerobic bacteria were widely present both in the sewage and in the air at workplaces from the WWTP, especially when the technological process was performed in closed spaces. Anaerobic bacteria formed small aggregates with both wastewater droplets and dust particles of sewage sludge origin and as such may be responsible for adverse health outcomes in exposed workers.

Hydroponic system for the treatment of anaerobic liquid.

PubMed

Krishnasamy, K; Nair, J; Bäuml, B

2012-01-01

The effluent from anaerobic digestion process has high concentrations of nutrients, particularly nitrogen, essential for plant growth but is not suitable for direct disposal or application due to high chemical oxygen demand (COD), low dissolved oxygen (DO), odour issues and is potentially phytotoxic. This research explored the optimum conditions of anaerobic effluent for application and dilutions of the effluent required to obtain better plant growth. A small-scale hydroponic system was constructed in a glasshouse to test different concentrations of anaerobic effluent against a commercial hydroponic medium as the control for the growth of silverbeet. It was found that the survival of silverbeet was negatively affected at 50% concentration due to low DO and NH(4) toxicity. The concentration of 20% anaerobic liquid was found to be the most efficient with highest foliage yield and plant growth. The hydroponic system with 20% concentrated effluent had better utilisation of nutrients for plant growth and a COD reduction of 95% was achieved during the 50-day growth period. This preliminary evaluation revealed that the growth and development of silverbeet was significantly lower in anaerobic effluent compared with a commercial hydroponic plant growth solution. The nutrient quality of anaerobic effluent could be highly variable with the process and the waste material used and dilution may depend on the nutrient content of the effluent. It is recommended that, a pre-treatment of the effluent to increase DO and reduce ammonium content is required before plant application, and simple dilution by itself is not suitable for optimum plant growth in a hydroponic system.

The aerobic activity of metronidazole against anaerobic bacteria.

PubMed

Dione, Niokhor; Khelaifia, Saber; Lagier, Jean-Christophe; Raoult, Didier

2015-05-01

Recently, the aerobic growth of strictly anaerobic bacteria was demonstrated using antioxidants. Metronidazole is frequently used to treat infections caused by anaerobic bacteria; however, to date its antibacterial activity was only tested in anaerobic conditions. Here we aerobically tested using antioxidants the in vitro activities of metronidazole, gentamicin, doxycycline and imipenem against 10 common anaerobic and aerobic bacteria. In vitro susceptibility testing was performed by the disk diffusion method, and minimum inhibitory concentrations (MICs) were determined by Etest. Aerobic culture of the bacteria was performed at 37°C using Schaedler agar medium supplemented with 1mg/mL ascorbic acid and 0.1mg/mL glutathione; the pH was adjusted to 7.2 by 10M KOH. Growth of anaerobic bacteria cultured aerobically using antioxidants was inhibited by metronidazole after 72h of incubation at 37°C, with a mean inhibition diameter of 37.76mm and an MIC of 1μg/mL; however, strains remained non-sensitive to gentamicin. No growth inhibition of aerobic bacteria was observed after 24h of incubation at 37°C with metronidazole; however, inhibition was observed with doxycycline and imipenem used as controls. These results indicate that bacterial sensitivity to metronidazole is not related to the oxygen tension but is a result of the sensitivity of the micro-organism. In future, both culture and antibiotic susceptibility testing of strictly anaerobic bacteria will be performed in an aerobic atmosphere using antioxidants in clinical microbiology laboratories. Copyright © 2015 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

Anaerobic Catabolism of Aromatic Compounds: a Genetic and Genomic View

PubMed Central

Carmona, Manuel; Zamarro, María Teresa; Blázquez, Blas; Durante-Rodríguez, Gonzalo; Juárez, Javier F.; Valderrama, J. Andrés; Barragán, María J. L.; García, José Luis; Díaz, Eduardo

2009-01-01

Summary: Aromatic compounds belong to one of the most widely distributed classes of organic compounds in nature, and a significant number of xenobiotics belong to this family of compounds. Since many habitats containing large amounts of aromatic compounds are often anoxic, the anaerobic catabolism of aromatic compounds by microorganisms becomes crucial in biogeochemical cycles and in the sustainable development of the biosphere. The mineralization of aromatic compounds by facultative or obligate anaerobic bacteria can be coupled to anaerobic respiration with a variety of electron acceptors as well as to fermentation and anoxygenic photosynthesis. Since the redox potential of the electron-accepting system dictates the degradative strategy, there is wide biochemical diversity among anaerobic aromatic degraders. However, the genetic determinants of all these processes and the mechanisms involved in their regulation are much less studied. This review focuses on the recent findings that standard molecular biology approaches together with new high-throughput technologies (e.g., genome sequencing, transcriptomics, proteomics, and metagenomics) have provided regarding the genetics, regulation, ecophysiology, and evolution of anaerobic aromatic degradation pathways. These studies revealed that the anaerobic catabolism of aromatic compounds is more diverse and widespread than previously thought, and the complex metabolic and stress programs associated with the use of aromatic compounds under anaerobic conditions are starting to be unraveled. Anaerobic biotransformation processes based on unprecedented enzymes and pathways with novel metabolic capabilities, as well as the design of novel regulatory circuits and catabolic networks of great biotechnological potential in synthetic biology, are now feasible to approach. PMID:19258534

Anaerobic soil disinfestation and soil borne pest management

USDA-ARS?s Scientific Manuscript database

Anaerobic soil disinfestation (ASD; also referred to as Biological Soil Disinfestation (BSD)) is a pre-plant soil treatment method developed to control plant disease and manage yield decline in many crop production systems. The practice involves induction of anaerobic soil conditions by increasing m...

Process simulation and comparison of biological conversion of syngas and hydrogen in biogas plants

NASA Astrophysics Data System (ADS)

Awais Salman, Chaudhary; Schwede, Sebastian; Thorin, Eva; Yan, Jinyue

2017-11-01

Organic waste is a good source of clean energy. However, different fractions of waste have to be utilized efficiently. One way is to find pathways to convert waste into useful products via various available processes (gasification, pyrolysis anaerobic digestion, etc.) and integrate them to increase the combined efficiency of the process. The syngas and hydrogen produced from the thermal conversion of biomass can be upgraded to biomethane via biological methanation. The current study presents the simulation model to predict the amount of biomethane produced by injecting the hydrogen and syngas. Hydrogen injection is modelled both in-situ and ex-situ while for syngas solely the ex-situ case has been studied. The results showed that 85% of the hydrogen conversion was achieved for the ex-situ reactor while 81% conversion rate was achieved for the in-situ reactor. The syngas could be converted completely in the bio-reactor. However, the addition of syngas resulted in an increase of carbon dioxide. Simulation of biomethanation of gas addition showed a biomethane concentration of 87% while for hydrogen addition an increase of 74% and 80% for in-situ and ex-situ addition respectively.

Anaerobic Degradation of Benzene and Polycyclic Aromatic Hydrocarbons.

PubMed

Meckenstock, Rainer U; Boll, Matthias; Mouttaki, Housna; Koelschbach, Janina S; Cunha Tarouco, Paola; Weyrauch, Philip; Dong, Xiyang; Himmelberg, Anne M

2016-01-01

Aromatic hydrocarbons such as benzene and polycyclic aromatic hydrocarbons (PAHs) are very slowly degraded without molecular oxygen. Here, we review the recent advances in the elucidation of the first known degradation pathways of these environmental hazards. Anaerobic degradation of benzene and PAHs has been successfully documented in the environment by metabolite analysis, compound-specific isotope analysis and microcosm studies. Subsequently, also enrichments and pure cultures were obtained that anaerobically degrade benzene, naphthalene or methylnaphthalene, and even phenanthrene, the largest PAH currently known to be degradable under anoxic conditions. Although such cultures grow very slowly, with doubling times of around 2 weeks, and produce only very little biomass in batch cultures, successful proteogenomic, transcriptomic and biochemical studies revealed novel degradation pathways with exciting biochemical reactions such as for example the carboxylation of naphthalene or the ATP-independent reduction of naphthoyl-coenzyme A. The elucidation of the first anaerobic degradation pathways of naphthalene and methylnaphthalene at the genetic and biochemical level now opens the door to studying the anaerobic metabolism and ecology of anaerobic PAH degraders. This will contribute to assessing the fate of one of the most important contaminant classes in anoxic sediments and aquifers. © 2016 S. Karger AG, Basel.

Anaerobic digestion of selected Italian agricultural and industrial residues (grape seeds and leather dust): combined methane production and digestate characterization.

PubMed

Caramiello, C; Lancellotti, I; Righi, F; Tatàno, F; Taurino, R; Barbieri, L

2013-01-01

A combined experimental evaluation of methane production (obtained by anaerobic digestion) and detailed digestate characterization (with physical-chemical, thermo-gravimetric and mineralogical approaches) was conducted on two organic substrates, which are specific to Italy (at regional and national levels). One of the substrates was grape seeds, which have an agricultural origin, whereas the other substrate was vegetable-tanned leather dust, which has an industrial origin. Under the assumed experimental conditions of the performed lab-scale test series, the grape seed substrate exhibited a resulting net methane production of 175.0 NmL g volatile solids (VS)(-1); hence, it can be considered as a potential energy source via anaerobic digestion. Conversely, the net methane production obtained from the anaerobic digestion of the vegetable-tanned leather dust substrate was limited to 16.1 NmL gVS(-1). A detailed characterization of the obtained digestates showed that there were both nitrogen-containing compounds and complex organic compounds present in the digestate that was obtained from the mixture of leather dust and inoculum. As a general perspective of this experimental study, the application of diversified characterization analyzes could facilitate (1) a better understanding of the main properties of the obtained digestates to evaluate their potential valorization, and (2) a combination of the digestate characteristics with the corresponding methane productions to comprehensively evaluate the bioconversion process.

Product toxicity and cometabolic competitive inhibition modeling of chloroform and trichloroethylene transformation by methanotrophic resting cells.

PubMed Central

Alvarez-Cohen, L; McCarty, P L

1991-01-01

The rate and capacity for chloroform (CF) and trichloroethylene (TCE) transformation by a mixed methanotrophic culture of resting cells (no exogenous energy source) and formate-fed cells were measured. As reported previously for TCE, formate addition resulted in an increased CF transformation rate (0.35 day-1 for resting cells and 1.5 day-1 for formate-fed cells) and transformation capacity (0.0065 mg of CF per mg of cells for resting cells and 0.015 mg of CF per mg of cells for formate-fed cells), suggesting that depletion of energy stores affects transformation behavior. The observed finite transformation capacity, even with an exogenous energy source, suggests that toxicity was also a factor. CF transformation capacity was significantly lower than that for TCE, suggesting a greater toxicity from CF transformation. The toxicity of CF, TCE, and their transformation products to whole cells was evaluated by comparing the formate oxidation activity of acetylene-treated cells to that of non-acetylene-treated cells with and without prior exposure to CF or TCE. Acetylene arrests the activity of methane monooxygenase in CF and TCE oxidation without halting cell activity toward formate. Significantly diminished formate oxidation by cells exposed to either CR or TCE without acetylene compared with that with acetylene suggests that the solvents themselves were not toxic under the experimental conditions but their transformation products were. The concurrent transformation of CF and TCE by resting cells was measured, and results were compared with predictions from a competitive-inhibition cometabolic transformation model. The reasonable fit between model predictions and experimental observations was supportive of model assumptions. PMID:1905516

Microbiology and management of joint and bone infections due to anaerobic bacteria.

PubMed

Brook, Itzhak

2008-03-01

To describes the microbiology, diagnosis, and management of septic arthritis and osteomyelitis due to anaerobic bacteria. The predominant anaerobes in arthritis are anaerobic Gram-negative bacilli (AGNB) including the Bacteroides fragilis group, Fusobacterium spp., Peptostreptococcus spp., and Propionibacterium acnes. Infection with P. acnes is associated with a prosthetic joint, previous surgery, and trauma. B. fragilis group is associated with distant infection, Clostridium spp. with trauma, and Fusobacterium spp. with oropharyngeal infection. Most cases of anaerobic arthritis, in contrast to anaerobic osteomyelitis, involved a single isolate, and most cases are secondary to hematogenous spread. The predominant anaerobes in osteomyelitis are Bacteroides, Peptostreptococcus, Fusobacterium, and Clostridium spp. as well as P. acnes. Conditions predisposing to bone infections are vascular disease, bites, contiguous infection, peripheral neuropathy, hematogenous spread, and trauma. Pigmented Prevotella and Porphyromonas spp. are mostly isolated in skull and bite infections, members of the B. fragilis group in hand and feet infections, and Fusobacterium spp. in skull, bite, and hematogenous long bone infections. Many patients with osteomyelitis due to anaerobic bacteria have evidence of an anaerobic infection elsewhere in the body that is the source of the organisms involved in the osteomyelitis. Treatment of arthritis and osteomyelitis involving anaerobic bacteria includes symptomatic therapy, immobilization in some cases, adequate drainage of purulent material, and antibiotic therapy effective against these organisms. Anaerobic bacteria can cause septic arthritis and osteomyelitis. Correct diagnosis and appropriate therapy are important contributor to successful outcome.

Clinical evaluation of the Vitek ANI card for identification of anaerobic bacteria.

PubMed Central

Schreckenberger, P C; Celig, D M; Janda, W M

1988-01-01

An evaluation of the Vitek Anaerobe Identification (ANI) card was performed with 341 bacterial isolates, including 313 clinical isolates and 28 stock strains of anaerobic microorganisms. Identifications obtained with the ANI card were compared with those determined by conventional methods. The card identified 73.2% of 149 anaerobic gram-negative bacilli, 63.6% of 44 Clostridium spp., 65.8% of 38 anaerobic nonsporeforming gram-positive bacilli, and 69.1% of 110 anaerobic cocci, with no further testing required. When genus-level identifications were included, 83.9% of the anaerobic gram-negative bacilli, 70.5% of Clostridium spp., 73.7% of the anaerobic nonsporeforming gram-positive bacilli, and 73.6% of the anaerobic cocci were identified. Nineteen isolates (5.6%) produced identifications of good confidence but marginal separation or questionable biotype, in which the correct identification was listed with one or two other possible choices and extra tests were required and suggested. A total of 28 (8.2%) were not identified and 29 isolates (8.5%) were misidentified by the ANI card. Among the commonly isolated clinically significant anaerobes, the ANI card identified 100% of 55 Bacteroides fragilis and 100% of 8 Clostridium perfringens. Use of supplemental tests and expansion of the data base to include additional strains of organisms that are difficult to separate even with conventional methods may improve the accuracy of the ANI card as a method for identification of anaerobic bacteria in the clinical laboratory. PMID:3343321

Anaerobes as Sources of Bioactive Compounds and Health Promoting Tools.

PubMed

Mamo, Gashaw

Aerobic microorganisms have been sources of medicinal agents for several decades and an impressive variety of drugs have been isolated from their cultures, studied and formulated to treat or prevent diseases. On the other hand, anaerobes, which are believed to be the oldest life forms on earth and evolved remarkably diverse physiological functions, have largely been neglected as sources of bioactive compounds. However, results obtained from the limited research done so far show that anaerobes are capable of producing a range of interesting bioactive compounds that can promote human health. In fact, some of these bioactive compounds are found to be novel in their structure and/or mode of action.Anaerobes play health-promoting roles through their bioactive products as well as application of whole cells. The bioactive compounds produced by these microorganisms include antimicrobial agents and substances such as immunomodulators and vitamins. Bacteriocins produced by anaerobes have been in use as preservatives for about 40 years. Because these substances are effective at low concentrations, encounter relatively less resistance from bacteria and are safe to use, there is a growing interest in these antimicrobial agents. Moreover, several antibiotics have been reported from the cultures of anaerobes. Closthioamide and andrimid produced by Clostridium cellulolyticum and Pantoea agglomerans, respectively, are examples of novel antibiotics of anaerobe origin. The discovery of such novel bioactive compounds is expected to encourage further studies which can potentially lead to tapping of the antibiotic production potential of this fascinating group of microorganisms.Anaerobes are widely used in preparation of fermented foods and beverages. During the fermentation processes, these organisms produce a number of bioactive compounds including anticancer, antihypertensive and antioxidant substances. The well-known health promoting effect of fermented food is mostly due to these

Anaerobic mineralization of vinyl chloride in Fe(III)-reducing, aquifer sediments

USGS Publications Warehouse

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

1996-01-01

Within anaerobic aquifer systems, reductive dehalogenation of polychlorinated ethenes commonly results in the accumulation of vinyl chloride, which is highly toxic and carcinogenic to humans. Anaerobic reduction of vinyl chloride is considered to be slow and incomplete. Here, we provide the first evidence for anaerobic oxidation of vinyl chloride under Fe(III)reducing conditions. Addition of chelated Fe(III) (as Fe-EDTA) to anaerobic aquifer microcosms resulted in mineralization of up to 34% of [1,2- 14C]vinyl chloride within 84 h. The results indicate that vinyl chloride can be mineralized under anaerobic, Fe(III)-reducing conditions and that the bioavailability of Fe(III) is an important factor affecting the rates of mineralization.

[Anaerobic digestion of lignocellulosic biomass with animal digestion mechanisms].

PubMed

Wu, Hao; Zhang, Pan-Yue; Guo, Jian-Bin; Wu, Yong-Jie

2013-02-01

Lignocellulosic material is the most abundant renewable resource in the earth. Herbivores and wood-eating insects are highly effective in the digestion of plant cellulose, while anaerobic digestion process simulating animal alimentary tract still remains inefficient. The digestion mechanisms of herbivores and wood-eating insects and the development of anaerobic digestion processes of lignocellulose were reviewed for better understanding of animal digestion mechanisms and their application in design and operation of the anaerobic digestion reactor. Highly effective digestion of lignocellulosic materials in animal digestive system results from the synergistic effect of various digestive enzymes and a series of physical and biochemical reactions. Microbial fermentation system is strongly supported by powerful pretreatment, such as rumination of ruminants, cellulase catalysis and alkali treatment in digestive tract of wood-eating insects. Oxygen concentration gradient along the digestive tract may stimulate the hydrolytic activity of some microorganisms. In addition, the excellent arrangement of solid retention time, digesta flow and end product discharge enhance the animal digestion of wood cellulose. Although anaerobic digestion processes inoculated with rumen microorganisms based rumen digestion mechanisms were developed to treat lignocellulose, the fermentation was more greatly limited by the environmental conditions in the anaerobic digestion reactors than that in rumen or hindgut. Therefore, the anaerobic digestion processes simulating animal digestion mechanisms can effectively enhance the degradation of wood cellulose and other organic solid wastes.

Anaerobic Threshold: Its Concept and Role in Endurance Sport

PubMed Central

Ghosh, Asok Kumar

2004-01-01

aerobic to anaerobic transition intensity is one of the most significant physiological variable in endurance sports. Scientists have explained the term in various ways, like, Lactate Threshold, Ventilatory Anaerobic Threshold, Onset of Blood Lactate Accumulation, Onset of Plasma Lactate Accumulation, Heart Rate Deflection Point and Maximum Lactate Steady State. But all of these have great role both in monitoring training schedule and in determining sports performance. Individuals endowed with the possibility to obtain a high oxygen uptake need to complement with rigorous training program in order to achieve maximal performance. If they engage in endurance events, they must also develop the ability to sustain a high fractional utilization of their maximal oxygen uptake (%VO2 max) and become physiologically efficient in performing their activity. Anaerobic threshold is highly correlated to the distance running performance as compared to maximum aerobic capacity or VO2 max, because sustaining a high fractional utilization of the VO2 max for a long time delays the metabolic acidosis. Training at or little above the anaerobic threshold intensity improves both the aerobic capacity and anaerobic threshold level. Anaerobic Threshold can also be determined from the speed-heart rate relationship in the field situation, without undergoing sophisticated laboratory techniques. However, controversies also exist among scientists regarding its role in high performance sports. PMID:22977357

Diversity of anaerobic microbes in spacecraft assembly clean rooms.

PubMed

Probst, Alexander; Vaishampayan, Parag; Osman, Shariff; Moissl-Eichinger, Christine; Andersen, Gary L; Venkateswaran, Kasthuri

2010-05-01

Although the cultivable and noncultivable microbial diversity of spacecraft assembly clean rooms has been previously documented using conventional and state-of-the-art molecular techniques, the occurrence of obligate anaerobes within these clean rooms is still uncertain. Therefore, anaerobic bacterial communities of three clean-room facilities were analyzed during assembly of the Mars Science Laboratory rover. Anaerobic bacteria were cultured on several media, and DNA was extracted from suitable anaerobic enrichments and examined with conventional 16S rRNA gene clone library, as well as high-density phylogenetic 16S rRNA gene microarray (PhyloChip) technologies. The culture-dependent analyses predominantly showed the presence of clostridial and propionibacterial strains. The 16S rRNA gene sequences retrieved from clone libraries revealed distinct microbial populations associated with each clean-room facility, clustered exclusively within gram-positive organisms. PhyloChip analysis detected a greater microbial diversity, spanning many phyla of bacteria, and provided a deeper insight into the microbial community structure of the clean-room facilities. This study presents an integrated approach for assessing the anaerobic microbial population within clean-room facilities, using both molecular and cultivation-based analyses. The results reveal that highly diverse anaerobic bacterial populations persist in the clean rooms even after the imposition of rigorous maintenance programs and will pose a challenge to planetary protection implementation activities.

Compatibility of High-Moisture Storage for Biochemical Conversion of Corn Stover: Storage Performance at Laboratory and Field Scales.

PubMed

Wendt, Lynn M; Murphy, J Austin; Smith, William A; Robb, Thomas; Reed, David W; Ray, Allison E; Liang, Ling; He, Qian; Sun, Ning; Hoover, Amber N; Nguyen, Quang A

2018-01-01

Wet anaerobic storage of corn stover can provide a year-round supply of feedstock to biorefineries meanwhile serving an active management approach to reduce the risks associated with fire loss and microbial degradation. Wet logistics systems employ particle size reduction early in the supply chain through field-chopping which removes the dependency on drying corn stover prior to baling, expands the harvest window, and diminishes the biorefinery size reduction requirements. Over two harvest years, in-field forage chopping was capable of reducing over 60% of the corn stover to a particle size of 6 mm or less. Aerobic and anaerobic storage methods were evaluated for wet corn stover in 100 L laboratory reactors. Of the methods evaluated, traditional ensiling resulted in <6% total solid dry matter loss (DML), about five times less than the aerobic storage process and slightly less than half that of the anaerobic modified-Ritter pile method. To further demonstrate the effectiveness of the anaerobic storage, a field demonstration was completed with 272 dry tonnes of corn stover; DML averaged <5% after 6 months. Assessment of sugar release as a result of dilute acid or dilute alkaline pretreatment and subsequent enzymatic hydrolysis suggested that when anaerobic conditions were maintained in storage, sugar release was either similar to or greater than as-harvested material depending on the pretreatment chemistry used. This study demonstrates that wet logistics systems offer practical benefits for commercial corn stover supply, including particle size reduction during harvest, stability in storage, and compatibility with biochemical conversion of carbohydrates for biofuel production. Evaluation of the operational efficiencies and costs is suggested to quantify the potential benefits of a fully-wet biomass supply system to a commercial biorefinery.

Compatibility of High-Moisture Storage for Biochemical Conversion of Corn Stover: Storage Performance at Laboratory and Field Scales

PubMed Central

Wendt, Lynn M.; Murphy, J. Austin; Smith, William A.; Robb, Thomas; Reed, David W.; Ray, Allison E.; Liang, Ling; He, Qian; Sun, Ning; Hoover, Amber N.; Nguyen, Quang A.

2018-01-01

Wet anaerobic storage of corn stover can provide a year-round supply of feedstock to biorefineries meanwhile serving an active management approach to reduce the risks associated with fire loss and microbial degradation. Wet logistics systems employ particle size reduction early in the supply chain through field-chopping which removes the dependency on drying corn stover prior to baling, expands the harvest window, and diminishes the biorefinery size reduction requirements. Over two harvest years, in-field forage chopping was capable of reducing over 60% of the corn stover to a particle size of 6 mm or less. Aerobic and anaerobic storage methods were evaluated for wet corn stover in 100 L laboratory reactors. Of the methods evaluated, traditional ensiling resulted in <6% total solid dry matter loss (DML), about five times less than the aerobic storage process and slightly less than half that of the anaerobic modified-Ritter pile method. To further demonstrate the effectiveness of the anaerobic storage, a field demonstration was completed with 272 dry tonnes of corn stover; DML averaged <5% after 6 months. Assessment of sugar release as a result of dilute acid or dilute alkaline pretreatment and subsequent enzymatic hydrolysis suggested that when anaerobic conditions were maintained in storage, sugar release was either similar to or greater than as-harvested material depending on the pretreatment chemistry used. This study demonstrates that wet logistics systems offer practical benefits for commercial corn stover supply, including particle size reduction during harvest, stability in storage, and compatibility with biochemical conversion of carbohydrates for biofuel production. Evaluation of the operational efficiencies and costs is suggested to quantify the potential benefits of a fully-wet biomass supply system to a commercial biorefinery. PMID:29632861

Flux analysis of the human proximal colon using anaerobic digestion model 1.

PubMed

Motelica-Wagenaar, Anne Marieke; Nauta, Arjen; van den Heuvel, Ellen G H M; Kleerebezem, Robbert

2014-08-01

The colon can be regarded as an anaerobic digestive compartment within the gastro intestinal tract (GIT). An in silico model simulating the fluxes in the human proximal colon was developed on basis of the anaerobic digestion model 1 (ADM1), which is traditionally used to model waste conversion to biogas. Model calibration was conducted using data from in vitro fermentation of the proximal colon (TIM-2), and, amongst others, supplemented with the bio kinetics of prebiotic galactooligosaccharides (GOS) fermentation. The impact of water and solutes absorption by the host was also included. Hydrolysis constants of carbohydrates and proteins were estimated based on total short chain fatty acids (SCFA) and ammonia production in vitro. Model validation was established using an independent dataset of a different in vitro model: an in vitro three-stage continuous culture system. The in silico model was shown to provide quantitative insight in the microbial community structure in terms of functional groups, and the substrate and product fluxes between these groups as well as the host, as a function of the substrate composition, pH and the solids residence time (SRT). The model confirms the experimental observation that methanogens are washed out at low pH or low SRT-values. The in silico model is proposed as useful tool in the design of experimental setups for in vitro experiments by giving insight in fermentation processes in the proximal human colon. Copyright © 2014. Published by Elsevier Ltd.

Mitigation of Humic Acid Inhibition in Anaerobic Digestion of Cellulose by Addition of Various Salts

PubMed Central

Azman, Samet; Khadem, Ahmad F.; Zeeman, Grietje; van Lier, Jules B.; Plugge, Caroline M.

2015-01-01

Humic compounds are inhibitory to the anaerobic hydrolysis of cellulosic biomass. In this study, the impact of salt addition to mitigate the inhibitory effects of humic compounds was investigated. The experiment was conducted using batch tests to monitor the anaerobic hydrolysis of cellulose in the presence of humic acid. Sodium, potassium, calcium, magnesium and iron salts were tested separately for their efficiency to mitigate humic acid inhibition. All experiments were done under mesophilic conditions (30 °C) and at pH 7. Methane production was monitored online, using the Automatic Methane Potential Test System. Methane production, soluble chemical oxygen demand and volatile fatty acid content of the samples were measured to calculate the hydrolysis efficiencies. Addition of magnesium, calcium and iron salts clearly mitigated the inhibitory effects of humic acid and hydrolysis efficiencies reached up to 75%, 65% and 72%, respectively, which were similar to control experiments. Conversely, potassium and sodium salts addition did not mitigate the inhibition and hydrolysis efficiencies were found to be less than 40%. Mitigation of humic acid inhibition via salt addition was also validated by inductively coupled plasma atomic emission spectroscopy analyses, which showed the binding capacity of different cations to humic acid. PMID:28955013

Degradation characteristics of polylactide in thermophilic anaerobic digestion with hyperthermophilic solubilization condition.

PubMed

Wang, F; Hidaka, T; Oishi, T; Osumi, S; Tsubota, J; Tsuno, H

2011-01-01

To test whether hyperthermophilic treatment promotes polylactide (PLA) dissolution and methane conversion under anaerobic digestion conditions, a single thermophilic control reactor (55 °C) and a two-phase system consisting of a hyperthermophilic reactor (80 °C) and a thermophilic reactor (55 °C) were continuously fed with a mixture of PLA and artificial kitchen garbage. In Runs 1 and 2, the PLA dissolution ratios in the two-phase system were 79.2 ± 6.5% and 85.2 ± 7.0%, respectively, higher than those of the control. Batch experimental results indicated that hyperthermophilic treatment could promote PLA dissolution to a greater degree as compared with single thermophilic treatment and that ammonia addition also had a promotional effect on PLA dissolution. In the two-phase system, after hyperthermophilic treatment, dissolved PLA was converted to methane gas under the subsequent thermophilic condition.

Anaerobic methanotrophy in tidal wetland: Effects of electron acceptors

NASA Astrophysics Data System (ADS)

Lin, Li-Hung; Yu, Zih-Huei; Wang, Pei-Ling

2016-04-01

Wetlands have been considered to represent the largest natural source of methane emission, contributing substantially to intensify greenhouse effect. Despite in situ methanogenesis fueled by organic degradation, methanotrophy also plays a vital role in controlling the exact quantity of methane release across the air-sediment interface. As wetlands constantly experience various disturbances of anthropogenic activities, biological burrowing, tidal inundation, and plant development, rapid elemental turnover would enable various electron acceptors available for anaerobic methanotrophy. The effects of electron acceptors on stimulating anaerobic methanotrophy and the population compositions involved in carbon transformation in wetland sediments are poorly explored. In this study, sediments recovered from tidally influenced, mangrove covered wetland in northern Taiwan were incubated under the static conditions to investigate whether anaerobic methanotrophy could be stimulated by the presence of individual electron acceptors. Our results demonstrated that anaerobic methanotrophy was clearly stimulated in incubations amended with no electron acceptor, sulfate, or Fe-oxyhydroxide. No apparent methane consumption was observed in incubations with nitrate, citrate, fumarate or Mn-oxides. Anaerobic methanotrophy in incubations with no exogenous electron acceptor appears to proceed at the greatest rates, being sequentially followed by incubations with sulfate and Fe-oxyhydroxide. The presence of basal salt solution stimulated methane oxidation by a factor of 2 to 3. In addition to the direct impact of electron acceptor and basal salts, incubations with sediments retrieved from low tide period yielded a lower rate of methane oxidation than from high tide period. Overall, this study demonstrates that anaerobic methanotrophy in wetland sediments could proceed under various treatments of electron acceptors. Low sulfate content is not a critical factor in inhibiting methane

Anaerobic Biotransformation and Mobility of Pu and of Pu-EDTA

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

Xun, Luying

2009-11-20

The enhanced mobility of radionuclides by co-disposed chelating agent, ethylenediaminetetraacetate (EDTA), is likely to occur only under anaerobic conditions. Our extensive effort to enrich and isolate anaerobic EDTA-degrading bacteria has failed. Others has tried and also failed. To explain the lack of anaerobic biodegradation of EDTA, we proposed that EDTA has to be transported into the cells for metabolism. A failure of uptake may contribute to the lack of EDTA degradation under anaerobic conditions. We demonstrated that an aerobic EDTA-degrading bacterium strain BNC1 uses an ABC-type transporter system to uptake EDTA. The system has a periplasmic binding protein that bindmore » EDTA and then interacts with membrane proteins to transport EDTA into the cell at the expense of ATP. The bind protein EppA binds only free EDTA with a Kd of 25 nM. The low Kd value indicates high affinity. However, the Kd value of Ni-EDTA is 2.4 x 10^(-10) nM, indicating much stronger stability. Since Ni and other trace metals are essential for anaerobic respiration, we conclude that the added EDTA sequestrates all trace metals and making anaerobic respiration impossible. Thus, the data explain the lack of anaerobic enrichment cultures for EDTA degradation. Although we did not obtain an EDTA degrading culture under anaerobic conditions, our finding may promote the use of certain metals that forms more stable metal-EDTA complexes than Pu(III)-EDTA to prevent the enhanced mobility. Further, our data explain why EDTA is the most dominant organic pollutant in surface waters, due to the lack of degradation of certain metal-EDTA complexes.« less

Bioenergy from stillage anaerobic digestion to enhance the energy balance ratio of ethanol production.

PubMed

Fuess, Lucas Tadeu; Garcia, Marcelo Loureiro

2015-10-01

The challenges associated with the availability of fossil fuels in the past decades intensified the search for alternative energy sources, based on an ever-increasing demand for energy. In this context, the application of anaerobic digestion (AD) as a core treatment technology in industrial plants should be highlighted, since this process combines the pollution control of wastewaters and the generation of bioenergy, based on the conversion of the organic fraction to biogas, a methane-rich gaseous mixture that may supply the energetic demands in industrial plants. In this context, this work aimed at assessing the energetic potential of AD applied to the treatment of stillage, the main wastewater from ethanol production, in an attempt to highlight the improvements in the energy balance ratio of ethanol by inserting the heating value of methane as a bioenergy source. At least 5-15% of the global energy consumption in the ethanol industry could be supplied by the energetic potential of stillage, regardless the feedstock (i.e. sugarcane, corn or cassava). The association between bagasse combustion and stillage anaerobic digestion in sugarcane-based distilleries could provide a bioenergy surplus of at least 130% of the total fossil fuel input into the ethanol plant, considering only the energy from methane. In terms of financial aspects, the economic gains could reach US$ 0.1901 and US$ 0.0512 per liter of produced ethanol, respectively for molasses- (Brazil) and corn-based (EUA) production chains. For large-scale (∼1000 m(3)EtOH per day) Brazilian molasses-based plants, an annual economic gain of up to US$ 70 million could be observed. Considering the association between anaerobic and aerobic digestion, for the scenarios analyzed, at least 25% of the energetic potential of stillage would be required to supply the energy consumption with aeration, however, more suitable effluents for agricultural application could be produced. The main conclusion from this work

A Genomic Analysis of Anaerobic Aromatic Degradation

DTIC Science & Technology

2004-07-26

bacterium Rhodopseudomonas palustris . Nature Biotech. 22: 55-61. Harrison, F. H. and C. S. Harwood. Identification of a fatty acid ß-oxidation operon...from Rhodopseudomonas palustris that is involved in the latter stages of anaerobic benzoate degradation. Submitted. b. Papers presented at meetings. (MS...in preparation). Samanta, S. K. and C. S. Harwood. 2002. The anaerobic degradation of 3-chlorobenzoate by Rhodopseudomonas palustris strain RCB100

Effect of low solids retention time and focused pulsed pre-treatment on anaerobic digestion of waste activated sludge.

PubMed

Lee, Il-Su; Rittmann, Bruce E

2011-02-01

The interacting effects of Focused Pulsed (FP) treatment and solids retention time (SRT) were evaluated in laboratory-scale digesters operated at SRTs of 2-20 days. Anaerobic digestion and methanogenesis of waste activated sludge (WAS) were stable for SRT ≥ 5 days, but the effluent soluble organic compounds increased significantly for SRT=2 days due to a combination of faster hydrolysis kinetics and washout of methanogens. FP treatment increased the CH(4) production rate and TCOD removal efficiency by up to 33% and 18%, respectively, at a SRT of 20 days. These effects were the result of an increase in the hydrolysis rate, since the concentrations of soluble components remained low for SRT ≥ 5 days. Alternately, FP pre-treatment of WAS allowed the same conversion of TCOD to CH(4) with a smaller SRT and digester size: e.g., 40% size savings with a CH(4) conversion of 0.23 g CH(4)-COD/g COD(in). Copyright © 2010 Elsevier Ltd. All rights reserved.

Operation of an anaerobic filter compared with an anaerobic moving bed bioreactor for the treatment of waste water from hydrothermal carbonisation of fine mulch.

PubMed

Meier, J F; Austermann-Haun, U; Fettig, J; Liebe, H; Wichern, M

2017-10-01

This experimental study investigates the anaerobic digestion of waste water from hydrothermal carbonisation of fine mulch (wood chips) in combination with a co-substrate for the first time. Two anaerobic reactors, an anaerobic filter (AF) and an anaerobic moving bed bioreactor (AnMBBR), were operated over a period of 131 days at mesophilic conditions. The organic loading rate was increased to a maximum of 8.5 g L -l d -1 in the AF and the AnMBBR. Both reactors achieved similarly efficient chemical oxygen demand removal rates of 80% approximately (approx.) and high methane production rates of approx. 2.7 L L -1 d -1 . Nevertheless, signs of an inhibition were observed during the experiments.

Anaerobic carbon metabolism by the tricarboxylic acid cycle

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

Vanlerberghe, G.C.; Horsey, A.K.; Weger, H.G.

Nitrogen-limited cells of Selenastrum minutum (Naeg.) Collins are able to assimilate NH{sub 4}{sup +} in the dark under anaerobic conditions. Addition of NH{sub 4}{sup +} to anaerobic cells results in a threefold increase in tricarboxylic acid cycle (TCAC) CO{sub 2} efflux and an eightfold increase in the rate of anaplerotic carbon fixation via phosphoenspyruvate carboxylase. Both of these observations are consistent with increased TCAC carbon flow to supply intermediates for amino acid biosynthesis. Addition of H{sup 14}CO{sub 3}{sup {minus}} to anaerobic cells assimilating NH{sub 4}{sup +} results in the incorporation of radiolabel into the {alpha}-carboxyl carbon of glutamic acid. Incorporationmore » of radiolabel into glutamic acid is not simply a short-term phenomenon following NH{sub 4}{sup +} addition as the specific activity of glutamic acid increases over time. This indicates that this alga is able to maintain partial oxidative TCAC carbon flow while under anoxia to supply {alpha}ketoglutarate for glutamate production. During dark aerobic NH{sub 4}{sup +} assimilation, no radiolabel appears in fumarate or succinate and only a small amount occurs in malate. During anaerobic NH{sub 4}{sup +} assimilation, these metabolites contain a large proportion of the total radiolabel and radiolabel accumulates in succinate over time. Also, the ratio of dark carbon fixation to NH{sub 4}{sup +} assimilation is much higher under anaerobic than aerobic conditions. These observations suggest the operation of a partial reductive TCAC from oxaloacetic acid to malate, fumarate, and succinate. Such a pathway might contribute to redox balance in an anaerobic cell maintaining partial oxidative TCAC activity.« less

Evaluation of different types of anaerobic seed sludge for the high rate anaerobic digestion of pig slurry in UASB reactors.

PubMed

Rico, Carlos; Montes, Jesús A; Rico, José Luis

2017-08-01

Three different types of anaerobic sludge (granular, thickened digestate and anaerobic sewage) were evaluated as seed inoculum sources for the high rate anaerobic digestion of pig slurry in UASB reactors. Granular sludge performance was optimal, allowing a high efficiency process yielding a volumetric methane production rate of 4.1LCH 4 L -1 d -1 at 1.5days HRT (0.248LCH 4 g -1 COD) at an organic loading rate of 16.4gCODL -1 d -1 . The thickened digestate sludge experimented flotation problems, thus resulting inappropriate for the UASB process. The anaerobic sewage sludge reactor experimented biomass wash-out, but allowed high process efficiency operation at 3days HRT, yielding a volumetric methane production rate of 1.7LCH 4 L -1 d -1 (0.236LCH 4 g -1 COD) at an organic loading rate of 7.2gCODL -1 d -1 . To guarantee the success of the UASB process, the settleable solids of the slurry must be previously removed. Copyright © 2017 Elsevier Ltd. All rights reserved.

Rapid establishment of thermophilic anaerobic microbial community during the one-step startup of thermophilic anaerobic digestion from a mesophilic digester.

PubMed

Tian, Zhe; Zhang, Yu; Li, Yuyou; Chi, Yongzhi; Yang, Min

2015-02-01

The purpose of this study was to explore how fast the thermophilic anaerobic microbial community could be established during the one-step startup of thermophilic anaerobic digestion from a mesophilic digester. Stable thermophilic anaerobic digestion was achieved within 20 days from a mesophilic digester treating sewage sludge by adopting the one-step startup strategy. The succession of archaeal and bacterial populations over a period of 60 days after the temperature increment was followed by using 454-pyrosequencing and quantitative PCR. After the increase of temperature, thermophilic methanogenic community was established within 11 days, which was characterized by the fast colonization of Methanosarcina thermophila and two hydrogenotrophic methanogens (Methanothermobacter spp. and Methanoculleus spp.). At the same time, the bacterial community was dominated by Fervidobacterium, whose relative abundance rapidly increased from 0 to 28.52 % in 18 days, followed by other potential thermophilic genera, such as Clostridium, Coprothermobacter, Anaerobaculum and EM3. The above result demonstrated that the one-step startup strategy could allow the rapid establishment of the thermophilic anaerobic microbial community. Copyright © 2014 Elsevier Ltd. All rights reserved.

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)

Anaerobic respiration of Escherichia coli in the mouse intestine.

PubMed

Jones, Shari A; Gibson, Terri; Maltby, Rosalie C; Chowdhury, Fatema Z; Stewart, Valley; Cohen, Paul S; Conway, Tyrrell

2011-10-01

The intestine is inhabited by a large microbial community consisting primarily of anaerobes and, to a lesser extent, facultative anaerobes, such as Escherichia coli, which we have shown requires aerobic respiration to compete successfully in the mouse intestine (S. A. Jones et al., Infect. Immun. 75:4891-4899, 2007). If facultative anaerobes efficiently lower oxygen availability in the intestine, then their sustained growth must also depend on anaerobic metabolism. In support of this idea, mutants lacking nitrate reductase or fumarate reductase have extreme colonization defects. Here, we further explore the role of anaerobic respiration in colonization using the streptomycin-treated mouse model. We found that respiratory electron flow is primarily via the naphthoquinones, which pass electrons to cytochrome bd oxidase and the anaerobic terminal reductases. We found that E. coli uses nitrate and fumarate in the intestine, but not nitrite, dimethyl sulfoxide, or trimethylamine N-oxide. Competitive colonizations revealed that cytochrome bd oxidase is more advantageous than nitrate reductase or fumarate reductase. Strains lacking nitrate reductase outcompeted fumarate reductase mutants once the nitrate concentration in cecal mucus reached submillimolar levels, indicating that fumarate is the more important anaerobic electron acceptor in the intestine because nitrate is limiting. Since nitrate is highest in the absence of E. coli, we conclude that E. coli is the only bacterium in the streptomycin-treated mouse large intestine that respires nitrate. Lastly, we demonstrated that a mutant lacking the NarXL regulator (activator of the NarG system), but not a mutant lacking the NarP-NarQ regulator, has a colonization defect, consistent with the advantage provided by NarG. The emerging picture is one in which gene regulation is tuned to balance expression of the terminal reductases that E. coli uses to maximize its competitiveness and achieve the highest possible population in

[Studies on anaerobic infection in oro-maxillary region--rapid diagnosis by gas-liquid chromatography and antibiotic susceptibilities of anaerobic bacteria].

PubMed

Tanaka, J I

1989-08-01

Subject material for this study was pus collected from patients with purulent inflammation in the oro-maxillary region. Direct gas-liquid chromatography (GLC) analysis was made, bacterial isolation and identification were carried out, and comparisons were made with results from GLC analysis and anaerobic isolates in a PYG medium. In addition, antibiotic susceptibilities of anaerobic bacteria were examined. Results 1. Anaerobic bacteria were isolated from 85 of 100 cases of obstructive abscesses. Of the 85, 49 were cases of mixed infection involving both anaerobic and aerobic bacteria; and 64 cases were involved with more than 2 species of anaerobic bacteria. Of the 184 strains of anaerobic isolates, 53 were Bacteroides sp. and 51 were Peptostreptococcus sp. The 2 groups accounted for more than half of the isolates. 2. Group A, in which no VFA was detected, accounted for 17 out of 100 cases. Group B, in which acetic acid was detected, accounted for 20 cases; and Group C, in which butyric acid was detected, accounted for 20 cases; and Group D, in which iso-valeric acid was detected, accounted for 8 cases. Direct GLC analysis revealed iso-caproic and caproic acids in the 35 cases constituting Group E. 3. Whereas the percentage of anaerobic bacteria was 64.7% in Group A and 60% in Group B, significantly higher percentages were noted in Group C (95%), Group D (100%) and Group E (100%). The following species were isolated as major member in the groups; Group A--Streptococcus intermedius, Group B--Peptostreptococcus micros, Group C--Fusobacterium nucleatum, Group D--Bacteroides gingivalis, and Group E--Peptostreptococcus anaerobius. 4. In all cases, the sum of VFA produced in the PYG medium by anaerobic isolates was classified into Group A' to E'. Ratios of agreement between VFA as revealed by direct GLC and VFA as revealed by PYG.GLC were as follows: Group A-A'; 47.1%, Group B-B' and C-C'; 45%, Group D-D'; 87.5%, and Group E-E'; 62.9%. 5. In Group B, no propionic acid

Assessment of the anaerobic degradation of six active pharmaceutical ingredients.

PubMed

Musson, Stephen E; Campo, Pablo; Tolaymat, Thabet; Suidan, Makram; Townsend, Timothy G

2010-04-01

Research examined the anaerobic degradation of 17 alpha-ethynylestradiol, acetaminophen, acetylsalicylic acid, ibuprofen, metoprolol tartrate, and progesterone by methanogenic bacteria. Using direct sample analysis and respirometric testing, anaerobic degradation was examined with (a) each compound as the sole organic carbon source and (b) each compound at a lower concentration (250 microg/L) and cellulose serving as the primary organic carbon source. The change in pharmaceutical concentration was determined following 7, 28, 56, and 112 days of anaerobic incubation at 37 degrees C. Only acetylsalicylic acid demonstrated significant degradation; the remaining compounds showed a mixture of degradation and abiotic removal mechanisms. Experimental results were compared with BIOWIN, an anaerobic degradation prediction model of the US Environmental Protection Agency. The BIOWIN model predicted anaerobic biodegradability of the compounds in the order: acetylsalicylic acid > metoprolol tartrate > ibuprofen > acetaminophen > 17 alpha-ethinylestradiol >progesterone. This corresponded well with the experimental findings which found degradability in the order: acetylsalicylic acid > metoprolol tartrate > acetaminophen > ibuprofen. (c) 2010 Elsevier B.V. All rights reserved.

Performance of an anaerobic membrane bioreactor for pharmaceutical wastewater treatment.

PubMed

Svojitka, Jan; Dvořák, Lukáš; Studer, Martin; Straub, Jürg Oliver; Frömelt, Heinz; Wintgens, Thomas

2017-04-01

Anaerobic treatment of wastewater and waste organic solvents originating from the pharmaceutical and chemical industries was tested in a pilot anaerobic membrane bioreactor, which was operated for 580days under different operational conditions. The goal was to test the long-term treatment efficiency and identify inhibitory factors. The highest COD removal of up to 97% was observed when the influent concentration was increased by the addition of methanol (up to 25gL -1 as COD). Varying and generally lower COD removal efficiency (around 78%) was observed when the anaerobic membrane bioreactor was operated with incoming pharmaceutical wastewater as sole carbon source. The addition of waste organic solvents (>2.5gL -1 as COD) to the influent led to low COD removal efficiency or even to the breakdown of anaerobic digestion. Changes in the anaerobic population (e.g., proliferation of the genus Methanosarcina) resulting from the composition of influent were observed. Copyright © 2017 Elsevier Ltd. All rights reserved.

Activity of a novel carbapenem, doripenem, against anaerobic pathogens.

PubMed

Goldstein, Ellie J C; Citron, Diane M

2009-04-01

Doripenem, a synthetic 1-beta-methyl carbapenem, has a broad-spectrum of activity against almost all species of anaerobic bacteria, including all Bacteroides fragilis group species, most with MIC(90) results at anaerobic intra-abdominal infections noted "noninferiority" of doripenem when compared with meropenem, but in vitro against the anaerobes, it was "more potent than meropenem, ertapenem, ... and similar to imipenem". Doripenem activity against anaerobes seems comparable with the other extant carbapenems. Although resistance among anaerobic bacteria to this agent is possible, it remains relatively rare.

Development and evaluation of the quick anaero-system-a new disposable anaerobic culture system.

PubMed

Yang, Nam Woong; Kim, Jin Man; Choi, Gwang Ju; Jang, Sook Jin

2010-04-01

We developed a new disposable anaerobic culture system, namely, the Quick anaero-system, for easy culturing of obligate anaerobes. Our system consists of 3 components: 1) new disposable anaerobic gas pack, 2) disposable culture-envelope and sealer, and 3) reusable stainless plate rack with mesh containing 10 g of palladium catalyst pellets. To evaluate the efficiency of our system, we used 12 anaerobic bacteria. We prepared 2 sets of ten-fold serial dilutions of the 12 anaerobes, and inoculated these samples on Luria-Bertani (LB) broth and LB blood agar plate (LB-BAP) (BD Diagnostic Systems, USA). Each set was incubated in the Quick anaero-system (DAS Tech, Korea) and BBL GasPak jar with BD GasPak EZ Anaerobe Container System (BD Diagnostic Systems) at 35-37 degrees C for 48 hr. The minimal inoculum size showing visible growth of 12 anaerobes when incubated in both the systems was compared. The minimal inoculum size showing visible growth for 2 out of the 12 anaerobes in the LB broth and 9 out of the 12 anaerobes on LB-BAP was lower for the Quick anaero-system than in the BD GasPak EZ Anaerobe Container System. The mean time (+/-SD) required to achieve absolute anaerobic conditions of the Quick anaero-system was 17 min and 56 sec (+/-3 min and 25 sec). The Quick anaero-system is a simple and effective method of culturing obligate anaerobes, and its performance is superior to that of the BD GasPak EZ Anaerobe Container System.

Association Between Anaerobic Metabolic Demands During Simulated Brazilian Jiu-Jitsu Combat and Specific Jiu-Jitsu Anaerobic Performance Test.

PubMed

Villar, Rodrigo; Gillis, Jason; Santana, Givanildo; Pinheiro, Daniel S; Almeida, André L R A

2018-02-01

Villar, R, Gillis, J, Santana, G, Pinheiro, DS, and Almeida, ALRA. Association between anaerobic metabolic demands during simulated Brazilian jiu-jitsu combat and specific jiu-jitsu anaerobic performance test. J Strength Cond Res 32(2): 432-440, 2018-The aims of this study were to design a specific Jiu-Jitsu anaerobic performance test (JJAPT) and investigate the relationship between blood lactate ([La]), heart rate (HR), and rating of perceived exertion (RPE) during simulated Brazilian Jiu-Jitsu combat (SBJJC) and JJAPT. Nine male elite Brazilian medium heavy weight athletes performed a 10-minute SBJJC and JJAPT that required performance of a common BJJ technique for 5 consecutive bouts of 1-minute with 45-second rest between bouts. [La] was measured by a lactate analyzer, HR by an HR monitor, and RPE using Borg's scale, and the number of repetitions of butterfly lifts (NBL) was recorded. During JJAPT, NBL decreased in the fourth and fifth bouts (p ≤ 0.05) with increases in [La], HR, and RPE (p ≤ 0.05), indicating that the JJAPT measured anaerobic performance. [La] during SBJJC was not different than [La] at the third and fourth bouts, but was significantly different than the fifth bout (p ≤ 0.05). [La] showed strong correlation between SBJJC and JJAPT for the third (r = 0.80, p ≤ 0.05), fourth (r = 0.83, p ≤ 0.05), and fifth (r = 0.82, p ≤ 0.05) bouts, but not between the HR and RPE. The JJAPT with 4 bouts presented the best combination of stimulus and highest correlation with SBJJC, supporting its use to assess anaerobic performance of BJJ athletes. These data will aid coaches and athletes to better understand the demands of their sport and may help to monitor adaptation in sport-specific performance across periodized training plans.

Preliminary report on anaerobic culture at Mymensingh Medical College Hospital in Bangladesh.

PubMed

Ahmed, S; Hossain, M A; Musa, A K; Shamsuzzaman, A K; Mahmud, M C; Nahar, K; Paul, S K; Sumona, A A; Begum, Z; Zahan, N A; Huda, S N; Ahmed, M U; Khan, A H; Kalam, A; Haque, N; Nasrin, S A

2010-01-01

Puerperal sepsis is an important cause of maternal morbidity and mortality in developing countries. This study was undertaken to isolate and identify the anaerobic bacterial agents of puerperal sepsis among the patients admitted in Mymensingh Medical College Hospital (MMCH) during the period from July 2006 to June 2007. Endocervical swabs/secretions were collected from 50 cases of puerperal sepsis and were cultured anaerobically. Anaerobiasis was done by using gas pack (BD GAS PAK TM EZ) in anaerobic jar. Out of 50 samples, 42(84%) yielded growth in cultures. Among 42 culture positive cases, 20(40%) were Aerobic organisms and 22(44%) were mixed, i.e., Aerobic and Anaerobic bacteria. The isolated Anaerobic organisms were Peptostreptococcus 14(63.63%), Bacteroides fragilis 3(13.64%), Prevotella melaninogenica 3(13.64%) and Clostridium perfringens 2(9.09%). As a preliminary study, it was observed that anaerobic culture could be carried out with available logistic arrangement. So, it was recommended to design further study on anaerobic bacterial isolation with particular emphasis on their antimicrobial susceptibility.

Potential Application of Anaerobic Extremophiles for Hydrogen Production

NASA Technical Reports Server (NTRS)

Pikuta, Elena V.; Hoover, Richard B.

2004-01-01

During substrate fermentation many anaerobes produce the hydrogen as a waste product, which often regulates the growth of the cultures as an inhibitor. In nature the hydrogen is usually removed from the ecosystem due to its physical properties or by consumption of hydrogen by secondary anaerobes, which sometimes behave as competitors for electron donors as is seen in the classical example in anaerobic microbial communities via the interaction between methanogens and sulfate- or sulfur- reducers. It was demonstrated previously on mixed cultures of anaerobes at neutral pH that bacterial hydrogen production could provide an alternative energy source. But at neutral pH the original cultures can easily be contaminated by methanogens, a most unpleasant side effect of these conditions is the development of pathogenic bacteria. In both cases the rate of hydrogen production was dramatically decreased since some part of the hydrogen was transformed to methane, and the cultivation of human pathogens on a global scale is very dangerous. In our laboratory, experiments with obligately alkaliphilic bacteria that excrete hydrogen as the end metabolic product were performed at different temperature regimes. Mesophilic and moderately thermophilic bacterial cultures have been studied and compared for the most effective hydrogen production. For high-mineralized media with pH 9.5-10.0 not many methanogens are known to exist. Furthermore, the development of pathogenic contaminant microorganisms is virtually impossible: carbonate-saturated solutions are used as antiseptics in medicine. Therefore the cultivation of alkaliphilic hydrogen producing bacteria could be considered as most safe process for global Scale industry in future. Here we present experimental data on the rates of hydrogen productivity for mesophilic, alkaliphilic, obligately anaerobic bacterium Spirocheta americana ASpG1 and moderately thermophilic, alkaliphilic, facultative anaerobe Anoxybacillus pushchinoensis K1 and

Endocarditis caused by anaerobic bacteria.

PubMed

Kestler, M; Muñoz, P; Marín, M; Goenaga, M A; Idígoras Viedma, P; de Alarcón, A; Lepe, J A; Sousa Regueiro, D; Bravo-Ferrer, J M; Pajarón, M; Costas, C; García-López, M V; Hidalgo-Tenorio, C; Moreno, M; Bouza, E

2017-10-01

Infective endocarditis (IE) caused by anaerobic bacteria is a rare and poorly characterized disease. Most data reported in the literature are from case reports [1-3]. Therefore, we assessed the situation of anaerobic IE (AIE) in Spain using the database of the Spanish Collaboration on Endocarditis (GAMES). We performed a prospective study from 2008 to 2016 in 26 Spanish centers. We included 2491 consecutive cases of definite IE (Duke criteria). Anaerobic bacteria caused 22 cases (0.9%) of definite IE. Median age was 66 years (IQR, 56-73), and 19 (86.4%) patients were men. Most patients (14 [63.6%]) had prosthetic valve IE and all episodes were left-sided: aortic valves, 12 (54.5%); and mitral valves, 8 (36.4%). The most common pathogens were Propionibacterium acnes (14 [63.6%]), Lactobacillus spp (3 [13.63%]), and Clostridium spp. (2 [9.0%]), and the infection was mainly odontogenic. Fifteen of the 22 patients (68.2%) underwent cardiac surgery. Mortality was 18.2% during admission and 5.5% after 1 year of follow-up. When patients with AIE were compared with the rest of the cohort, we found that although those with AIE had a similar age and Charlson comorbidity index, they were more likely to have community-acquired IE (86.4% vs. 60.9%, p = 0.01), have undergone cardiac surgery (68.2% vs 48.7% p = 0.06), and have had lower mortality rates during admission (18.2% vs. 27.3%). IE due to anaerobic bacteria is an uncommon disease that affects mainly prosthetic valves and frequently requires surgery. Otherwise, there are no major differences between AIE and IE caused by other microorganisms. Copyright © 2017 Elsevier Ltd. All rights reserved.

Anaerobic Metabolism: Linkages to Trace Gases and Aerobic Processes

NASA Astrophysics Data System (ADS)

Megonigal, J. P.; Hines, M. E.; Visscher, P. T.

2003-12-01

Life evolved and flourished in the absence of molecular oxygen (O2). As the O2 content of the atmosphere rose to the present level of 21% beginning about two billion years ago, anaerobic metabolism was gradually supplanted by aerobic metabolism. Anaerobic environments have persisted on Earth despite the transformation to an oxidized state because of the combined influence of water and organic matter. Molecular oxygen diffuses about 104 times more slowly through water than air, and organic matter supports a large biotic O2 demand that consumes the supply faster than it is replaced by diffusion. Such conditions exist in wetlands, rivers, estuaries, coastal marine sediments, aquifers, anoxic water columns, sewage digesters, landfills, the intestinal tracts of animals, and the rumen of herbivores. Anaerobic microsites are also embedded in oxic environments such as upland soils and marine water columns. Appreciable rates of aerobic respiration are restricted to areas that are in direct contact with air or those inhabited by organisms that produce O2.Rising atmospheric O2 reduced the global area of anaerobic habitat, but enhanced the overall rate of anaerobic metabolism (at least on an area basis) by increasing the supply of electron donors and acceptors. Organic carbon production increased dramatically, as did oxidized forms of nitrogen, manganese, iron, sulfur, and many other elements. In contemporary anaerobic ecosystems, nearly all of the reducing power is derived from photosynthesis, and most of it eventually returns to O2, the most electronegative electron acceptor that is abundant. This photosynthetically driven redox gradient has been thoroughly exploited by aerobic and anaerobic microorganisms for metabolism. The same is true of hydrothermal vents (Tunnicliffe, 1992) and some deep subsurface environments ( Chapelle et al., 2002), where thermal energy is the ultimate source of the reducing power.Although anaerobic habitats are currently a small fraction of Earth

Factors involved in anaerobic growth of Saccharomyces cerevisiae.

PubMed

Ishtar Snoek, I S; Yde Steensma, H

2007-01-01

Life in the absence of molecular oxygen requires several adaptations. Traditionally, the switch from respiratory metabolism to fermentation has attracted much attention in Saccharomyces cerevisiae, as this is the basis for the use of this yeast in the production of alcohol and in baking. It has also been clear that under anaerobic conditions the yeast is not able to synthesize sterols and unsaturated fatty acids and that for anaerobic growth these have to be added to the media. More recently it has been found that many more factors play a role. Several other biosynthetic reactions also require molecular oxygen and the yeast must have alternatives for these. In addition, the composition of the cell wall and cell membrane show major differences when aerobic and anaerobic cells are compared. All these changes are reflected by the observation that the transcription of more than 500 genes changes significantly between aerobically and anaerobically growing cultures. In this review we will give an overview of the factors that play a role in the survival in the absence of molecular oxygen. Copyright (c) 2007 John Wiley & Sons, Ltd.

An integrative perspective of the anaerobic threshold.

PubMed

Sales, Marcelo Magalhães; Sousa, Caio Victor; da Silva Aguiar, Samuel; Knechtle, Beat; Nikolaidis, Pantelis Theodoros; Alves, Polissandro Mortoza; Simões, Herbert Gustavo

2017-12-14

The concept of anaerobic threshold (AT) was introduced during the nineteen sixties. Since then, several methods to identify the anaerobic threshold (AT) have been studied and suggested as novel 'thresholds' based upon the variable used for its detection (i.e. lactate threshold, ventilatory threshold, glucose threshold). These different techniques have brought some confusion about how we should name this parameter, for instance, anaerobic threshold or the physiological measure used (i.e. lactate, ventilation). On the other hand, the modernization of scientific methods and apparatus to detect AT, as well as the body of literature formed in the past decades, could provide a more cohesive understanding over the AT and the multiple physiological systems involved. Thus, the purpose of this review was to provide an integrative perspective of the methods to determine AT. Copyright © 2017 Elsevier Inc. All rights reserved.

Anaerobic bacteria colonizing the lower airways in lung cancer patients.

PubMed

Rybojad, Pawel; Los, Renata; Sawicki, Marek; Tabarkiewicz, Jacek; Malm, Anna

2011-01-01

Anaerobes comprise most of the endogenous oropharyngeal microflora, and can cause infections of airways in lung cancer patients who are at high risk for respiratory tract infections. The aim of this study was to determine the frequency and species diversity of anaerobes in specimens from the lower airways of lung cancer patients. Sensitivity of the isolates to conventional antimicrobial agents used in anaerobe therapy was assessed. Respiratory secretions obtained by bronchoscopy from 30 lung cancer patients were cultured onto Wilkins-Chalgren agar in anaerobic conditions at 37°C for 72-96 hours. The isolates were identified using microtest Api 20A. The minimal inhibitory concentrations for penicillin G, amoxicillin/clavulanate, piperacillin/tazobactam, cefoxitin, imipenem, clindamycin, and metronidazole were determined by E-test. A total of 47 isolates of anaerobic bacteria were detected in 22 (73.3%) specimens. More than one species of anaerobe was found in 16 (53.3%) samples. The most frequently isolated were Actinomyces spp. and Peptostreptococcus spp., followed by Eubacterium lentum, Veillonella parvula, Prevotella spp., Bacteroides spp., Lactobacillus jensenii. Among antibiotics used in the study amoxicillin/clavulanate and imipenem were the most active in vitro (0% and 2% resistant strains, respectively). The highest resistance rate was found for penicillin G and metronidazole (36% and 38% resistant strains, respectively). The results obtained confirm the need to conduct analyses of anaerobic microflora colonizing the lower respiratory tract in patients with lung cancer to monitor potential etiologic factors of airways infections, as well as to propose efficient, empirical therapy.

Bioaugmentation of overloaded anaerobic digesters restores function and archaeal community.

PubMed

Tale, V P; Maki, J S; Zitomer, D H

2015-03-01

Adding beneficial microorganisms to anaerobic digesters for improved performance (i.e. bioaugmentation) has been shown to decrease recovery time after organic overload or toxicity upset. Compared to strictly anaerobic cultures, adding aerotolerant methanogenic cultures may be more practical since they exhibit higher methanogenic activity and can be easily dried and stored in ambient air for future shipping and use. In this study, anaerobic digesters were bioaugmented with both anaerobic and aerated, methanogenic propionate enrichment cultures after a transient organic overload. Digesters bioaugmented with anaerobic and moderately aerated cultures recovered 25 and 100 days before non-bioaugmented digesters, respectively. Increased methane production due to bioaugmentation continued a long time, with 50-120% increases 6 to 12 SRTs (60-120 days) after overload. In contrast to the anaerobic enrichment, the aerated enrichments were more effective as bioaugmentation cultures, resulting in faster recovery of upset digester methane and COD removal rates. Sixty days after overload, the bioaugmented digester archaeal community was not shifted, but was restored to one similar to the pre-overload community. In contrast, non-bioaugmented digester archaeal communities before and after overload were significantly different. Organisms most similar to Methanospirillum hungatei had higher relative abundance in well-operating, undisturbed and bioaugmented digesters, whereas organisms similar to Methanolinea tarda were more abundant in upset, non-bioaugmented digesters. Bioaugmentation is a beneficial approach to increase digester recovery rate after transient organic overload events. Moderately aerated, methanogenic propionate enrichment cultures were more beneficial augments than a strictly anaerobic enrichment. Copyright © 2014 Elsevier Ltd. All rights reserved.

A field test for determining the speed obtained through anaerobic glycolysis in runners.

PubMed

Borsetto, C; Ballarin, E; Casoni, I; Cellini, M; Vitiello, P; Conconi, F

1989-10-01

A field test for the evaluation of the speed generated by the anaerobic lactacid mechanism has been developed in runners. The test consists of 1200 m of continuous running: in the first 1000 m the speed corresponding to the anaerobic threshold is progressively reached; in the last 200 m an all-out sprint is performed. The speed at the anaerobic threshold is subtracted from the speed reached in the final 200-m all-out sprint. In 39 runners examined (marathon runners, n = 13; 5000-10000-m runners, n = 10; 400-800-m runners, n = 7; sprinters, n = 9), the additional speed generated above the anaerobic threshold was correlated with the venous blood lactate concentration reached 5 min after the all-out effort (r = 0.93). The anaerobic speeds measured by the test were in keeping with the characteristics of the runners under study, i.e., anaerobic speeds were highest for the sprinters, intermediate for the middle-distance runners, and lowest for the marathon runners. Since the speed generated above the anaerobic threshold by the aerobic fuel breakdown can be subtracted, the contribution of creatine phosphate is minimal, and the speed exceeding the anaerobic threshold is highly correlated with lactate accumulation, the present test should measure the speed generated by anaerobic glycolysis.

Effects of sludge recirculation rate and mixing time on performance of a prototype single-stage anaerobic digester for conversion of food wastes to biogas and energy recovery.

PubMed

Ratanatamskul, Chavalit; Saleart, Tawinan

2016-04-01

Food wastes have been recognized as the largest waste stream and accounts for 39.25 % of total municipal solid waste in Thailand. Chulalongkorn University has participated in the program of in situ energy recovery from food wastes under the Ministry of Energy (MOE), Thailand. This research aims to develop a prototype single-stage anaerobic digestion system for biogas production and energy recovery from food wastes inside Chulalongkorn University. Here, the effects of sludge recirculation rate and mixing time were investigated as the main key parameters for the system design and operation. From the results obtained in this study, it was found that the sludge recirculation rate of 100 % and the mixing time of 60 min per day were the most suitable design parameters to achieve high efficiencies in terms of chemical oxygen demand (COD), total solids (TS), and total volatile solid (TVS) removal and also biogas production by this prototype anaerobic digester. The obtained biogas production was found to be 0.71 m(3)/kg COD and the composition of methane was 61.6 %. Moreover, the efficiencies of COD removal were as high as 82.9 % and TVS removal could reach 83.9 % at the optimal condition. Therefore, the developed prototype single-stage anaerobic digester can be highly promising for university canteen application to recover energy from food wastes via biogas production.

Reducing the environmental impact of methane emissions from dairy farms by anaerobic digestion of cattle waste.

PubMed

Marañón, E; Salter, A M; Castrillón, L; Heaven, S; Fernández-Nava, Y

2011-08-01

Four dairy cattle farms considered representative of Northern Spain milk production were studied. Cattle waste was characterised and energy consumption in the farms was inventoried. Methane emissions due to slurry/manure management and fuel consumption on the farms were calculated. The possibility of applying anaerobic digestion to the slurry to minimise emissions and of using the biogas produced to replace fossil fuels on the farm was considered. Methane emissions due to slurry management (storage and use as fertiliser) ranged from 34 to 66kg CH(4)cow(-1)year(-1) for dairy cows and from 13 to 25kg CH(4)cow(-1)year(-1) for suckler calves. Cattle on these farms are housed for most of the year, and the contribution from emissions from manure dropped in pastures is insignificant due to the very low methane conversion factors. If anaerobic digestion were implemented on the farms, the potential GHG emissions savings per livestock unit would range from 978 to 1776kg CO(2)eq year(-1), with the main savings due to avoided methane emissions during slurry management. The methane produced would be sufficient to supply digester heating needs (35-55% of the total methane produced) and on-farm fuel energy requirements. Copyright © 2011 Elsevier Ltd. All rights reserved.

Sustainable nitrogen removal by denitrifying anammox applied for anaerobic pre-treated potato wastewater.

PubMed

Mulder, A; Versprille, A I; van Braak, D

2012-01-01

The feasibility of sustainable nitrogen removal was investigated in a two stage biofilm configuration consisting of a MBBR (Moving Bed Biofilm Reactor) and a Deamox reactor (Biobed-EGSB). The MBBR is used for nitrification and the denitrifying ammonium oxidation (Deamox) is aimed at a nitrogen removal process in which part of the required nitrite for the typical anammox reaction originated from nitrate. Anaerobic pre-treated potato wastewater was supplied to a MBBR and Deamox reactor operated in series with a bypass flow of 30%. The MBBR showed stable nitrite production at ammonium-loading rates of 0.9-1.0 kg NH₄-N/m³ d with ammonium conversion rates of 0.80-0.85 kg NH₄-N/m³ d. The nitrogen-loading rate and conversion rate of the Deamox reactor were 1.6-1.8 and 1.6 kg N/m³ d. The maximum ammonium removal capacity in the Deamox reactor was 0.6 kg NH₄-N/m³ d. The removal efficiency of soluble total nitrogen reached 90%. The Deamox process performance was found to be negatively affected during decline of the operating temperature from 33 to 22 °C and by organic loading rates with a chemical oxygen demand (COD)/NO₂-N ratio >1.

Linking pyrolysis and anaerobic digestion (Py-AD) for the conversion of lignocellulosic biomass.

PubMed

Fabbri, Daniele; Torri, Cristian

2016-04-01

Biogas is a mixture of CO2 and CH4 produced by a consortia of Bacteria and Archeae operating in anaerobic digestion (AD) plants. Biogas can be burnt as such in engines to produce electricity and heat or upgraded into biomethane. Biomethane is a drop-in fuel that can be injected in the natural gas grid or utilised as a transport fuel. While a wide array of biomass feedstock can be degraded into biogas, unconverted lignin, hemicellulose and cellulose end up in the co-product digestate leaving a large portion of chemical energy unutilised. Pyrolysis (Py) transforms in a single step and without chemical reagents the lignocellulose matrix into gaseous (syngas), liquid (bio-oil, pyrolysis oil) and solid (biochar) fractions for the development of renewable fuels and materials. The Py route applied downstream to AD is actively investigated in order to valorise the solid digestate presently destined only for soil applications. Coupling Py upstream to AD is an emerging field of research aimed at expanding the feedstock towards biologically recalcitrant substrates (wood, paper, sludge). The biomethanation potential was demonstrated for gaseous (H2/CO) and water soluble pyrolysis products, while the influence of insoluble pyrolytic lignin remains fairly unexplored. Biochar can promote the production of biomethane by acting as a support for microorganism colonisation, conductor for direct interspecies electron transfer, sorbent for hydrophobic inhibitors, and reactant for in situ biogas upgrading. Enhancing the advantages (carbon source) over the side effects (toxicity) of Py fractions represents the main challenge of Py-AD. This can be addressed by increasing the selectivity of the thermochemical process or improving the ecological flexibility of mixed bacterial consortia towards chemically complex environments. Copyright © 2016 Elsevier Ltd. All rights reserved.

Anaerobic rumen SBR for degradation of cellulosic material.

PubMed

Barnes, S P; Keller, J

2004-01-01

Hydrolysis of organic particulates under anaerobic conditions is generally regarded as the rate limiting step in solid digestion processes. Rumen-based ecosystems appear to achieve very high hydrolysis rates for cellulosic organic material. This study aimed at the development and demonstration of an anaerobic sequencing batch reactor (SBR) process operating with a rumen-based microbial inoculum. Fibrous alpha cellulose was used as sole carbon substrate and the use of an SBR operating cycle allowed the utilisation of a high liquid flow rate (hydraulic retention time of 0.67 d) while maintaining a much longer solids retention time of 7 d. Complete mass balances for carbon and nitrogen, as well as COD balancing allowed the full characterisation of the process stoichiometry and kinetics. Elemental analysis of the biomass revealed a composition of C5H4.8O2.4N0.7, which is quite different from other generic biomass compositions used in the literature. The anaerobic rumen SBR was compared with another rumen-based reactor system in the literature which used a continuous filtration process for solid/liquid separation. This comparison showed that the volatile fatty acid production rate from cellulose in the anaerobic SBR was comparable with the performance achieved in the continuous system, although loading, substrate type and media composition were quite different between these two studies. Further evaluation of the anaerobic rumen SBR is required to determine its practical application for other substrates and to demonstrate the scale-up potential of this concept.

Bacterial ecology of abattoir wastewater treated by an anaerobic digestor

PubMed Central

Jabari, Linda; Gannoun, Hana; Khelifi, Eltaief; Cayol, Jean-Luc; Godon, Jean-Jacques; Hamdi, Moktar; Fardeau, Marie-Laure

2016-01-01

Wastewater from an anaerobic treatment plant at a slaughterhouse was analysed to determine the bacterial biodiversity present. Molecular analysis of the anaerobic sludge obtained from the treatment plant showed significant diversity, as 27 different phyla were identified. Firmicutes, Proteobacteria, Bacteroidetes, Thermotogae, Euryarchaeota (methanogens), and msbl6 (candidate division) were the dominant phyla of the anaerobic treatment plant and represented 21.7%, 18.5%, 11.5%, 9.4%, 8.9%, and 8.8% of the total bacteria identified, respectively. The dominant bacteria isolated were Clostridium, Bacteroides, Desulfobulbus, Desulfomicrobium, Desulfovibrio and Desulfotomaculum. Our results revealed the presence of new species, genera and families of microorganisms. The most interesting strains were characterised. Three new bacteria involved in anaerobic digestion of abattoir wastewater were published. PMID:26887229

Aged refuse enhances anaerobic digestion of waste activated sludge.

PubMed

Zhao, Jianwei; Gui, Lin; Wang, Qilin; Liu, Yiwen; Wang, Dongbo; Ni, Bing-Jie; Li, Xiaoming; Xu, Rui; Zeng, Guangming; Yang, Qi

2017-10-15

In this work, a low-cost alternative approach (i.e., adding aged refuse (AR) into waste activated sludge) to significantly enhance anaerobic digestion of sludge was reported. Experimental results showed that with the addition dosage of AR increasing from 0 to 400 mg/g dry sludge soluble chemical oxygen demand (COD) increased from 1150 to 5240 mg/L at the digestion time of 5 d, while the maximal production of volatile fatty acids (VFA) increased from 82.6 to 183.9 mg COD/g volatile suspended solids. Although further increase of AR addition decreased the concentrations of both soluble COD and VFA, their contents in these systems with AR addition at any concentration investigated were still higher than those in the blank, which resulted in higher methane yields in these systems. Mechanism studies revealed that pertinent addition of AR promoted solubilization, hydrolysis, and acidogenesis processes and did not affect methanogenesis significantly. It was found that varieties of enzymes and anaerobes in AR were primary reason for the enhancement of anaerobic digestion. Humic substances in AR benefited hydrolysis and acidogenesis but inhibited methanogenesis. The effect of heavy metals in AR on sludge anaerobic digestion was dosage dependent. Sludge anaerobic digestion was enhanced by appropriate amounts of heavy metals but inhibited by excessive amounts of heavy metals. The relative abundances of microorganisms responsible for sludge hydrolysis and acidogenesis were also observed to be improved in the system with AR addition, which was consistent with the performance of anaerobic digestion. Copyright © 2017 Elsevier Ltd. All rights reserved.

Anaerobic Carbon Metabolism by the Tricarboxylic Acid Cycle 1

PubMed Central

Vanlerberghe, Greg C.; Horsey, Anne K.; Weger, Harold G.; Turpin, David H.

1989-01-01

Nitrogen-limited cells of Selenastrum minutum (Naeg.) Collins are able to assimilate NH4+ in the dark under anaerobic conditions. Addition of NH4+ to anaerobic cells results in a threefold increase in tricarboxylic acid cycle (TCAC) CO2 efflux and an eightfold increase in the rate of anaplerotic carbon fixation via phosphoenolpyruvate carboxylase. Both of these observations are consistent with increased TCAC carbon flow to supply intermediates for amino acid biosynthesis. Addition of H14CO3− to anaerobic cells assimilating NH4+ results in the incorporation of radiolabel into the α-carboxyl carbon of glutamic acid. Incorporation of radiolabel into glutamic acid is not simply a short-term phenomenon following NH4+ addition as the specific activity of glutamic acid increases over time. This indicates that this alga is able to maintain partial oxidative TCAC carbon flow while under anoxia to supply α-ketoglutarate for glutamate production. During dark aerobic NH4+ assimilation, no radiolabel appears in fumarate or succinate and only a small amount occurs in malate. During anaerobic NH4+ assimilation, these metabolites contain a large proportion of the total radiolabel and radiolabel accumulates in succinate over time. Also, the ratio of dark carbon fixation to NH4+ assimilation is much higher under anaerobic than aerobic conditions. These observations suggest the operation of a partial reductive TCAC from oxaloacetic acid to malate, fumarate, and succinate. Such a pathway might contribute to redox balance in an anaerobic cell maintaining partial oxidative TCAC activity. PMID:16667215

Recurrence of fecal coliforms and Salmonella species in biosolids following thermophilic anaerobic digestion.

PubMed

Iranpour, Reza; Cox, Huub H J

2006-09-01

The U.S. Environmental Protection Agency (U.S. EPA) Part 503 Biosolids Rule requires the fecal coliform (indicator) or Salmonella species (pathogen) density requirements for Class A biosolids to be met at the last point of plant control (truck-loading facility and/or farm for land application). The three Southern Californian wastewater treatment plants in this study produced biosolids by thermophilic anaerobic digestion and all met the Class A limits for both fecal coliforms and Salmonella sp. in the digester outflow biosolids. At two plants, however, a recurrence of fecal coliforms was observed in postdigestion biosolids, which caused exceedance of the Class A limit for fecal coliforms at the truck-loading facility and farm for land application. Comparison of observations at the three plants and further laboratory tests indicated that the recurrence of fecal coliforms can possibly be related to the following combination of factors: (1) incomplete destruction of fecal coliforms during thermophilic anaerobic digestion, (2) contamination of Class A biosolids with fecal coliforms from external sources during postdigestion, (3) a large drop of the postdigestion biosolids temperature to below the maximum for fecal coliform growth, (4) an unknown effect of biosolids dewatering in centrifuges. At Hyperion Treatment Plant (City of Los Angeles, California), fecal coliform recurrence could be prevented by the following: (1) complete conversion to thermophilic operation to exclude contamination by mesophilically digested biosolids and (2) insulation and electrical heat-tracing of postdigestion train for maintaining a high biosolids temperature in postdigestion.

Anaerobic antibiotic usage for pneumonia in the medical intensive care unit.

PubMed

Kioka, Mutsumi J; DiGiovine, Bruno; Rezik, Mohamed; Jennings, Jeffrey H

2017-11-01

Pneumonia is a common admitting diagnosis in the intensive care unit (ICU). When aspiration is suspected, antibiotics to cover anaerobes are frequently used, but in the absence of clear risk factors, current guidelines have questioned their role. It is unknown how frequently these guidelines are followed. We conducted a single-centre observational study on practice patterns of anaerobic antibiotic use in consecutive patients admitted to the ICU with aspiration pneumonia (Asp), community-acquired pneumonia (CAP) and healthcare-associated pneumonia (HCAP). A total of 192 patients were studied (Asp: 20, HCAP: 107, CAP: 65). Overall, 59 patients received anaerobic antibiotics (Asp: 90%, HCAP: 28%, CAP 17%) but a significant proportion of these patients did not meet criteria to receive them. Inappropriate anaerobic antibiotic use was 12/20 for Asp, 27/107 for HCAP and 9/65 for CAP. Mortality probability model III at zero hours (MPM0) score and a diagnosis of Asp were predictors of receiving inappropriate anaerobic antibiotics. Receiving inappropriate anaerobic antibiotics was associated with a longer ICU length of stay (LOS; 7 days (interquartile range (IQR): 7-21) vs 4 days (IQR:2-9), P = 0.017). For patients in the ICU admitted with pneumonia, there is a high occurrence of inappropriately prescribed anaerobic antibiotics, the use of which was associated with a longer ICU LOS. © 2017 Asian Pacific Society of Respirology.

Amixicile, a novel strategy for targeting oral anaerobic pathogens.

PubMed

Hutcherson, Justin A; Sinclair, Kathryn M; Belvin, Benjamin R; Gui, Qin; Hoffman, Paul S; Lewis, Janina P

2017-09-05

The oral microflora is composed of both health-promoting as well as disease-initiating bacteria. Many of the disease-initiating bacteria are anaerobic and include organisms such as Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum, and Tannerella forsythia. Here we investigated a novel therapeutic, amixicile, that targets pyruvate:ferredoxin oxidoreductase (PFOR), a major metabolic enzyme involved in energy generation through oxidative decarboxylation of pyruvate. PFOR is present in these anaerobic pathogenic bacteria and thus we hypothesized that amixicile would effectively inhibit their growth. In general, PFOR is present in all obligate anaerobic bacteria, while oral commensal aerobes, including aerotolerant ones, such as Streptococcus gordonii, use pyruvate dehydrogenase to decarboxylate pyruvate. Accordingly, we observed that growth of the PFOR-containing anaerobic periodontal pathogens, grown in both monospecies as well as multispecies broth cultures was inhibited in a dose-dependent manner while that of S. gordonii was unaffected. Furthermore, we also show that amixicile is effective against these pathogens grown as monospecies and multispecies biofilms. Finally, amixicile is the first selective therapeutic agent active against bacteria internalized by host cells. Together, the results show that amixicile is an effective inhibitor of oral anaerobic bacteria and as such, is a good candidate for treatment of periodontal diseases.

Enzymes catalyzing pre-hydrolysis facilitated the anaerobic fermentation of waste activated sludge with acidogenic and microbiological perspectives.

PubMed

Xin, Xiaodong; He, Junguo; Li, Lin; Qiu, Wei

2018-02-01

This study investigated acidogenic and microbiological perspectives in the anaerobic fermentation (AF) of waste activated sludge (WAS) pre-hydrolyzed by enzymes catalysis. The enzymes catalysis boosted WAS biodegradability dramatically with nearly 8500 mg/L soluble chemical oxygen demand (SCOD) increase just within 4 h. The volatile fatty acids (VFAs) in the acidogenesis were accumulated effectively with over 3200 mg COD/L in 12 d, which reached 0.687 kWh/kg VSS electricity conversion efficiency (2.5 times higher than the control test). The fermentation process favored the compression of fermentative sludge with the distribution spread index (DSI) rising. The core populations of bacteria and archaea shifting enlarged the dissimilarity of communities at different fermentation stages. Increase of community diversity contributed to VFAs accumulation stability. Moreover, the intermediate bacterial community evenness favored VFAs accumulation potentially. The enzymes catalysis might be a promising solution for strengthening VFAs accumulation in the WAS fermentation with boosting the electricity conversion potential. Copyright © 2017 Elsevier Ltd. All rights reserved.

Induction of oxidative DNA damage in anaerobes.

PubMed

Takeuchi, T; Nakaya, Y; Kato, N; Watanabe, K; Morimoto, K

1999-05-07

We compared oxidative DNA damage in strictly anaerobic Prevotella melaninogenica, aerotolerant anaerobic Bacteroides fragilis, and facultative anaerobic Salmonella typhimurium after exposure to O2 or H2O2. Using HPLC with electrochemical detection, we measured 8-hydroxydeoxyguanosine (8OHdG) as a damage marker. O2 induced 8OHdG in P. melaninogenica but not in B. fragilis, which shows catalase activity, or in S. typhimurium. In P. melaninogenica, with catalase, O2 induced less 8OHdG; superoxide dismutase had no effect; with glucose and glucose oxidase, O2 induced more 8OHdG. H2O2 also markedly increased 8OHdG. O2 was suggested to induce 8OHdG through H2O2. O2 or H2O2 decreased survival only in P. melaninogenica. Highly sensitive to oxidative stress, P. melaninogenica could prove useful for investigating oxidative DNA damage.

[First Argentine consensus guidelines for in vitro antimicrobial susceptibility testing of clinically relevant anaerobic bacteria in humans/ Anaerobic Subcommittee of the Asociación Argentina de Microbiología].

PubMed

Legaria, María C; Bianchini, Hebe M; Castello, Liliana; Carloni, Graciela; Di Martino, Ana; Fernández Canigia, Liliana; Litterio, Mirta; Rollet, Raquel; Rossetti, Adelaida; Predari, Silvia C

2011-01-01

Through time, anaerobic bacteria have shown good susceptibility to clinically useful antianaerobic agents. Nevertheless, the antimicrobial resistance profile of most of the anaerobic species related to severe infections in humans has been modified in the last years and different kinds of resistance to the most active agents have emerged, making their effectiveness less predictable. With the aim of finding an answer and for the purpose of facilitating the detection of anaerobic antimicrobial resistance, the Anaerobic Subcommittee of the Asociación Argentina de Microbiología developed the First Argentine consensus guidelines for in vitro antimicrobial susceptibility testing of clinically relevant anaerobic bacteria in humans. This document resulted from the compatibilization of the Clinical and Laboratory Standards Institute recommendations, the international literature and the work and experience of the Subcommittee. The Consensus document provides a brief taxonomy review, and exposes why and when anaerobic antimicrobial susceptibility tests should be conducted, and which antimicrobial agents can be used according to the species involved. The recommendations on how to perform, read and interpret in vitro anaerobic antimicrobial susceptibility tests with each method are exposed. Finally, the antibiotic susceptibility profile, the classification of antibiotics according to their in vitro activities, the natural and acquired mechanisms of resistance, the emerging resistance and the regional antibiotic resistance profile of clinically relevant anaerobic species are shown.

Anaerobic treatability of wastewater contaminated with propylene glycol.

PubMed

Sezgin, Naim; Tonuk, Gulseven Ubay

2013-09-01

The purpose of this study was to investigate the biodegradability of propylene glycol in anaerobic conditions by using methanogenic culture. A master reactor was set up to develop a culture that would be acclimated to propylene glycol. After reaching steady-state, culture was transferred to serum bottles. Three reactors with same initial conditions were run for consistency. Propylene glycol was completely biodegradable under anaerobic methanogenic conditions. Semi-continuous reactors operated at a temperature of 35°C had consistently achieved a propylene glycol removal of higher than 95 % based on chemical oxygen demand (COD). It was found that in semi-continuous reactors, anaerobic treatment of propylene glycol at concentrations higher than 1,500 mg COD m(-3) day(-1) was not convenient due to instable effluent COD.

Anaerobic orbital cellulitis: a clinical and experimental study.

PubMed Central

Jedrzynski, M S; Bullock, J D; McGuire, T W; Elder, B L; Bullock, J D

1991-01-01

In this article we have reviewed the clinical and bacteriologic aspects of anaerobic orbital cellulitis and have presented six patients to illustrate these points. Physicians who treat patients with orbital cellulitis should have a high index of suspicion for possible instances involving anaerobes, so that appropriate management can be started early. To investigate this problem further, we created an animal model of anaerobic orbital cellulitis. This model may be useful in future studies of the pathogenesis and treatment of this serious and often devastating disease. Images FIGURE 1 FIGURE 2 FIGURE 3 FIGURE 4 FIGURE 5 FIGURE 6 FIGURE 7 FIGURE 8 FIGURE 9 FIGURE 10 FIGURE 11 FIGURE 12 FIGURE 13 FIGURE 14 FIGURE 15 FIGURE 16 FIGURE 17 FIGURE 18 FIGURE 19 PMID:1808813

Redesigning Escherichia coli Metabolism for Anaerobic Production of Isobutanol▿†

PubMed Central

Trinh, Cong T.; Li, Johnny; Blanch, Harvey W.; Clark, Douglas S.

2011-01-01

Fermentation enables the production of reduced metabolites, such as the biofuels ethanol and butanol, from fermentable sugars. This work demonstrates a general approach for designing and constructing a production host that uses a heterologous pathway as an obligately fermentative pathway to produce reduced metabolites, specifically, the biofuel isobutanol. Elementary mode analysis was applied to design an Escherichia coli strain optimized for isobutanol production under strictly anaerobic conditions. The central metabolism of E. coli was decomposed into 38,219 functional, unique, and elementary modes (EMs). The model predictions revealed that during anaerobic growth E. coli cannot produce isobutanol as the sole fermentative product. By deleting 7 chromosomal genes, the total 38,219 EMs were constrained to 12 EMs, 6 of which can produce high yields of isobutanol in a range from 0.29 to 0.41 g isobutanol/g glucose under anaerobic conditions. The remaining 6 EMs rely primarily on the pyruvate dehydrogenase enzyme complex (PDHC) and are typically inhibited under anaerobic conditions. The redesigned E. coli strain was constrained to employ the anaerobic isobutanol pathways through deletion of 7 chromosomal genes, addition of 2 heterologous genes, and overexpression of 5 genes. Here we present the design, construction, and characterization of an isobutanol-producing E. coli strain to illustrate the approach. The model predictions are evaluated in relation to experimental data and strategies proposed to improve anaerobic isobutanol production. We also show that the endogenous alcohol/aldehyde dehydrogenase AdhE is the key enzyme responsible for the production of isobutanol and ethanol under anaerobic conditions. The glycolytic flux can be controlled to regulate the ratio of isobutanol to ethanol production. PMID:21642415

Anaerobic decomposition of humic substances by Clostridium from the deep subsurface

PubMed Central

Ueno, Akio; Shimizu, Satoru; Tamamura, Shuji; Okuyama, Hidetoshi; Naganuma, Takeshi; Kaneko, Katsuhiko

2016-01-01

Decomposition of humic substances (HSs) is a slow and cryptic but non-negligible component of carbon cycling in sediments. Aerobic decomposition of HSs by microorganisms in the surface environment has been well documented; however, the mechanism of anaerobic microbial decomposition of HSs is not completely understood. Moreover, no microorganisms capable of anaerobic decomposition of HSs have been isolated. Here, we report the anaerobic decomposition of humic acids (HAs) by the anaerobic bacterium Clostridium sp. HSAI-1 isolated from the deep terrestrial subsurface. The use of 14C-labelled polycatechol as an HA analogue demonstrated that the bacterium decomposed this substance up to 7.4% over 14 days. The decomposition of commercial and natural HAs by the bacterium yielded lower molecular mass fractions, as determined using high-performance size-exclusion chromatography. Fourier transform infrared spectroscopy revealed the removal of carboxyl groups and polysaccharide-related substances, as well as the generation of aliphatic components, amide and aromatic groups. Therefore, our results suggest that Clostridium sp. HSAI-1 anaerobically decomposes and transforms HSs. This study improves our understanding of the anaerobic decomposition of HSs in the hidden carbon cycling in the Earth’s subsurface. PMID:26743007

Modulation of anaerobic energy metabolism of Bacillus subtilis by arfM (ywiD).

PubMed

Marino, M; Ramos, H C; Hoffmann, T; Glaser, P; Jahn, D

2001-12-01

Bacillus subtilis grows under anaerobic conditions utilizing nitrate ammonification and various fermentative processes. The two-component regulatory system ResDE and the redox regulator Fnr are the currently known parts of the regulatory system for anaerobic adaptation. Mutation of the open reading frame ywiD located upstream of the respiratory nitrate reductase operon narGHJI resulted in elimination of the contribution of nitrite dissimilation to anaerobic nitrate respiratory growth. Significantly reduced nitrite reductase (NasDE) activity was detected, while respiratory nitrate reductase activity was unchanged. Anaerobic induction of nasDE expression was found to be significantly dependent on intact ywiD, while anaerobic narGHJI expression was ywiD independent. Anaerobic transcription of hmp, encoding a flavohemoglobin-like protein, and of the fermentative operons lctEP and alsSD, responsible for lactate and acetoin formation, was partially dependent on ywiD. Expression of pta, encoding phosphotransacetylase involved in fermentative acetate formation, was not influenced by ywiD. Transcription of the ywiD gene was anaerobically induced by the redox regulator Fnr via the conserved Fnr-box (TGTGA-6N-TCACT) centered 40.5 bp upstream of the transcriptional start site. Anaerobic induction of ywiD by resDE was found to be indirect via resDE-dependent activation of fnr. The ywiD gene is subject to autorepression and nitrite repression. These results suggest a ResDE --> Fnr --> YwiD regulatory cascade for the modulation of genes involved in the anaerobic metabolism of B. subtilis. Therefore, ywiD was renamed arfM for anaerobic respiration and fermentation modulator.

Methods of ammonia removal in anaerobic digestion: a review.

PubMed

Krakat, Niclas; Demirel, Burak; Anjum, Reshma; Dietz, Donna

2017-10-01

The anaerobic digestion of substrates with high ammonia content has always been a bottleneck in the methanisation process of biomasses. Since microbial communities in anaerobic digesters are sensitive to free ammonia at certain conditions, the digestion of nitrogen-rich substrates such as livestock wastes may result in inhibition/toxicity eventually leading to process failures, unless appropriate engineering precautions are taken. There are many different options reported in literature to remove ammonia from anaerobic digesters to achieve a safe and stable process so that along with high methane yields, a good quality of effluents can also be obtained. Conventional techniques to remove ammonia include physical/chemical methods, immobilization and adaptation of microorganisms, while novel methods include ultrasonication, microwave, hollow fiber membranes and microbial fuel cell applications. This paper discusses conventional and novel methods of ammonia removal from anaerobic digesters using nitrogen-rich substrates, with particular focus on recent literature available about this topic.

Characteristics, Process Parameters, and Inner Components of Anaerobic Bioreactors

PubMed Central

Abdelgadir, Awad; Chen, Xiaoguang; Liu, Jianshe; Xie, Xuehui; Zhang, Jian; Zhang, Kai; Wang, Heng; Liu, Na

2014-01-01

The anaerobic bioreactor applies the principles of biotechnology and microbiology, and nowadays it has been used widely in the wastewater treatment plants due to their high efficiency, low energy use, and green energy generation. Advantages and disadvantages of anaerobic process were shown, and three main characteristics of anaerobic bioreactor (AB), namely, inhomogeneous system, time instability, and space instability were also discussed in this work. For high efficiency of wastewater treatment, the process parameters of anaerobic digestion, such as temperature, pH, Hydraulic retention time (HRT), Organic Loading Rate (OLR), and sludge retention time (SRT) were introduced to take into account the optimum conditions for living, growth, and multiplication of bacteria. The inner components, which can improve SRT, and even enhance mass transfer, were also explained and have been divided into transverse inner components, longitudinal inner components, and biofilm-packing material. At last, the newly developed special inner components were discussed and found more efficient and productive. PMID:24672798

Characteristics, process parameters, and inner components of anaerobic bioreactors.

PubMed

Abdelgadir, Awad; Chen, Xiaoguang; Liu, Jianshe; Xie, Xuehui; Zhang, Jian; Zhang, Kai; Wang, Heng; Liu, Na

2014-01-01

The anaerobic bioreactor applies the principles of biotechnology and microbiology, and nowadays it has been used widely in the wastewater treatment plants due to their high efficiency, low energy use, and green energy generation. Advantages and disadvantages of anaerobic process were shown, and three main characteristics of anaerobic bioreactor (AB), namely, inhomogeneous system, time instability, and space instability were also discussed in this work. For high efficiency of wastewater treatment, the process parameters of anaerobic digestion, such as temperature, pH, Hydraulic retention time (HRT), Organic Loading Rate (OLR), and sludge retention time (SRT) were introduced to take into account the optimum conditions for living, growth, and multiplication of bacteria. The inner components, which can improve SRT, and even enhance mass transfer, were also explained and have been divided into transverse inner components, longitudinal inner components, and biofilm-packing material. At last, the newly developed special inner components were discussed and found more efficient and productive.

Enhancement of anaerobic sludge digestion by high-pressure homogenization.

PubMed

Zhang, Sheng; Zhang, Panyue; Zhang, Guangming; Fan, Jie; Zhang, Yuxuan

2012-08-01

To improve anaerobic sludge digestion efficiency, the effects of high-pressure homogenization (HPH) conditions on the anaerobic sludge digestion were investigated. The VS and TCOD were significantly removed with the anaerobic digestion, and the VS removal and TCOD removal increased with increasing the homogenization pressure and homogenization cycle number; correspondingly, the accumulative biogas production also increased with increasing the homogenization pressure and homogenization cycle number. The optimal homogenization pressure was 50 MPa for one homogenization cycle and 40 MPa for two homogenization cycles. The SCOD of the sludge supernatant significantly increased with increasing the homogenization pressure and homogenization cycle number due to the sludge disintegration. The relationship between the biogas production and the sludge disintegration showed that the accumulative biogas and methane production were mainly enhanced by the sludge disintegration, which accelerated the anaerobic digestion process and improved the methane content in the biogas. Copyright © 2012 Elsevier Ltd. All rights reserved.

Influence of thermal hydrolysis-anaerobic digestion treatment of wastewater solids on concentrations of triclosan, triclocarban, and their transformation products in biosolids.

PubMed

Armstrong, Dana L; Rice, Clifford P; Ramirez, Mark; Torrents, Alba

2017-03-01

The growing concern worldwide regarding the presence of emerging contaminants in biosolids calls for a better understanding of how different treatment technologies at water resource recovery facilities (WRRFs) can influence concentrations prior to biosolids land application. This study focuses on the influence of solids treatment via the Cambi Thermal Hydrolysis Process™ in conjunction with anaerobic digestion (TH-AD) on concentrations of triclosan (TCS), triclocarban (TCC), and their transformation products in biosolids and sludges. Concentrations of the target analytes in biosolids from the TH-AD process (Class A), sludges from the individual TH-AD treatment steps, and limed biosolids (Class B) from the same WRRF were compared. TCC concentrations were significantly lower in Class A biosolids than those in the Class B product - a removal that occurred during thermal hydrolysis. Concentrations of TCS, methyl triclosan, and 2,4-dichlorophenol, conversely, increased during anaerobic digestion, leading to significantly higher concentrations of these compounds in Class A biosolids when compared to Class B biosolids. Implementation of the TH-AD process had mixed effect on contaminant concentrations. Copyright © 2016 Elsevier Ltd. All rights reserved.

Clinico-microbiological Profile of Septic Diabetic Foot with Special Reference to Anaerobic Infection.

PubMed

Sasikumar, K; Vijayakumar, Chellappa; Jagdish, Sadasivan; Kadambari, Dharanipragada; Raj Kumar, Nagarajan; Biswas, Rakhi; Parija, Subhash Chandra

2018-03-01

Introduction Diabetic foot infections are a major cause of non-traumatic amputations. The role of anaerobes in the prognosis of these infections is particularly unclear. This study was conducted with the aim of correlating microbiological profiles with clinical outcomes in these diabetic foot ulcer patients. Methodology This prospective observational study was done in a tertiary care centre in South India. All patients admitted with diabetic foot ulcers for two years were included in the study. Tissue biopsies were collected from the ulcer for aerobic and anaerobic cultures. The patients were grouped as those with aerobic infection alone (anaerobe negative) and those with mixed aerobic and anaerobic infections (anaerobe positive). Anaerobic culture was performed using the Robertson cooked meat (RCM) medium. The ulcer of the foot was described with respect to site, size, duration, history of previous amputation(s), and history of number and class of antibiotic intake prior to hospitalization. Clinical course and Wagner's grades of the diabetic foot ulcers were compared for aerobic and anaerobic infections. Results A total of 104 patients were included in the study. There were no significant differences between the two groups with regards to duration of diabetes, random blood sugar (RBS) at the time of admission, compliance to drugs, and mode of blood sugar control and prior intake of antibiotics. Patients with anaerobic infections were found to have a higher incidence of fever in this study (38.1% vs. 14.5%; p = 0.0057), as compared to patients with aerobic infections. More than half of the patients in the anaerobic infection group presented with Wagner's grade IV and above, as compared to the aerobic infection group (59.5% vs. 32.2%; p = 0.0059), which was statistically significant. Patients with anaerobic infections also had high numbers of major and minor amputations when compared to patients with aerobic infections. Conclusion Septic diabetic foot patients with

40 CFR Table Jj-6 to Subpart Jj of... - Collection Efficiencies of Anaerobic Digesters

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 21 2011-07-01 2011-07-01 false Collection Efficiencies of Anaerobic..., Table JJ-6 Table JJ-6 to Subpart JJ of Part 98—Collection Efficiencies of Anaerobic Digesters Anaerobic digester type Cover type Methane collection efficiency Covered anaerobic lagoon (biogas capture) Bank to...

A Review of Anaerobic Infections of the Oral Cavity in Egypt

DTIC Science & Technology

1987-01-01

of Anaerobic Epidemiological studies have demonstrated a strong positive correlation between oral microorgan- Infections of the Oral Cavity isms and... oral cavity ". Reports published on the gingivitis were reported by the Greek scientist Xen- various aspects of these conditions have confirmed ophen...THE ORAL CAVITY cable to anaerobic synergistic infections. In other words, anaerobic infections have generally been con- Mucous membranes of the

Fatigue Index and Fatigue Rate during an Anaerobic Performance under Hypohydrations

PubMed Central

Naharudin, Mohamed Nashrudin; Yusof, Ashril

2013-01-01

Background Since hypohydration commonly occurs in sports, studies on anaerobic exercise performance under this condition have been extensively carried out. When describing anaerobic performance, authors usually refer to a drop in anaerobic performance as fatigue index (FI) which is conventionally calculated using peak and low power data points. Meanwhile, another possible method in explaining anaerobic fatigue is using the rate constant which is derived from the exponential decline of power output known as fatigue rate (FR). Few studies have demonstrated that there was no change in anaerobic performance under mild hypohydrations. Purpose This study aimed to compare the kinetics of power output using FI and FR of an anaerobic performance (Wingate test) under 2, 3 and 4% state of hypohydrations. Method Thirty two collegiate cyclists (age  = 22±2 years; body weight  = 71.45±3.43 kg; height  = 173.23±0.04 cm) were matched using their baseline anaerobic peak power (APP) then randomly divided into 4 groups of EU (euhydrated), 2H, 3H and 4H respectively. Results As expected the, FI, APP, anaerobic lower power (ALP) and rating of perceived exertion (RPE) did not show significant differences between and within the groups. However, the FR in 3H (0.018±0.005s−1) and 4H (0.019±0.010s−1) were significantly lower than EU (0.033±0.012s−1). Post-test FR also showed significant reduction in 3H and 4H compared to their pre-test values (p<0.05). Conclusion Despite the lack of changes in APP and RPE, subjects in 3H and 4H showed evidence of lower reduction of power output over time. The findings support earlier reports which showed no change in anaerobic performance under mild hypohydrations. The relatively lower FR suggests higher drive in maintaining power output under hypohydrations of 3 and 4% body weight. PMID:24204790

Reduced anaerobic and aerobic performance in children with primary ciliary dyskinesia.

PubMed

Simsek, Senem; Inal-Ince, Deniz; Cakmak, Aslihan; Emiralioglu, Nagehan; Calik-Kutukcu, Ebru; Saglam, Melda; Vardar-Yagli, Naciye; Ozcelik, Hayriye Ugur; Sonbahar-Ulu, Hazal; Bozdemir-Ozel, Cemile; Kiper, Nural; Arikan, Hulya

2018-05-01

Primary ciliary dyskinesia (PCD) restricts lifestyle and increases morbidity. The aim of the study was to investigate anaerobic and aerobic performance in children with PCD and their healthy counterparts. Thirty-one children with PCD and 29 age- and sex-matched healthy subjects were studied. Pulmonary function, hand grip strength (HGS), quadriceps strength (QMS), physical activity, anaerobic capacity (muscle power sprint test), and aerobic performance (modified shuttle walk test (MSWT)) were determined. Pulmonary function, HGS, QMS, mean anaerobic power (MAP), and MSWT distance in PCD were significantly lower than those of healthy subjects (p < 0.05). In PCD, the MAP was significantly correlated with age, FEV 1 , and the mean kcal for 3 days (p < 0.05), and age was its independent predictor (p < 0.05). The MSWT distance was significantly related to gender and weight (p < 0.05), and gender was selected as its independent predictor (p < 0.05). In healthy controls, the MAP was significantly associated with age, gender, FVC, FEV 1 , HGS, QMS, and the mean kcal for three days (p < 0.05). The MSWT distance was significantly related to weight and body mass index in healthy group (p < 0.05). Anaerobic and aerobic performance is impaired in PCD from the early stages. Age determines anaerobic performance. Gender is the determinant of aerobic performance. Whether skeletal muscle characteristics and sex-related changes in body composition affect anaerobic and aerobic capacity in PCD children warrants further study. What is Known: • Exercise performance is determined by anaerobic and aerobic power. • Few studies have shown that PCD patients have lower aerobic performance which is associated with impaired lung function. What is New: • The present research indicated that both anaerobic and aerobic exercise capacity determined using field testing is impaired in PCD from the early stages. • Anaerobic capacity was found to be independently

Molecular characterization of anaerobic sulfur-oxidizing microbial communities in up-flow anaerobic sludge blanket reactor treating municipal sewage.

PubMed

Aida, Azrina A; Hatamoto, Masashi; Yamamoto, Masamitsu; Ono, Shinya; Nakamura, Akinobu; Takahashi, Masanobu; Yamaguchi, Takashi

2014-11-01

A novel wastewater treatment system consisting of an up-flow anaerobic sludge blanket (UASB) reactor and a down-flow hanging sponge (DHS) reactor with sulfur-redox reaction was developed for treatment of municipal sewage under low-temperature conditions. In the UASB reactor, a novel phenomenon of anaerobic sulfur oxidation occurred in the absence of oxygen, nitrite and nitrate as electron acceptors. The microorganisms involved in anaerobic sulfur oxidation have not been elucidated. Therefore, in this study, we studied the microbial communities existing in the UASB reactor that probably enhanced anaerobic sulfur oxidation. Sludge samples collected from the UASB reactor before and after sulfur oxidation were used for cloning and terminal restriction fragment length polymorphism (T-RFLP) analysis of the 16S rRNA genes of the bacterial and archaeal domains. The microbial community structures of bacteria and archaea indicated that the genus Smithella and uncultured bacteria within the phylum Caldiserica were the dominant bacteria groups. Methanosaeta spp. was the dominant group of the domain archaea. The T-RFLP analysis, which was consistent with the cloning results, also yielded characteristic fingerprints for bacterial communities, whereas the archaeal community structure yielded stable microbial community. From these results, it can be presumed that these major bacteria groups, genus Smithella and uncultured bacteria within the phylum Caldiserica, probably play an important role in sulfur oxidation in UASB reactors. Copyright © 2014 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Effect of ammoniacal nitrogen on one-stage and two-stage anaerobic digestion of food waste.

PubMed

Ariunbaatar, Javkhlan; Scotto Di Perta, Ester; Panico, Antonio; Frunzo, Luigi; Esposito, Giovanni; Lens, Piet N L; Pirozzi, Francesco

2015-04-01

This research compares the operation of one-stage and two-stage anaerobic continuously stirred tank reactor (CSTR) systems fed semi-continuously with food waste. The main purpose was to investigate the effects of ammoniacal nitrogen on the anaerobic digestion process. The two-stage system gave more reliable operation compared to one-stage due to: (i) a better pH self-adjusting capacity; (ii) a higher resistance to organic loading shocks; and (iii) a higher conversion rate of organic substrate to biomethane. Also a small amount of biohydrogen was detected from the first stage of the two-stage reactor making this system attractive for biohythane production. As the digestate contains ammoniacal nitrogen, re-circulating it provided the necessary alkalinity in the systems, thus preventing an eventual failure by volatile fatty acids (VFA) accumulation. However, re-circulation also resulted in an ammonium accumulation, yielding a lower biomethane production. Based on the batch experimental results the 50% inhibitory concentration of total ammoniacal nitrogen on the methanogenic activities was calculated as 3.8 g/L, corresponding to 146 mg/L free ammonia for the inoculum used for this research. The two-stage system was affected by the inhibition more than the one-stage system, as it requires less alkalinity and the physically separated methanogens are more sensitive to inhibitory factors, such as ammonium and propionic acid. Copyright © 2014 Elsevier Ltd. All rights reserved.

Microbial Populations Associated with Treatment of an Industrial Dye Effluent in an Anaerobic Baffled Reactor

PubMed Central

Plumb, Jason J.; Bell, Joanne; Stuckey, David C.

2001-01-01

Fluorescent in situ hybridization (FISH) using 16S and 23S rRNA-targeted probes together with construction of an archaeal 16S ribosomal DNA (rDNA) clone library was used to characterize the microbial populations of an anaerobic baffled reactor successfully treating industrial dye waste. Wastewater produced during the manufacture of food dyes containing several different azo and other dye compounds was decolorized and degraded under sulfidogenic and methanogenic conditions. Use of molecular methods to describe microbial populations showed that a diverse group of Bacteria and Archaea was involved in this treatment process. FISH enumeration showed that members of the gamma subclass of the class Proteobacteria and bacteria in the Cytophaga-Flexibacter-Bacteroides phylum, together with sulfate-reducing bacteria, were prominent members of a mixed bacterial population. A combination of FISH probing and analysis of 98 archaeal 16S rDNA clone inserts revealed that together with the bacterial population, a methanogenic population dominated by Methanosaeta species and containing species of Methanobacterium and Methanospirillum and a relatively unstudied methanogen, Methanomethylovorans hollandica, contributed to successful anaerobic treatment of the industrial waste. We suggest that sulfate reducers, or more accurately sulfidogenic bacteria, together with M. hollandica contribute considerably to the treatment process through metabolism of dye-associated sulfonate groups and subsequent conversion of sulfur compounds to carbon dioxide and methane. PMID:11425746

Inhibition of Anaerobic Phosphate Release by Nitric Oxide in Activated Sludge

PubMed Central

Van Niel, E. W. J.; Appeldoorn, K. J.; Zehnder, A. J. B.; Kortstee, G. J. J.

1998-01-01

Activated sludge not containing significant numbers of denitrifying, polyphosphate [poly(P)]-accumulating bacteria was grown in a fill-and-draw system and exposed to alternating anaerobic and aerobic periods. During the aerobic period, poly(P) accumulated up to 100 mg of P · g of (dry) weight. When portions of the sludge were incubated anaerobically in the presence of acetate, 80 to 90% of the intracellular poly(P) was degraded and released as orthophosphate. Degradation of poly(P) was mainly catalyzed by the concerted action of polyphosphate:AMP phosphotransferase and adenylate kinase, resulting in ATP formation. In the presence of 0.3 mM nitric oxide (NO) in the liquid-phase release of phosphate, uptake of acetate, formation of poly-β-hydroxybutyrate, utilization of glycogen, and formation of ATP were severely inhibited or completely abolished. In cell extracts of the sludge, adenylate kinase activity was completely inhibited by 0.15 mM NO. The nature of this inhibition was probably noncompetitive, similar to that with hog adenylate kinase. Activated sludge polyphosphate glucokinase was also completely inhibited by 0.15 mM NO. It is concluded that the inhibitory effect of NO on acetate-mediated phosphate release by the sludge used in this study is due to the inhibition of adenylate kinase in the phosphate-releasing organisms. The inhibitory effect of nitrate and nitrite on phosphate release is probably due to their conversion to NO. The lack of any inhibitory effect of NO on adenylate kinase of the poly(P)-accumulating Acinetobacter johnsonii 210A suggests that this type of organism is not involved in the enhanced biological phosphate removal by the sludges used. PMID:9687452

Anaerobic culture to detect periodontal and caries pathogens

PubMed Central

Tanner, Anne C. R.

2014-01-01

Background Anaerobic culture has been critical in our understanding of the oral microbiotas. Highlight Studies in advanced periodontitis in the 1970’s revealed microbial complexes that associated with different clinical presentations. Taxonomy studies identified species newly-observed in periodontitis as Aggregatibacter (Actinobacillus) actinomycetemcomitans, Campylobacter (Wolinella) rectus and other Campylobacter species, and Tannerella (Bacteroides) forsythia. Anaerobic culture of initial periodontitis showed overlap in the microbiota with gingivitis, and added Selenomonas noxia and Filifactor alocis as putative periodontal pathogens. Porphyromonas gingivalis and T. forsythia were found to be associated with initial periodontitis in adults. The dominant microbiota of dental caries differs from that of periodontitis. The major cariogenic species are acidogenic and acid tolerant species particularly Streptococcus mutans, and Lactobacillus and Bifidobacterium species. Anaerobic culture of severe early childhood caries revealed a widely diverse microbiota, comparable to that observed using cloning and sequencing. The PCR-based cloning approach, however, underestimated Actinobacteria compared with culture. Only a subset of the caries-associated microbiota was acid tolerant, with different segments of the microbiota cultured on blood agar compared to a low pH acid agar. While the major caries-associated species was S. mutans, a new species, Scardovia wiggsiae, was significantly associated with early childhood caries. Higher counts of S. wiggsiae were also observed in initial white spot carious lesions in adolescents. Conclusion In periodontitis and dental caries, anaerobic culture studies of advanced disease provided a comprehensive analysis of the microbiota of these infections. Anaerobic culture highlighted the limitation of PCR with standard primers that underestimate detection of Actinobacteria. PMID:25678835

Anaerobic digestion of organic solid poultry slaughterhouse waste--a review.

PubMed

Salminen, E; Rintala, J

2002-05-01

This work reviews the potential of anaerobic digestion for material recovery and energy production from poultry slaughtering by-products and wastes. First, we describe and quantify organic solid by-products and wastes produced in poultry farming and poultry slaughterhouses and discuss their recovery and disposal options. Then we review certain fundamental aspects of anaerobic digestion considered important for the digestion of solid slaughterhouse wastes. Finally, we present an overview of the future potential and current experience of the anaerobic digestion treatment of these materials.

Implementing Livestock Anaerobic Digestion Projects

EPA Pesticide Factsheets

Page provides information to help make an informed decision about installing an anaerobic digester. Is it a good match for a farm’s organic waste, project financing, development guidelines and permit requirements?

Anaerobic gaseous biofuel production using microalgal biomass - A review.

PubMed

Wirth, Roland; Lakatos, Gergely; Böjti, Tamás; Maróti, Gergely; Bagi, Zoltán; Rákhely, Gábor; Kovács, Kornél L

2018-05-24

Most photosynthetic organisms store and convert solar energy in an aerobic process and produce biomass for various uses. Utilization of biomass for the production of renewable energy carriers employs anaerobic conditions. This review focuses on microalgal biomass and its use for biological hydrogen and methane production. Microalgae offer several advantages compared to terrestrial plants. Strategies to maintain anaerobic environment for biohydrogen production are summarized. Efficient biogas production via anaerobic digestion is significantly affected by the biomass composition, pretreatment strategies and the parameters of the digestion process. Coupled biohydrogen and biogas production increases the efficiency and sustainability of renewable energy production. Copyright © 2018. Published by Elsevier Ltd.

A comparison of the technological effectiveness of dairy wastewater treatment in anaerobic UASB reactor and anaerobic reactor with an innovative design.

PubMed

Jedrzejewska-Cicinska, M; Kozak, K; Krzemieniewski, M

2007-10-01

The present research was an investigation of the influence of an innovative design of reactor filled with polyethylene (PE) granulate on model dairy wastewater treatment efficiency under anaerobic conditions compared to that obtained in a typical UASB reactor. The experiment was conducted at laboratory scale. An innovative reactor was designed with the reaction chamber inclined 30 degrees in relation to the ground with upward waste flow and was filled with PE granular material. Raw model dairy wastewater was fed to two anaerobic reactors of different design at the organic loading rate of 4 kg COD m(-3)d(-1). Throughout the experiment, a higher removal efficiency of organic compounds was observed in the reactor with an innovative design and it was higher by 7.1% on average than in the UASB reactor. The total suspended solids was lower in the wastewater treated in the anaerobic reactor with the innovative design. Applying a PE granulated filling in the chamber of the innovative reactor contributed to an even distribution of sludge biomass in the reactor, reducing washout of anaerobic sludge biomass from the reaction chamber and giving a higher organic compounds removal efficiency.

Comparison of different liquid anaerobic digestion effluents as inocula and nitrogen sources for solid-state batch anaerobic digestion of corn stover.

PubMed

Xu, Fuqing; Shi, Jian; Lv, Wen; Yu, Zhongtang; Li, Yebo

2013-01-01

Effluents from three liquid anaerobic digesters, fed with municipal sewage sludge, food waste, or dairy waste, were evaluated as inocula and nitrogen sources for solid-state batch anaerobic digestion of corn stover in mesophilic reactors. Three feedstock-to-effluent (F/E) ratios (i.e., 2, 4, and 6) were tested for each effluent. At an F/E ratio of 2, the reactor inoculated by dairy waste effluent achieved the highest methane yield of 238.5L/kg VS(feed), while at an F/E ratio of 4, the reactor inoculated by food waste effluent achieved the highest methane yield of 199.6L/kg VS(feed). The microbial population and chemical composition of the three effluents were substantially different. Food waste effluent had the largest population of acetoclastic methanogens, while dairy waste effluent had the largest populations of cellulolytic and xylanolytic bacteria. Dairy waste also had the highest C/N ratio of 8.5 and the highest alkalinity of 19.3g CaCO(3)/kg. The performance of solid-state batch anaerobic digestion reactors was closely related to the microbial status in the liquid anaerobic digestion effluents. Copyright © 2012 Elsevier Ltd. All rights reserved.

How to isolate, identify and determine antimicrobial susceptibility of anaerobic bacteria in routine laboratories?

PubMed

Nagy, E; Boyanova, L; Justesen, U S

2018-02-17

There has been increased interest in the study of anaerobic bacteria that cause human infection during the past decade. Many new genera and species have been described using 16S rRNA gene sequencing of clinical isolates obtained from different infection sites with commercially available special culture media to support the growth of anaerobes. Several systems, such as anaerobic pouches, boxes, jars and chambers provide suitable anaerobic culture conditions to isolate even strict anaerobic bacteria successfully from clinical specimens. Beside the classical, time-consuming identification methods and automated biochemical tests, the use of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry has revolutionized identification of even unusual and slow-growing anaerobes directly from culture plates, providing the possibility of providing timely information about anaerobic infections. The aim of this review article is to present methods for routine laboratories, which carry out anaerobic diagnostics on different levels. Relevant data from the literature mostly published during the last 7 years are encompassed and discussed. The review involves topics on the anaerobes that are members of the commensal microbiota and their role causing infection, the key requirements for collection and transport of specimens, processing of specimens in the laboratory, incubation techniques, identification and antimicrobial susceptibility testing of anaerobic bacteria. Advantages, drawbacks and specific benefits of the methods are highlighted. The present review aims to update and improve anaerobic microbiology in laboratories with optimal conditions as well as encourage its routine implementation in laboratories with restricted resources. Copyright © 2018 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

Caffeine and anaerobic performance: ergogenic value and mechanisms of action.

PubMed

Davis, J K; Green, J Matt

2009-01-01

The effect caffeine elicits on endurance performance is well founded. However, comparatively less research has been conducted on the ergogenic potential of anaerobic performance. Some studies showing no effect of caffeine on performance used untrained subjects and designs often not conducive to observing an ergogenic effect. Recent studies incorporating trained subjects and paradigms specific to intermittent sports activity support the notion that caffeine is ergogenic to an extent with anaerobic exercise. Caffeine seems highly ergogenic for speed endurance exercise ranging in duration from 60 to 180 seconds. However, other traditional models examining power output (i.e. 30-second Wingate test) have shown minimal effect of caffeine on performance. Conversely, studies employing sport-specific methodologies (i.e. hockey, rugby, soccer) with shorter duration (i.e. 4-6 seconds) show caffeine to be ergogenic during high-intensity intermittent exercise. Recent studies show caffeine affects isometric maximal force and offers introductory evidence for enhanced muscle endurance for lower body musculature. However, isokinetic peak torque, one-repetition maximum and muscular endurance for upper body musculature are less clear. Since relatively few studies exist with resistance training, a definite conclusion cannot be reached on the extent caffeine affects performance. It was previously thought that caffeine mechanisms were associated with adrenaline (epinephrine)-induced enhanced free-fatty acid oxidation and consequent glycogen sparing, which is the leading hypothesis for the ergogenic effect. It would seem unlikely that the proposed theory would result in improved anaerobic performance, since exercise is dominated by oxygen-independent metabolic pathways. Other mechanisms for caffeine have been suggested, such as enhanced calcium mobilization and phosphodiesterase inhibition. However, a normal physiological dose of caffeine in vivo does not indicate this mechanism plays a

Evaluation of the rotary drum reactor process as pretreatment technology of municipal solid waste for thermophilic anaerobic digestion and biogas production.

PubMed

Gikas, Petros; Zhu, Baoning; Batistatos, Nicolas Ion; Zhang, Ruihong

2018-06-15

Municipal solid waste (MSW) contains a large fraction of biodegradable organic materials. When disposed in landfills, these materials can cause adverse environmental impact due to gaseous emissions and leachate generation. This study was performed with an aim of effectively separating the biodegradable materials from a Mechanical Biological Treatment (MBT) facility and treating them in well-controlled anaerobic digesters for biogas production. The rotary drum reactor (RDR) process (a sub-process of the MBT facilities studied in the present work) was evaluated as an MSW pretreatment technology for separating and preparing the biodegradable materials in MSW to be used as feedstock for anaerobic digestion. The RDR processes used in six commercial MSW treatment plants located in the USA were surveyed and sampled. The samples of the biodegradable materials produced by the RDR process were analyzed for chemical and physical characteristics as well as anaerobically digested in the laboratory using batch reactors under thermophilic conditions. The moisture content, TS, VS and C/N of the samples varied between 64.7 and 44.4%, 55.6 to 35.3%, 27.0 to 41.3% and 24.5 to 42.7, respectively. The biogas yield was measured to be between 533.0 and 675.6 mL g -1 VS after 20 days of digestion. Approximately 90% of the biogas was produced during the first 13 days. The average methane content of the biogas was between 58.0 and 59.9%. The results indicated that the biodegradable materials separated from MSW using the RDR processes could be used as an excellent feedstock for anaerobic digestion. The digester residues may be further processed for compost production or further energy recovery by using thermal conversion processes such as combustion or gasification. Copyright © 2017. Published by Elsevier Ltd.

Deep sequencing-based analysis of the anaerobic stimulon in Neisseria gonorrhoeae

PubMed Central

2011-01-01

Background Maintenance of an anaerobic denitrification system in the obligate human pathogen, Neisseria gonorrhoeae, suggests that an anaerobic lifestyle may be important during the course of infection. Furthermore, mounting evidence suggests that reduction of host-produced nitric oxide has several immunomodulary effects on the host. However, at this point there have been no studies analyzing the complete gonococcal transcriptome response to anaerobiosis. Here we performed deep sequencing to compare the gonococcal transcriptomes of aerobically and anaerobically grown cells. Using the information derived from this sequencing, we discuss the implications of the robust transcriptional response to anaerobic growth. Results We determined that 198 chromosomal genes were differentially expressed (~10% of the genome) in response to anaerobic conditions. We also observed a large induction of genes encoded within the cryptic plasmid, pJD1. Validation of RNA-seq data using translational-lacZ fusions or RT-PCR demonstrated the RNA-seq results to be very reproducible. Surprisingly, many genes of prophage origin were induced anaerobically, as well as several transcriptional regulators previously unknown to be involved in anaerobic growth. We also confirmed expression and regulation of a small RNA, likely a functional equivalent of fnrS in the Enterobacteriaceae family. We also determined that many genes found to be responsive to anaerobiosis have also been shown to be responsive to iron and/or oxidative stress. Conclusions Gonococci will be subject to many forms of environmental stress, including oxygen-limitation, during the course of infection. Here we determined that the anaerobic stimulon in gonococci was larger than previous studies would suggest. Many new targets for future research have been uncovered, and the results derived from this study may have helped to elucidate factors or mechanisms of virulence that may have otherwise been overlooked. PMID:21251255

[Acidophilic methanogens and their applications in anaerobic digestion].

PubMed

Guo, Xiao-Hui; Wu, Wei-Xiang; Han, Zhi-Ying; Shi, De-Zhi

2011-02-01

Methanogens play an important role in global carbon cycle. There exists a range of unknown methanogenic archaea in acidic peat lands, among which, acidophilic methanogens have attracted increasing research interests because of their special metabolic characteristics. To introduce acidophilic methanogens in the anaerobic digestion process of high concentration organic wastes or waste water could essentially overcome the inhibition of acid accumulation on the methanogens and help reduce the operation cost, broadening the industrial application of anaerobic bio-treatment technology. In this paper, we reviewed the recent researches on acidophilic methanogens, with the focus on enrichment and isolation methods, physiological and biochemical characters, metabolic characteristics, and application of molecular biology. The potential applications of acidophilic methanogens in anaerobic digestion process were analyzed and proposed, and the directions for further researches were suggested.

University of Wisconsin Oshkosh Anaerobic Dry Digestion Facility

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

Koker, John; Lizotte, Michael

The University of Wisconsin Oshkosh Anaerobic Dry Digestion Facility is a demonstration project that supported the first commercial-scale use in the United States of high solids, static pile technology for anaerobic digestion of organic waste to generate biogas for use in generating electricity and heat. The research adds to the understanding of startup, operation and supply chain issues for anaerobic digester technology. Issues and performance were documented for equipment installation and modifications, feedstock availability and quality, weekly loading and unloading of digestion chambers, chemical composition of biogas produced, and energy production. This facility also demonstrated an urban industrial ecology approachmore » to siting such facilities near sewage treatment plants (to capture and use excess biogas generated by the plants) and organic yard waste collection sites (a source of feedstock).« less

Acetate Metabolism in Anaerobes from the Domain Archaea

PubMed Central

Ferry, James G.

2015-01-01

Acetate and acetyl-CoA play fundamental roles in all of biology, including anaerobic prokaryotes from the domains Bacteria and Archaea, which compose an estimated quarter of all living protoplasm in Earth’s biosphere. Anaerobes from the domain Archaea contribute to the global carbon cycle by metabolizing acetate as a growth substrate or product. They are components of anaerobic microbial food chains converting complex organic matter to methane, and many fix CO2 into cell material via synthesis of acetyl-CoA. They are found in a diversity of ecological habitats ranging from the digestive tracts of insects to deep-sea hydrothermal vents, and synthesize a plethora of novel enzymes with biotechnological potential. Ecological investigations suggest that still more acetate-metabolizing species with novel properties await discovery. PMID:26068860

Fungal fermentation on anaerobic digestate for lipid-based biofuel production.

PubMed

Zhong, Yuan; Liu, Zhiguo; Isaguirre, Christine; Liu, Yan; Liao, Wei

2016-01-01

Anaerobic digestate is the effluent from anaerobic digestion of organic wastes. It contains a significant amount of nutrients and lignocellulosic materials, even though anaerobic digestion consumed a large portion of organic matters in the wastes. Utilizing the nutrients and lignocellulosic materials in the digestate is critical to significantly improve efficiency of anaerobic digestion technology and generate value-added chemical and fuel products from the organic wastes. Therefore, this study focused on developing an integrated process that uses biogas energy to power fungal fermentation and converts remaining carbon sources, nutrients, and water in the digestate into biofuel precursor-lipid. The process contains two unit operations of anaerobic digestion and digestate utilization. The digestate utilization includes alkali treatment of the mixture feed of solid and liquid digestates, enzymatic hydrolysis for mono-sugar release, overliming detoxification, and fungal fermentation for lipid accumulation. The experimental results conclude that 5 h and 30 °C were the preferred conditions for the overliming detoxification regarding lipid accumulation of the following fungal cultivation. The repeated-batch fungal fermentation enhanced lipid accumulation, which led to a final lipid concentration of 3.16 g/L on the digestate with 10% dry matter. The mass and energy balance analysis further indicates that the digestate had enough water for the process uses and the biogas energy was able to balance the needs of individual unit operations. A fresh-water-free and energy-positive process of lipid production from anaerobic digestate was achieved by integrating anaerobic digestion and fungal fermentation. The integration addresses the issues that both biofuel industry and waste management encounter-high water and energy demand of biofuel precursor production and few digestate utilization approaches of organic waste treatment.

Anaerobic biodegradation of (emerging) organic contaminants in the aquatic environment.

PubMed

Ghattas, Ann-Kathrin; Fischer, Ferdinand; Wick, Arne; Ternes, Thomas A

2017-06-01

Although strictly anaerobic conditions prevail in several environmental compartments, up to now, biodegradation studies with emerging organic contaminants (EOCs), such as pharmaceuticals and personal care products, have mainly focused on aerobic conditions. One of the reasons probably is the assumption that the aerobic degradation is more energetically favorable than degradation under strictly anaerobic conditions. Certain aerobically recalcitrant contaminants, however, are biodegraded under strictly anaerobic conditions and little is known about the organisms and enzymatic processes involved in their degradation. This review provides a comprehensive survey of characteristic anaerobic biotransformation reactions for a variety of well-studied, structurally rather simple contaminants (SMOCs) bearing one or a few different functional groups/structural moieties. Furthermore it summarizes anaerobic degradation studies of more complex contaminants with several functional groups (CMCs), in soil, sediment and wastewater treatment. While strictly anaerobic conditions are able to promote the transformation of several aerobically persistent contaminants, the variety of observed reactions is limited, with reductive dehalogenations and the cleavage of ether bonds being the most prevalent. Thus, it becomes clear that the transferability of degradation mechanisms deduced from culture studies of SMOCs to predict the degradation of CMCs, such as EOCs, in environmental matrices is hampered due the more complex chemical structure bearing different functional groups, different environmental conditions (e.g. matrix, redox, pH), the microbial community (e.g. adaptation, competition) and the low concentrations typical for EOCs. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Simultaneous isolation of anaerobic bacteria from udder abscesses and mastitic milk in lactating dairy cows.

PubMed

Greeff, A S; du Preez, J H

1985-12-01

A variety of non-sporulating anaerobic bacterial species were isolated from udder abscesses in 10 lactating dairy cows. Fifty percent of the abscesses yielded multiple anaerobic species and the other 50% only 1 species. The anaerobic bacteria, however, were always accompanied by classical facultative anaerobic mastitogenic bacteria. In four of the five cows also afflicted with mastitis in the quarters with abscesses, the anaerobic and facultative anaerobic bacteria were identical. Peptococcus indolicus was the most commonly isolated organism followed by Eubacterium and Bacteroides spp. Bacteroides fragilis was resistant to penicillin, ampicillin and tetracycline.

Prevailing Torque Locking Feature in Threaded Fasteners Using Anaerobic Adhesive

NASA Technical Reports Server (NTRS)

Hernandez, Alan; Hess, Daniel P.

2016-01-01

This paper presents results from tests to assess the use of anaerobic adhesive for providing a prevailing torque locking feature in threaded fasteners. Test procedures are developed and tests are performed on three fastener materials, four anaerobic adhesives, and both unseated assembly conditions. Five to ten samples are tested for each combination. Tests for initial use, reuse without additional adhesive, and reuse with additional adhesive are performed for all samples. A 48-hour cure time was used for all initial use and reuse tests. Test data are presented as removal torque versus removal angle with the specification required prevailing torque range added for performance assessment. Percent specification pass rates for the all combinations of fastener material, adhesive, and assembly condition are tabulated and reveal use of anaerobic adhesive as a prevailing torque locking feature is viable. Although not every possible fastener material and anaerobic adhesive combination provides prevailing torque values within specification, any combination can be assessed using the test procedures presented. Reuse without additional anaerobic adhesive generally provides some prevailing torque, and in some cases within specification. Reuse with additional adhesive often provides comparable removal torque data as in initial use.

Total protein of whole saliva as a biomarker of anaerobic threshold.

PubMed

Bortolini, Miguel Junior Sordi; De Agostini, Guilherme Gularte; Reis, Ismair Teodoro; Lamounier, Romeu Paulo Martins Silva; Blumberg, Jeffrey B; Espindola, Foued Salmen

2009-09-01

Saliva provides a convenient and noninvasive matrix for assessing specific physiological parameters, including some biomarkers of exercise. We investigated whether the total protein concentration of whole saliva (TPWS) would reflect the anaerobic threshold during an incremental exercise test. After a warm-up period, 13 nonsmoking men performed a maximum incremental exercise on a cycle ergometer. Blood and stimulated saliva were collected during the test. The TPWS anaerobic threshold (PAT) was determined using the Dmax method. The PAT was correlated with the blood lactate anaerobic threshold (AT; r = .93, p < .05). No significant difference (p = .16) was observed between PAT and AT. Thus, TPWS provides a convenient and noninvasive matrix for determining the anaerobic threshold during incremental exercise tests.

Anaerobic Metabolism in the N-Limited Green Alga Selenastrum minutum1

PubMed Central

Vanlerberghe, Greg C.; Joy, Kenneth W.; Turpin, David H.

1991-01-01

We have determined the flow of 15N into free amino acids of the N-limited green alga Selenastrum minutum (Naeg.) Collins after addition of 15NH4+ to aerobic or anaerobic cells. Under aerobic conditions, only a small proportion of the N assimilated was retained in the free amino acid pool. However, under anaerobic conditions almost all assimilated NH4+ accumulates in alanine. This is a unique feature of anaerobic NH4+ assimilation. The pathway of carbon flow to alanine results in the production of ATP and reductant which matches exactly the requirements of NH4+ assimilation. Alanine synthesis is therefore an excellent strategy to maintain energy and redox balance during anaerobic NH4+ assimilation. PMID:16668034

Some unique features of alkaliphilic anaerobes

NASA Astrophysics Data System (ADS)

Roof, Erin; Pikuta, Elena; Otto, Christopher; Williams, George; Hoover, Richard

2013-09-01

This article explores two topics involving the examination of four strains of alkaliphilic anaerobes. The first topic was dedicated to detection of the ability of microorganisms to metabolize alternative chirality substrates. Two saccharolytic anaerobic bacteria were chosen for the first experiment: Anaerovirgula multivorans strain SCAT, which is gram positive and spore-forming; and Spirochaeta dissipatitropha, strain ASpC2T, which is gram negative. It was found that both checked sugarlytics were able to use L-ribose and L-arabinose, as growth substrates. The second part was concerned of study a chemolithotrophy in two halo-alkaliphilic sulfate reducing bacteria: Desulfonatornum thiodismutans strain MLF1T and Desulfonatronum lacustre strain Z-7951T. The experiments with lithotrophs had demonstrated that strain MLF1T was capable to grow without any organic source of carbon, while strain Z-7951T had required at least 2 mM sodium acetate for growth. Anaerobic technique was used for preparation of the growth media and maintenance of these bacterial cultures. Standard methods for Gram, spore, and flagella staining were applied for characterization of cytomorphology. In this article, the results of the experiments performed on cytological, physiological, and biochemical levels are presented and discussed.

Microbial degradation of 4-monobrominated diphenyl ether in an aerobic sludge and the DGGE analysis of diversity.

PubMed

Chen, Chun-Yao; Wang, Chun-Kang; Shih, Yang-Hsin

2010-07-01

Polybrominated diphenyl ethers (PBDEs) were applied as flame retardant additives in polymers for many plastic and electronic products. Due to their ubiquitous distribution in the environment, potential toxicity to human and tendency for bioaccumulation, PBDEs have raised public safety concern. In this study we examined the degradation of 4-monobrominated diphenyl ether (4-BDE) in aerobic sludge, as a model for PBDE biodegradation. Degradation of 4-BDE was observed in aerobic sludge. Co-metabolism with toluene or diphenyl ether facilitated 4-BDE biodegradation in terms of kinetics and efficiency. Diphenyl ether seems to perform slightly better as an auxiliary carbon source than toluene in facilitating 4-BDE degradation. During the experiment we identified diphenyl ether by gas chromatography/mass spectrometry(GC/MS), which indicates that an anaerobic debromination has occurred. Bacterial community composition was monitored with denaturing gradient gel electrophoresis. The fragments enriched in 4-BDE-degrading aerobic sludge samples belong to presumably a novel anaerobic Clostridiales species distantly related to all known debrominating microbes. This suggests that 4-BDE biodegradation can occur in anaerobic micro-niche in an apparently aerobic environment, by a previously unknown bacterial species. These findings can provide better understandings of biodegradation of brominated diphenyl ethers and can facilitate the prediction of the fate of PBDEs in the environment.

Bacterial ecology of abattoir wastewater treated by an anaerobic digestor.

PubMed

Jabari, Linda; Gannoun, Hana; Khelifi, Eltaief; Cayol, Jean-Luc; Godon, Jean-Jacques; Hamdi, Moktar; Fardeau, Marie-Laure

2016-01-01

Wastewater from an anaerobic treatment plant at a slaughterhouse was analysed to determine the bacterial biodiversity present. Molecular analysis of the anaerobic sludge obtained from the treatment plant showed significant diversity, as 27 different phyla were identified. Firmicutes, Proteobacteria, Bacteroidetes, Thermotogae, Euryarchaeota (methanogens), and msbl6 (candidate division) were the dominant phyla of the anaerobic treatment plant and represented 21.7%, 18.5%, 11.5%, 9.4%, 8.9%, and 8.8% of the total bacteria identified, respectively. The dominant bacteria isolated were Clostridium, Bacteroides, Desulfobulbus, Desulfomicrobium, Desulfovibrio and Desulfotomaculum. Our results revealed the presence of new species, genera and families of microorganisms. The most interesting strains were characterised. Three new bacteria involved in anaerobic digestion of abattoir wastewater were published. Copyright © 2015 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

Mass spectrometric identification of intermediates in the O2-driven [4Fe-4S] to [2Fe-2S] cluster conversion in FNR

PubMed Central

Crack, Jason C.; Thomson, Andrew J.

2017-01-01

The iron-sulfur cluster containing protein Fumarate and Nitrate Reduction (FNR) is the master regulator for the switch between anaerobic and aerobic respiration in Escherichia coli and many other bacteria. The [4Fe-4S] cluster functions as the sensory module, undergoing reaction with O2 that leads to conversion to a [2Fe-2S] form with loss of high-affinity DNA binding. Here, we report studies of the FNR cluster conversion reaction using time-resolved electrospray ionization mass spectrometry. The data provide insight into the reaction, permitting the detection of cluster conversion intermediates and products, including a [3Fe-3S] cluster and persulfide-coordinated [2Fe-2S] clusters [[2Fe-2S](S)n, where n = 1 or 2]. Analysis of kinetic data revealed a branched mechanism in which cluster sulfide oxidation occurs in parallel with cluster conversion and not as a subsequent, secondary reaction to generate [2Fe-2S](S)n species. This methodology shows great potential for broad application to studies of protein cofactor–small molecule interactions. PMID:28373574

Dynamics and genetic diversification of Escherichia coli during experimental adaptation to an anaerobic environment

PubMed Central

Finn, Thomas J.; Shewaramani, Sonal; Leahy, Sinead C.; Janssen, Peter H.

2017-01-01

Background Many bacteria are facultative anaerobes, and can proliferate in both anoxic and oxic environments. Under anaerobic conditions, fermentation is the primary means of energy generation in contrast to respiration. Furthermore, the rates and spectra of spontaneous mutations that arise during anaerobic growth differ to those under aerobic growth. A long-term selection experiment was undertaken to investigate the genetic changes that underpin how the facultative anaerobe, Escherichia coli, adapts to anaerobic environments. Methods Twenty-one populations of E. coli REL4536, an aerobically evolved 10,000th generation descendent of the E. coli B strain, REL606, were established from a clonal ancestral culture. These were serially sub-cultured for 2,000 generations in a defined minimal glucose medium in strict aerobic and strict anaerobic environments, as well as in a treatment that fluctuated between the two environments. The competitive fitness of the evolving lineages was assessed at approximately 0, 1,000 and 2,000 generations, in both the environment of selection and the alternative environment. Whole genome re-sequencing was performed on random colonies from all lineages after 2,000-generations. Mutations were identified relative to the ancestral genome, and based on the extent of parallelism, traits that were likely to have contributed towards adaptation were inferred. Results There were increases in fitness relative to the ancestor among anaerobically evolved lineages when tested in the anaerobic environment, but no increases were found in the aerobic environment. For lineages that had evolved under the fluctuating regime, relative fitness increased significantly in the anaerobic environment, but did not increase in the aerobic environment. The aerobically-evolved lineages did not increase in fitness when tested in either the aerobic or anaerobic environments. The strictly anaerobic lineages adapted more rapidly to the anaerobic environment than did the

Closed nutrient recycling via microbial catabolism in an eco-engineered self regenerating mixed anaerobic microbiome for hydrogenotrophic methanogenesis.

PubMed

Savvas, Savvas; Donnelly, Joanne; Patterson, Tim P; Dinsdale, Richard; Esteves, Sandra R

2017-03-01

A novel eco-engineered mixed anaerobic culture was successfully demonstrated for the first time to be capable of continuous regeneration in nutrient limiting conditions. Microbial catabolism has been found to support a closed system of nutrients able to enrich a culture of lithotrophic methanogens and provide microbial cell recycling. After enrichment, the hydrogenotrophic species was the dominating methanogens while a bacterial substratum was responsible for the redistribution of nutrients. q-PCR results indicated that 7% of the total population was responsible for the direct conversion of the gases. The efficiency of H 2 /CO 2 conversion to CH 4 reached 100% at a gassing rate of above 60v/v/d. The pH of the culture media was effectively sustained at optimal levels (pH 7-8) through a buffering system created by the dissolved CO 2 . The novel approach can reduce the process nutrient/metal requirement and enhance the environmental and financial performance of hydrogenotrophic methanogenesis for renewable energy storage. Copyright © 2016 Elsevier Ltd. All rights reserved.

Anaerobic digestion of municipal wastewater sludges using anaerobic fluidized bed bioreactor.

PubMed

Mustafa, Nizar; Elbeshbishy, Elsayed; Nakhla, George; Zhu, Jesse

2014-11-01

The anaerobic digestion of primary sludge (PS) and thickened waste activated sludge (TWAS) using an anaerobic fluidized bed bioreactor (AnFBR) employing zeolite particles as the carrier media was investigated at different organic loading rates (OLRs). PS was tested at OLRs from 4.2 to 39kgCOD/m(3)-d corresponding to hydraulic retention times (HRTs) from 1.0 to 8.9days. The highest COD removal and VSS destruction efficiencies for primary sludge of 85% and 88%, respectively, were achieved at an HRT of 8.9days and OLR of 4.2kgCOD/m(3)-d. For TWAS, VSS destruction efficiencies varied from 42% at an HRT of 2.6days and OLR of 13.1kgCOD/m(3)-d to 69% at an HRT of 8.8days and an OLR of 4.2kgCOD/m(3)-d. The first-order COD biodegradation rates in the AnFBR for PS and TWAS were 0.4d(-1) and 0.1d(-1), respectively, almost double the rates in conventional high-rate digesters. Copyright © 2014 Elsevier Ltd. All rights reserved.

Early Microbial Evolution: The Age of Anaerobes

PubMed Central

Martin, William F.; Sousa, Filipa L.

2016-01-01

In this article, the term “early microbial evolution” refers to the phase of biological history from the emergence of life to the diversification of the first microbial lineages. In the modern era (since we knew about archaea), three debates have emerged on the subject that deserve discussion: (1) thermophilic origins versus mesophilic origins, (2) autotrophic origins versus heterotrophic origins, and (3) how do eukaryotes figure into early evolution. Here, we revisit those debates from the standpoint of newer data. We also consider the perhaps more pressing issue that molecular phylogenies need to recover anaerobic lineages at the base of prokaryotic trees, because O2 is a product of biological evolution; hence, the first microbes had to be anaerobes. If molecular phylogenies do not recover anaerobes basal, something is wrong. Among the anaerobes, hydrogen-dependent autotrophs—acetogens and methanogens—look like good candidates for the ancestral state of physiology in the bacteria and archaea, respectively. New trees tend to indicate that eukaryote cytosolic ribosomes branch within their archaeal homologs, not as sisters to them and, furthermore tend to root archaea within the methanogens. These are major changes in the tree of life, and open up new avenues of thought. Geochemical methane synthesis occurs as a spontaneous, abiotic exergonic reaction at hydrothermal vents. The overall similarity between that reaction and biological methanogenesis fits well with the concept of a methanogenic root for archaea and an autotrophic origin of microbial physiology. PMID:26684184

Anaerobic fitness tests: what are we measuring?

PubMed

Van Praagh, Emmanuel

2007-01-01

Anaerobic fitness, during growth and development, has not received the same attention from researchers as aerobic fitness. This is surprising given the level of anaerobic energy used daily during childhood and adolescence. During physical activity and sport, the child is spontaneously more attracted to short-burst movements than to long-term activities. It is, however, well known that in anaerobic activities such as sprint cycling, sprint running or sprint swimming, the child's performance is distinctly poorer than that of the adult. This partly reflects the child's lesser ability to generate mechanical energy from chemical energy sources during short-term high-intensity work or exercise. Direct measurements of the rate or capacity of anaerobic pathways for energy turnover presents several ethical and methodological difficulties. Therefore, rather than measure energy supply, pediatric exercise scientists have concentrated on measuring short-term power output by means of standardized protocol tests such as short-term cycling power tests, running tests or vertical jump tests. There is, however, no perfect test and, therefore, it is important to acknowledge the benefits and limitations of each testing method. Mass-related short-term power output was shown to increase dramatically during growth and development, whereas the corresponding increase in peak blood lactate was considerably lower. This suggests that the observed difference between children and adolescents during short-term power output testing may be related to neuromuscular factors, hormonal factors and improved motor coordination.

Analysis of fatty acid composition of anaerobic rumen fungi.

PubMed

Koppová, I; Novotná, Z; Strosová, L; Fliegerová, K

2008-01-01

The fatty acid (FA) composition of fresh mycelia of anaerobic rumen fungi was determined. The fatty acids methyl esters (FAME) of six strains belonging to four genera (Neocallimastix, Caecomyces, Orpinomyces, Anaeromyces) and one unknown strain were analyzed by gas chromatography. All studied fungi possess the same FAs but differences were found in their relative concentrations. The FA profile of anaerobic fungi comprises carbon chains of length ranging from 12 to 24; the most common fatty acids were stearic (C(18:0)), arachidic (C(20:0)), heneicosanoic (C(21:0)), behenic (C(22:0)), tricosanoic (C(23:0)) and lignoceric (C(24:0)) with relative amount representing >4% of total FA. Significant differences were determined for heptadecanoic, oleic, behenic and tricosanoic acids. Rumen anaerobic fungi can contain very long chain fatty acids; we found unsaturated fatty acids including cis-11-eicosenoic (C(20:1)), cis-11,14-eicosadienoic (C(20:2)), erucic (C(22:1n9)), cis-13,16-docosadienoic (C(22:2)) and nervonic (C(24:1)) acids in very small amounts but their presence seems to be unique for anaerobic fungi.

Oxygen induces mutation in a strict anaerobe, Prevotella melaninogenica.

PubMed

Takumi, Shota; Komatsu, Masaharu; Aoyama, Kohji; Watanabe, Kunitomo; Takeuchi, Toru

2008-05-15

Strict anaerobes are highly sensitive to oxygen, but the mutagenicity of oxygen in strict anaerobes has not been well understood. Prevotella melaninogenica, a strict anaerobe, is susceptible to oxygen and shows an increase in oxidative DNA damage upon exposure to oxygen. In this study, we have investigated the mutagenicity of oxygen and the types of mutations induced by oxygen. Exposure to oxygen decreased cell survival and increased the levels of 8-oxo-deoxyguanosine (8-oxodG). The frequency of rifampicin-resistant mutants was markedly increased after exposure to oxygen. After sequencing a 254-bp fragment of the rpoB gene, which encodes the beta subunit of bacterial RNA polymerase, a target molecule of rifampicin, we found that most mutants induced by oxygen had GC to TA transversions, a signature of 8-oxodG. In addition, all detected single-nucleotide changes would lead to amino acid changes that confer rifampicin resistance. These results indicate that oxygen is mutagenic in a strict anaerobe, P. melaninogenica, and its mutagenic characteristics could be analyzed with this experimental system.

Optimisation of substrate blends in anaerobic co-digestion using adaptive linear programming.

PubMed

García-Gen, Santiago; Rodríguez, Jorge; Lema, Juan M

2014-12-01

Anaerobic co-digestion of multiple substrates has the potential to enhance biogas productivity by making use of the complementary characteristics of different substrates. A blending strategy based on a linear programming optimisation method is proposed aiming at maximising COD conversion into methane, but simultaneously maintaining a digestate and biogas quality. The method incorporates experimental and heuristic information to define the objective function and the linear restrictions. The active constraints are continuously adapted (by relaxing the restriction boundaries) such that further optimisations in terms of methane productivity can be achieved. The feasibility of the blends calculated with this methodology was previously tested and accurately predicted with an ADM1-based co-digestion model. This was validated in a continuously operated pilot plant, treating for several months different mixtures of glycerine, gelatine and pig manure at organic loading rates from 1.50 to 4.93 gCOD/Ld and hydraulic retention times between 32 and 40 days at mesophilic conditions. Copyright © 2014 Elsevier Ltd. All rights reserved.

Life Cycle Assessment of high ligno-cellulosic biomass pyrolysis coupled with anaerobic digestion.

PubMed

Righi, Serena; Bandini, Vittoria; Marazza, Diego; Baioli, Filippo; Torri, Cristian; Contin, Andrea

2016-07-01

A Life Cycle Assessment is conducted on pyrolysis coupled to anaerobic digestion to treat corn stovers and to obtain bioenergy and biochar. The analysis takes into account the feedstock treatment process, the fate of products and the indirect effects due to crop residue removal. The biochar is considered to be used as solid fuel for coal power plants or as soil conditioner. All results are compared with a corresponding fossil-fuel-based scenario. It is shown that the proposed system always enables relevant primary energy savings of non-renewable sources and a strong reduction of greenhouse gases emissions without worsening the abiotic resources depletion. Conversely, the study points out that the use of corn stovers for mulch is critical when considering acidification and eutrophication impacts. Therefore, removal of corn stovers from the fields must be planned carefully. Copyright © 2016. Published by Elsevier Ltd.

Illumina sequencing-based analysis of a microbial community enriched under anaerobic methane oxidation condition coupled to denitrification revealed coexistence of aerobic and anaerobic methanotrophs.

PubMed

Siniscalchi, Luciene Alves Batista; Leite, Laura Rabelo; Oliveira, Guilherme; Chernicharo, Carlos Augusto Lemos; de Araújo, Juliana Calabria

2017-07-01

Methane is produced in anaerobic environments, such as reactors used to treat wastewaters, and can be consumed by methanotrophs. The composition and structure of a microbial community enriched from anaerobic sewage sludge under methane-oxidation condition coupled to denitrification were investigated. Denaturing gradient gel electrophoresis (DGGE) analysis retrieved sequences of Methylocaldum and Chloroflexi. Deep sequencing analysis revealed a complex community that changed over time and was affected by methane concentration. Methylocaldum (8.2%), Methylosinus (2.3%), Methylomonas (0.02%), Methylacidiphilales (0.45%), Nitrospirales (0.18%), and Methanosarcinales (0.3%) were detected. Despite denitrifying conditions provided, Nitrospirales and Methanosarcinales, known to perform anaerobic methane oxidation coupled to denitrification (DAMO) process, were in very low abundance. Results demonstrated that aerobic and anaerobic methanotrophs coexisted in the reactor together with heterotrophic microorganisms, suggesting that a diverse microbial community was important to sustain methanotrophic activity. The methanogenic sludge was a good inoculum to enrich methanotrophs, and cultivation conditions play a selective role in determining community composition.

Potential of hydrolysis of particulate COD in extended anaerobic conditions to enhance biological phosphorous removal.

PubMed

Jabari, P; Yuan, Q; Oleszkiewicz, J A

2016-11-01

The effect of anaerobic hydrolysis of particulate COD (pCOD) on biological phosphorous removal in extended anaerobic condition was investigated through (i) sequencing batch reactors (SBR)s with anaerobic hydraulic retention time (HRT) of 0.8, 2, and 4 h; (ii) batch tests using biomass from a full scale biological nutrient removal (BNR) plant; and (iii) activated sludge modeling (BioWin 4.1 simulation). The results from long-term SBRs operation showed that phosphorus removal was correlated to the ratio of filtered COD (FCOD) to total phosphorus (TP) in the influent. Under conditions with low FCOD/TP ratio (average of 20) in the influent, extending anaerobic HRT to 4 h in the presence of pCOD did not significantly improve overall phosphorous removal. During the period with high FCOD/TP ratio (average of 37) in the influent, all SBRs removed phosphorous completely, and the long anaerobic HRT did not have negative effect on overall phosphorous removal. The batch tests also showed that pCOD at different concentration during 4 h test did not affect the rate of anaerobic phosphorus release. The rate of anaerobic hydrolysis of pCOD was significantly low and extending the anaerobic HRT was ineffective. The simulation (BioWin 4.1) of SBRs with low influent FCOD/TP ratio showed that the default kinetics of anaerobic hydrolysis in ASM2d overestimated phosphorous removal in the SBRs (high anaerobic hydrolysis of pCOD). The default anaerobic hydrolysis rate in BioWin 4.1 (ten times lower) could produce similar phosphorous removal to that in the experiment. Results showed that the current kinetics of anaerobic hydrolysis in ASM2d could lead to considerable error in predicting phosphorus removal in processes with extended anaerobic HRT. Biotechnol. Bioeng. 2016;113: 2377-2385. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Anaerobic Thermophiles

PubMed Central

Canganella, Francesco; Wiegel, Juergen

2014-01-01

The term “extremophile” was introduced to describe any organism capable of living and growing under extreme conditions. With the further development of studies on microbial ecology and taxonomy, a variety of “extreme” environments have been found and an increasing number of extremophiles are being described. Extremophiles have also been investigated as far as regarding the search for life on other planets and even evaluating the hypothesis that life on Earth originally came from space. The first extreme environments to be largely investigated were those characterized by elevated temperatures. The naturally “hot environments” on Earth range from solar heated surface soils and water with temperatures up to 65 °C, subterranean sites such as oil reserves and terrestrial geothermal with temperatures ranging from slightly above ambient to above 100 °C, to submarine hydrothermal systems with temperatures exceeding 300 °C. There are also human-made environments with elevated temperatures such as compost piles, slag heaps, industrial processes and water heaters. Thermophilic anaerobic microorganisms have been known for a long time, but scientists have often resisted the belief that some organisms do not only survive at high temperatures, but actually thrive under those hot conditions. They are perhaps one of the most interesting varieties of extremophilic organisms. These microorganisms can thrive at temperatures over 50 °C and, based on their optimal temperature, anaerobic thermophiles can be subdivided into three main groups: thermophiles with an optimal temperature between 50 °C and 64 °C and a maximum at 70 °C, extreme thermophiles with an optimal temperature between 65 °C and 80 °C, and finally hyperthermophiles with an optimal temperature above 80 °C and a maximum above 90 °C. The finding of novel extremely thermophilic and hyperthermophilic anaerobic bacteria in recent years, and the fact that a large fraction of them belong to the Archaea has

Biochemical Mechanisms and Microorganisms Involved in Anaerobic Testosterone Metabolism in Estuarine Sediments

PubMed Central

Shih, Chao-Jen; Chen, Yi-Lung; Wang, Chia-Hsiang; Wei, Sean T.-S.; Lin, I-Ting; Ismail, Wael A.; Chiang, Yin-Ru

2017-01-01

Current knowledge on the biochemical mechanisms underlying microbial steroid metabolism in anaerobic ecosystems is extremely limited. Sulfate, nitrate, and iron [Fe (III)] are common electron acceptors for anaerobes in estuarine sediments. Here, we investigated anaerobic testosterone metabolism in anaerobic sediments collected from the estuary of Tamsui River, Taiwan. The anaerobic sediment samples were spiked with testosterone (1 mM) and individual electron acceptors (10 mM), including nitrate, Fe3+, and sulfate. The analysis of androgen metabolites indicated that testosterone biodegradation under denitrifying conditions proceeds through the 2,3-seco pathway, whereas testosterone biodegradation under iron-reducing conditions may proceed through an unidentified alternative pathway. Metagenomic analysis and PCR-based functional assays suggested that Thauera spp. were the major testosterone degraders in estuarine sediment samples incubated with testosterone and nitrate. Thauera sp. strain GDN1, a testosterone-degrading betaproteobacterium, was isolated from the denitrifying sediment sample. This strain tolerates a broad range of salinity (0–30 ppt). Although testosterone biodegradation did not occur under sulfate-reducing conditions, we observed the anaerobic biotransformation of testosterone to estrogens in some testosterone-spiked sediment samples. This is unprecedented since biotransformation of androgens to estrogens is known to occur only under oxic conditions. Our metagenomic analysis suggested that Clostridium spp. might play a role in this anaerobic biotransformation. These results expand our understanding of microbial metabolism of steroids under strictly anoxic conditions. PMID:28848528

A miniaturized counting technique for anaerobic bacteria.

PubMed

Sharpe, A N; Pettipher, G L; Lloyd, G R

1976-12-01

A miniaturized counting technique gave results as good as the pour-plate and Most Probable Number (MPN) techniques for enumeration of clostridia spp. and anaerobic isolates from the gut. Highest counts were obtained when ascorbic acid (1%) and dithiothreitol (0.015%) were added to the reinforced clostridial medium used for counting. This minimized the effect of exposure to air before incubation. The miniature technique allowed up to 40 samples to be plated and incubated in one McIntosh-Filde's-type anaerobic jar, compared with 3 or 4 by the normal pour plate.

Electroactive microorganisms in bulk solution contribute significantly to methane production in bioelectrochemical anaerobic reactor.

PubMed

Feng, Qing; Song, Young-Chae; Ahn, Yongtae

2018-07-01

The role of anaerobic microorganisms suspended in the bulk solution on methane production was investigated in a bioelectrochemical anaerobic reactor with the electrode polarized at 0.5 V. The electron transfer from substrate to methane and hydrogen were 25% and 7.5%, respectively, in the absence of the anaerobic microorganisms in the bulk solution. As the anaerobic microorganisms increased to 4400 mg/L, the electrons transferred to methane increased to 83.3% but decreased to 0.3% in hydrogen. The electroactive microorganisms (EAM), including exoelectrogens and electrotrophs, enriched in the bulk solution that confirmed by the redox peaks in the cyclic voltammogram was proportional to the anaerobic microorganism. The methane yield based on COD removal was dependent on the anaerobic microorganisms in the bulk solution rather than on the bioelectrode surface. The EAM suspended in the bulk solution are enriched by the polarized electrode, and significantly improve methane production in bioelectrochemical anaerobic reactor. Copyright © 2018 Elsevier Ltd. All rights reserved.

My Lifelong Passion for Biochemistry and Anaerobic Microorganisms.

PubMed

Thauer, Rudolf Kurt

2015-01-01

Early parental influence led me first to medical school, but after developing a passion for biochemistry and sensing the need for a deeper foundation, I changed to chemistry. During breaks between semesters, I worked in various biochemistry labs to acquire a feeling for the different areas of investigation. The scientific puzzle that fascinated me most was the metabolism of the anaerobic bacterium Clostridium kluyveri, which I took on in 1965 in Karl Decker's lab in Freiburg, Germany. I quickly realized that little was known about the biochemistry of strict anaerobes such as clostridia, methanogens, acetogens, and sulfate-reducing bacteria and that these were ideal model organisms to study fundamental questions of energy conservation, CO2 fixation, and the evolution of metabolic pathways. My passion for anaerobes was born then and is unabated even after 50 years of study.

A fuzzy logic approach to control anaerobic digestion.

PubMed

Domnanovich, A M; Strik, D P; Zani, L; Pfeiffer, B; Karlovits, M; Braun, R; Holubar, P

2003-01-01

One of the goals of the EU-Project AMONCO (Advanced Prediction, Monitoring and Controlling of Anaerobic Digestion Process Behaviour towards Biogas Usage in Fuel Cells) is to create a control tool for the anaerobic digestion process, which predicts the volumetric organic loading rate (Bv) for the next day, to obtain a high biogas quality and production. The biogas should contain a high methane concentration (over 50%) and a low concentration of components toxic for fuel cells, e.g. hydrogen sulphide, siloxanes, ammonia and mercaptanes. For producing data to test the control tool, four 20 l anaerobic Continuously Stirred Tank Reactors (CSTR) are operated. For controlling two systems were investigated: a pure fuzzy logic system and a hybrid-system which contains a fuzzy based reactor condition calculation and a hierachial neural net in a cascade of optimisation algorithms.

Treatment of low strength industrial cluster wastewater by anaerobic hybrid reactor.

PubMed

Kumar, Amit; Yadav, Asheesh Kumar; Sreekrishnan, T R; Satya, Santosh; Kaushik, C P

2008-05-01

The study was aimed at treating the complex, combined wastewater generated in Mangolpuri industrial cluster. It was considered as a low strength wastewater with respect to its organic content. Anaerobic treatment of this wastewater was studied using an anaerobic hybrid reactor (AHR) which combined the best features of both the upflow anaerobic sludge blanket (UASB) reactor and anaerobic fluidized bed rector (AFBR). The performance of the reactor under different organic and hydraulic loading rates were studied. The COD removal reached 94% at an organic loading rate (OLR) of 2.08 kg COD m(-3)d(-1) at an hydraulic retention time (HRT) of 6.0 h. The granules developed were characterized in terms of their diameter and terminal settling velocity.

Directed evolution reveals unexpected epistatic interactions that alter metabolic regulation and enable anaerobic xylose use by Saccharomyces cerevisiae

DOE PAGES

Sato, Trey K.; Tremaine, Mary; Parreiras, Lucas S.; ...

2016-10-14

The inability of native Saccharomyces cerevisiae to convert xylose from plant biomass into biofuels remains a major challenge for the production of renewable bioenergy. Despite extensive knowledge of the regulatory networks controlling carbon metabolism in yeast, little is known about how to reprogram S. cerevisiae to ferment xylose at rates comparable to glucose. Here we combined genome sequencing, proteomic profiling, and metabolomic analyses to identify and characterize the responsible mutations in a series of evolved strains capable of metabolizing xylose aerobically or anaerobically. We report that rapid xylose conversion by engineered and evolved S. cerevisiae strains depends upon epistatic interactionsmore » among genes encoding a xylose reductase ( GRE3), a component of MAP Kinase (MAPK) signaling ( HOG1), a regulator of Protein Kinase A (PKA) signaling ( IRA2), and a scaffolding protein for mitochondrial iron-sulfur (Fe-S) cluster biogenesis ( ISU1). Interestingly, the mutation in IRA2 only impacted anaerobic xylose consumption and required the loss of ISU1 function, indicating a previously unknown connection between PKA signaling, Fe-S cluster biogenesis, and anaerobiosis. Proteomic and metabolomic comparisons revealed that the xylose-metabolizing mutant strains exhibit altered metabolic pathways relative to the parental strain when grown in xylose. Further analyses revealed that interacting mutations in HOG1 and ISU1 unexpectedly elevated mitochondrial respiratory proteins and enabled rapid aerobic respiration of xylose and other non-fermentable carbon substrates. Lastly, our findings suggest a surprising connection between Fe-S cluster biogenesis and signaling that facilitates aerobic respiration and anaerobic fermentation of xylose, underscoring how much remains unknown about the eukaryotic signaling systems that regulate carbon metabolism.« less

Directed Evolution Reveals Unexpected Epistatic Interactions That Alter Metabolic Regulation and Enable Anaerobic Xylose Use by Saccharomyces cerevisiae.

PubMed

Sato, Trey K; Tremaine, Mary; Parreiras, Lucas S; Hebert, Alexander S; Myers, Kevin S; Higbee, Alan J; Sardi, Maria; McIlwain, Sean J; Ong, Irene M; Breuer, Rebecca J; Avanasi Narasimhan, Ragothaman; McGee, Mick A; Dickinson, Quinn; La Reau, Alex; Xie, Dan; Tian, Mingyuan; Reed, Jennifer L; Zhang, Yaoping; Coon, Joshua J; Hittinger, Chris Todd; Gasch, Audrey P; Landick, Robert

2016-10-01

The inability of native Saccharomyces cerevisiae to convert xylose from plant biomass into biofuels remains a major challenge for the production of renewable bioenergy. Despite extensive knowledge of the regulatory networks controlling carbon metabolism in yeast, little is known about how to reprogram S. cerevisiae to ferment xylose at rates comparable to glucose. Here we combined genome sequencing, proteomic profiling, and metabolomic analyses to identify and characterize the responsible mutations in a series of evolved strains capable of metabolizing xylose aerobically or anaerobically. We report that rapid xylose conversion by engineered and evolved S. cerevisiae strains depends upon epistatic interactions among genes encoding a xylose reductase (GRE3), a component of MAP Kinase (MAPK) signaling (HOG1), a regulator of Protein Kinase A (PKA) signaling (IRA2), and a scaffolding protein for mitochondrial iron-sulfur (Fe-S) cluster biogenesis (ISU1). Interestingly, the mutation in IRA2 only impacted anaerobic xylose consumption and required the loss of ISU1 function, indicating a previously unknown connection between PKA signaling, Fe-S cluster biogenesis, and anaerobiosis. Proteomic and metabolomic comparisons revealed that the xylose-metabolizing mutant strains exhibit altered metabolic pathways relative to the parental strain when grown in xylose. Further analyses revealed that interacting mutations in HOG1 and ISU1 unexpectedly elevated mitochondrial respiratory proteins and enabled rapid aerobic respiration of xylose and other non-fermentable carbon substrates. Our findings suggest a surprising connection between Fe-S cluster biogenesis and signaling that facilitates aerobic respiration and anaerobic fermentation of xylose, underscoring how much remains unknown about the eukaryotic signaling systems that regulate carbon metabolism.

Directed Evolution Reveals Unexpected Epistatic Interactions That Alter Metabolic Regulation and Enable Anaerobic Xylose Use by Saccharomyces cerevisiae

PubMed Central

Tremaine, Mary; Hebert, Alexander S.; Myers, Kevin S.; Sardi, Maria; Dickinson, Quinn; Reed, Jennifer L.; Zhang, Yaoping; Coon, Joshua J.; Hittinger, Chris Todd; Gasch, Audrey P.; Landick, Robert

2016-01-01

The inability of native Saccharomyces cerevisiae to convert xylose from plant biomass into biofuels remains a major challenge for the production of renewable bioenergy. Despite extensive knowledge of the regulatory networks controlling carbon metabolism in yeast, little is known about how to reprogram S. cerevisiae to ferment xylose at rates comparable to glucose. Here we combined genome sequencing, proteomic profiling, and metabolomic analyses to identify and characterize the responsible mutations in a series of evolved strains capable of metabolizing xylose aerobically or anaerobically. We report that rapid xylose conversion by engineered and evolved S. cerevisiae strains depends upon epistatic interactions among genes encoding a xylose reductase (GRE3), a component of MAP Kinase (MAPK) signaling (HOG1), a regulator of Protein Kinase A (PKA) signaling (IRA2), and a scaffolding protein for mitochondrial iron-sulfur (Fe-S) cluster biogenesis (ISU1). Interestingly, the mutation in IRA2 only impacted anaerobic xylose consumption and required the loss of ISU1 function, indicating a previously unknown connection between PKA signaling, Fe-S cluster biogenesis, and anaerobiosis. Proteomic and metabolomic comparisons revealed that the xylose-metabolizing mutant strains exhibit altered metabolic pathways relative to the parental strain when grown in xylose. Further analyses revealed that interacting mutations in HOG1 and ISU1 unexpectedly elevated mitochondrial respiratory proteins and enabled rapid aerobic respiration of xylose and other non-fermentable carbon substrates. Our findings suggest a surprising connection between Fe-S cluster biogenesis and signaling that facilitates aerobic respiration and anaerobic fermentation of xylose, underscoring how much remains unknown about the eukaryotic signaling systems that regulate carbon metabolism. PMID:27741250

Adaptation and Antibiotic Tolerance of Anaerobic Burkholderia pseudomallei ▿ †

PubMed Central

Hamad, Mohamad A.; Austin, Chad R.; Stewart, Amanda L.; Higgins, Mike; Vázquez-Torres, Andrés; Voskuil, Martin I.

2011-01-01

The Gram-negative bacterium Burkholderia pseudomallei is the etiological agent of melioidosis and is remarkably resistant to most classes of antibacterials. Even after months of treatment with antibacterials that are relatively effective in vitro, there is a high rate of treatment failure, indicating that this pathogen alters its patterns of antibacterial susceptibility in response to cues encountered in the host. The pathology of melioidosis indicates that B. pseudomallei encounters host microenvironments that limit aerobic respiration, including the lack of oxygen found in abscesses and in the presence of nitric oxide produced by macrophages. We investigated whether B. pseudomallei could survive in a nonreplicating, oxygen-deprived state and determined if this physiological state was tolerant of conventional antibacterials. B. pseudomallei survived initial anaerobiosis, especially under moderately acidic conditions similar to those found in abscesses. Microarray expression profiling indicated a major shift in the physiological state of hypoxic B. pseudomallei, including induction of a variety of typical anaerobic-environment-responsive genes and genes that appear specific to anaerobic B. pseudomallei. Interestingly, anaerobic B. pseudomallei was unaffected by antibacterials typically used in therapy. However, it was exquisitely sensitive to drugs used against anaerobic pathogens. After several weeks of anaerobic culture, a significant loss of viability was observed. However, a stable subpopulation that maintained complete viability for at least 1 year was established. Thus, during the course of human infection, if a minor subpopulation of bacteria inhabited an oxygen-restricted environment, it might be indifferent to traditional therapy but susceptible to antibiotics frequently used to treat anaerobic infections. PMID:21537012

Advanced anaerobic bioconversion of lignocellulosic waste for the melissa life support system

NASA Astrophysics Data System (ADS)

Lissens, G.; Verstraete, W.; Albrecht, T.; Brunner, G.; Creuly, C.; Dussap, G.; Kube, J.; Maerkl, H.; Lasseur, C.

The feasibility of nearly-complete conversion of lignocellulosic waste (70% food crops, 20% faecal matter and 10% green algae) into biogas was investigated in the context of the MELiSSA loop (Micro-Ecological Life Support System Alternative). The treatment comprised a series of processes, i.e. a mesophilic laboratory scale CSTR (continuously stirred tank reactor), an upflow biofilm reactor, a fiber liquefaction reactor employing the rumen bacterium Fibrobacter succinogenes and a hydrothermolysis system in near-critical water. By the one-stage CSTR, a biogas yield of 75% with a specific biogas production of 0.37 l biogas g-1 VSS (volatile suspended solids) added at a RT (hydraulic retention time) of 20-25 d was obtained. Biogas yields could not be increased considerably at higher RT, indicating the depletion of readily available substrate after 25 d. The solids present in the CSTR-effluent were subsequently treated in two ways. Hydrothermal treatment (T ˜ 310-350C, p ˜ 240 bar) resulted in effective carbon liquefaction (50-60% without and 83% with carbon dioxide saturation) and complete sanitation of the residue. Application of the cellulolytic Fibrobacter succinogenes converted remaining cellulose contained in the CSTR-effluent into acetate and propionate mainly. Subsequent anaerobic digestion of the hydrothermolysis and the Fibrobacter hydrolysates allowed conversion of 48-60% and 30%, respectively. Thus, the total process yielded biogas corresponding with conversions up to 90% of the original organic matter. It appears that particularly mesophilic digestion in conjunction with hydrothermolysis offers interesting features for (nearly) the MELiSSA system. The described additional technologies show that complete and hygienic carbon and energy recovery from human waste within MELiSSA is technically feasible, provided that the extra energy needed for the thermal treatment is guaranteed.

Efficient Anaerobic Digestion of Microalgae Biomass: Proteins as a Key Macromolecule.

PubMed

Magdalena, Jose Antonio; Ballesteros, Mercedes; González-Fernandez, Cristina

2018-05-06

Biogas generation is the least complex technology to transform microalgae biomass into bioenergy. Since hydrolysis has been pointed out as the rate limiting stage of anaerobic digestion, the main challenge for an efficient biogas production is the optimization of cell wall disruption/hydrolysis. Among all tested pretreatments, enzymatic treatments were demonstrated not only very effective in disruption/hydrolysis but they also revealed the impact of microalgae macromolecular composition in the anaerobic process. Although carbohydrates have been traditionally recognized as the polymers responsible for the low microalgae digestibility, protease addition resulted in the highest organic matter solubilization and the highest methane production. However, protein solubilization during the pretreatment can result in anaerobic digestion inhibition due to the release of large amounts of ammonium nitrogen. The possible solutions to overcome these negative effects include the reduction of protein biomass levels by culturing the microalgae in low nitrogen media and the use of ammonia tolerant anaerobic inocula. Overall, this review is intended to evidence the relevance of microalgae proteins in different stages of anaerobic digestion, namely hydrolysis and methanogenesis.

Identification of anaerobic selenate-respiring bacteria from aquatic sediments.

PubMed

Narasingarao, Priya; Häggblom, Max M

2007-06-01

The diversity population of microorganisms with the capability to use selenate as a terminal electron acceptor, reducing it to selenite and elemental selenium by the process known as dissimilatory selenate reduction, is largely unknown. The overall objective of this study was to gain an in-depth understanding of anaerobic biotransformation of selenium in the environment, particularly anaerobic respiration, and to characterize the microorganisms catalyzing this process. Here, we demonstrate the isolation and characterization of four novel anaerobic dissimilatory selenate-respiring bacteria enriched from a variety of sources, including sediments from three different water bodies in Chennai, India, and a tidal estuary in New Jersey. Strains S5 and S7 from India, strain KM from the Meadowlands, NJ, and strain pn1, categorized as a laboratory contaminant, were all phylogenetically distinct, belonging to various phyla in the bacterial domain. The 16S rRNA gene sequence shows that strain S5 constitutes a new genus belonging to Chrysiogenetes, while strain S7 belongs to the Deferribacteres, with greater than 98% 16S rRNA gene similarity to Geovibrio ferrireducens. Strain KM is related to Malonomonas rubra, Pelobacter acidigallici, and Desulfuromusa spp., with 96 to 97% 16S rRNA gene similarity. Strain pn1 is 99% similar to Pseudomonas stutzeri. Strains S5, S7, and KM are obligately anaerobic selenate-respiring microorganisms, while strain pn1 is facultatively anaerobic. Besides respiring selenate, all these strains also respire nitrate.

On the kinetics of anaerobic power

PubMed Central

2012-01-01

Background This study investigated two different mathematical models for the kinetics of anaerobic power. Model 1 assumes that the work power is linear with the work rate, while Model 2 assumes a linear relationship between the alactic anaerobic power and the rate of change of the aerobic power. In order to test these models, a cross country skier ran with poles on a treadmill at different exercise intensities. The aerobic power, based on the measured oxygen uptake, was used as input to the models, whereas the simulated blood lactate concentration was compared with experimental results. Thereafter, the metabolic rate from phosphocreatine break down was calculated theoretically. Finally, the models were used to compare phosphocreatine break down during continuous and interval exercises. Results Good similarity was found between experimental and simulated blood lactate concentration during steady state exercise intensities. The measured blood lactate concentrations were lower than simulated for intensities above the lactate threshold, but higher than simulated during recovery after high intensity exercise when the simulated lactate concentration was averaged over the whole lactate space. This fit was improved when the simulated lactate concentration was separated into two compartments; muscles + internal organs and blood. Model 2 gave a better behavior of alactic energy than Model 1 when compared against invasive measurements presented in the literature. During continuous exercise, Model 2 showed that the alactic energy storage decreased with time, whereas Model 1 showed a minimum value when steady state aerobic conditions were achieved. During interval exercise the two models showed similar patterns of alactic energy. Conclusions The current study provides useful insight on the kinetics of anaerobic power. Overall, our data indicate that blood lactate levels can be accurately modeled during steady state, and suggests a linear relationship between the alactic

TEST RESULTS FOR FUEL CELL OPERATION ON ANAEROBIC DIGESTER GAS

EPA Science Inventory

EPA, in conjunction with ONSI Corp., embarked on a project to define, design, test, and assess a fuel cell energy recovery system for application at anaerobic digester waste water (sewage) treatment plants. Anaerobic digester gas (ADG) is produced at these plants during the proce...

pH-Dependent Uptake of Fumaric Acid in Saccharomyces cerevisiae under Anaerobic Conditions

PubMed Central

Jamalzadeh, Elaheh; Verheijen, Peter J. T.; Heijnen, Joseph J.

2012-01-01

Microbial production of C4 dicarboxylic acids from renewable resources has gained renewed interest. The yeast Saccharomyces cerevisiae is known as a robust microorganism and is able to grow at low pH, which makes it a suitable candidate for biological production of organic acids. However, a successful metabolic engineering approach for overproduction of organic acids requires an incorporation of a proper exporter to increase the productivity. Moreover, low-pH fermentations, which are desirable for facilitating the downstream processing, may cause back diffusion of the undissociated acid into the cells with simultaneous active export, thereby creating an ATP-dissipating futile cycle. In this work, we have studied the uptake of fumaric acid in S. cerevisiae in carbon-limited chemostat cultures under anaerobic conditions. The effect of the presence of fumaric acid at different pH values (3 to 5) has been investigated in order to obtain more knowledge about possible uptake mechanisms. The experimental results showed that at a cultivation pH of 5.0 and an external fumaric acid concentration of approximately 0.8 mmol · liter−1, the fumaric acid uptake rate was unexpectedly high and could not be explained by diffusion of the undissociated form across the plasma membrane alone. This could indicate the presence of protein-mediated import. At decreasing pH levels, the fumaric acid uptake rate was found to increase asymptotically to a maximum level. Although this observation is in accordance with protein-mediated import, the presence of a metabolic bottleneck for fumaric acid conversion under anaerobic conditions could not be excluded. PMID:22113915

Mainstream upflow nitritation-anammox system with hybrid anaerobic pretreatment: Long-term performance and microbial community dynamics.

PubMed

Li, Xiaojin; Sun, Shan; Yuan, Heyang; Badgley, Brian D; He, Zhen

2017-11-15

Mainstream nitritation-anammox is of strong interest to energy- and resource-efficient domestic wastewater treatment. However, there lack in-depth studies of pretreatment, tests of actual wastewater, and examination of long-term performance. Herein, an upflow nitritation-anammox granular reactor has been investigated to treat primary effluent with a hybrid anaerobic reactor (HAR) as pretreatment for more than 300 days. This system achieved 92% of COD removal, 75% of which was accomplished by the HAR, and had an average final effluent COD concentration of 22 mg L -1 . More than 90% of ammonium was removed in the nitritation-anammox reactor, achieving a nitrogen removal rate of 81.0 g N m -3  d -1 in the last stage. The accumulation of sulfate-reducing bacteria in the HAR evidenced the effect of sulfate on COD removal and subsequent nitrogen removal. Anammox bacteria (predominantly Ca. Jettenia asiatica) accounted for up to 40.2% of total granular communities, but their abundance decreased over time in the suspended communities. The dynamics of major metabolisms and functional genes involved in nitrogen conversion were predicted by PICRUSt based on the taxonomic data, providing more insights into the functions of the microbial communities. These results have demonstrated the effectiveness and importance of anaerobic pretreatment to successful mainstream nitritation-anammox. Copyright © 2017 Elsevier Ltd. All rights reserved.

Phylogenetic diversity and in situ detection of eukaryotes in anaerobic sludge digesters.

PubMed

Matsubayashi, Miri; Shimada, Yusuke; Li, Yu-You; Harada, Hideki; Kubota, Kengo

2017-01-01

Eukaryotic communities in aerobic wastewater treatment processes are well characterized, but little is known about them in anaerobic processes. In this study, abundance, diversity and morphology of eukaryotes in anaerobic sludge digesters were investigated by quantitative real-time PCR (qPCR), 18S rRNA gene clone library construction and catalyzed reporter deposition-fluorescence in situ hybridization (CARD-FISH). Samples were taken from four different anaerobic sludge digesters in Japan. Results of qPCR of rRNA genes revealed that Eukarya accounted from 0.1% to 1.4% of the total number of microbial rRNA gene copy numbers. The phylogenetic affiliations of a total of 251 clones were Fungi, Alveolata, Viridiplantae, Amoebozoa, Rhizaria, Stramenopiles and Metazoa. Eighty-five percent of the clones showed less than 97.0% sequence identity to described eukaryotes, indicating most of the eukaryotes in anaerobic sludge digesters are largely unknown. Clones belonging to the uncultured lineage LKM11 in Cryptomycota of Fungi were most abundant in anaerobic sludge, which accounted for 50% of the total clones. The most dominant OTU in each library belonged to either the LKM11 lineage or the uncultured lineage A31 in Alveolata. Principal coordinate analysis indicated that the eukaryotic and prokaryotic community structures were related. The detection of anaerobic eukaryotes, including the members of the LKM11 and A31 lineages in anaerobic sludge digesters, by CARD-FISH revealed their sizes in the range of 2-8 μm. The diverse and uncultured eukaryotes in the LKM11 and the A31 lineages are common and ecologically relevant members in anaerobic sludge digester.

Antimicrobial susceptibility of clinical isolates of anaerobic bacteria in Ontario, 2010-2011.

PubMed

Marchand-Austin, Alex; Rawte, Prasad; Toye, Baldwin; Jamieson, Frances B; Farrell, David J; Patel, Samir N

2014-08-01

The local epidemiology of antimicrobial susceptibility patterns in anaerobic bacteria is important in guiding the empiric treatment of infections. However, susceptibility data are very limited on anaerobic organisms, particularly among non-Bacteroides organisms. To determine susceptibility profiles of clinically-significant anaerobic bacteria in Ontario Canada, anaerobic isolates from sterile sites submitted to Public Health Ontario Laboratory (PHOL) for identification and susceptibility testing were included in this study. Using the E-test method, isolates were tested for various antimicrobials including, penicillin, cefoxitin, clindamycin, meropenem, piperacillin-tazobactam and metronidazole. The MIC results were interpreted based on guidelines published by Clinical and Laboratory Standards Institute. Of 2527 anaerobic isolates submitted to PHOL, 1412 were either from sterile sites or bronchial lavage, and underwent susceptibility testing. Among Bacteroides fragilis, 98.2%, 24.7%, 1.6%, and 1.2% were resistant to penicillin, clindamycin, piperacillin-tazobactam, and metronidazole, respectively. Clostridium perfringens was universally susceptible to penicillin, piperacillin-tazobactam, and meropenem, whereas 14.2% of other Clostridium spp. were resistant to penicillin. Among Gram-positive anaerobes, Actinomyces spp., Parvimonas micra and Propionibacterium spp. were universally susceptible to β-lactams. Eggerthella spp., Collinsella spp., and Eubacterium spp. showed variable resistance to penicillin. Among Gram-negative anaerobes, Fusobacterium spp., Prevotella spp., and Veillonella spp. showed high resistance to penicillin but were universally susceptible to meropenem and piperacillin-tazobactam. The detection of metronidazole resistant B. fragilis is concerning as occurrence of these isolates is extremely rare. These data highlight the importance of ongoing surveillance to provide clinically relevant information to clinicians for empiric management of

Diversity of Anaerobic Microbes in Spacecraft Assembly Clean Rooms ▿ †

PubMed Central

Probst, Alexander; Vaishampayan, Parag; Osman, Shariff; Moissl-Eichinger, Christine; Andersen, Gary L.; Venkateswaran, Kasthuri

2010-01-01

Although the cultivable and noncultivable microbial diversity of spacecraft assembly clean rooms has been previously documented using conventional and state-of-the-art molecular techniques, the occurrence of obligate anaerobes within these clean rooms is still uncertain. Therefore, anaerobic bacterial communities of three clean-room facilities were analyzed during assembly of the Mars Science Laboratory rover. Anaerobic bacteria were cultured on several media, and DNA was extracted from suitable anaerobic enrichments and examined with conventional 16S rRNA gene clone library, as well as high-density phylogenetic 16S rRNA gene microarray (PhyloChip) technologies. The culture-dependent analyses predominantly showed the presence of clostridial and propionibacterial strains. The 16S rRNA gene sequences retrieved from clone libraries revealed distinct microbial populations associated with each clean-room facility, clustered exclusively within gram-positive organisms. PhyloChip analysis detected a greater microbial diversity, spanning many phyla of bacteria, and provided a deeper insight into the microbial community structure of the clean-room facilities. This study presents an integrated approach for assessing the anaerobic microbial population within clean-room facilities, using both molecular and cultivation-based analyses. The results reveal that highly diverse anaerobic bacterial populations persist in the clean rooms even after the imposition of rigorous maintenance programs and will pose a challenge to planetary protection implementation activities. PMID:20228115

Anaerobic thermophilic culture system

DOEpatents

Ljungdahl, Lars G.; Wiegel, Jurgen K. W.

1981-01-01

A mixed culture system of the newly discovered microorganism Thermoanaerobacter ethanolicus ATCC31550 and the microorganism Clostridium thermocellum ATCC31549 is described. In a mixed nutrient culture medium that contains cellulose, these microorganisms have been coupled and cultivated to efficiently ferment cellulose to produce recoverable quantities of ethanol under anaerobic, thermophilic conditions.

Enhanced hydrolysis and methane yield by applying microaeration pretreatment to the anaerobic co-digestion of brown water and food waste.

PubMed

Lim, Jun Wei; Wang, Jing-Yuan

2013-04-01

Microaeration has been used conventionally for the desulphurization of biogas, and recently it was shown to be an alternative pretreatment to enhance hydrolysis of the anaerobic digestion (AD) process. Previous studies on microaeration pretreatment were limited to the study of substrates with complex organic matter, while little has been reported on its effect on substrates with higher biodegradability such as brown water and food waste. Due to the lack of consistent microaeration intensities, previous studies were not comparable and thus inconclusive in proving the effectiveness of microaeration to the overall AD process. In this study, the role of microaeration pretreatment in the anaerobic co-digestion of brown water and food waste was evaluated in batch-tests. After a 4-day pretreatment with 37.5 mL-O2/L(R)-d added to the liquid phase of the reactor, the methane production of substrates were monitored in anaerobic conditions over the next 40 days. The added oxygen was consumed fully by facultative microorganisms and a reducing environment for organic matter degradation was maintained. Other than higher COD solubilization, microaeration pretreatment led to greater VFA accumulation and the conversion of other short chain fatty acids to acetate. This could be due to enhanced activities of hydrolytic and acidogenic bacteria and the degradation of slowly biodegradable compounds under microaerobic conditions. This study also found that the nature of inoculum influenced the effects of microaeration as a 21% and 10% increase in methane yield was observed when pretreatment was applied to inoculated substrates, and substrates without inoculum, respectively. Copyright © 2012 Elsevier Ltd. All rights reserved.

Influence of fluid dynamics on anaerobic digestion of food waste for biogas production.

PubMed

Wang, Fengping; Zhang, Cunsheng; Huo, Shuhao

2017-05-01

To enhance the stability and efficiency of an anaerobic process, the influences of fluid dynamics on the performance of anaerobic digestion and sludge granulation were investigated using computational fluid dynamics (CFD). Four different propeller speeds (20, 60, 100, 140 r/min) were adopted for anaerobic digestion of food waste in a 30 L continuously stirred tank reactor (CSTR). Experimental results indicated that the methane yield increased with increasing the propeller speed within the experimental range. Results from CFD simulation and sludge granulation showed that the optimum propeller speed for anaerobic digestion was 100 r/min. Lower propeller speed (20 r/min) inhibited mass transfer and resulted in the failure of anaerobic digestion, while higher propeller speed (140 r/min) would lead to higher energy loss and system instability. Under this condition, anaerobic digestion could work effectively with higher efficiency of mass transfer which facilitated sludge granulation and biogas production. The corresponding mean liquid velocity and shear strain rate were 0.082 m/s and 10.48 s -1 , respectively. Moreover, compact granular sludge could be formed, with lower energy consumption. CFD was successfully used to study the influence of fluid dynamics on the anaerobic digestion process. The key parameters of the optimum mixing condition for anaerobic digestion of food waste in a 30 L CSTR including liquid velocity and shear strain rate were obtained using CFD, which were of paramount significance for the scale-up of the bioreactor. This study provided a new way for the optimization and scale-up of the anaerobic digestion process in CSTR based on the fluid dynamics analysis.

Anaerobic muscle strengthening physical activity and depression severity among USA adults.

PubMed

Cangin, Causenge; Harris, Randall; Binkley, Philip; Schwartzbaum, Judith; Focht, Brian

2018-06-01

We investigated the association between depression and anaerobic physical activity (while controlling aerobic physical activity), using a nationally representative sample of USA adults ( n  = 7354) who participated in the cross sectional National Health and Nutrition Examination Survey (NHANES, 1999-2006). We defined depression using the validated "Patient Health Questionnaire" (PHQ 9 ) scale of 0-27 as PHQ 9   ≥  10. Severity of depression was classified by clinically established PHQ 9 levels: mild (5-9), dysthymic (10-14), moderate (15-19), and major depression ( ≥ 20). We used logistic regression to estimate adjusted odds ratios of depression associated with distinct types of activity (only aerobic, only anaerobic, combined regime). We used multinomial logistic regression to examine associations of anaerobic activity with various severity levels of depression (mild, dysthymic, moderate, and major depression) with adjustment for aerobic activity. Women had higher prevalence of depression than men (8.4% versus 5.7%), whereas anaerobic muscle strengthening activity was more common in men than women (35% versus 24%). Adjusting for aerobic activity , anaerobic activity was inversely associated with depression (PHQ 9   ≥  10) in women under 50 (OR = 0.57; 95%CI = 0.41-0.81), all women (OR = 0.59; 0.43-0.80), men under 50 (OR = 0.85; 0.58-1.2), and all men (OR = 0.72; 0.51-1.01). Anaerobic activity was inversely associated with severity level of depressive symptoms in women and men. The combined regimen of anaerobic muscle strengthening activity and meeting the Physical Activity Guideline for America (PAGA) was related to the lowest odds ratio of depression in women (OR = 0.50; 95%CI = 0.33-0.75) and men (OR = 0.39; 95%CI = 0.23-0.62). Independent of aerobic physical activity, anaerobic muscle strengthening activity is significantly and inversely associated with depression among USA adults.

Direct conversion of plant biomass to ethanol by engineered Caldicellulosiruptor bescii

PubMed Central

Chung, Daehwan; Cha, Minseok; Guss, Adam M.; Westpheling, Janet

2014-01-01

Ethanol is the most widely used renewable transportation biofuel in the United States, with the production of 13.3 billion gallons in 2012 [John UM (2013) Contribution of the Ethanol Industry to the Economy of the United States]. Despite considerable effort to produce fuels from lignocellulosic biomass, chemical pretreatment and the addition of saccharolytic enzymes before microbial bioconversion remain economic barriers to industrial deployment [Lynd LR, et al. (2008) Nat Biotechnol 26(2):169–172]. We began with the thermophilic, anaerobic, cellulolytic bacterium Caldicellulosiruptor bescii, which efficiently uses unpretreated biomass, and engineered it to produce ethanol. Here we report the direct conversion of switchgrass, a nonfood, renewable feedstock, to ethanol without conventional pretreatment of the biomass. This process was accomplished by deletion of lactate dehydrogenase and heterologous expression of a Clostridium thermocellum bifunctional acetaldehyde/alcohol dehydrogenase. Whereas wild-type C. bescii lacks the ability to make ethanol, 70% of the fermentation products in the engineered strain were ethanol [12.8 mM ethanol directly from 2% (wt/vol) switchgrass, a real-world substrate] with decreased production of acetate by 38% compared with wild-type. Direct conversion of biomass to ethanol represents a new paradigm for consolidated bioprocessing, offering the potential for carbon neutral, cost-effective, sustainable fuel production. PMID:24889625

Direct conversion of plant biomass to ethanol by engineered Caldicellulosiruptor bescii.

PubMed

Chung, Daehwan; Cha, Minseok; Guss, Adam M; Westpheling, Janet

2014-06-17

Ethanol is the most widely used renewable transportation biofuel in the United States, with the production of 13.3 billion gallons in 2012 [John UM (2013) Contribution of the Ethanol Industry to the Economy of the United States]. Despite considerable effort to produce fuels from lignocellulosic biomass, chemical pretreatment and the addition of saccharolytic enzymes before microbial bioconversion remain economic barriers to industrial deployment [Lynd LR, et al. (2008) Nat Biotechnol 26(2):169-172]. We began with the thermophilic, anaerobic, cellulolytic bacterium Caldicellulosiruptor bescii, which efficiently uses unpretreated biomass, and engineered it to produce ethanol. Here we report the direct conversion of switchgrass, a nonfood, renewable feedstock, to ethanol without conventional pretreatment of the biomass. This process was accomplished by deletion of lactate dehydrogenase and heterologous expression of a Clostridium thermocellum bifunctional acetaldehyde/alcohol dehydrogenase. Whereas wild-type C. bescii lacks the ability to make ethanol, 70% of the fermentation products in the engineered strain were ethanol [12.8 mM ethanol directly from 2% (wt/vol) switchgrass, a real-world substrate] with decreased production of acetate by 38% compared with wild-type. Direct conversion of biomass to ethanol represents a new paradigm for consolidated bioprocessing, offering the potential for carbon neutral, cost-effective, sustainable fuel production.

Renewable Energy Production from DoD Installation Solid Wastes by Anaerobic Digestion

DTIC Science & Technology

2016-06-01

ENGINEERING GUIDANCE REPORT Renewable Energy Production from DoD Installation Solid Wastes by Anaerobic Digestion ESTCP Project ER-200933 JUNE...Defense. Page Intentionally Left Blank Renewable Energy Production From DoD Installation Solid Wastes by Anaerobic Digestion ii June 2016 REPORT...3. DATES COVERED (2009 – 2016) 4. TITLE AND SUBTITLE Renewable Energy Production from DoD Installation Solid Wastes by Anaerobic Digestion 5a

Comparison of Leachate Quality from Aerobic and Anaerobic Municipal Solid Waste Bioreactors

NASA Astrophysics Data System (ADS)

Borglin, S. E.; Hazen, T. C.; Oldenburg, C. M.

2002-12-01

Municipal solid waste landfills are becoming a drain on the resources of local municipalities as the requirements for stabilization and containment become increasingly stringent. Current regulations limit the moisture in the landfill to minimize leachate production and lower the potential for release of leachate to the environment. Recent research has shown that addition and recycling of moisture in the waste optimizes the biodegradation of stabilization and also provides a means for leachate treatment. This study compares the characteristics of leachate produced from aerobic and anaerobic laboratory bioreactors, and leachate collected from a full-scale anaerobic bioreactor. The laboratory reactors consisted of 200-liter tanks filled with fresh waste materials with the following conditions: (a) aerobic (air injection with leachate recirculation), (b) anaerobic (leachate recirculation). The leachate from the reactors was monitored for metals, nutrients, organic carbon, and microbiological activity for up to 500 days. Leachate from the aerobic tank had significantly lower concentrations of all potential contaminants, both organic and metal, after only a few weeks of operation. Metals leaching was low throughout the test period for the aerobic tanks, and decreased over time for the anaerobic tanks. Organic carbon as measured by BOD, COD, TOC, and COD were an order of magnitude higher in the leachate from the anaerobic system. Microbiological assessment by lipid analysis, enzyme activity assays, and cell counts showed high biomass and diversity in both the aerobic and anaerobic bioreactors, with higher activity in the anaerobic leachate. Results from the full-scale anaerobic bioreactor were not significantly different from those of the laboratory anaerobic bioreactor. The reduction in noxious odors was a significant advantage of the aerobic system. These results suggest that aerobic management of landfills could reduce or eliminate the need for leachate treatment

Multicenter Study of Antimicrobial Susceptibility of Anaerobic Bacteria in Korea in 2012

PubMed Central

Lee, Yangsoon; Park, Yeon-Joon; Kim, Mi-Na; Uh, Young; Kim, Myung Sook

2015-01-01

Background Periodic monitoring of regional or institutional resistance trends of clinically important anaerobic bacteria is recommended, because the resistance of anaerobic pathogens to antimicrobial drugs and inappropriate therapy are associated with poor clinical outcomes. There has been no multicenter study of clinical anaerobic isolates in Korea. We aimed to determine the antimicrobial resistance patterns of clinically important anaerobes at multiple centers in Korea. Methods A total of 268 non-duplicated clinical isolates of anaerobic bacteria were collected from four large medical centers in Korea in 2012. Antimicrobial susceptibility was tested by the agar dilution method according to the CLSI guidelines. The following antimicrobials were tested: piperacillin, piperacillin-tazobactam, cefoxitin, cefotetan, imipenem, meropenem, clindamycin, moxifloxacin, chloramphenicol, metronidazole, and tigecycline. Results Organisms of the Bacteroides fragilis group were highly susceptible to piperacillin-tazobactam, imipenem, and meropenem, as their resistance rates to these three antimicrobials were lower than 6%. For B. fragilis group isolates and anaerobic gram-positive cocci, the resistance rates to moxifloxacin were 12-25% and 11-13%, respectively. Among B. fragilis group organisms, the resistance rates to tigecycline were 16-17%. Two isolates of Finegoldia magna were non-susceptible to chloramphenicol (minimum inhibitory concentrations of 16-32 mg/L). Resistance patterns were different among the different hospitals. Conclusions Piperacillin-tazobactam, cefoxitin, and carbapemems are highly active β-lactam agents against most of the anaerobes. The resistance rates to moxifloxacin and tigecycline are slightly higher than those in the previous study. PMID:26206683

Anaerobic biodegradation of 8:2 fluorotelomer alcohol in anaerobic activated sludge: Metabolic products and pathways.

PubMed

Li, Fei; Su, Qiangfa; Zhou, Zhenming; Liao, Xiaobin; Zou, Jing; Yuan, Baoling; Sun, Wenjie

2018-06-01

The anaerobic biodegradability and metabolic pathways of 8:2 fluorotelomer alcohol (8:2 FTOH) were investigated in anaerobic activated sludge. The biodegradation was well described by a double exponential decay model. 8:2 FTOH was biodegraded to poly- and perfluorinated metabolites with the release of fluoride ion. All polyfluorinated metabolites were intermediate metabolic products and could be further transformed to other metabolites, while perfluorinated metabolites were terminal products. 2H-perfluoro-2-decenoic acid (8:2 FTUA) and perfluorooctanoic acid (PFOA) were verified as the most abundant poly- and perfluorinated metabolites, respectively. Two shorter-chain perfluorinated metabolites, perfluoropentanoic acid (PFPeA) and perfluorobutyric acid (PFBA), were first reported in the biodegradation of 8:2 FTOH. However, the total molar recovery of 8:2 FTOH decreased with increasing incubation time, indicating that there might be some unknown metabolites. Thus, the anaerobic biodegradation pathways were proposed as follows: 8:2 FTOH was oxidized to 8:2 FTUA and 2-perfluorooctyl ethanoic acid (8:2 FTCA) via 2-perfluorooctyl acetaldehyde (8:2 FTAL), and then 8:2 FTUA and 8:2 FTCA were further transformed to 1-perfluoroheptyl ethanol (7:2 sFTOH) via 3-perfluoroheptyl propionic acid (7:3 acid) or/and 3-perfluoroheptyl acrylic acid (7:3 Uacid), and eventually 7:2 sFTOH was further biodegraded to PFOA and other perfluorocarboxylates containing less than eight carbons. Copyright © 2018 Elsevier Ltd. All rights reserved.

Studies on the toxic effects of pentachlorophenol on the biological activity of anaerobic granular sludge.

PubMed

Liu, Xin-Wen; He, Ruo; Shen, Dong-Sheng

2008-09-01

In order to explore the pathway of the anaerobic biotreatment of the wastewater containing pentachlorophenol (PCP) and ensure the normal operation of Upflow Anaerobic Sludge Blanket (UASB) reactor, the anaerobic sludge under different acclimation conditions were selected to seed and start up UASB reactors. Anaerobic toxicity assays were employed to study the biological activity, the tolerance and the capacity to degrade PCP of different anaerobic granular sludge from UASB reactors. Results showed that the anaerobic granular sludge acclimated to chlorophenols (CPs) could degrade PCP more quickly (up to 9.50mg-PCP g(-1)TVS d(-1)). And the anaerobic granular sludge without acclimation to CPs had only a little activity of degrading PCP (less than 0.07 mg-PCP g(-1)TVS d(-1)). Different PCP concentrations (2, 4, 6, 8 mg L(-1)) had different inhibition effects on glucose utilization, volatile fatted acidity (VFA)-degrading and methanogens activity of PCP degradation anaerobic granular sludge, and the biological activity declined with the increase in PCP concentration. The methanogens activity suffered inhibition from PCP more easily. The different acclimation patterns of seeded sludge had distinctly different effects on biological activity of the degradation of PCP of anaerobic granular sludge from UASB reactors. The biological activity of the anaerobic granular sludge acclimated to PCP only was also inhibited. This inhibition was weak compared to that of anaerobic granular sludge acclimated to CPs, further, the activity could recover more quickly in this case. In the same reactor, the anaerobic granular sludge from the mid and base layers showed higher tolerance to PCP than that from super layer or if the sludge is unacclimated to CPs, and the corresponding recovery time of the biological activity in the mid and base layers were short. Acetate-utilizing methanogens and syntrophic propinate degraders were sensitive to PCP, compared to syntrophic butyrate degraders.

Kinetics of thermophilic anaerobes in fixed-bed reactors.

PubMed

Perez, M; Romero, L I; Sales, D

2001-08-01

The main objective of this study is to estimate growth kinetic constants and the concentration of "active" attached biomass in two anaerobic thermophilic reactors which contain different initial sizes of immobilized anaerobic mixed cultures and decompose distillery wastewater. This paper studies the substrate decomposition in two lab-scale fixed-bed reactors operating at batch conditions with corrugated tubes as support media. It can be demonstrated that high micro-organisms-substrate ratios favor the degradation activity of the different anaerobic cultures, allowing the stable operation without lag-phases and giving better quality in effluent. The kinetic parameters obtained--maximum specific growth rates (mu(max)), non-biodegradable substrate (S(NB)) and "active or viable biomass" concentrations (X(V0))--were obtained by applying the Romero kinetic model [L.I. Romero, 1991. Desarrollo de un modelo matemático general para los procesos fermentativos, Cinética de la degradación anaerobia, Ph.D. Thesis, University of Cádiz (Spain), Serv. Pub. Univ. Cádiz], with COD as substrate and methane (CH4) as the main product of the anaerobic process. This method is suitable to calculate and to differentiate the main kinetic parameters of both the total anaerobic mixed culture and the methanogenic population. Comparison of experimental measured concentration of volatile attached solids (VS(att)) in both reactors with the estimated "active" biomass concentrations obtained by applying Romero kinetic model [L.I. Romero, 1991. Desarrollo de un modelo matemático general para los procesos fermentativos, Cinética de la degradación anaerobia, Ph.D. Thesis, University of Cádiz (Spain), Serv. Pub. Univ. Cádiz] shows that a large amount of inert matter is present in the fixed-bed reactor.

Statistical Exposé of a Multiple-Compartment Anaerobic Reactor Treating Domestic Wastewater.

PubMed

Pfluger, Andrew R; Hahn, Martha J; Hering, Amanda S; Munakata-Marr, Junko; Figueroa, Linda

2018-06-01

  Mainstream anaerobic treatment of domestic wastewater is a promising energy-generating treatment strategy; however, such reactors operated in colder regions are not well characterized. Performance data from a pilot-scale, multiple-compartment anaerobic reactor taken over 786 days were subjected to comprehensive statistical analyses. Results suggest that chemical oxygen demand (COD) was a poor proxy for organics in anaerobic systems as oxygen demand from dissolved inorganic material, dissolved methane, and colloidal material influence dissolved and particulate COD measurements. Additionally, univariate and functional boxplots were useful in visualizing variability in contaminant concentrations and identifying statistical outliers. Further, significantly different dissolved organic removal and methane production was observed between operational years, suggesting that anaerobic reactor systems may not achieve steady-state performance within one year. Last, modeling multiple-compartment reactor systems will require data collected over at least two years to capture seasonal variations of the major anaerobic microbial functions occurring within each reactor compartment.

Promiscuous anaerobes: new and unconventional metabolism in methanogenic archaea.

PubMed

Grochowski, Laura L; White, Robert H

2008-03-01

The development of an oxygenated atmosphere on earth resulted in the polarization of life into two major groups, those that could live in the presence of oxygen and those that could not-the aerobes and the anaerobes. The evolution of aerobes from the earliest anaerobic prokaryotes resulted in a variety of metabolic adaptations. Many of these adaptations center on the need to sustain oxygen-sensitive reactions and cofactors to function in the new oxygen-containing atmosphere. Still other metabolic pathways that were not sensitive to oxygen also diverged. This is likely due to the physical separation of the organisms, based on their ability to live in the presence of oxygen, which allowed for the independent evolution of the pathways. Through the study of metabolic pathways in anaerobes and comparison to the more established pathways from aerobes, insight into metabolic evolution can be gained. This, in turn, can allow for extra- polation to those metabolic pathways occurring in the Last Universal Common Ancestor (LUCA). Some of the unique and uncanonical metabolic pathways that have been identified in the archaea with emphasis on the biochemistry of an obligate anaerobic methanogen, Methanocaldococcus jannaschii are reviewed.

Gram-positive anaerobic cocci--commensals and opportunistic pathogens.

PubMed

Murphy, Elizabeth Carmel; Frick, Inga-Maria

2013-07-01

Among the Gram-positive anaerobic bacteria associated with clinical infections, the Gram-positive anaerobic cocci (GPAC) are the most prominent and account for approximately 25-30% of all isolated anaerobic bacteria from clinical specimens. Still, routine culture and identification of these slowly growing anaerobes to the species level has been limited in the diagnostic laboratory, mainly due to the requirement of prolonged incubation times and time-consuming phenotypic identification. In addition, GPAC are mostly isolated from polymicrobial infections with known pathogens and therefore their relevance has often been overlooked. However, through improvements in diagnostic and in particular molecular techniques, the isolation and identification of individual genera and species of GPAC associated with specific infections have been enhanced. Furthermore, the taxonomy of GPAC has undergone considerable changes over the years, mainly due to the development of molecular identification methods. Existing species have been renamed and novel species have been added, resulting in changes of the nomenclature. As the abundance and significance of GPAC in clinical infections grow, knowledge of virulence factors and antibiotic resistance patterns of different species becomes more important. The present review describes recent advances of GPAC and what is known of the biology and pathogenic effects of Anaerococcus, Finegoldia, Parvimonas, Peptoniphilus and Peptostreptococcus, the most important GPAC genera isolated from human infections. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Assessment of hydrogen metabolism in commercial anaerobic digesters.

PubMed

Kern, Tobias; Theiss, Juliane; Röske, Kerstin; Rother, Michael

2016-05-01

Degradation of biomass in the absence of exogenous electron acceptors via anaerobic digestion involves a syntrophic association of a plethora of anaerobic microorganisms. The commercial application of this process is the large-scale production of biogas from renewable feedstock as an alternative to fossil fuels. After hydrolysis of polymers, monomers are fermented to short-chain fatty acids and alcohols, which are further oxidized to acetate. Carbon dioxide, molecular hydrogen (H2), and acetate generated during the process are converted to methane by methanogenic archaea. Since many of the metabolic pathways as well as the syntrophic interactions and dependencies during anaerobic digestion involve formation, utilization, or transfer of H2, its metabolism and the methanogenic population were assessed in various samples from three commercial biogas plants. Addition of H2 significantly increased the rate of methane formation, which suggested that hydrogenotrophic methanogenesis is not a rate-limiting step during biogas formation. Methanoculleus and Methanosarcina appeared to numerically dominate the archaeal population of the three digesters, but their proportion and the Bacteria-to-Archaea ratio did not correlate with the methane productivity. Instead, hydrogenase activity in cell-free extracts from digester sludge correlated with methane productivity in a positive fashion. Since most microorganisms involved in biogas formation contain this activity, it approximates the overall anaerobic metabolic activity and may, thus, be suitable for monitoring biogas reactor performance.

An active principle of Nigella sativa L., thymoquinone, showing significant antimicrobial activity against anaerobic bacteria.

PubMed

Randhawa, Mohammad Akram; Alenazy, Awwad Khalaf; Alrowaili, Majed Gorayan; Basha, Jamith

2017-01-01

Thymoquinone (TQ) is the major active principle of Nigella sativa seed (black seed) and is known to control many fungi, bacteria, and some viruses. However, the activity of TQ against anaerobic bacteria is not well demonstrated. Anaerobic bacteria can cause severe infections, including diarrhea, aspiration pneumonia, and brain abscess, particularly in immunodeficient individuals. The present study aimed to investigate the in vitro antimicrobial activity of TQ against some anaerobic pathogens in comparison to metronidazole. Standard, ATCC, strains of four anaerobic bacteria ( Clostridium difficile , Clostridium perfringens , Bacteroides fragilis , and Bacteroides thetaiotaomicron ), were initially isolated on special Brucella agar base (with hemin and vitamin K). Then, minimum inhibitory concentrations (MICs) of TQ and metronidazole were determined against these anaerobes when grown in Brucella agar, using serial agar dilution method according to the recommended guidelines for anaerobic organisms instructed by the Clinical and Laboratory Standards Institute. TQ showed a significant antimicrobial activity against anaerobic bacteria although much weaker than metronidazole. MICs of TQ and metronidazole against various anaerobic human pathogens tested were found to be between 10-160 mg/L and 0.19-6.25 mg/L, respectively. TQ controlled the anaerobic human pathogenic bacteria, which supports the use of N. sativa in the treatment of diarrhea in folk medicine. Further investigations are in need for determination of the synergistic effect of TQ in combination with metronidazole and the activity of derivatives of TQ against anaerobic infections.

High performance biological methanation in a thermophilic anaerobic trickle bed reactor.

PubMed

Strübing, Dietmar; Huber, Bettina; Lebuhn, Michael; Drewes, Jörg E; Koch, Konrad

2017-12-01

In order to enhance energy efficiency of biological methanation of CO 2 and H 2 , this study investigated the performance of a thermophilic (55°C) anaerobic trickle bed reactor (ATBR) (58.1L) at ambient pressure. With a methane production rate of up to 15.4m 3 CH4 /(m 3 trickle bed ·d) at methane concentrations above 98%, the ATBR can easily compete with the performance of other mixed culture methanation reactors. Control of pH and nutrient supply turned out to be crucial for stable operation and was affected significantly by dilution due to metabolic water production, especially during demand-orientated operation. Considering practical applications, inoculation with digested sludge, containing a diverse biocenosis, showed high adaptive capacity due to intrinsic biological diversity. However, no macroscopic biofilm formation was observed at thermophilic conditions even after 313days of operation. The applied approach illustrates the high potential of thermophilic ATBRs as a very efficient energy conversion and storage technology. Copyright © 2017 Elsevier Ltd. All rights reserved.

Anaerobic bioconversion of organic waste into biogas by hot water treatment at near-critical conditions: application in bioregenerative life support.

PubMed

Lissens, Geert; Verstraete, Willy; Albrecht, Tobias; Brunner, Gerd; Lasseur, Christophe

2003-01-01

The feasibility of nearly-complete conversion of lignocellulosic waste (70% food crops, 20% faecal matter and 10% green algae) into biogas was investigated in the context of a Life Support Project. The treatment comprised a series of processes, i.e. a mesophilic laboratory scale CSTR (continuously stirred tank reactor), an upflow biofilm reactor and a hydrothermolysis system in near-critical water. By the one-stage CSTR, a biogas yield of 75% with a specific biogas production of 0.37 l biogas g(-1) VSS (volatile suspended solids) added at a HRT (hydraulic retention time) of 20 d was obtained. Biogas yields further increased with 10-15% at HRT > 20 d, indicating the hydrolysis of lignocellulose to be the rate-limiting conversion step. The solids present in the CSTR-effluent were subsequently treated by hot water treatment (T approximately 310-350 degrees C, p approximately 240 bar), resulting in effective carbon liquefaction (50-60% without and 83% with carbon dioxide saturation) and complete hygienisation of the residue. Subsequent anaerobic digestion of the hydrolysate allowed further conversion of 48-60% on COD (chemical oxygen demand) basis. Thus, the total process yielded biogas corresponding with a COD conversion up to 90% of the original organic matter. It appears that mesophilic digestion in conjunction with hydrothermolysis at near-critical conditions offers interesting features for (nearly) complete, non-toxic and hygienic carbon and energy recovery from human waste in a bioregenerative life support context.

Anaerobic Fungi: A Potential Source of Biological H2 in the Oceanic Crust

PubMed Central

Ivarsson, Magnus; Schnürer, Anna; Bengtson, Stefan; Neubeck, Anna

2016-01-01

The recent recognition of fungi in the oceanic igneous crust challenges the understanding of this environment as being exclusively prokaryotic and forces reconsiderations of the ecology of the deep biosphere. Anoxic provinces in the igneous crust are abundant and increase with age and depth of the crust. The presence of anaerobic fungi in deep-sea sediments and on the seafloor introduces a type of organism with attributes of geobiological significance not previously accounted for. Anaerobic fungi are best known from the rumen of herbivores where they produce molecular hydrogen, which in turn stimulates the growth of methanogens. The symbiotic cooperation between anaerobic fungi and methanogens in the rumen enhance the metabolic rate and growth of both. Methanogens and other hydrogen-consuming anaerobic archaea are known from subseafloor basalt; however, the abiotic production of hydrogen is questioned to be sufficient to support such communities. Alternatively, biologically produced hydrogen could serve as a continuous source. Here, we propose anaerobic fungi as a source of bioavailable hydrogen in the oceanic crust, and a close interplay between anaerobic fungi and hydrogen-driven prokaryotes. PMID:27433154

Step length and individual anaerobic threshold assessment in swimming.

PubMed

Fernandes, R J; Sousa, M; Machado, L; Vilas-Boas, J P

2011-12-01

Anaerobic threshold is widely used for diagnosis of swimming aerobic endurance but the precise incremental protocols step duration for its assessment is controversial. A physiological and biomechanical comparison between intermittent incremental protocols with different step lengths and a maximal lactate steady state (MLSS) test was conducted. 17 swimmers performed 7×200, 300 and 400 m (30 s and 24 h rest between steps and protocols) in front crawl until exhaustion and an MLSS test. The blood lactate concentration values ([La-]) at individual anaerobic threshold were 2.1±0.1, 2.2±0.2 and 1.8±0.1 mmol.l - 1 in the 200, 300 and 400 m protocols (with significant differences between 300 and 400 m tests), and 2.9±1.2 mmol.l - 1 at MLSS (higher than the incremental protocols); all these values are much lower than the traditional 4 mmol.l - 1 value. The velocities at individual anaerobic threshold obtained in incremental protocols were similar (and highly related) to the MLSS, being considerably lower than the velocity at 4 mmol.l - 1. Stroke rate increased and stroke length decreased throughout the different incremental protocols. It was concluded that it is valid to use intermittent incremental protocols of 200 and 300 m lengths to assess the swimming velocity corresponding to individual anaerobic threshold, the progressive protocols tend to underestimate the [La-] at anaerobic threshold assessed by the MLSS test, and swimmers increase velocity through stroke rate increases. © Georg Thieme Verlag KG Stuttgart · New York.

Estimation of Anaerobic Debromination Rate Constants of PBDE Pathways Using an Anaerobic Dehalogenation Model.

PubMed

Karakas, Filiz; Imamoglu, Ipek

2017-04-01

This study aims to estimate anaerobic debromination rate constants (k m ) of PBDE pathways using previously reported laboratory soil data. k m values of pathways are estimated by modifying a previously developed model as Anaerobic Dehalogenation Model. Debromination activities published in the literature in terms of bromine substitutions as well as specific microorganisms and their combinations are used for identification of pathways. The range of estimated k m values is between 0.0003 and 0.0241 d -1 . The median and maximum of k m values are found to be comparable to the few available biologically confirmed rate constants published in the literature. The estimated k m values can be used as input to numerical fate and transport models for a better and more detailed investigation of the fate of individual PBDEs in contaminated sediments. Various remediation scenarios such as monitored natural attenuation or bioremediation with bioaugmentation can be handled in a more quantitative manner with the help of k m estimated in this study.

Energetic and biochemical valorization of cork boiling wastewater by anaerobic digestion.

PubMed

Marques, Isabel Paula; Gil, Luís; La Cara, Francesco

2014-01-01

In addition to energy benefits, anaerobic digestion offers other interesting advantages. The cork industry is of great environmental, economic and social significance in the western Mediterranean region, with Portugal being the world-leading producer and exporter. Cork boiling wastewater (CBW) is a toxic and recalcitrant organic effluent produced by this sector, which constitutes a serious environmental hazard. However, there is no documented research on anaerobic treatment/valorization performed with this effluent. The work presented here was developed with the aim to use the anaerobic digestion process to convert the CBW polluting organic load into an energy carrier gas and valuable molecules for industry. No lag phases were observed and a methane yield of 0.126 to 0.142 m(3) kg(-1) chemical oxygen demand (COD)added was registered in the mesophilic consortium experiments carried out in batch flasks at 37 ± 1°C. Anaerobic digestion can be advantageously connected to ultrafiltration or electrochemical processes, due to the following: 1) reduction of ellagic acid content and consequent decrease of CBW viscosity; and 2) increase in conductivity after the anaerobic process, avoiding the electrolyte application of the electrochemical process. The improvement of several CBW biochemical features shows that anaerobic digestion may provide additionally useful molecules. The rise in concentration of some of these compounds, belonging to the benzoic acid family (gallic, protocatechuic, vanillic and syringic acids), is responsible for the increase of antiradical activity of the phenolic fraction. Additionally, some enzymatic activity was also observed and while the laccase activity increased in the digested effluent by anaerobiosis, xylanase was formed in the process. The multidisciplinary approach adopted allowed the valorization of CBW in terms of energy and valuable biomolecules. By exploiting the anaerobic digestion process potential, a novel methodology to toxic