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Sample records for anaerobic cometabolic conversion

  1. Co-metabolic conversion of toluene in anaerobic n-alkane-degrading bacteria.

    PubMed

    Rabus, Ralf; Jarling, René; Lahme, Sven; Kühner, Simon; Heider, Johann; Widdel, Friedrich; Wilkes, Heinz

    2011-09-01

    Diverse microorganisms have been described to degrade petroleum hydrocarbons anaerobically. Strains able to utilize n-alkanes do not grow with aromatic hydrocarbons, whereas strains able to utilize aromatic hydrocarbons do not grow with n-alkanes. To investigate this specificity in more detail, three anaerobic n-alkane degraders (two denitrifying, one sulfate-reducing) and eight anaerobic alkylbenzene degraders (five denitrifying, three sulfate-reducing) were incubated with mixtures of n-alkanes and toluene. Whereas the toluene degradationers formed only the characteristic toluene-derived benzylsuccinate and benzoate, but no n-alkane-derived metabolites, the n-alkane degraders formed toluene-derived benzylsuccinate, 4-phenylbutanoate, phenylacetate and benzoate besides the regular n-alkane-derived (1-methylalkyl)succinates and methyl-branched alkanoates. The co-metabolic conversion of toluene by anaerobic n-alkane degraders to the level of benzoate obviously follows the anaerobic n-alkane degradation pathway with C-skeleton rearrangement and decarboxylation rather than the β-oxidation pathway of anaerobic toluene metabolism. Hence, petroleum-derived aromatic metabolites detectable in anoxic environments may not be exclusively formed by genuine alkylbenzene degraders. In addition, the hitherto largely unexplored fate of fumarate hydrogen during the activation reactions was examined with (2,3-(2) H(2) )fumarate as co-substrate. Deuterium was completely exchanged with hydrogen at the substituted carbon atom (C-2) of the succinate adducts of n-alkanes, whereas it is retained in toluene-derived benzylsuccinate, regardless of the type of enzyme catalysing the fumarate addition reaction.

  2. PAH fate during the anaerobic digestion of contaminated sludge: Do bioavailability and/or cometabolism limit their biodegradation?

    PubMed

    Barret, M; Carrère, H; Delgadillo, L; Patureau, D

    2010-07-01

    The anaerobic removal of 13 Polycyclic Aromatic Hydrocarbons (PAHs) was measured in five continuous anaerobic digestors with different feed sludge, in which abiotic losses were neglected. These feeds were chosen to generate different levels of PAH bioavailability and cometabolism within the reactors. Based on the accurate modelling of PAH sorption in sludge, the aqueous fraction (including free and sorbed-to-dissolved-and-colloidal-matter PAHs) was demonstrated to be bioavailable, which validated a widespread assumption about micropollutants bioavailability in sludge. It was also demonstrated that bioavailability is not the only influencing factor. Indeed, PAHs biodegradation resulted from a combination of bioavailability and cometabolism. An equation adapted from Criddle (1993, The Kinetics of Cometabolism. Biotechnology and Bioengineering 41, 1048-1056) that takes into account both mechanisms was shown to fit the experimental data, with dry matter removal rate identified as the criteria for cometabolism. The existence of a threshold of dry matter cometabolism was suggested, below which PAHs removal would not be possible. The parameters of the Criddle equation were demonstrated to depend on PAH molecular structure, and the results suggest that they would also be influenced by substrate composition and microbial population. This research provided original outcomes for the assessment of micropollutants fate. Indeed, the understanding of the driving mechanisms was improved, which has implications for the optimization of micropollutants removal.

  3. Anaerobic cometabolic transformation of polycyclic and heterocyclic aromatic hydrocarbons: evidence from laboratory and field studies

    SciTech Connect

    Michael Safinowski; Christian Griebler; Rainer U. Meckenstock

    2006-07-01

    The sulfate-reducing enrichment culture N47 can grow on naphthalene or 2-methylnaphthalene as the sole carbon and energy source. The study reported shows that the culture can furthermore cometabolically transform a variety of polycyclic and heteroaromatic compounds with naphthalene or methylnaphthalene as the auxiliary substrate. Most of the cosubstrates were converted to the corresponding carboxylic acids, frequently to several isomers. The mass spectra of specific metabolites that were extracted from supernatants of cultures containing the cosubstrates benzothiophene, benzofuran, and 1-methylnaphthalene resembled known intermediates of the anaerobic naphthalene and 2-methylnaphthalene degradation pathways. This indicates that some of the tested compounds were first methylated and then transformed to the corresponding methylsuccinic acids by a fumarate addition to the methyl group. For some of the cosubstrates, a partial or total inhibition of growth on the auxiliary substrate was observed. This was caused by a specific combination of auxiliary substrate and cosubstrate. None of the cosubstrates tested could be utilized as the sole carbon source and electron donor by the enrichment culture N47. Field investigations at the tar-oil-contaminated aquifer (at a former gasworks in southwest Germany), where strain N47 originated, revealed the presence of metabolites similar to the ones identified in batch culture supernatants. The findings suggest that aromatic hydrocarbons and heterocyclic compounds can be converted by aquifer organisms and produce a variety of polar compounds that become mobile in groundwater. 51 refs., 4 figs., 2 tabs.

  4. Hemicellulose conversion by anaerobic digestion

    SciTech Connect

    Ghosh, S.; Henry, M.P.; Christopher, R.W.

    1982-01-01

    The digestibility of an aquatic biomass (water hyacinth), a land-based biomass (Coastal Bermuda grass), and a biomass-waste blend (a mixture of hyacinth, grass, MSW, and sludge) under various digestion conditions was studied. Anaerobic digestion of hemicellulose consists of the steps of enzymatic hydrolysis of hemicellulose to glucans, mannans, galactans, xylans, and arabans, and then to simple hexose and pentose sugars; production of C/sub 2/ and higher fatty acids from the simple sugars; conversion of higher fatty acids to acetate; and finally, production of methane and CO/sub 2/ from acetate, and CO/sub 2/ and hydrogen. The conversion of hemicellulose was higher under mesophilic conditions than those of cellulose or protein for all biomass test feeds, probably because the hemicellulose structure was more vulnerable to enzymatic attack than that of the lignocellulosic component. Cellulose conversion efficiencies at the mesophilic and thermophilic temperatures were about the same. However, hemicellulose was converted at a much lower efficiency than cellulose during thermophilic digestion - a situation that was the reverse of that observed at the mesophilic temperature. Cellulose was utilized in preference to hemicellulose during mesophilic digestion of nitrogen-supplemented Bermuda grass. It was speculated that Bermuda grass cellulose was converted at a higher efficiency than hemicellulose in the presence of external nitrogen because the metabolism of the breakdown product (glucose) of cellulose requires the least investment of enzymes and energy.

  5. Cometabolic bioremediation

    SciTech Connect

    Hazen, Terry C.

    2009-02-15

    Cometabolic bioremediation is probably the most under appreciated bioremediation strategy currently available. Cometabolism strategies stimulate only indigenous microbes with the ability to degrade the contaminant and cosubstrate e.g. methane, propane, toluene and others. This highly targeted stimulation insures that only those microbes that can degrade the contaminant are targeted, thus reducing amendment costs, well and formation plugging, etc. Cometabolic bioremediation has been used on some of the most recalcitrant contaminants, e.g. PCE, TCE, MTBE, TNT, dioxane, atrazine, etc. Methanotrophs have been demonstrated to produce methane monooxygense, an oxidase that can degrade over 300 compounds. Cometabolic bioremediation also has the advantage of being able to degrade contaminants to trace concentrations, since the biodegrader is not dependent on the contaminant for carbon or energy. Increasingly we are finding that in order to protect human health and the environment that we must remediate to lower and lower concentrations, especially for compounds like endocrine disrupters, thus cometabolism may be the best and maybe the only possibility that we have to bioremediate some contaminants.

  6. Enzyme Systems of Anaerobes for Biomass Conversion.

    PubMed

    Munir, Riffat; Levin, David B

    Biofuels from abundantly available cellulosic biomass are an attractive alternative to current petroleum-based fuels (fossil fuels). Although several strategies exist for commercial production of biofuels, conversion of biomass to biofuels via consolidated bioprocessing offers the potential to reduce production costs and increase processing efficiencies. In consolidated bioprocessing (CBP), enzyme production, cellulose hydrolysis, and fermentation are all carried out in a single-step by microorganisms that efficiently employ a multitude of intricate enzymes which act synergistically to breakdown cellulose and its associated cell wall components. Various strategies employed by anaerobic cellulolytic bacteria for biomass hydrolysis are described in this chapter. In addition, the regulation of CAZymes, the role of "omics" technologies in assessing lignocellulolytic ability, and current strategies for improving biomass hydrolysis for optimum biofuel production are highlighted.

  7. Co-metabolism.

    PubMed

    Dalton, H; Stirling, D I

    1982-06-11

    There have been numerous instances reported when potentially recalcitrant compounds have been modified by microorganisms or completely mineralized by mixed communities or organisms; an example is pesticide biodegradation. Both situations rely upon the ability of microorganisms to transform compounds that they cannot utilize as sole sources of carbon and energy. This phenomenon of co-oxidation or co-metabolism has been fraught with confusion for many years as a result of the ambiguous use of terms and definitions. A redefinition of co-metabolism is proposed in an attempt to alleviate the problem: Co-metabolism--the transformation of a non-growth substrate in the obligate presence of a growth substrate or another transformable compound. The term 'non-growth substrate' describes compounds that are unable to support cell replication as opposed to an increase in biomass. This definition was devised primarily as a result of non-growth substrate metabolism studies with methane-utilizing bacteria. These studies are described in the text. The possible impact of endogenous polymer reserves on co-metabolic events is discussed. A number of examples where non-growth substrate metabolism is of environmental importance are presented, in particular the potential role of methane-oxidizing bacteria in the removal of CO from the environment. The evolutionary significance, if any, of fortuitous metabolism or co-metabolism is discussed, as are potential applications of these phenomena.

  8. Low vacuum thermochemical conversion of anaerobically digested swine solids.

    PubMed

    Bergier, Ivan; Vinhal-Freitas, Isabel; Guiotoku, Marcela

    2013-07-01

    This work provides data on the production of biochar from the pyrolysis of the solid phase of swine effluents following anaerobic biodigestion. The study involved the low vacuum thermochemical conversion by environmental scanning electron microscope (ESEM) in a thermoregulated hot-stage tungsten SEM. The feedstock was characterized by FTIR, ESEM and energy dispersive X-ray analysis (EDS). The charred feedstock at peak temperatures of 300°C, 400°C, 500°C, 600°C, 700°C, and 1000°C were assessed by SEM and EDS. For each pyrolysis experiment, the exhaust gases were monitored by photoacoustic spectroscopy. SEM/EDS indicated that for increasing peak temperature in low vacuum pyrolysis, the mass losses are greater and the proportion of mineral particles such as P, Ca and Mg in the biochar. Photoacoustic spectroscopy showed that low vacuum pyrolysis is responsible for emissions of toxic gases NH3 and SO2 and radiative trace gases, especially N2O above 600°C. Copyright © 2013 Elsevier Ltd. All rights reserved.

  9. Anaerobic batch conversion of pine wood torrefaction condensate.

    PubMed

    Doddapaneni, Tharaka Rama Krishna C; Praveenkumar, Ramasamy; Tolvanen, Henrik; Palmroth, Marja R T; Konttinen, Jukka; Rintala, Jukka

    2017-02-01

    Organic compound rich torrefaction condensate, owing to their high water content and acidic nature, have yet to be exploited for practical application. In this study, microbial conversion of torrefaction condensate from pine wood through anaerobic batch digestion (AD) to produce methane was evaluated. Torrefaction condensate exhibited high methane potentials in the range of 430-492mL/g volatile solids (VS) and 430-460mL/gVS under mesophilic and thermophilic conditions, respectively. Owing to the changes in the composition, the methane yields differed with the torrefaction condensates produced at different temperatures (225, 275 and 300°C), with a maximum of 492±18mL/gVS with the condensate produced at 300°C under mesophilic condition. The cyclic batch AD experiments showed that 0.1VSsubstrate:VSinoculum is optimum, whereas the higher substrate loading (0.2-0.5) resulted in a reversible inhibition of the methane production. The results suggest that torrefaction condensate could be practically valorized through AD.

  10. Design Of Bioremediation Systems For Groundwater (Aerobic and Anaerobic Plus Representative Case Studies)

    EPA Science Inventory

    The attached presentation discusses the fundamentals of bioremediation in the subsurface. The basics of aerobic, cometabolic, and anaerobic bioremediation are presented. Case studies from the Delaware Sand & Gravel Superfund Site, Dover Cometabolic Research Project and the SABR...

  11. Design Of Bioremediation Systems For Groundwater (Aerobic and Anaerobic Plus Representative Case Studies)

    EPA Science Inventory

    The attached presentation discusses the fundamentals of bioremediation in the subsurface. The basics of aerobic, cometabolic, and anaerobic bioremediation are presented. Case studies from the Delaware Sand & Gravel Superfund Site, Dover Cometabolic Research Project and the SABR...

  12. Final Project Report - Coupled Biogeochemical Process Evaluation for Conceptualizing Trichloriethylene Co-Metabolism: Co-Metabolic Enzyme Activity Probes and Modeling Co-Metabolism and Attenuation

    SciTech Connect

    Starr, Robert C; Orr, Brennon R; Lee, M Hope; Delwiche, Mark

    2010-02-26

    Trichloroethene (TCE) (also known as trichloroethylene) is a common contaminant in groundwater. TCE is regulated in drinking water at a concentration of 5 µg/L, and a small mass of TCE has the potential to contaminant large volumes of water. The physical and chemical characteristics of TCE allow it to migrate quickly in most subsurface environments, and thus large plumes of contaminated groundwater can form from a single release. The migration and persistence of TCE in groundwater can be limited by biodegradation. TCE can be biodegraded via different processes under either anaerobic or aerobic conditions. Anaerobic biodegradation is widely recognized, but aerobic degradation is less well recognized. Under aerobic conditions, TCE can be oxidized to non hazardous conditions via cometabolic pathways. This study applied enzyme activity probes to demonstrate that cometabolic degradation of TCE occurs in aerobic groundwater at several locations, used laboratory microcosm studies to determine aerobic degradation rates, and extrapolated lab-measured rates to in situ rates based on concentrations of microorganisms with active enzymes involved in cometabolic TCE degradation. Microcosms were constructed using basalt chips that were inoculated with microorganisms to groundwater at the Idaho National Laboratory Test Area North TCE plume by filling a set of Flow-Through In Situ Reactors (FTISRs) with chips and placing the FTISRs into the open interval of a well for several months. A parametric study was performed to evaluate predicted degradation rates and concentration trends using a competitive inhibition kinetic model, which accounts for competition for enzyme active sites by both a growth substrate and a cometabolic substrate. The competitive inhibition kinetic expression was programmed for use in the RT3D reactive transport package. Simulations of TCE plume evolution using both competitive inhibition kinetics and first order decay were performed.

  13. Applications of a simulation model to description of anaerobic conversion of complex organic matter into methane

    SciTech Connect

    Vavilin, V.A.; Rytow, S.V.; Lokshina, L.Ya.

    1996-12-31

    Three years passed since the generalized model of anaerobic degradation of complex organic matter has been developed. Now the new modifications were created. Anaerobic degradation was described as a multistep process of series and parallel reactions in which several groups of bacteria take part. Hydrolysis, acidogenesis, acetogenesis and methanogenesis were considered in the model with the various kinetic functions. A two-phase equation describing a particulate substrate degradation as a heterogeneous reaction has been developed. Acetic, butyric, and propionic groups of acidogenic bacteria producing the particular products were considered. The additional group of homoacetogenic bacteria producing acetate from hydrogen and carbon dioxide was involved into new version of the model. Ammonia and hydrogen sulfide inhibition were described previously. In that paper, it was shown by simulation of several case-studies that unionized volatile fatty acids (VFA) are the inhibitors of key stages of anaerobic conversion of complex organic matter: hydrolysis, acetogenesis and methanogenesis.

  14. Anaerobic

    MedlinePlus

    ... more prolonged exercise like walking or jogging. Anaerobic reactions are faster. We need them during shorter, more intense activities like sprinting. Anaerobic exercise leads to a buildup of lactic acid in our tissues. We need oxygen to remove ...

  15. Monochloramine Cometabolism by Mixed-Culture Nitrifiers ...

    EPA Pesticide Factsheets

    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 experiment: (1) a positive control to estimate ammonia kinetic parameters, (2) a negative control to account for abiotic reactions, and (3) a cometabolism reactor to estimate cometabolism kinetic constants. Kinetic parameters were estimated in AQUASIM with a simultaneous fit to all experimental data. Cometabolism kinetics were best described by a first order model. Monochloramine cometabolism kinetics were similar to those of ammonia metabolism, and monochloramine cometabolism was a significant loss mechanism (30% of the observed monochloramine loss). These results demonstrated that monochloramine cometabolism occurred in mixed cultures similar to those found in drinking water distribution systems; thus, cometabolism may be a significant contribution to monochloramine loss during nitrification episodes in drinking water distribution systems. The results demonstrated that monochloramine cometabolism occurred in mixed cultures similar to those found in drinking water distribution systems; thus, cometabolism may be a significant contribution to monochloramine loss during nitrification episodes in drinking water distribution systems.

  16. Anaerobic conversion of microalgal biomass to sustainable energy carriers--a review.

    PubMed

    Lakaniemi, Aino-Maija; Tuovinen, Olli H; Puhakka, Jaakko A

    2013-05-01

    This review discusses anaerobic production of methane, hydrogen, ethanol, butanol and electricity from microalgal biomass. The amenability of microalgal biomass to these bioenergy conversion processes is compared with other aquatic and terrestrial biomass sources. The highest energy yields (kJ g(-1) dry wt. microalgal biomass) reported in the literature have been 14.8 as ethanol, 14.4 as methane, 6.6 as butanol and 1.2 as hydrogen. The highest power density reported from microalgal biomass in microbial fuel cells has been 980 mW m(-2). Sequential production of different energy carriers increases attainable energy yields, but also increases investment and maintenance costs. Microalgal biomass is a promising feedstock for anaerobic energy conversion processes, especially for methanogenic digestion and ethanol fermentation. The reviewed studies have mainly been based on laboratory scale experiments and thus scale-up of anaerobic utilization of microalgal biomass for production of energy carriers is now timely and required for cost-effectiveness comparisons.

  17. 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.

  18. High-rate anaerobic wastewater treatment: diversifying from end-of-the-pipe treatment to resource-oriented conversion techniques.

    PubMed

    van Lier, Jules B

    2008-01-01

    Decades of developments and implementations in the field of high-rate anaerobic wastewater treatment have put the technology at a competitive level. With respect to sustainability and cost-effectiveness, anaerobic treatment has a much better score than many alternatives. Particularly, the energy conservation aspect, i.e. avoiding the loss of energy for destruction of organic matter, while energy is reclaimed from the organic waste constituents in the form of biogas, was an important driver in the development of such systems. Invoked by the present greenhouse alert, the energy involved is nowadays translated into carbon credits, providing another incentive to further implement anaerobic technology. Anaerobic conversion processes, however, offer much more than cost-effective treatment systems. Selective recovery of metals, effective desulphurization, recovery of nutrients, reductive detoxification, and anaerobic oxidation of specific compounds are examples of the potentials of anaerobic treatment. This paper presents a survey on the state of the art of full-scale anaerobic high-rate treatment of industrial wastewaters and highlights current trends in anaerobic developments. (c) IWA Publishing 2008.

  19. Kinetics of Aerobic Cometabolism of Chlorinated Solvents

    DTIC Science & Technology

    1998-07-01

    used to describe the cometabolic degradation of 4-chlorophenol in the presence of phenol by Pseudomonas put ida PpG4, an aromatic degrading... Pseudomonas cepacia G4, has shown the most rapid degradation kinetics, with a k1 for TCE that is comparable to that of M trichosporium OB3b. All mixed...competitive inhibition and cometabolism in the biodegradation of benzene, toluene, and p-xylene by two Pseudomonas isolates, Biotech. Bioeng. 41 : 1 057- 1

  20. Membrane bioreactor for TCE cometabolism with toluene

    SciTech Connect

    Dolasa, A.R.; Ergas, S.J.

    1999-07-01

    Biofilters have been of limited use for cometabolism of chlorinated organic compounds such as trichloroethylene (TCE). In cometabolism, cosubstrates must be available as primary carbon and energy sources and to induce synthesis of necessary enzymes to cometabolize the target compound. The cosubstrates often inhibit cometabolism of the target compound, however. A hollow fiber membrane bioreactor was investigated that allowed for addition of cosubstrates to the microbial population while maintaining low enough concentrations to prevent inhibition. The system involves a bundle of polypropylene fibers through which VOC contaminated air passes. The fibers are immersed in a recirculating nutrient/cosubstrate solution. This system is suited to cometabolism as the cosubstrate is diluted into the nutrient solution. A mixed culture of toluene degraders was developed from a municipal wastewater mixed liquor sample. Batch experiments were performed to determine whether the culture could cometabolize TCE, the toluene degradation rate kinetics and the extent of toluene and TCE inhibition. In batch experiments, TCE was cometabolized only after toluene was degraded. No inhibition or injury to the toluene degrading ability was observed at up to 15 mg/L toluene or up to 1.5 mg/L TCE. The culture was inoculated into the hollow-fiber membrane bioreactor. Initially toluene was supplied to the reactor at a concentration of 200 ppm to build a sufficient biomass density on the fibers. After steady-state toluene removal was achieved, a toluene-TCE mixture was added to the reactor. This paper investigates if addition of toluene to the reactor in gas or liquid phase is more favorable for cometabolism, the use of a pulsing strategy, and the benefits of including a simple biomass removal method.

  1. Monochloramine Cometabolism by Nitrifying Biofilm Relevant ...

    EPA Pesticide Factsheets

    Recently, biological monochloramine removal (i.e., cometabolism) by a pure culture ammonia–oxidizing bacteria, Nitrosomonas europaea, and a nitrifying mixed–culture have been shown to increase monochloramine demand. Although important, these previous suspended culture batch kinetic experiments were not representative of drinking water distribution systems where bacteria grow predominantly as biofilm attached to pipe walls or sediments and physiological differences may exist between suspension and biofilm growth. Therefore, the current research was an important next step in extending the previous results to investigate monochloramine cometabolism by biofilm grown in annular reactors under drinking water relevant conditions. Estimated monochloramine cometabolism kinetics were similar to those of ammonia metabolism, and monochloramine cometabolism was a significant loss mechanism (25–40% of the observed monochloramine loss). These results demonstrated that monochloramine cometabolism occurred in drinking water relevant nitrifying biofilm; thus, cometabolism may be a significant contribution to monochloramine loss during nitrification episodes in distribution systems. Investigate whether or not nitrifying biofilm can biologically transform monochloramine under drinking water relevant conditions.

  2. 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 CO2 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, CO2) substrates in a single organism, can overcome these constraints to increase product yields and reduce overall CO2 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, H2) is provided, the fermentation emits no CO2. Finally, we show that mixotrophy is a general trait among acetogens.

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

    PubMed Central

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

    2016-01-01

    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 CO2 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, CO2) substrates in a single organism, can overcome these constraints to increase product yields and reduce overall CO2 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, H2) is provided, the fermentation emits no CO2. Finally, we show that mixotrophy is a general trait among acetogens. PMID:27687501

  4. Elucidation of the pathways of catabolic glutamate conversion in three thermophilic anaerobic bacteria.

    PubMed

    Plugge, C M; van Leeuwen, J M; Hummelen, T; Balk, M; Stams, A J

    2001-07-01

    The glutamate catabolism of three thermophilic syntrophic anaerobes was compared based on the combined use of [(13)C] glutamate NMR measurements and enzyme activity determinations. In some cases the uptake of intermediates from different pathways was studied. The three organisms, Caloramator coolhaasii, Thermanaerovibrio acidaminovorans and strain TGO, had a different stoichiometry of glutamate conversion and were dependent on the presence of a hydrogen scavenger (Methanobacterium thermoautotrophicum Z245) to a different degree for their growth. C. coolhaasii formed acetate, CO(2), NH(4)(+) and H(2) from glutamate. Acetate was found to be formed through the beta-methylaspartate pathway in pure culture as well as in coculture. T. acidaminovorans converted glutamate to acetate, propionate, CO(2), NH(4)(+) and H(2). Most likely, this organism uses the beta-methylaspartate pathway for acetate formation. Propionate formation occurred through a direct oxidation of glutamate via succinyl-CoA and methylmalonyl-CoA. The metabolism of T. acidaminovorans shifted in favour of propionate formation when grown in coculture with the methanogen, but this did not lead to the use of a different glutamate degradation pathway. Strain TGO, an obligate syntrophic glutamate-degrading organism, formed propionate, traces of succinate, CO(2), NH(4)(+) and H(2). Glutamate was converted to propionate oxidatively via the intermediates succinyl-CoA and methylmalonyl-CoA. A minor part of the succinyl-CoA was converted to succinate and excreted.

  5. 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.

  6. Denitrifying sulfur conversion-associated EBPR: The effect of pH on anaerobic metabolism and performance.

    PubMed

    Guo, Gang; Wu, Di; Hao, Tianwei; Mackey, Hamish Robert; Wei, Li; Chen, Guanghao

    2017-10-15

    The performance of the denitrifying sulfur conversion-associated enhanced biological phosphorus removal (DS-EBPR) process tends to be unstable and requires further study and development. This in turn requires extensive study of the anaerobic metabolism in terms of its stoichiometry and kinetics. This study evaluates the corresponding responses of DS-EBPR to pH, as it significantly influences both stoichiometry and biochemical kinetics. The impacts of five representative pH values ranging between 6.5 and 8.5 on the anaerobic metabolism were investigated, followed by identification of the optimal pH for performance optimization. A mature DS-EBPR sludge was used in the study, enriched with approximately 30% sulfate-reducing bacteria (SRB) and 33% sulfide-oxidizing bacteria (SOB). Through a series of batch tests, the optimal pH range was determined as 7.0-7.5. In this pH range, the anaerobic stoichiometry of phosphorus released/volatile fatty acid (VFA) uptake ratio, sulfate reduction, and internal polymer production (including poly-β-hydroxyalkanoates and polysulfide and/or elemental sulfur) all increased along with the anaerobic kinetics of the VFA uptake ratio. Consequently, phosphorus removal was maximized at this pH range (≥95% vs. 84-93% at other pH values), as was sulfur conversion (16 mg S/L vs. 10-13 mg S/L). This pH range therefore favors the activity and synergy of the key functional bacteria (i.e. SRB and SOB). Anaerobic maintenance tests showed these bacteria required 38-61% less energy for maintenance than that reported for GAOs regardless of pH changes, improving their ability to cope with anaerobic starvation. Adversely, both bacteria showed much lower VFA uptake rates than that of GAOs at all tested pH values (0.03-0.06 vs. 0.2-0.24 mol-C/C-mol biomass/h), possibly revealing the primary cause of frequent instability in the DS-EBPR process. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Monochloramine cometabolism by Nitrosomonas europaea under drinking water conditions.

    PubMed

    Maestre, Juan P; Wahman, David G; Speitel, Gerald E

    2013-09-01

    Chloramine is widely used in United States drinking water systems as a secondary disinfectant, which may promote the growth of nitrifying bacteria because ammonia is present. At the onset of nitrification, both nitrifying bacteria and their products exert a monochloramine demand, decreasing the residual disinfectant concentration in water distribution systems. This work investigated another potentially significant mechanism for residual disinfectant loss: monochloramine cometabolism by ammonia-oxidizing bacteria (AOB). Monochloramine cometabolism was studied with the pure culture AOB Nitrosomonas europaea (ATCC 19718) in batch kinetic experiments under drinking water conditions. Three batch reactors were used in each experiment: a positive control to estimate the ammonia kinetic parameters, a negative control to account for abiotic reactions, and a cometabolism reactor to estimate the cometabolism kinetic constants. Kinetic parameters were estimated in AQUASIM with a simultaneous fit to all experimental data. The cometabolism reactors showed a more rapid monochloramine decay than in the negative controls, demonstrating that cometabolism occurs. Cometabolism kinetics were best described by a pseudo first order model with a reductant term to account for ammonia availability. Monochloramine cometabolism kinetics were similar to those of ammonia metabolism, and monochloramine cometabolism was a significant loss mechanism (30-60% of the observed monochloramine decay). These results suggest that monochloramine cometabolism should occur in practice and may be a significant contribution to monochloramine decay during nitrification episodes in drinking water distribution systems.

  8. 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.

  9. Potential of high-frequency ultrasounds to improve sludge anaerobic conversion and surfactants removal at different food/inoculum ratio.

    PubMed

    Gallipoli, A; Gianico, A; Gagliano, M C; Braguglia, C M

    2014-05-01

    High-frequency ultrasounds have recently gained interest as oxidative technique for sonochemical degradation of organic contaminants in water. In this study an innovative approach applying 200 kHz ultrasounds to improve both sludge anaerobic biodegradability and decontamination is proposed. Digestion tests were performed on batch reactors fed either with untreated or sonicated sludge, at different food/inoculum (F/I) ratio, in the range 0.3-0.9. First order kinetic highlighted a decreasing trend of the hydrolysis rate by increasing F/I, both for untreated and sonicated sludge. Positive effect of ultrasounds on specific biogas production was evident, but the conversion rate for pretreated sludge was strongly affected by F/I, and decreased by increasing F/I. Anionic surfactants anaerobic removal occurred in all tests, but the effect of ultrasounds was significant only at F/I=0.3. By pretreating sludge with high frequency ultrasounds, low F/I was the ideal ratio improving both sludge anaerobic digestion and decontamination.

  10. Deep Conversion of Carbon Monoxide to Hydrogen and Formation of Acetate by the Anaerobic Thermophile Carboxydothermus hydrogenoformans

    PubMed Central

    Henstra, Anne M.; Stams, Alfons J. M.

    2011-01-01

    Carboxydothermus hydrogenoformans is a thermophilic strictly anaerobic bacterium that catalyses the water gas shift reaction, the conversion of carbon monoxide with water to molecular hydrogen and carbon dioxide. The thermodynamically favorable growth temperature, compared to existing industrial catalytic processes, makes this organism an interesting alternative for production of cheap hydrogen gas suitable to fuel CO-sensitive fuel cells in a future hydrogen economy, provided sufficiently low levels of CO are reached. Here we study CO conversion and final CO levels in cultures of C. hydrogenoformans grown in batch cultures that were started with a 100% CO gas phase with and without removal of formed CO2. Final CO levels were 117 ppm without CO2 removal and below 2 ppm with CO2 removal. The Gibbs free energy change calculated with measured end concentrations and the detection of acetate suggest that C. hydrogenoformans shifted from a hydrogenogenic to an acetogenic metabolism. PMID:21754940

  11. Deep Conversion of Carbon Monoxide to Hydrogen and Formation of Acetate by the Anaerobic Thermophile Carboxydothermus hydrogenoformans.

    PubMed

    Henstra, Anne M; Stams, Alfons J M

    2011-01-01

    Carboxydothermus hydrogenoformans is a thermophilic strictly anaerobic bacterium that catalyses the water gas shift reaction, the conversion of carbon monoxide with water to molecular hydrogen and carbon dioxide. The thermodynamically favorable growth temperature, compared to existing industrial catalytic processes, makes this organism an interesting alternative for production of cheap hydrogen gas suitable to fuel CO-sensitive fuel cells in a future hydrogen economy, provided sufficiently low levels of CO are reached. Here we study CO conversion and final CO levels in cultures of C. hydrogenoformans grown in batch cultures that were started with a 100% CO gas phase with and without removal of formed CO(2). Final CO levels were 117 ppm without CO(2) removal and below 2 ppm with CO(2) removal. The Gibbs free energy change calculated with measured end concentrations and the detection of acetate suggest that C. hydrogenoformans shifted from a hydrogenogenic to an acetogenic metabolism.

  12. Anaerobic Conversion of Lactic Acid to Acetic Acid and 1,2-Propanediol by Lactobacillus buchneri

    PubMed Central

    Oude Elferink, Stefanie J. W. H.; Krooneman, Janneke; Gottschal, Jan C.; Spoelstra, Sierk F.; Faber, Folkert; Driehuis, Frank

    2001-01-01

    The degradation of lactic acid under anoxic conditions was studied in several strains of Lactobacillus buchneri and in close relatives such as Lactobacillus parabuchneri, Lactobacillus kefir, and Lactobacillus hilgardii. Of these lactobacilli, L. buchneri and L. parabuchneri were able to degrade lactic acid under anoxic conditions, without requiring an external electron acceptor. Each mole of lactic acid was converted into approximately 0.5 mol of acetic acid, 0.5 mol of 1,2-propanediol, and traces of ethanol. Based on stoichiometry studies and the high levels of NAD-linked 1,2-propanediol-dependent oxidoreductase (530 to 790 nmol min−1 mg of protein−1), a novel pathway for anaerobic lactic acid degradation is proposed. The anaerobic degradation of lactic acid by L. buchneri does not support cell growth and is pH dependent. Acidic conditions are needed to induce the lactic-acid-degrading capacity of the cells and to maintain the lactic-acid-degrading activity. At a pH above 5.8 hardly any lactic acid degradation was observed. The exact function of anaerobic lactic acid degradation by L. buchneri is not certain, but some results indicate that it plays a role in maintaining cell viability. PMID:11133436

  13. Cometabolic degradation of trichloroethylene in a bubble column bioscrubber

    SciTech Connect

    Hecht, V.; Brebbermann, D.; Bremer, P.; Deckwer, W.D.

    1995-08-20

    A bubble column bioreactor was used as bioscrubber to carry out a feasibility study for the cometabolic degradation of trichloroethylene (TCE). Phenol was used as cosubstrate and inducer. The bioreactor was operated like a conventional chemostat with regard to the cosubstrate and low dilution rates were used to minimize the liquid outflow. TCE degradation measurements were carried out using superficial gas velocities between 0.47 and 4.07 cm s{sup {minus}1} and TCE gas phase loads between 0.07 and 0.40 mg L{sup {minus}1}. Depending on the superficial gas velocity used, degrees of conversion between 30% and 80% were obtained. A simplified reactor model using plug flow for the gas phase, mixed flow for the liquid phase, and pseudo first order reaction kinetics for the conversion of TCE was established. The model is able to give a reasonable approximation of the experimental data. TCE degradation at the used experimental conditions is mainly limited by reaction rate rather than by mass transfer rate. The model can be used to calculate the reactor value and the biomass concentration for a required conversion.

  14. 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.

  15. Conversion of municipal solid waste into carboxylic acids by anaerobic countercurrent fermentation: effect of using intermediate lime treatment.

    PubMed

    Aiello-Mazzarri, Cateryna; Coward-Kelly, Guillermo; Agbogbo, Frank K; Holtzapple, Mark T

    2005-11-01

    Municipal solid waste (MSW) and sewage sludge (SS) were combined and anaerobically converted into carboxylate salts by using a mixed culture of acid-forming microorganisms. MSW is an energy source and SS is a source of nutrients. In this study, MSW and SS were combined, so they complemented each other. Four fermentors were arranged in series for a countercurrent fermentation process. In this process, the solids and liquid were transferred in opposite directions, with the addition of fresh biomass to fermentor 1 and fresh liquid media to fermentor 4. An intermediate lime treatment of solids exiting fermentor 3 before entering fermentor 4 was applied to improve the product acid concentration from the untreated MSW/SS fermentations. All fermentations were performed under anaerobic conditions at 40 degrees C. Calcium carbonate was added to neutralize the carboxylic acids and to control the pH. Iodoform was used as a methanogen inhibitor. Carboxylic acid concentration and gas composition were determined by gas chromatography. Substrate conversion was measured by volatile solids loss, and carboxylic acid productivity was calculated as the function of the total carboxylic acids produced, the amount of liquid in all fermentors, and time. The addition of intermediate lime treatment increased product concentration and conversion by approx 30 and 15%, respectively. The highest carboxylic acid concentrations for untreated MSW/SS fermentations with and without intermediate lime treatment were 22.2 and 17.7 g of carboxylic acid/L of liquid, respectively. These results confirm that adding a treatment step between fermentor 3 and fermentor 4 will increase the digestibility and acid productivity of the fermentation.

  16. Pretreatment of pulp mill secondary sludge for high-rate anaerobic conversion to biogas.

    PubMed

    Wood, Nicholas; Tran, Honghi; Master, Emma

    2009-12-01

    Three pretreatment methods were compared based on their ability to increase the extent and rate of anaerobic bioconversion of pulp mill secondary sludge to biogas. The pretreatment technologies used in these experiments were: (i) thermal pretreatment performed at 170 degrees C; (ii) thermochemical (caustic) pretreatment performed at pH 12 and 140 degrees C; and (iii) sonication performed at 20 kHz and 1 W mL(-1). Sludge samples were obtained from a sulfite and a kraft pulp mill, and biochemical methane potential (BMP) assays were performed using microbial granules obtained from a high-rate anaerobic digester operating at a pulp mill. Biogas production from untreated sludge was 0.05 mL mg(-1) of measured chemical oxygen demand (COD) and 0.20 mL mg(-1) COD for kraft and sulfite sludge, respectively. Thermal pretreatment had the highest impact on sludge biodegradability. In this case, biogas yield and production rate from sulfite sludge increased by 50% and 10 times, respectively, while biogas yield and production rate from kraft sludge increased by 280% and 300 times, respectively. Biogas yield correlated to soluble carbohydrate content better than soluble COD.

  17. Value-adding conversion and volume reduction of sewage sludge by anaerobic co-digestion with crude glycerol.

    PubMed

    Kurahashi, Kensuke; Kimura, Chie; Fujimoto, You; Tokumoto, Hayato

    2017-05-01

    In this study, conversion of sewage sludge to biogas by anaerobic co-digestion with crude glycerol was examined. When 0.126g/L crude glycerol was added to the reactor, only methane was produced. Upon addition of 5.04g/L crude glycerol, hydrogen production occurred, and a significant amount of 1,3-propanediol (1,3-PDO) was generated in the liquid phase. On day 6, the dry weight was largely composed of organic acids (48%) and 1,3-PDO (17%), which are water-soluble. Degradation of 1,3-PDO was very slow, which is advantageous for recovery. Crude glycerol, which contains alkaline substances, promoted organic matter degradation by microorganisms, which possibly affected biogas and 1,3-PDO production. Addition of 0.630-2.52g/L glycerol initially led to hydrogen production, followed by methane production a few days later, which stabilized within 1week. In conclusion, adjustment of the crude glycerol concentration allows controllable conversion to value-added products for co-digestion.

  18. Mechanism of anaerobic ether cleavage: conversion of 2-phenoxyethanol to phenol and acetaldehyde by Acetobacterium sp.

    PubMed

    Speranza, Giovanna; Mueller, Britta; Orlandi, Maximilian; Morelli, Carlo F; Manitto, Paolo; Schink, Bernhard

    2002-04-05

    2-Phenoxyethanol is converted into phenol and acetate by a strictly anaerobic Gram-positive bacterium, Acetobacterium strain LuPhet1. Acetate results from oxidation of acetaldehyde that is the early product of the biodegradation process (Frings, J., and Schink, B. (1994) Arch. Microbiol. 162, 199-204). Feeding experiments with resting cell suspensions and 2-phenoxyethanol bearing two deuterium atoms at either carbon of the glycolic moiety as substrate demonstrated that the carbonyl group of the acetate derives from the alcoholic function and the methyl group derives from the adjacent carbon. A concomitant migration of a deuterium atom from C-1 to C-2 was observed. These findings were confirmed by NMR analysis of the acetate obtained by fermentation of 2-phenoxy-[2-(13)C,1-(2)H(2)]ethanol, 2-phenoxy-[1-(13)C,1-(2)H(2)]ethanol, and 2-phenoxy-[1,2-(13)C(2),1-(2)H(2)]ethanol. During the course of the biotransformation process, the molecular integrity of the glycolic unit was completely retained, no loss of the migrating deuterium occurred by exchange with the medium, and the 1,2-deuterium shift was intramolecular. A diol dehydratase-like mechanism could explain the enzymatic cleavage of the ether bond of 2-phenoxyethanol, provided that an intramolecular H/OC(6)H(5) exchange is assumed, giving rise to the hemiacetal precursor of acetaldehyde. However, an alternative mechanism is proposed that is supported by the well recognized propensity of alpha-hydroxyradical and of its conjugate base (ketyl anion) to eliminate a beta-positioned leaving group.

  19. 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.

  20. Monochloramine Cometabolism by Nitrifying Biofilm Relevant to Drinking Water

    EPA Science Inventory

    Recently, biological monochloramine removal (i.e., cometabolism) by a pure culture ammonia–oxidizing bacteria, Nitrosomonas europaea, and a nitrifying mixed–culture have been shown to increase monochloramine demand. Although important, these previous suspended culture batch kine...

  1. Monochloramine Cometabolism by Nitrifying Biofilm Relevant to Drinking Water

    EPA Science Inventory

    Recently, biological monochloramine removal (i.e., cometabolism) by a pure culture ammonia–oxidizing bacteria, Nitrosomonas europaea, and a nitrifying mixed–culture have been shown to increase monochloramine demand. Although important, these previous suspended culture batch kine...

  2. 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.

  3. Modeling of trihalomethane cometabolism in nitrifying biofilters.

    PubMed

    Wahman, David G; Katz, Lynn E; Speitel, Gerald E

    2007-01-01

    The computer program AQUASIM was used to model biofilter experiments seeded with Lake Austin, Texas mixed-culture nitrifiers. These biofilters degraded four trihalomethanes (THMs) (trichloromethane (TCM) or chloroform, bromodichloromethane (BDCM), dibromochloromethane (DBCM), tribromomethane (TBM) or bromoform) commonly found in treated drinking water. Apparent steady-state data from the biofilter experiments and supporting batch experiments were used to estimate kinetic parameters for TCM, DBCM and ammonia degradation. Subsequently, the model was verified against other experimental biofilter data. To allow for full-scale simulations, BDCM and TBM rate constants were estimated using data from batch kinetic studies. Finally, the model was used to simulate full-scale filter performance under different filter surface loading rates and THM speciation seen in practice. Overall, total THM removals ranged from 16% to 54% in these simulations with influent total THM concentrations of 75-82microg/L, which illustrates the potential of THM cometabolism to have a significant impact on treated water quality.

  4. Predicting yields for autotrophic and cometabolic processes

    SciTech Connect

    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 heterotrophic 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.

  5. Cometabolism of 3,4-dichlorobenzoate by Acinetobacter sp. strain 4-CB1.

    PubMed Central

    Adriaens, P; Focht, D D

    1991-01-01

    When Acinetobacter sp. strain 4-CB1 was grown on 4-chlorobenzoate (4-CB), it cometabolized 3,4-dichlorobenzoate (3,4-DCB) to 3-chloro-4-hydroxybenzoate (3-C-4-OHB), which could be used as a growth substrate. No cometabolism of 3,4-DCB was observed when Acinetobacter sp. strain 4-CB1 was grown on benzoate. 4-Carboxyl-1,2-benzoquinone was formed as an intermediate from 3,4-DCB and 3-C-4-OHB in aerobic and anaerobic resting-cell incubations and was the major transient intermediate found when cells were grown on 3-C-4-OHB. The first dechlorination step of 3,4-DCB was catalyzed by the 4-CB dehalogenase, while a soluble dehalogenase was responsible for dechlorination of 3-C-4-OHB. Both enzymes were inducible by the respective chlorinated substrates, as indicated by oxygen uptake experiments. The dehalogenase activity on 3-C-4-OHB, observed in crude cell extracts, was 109 and 44 nmol of 3-C-4-OHB min-1 mg of protein-1 under anaerobic and aerobic conditions, respectively. 3-Chloro-4-hydroxybenzoate served as a pseudosubstrate for the 4-hydroxybenzoate monooxygenase by effecting oxygen and NADH consumption without being hydroxylated. Contrary to 4-CB metabolism, the results suggest that 3-C-4-OHB was not metabolized via the protocatechuate pathway. Despite the ability of resting cells grown on 4-CB or 3-C-4-OHB to carry out all of the necessary steps for dehalogenation and catabolism of 3,4-DCB, it appeared that 3,4-DCB was unable to induce the necessary 4-CB dehalogenase for the initial p-dehalogenation step.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2036004

  6. In situ aerobic cometabolism of chlorinated solvents: a review.

    PubMed

    Frascari, Dario; Zanaroli, Giulio; Danko, Anthony S

    2015-01-01

    The possible approaches for in situ aerobic cometabolism of aquifers and vadose zones contaminated by chlorinated solvents are critically evaluated. Bioaugmentation of resting-cells previously grown in a fermenter and in-well addition of oxygen and growth substrate appear to be the most promising approaches for aquifer bioremediation. Other solutions involving the sparging of air lead to satisfactory pollutant removals, but must be integrated by the extraction and subsequent treatment of vapors to avoid the dispersion of volatile chlorinated solvents in the atmosphere. Cometabolic bioventing is the only possible approach for the aerobic cometabolic bioremediation of the vadose zone. The examined studies indicate that in situ aerobic cometabolism leads to the biodegradation of a wide range of chlorinated solvents within remediation times that vary between 1 and 17 months. Numerous studies include a simulation of the experimental field data. The modeling of the process attained a high reliability, and represents a crucial tool for the elaboration of field data obtained in pilot tests and for the design of the full-scale systems. Further research is needed to attain higher concentrations of chlorinated solvent degrading microbes and more reliable cost estimates. Lastly, a procedure for the design of full-scale in situ aerobic cometabolic bioremediation processes is proposed.

  7. Anaerobic fluid-bed treatment of coal conversion wastewater: Fifth quarterly technical progress report for the period August 15 to November 15, 1987

    SciTech Connect

    Suidan, M.T.; Pfeffer, J.T.; Nakhala, G.F.; Traegner, U.K.

    1987-01-01

    Anaerobic fluidized-bed granular activated carbon (GAC) reactors have been proven successful for the treatment of biologically inhibiting wastewaters such as coal conversion wastewaters. However, in treating such wastewaters which contain compounds that not only resist biodegradation, BUT ALSO INHIBIT THE DEGRADATION OF OTHER COMPOUNDS, adsorption on granular activated carbon represents a viable strategy for the removal of these inhibitory compounds. Since the adsorptive capacity of the reactor media is limited, partial replacement of the carbon bed is then necessary to maintain the concentration of inhibitory compounds below threshold levels. The hydraulic detention time and the associated carbon inventory maintenance represent the single most important capital cost parameter. The objectives of this research are to determine, using experimental and modeling strategies, the effects of hydraulic detention time and the schedule of GAC replacement on the performance of these fluidized bed GAC anaerobic reactors. This objective is realized by the following activities: operation of two expanded-bed GAC anaerobic reactors at empty-bed hydraulic detention times of 1.0 and 0.5 days. These reactors will be referred to as reactors 1 and 2, respectively. The wastewater fed to the two reactors includes phenol, acetic acid and o-cresol as model compounds of a real coal conversion wastewater. Development of a mathematical model of the expanded-bed GAC anaerobic reactor incorporating the various interactions that occur in this process such as biodegradation, adsorption on GAC, and the regular replacement of reactor GAC with virgin media. 1 ref., 1 fig., 6 tabs.

  8. Coupled Biogeochemical Process Evaluation for Conceptualizing Trichloroethylene Co-Metabolism

    SciTech Connect

    Rick Colwell; Corey Radtke; Mark Delwiche; Deborah Newby; Lynn Petzke; Mark Conrad; Eoin Brodie; Hope Lee; Bob Starr; Dana Dettmers; Ron Crawford; Andrzej Paszczynski; Nick Bernardini; Ravi Paidisetti; Tonia Green

    2006-06-01

    Chlorinated solvent wastes (e.g., trichloroethene or TCE) often occur as diffuse subsurface plumes in complex geological environments where coupled processes must be understood in order to implement remediation strategies. Monitored natural attenuation (MNA) warrants study as a remediation technology because it minimizes worker and environment exposure to the wastes and because it costs less than other technologies. However, to be accepted MNA requires different ?lines of evidence? indicating that the wastes are effectively destroyed. We are studying the coupled biogeochemical processes that dictate the rate of TCE co-metabolism first in the medial zone (TCE concentration: 1,000 to 20,000 ?g/L) of a plume at the Idaho National Laboratory?s Test Area North (TAN) site and then at Paducah or the Savannah River Site. We will use flow-through in situ reactors (FTISR) to investigate the rate of methanotrophic co-metabolism of TCE and the coupling of the responsible biological processes with the dissolved methane flux and groundwater flow velocity. TCE co-metabolic rates at TAN are being assessed and interpreted in the context of enzyme activity, gene expression, and cellular inactivation related to intermediates of TCE co-metabolism. By determining the rate of TCE co-metabolism at different groundwater flow velocities, we will derive key modeling parameters for the computational simulations that describe the attenuation, and thereby refine such models while assessing the contribution of microbial co-metabolism relative to other natural attenuation processes. This research will strengthen our ability to forecast the viability of MNA at DOE and other sites contaminated with chlorinated hydrocarbons.

  9. 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

  10. Anaerobic fluid-bed treatment of coal conversion wastewater: Second quarterly technical progress report for the period November 16, 1986-February 15, 1987

    SciTech Connect

    Suidan, M.T.; Pfeffer, J.T.; Nakhla, G.F.; Traegner, U.K.

    1987-01-01

    The objectives of the research project are to determine, using simultaneous experimental and modeling strategies, the effects of the hydraulic detention time and the schedule of granular activated carbon (GAC) replacement on the performance of the expanded-bed GAC anaerobic reactor during the treatment of biologically inhibiting coal conversion wastewaters. The hydraulic detention time and the associated carbon inventory represents the single most important capital cost parameter while GAC replacement, which is needed to maintain the concentrations of toxic compounds below threshold levels, represents a major operating cost parameter.

  11. 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...

  12. 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...

  13. 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...

  14. 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...

  15. Anaerobic fluid-bed treatment of coal conversion wastewater: Third quarterly technical progress report for the period February 16-May 15, 1987

    SciTech Connect

    Suidan, M.T.; Pfeffer, J.T.; Nakhala, G.F.; Traegner, U.K.

    1987-06-01

    Anaerobic fluidized-bed GAC reactors have been proven successful for the treatment of biologically inhibiting wastewaters such as coal conversion wastewaters. However, in treating such wastewaters, which contain compounds that not only resist biodegradation but also inhibit the degradation of other compounds, adsorption on granular activated carbon (GAC) is a viable strategy for the removal of these inhibitory compounds. Since the adsorptive capacity of the reactor media is limited, partial replacement of the carbon bed is then necessary to maintain the concentration of inhibitory compounds below threshold levels. The cost of the GAC replacement thus represents a major operating cost of the system. The hydraulic detention time and the associated carbon inventory represents the single most important capital cost parameter. The objectives of this research are to determine, using experimental and modeling strategies, the effects of hydraulic detention time and the schedule of GAC replacement on the performance of fluidized bed GAC anaerobic reactors during the treatment of coal conversion wastewater. This objective is realized by the described activities.

  16. Anaerobic fluid-bed treatment of coal conversion wastewater: Eighth quarterly technical progress report for the period May 15, 1988--August 15, 1988

    SciTech Connect

    Suidan, M.T.; Pfeffer, J.T.; Nakhla, G.F.; Traegner, U.K.

    1988-01-01

    Anaerobic fluidized-bed GAC reactors have been proven successful for the treatment of biologically inhibiting wastewaters such as coal conversion wastewaters. However, in treating such wastewaters which contain compounds that not only resist biodegradation but also inhibit the degradation of other compounds, adsorption on granular activated carbon (GAC) represents a viable strategy for the removal of these inhibitory compounds. Since the adsorptive capacity of the reactor media is limited, partial replacement of the carbon bed is then necessary to maintain the concentration of inhibitory compounds below threshold levels. The cost of the GAC replacement thus represents a major operating cost of the system. The hydraulic detention time and the associated carbon inventory represent the single most important capital cost parameter. The objectives of this research are to determine, using experimental and modeling strategies, the effects of hydraulic detention time and the schedule of GAC replacement on the performance of fluidized-bed GAC anaerobic reactors during the treatment of coal conversion wastewater. 1 ref., 3 figs., 1 tab.

  17. Anaerobic fluid-bed treatment of coal conversion wastewater: Sixth quarterly technical progress report for the period November 15, 1987 to February 15, 1988

    SciTech Connect

    Suidan, M.T.; Pfeffer, J.T.; Nakhla, G.F.; Traegner, U.K.

    1988-01-01

    Anaerobic fluidized-bed GAC reactors have been proven successful for the treatment of biolgoically inhibiting watewaters such as coal conversion wastewaters. However, in treating such wastewaters which contain compounds that not only resist biodegradation but also inhibit the degradation of other compounds, adsorption on granular activated carbon (GAC) represent a viable strategy for the removal of these inhibitory compounds. Since the adsorptive capacity of the reactor media is limited, partial replacement of the carbon bed is then necessary to maintain the concentration of inhibitory compounds below threshold levels. The cost of the GAC replacement thus represents a major operating cost of the system. The hydraulic detention time and the assoicated carbon inventory represent the single most important capital cost parameter. The objectives of this research are to determine, using experimental and modeling strategies, the effects of hydraulic detention time and the schedule of GAC replacement on the performance of fluidized bed GAC anaerobic reactors during the treatment of coal conversion wastewater. 1 ref., 1 tab.

  18. Anaerobic fluid-bed treatment of coal conversion wastewater: Fourth quarterly technical progress report for the period May 15 to August 15, 1987

    SciTech Connect

    Suidan, M.T.; Pfeffer, J.T.; Nakhala, G.F.; Traegner, U.K.

    1987-01-01

    Anaerobic fluidized-bed GAC reactors have been proven successful for the treatment of biologically inhibiting wastewaters such as coal conversion wastewaters. However, in treating such wastewaters which contain compounds that not only resist biodegradation but also inhibit the degradation of other compounds, adsorption on granular activated carbon (GAC) is a viable strategy for the removal of these inhibitory compounds. Since the adsorptive capacity of the reactor media is limited, partial replacement of the carbon bed is then necessary to maintain the concentration of inhibitory compounds below threshold levels. The cost of the GAC replacement thus represents a major operating cost of the system. The hydraulic detention time and the associated carbon inventory represent the single most important capital cost parameter. The objectives of this research are to determine, using experimental and modeling strategies, the effects of hydraulic detention time and the schedule of GAC replacement on the performance of fluidized bed GAC anaerobic reactors during the treatment of coal conversion wastewater. 7 figs., 2 tabs.

  19. Coupled Biogeochemical Process Evaluation for Conceptualizing Trichloroethylene Co-Metabolism

    SciTech Connect

    Colwell, Frederick; Radtke, Corey; Newby, Deborah; Delwiche, Mark; Crawf, Ronald L.; Paszczynski, Andrzej; Strap, Janice; Conrad, Mark; Brodic, Eoin; Starr, Robert; Lee, Hope

    2006-04-05

    Chlorinated solvent wastes (e.g., trichloroethene or TCE) often occur as diffuse subsurface plumes in complex geological environments where coupled processes must be understood in order to implement remediation strategies. Monitored natural attenuation (MNA) warrants study as a remediation technology because it minimizes worker and environment exposure to the wastes and because it costs less than other technologies. However, to be accepted MNA requires 'lines of evidence' indicating that the wastes are effectively destroyed. Our research will study the coupled biogeochemical processes that dictate the rate of TCE co-metabolism in contaminated aquifers first at the Idaho National Laboratory and then at Paducah or the Savannah River Site, where natural attenuation of TCE is occurring. We will use flow-through in situ reactors to investigate the rate of methanotrophic co-metabolism of TCE and the coupling of the responsible biological processes with the dissolved methane flux and groundwater flow velocity. We will use new approaches (e.g., stable isotope probing, enzyme activity probes, real-time reverse transcriptase polymerase chain reaction, proteomics) to assay the TCE co-metabolic rates, and interpret these rates in the context of enzyme activity, gene expression, and cellular inactivation related to intermediates of TCE co-metabolism. By determining the rate of TCE co-metabolism at different methane concentrations and groundwater flow velocities, we will derive key modeling parameters for the computational simulations that describe the attenuation, and thereby refine such models while assessing the contribution of microbial relative to other natural attenuation processes. This research will strengthen our ability to forecast the viability of MNA at DOE and other sites that are contaminated with chlorinated hydrocarbons.

  20. Effect of carbon monoxide, hydrogen and sulfate on thermophilic (55 degrees C) hydrogenogenic carbon monoxide conversion in two anaerobic bioreactor sludges.

    PubMed

    Sipma, J; Meulepas, R J W; Parshina, S N; Stams, A J M; Lettinga, G; Lens, P N L

    2004-04-01

    The conversion routes of carbon monoxide (CO) at 55 degrees C by full-scale grown anaerobic sludges treating paper mill and distillery wastewater were elucidated. Inhibition experiments with 2-bromoethanesulfonate (BES) and vancomycin showed that CO conversion was performed by a hydrogenogenic population and that its products, i.e. hydrogen and CO2, were subsequently used by methanogens, homo-acetogens or sulfate reducers depending on the sludge source and inhibitors supplied. Direct methanogenic CO conversion occurred only at low CO concentrations [partial pressure of CO (PCO) <0.5 bar (1 bar=10(5) Pa)] with the paper mill sludge. The presence of hydrogen decreased the CO conversion rates, but did not prevent the depletion of CO to undetectable levels (<400 ppm). Both sludges showed interesting potential for hydrogen production from CO, especially since after 30 min exposure to 95 degrees C, the production of CH4 at 55 degrees C was negligible. The paper mill sludge was capable of sulfate reduction with hydrogen, tolerating and using high CO concentrations (PCO>1.6 bar), indicating that CO-rich synthesis gas can be used efficiently as an electron donor for biological sulfate reduction.

  1. High-throughput pyrosequencing analysis of bacteria relevant to cometabolic and metabolic degradation of ibuprofen in horizontal subsurface flow constructed wetlands.

    PubMed

    Li, Yifei; Wu, Bing; Zhu, Guibing; Liu, Yu; Ng, Wun Jern; Appan, Adhityan; Tan, Soon Keat

    2016-08-15

    The potential toxicity of pharmaceutical residues including ibuprofen on the aquatic vertebrates and invertebrates has attracted growing attention to the pharmaceutical pollution control using constructed wetlands, but there lacks of an insight into the relevant microbial degradation mechanisms. This study investigated the bacteria associated with the cometabolic and metabolic degradation of ibuprofen in a horizontal subsurface flow constructed wetland system by high-throughput pyrosequencing analysis. The ibuprofen degradation dynamics, bacterial diversity and evenness, and bacterial community structure in a planted bed with Typha angustifolia and an unplanted bed (control) were compared. The results showed that the plants promoted the microbial degradation of ibuprofen, especially at the downstream zones of wetland. However, at the upstream one-third zone of wetland, the presence of plants did not significantly enhance ibuprofen degradation, probably due to the much greater contribution of cometabolic behaviors of certain non-ibuprofen-degrading microorganisms than that of the plants. By analyzing bacterial characteristics, we found that: (1) The aerobic species of family Flavobacteriaceae, family Methylococcaceae and genus Methylocystis, and the anaerobic species of family Spirochaetaceae and genus Clostridium_sensu_stricto were the most possible bacteria relevant to the cometabolic degradation of ibuprofen; (2) The family Rhodocyclaceae and the genus Ignavibacterium closely related to the plants appeared to be associated with the metabolic degradation of ibuprofen.

  2. Conversion of phenols during anaerobic digestion of organic solid waste--a review of important microorganisms and impact of temperature.

    PubMed

    Levén, Lotta; Nyberg, Karin; Schnürer, Anna

    2012-03-01

    During anaerobic digestion of organic waste, both energy-rich biogas and a nutrient-rich digestate are produced. The digestate can be used as a fertiliser in agricultural soils if the levels of hazardous compounds and pathogens are low. This article reviews the main findings about phenols in anaerobic digestion processes degrading organic solid wastes, and examines the effect of process temperature on the anaerobic degradation of phenols, the microbial community and the quality of the digestate. The degradation efficiency of a number of different phenols has been shown to be correlated to the process temperature. Higher degradation efficiency is observed at mesophilic process temperature than at thermophilic temperature. Possible explanations for this variation in the degradation of phenols include differences in diversity, particularly of the phenol-degrading bacteria, and/or the presence of temperature-sensitive enzymes. Chemical analysis of digestate from bioreactors operating at thermophilic temperature detected a higher content of phenols compared to mesophilic bioreactors, verifying the degradation results. Digestate with the highest phenol content has the greatest negative impact on soil microbial activity.

  3. 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 ...

  4. 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.

  5. Monochloramine Cometabolism by Mixed-Culture Nitrifiers under Drinking Water Conditions.

    PubMed

    Maestre, Juan P; Wahman, David G; Speitel, Gerald E

    2016-06-21

    Chloramines are the second most used secondary disinfectant by United States water utilities. However, chloramination may promote nitrifying bacteria. Recently, monochloramine cometabolism by the pure culture ammonia-oxidizing bacteria, Nitrosomonas europaea, was shown to increase monochloramine demand. The current research investigated monochloramine cometabolism by nitrifying mixed cultures grown under more relevant drinking water conditions and harvested from sand-packed reactors before conducting suspended growth batch kinetic experiments. Four types of batch kinetic experiments were conducted: (1) positive controls to estimate ammonia kinetic parameters, (2) negative controls to account for biomass reactivity, (3) utilization associated product (UAP) controls to account for UAP reactivity, and (4) cometabolism experiments to estimate cometabolism kinetic parameters. Kinetic parameters were estimated in AQUASIM with a simultaneous fit to the experimental data. Cometabolism kinetics were best described by a first-order model. Monochloramine cometabolism kinetics were similar to those of ammonia metabolism, and monochloramine cometabolism accounted for 30% of the observed monochloramine loss. These results demonstrated that monochloramine cometabolism occurred in mixed cultures similar to those found in drinking water distribution systems; therefore, monochloramine cometabolism may be a significant contribution to monochloramine loss during nitrification episodes in drinking water distribution systems.

  6. Efficacy of pentane, toluene, and benzene to support aerobic cometabolism of ethylene dibromide.

    PubMed

    Danko, Anthony S; Leitão, Patrícia O; Verce, Matthew F; Freedman, David L

    2012-11-15

    The ability of pentane, benzene, and toluene to support aerobic cometabolism of ethylene dibromide (1,2-dibromoethane, EDB) was evaluated. A pentane enrichment culture cometabolized EDB, with a transformation capacity of 0.35 μmol EDB/mg biomass (66.2 μg EDB/mg biomass) in the absence of growth substrate. It also cometabolized EDB while actively growing on pentane. However, enrichment cultures grown on benzene or toluene could not cometabolize EDB, with or without their respective growth substrates. Copyright © 2012 Elsevier B.V. All rights reserved.

  7. Cometabolic degradation of chlorinated solvents: Bacterial inhibition, inactivation, and recovery

    SciTech Connect

    Ely, R.L.; Williamson, K.J.; Hyman, M.R.; Arp, D.J.

    1995-12-31

    This paper summarizes an approach for quantifying degradation kinetics and bacterial activity changes during cometabolic degradation of chlorinated solvents, results from trichloroethylene (TCE) degradation experiments, and a mathematical model addressing fluctuations in activity caused by enzyme inhibition, inactivation, and respondent enzyme synthesis. Using Nitrosomonas duropaea as a slow-growing exemplar capable of effecting cometabolic transformations, quasi-steady-state ammonia oxidation was established in a small bioreactor. A chlorinated solvent was injected to perturb the system, and bacterial activity and solvent degradation were monitored. At TCE concentrations to about 3.5 mg/L, from slight to nearly complete ammonia monooxygenase (AMO) inactivation occurred without causing immediate cell death. Results suggested cellular injury was limited primarily to AMO, most metabolic systems remained functional, and bacterial recovery processes, independent of cell growth, were initiated while degrading TCE.

  8. High pressure homogenization and two-phased anaerobic digestion for enhanced biogas conversion from municipal waste sludge.

    PubMed

    Wahidunnabi, Abdullahil K; Eskicioglu, Cigdem

    2014-12-01

    This study compared advanced anaerobic digestion combining two-phased anaerobic digestion (2PAD) with high pressure homogenization (HPH) pretreatment to conventional anaerobic digestion of municipal sludge at laboratory scale. The study began with examination of thickened waste activated sludge (TWAS) solubilization due to HPH pretreatment at different pressure (0-12,000 psi) and chemical dose (0.009-0.036 g NaOH/g total solids). Homogenizing pressure was found as the most significant factor (p-value < 0.05) for increasing solubilization of particulate chemical oxygen demand (COD) and biopolymers in TWAS. Based on the preliminary results, a pretreatment with chemical dose of 0.009 g NaOH/g total solids and pressure of 12,000 psi was selected for digester studies. Upon acclimation of anaerobic inocula to pretreatments, a total number of twelve lab-scale digesters were operated under scenarios including single-stage (control), 2PAD, and HPH coupled with 2PAD (HPH + 2PAD) at sludge retention times (SRTs) of 20, 14 and 7 days. Between mesophilic and thermophilic temperatures, mesophilic digestion was found to benefit more from pretreatments. Relative (to control) improvements in methane yield and volatile solids (VS) removals increased noticeably as SRT was shortened from 20 to 14 and 7 days. HPH + 2PAD system was found to achieve the maximum methane production (0.61-1.32 L CH4/Ldigester-d) and VS removals (43-64%). Thermophilic control, 2PAD and HPH + 2PAD systems resulted in significant pathogen removals meeting Class A biosolids requirements according to Organic Matter Recycling Regulations (OMRR) of British Columbia (BC) at 20 d SRT. Energy analysis indicated that all the digestion scenarios attained positive energy balance with 2PAD system operated at 20 d SRT producing the maximum net energy of 4.76 GJ/tonne CODadded.

  9. Evaluating alternate biokinetic models for trace pollutant cometabolism.

    PubMed

    Liu, Li; Binning, Philip J; Smets, Barth F

    2015-02-17

    Mathematical models of cometabolic biodegradation kinetics can improve our understanding of the relevant microbial reactions and allow us to design in situ or in-reactor applications of cometabolic bioremediation. A variety of models are available, but their ability to describe experimental data has not been systematically evaluated for a variety of operational/experimental conditions. Here five different models were considered: first-order; Michaelis-Menten; reductant; competition; and combined models. The models were assessed on their ability to fit data from simulated batch experiments covering a realistic range of experimental conditions. The simulated observations were generated by using the most complex model structure and parameters based on the literature, with added experimental error. Three criteria were used to evaluate model fit: ability to fit the simulated experimental data, identifiability of parameters using a colinearity analysis, and suitability of the model size and complexity using the Bayesian and Akaike Information criteria. Results show that no single model fits data well for a range of experimental conditions. The reductant model achieved best results, but required very different parameter sets to simulate each experiment. Parameter nonuniqueness was likely to be due to the parameter correlation. These results suggest that the cometabolic models must be further developed if they are to reliably simulate experimental and operational data.

  10. Enhancement of waste activated sludge protein conversion and volatile fatty acids accumulation during waste activated sludge anaerobic fermentation by carbohydrate substrate addition: the effect of pH.

    PubMed

    Feng, Leiyu; Chen, Yinguang; Zheng, Xiong

    2009-06-15

    Volatile fatty acids (VFAs), the carbon source of biological nutrients removal, can be produced by waste activated sludge (WAS) anaerobic fermentation. However, because of high protein content and low carbon to nitrogen mass ratio (C/N) of WAS, the production of VFAs, especially propionic acid, a more preferred VFA than acetic acid for enhanced biological phosphorus removal (EBPR), is limited. After the addition of carbohydrate (rice was used as the model matter) to the WAS anaerobic fermentation system to balance the C/N ratio, the effect of pH on WAS protein conversion and VFAs production was investigated in this paper. Experimental results showed that the addition of carbohydrate matter caused a remarkable enhancement of WAS protein conversion and protease activity, and an apparent synergistic effect between WAS and carbohydrate matter was observed. The study of pH effect revealed that pH influenced not only the total VFAs production but the percentage of individual VFA. The maximal VFAs production (520.1 mg COD per gram of volatile suspended solids (VSS)) occurred at pH 8.0 and a fermentation time of 8 d, which was more than three times that at uncontrolled pH (150.2 mg COD/g VSS). The analysis of the composition of VFAs showed that propionic acid ranked first at pH 6.0-9.0 (around 50%) whereas acetic acid was the dominant product at other pHs investigated. Thus, the suitable conditions for propionic acid-enriched VFAs production were pH 8.0 and a time of 8 d. Further investigation showed that as there was more fermentation substrate consumption with lower biogas generation at pH 8.0, improved VFAs production was observed. Also, the key enzymes relevant to propionic acid formation exhibited the highest activities at pH 8.0, which resulted in the greatest propionic acid content in the fermentative VFAs. The 16S rRNA gene clone library demonstrated that Clostridia, beta-Proteobacteria, and Bacteroidetes were the dominant microbial community when the current

  11. STRATEGIES FOR THE AEROBIC CO-METABOLISM OF CHLORINATED SOLVENTS. (R825689C019)

    EPA Science Inventory

    Abstract

    Recent field and laboratory studies have evaluated the potential for aerobic co-metabolism of chlorinated solvents. Different co-metabolic substrates and different methods of application have been tried, including growing indigenous microbes in situ, an...

  12. Replica plating method for estimating phenanthrene-utilizing and phenanthrene-cometabolizing microorganisms

    SciTech Connect

    Shiaris, M.P.; Cooney, J.J.

    1983-02-01

    A replica plating method was developed for detecting and enumerating phenanthrene-degrading microorganisms. The method is designed to discriminate between aquatic organisms that utilize phenanthrene as the sole carbon and energy source and organisms that cometabolize phenanthrene. The method was used to demonstrate that phenanthrene utilizers and phenanthrene cometabolizers coexist in estuarine sediments.

  13. Energy conversion of biomass crops and agroindustrial residues by combined biohydrogen/biomethane system and anaerobic digestion.

    PubMed

    Corneli, Elisa; Dragoni, Federico; Adessi, Alessandra; De Philippis, Roberto; Bonari, Enrico; Ragaglini, Giorgio

    2016-07-01

    Aim of this study was to evaluate the suitability of ensiled giant reed, ensiled maize, ensiled olive pomace, wheat bran for combined systems (CS: dark fermentation+anaerobic digestion (AD)) producing hydrogen-rich biogas (biohythane), tested in batch under basic operational conditions (mesophilic temperatures, no pH control). Substrates were also analyzed under a single stage AD batch test, in order to investigate the effects of DF on estimated energy recovery (ER) in combined systems. In CS, maize and wheat bran exhibited the highest hydrogen potential (13.8 and 18.9NLkgVS(-1)) and wheat bran the highest methane potential (243.5NLkgVS(-1)). In one-stage AD, giant reed, maize and wheat bran showed the highest methane production (239.5, 267.3 and 260.0NLkgVS(-1)). Butyrate/acetate ratio properly described the dark fermentation, correlating with hydrogen production (r=0.92). Wheat bran proved to be a promising residue for CS in terms of hydrogen/methane potential and ER.

  14. Kinetics of aerobic cometabolic biodegradation of chlorinated and brominated aliphatic hydrocarbons: A review.

    PubMed

    Jesus, João; Frascari, Dario; Pozdniakova, Tatiana; Danko, Anthony S

    2016-05-15

    This review analyses kinetic studies of aerobic cometabolism (AC) of halogenated aliphatic hydrocarbons (HAHs) from 2001-2015 in order to (i) compare the different kinetic models proposed, (ii) analyse the estimated model parameters with a focus on novel HAHs and the identification of general trends, and (iii) identify further research needs. The results of this analysis show that aerobic cometabolism can degrade a wide range of HAHs, including HAHs that were not previously tested such as chlorinated propanes, highly chlorinated ethanes and brominated methanes and ethanes. The degree of chlorine mineralization was very high for the chlorinated HAHs. Bromine mineralization was not determined for studies with brominated aliphatics. The examined research period led to the identification of novel growth substrates of potentially high interest. Decreasing performance of aerobic cometabolism were found with increasing chlorination, indicating the high potential of aerobic cometabolism in the presence of medium- and low-halogenated HAHs. Further research is needed for the AC of brominated aliphatic hydrocarbons, the potential for biofilm aerobic cometabolism processes, HAH-HAH mutual inhibition and the identification of the enzymes responsible for each aerobic cometabolism process. Lastly, some indications for a possible standardization of future kinetic studies of HAH aerobic cometabolism are provided.

  15. Aerobic Microbial Cometabolism of Benzothiophene and 3-Methylbenzothiophene

    PubMed Central

    Fedorak, Phillip M.; Grbić-Galić, Dunja

    1991-01-01

    A culture enriched by growth on 1-methylnaphthalene was used to study the aerobic biotransformations of benzothiophene and 3-methylbenzothiophene. Neither of the sulfur heterocyclic compounds would support growth, but they were transformed by the culture growing on 1-methylnaphthalene or glucose or peptone. Cometabolism of benzothiophene yielded benzothiophene-2,3-dione, whereas that of 3-methylbenzothiophene yielded 3-methylbenzothiophene sulfoxide and the corresponding sulfone. The identities of the dione and sulfone were verified by comparison with authentic standards. The identity of the sulfoxide was surmised from gas chromatography-mass spectrometry and gas chromatography- Fourier transform infrared spectroscopy results. Oxidation preferentially occurred at carbons 2 and 3 in benzothiophene, but when carbon 3 was substituted with a methyl group, as in 3-methylbenzothiophene, the sulfur atom was oxygenated. The predominant microorganism in the enrichment culture was a Pseudomonas strain, designated BT1, which mineralized aromatic but not aliphatic hydrocarbons. This isolate cometabolized benzothiophene and 3-methylbenzothiophene. There was no evidence that it could metabolize 3-methylbenzothiophene sulfone. When 3-methylbenzothiophene was added to Prudhoe Bay crude oil, the sulfur heterocycle was oxidized to its sulfoxide and sulfone by strain BT1 as it grew on the aromatic hydrocarbons in the crude oil. Benzothiophene-2,3-dione was found to be chemically unstable when incubated with Prudhoe Bay crude oil. Thus its formation from benzothiophene in the presence of crude oil could not be determined. PMID:16348471

  16. 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 ...

  17. 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 ...

  18. A study on cometabolic bioventing for the in situ remediation of trichloroethylene.

    PubMed

    Sui, Hong; Li, Xingang; Huang, Guoqiang; Jiang, Bin

    2006-01-01

    Cometabolic bioventing for removal of TCE in the unsaturated zone was studied in a soil column study using methane as growth substrate. A numerical model was developed for simulating the behavior of TCE during cometabolic bioventing. The model parameters were estimated independently through laboratory batch experiments or from the literature. Simulations were found to provide reasonable agreement with the experimental data. The experimental data show that a total TCE remediation efficiency of over 95% was obtained. The volatilization-to-biodegradation ratio of TCE was about 7:1 and T ( c ) values ranging from 0.0078 to 0.07 were obtained in this methane-driven system. Due to the toxicity of the high TCE concentrations to the microbial biomass in the initial stages of the experiment, cometabolic biodegradation was enhanced and was more efficient in the later stages of cometabolic bioventing.

  19. Trichloroethylene aerobic cometabolism by suspended and immobilized butane-growing microbial consortia: a kinetic study.

    PubMed

    Frascari, Dario; Zanaroli, Giulio; Bucchi, Giacomo; Rosato, Antonella; Tavanaie, Nasrin; Fraraccio, Serena; Pinelli, Davide; Fava, Fabio

    2013-09-01

    A kinetic study of butane uptake and trichloroethylene (TCE) aerobic cometabolism was conducted by two suspended-cell (15 and 30°C) and two attached-cell (15 and 30°C) consortia obtained from the indigenous biomass of a TCE-contaminated aquifer. The shift from suspended to attached cells resulted in an increase of butane (15 and 30°C) and TCE (15°C) biodegradation rates, and a significant decrease of butane inhibition on TCE biodegradation. The TCE 15°C maximum specific biodegradation rate was equal to 0.011 mg(TCE ) mg(protein)(-1) d(-1) with suspended cells and 0.021 mg(TCE) mg(protein)(-1) d(-1) with attached cells. The type of mutual butane/TCE inhibition depended on temperature and biomass conditions. On the basis of a continuous-flow simulation, a packed-bed PFR inoculated with the 15 or 30°C attached-cell consortium could attain a 99.96% conversion of the studied site's average TCE concentration with a 0.4-0.5-day hydraulic residence time, with a low effect of temperature on the TCE degradation performances.

  20. Factors limiting aliphatic chlorocarbon degradation by Nitrosomonas europaea: Cometabolic inactivation of ammonia monooxygenase and substrate specificity

    SciTech Connect

    Rasche, M.E.; Hyman, M.R.; Arp, D.J. )

    1991-10-01

    The soil nitrifying bacterium Nitrosomonas europaea is capable of degrading trichloroethylene (TCE) and other halogenated hydrocarbons. TCE cometabolism by N. europaea resulted in an irreversible loss of TCE biodegradative capacity, ammonia-oxidizing activity, and ammonia-dependent O{sub 2} uptake by the cells. Inactivation was not observed in the presence of allylthiourea, a specific inhibitor of enzyme ammonia monooxygenase, or under anaerobic conditions, indicating that the TCE-mediated inactivation required ammonia monooxygenase activity. When N. europaea cells were incubated with ({sup 14}C)TCE under conditions which allowed turnover of ammonia monooxygenase, a number of cellular proteins were covalently labeled with {sup 14}C. Treatment of cells with allylthiourea or acetylene prior to incubation with ({sup 14}C)TCE prevented incorporation of {sup 14}C into proteins. The ammonia-oxidizing activity of cells inactivated in the presence of TCE could be recovered through a process requiring de novo protein synthesis. In addition to TCE, a series of chlorinated methanes, ethanes, and other ethylenes were screened as substrates for ammonia monooxygenase and for their ability to inactivate the ammonia-oxidizing system of N. europaea. The chlorocarbons would be divided into three classes depending on their biodegradability and inactivating potential: (1) compounds which were not biodegradable by N. europaea and which had no toxic effect on the cells (2) compounds which were cooxidized by N. europaea and had little or no toxic effect on the cells; and (3) compounds which were cooxidized and produced a turnover-dependent inactivation of ammonia oxidation by N. europaea.

  1. Cometabolic degradation of organic wastewater micropollutants by activated sludge and sludge-inherent microorganisms.

    PubMed

    Fischer, Klaus; Majewsky, Marius

    2014-08-01

    Municipal wastewaters contain a multitude of organic trace pollutants. Often, their biodegradability by activated sludge microorganisms is decisive for their elimination during wastewater treatment. Since the amounts of micropollutants seem too low to serve as growth substrate, cometabolism is supposed to be the dominating biodegradation process. Nevertheless, as many biodegradation studies were performed without the intention to discriminate between metabolic and cometabolic processes, the specific contribution of the latter to substance transformations is often not clarified. This minireview summarizes current knowledge about the cometabolic degradation of organic trace pollutants by activated sludge and sludge-inherent microorganisms. Due to their relevance for communal wastewater contamination, the focus is laid on pharmaceuticals, personal care products, antibiotics, estrogens, and nonylphenols. Wherever possible, reference is made to the molecular process level, i.e., cometabolic pathways, involved enzymes, and formed transformation products. Particular cometabolic capabilities of different activated sludge consortia and various microbial species are highlighted. Process conditions favoring cometabolic activities are emphasized. Finally, knowledge gaps are identified, and research perspectives are outlined.

  2. Carbon conversion efficiency and population dynamics of a marine algae-bacteria consortium growing on simplified synthetic digestate: first step in a bioprocess coupling algal production and anaerobic digestion.

    PubMed

    Vasseur, Christophe; Bougaran, Gaël; Garnier, Matthieu; Hamelin, Jérôme; Leboulanger, Christophe; Le Chevanton, Myriam; Mostajir, Behzad; Sialve, Bruno; Steyer, Jean-Philippe; Fouilland, Eric

    2012-09-01

    Association of microalgae culture and anaerobic digestion seems a promising technology for sustainable algal biomass and biogas production. The use of digestates for sustaining the growth of microalgae reduces the costs and the environmental impacts associated with the substantial algal nutrient requirements. A natural marine algae-bacteria consortium was selected by growing on a medium containing macro nutrients (ammonia, phosphate and acetate) specific of a digestate, and was submitted to a factorial experimental design with different levels of temperature, light and pH. The microalgal consortium reached a maximum C conversion efficiency (i.e. ratio between carbon content produced and carbon supplied through light photosynthetic C conversion and acetate) of 3.6%. The presence of bacteria increased this maximum C conversion efficiency up to 6.3%. The associated bacterial community was considered beneficial to the total biomass production by recycling the carbon lost during photosynthesis and assimilating organic by-products from anaerobic digestion. Copyright © 2012 Elsevier Ltd. All rights reserved.

  3. Anaerobic bacteria

    MedlinePlus

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

  4. Manipulating pyruvate to acetyl-CoA conversion in Escherichia coli for anaerobic succinate biosynthesis from glucose with the yield close to the stoichiometric maximum.

    PubMed

    Skorokhodova, Alexandra Yu; Morzhakova, Anastasiya A; Gulevich, Andrey Yu; Debabov, Vladimir G

    2015-11-20

    Efficient succinate production in Escherichia coli is attained during anaerobic glucose fermentation in biosynthetic processes combining the reductive branch of the TCA cycle and the glyoxylate bypass. Pyruvate dehydrogenase (PDH) or pyruvate formate lyase (PFL) serves in E. coli as a source of acetyl-CoA, a substrate for the glyoxylate bypass. Depending on enzymes responsible for acetyl-CoA generation, the contribution of the glyoxylate bypass to the anaerobic succinate biosynthesis may vary to support redox balance resulting in diverse maximum achievable yield values. Anaerobic succinate biosynthesis from glucose was studied using E. coli strains with altered expression of genes encoding PFL and PDH. For acetyl-CoA formation by PFL, the yield of 1.32 mol succinate per mole of glucose was achieved with the theoretical value of 1.6 mol/mol. Involvement of PDH in anaerobic acetyl-CoA synthesis increased succinate yield up to 1.49 mol/mol, which is 89.8% of the predicted maximum (1.6(6) mol/mol). The maximum yield of 1.69 mol succinate per mol glucose, amounting to 98.8% of the stoichiometric maximum (1.71 mol/mol), was achieved with the strain possessing PDH as the primary anaerobic source of acetyl-CoA. During high cell density fermentation, the best engineered strain produced high amounts of succinate (570.7 mM) and only small quantities of acetate (11.9 mM).

  5. Cometabolic biotransformation of fenpropathrin by Clostridium species strain ZP3.

    PubMed

    Zhang, Songbai; Yin, Lebin; Liu, Yong; Zhang, Deyong; Luo, Xiangwen; Cheng, Ju'e; Cheng, Feixue; Dai, Jianping

    2011-09-01

    A novel bacterial strain capable of degrading the pyrethroid pesticide fenpropathrin was isolated from mixed wastewater and sludge samples. Phylogenetic analysis of the 16S rDNA sequence revealed that the organism belongs to the genus Clostridium. The organism can co-metabolically transform fenpropathrin at 100 mg l(-1) at 35°C and pH 7.5 in 12 days. Metabolic products of fenpropathrin from strain ZP3 were examined by gas chromatography/mass spectrometry, and the results showed that the organism degraded fenpropathrin with an oxidization process to yield benzyl alcohol, benzenemethanol, 3,5-dimethylamphetamine. Analyses of cell-free extracts from this strain showed that the optimal degrading conditions for degrading fenpropathrin were 35°C and pH 7.5, and degradation efficiency was 20.0 mg l(-1) day(-1), and it might be potential using for rapid treating fenpropathrin, for example, on the surface of fruits and vegetables.

  6. 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.

  7. 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.

  8. Anaerobic Infections

    MedlinePlus

    ... doses of antibiotics taken by mouth for months. Bacteroides and Prevotella infections. Bacterial organisms from species called Bacteroides and Prevotella are anaerobic. They are common organisms ...

  9. Biodegradation of Methyl tert-Butyl Ether by Co-Metabolism with a Pseudomonas sp. Strain

    PubMed Central

    Li, Shanshan; Wang, Shan; Yan, Wei

    2016-01-01

    Co-metabolic bioremediation is supposed to be an impressive and promising approach in the elimination technology of methyl tert-butyl ether (MTBE), which was found to be a common pollutant worldwide in the ground or underground water in recent years. In this paper, bacterial strain DZ13 (which can co-metabolically degrade MTBE) was isolated and named as Pseudomonas sp. DZ13 based on the result of 16S rRNA gene sequencing analysis. Strain DZ13 could grow on n-alkanes (C5-C8), accompanied with the co-metabolic degradation of MTBE. Diverse n-alkanes with different carbon number showed a significant influence on the degradation rate of MTBE and accumulation of tert-butyl alcohol (TBA). When Pseudomonas sp. DZ13 co-metabolically degraded MTBE with n-pentane as the growth substrate, a higher MTBE-degrading rate (Vmax = 38.1 nmol/min/mgprotein, Ks = 6.8 mmol/L) and lower TBA-accumulation was observed. In the continuous degradation experiment, the removal efficiency of MTBE by Pseudomonas sp. Strain DZ13 did not show an obvious decrease after five times of continuous addition. PMID:27608032

  10. Cometabolic bioreactor demonstration at the Oak Ridge K-25 Site: Final report

    SciTech Connect

    Lucero, A.J.; Donaldson, T.L.; Jennings, H.L.; Morris, M.I.; Palumbo, A.V.; Herbes, S.E.

    1995-08-01

    The Oak Ridge National Laboratory (ORNL) conducted a demonstration of cometabolic technology for bioremediation of groundwater contaminated with trichloroethylene (TCE) and other chlorinated solvents. The technology demonstration was located at a seep from the K-1070-C/D Classified Burial Ground at the Oak Ridge K-25 Site. The technology demonstration was designed to evaluate the performance of two different types of cometabolic processes. In both cases, the TCE is cometabolized in the sense that utilization of a different primary substrate is necessary to obtain the simultaneous cometabolism of TCE. Trichloroethylene alone is unable to support growth and maintenance of the microorganisms. Methanotrophic (methane-utilizing) technology was demonstrated first; aromatic-utilizing microorganisms were demonstrated later. The demonstration was based on scaleup of laboratory and bench-scale prototype equipment that was used to establish the technical feasibility of the processes.This report documents the operation of the methanotrophic bioreactor system to treat the seep water at the demonstration site. The initial objectives were to demonstrate stable operation of the bioreactors and associated equipment, including the pretreatment and effluent polishing steps; and evaluate the biodegradation of TCE and other organics in the seep water for the three operating modes--air oxidation pretreatment, steam-stripping pretreatment, and no pretreatment.

  11. Cometabolic Degradation of Dibenzofuran and Dibenzothiophene by a Naphthalene-Degrading Comamonas sp. JB.

    PubMed

    Ji, Xiangyu; Xu, Jing; Ning, Shuxiang; Li, Nan; Tan, Liang; Shi, Shengnan

    2017-08-18

    Comamonas sp. JB was used to investigate the cometabolic degradation of dibenzofuran (DBF) and dibenzothiophene (DBT) with naphthalene as the primary substrate. Dehydrogenase and ATPase activity of the growing system with the presence of DBF and DBT were decreased when compared to only naphthalene in the growing system, indicating that the presence of DBF and DBT inhibited the metabolic activity of strain JB. The pathways and enzymes involved in the cometabolic degradation were tested. Examination of metabolites elucidated that strain JB cometabolically degraded DBF to 1,2-dihydroxydibenzofuran, subsequently to 2-hydroxy-4-(3'-oxo-3'H-benzofuran-2'-yliden)but-2-enoic acid, and finally to catechol. Meanwhile, strain JB cometabolically degraded DBT to 1,2-dihydroxydibenzothiophene and subsequently to the ring cleavage product. A series of naphthalene-degrading enzymes including naphthalene dioxygenase, 1,2-dihydroxynaphthalene dioxygenase, salicylaldehyde dehydrogenase, salicylate hydroxylase, and catechol 2,3-oxygenase have been detected, confirming that naphthalene was the real inducer of expression the degradation enzymes and metabolic pathways were controlled by naphthalene-degrading enzymes.

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

    PubMed

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

    2014-05-22

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

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

    PubMed Central

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

    2014-01-01

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

  14. 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.

  15. NADH-regulated metabolic model for growth of Methylosinus trichosporium OB3b. Cometabolic degradation of trichloroethene and optimization of bioreactor system performance

    SciTech Connect

    Sipkema, E.M.; Koning, W. de; Ganzeveld, K.J.; Janssen, D.B.; Beenackers, A.A.C.M.

    2000-04-01

    A metabolic model describing growth of Methylosinus trichosporium OB3b and cometabolic contaminant conversion is used to optimize trichloroethene (TCE) conversion in a bioreactor system. Different process configurations are compared: a growing culture and a nongrowing culture to which TCE is added at both constant and pulsed levels. The growth part of the model, presented in the preceding article, gives a detailed description of the NADH regeneration required for continued TCE conversion. It is based on the metabolic pathways, includes Michaelis--Menten type enzyme kinetics, and uses NADH as an integrating and controlling factor. Here the model is extended to include TCE transformation, incorporating the kinetics of contaminant conversion, the related NADH consumption, toxic effects, and competitive inhibition between TCE and methane. The model realistically describes the experimentally observed negative effects of the TCE conversion products, both on soluble methane monooxygenase through the explicit incorporation of the activity of this enzyme and on cell viability through the distinction between dividing and nondividing cells. In growth-based systems, the toxicity of the TCE conversion products causes rapid cell death, which leads to wash-out of suspended cultures at low TCE loads. Enzyme activity, which is less sensitive, is hardly affected by the toxicity of the TCE conversion products and ensures high conversions (>95%) up to the point of wash-out. Pulsed addition of TCE leads to a complete loss of viability. However, the remaining enzyme activity can still almost completely covert the subsequently added large TCE pulses. This emphasizes the inefficient use of enzyme activity in growth-based systems. A comparison of growth-based and similar non-growth-based systems reveals that the highest TCE conversions per amount of cells grown can be obtained in the latter. Using small amounts of methane, NADH limitation in the second step of this two-step system can be

  16. Development of Effective Aerobic Cometabolic Systems for the In Situ Transformation of Problematic Chlorinated Solvent Mixtures

    DTIC Science & Technology

    2005-02-01

    microorganism, Burkholderia cepacia ENV435 was reported by Steffan et al (1999). In that work, groundwater contaminated with 1000-2500 µg/L...aerobic cometabolism of TCE could be accomplished through bioaugmentation of a genetically modified strain of Burkholderia cepacia G4 (McCarty et al...Enhancement of Trichlorethylene Degradation in Aquifer Microcosms Bioagumented with Wild Type and Genetically Altered Burkholderia (Pseudomonas) cepacia G4

  17. Biogenic Hydrogen Conversion of De-Oiled Jatropha Waste via Anaerobic Sequencing Batch Reactor Operation: Process Performance, Microbial Insights, and CO2 Reduction Efficiency

    PubMed Central

    Lin, Chiu-Yue

    2014-01-01

    We report the semicontinuous, direct (anaerobic sequencing batch reactor operation) hydrogen fermentation of de-oiled jatropha waste (DJW). The effect of hydraulic retention time (HRT) was studied and results show that the stable and peak hydrogen production rate of 1.48 L/L∗d and hydrogen yield of 8.7 mL H2/g volatile solid added were attained when the reactor was operated at HRT 2 days (d) with a DJW concentration of 200 g/L, temperature 55°C, and pH 6.5. Reduced HRT enhanced the production performance until 1.75 d. Further reduction has lowered the process efficiency in terms of biogas production and hydrogen gas content. The effluent from hydrogen fermentor was utilized for methane fermentation in batch reactors using pig slurry and cow dung as seed sources. The results revealed that pig slurry was a feasible seed source for methane generation. Peak methane production rate of 0.43 L CH4/L∗d and methane yield of 20.5 mL CH4/g COD were observed at substrate concentration of 10 g COD/L, temperature 30°C, and pH 7.0. PCR-DGGE analysis revealed that combination of celluloytic and fermentative bacteria were present in the hydrogen producing ASBR. PMID:24672398

  18. Biogenic hydrogen conversion of de-oiled jatropha waste via anaerobic sequencing batch reactor operation: process performance, microbial insights, and CO2 reduction efficiency.

    PubMed

    Kumar, Gopalakrishnan; Lin, Chiu-Yue

    2014-01-01

    We report the semicontinuous, direct (anaerobic sequencing batch reactor operation) hydrogen fermentation of de-oiled jatropha waste (DJW). The effect of hydraulic retention time (HRT) was studied and results show that the stable and peak hydrogen production rate of 1.48 L/L ∗ d and hydrogen yield of 8.7 mL H2/g volatile solid added were attained when the reactor was operated at HRT 2 days (d) with a DJW concentration of 200 g/L, temperature 55 °C, and pH 6.5. Reduced HRT enhanced the production performance until 1.75 d. Further reduction has lowered the process efficiency in terms of biogas production and hydrogen gas content. The effluent from hydrogen fermentor was utilized for methane fermentation in batch reactors using pig slurry and cow dung as seed sources. The results revealed that pig slurry was a feasible seed source for methane generation. Peak methane production rate of 0.43 L CH4/L ∗ d and methane yield of 20.5 mL CH4/g COD were observed at substrate concentration of 10 g COD/L, temperature 30 °C, and pH 7.0. PCR-DGGE analysis revealed that combination of cellulolytic and fermentative bacteria were present in the hydrogen producing ASBR.

  19. Inhibition, Inactivation, and Recovery of Ammonia-Oxidizing Activity in Cometabolism of Trichloroethylene by Nitrosomonas europaea

    PubMed Central

    Hyman, M. R.; Russell, S. A.; Ely, R. L.; Williamson, K. J.; Arp, D. J.

    1995-01-01

    The kinetics of the cometabolism of trichloroethylene (TCE) by the ammonia-oxidizing soil bacterium Nitrosomonas europaea in short-term (<10-min) incubations were investigated. Three individual effects of TCE cometabolism on this bacterium were characterized. First, we observed that TCE is a potent competitive inhibitor of ammonia oxidation by N. europaea. The K(infi) value for TCE (30 (mu)M) is similar to the K(infm) for ammonia (40 (mu)M). Second, we examined the toxicity associated with TCE cometabolism by N. europaea. Stationary-phase cells of N. europaea oxidized approximately 60 nmol of TCE per mg of protein before ammonia-oxidizing activity was completely inactivated by reactive intermediates generated during TCE oxidation. At the TCE concentrations used in these experiments, ammonia did not provide significant protection against inactivation. Third, we have determined the ability of cells to recover ammonia-oxidizing activity after exposure to TCE. Cells recovering from TCE inactivation were compared with cells recovering from the specific inactivation of ammonia-oxidizing activity by light. The recovery kinetics were indistinguishable when 40% or less of the activity was inactivated. However, at increased levels of inactivation, TCE-inactivated cells did not recover as rapidly as light-inactivated cells. The kinetics of recovery appear to be dependent on both the extent of inactivation of ammonia-oxidizing activity and the degree of specificity of the inactivating treatment. PMID:16534997

  20. Field Evidence for Co-Metabolism of Trichloroethene Stimulated by Addition of Electron Donor to Groundwater

    SciTech Connect

    Conrad, Mark E.; Brodie, Eoin L.; Radtke, Corey W.; Bill, Markus; Delwiche, Mark E.; Lee, M. Hope; Swift, Dana L.; Colwell, Frederick S.

    2010-05-17

    For more than 10 years, electron donor has been injected into the Snake River aquifer beneath the Test Area North site of the Idaho National Laboratory for the purpose of stimulating microbial reductive dechlorination of trichloroethene (TCE) in groundwater. This has resulted in significant TCE removal from the source area of the contaminant plume and elevated dissolved CH4 in the groundwater extending 250 m from the injection well. The delta13C of the CH4 increases from 56o/oo in the source area to -13 o/oo with distance from the injection well, whereas the delta13C of dissolved inorganic carbon decreases from 8 o/oo to -13 o/oo, indicating a shift from methanogenesis to methane oxidation. This change in microbial activity along the plume axis is confirmed by PhyloChip microarray analyses of 16S rRNA genes obtained from groundwater microbial communities, which indicate decreasing abundances of reductive dechlorinating microorganisms (e.g., Dehalococcoides ethenogenes) and increasing CH4-oxidizing microorganisms capable of aerobic co-metabolism of TCE (e.g., Methylosinus trichosporium). Incubation experiments with 13C-labeled TCE introduced into microcosms containing basalt and groundwater from the aquifer confirm that TCE co-metabolism is possible. The results of these studies indicate that electron donor amendment designed to stimulate reductive dechlorination of TCE may also stimulate co-metabolism of TCE.

  1. Biological removal of the xenobiotic trichloroethylene (TCE) through cometabolism in nitrifying systems.

    PubMed

    Kocamemi, B Alpaslan; Ceçen, F

    2010-01-01

    In the present study, cometabolic TCE degradation was evaluated using NH(4)-N as the growth-substrate. At initial TCE concentrations up to 845 microg/L, TCE degradation followed first-order kinetics. The increase in ammonium utilization rate favored the degradation of TCE. This ensured that biological transformation of TCE in nitrifying systems is accomplished through a cometabolic pathway by the catalysis of non-specific ammonia oxygenase enzyme of nitrifiers. The transformation yield (T(y)) of TCE, the amount of TCE degraded per unit mass of NH(4)-N, strongly depended on the initial NH(4)-N and TCE concentrations. In order to allow a rough estimation of TCE removal and nitrification at different influent TCE and NH(4)-N concentrations, a linear relationship was developed between 1/T(y) and the initial NH(4)-N/TCE ratio. The estimated T(y) values lead to the conclusion that nitrifying systems are promising candidates for biological removal of TCE through cometabolism.

  2. A model and reactor for the cometabolic biodegradation of chlorinated organics

    SciTech Connect

    Chang, H.L.; Alvarez-Cohen, L.

    1995-12-31

    The oxidization of chlorinated organics by oxygenase expressing organisms is described by a newly developed kinetic model. The kinetics of the cometabolic oxidation of chlorinated organics have been shown to be affected by product toxicity and/or the depletion of reducing energy. In addition, competition between growth substrate and cometabolic substrate for oxygenase enzymes may significantly influence cometabolic degradation rates. In this study, a modification of Michaelis-Menten/Monod kinetics is proposed that incorporates the effects of product toxicity, reducing energy limitation and competitive inhibition, together with cell growth and decay. This model is able to predict the kinetics of chlorinated organic degradation by resting cells of methane, propane, toluene and phenol oxidizing cultures as well as by methane oxidizers under a range of substrate conditions (resting cells, cells with reducing energy substrate, cells with growth substrate). The proposed model is then used together with experimental data to assess the feasibility of bioreactor systems for the treatment of chlorinated organic waste streams.

  3. Biodegradation of pharmaceuticals by Rhodococcus rhodochrous and Aspergillus niger by co-metabolism.

    PubMed

    Gauthier, Hervé; Yargeau, Viviane; Cooper, David G

    2010-03-01

    This work investigated the possible fate of pharmaceuticals in the environment that are known to be resistant to biodegradation. A co-metabolism approach, adding a readily degradable carbon source, was used to study the biodegradation of some pharmaceuticals. The pharmaceuticals selected were all known to be micro pollutants and frequently used by humans. The microorganisms used primarily were Rhodococcus rhodochrous, known to co-metabolize difficult to degrade hydrocarbons and Aspergillus niger. Because of the long periods of time required for the degradation experiments after growth had reached the stationary phase, it was found to be necessary to correct for water loss from the media. Co-metabolism of carbamazepine, sulfamethizole and sulfamethoxazole was observed and as much as 20% of these compounds could be removed. Small amounts of stable metabolites were observed during the degradation of some of these drugs and these were different from the metabolites obtained from abiotic degradation. A metabolite arising from the biodegradation of sulfamethoxazole by R.rhodochrous was identified.

  4. A cometabolic biotransformation model for halogenated aliphatic compounds exhibiting product toxicity

    SciTech Connect

    Alvarez-Cohen, L. ); McCarty, P.L. )

    1991-08-01

    A model is proposed to describe the rate and extent of cometabolic transformation of halogenated aliphatic compounds by resting microbial cells. The finite transformation capacity ({Tc}) of resting cells, which appears to be associated with cometabolic oxidation of many halogenated aliphatic compounds, is used to incorporate the effects of product toxicity and reductant supply into a modified expression of Monod kinetics. Applicability of the model of trichloroethylene transformation by resting cells from a mixed methanotrophic culture is evaluated by comparison with experimental data from batch transformation studies conducted over a range of conditions. A visually good and statistically reasonable fit was obtained between the experimental data and model predictions both with cells alone and with formate added as an exogenous reductant source. A comparison of parameter estimates (k and K{sub s}) derived by use of the cometabolic transformation model and those derived by use of conventional linearized Monod techniques (Lineweaver-Burk and concentration-normalized equations) indicates that, for reactions involving a finite transformation capacity, the linearized Monod equations yield artificially elevated parameters estimates.

  5. Microbial community adaptation influences long-chain fatty acid conversion during anaerobic codigestion of fats, oils, and grease with municipal sludge.

    PubMed

    Ziels, Ryan M; Karlsson, Anna; Beck, David A C; Ejlertsson, Jörgen; Yekta, Sepehr Shakeri; Bjorn, Annika; Stensel, H David; Svensson, Bo H

    2016-10-15

    Codigesting fats, oils, and greases with municipal wastewater sludge can greatly improve biomethane recovery at wastewater treatment facilities. Process loading rates of fats, oils, and greases have been previously tested with little knowledge of the digester microbial community structure, and high transient fat loadings have led to long chain fatty acid (LCFA) accumulation and digester upsets. This study utilized recently-developed quantitative PCR assays for syntrophic LCFA-degrading bacteria along with 16S amplicon sequencing to relate changes in microbial community structure to LCFA accumulation during transient loading increases to an anaerobic codigester receiving waste restaurant oil and municipal wastewater sludge. The 16S rRNA gene concentration of the syntrophic β-oxidizing genus Syntrophomonas increased to ∼15% of the Bacteria community in the codigester, but stayed below 3% in the control digester that was fed only wastewater sludge. Methanosaeta and Methanospirillum were the dominant methanogenic genera enriched in the codigester, and together comprised over 80% of the Archaea community by the end of the experimental period. Constrained ordination showed that changes in the codigester Bacteria and Archaea community structures were related to measures of digester performance. Notably, the effluent LCFA concentration in the codigester was positively correlated to the specific loading rate of waste oil normalized to the Syntrophomonas 16S rRNA concentration. Specific loading rates of 0-1.5 × 10(-12) g VS oil/16S gene copies-day resulted in LCFA concentrations below 30 mg/g TS, whereas LCFA accumulated up to 104 mg/g TS at higher transient loading rates. Based on the community-dependent loading limitations found, enhanced biomethane production from high loadings of fats, oils and greases can be achieved by promoting a higher biomass of slow-growing syntrophic consortia, such as with longer digester solids retention times. This work also

  6. Pilot-scale conversion of lime-treated wheat straw into bioethanol: quality assessment of bioethanol and valorization of side streams by anaerobic digestion and combustion

    PubMed Central

    Maas, Ronald HW; Bakker, Robert R; Boersma, Arjen R; Bisschops, Iemke; Pels, Jan R; de Jong, Ed; Weusthuis, Ruud A; Reith, Hans

    2008-01-01

    Introduction The limited availability of fossil fuel sources, worldwide rising energy demands and anticipated climate changes attributed to an increase of greenhouse gasses are important driving forces for finding alternative energy sources. One approach to meeting the increasing energy demands and reduction of greenhouse gas emissions is by large-scale substitution of petrochemically derived transport fuels by the use of carbon dioxide-neutral biofuels, such as ethanol derived from lignocellulosic material. Results This paper describes an integrated pilot-scale process where lime-treated wheat straw with a high dry-matter content (around 35% by weight) is converted to ethanol via simultaneous saccharification and fermentation by commercial hydrolytic enzymes and bakers' yeast (Saccharomyces cerevisiae). After 53 hours of incubation, an ethanol concentration of 21.4 g/liter was detected, corresponding to a 48% glucan-to-ethanol conversion of the theoretical maximum. The xylan fraction remained mostly in the soluble oligomeric form (52%) in the fermentation broth, probably due to the inability of this yeast to convert pentoses. A preliminary assessment of the distilled ethanol quality showed that it meets transportation ethanol fuel specifications. The distillation residue, which contained non-hydrolysable and non-fermentable (in)organic compounds, was divided into a liquid and solid fraction. The liquid fraction served as substrate for the production of biogas (methane), whereas the solid fraction functioned as fuel for thermal conversion (combustion), yielding thermal energy, which can be used for heat and power generation. Conclusion Based on the achieved experimental values, 16.7 kg of pretreated wheat straw could be converted to 1.7 kg of ethanol, 1.1 kg of methane, 4.1 kg of carbon dioxide, around 3.4 kg of compost and 6.6 kg of lignin-rich residue. The higher heating value of the lignin-rich residue was 13.4 MJ thermal energy per kilogram (dry basis). PMID

  7. Pilot-scale conversion of lime-treated wheat straw into bioethanol: quality assessment of bioethanol and valorization of side streams by anaerobic digestion and combustion.

    PubMed

    Maas, Ronald Hw; Bakker, Robert R; Boersma, Arjen R; Bisschops, Iemke; Pels, Jan R; de Jong, Ed; Weusthuis, Ruud A; Reith, Hans

    2008-08-12

    The limited availability of fossil fuel sources, worldwide rising energy demands and anticipated climate changes attributed to an increase of greenhouse gasses are important driving forces for finding alternative energy sources. One approach to meeting the increasing energy demands and reduction of greenhouse gas emissions is by large-scale substitution of petrochemically derived transport fuels by the use of carbon dioxide-neutral biofuels, such as ethanol derived from lignocellulosic material. This paper describes an integrated pilot-scale process where lime-treated wheat straw with a high dry-matter content (around 35% by weight) is converted to ethanol via simultaneous saccharification and fermentation by commercial hydrolytic enzymes and bakers' yeast (Saccharomyces cerevisiae). After 53 hours of incubation, an ethanol concentration of 21.4 g/liter was detected, corresponding to a 48% glucan-to-ethanol conversion of the theoretical maximum. The xylan fraction remained mostly in the soluble oligomeric form (52%) in the fermentation broth, probably due to the inability of this yeast to convert pentoses. A preliminary assessment of the distilled ethanol quality showed that it meets transportation ethanol fuel specifications. The distillation residue, which contained non-hydrolysable and non-fermentable (in)organic compounds, was divided into a liquid and solid fraction. The liquid fraction served as substrate for the production of biogas (methane), whereas the solid fraction functioned as fuel for thermal conversion (combustion), yielding thermal energy, which can be used for heat and power generation. Based on the achieved experimental values, 16.7 kg of pretreated wheat straw could be converted to 1.7 kg of ethanol, 1.1 kg of methane, 4.1 kg of carbon dioxide, around 3.4 kg of compost and 6.6 kg of lignin-rich residue. The higher heating value of the lignin-rich residue was 13.4 MJ thermal energy per kilogram (dry basis).

  8. Cometabolic Enzymatic Transformation of Organic Micropollutants under Methanogenic Conditions.

    PubMed

    Gonzalez-Gil, Lorena; Carballa, Marta; Lema, Juan M

    2017-02-23

    Anaerobic digestion (AD) has been shown to have the biological potential to decrease concentrations of several organic micropollutants (OMPs) in sewage sludge. However, the mechanisms and factors behind these biotransformations, which are essential for elucidating the possible transformation products and to foster the complete removal of OMPs via operational strategies, remain unclear. Therefore, this study investigated the transformation mechanisms of 20 OMPs during the methanogenic step of AD with a focus on the role of acetate kinase (AK), which is a key enzyme in methane production. The results from lab-scale methanogenic reactors showed that this step accounts for much of the reported OMP biotransformation in AD. Furthermore, enzymatic assays confirmed that AK transforms galaxolide, naproxen, nonylphenol, octylphenol, ibuprofen, diclofenac, bisphenol A, and triclosan. Except for galaxolide, for which further studies are required to refine conclusions, the OMP's chemical structure was a determinant for AK action because only compounds that contain a carboxyl or hydroxyl group and have moderate steric hindrance were enzymatically transformed, likely by phosphorylation. For these seven compounds, this enzymatic mechanism accounts for 10-90% of the measured methanogenic biotransformation, suggesting that other active enzymes of the AD process are also involved in OMP biotransformation.

  9. Biocatalysis conversion of methanol to methane in an upflow anaerobic sludge blanket (UASB) reactor: Long-term performance and inherent deficiencies.

    PubMed

    Lu, Xueqin; Zhen, Guangyin; Chen, Mo; Kubota, Kengo; Li, Yu-You

    2015-12-01

    Long-term performance of methanol biocatalysis conversion in a lab-scale UASB reactor was evaluated. Properties of granules were traced to examine the impact of methanol on granulation. Methanolic wastewater could be stably treated during initial 240d with the highest biogas production rate of 18.6 ± 5.7 L/Ld at OLR 48 g-COD/Ld. However, the reactor subsequently showed severe granule disintegration, inducing granule washout and process upsets. Some steps (e.g. increasing influent Ca(2+) concentration, etc.) were taken to prevent rising dispersion, but no clear improvement was observed. Further characterizations in granules revealed that several biotic/abiotic factors all caused the dispersion: (1) depletion of extracellular polymeric substances (EPS) and imbalance of protein/polysaccharide ratio in EPS; (2) restricted formation of hard core and weak Ca-EPS bridge effect due to insufficient calcium supply; and (3) simplification of species with the methanol acclimation. More efforts are required to solve the technical deficiencies observed in methanolic wastewater treatment.

  10. 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

  11. Metabolism and Cometabolism of Cyclic Ethers by a Filamentous Fungus, a Graphium sp.▿

    PubMed Central

    Skinner, Kristin; Cuiffetti, Lynda; Hyman, Michael

    2009-01-01

    The filamentous fungus Graphium sp. (ATCC 58400) grows on gaseous n-alkanes and diethyl ether. n-Alkane-grown mycelia of this strain also cometabolically oxidize the gasoline oxygenate methyl tert-butyl ether (MTBE). In this study, we characterized the ability of this fungus to metabolize and cometabolize a range of cyclic ethers, including tetrahydrofuran (THF) and 1,4-dioxane (14D). This strain grew on THF and other cyclic ethers, including tetrahydropyran and hexamethylene oxide. However, more vigorous growth was consistently observed on the lactones and terminal diols potentially derived from these ethers. Unlike the case in all previous studies of microbial THF oxidation, a metabolite, γ-butyrolactone, was observed during growth of this fungus on THF. Growth on THF was inhibited by the same n-alkenes and n-alkynes that inhibit growth of this fungus on n-alkanes, while growth on γ-butyrolactone or succinate was unaffected by these inhibitors. Propane and THF also behaved as mutually competitive substrates, and propane-grown mycelia immediately oxidized THF, without a lag phase. Mycelia grown on propane or THF exhibited comparable high levels of hemiacetal-oxidizing activity that generated methyl formate from mixtures of formaldehyde and methanol. Collectively, these observations suggest that THF and n-alkanes may initially be oxidized by the same monooxygenase and that further transformation of THF-derived metabolites involves the activity of one or more alcohol dehydrogenases. Both propane- and THF-grown mycelia also slowly cometabolically oxidized 14D, although unlike THF oxidation, this reaction was not sustainable. Specific rates of THF, 14D, and MTBE degradation were very similar in THF- and propane-grown mycelia. PMID:19581469

  12. Co-metabolic biodegradation of DBP by Paenibacillus sp. S-3 and H-2.

    PubMed

    Jin, Lei; Sun, Xiumei; Zhang, Xiaojun; Guo, Yuanming; Shi, Hui

    2014-06-01

    Two di-n-butyl phthalate (DBP)-degrading strains, designated as S-3 and H-2, were isolated from DBP-polluted soil and both identified as Paenibacillus sp. When DBP was provided as the sole carbon source, about 45.5 and 71.7 % of DBP (100 mg/L) were degraded by strain S-3 and H-2, respectively, after incubation for 48 h. However, DBP (100 mg/L) was degraded completely by co-culture of strain S-3 and H-2 after incubation for 60 h. Four phthalic acid (PA) esters could be utilized by co-metabolism in the study and the degradation rates followed the order of dimethyl phthalate > diethyl phthalate > DBP > dioctyl phthalate. The metabolic pathway of DBP was elucidated based on the results of metabolites identification and enzyme assays. For strain S-3, DBP was degraded into butyl hydrogen phthalate which was degraded to PA by carboxyesterase further. But PA could be not hydrolyzed further because strain S-3 lacked 3,4-phthalate dioxygenase. Different with S-3, strain H-2 could hydrolyze PA into 3,4-dihydroxy-PA by 3,4-phthalate dioxygenase. Then 3,4-dihydroxy-PA was converted to protocatechuate and benzoic acid. Finally, the aromatic ring was cleavage and mineralized to CO2 and H2O. Above all, co-metabolism could increase the activity of 3,4-phthalate dioxygenase and accelerated the degradation of DBP. This study highlights an important potential use of co-metabolic biodegradation for the in situ bioremediation of DBP and its metabolites-contaminated environment.

  13. Anaerobic degradation of 2,4,6-trinitrotoluene in granular activated carbon fluidized bed and batch reactors.

    PubMed

    Moteleb, M A; Suidan, M T; Kim, J; Davel, J L; Adrian, N R

    2001-01-01

    In this study, an anaerobic fluidized bed reactor (AFBR) was used to treat a synthetically produced pink water waste stream containing trinitrotoluene (TNT). The synthesized waste consisted of 95 mg/l-TNT, the main contaminant in pink water, which was to be co-metabolized with 560-mg/l ethanol. Granular activated carbon was used as the attachment medium for biological growth. TNT was reduced to a variety of compounds, mainly 2,4,6-triaminotoluene (2,4,6-TAT), 2,4-diamino-6-nitrotoluene (2,4-DA-6-NT), 2,6-diamino-4-nitrotoluene (2,6-DA-4-NT), 2-amino-4,6-dinitrotoluene (2-A-4,6-DNT), and 4-amino-2,6-dinitrotoluene (4-A-2,6-DNT). These conversions resulted through the oxidation of ethanol to carbon dioxide under anoxic conditions, or reduction to methane under methanogenic conditions. The anaerobic reactor was charged with 1.0 kg of 16 x 20 U.S. Mesh Granular Activated Carbon (GAC) and was pre-loaded with 200 g of TNT prior to the addition of the mixed seed culture. During the first three weeks of operation, ethanol was completely degraded and no methane was produced. Effluent inorganic carbon revealed stoichiometric conversion of the feed ethanol to dissolved inorganic carbon with accumulation of carbon dioxide in the headspace of the reactor. GAC extraction showed incremental reduction of the nitro groups to amino groups, with 2,4,6-TAT as the final product. After three weeks, the oxygen from the nitro groups was depleted and methane production commenced. The reproducibility of this phenomenon was confirmed by repeating the experiment in the same manner using an identical AFBR. Furthermore, serum bottle tests were conducted using TNT loading ratios of 0.2, 0.4, 0.8, 1.0 g-TNT/g-GAC as well as experiments in the absence of GAC. Similar behavior to that of the columns was observed, with degradation rates varying according to the particular condition. GAC greatly enhanced the degradation rates and the higher TNT loading resulted in slower degradation rates of ethanol.

  14. Effects of Phenol Feeding Pattern on Microbial Community Structure and Cometabolism of Trichloroethylene

    PubMed Central

    Shih, C.; Davey, M. E.; Zhou, J.; Tiedje, J. M.; Criddle, C. S.

    1996-01-01

    Cometabolism of trichloroethylene (TCE) by phenol-fed enrichments was evaluated in four reactors with distinct phenol feeding patterns. The reactors were inoculated from the same source, operated at the same average dilution rate, and received the same mass of phenol over time. Only the timing of phenol addition differed. Reactor C received phenol continuously; reactor SC5 received phenol semicontinuously--alternating between 5 h of feed and 3 h without feed; reactor SC2 alternated between 2 h of feed and 6 h without feed; and reactor P received a single pulse every 24 h. The structure of the enrichments and their capacity for TCE transformation were analyzed. In long-term operation, reactors C and SC5 were dominated by fungi, had higher levels of predators, were more susceptible to biomass fluctuations, and exhibited reduced capacity for TCE transformation. Reactors P and SC2 were characterized by lower levels of fungi, higher bacterial biomass, higher concentrations of TCE-degrading organisms, and higher rates of TCE transformation. After 200 days of operation, rates of TCE transformation increased 10-fold in reactor P, resulting in TCE transformation rates that were 20 to 100 times higher than the rates of the other reactor communities. The cause of this shift is unknown. Isolates capable of the highest rates of TCE transformation were obtained from reactor P. We conclude that cometabolic activity depends upon microbial community structure and that the community structure can be manipulated by altering the growth substrate feeding pattern. PMID:16535382

  15. A cometabolic kinetics model incorporating enzyme inhibition, inactivation, and recovery. 2: Trichloroethylene degradation experiments

    SciTech Connect

    Ely, R.L.; Hyman, M.R.; Arp, D.J.; Guenther, R.B.; Williamson, K.J.

    1995-05-05

    A cometabolism enzyme kinetics model has been presented which takes into account changes in bacterial activity associated with enzyme inhibition, inactivation of enzyme resulting from product toxicity, and respondent synthesis of new enzyme. Although this process is inherently unsteady-state, the model assumes that cometabolic degradation of a compound exhibiting product toxicity can be modeled as pseudo-steady-state under certain conditions. In its simplified form, the model also assumes that enzyme inactivation is directly proportional to nongrowth substrate oxidation, and that recovery is directly proportional to growth substrate oxidation. In part 1, model derivation, simplification, and analyses were described. In this article, model assumptions are tested by analyzing data from experiments examining trichloroethylene (TCE) degradation by the ammonia-oxidizing bacterium Nitrosomonas europaea in a quasi-stead-state bioreactor. Model solution results showed TCE to be a competitive inhibitor of ammonia oxidation, with TCE affinity for ammonia monooxygenase (AMO) being about four times greater than that of ammonia for the enzyme. Inhibition was independent of TCE oxidation and occurred essentially instantly upon exposure to TCE. In contrast, inactivation of AMO occurred more gradually and was proportional to the rate and amount of TCE oxidized. Evaluation of other O{sub 2}-dependent enzymes and electron transport proteins suggested that TCE-related damage was predominantly confined to AMO. In response to inhibition and/or inactivation, bacterial recovery was initiated, even in the presence of TCE, implying that membranes and protein synthesis systems were functioning.

  16. An explicit expression for determining cometabolism kinetics using progress curve analysis.

    PubMed

    Goudar, Chetan T

    2012-05-31

    We present an explicit expression for describing the kinetics of cometabolic biotransformation of environmental pollutants. This expression is based on the Lambert W function and explicitly relates the substrate concentration, S, to time, t, the two experimentally measured variables. This explicit relationship simplifies kinetic parameter estimation as differential equation solution and iterative estimation of the substrate concentration are eliminated. The applicability of this new expression for nonlinear kinetic parameter estimation was first demonstrated using noise containing synthetic data where final estimates of the kinetic parameters were very close to their actual values. Subsequently 1.1.1-trichloroethane degradation data at initial concentrations of 750 and 375 μM were described using the explicit expression resulting in r and K(s) estimates of 0.26 μM/mg d and 28.08 μM and 0.30 μM/mg d and 28.70 μM, respectively, very similar to 0.276 μM/mg d and 31.2 μM, respectively, that were reported in the original study. The new explicit expression presented in this study simplifies estimation of cometabolic kinetic parameters and can be easily used across all computational platforms thereby providing an attractive alternative for progress curve analysis.

  17. Biodegradation of malathion by Acinetobacter johnsonii MA19 and optimization of cometabolism substrates.

    PubMed

    Xie, Shan; Liu, Junxin; Li, Lin; Qiao, Chuanling

    2009-01-01

    To enhance the removal efficiency of malathion in the wastewater from organophosphate pesticide mill, a bacterium, Acinetobacter johnsonii MA19, that could degrade malathion with cometabolism was isolated from malathion-polluted soil samples using enrichment culture techniques. Four kinds of additional compounds, sodium succinate, sodium acetate, glucose, and fructose were tested to choose a favorite carbon source for the cometabolism of strain MA19. The results showed that sodium succinate and sodium acetate could promote malathion biodegradation and cell growth. The investigation results of the effects of sodium succinate concentrations on the malathion biodegradation indicated that the more sodium succinate supplied resulted in quick degradation of malathion and fast cells multiplied. Zero-order kinetic model was appropriate to describe the malathion biodegradation when the concentration of sodium succinate was more than 0.5144 g/L. The degradation rate constant (K) reached the maximum value of 3.5837 mg/(L x h) when the mass ratio of sodium succinate to malathion was 128.6 mg/mg. The aquatic toxicity of the malathion was evaluated using the test organism, Limnodrilus hoffmeisteri. The data obtained suggested that the toxicity of malathion could be ignored after 84 h biodegradation. Our result demonstrates the potential for using bacterium A. johnsonii MA19 for malathion biodegradation and environmental bioremediation when some suitable conventional carbon sources are supplied.

  18. 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.

  19. Rate limiting factors in trichloroethylene co-metabolic degradation by phenol-grown aerobic granules.

    PubMed

    Zhang, Yi; Tay, Joo Hwa

    2014-04-01

    The potential of aerobic granular sludge in co-metabolic removal of recalcitrant substances was evaluated using trichloroethylene (TCE) as the model compound. Aerobic granules cultivated in a sequencing batch reactor with phenol as the growth substrate exhibited TCE and phenol degradation activities lower than previously reported values. Depletion of reducing energy and diffusion limitation within the granules were investigated as the possible rate limiting factors. Sodium formate and citrate were supplied to the granules in batch studies as external electron sources. No significant enhancing effect was observed on the instant TCE transformation rates, but 10 mM formate could improve the ultimate transformation capacity by 26 %. Possible diffusion barrier was studied by sieving the biomass into five size fractions, and determining their specific TCE and phenol degradation rates and capacities. Biomass in the larger size fractions generally showed lower activities. Large granules of >700 μm diameter exhibited only 22 % of the flocs' TCE transformation capacity and 35 % of its phenol dependent SOUR, indicating the possible occurrence of diffusion limitation in larger biomass. However, the highest specific TCE transformation rate was observed with the fraction that mostly consisted of small granules (150-300 μm), suggesting an optimal size range while applying aerobic granules in TCE co-metabolic removal.

  20. Azo dye treatment with simultaneous electricity production in an anaerobic-aerobic sequential reactor and microbial fuel cell coupled system.

    PubMed

    Li, Zhongjian; Zhang, Xingwang; Lin, Jun; Han, Song; Lei, Lecheng

    2010-06-01

    A microbial fuel cell and anaerobic-aerobic sequential reactor coupled system was used for azo dye degradation with simultaneous electricity production. Electricity was produced during the co-metabolism process of glucose and azo dye. A microorganism cultured graphite-granular cathode effectively decreased the charge transfer resistance of the cathode and yielded higher power density. Operation parameters including glucose concentration and hydraulic retention time were optimized. The results indicated that recovering electricity during a sequential aerobic-anaerobic azo dye treatment process enhanced chemical oxygen demand removal and did not decrease azo dye removal. Moreover, UV-vis spectra and GC-MS illustrated that the azo bond was cleaved biologically in the anaerobic chamber and abiotically in the aerobic chamber. The toxic intermediates, aromatic amines, were removed by aerobic treatment. Our work demonstrated that the microbial fuel cell and sequential anode-cathode reactor coupled system could be applied to achieve electricity production with simultaneous azo dye degradation.

  1. A general model for multiple substrate biodegradation. Application to co-metabolism of structurally non-analogous compounds.

    PubMed

    Brandt, Bernd W; van Leeuwen, Ingeborg M M; Kooijman, Sebastiaan A L M

    2003-12-01

    The availability of multiple carbon/energy sources, as is common in wastewater treatment plants, often enhances the biodegradation of recalcitrant compounds. In this paper, we classify and model different modes of multiple substrate utilization in a systematic way, using the concept of synthesizing unit. According to this concept, substrates can be substitutable or complementary; their uptake (or processing) can be sequential or parallel. We show how the different modes of multiple substrate interaction can be described by a single general model. From the general model, we derive simple expressions for co-metabolism of substrates that are not structurally analogous. Both the general and the specific co-metabolism model have the advantage that they can be used in combination with any microbial growth model. To test the co-metabolism model's realism, we confront it with experimental data. The results attained with the co-metabolism model support that the general model constitutes a useful framework for modeling aspects of multiple substrate utilization.

  2. Cometabolic biodegradation of methyl tert-butyl ether by a soil consortium: Effect of components present in gasoline.

    PubMed

    Garnier, Patrice M.; Auria, Richard

    2000-04-01

    A soil consortium was tested for its ability to degrade reformulated gasoline, containing methyl tert-butyl ether (MTBE). Reformulated gasoline was rapidly degraded to completion. However, MTBE tested alone was not degraded. A screening was carried out to identify compounds in gasoline that participate in cometabolism with MTBE. Aromatic compounds (benzene, toluene, xylenes) and compounds structurally similar to MTBE (tert-butanol, 2,2-dimethylbutane, 2,2,4-trimethylpentane) were unable to cometabolize MTBE. Cyclohexane was resistant to degradation. However, all n-alkanes tested for cometabolic activity (pentane, hexane, heptane) did enable the biodegradation of MTBE. Among the alkanes tested, pentane was the most efficient (200 &mgr;g/day). Upon the depletion of pentane, the consortium stopped degrading MTBE. When the consortium was spiked with pentane, MTBE degradation continued. When the ratio of MTBE to pentane was increased, the amount of MTBE degraded by the consortium was higher. Finally, diethylether was tested for cometabolic degradation with MTBE. Both compounds were degraded, but the process differed from that observed with pentane.

  3. Review on the fate of emerging contaminants during sludge anaerobic digestion.

    PubMed

    Stasinakis, Athanasios S

    2012-10-01

    Several research papers have been published during the last years investigating the occurrence, fate and effects of emerging contaminants (ECs) on sludge anaerobic digestion (AD). Literature review revealed that research has been mainly focused on specific groups of compounds (linear alkylbenzene sulphonates, nonylphenol ethoxylates, some pharmaceuticals, estrogens, phthalates), while there are fewer or no data for others (personal care products, perfluorinated compounds, brominated flame retardants, organotins, benzotriazoles, benzothiazoles, nanoparticles). AD operational parameters (sludge residence time, temperature), sludge characteristics (type of sludge, adaptation on the compound), physicochemical properties of ECs and co-metabolic phenomena seem to affect compounds' biodegradation. The use of sludge pretreatment methods does not seem to enhance ECs removal; whereas encouraging results have been reported when AD was combined with other treatment methods. Future efforts should be focused on better understanding of biotransformation processes and sorption phenomena occurred in anaerobic digesters, as well as on identification of (bio)transformation products.

  4. 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

  5. Anaerobic thermophiles.

    PubMed

    Canganella, Francesco; Wiegel, Juergen

    2014-02-26

    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 definitely

  6. 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

  7. Phenol- and Toluene-Degrading Microbial Populations from an Aquifer in Which Successful Trichloroethene Cometabolism Occurred

    PubMed Central

    Fries, M. R.; Forney, L. J.; Tiedje, J. M.

    1997-01-01

    We characterized the bacterial populations that grew in a Moffett Field, Calif., aquifer following three sequential field tests of phenol- or toluene-driven cometabolism of trichloroethene (TCE). Reducing the toluene and phenol concentrations in most-probable-number (MPN) tubes from 50 to 5 ppm increased the population density measured for these degraders by 1.5 and 1 log units, respectively, suggesting that natural populations might be quite sensitive to these substrates. Phenol and toluene degraders were isolated from the terminal MPN dilution tubes; 63 genetically distinct strains were identified among the 273 phenol- and toluene-degrading isolates obtained. TCE was cometabolized by 60% of the genetically distinct strains. Most strains (57%) grew on both phenol and toluene, and 78% of these strains hybridized to the toluene ortho-monooxygenase (TOM) probe. None of the strains hybridized to probes from the four other toluene oxygenase pathways. Gram-positive strains comprised 30% of the collection; all of these grew on phenol, and 47% of them also grew on toluene, but none hybridized to the TOM probe. Among the gram-negative strains, 86% of those that grew on both toluene and phenol hybridized to the TOM probe, while only 5% of those that were TOM-positive grew on toluene alone. A larger proportion of TCE degraders was found among gram-negative than gram-positive strains and among organisms that grew on phenol than those that grew on toluene. Hybridization of strains to the TOM probe was somewhat predictive of their TCE-cometabolizing ability, especially for strains isolated on toluene, but there was also a significant number (20%) of strains that hybridized to the TOM probe but were poor TCE cooxidizers. No Moffett Field isolates were as effective as Burkholderia cepacia G4 in cooxidizing TCE. Most of the aquifer strains ranged from moderately effective to ineffective in TCE cooxidation. Such populations, however, apparently accounted for the successful phenol

  8. Co-metabolic degradation of dimethoate by Raoultella sp. X1.

    PubMed

    Liang, Yili; Zeng, Fuhua; Qiu, Guanzhou; Lu, Xiangyang; Liu, Xueduan; Gao, Haichun

    2009-06-01

    A bacterium Raoultella sp. X1, based on its 16S rRNA gene sequence, was isolated. Characteristics regarding the bacterial morphology, physiology, and genetics were investigated with an electron microscopy and conventional microbiological techniques. Although the isolate grew and degraded dimethoate poorly when the chemical was used as a sole carbon and energy source, it was able to remove up to 75% of dimethoate via co-metabolism. With a response surface methodology, we optimized carbon, nitrogen and phosphorus concentrations of the media for dimethoate degradation. Raoultella sp. X1 has a potential to be a useful organism for dimethoate degradation and a model strain for studying this biological process at the molecular level.

  9. Systematic prediction of health-relevant human-microbial co-metabolism through a computational framework

    PubMed Central

    Heinken, Almut; Thiele, Ines

    2015-01-01

    The gut microbiota is well known to affect host metabolic phenotypes. The systemic effects of the gut microbiota on host metabolism are generally evaluated via the comparison of germfree and conventional mice, which is impossible to perform for humans. Hence, it remains difficult to determine the impact of the gut microbiota on human metabolic phenotypes. We demonstrate that a constraint-based modeling framework that simulates “germfree” and “ex-germfree” human individuals can partially fill this gap and allow for in silico predictions of systemic human-microbial co-metabolism. To this end, we constructed the first constraint-based host-microbial community model, comprising the most comprehensive model of human metabolism and 11 manually curated, validated metabolic models of commensals, probiotics, pathogens, and opportunistic pathogens. We used this host-microbiota model to predict potential metabolic host-microbe interactions under 4 in silico dietary regimes. Our model predicts that gut microbes secrete numerous health-relevant metabolites into the lumen, thereby modulating the molecular composition of the body fluid metabolome. Our key results include the following: 1. Replacing a commensal community with pathogens caused a loss of important host metabolic functions. 2. The gut microbiota can produce important precursors of host hormone synthesis and thus serves as an endocrine organ. 3. The synthesis of important neurotransmitters is elevated in the presence of the gut microbiota. 4. Gut microbes contribute essential precursors for glutathione, taurine, and leukotrienes. This computational modeling framework provides novel insight into complex metabolic host-microbiota interactions and can serve as a powerful tool with which to generate novel, non-obvious hypotheses regarding host-microbe co-metabolism. PMID:25901891

  10. 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.

  11. 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

  12. Pilot-scale field tests for the methanotrophic technology cometabolic bioreactor demonstration at the Oak Ridge K-25 Site

    SciTech Connect

    Donaldson, T.L.; Lucero, A.J.; Jennings, H.L.; Herbes, S.E.

    1993-06-01

    This report describes a demonstration of cometabolic technology for bioremediation of groundwater contaminated with trichloroethylene (TCE) and other chlorinated and aromatic solvents conducted by Oak Ridge National Laboratory (ORNL). The technology demonstration is located at a seep from the K-1070-C/D Classified Burial Ground at the Oak Ridge K-25 Site. Funding for this demonstration is provided by the US Department of Energy (DOE), Environmental Restoration/Waste Management Program, Office of Technology Development.

  13. 13C Nuclear Magnetic Resonance Studies of Citrate and Glucose Cometabolism by Lactococcus lactis

    PubMed Central

    Ramos, Ana; Jordan, Kieran N.; Cogan, Timothy M.; Santos, Helena

    1994-01-01

    13C nuclear magnetic resonance (13C-NMR) was used to investigate the metabolism of citrate plus glucose and pyruvate plus glucose by nongrowing cells of Lactococcus lactis subsp. lactis 19B under anaerobic conditions. The metabolism of citrate plus glucose during growth was also monitored directly by in vivo NMR. Although pyruvate is a common intermediate metabolite in the metabolic pathways of both citrate and glucose, the origin of the carbon atoms in the fermentation products was determined by using selectively labeled substrates, e.g., [2,4-13C]citrate, [3-13C]pyruvate, and [2-13C]glucose. The presence of an additional substrate caused a considerable stimulation in the rates of substrate utilization, and the pattern of end products was changed. Acetate plus acetoin and butanediol represented more than 80% (molar basis) of the end products of the metabolism of citrate (or pyruvate) alone, but when glucose was also added, 80% of the citrate (or pyruvate) was converted to lactate. This result can be explained by the activation of lactate dehydrogenase by fructose 1,6-bisphosphate, an intermediate in glucose metabolism. The effect of different concentrations of glucose on the metabolism of citrate by dilute cell suspensions was also probed by using analytical methods other than NMR. Pyruvate dehydrogenase (but not pyruvate formate-lyase) was active in the conversion of pyruvate to acetyl coenzyme A. α-Acetolactate was detected as an intermediate metabolite of citrate or pyruvate metabolism, and the labeling pattern of the end products agrees with the α-acetolactate pathway. It was demonstrated that the contribution of the acetyl coenzyme A pathway for the synthesis of diacetyl, should it exist, is lower than 10%. Evidence for the presence of internal carbon reserves in L. lactis is presented. PMID:16349269

  14. 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.

  15. Experimental and kinetic study on the cometabolic biodegradation of phenol and 4-chlorophenol by psychrotrophic Pseudomonas putida LY1.

    PubMed

    Wang, Qing; Li, Yi; Li, Jing; Wang, Yuming; Wang, Chao; Wang, Peifang

    2015-01-01

    This study investigated the kinetics of phenol and 4-chlorophenol (4-CP) biodegradation by a cold-adapted bacteria, Pseudomonas putida LY1, isolated from Songhua River sediment. The results showed that P. putida LY1 cannot grow on 4-CP as a sole carbon source. P. putida LY1 had the potential to cometabolic biodegrade phenol and 4-CP in a wide range of temperature (varying from 5 to 35 °C) with the optimal temperature around 25 °C. Mixture of phenol and 4-CP were completely removed at two 4-CP concentrations (15 and 40 mg/L) over a wide range of phenol (20-400 mg/L) concentrations, whereby the ratio of 4-CP/biomass (S 2/X) was lower than 0.03. The kinetic models of cometabolic biodegradation of phenol and 4-CP were proposed, considering the growth and nongrowth substrate inhibition. These models successfully simulate the processes of cometabolic degradation of phenol and 4-CP.

  16. 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.

  17. Using co-metabolism to accelerate synthetic starch wastewater degradation and nutrient recovery in photosynthetic bacterial wastewater treatment technology.

    PubMed

    Lu, Haifeng; Zhang, Guangming; Lu, Yufeng; Zhang, Yuanhui; Li, Baoming; Cao, Wei

    2016-01-01

    Starch wastewater is a type of nutrient-rich wastewater that contains numerous macromolecular polysaccharides. Using photosynthetic bacteria (PSB) to treat starch wastewater can reduce pollutants and enhance useful biomass production. However, PSB cannot directly degrade macromolecular polysaccharides, which weakens the starch degradation effect. Therefore, co-metabolism with primary substances was employed in PSB wastewater treatment to promote starch degradation. The results indicated that co-metabolism is a highly effective method in synthetic starch degradation by PSB. When malic acid was used as the optimal primary substrate, the chemical oxygen demand, total sugar, macromolecules removal and biomass yield were considerably higher than when primary substances were not used, respectively. Malic acid was the primary substrate that played a highly important role in starch degradation. It promoted the alpha-amylase activity to 46.8 U and the PSB activity, which induced the degradation of macromolecules. The products in the wastewater were ethanol, acetic acid and propionic acid. Ethanol was the primary product throughout the degradation process. The introduction of co-metabolism with malic acid to treat wastewater can accelerate macromolecules degradation and bioresource production and weaken the acidification effect. This method provides another pathway for bioresource recovery from wastewater. This approach is a sustainable and environmentally friendly wastewater treatment technology.

  18. 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.

  19. Anaerobic filters for the treatment of coal gasification wastewater.

    PubMed

    Suidan, M T; Siekerka, G L; Kao, S W; Pfeffer, J T

    1983-06-01

    A process train consisting of the following sequence of unit processes, a berl-saddle-packed anaerobic filter, an expanded bed, granular activated carbon anaerobic filter, and an activated sludge nitrification system was evaluated for the treatment of a synthetically prepared coal gasification wastewater. The first-stage anaerobic filter resulted in very little removal of organic matter and no methane production. Excellent reduction in organic matter occurred in the granular activated carbon anaerobic filter. The removal mechanism was initially adsorptive and near the end of the study, removal of organic matter was primarily through conversion to methane gas. It is felt that the success of the activated carbon anaerobic filter was due to the ability of the activated carbon to sequester some components of the wastewater that were toxic to the mixed culture of anaerobic microorganisms. The activated sludge nitrification system resulted in complete ammonia oxidation and was very efficient in final effluent polishing.

  20. Quinolone activity against anaerobes.

    PubMed

    Appelbaum, P C

    1999-01-01

    The first generation of fluoroquinolones such as ciprofloxacin and ofloxacin are inactive against most anaerobic bacteria. However, some broad-spectrum quinolones, which have recently become clinically available or are under active development, have significant antianaerobic activity. This review summarises the in vitro activity of currently available, as well as experimental, quinolones against clinically significant anaerobic bacteria. Quinolones with low activity against anaerobes include ciprofloxacin, ofloxacin, levofloxacin, fleroxacin, pefloxacin, enoxacin and lomefloxacin. Compounds with intermediate antianaerobic activity include sparfloxacin and grepafloxacin. Trovafloxacin, gatifloxacin and moxifloxacin yield low MICs against most groups of anaerobes. Quinolones with the greatest in vitro activity against anaerobes include clinafloxacin and sitafloxacin (DU-6859a).

  1. Cometabolic mineralization of benzo[a]pyrene caused by hydrocarbon additions to soil

    SciTech Connect

    Kanaly, R.A.; Bartha, R.

    1999-10-01

    The mineralization of [7-{sup 14}C]benzo[a]pyrene (BaP) in soil was investigated in response to additions of individual hydrocarbons, defined hydrocarbon mixtures, crude oil, and crude oil fractions. Neither substantial BaP mineralization nor enrichment of BaP degraders occurred in BaP-spiked soil in the absence of a suitable hydrocarbon supplement. Crude oil, the saturated and aromatic class components of crude oil, the distillates heating oil, jet fuel, and diesel fuel supported up to 60% mineralization of 80 {micro}g [7-{sup 14}C]BaP per gram of soil in 40 d. Neither single hydrocarbons nor defined hydrocarbon mixtures containing normal and branched alkanes, alicyclics, and aromatics supported comparable BaP mineralization. Evolution of {sup 14}CO{sub 2} occurred after lag periods characteristic to specific petroleum products and their concentrations. Time required for microbial proliferation, hydrocarbon toxicity, and competitive inhibition might have contributed to these lag periods, but the complete inhibition of BaP mineralization by diesel-fuel vapors pointed to a dominant role of competitive inhibition. A lack of radiocarbon incorporation into soil biomass from [7-{sup 14}C]BaP indicated that at least the initial steps of BaP biodegradation in soil were cometabolic in nature. Suitable hydrocarbon mixtures not only supported BaP mineralization by serving as primary substrates, but also enhanced BaP bioavailability by dissolving this hydrophobic solid.

  2. 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 NH4Cl (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.

  3. Biofiltration of methyl tert-butyl ether vapors by cometabolism with pentane: modeling and experimental approach.

    PubMed

    Dupasquier, David; Revah, Sergio; Auria, Richard

    2002-01-15

    Degradation of methyl tert-butyl ether (MTBE) vapors by cometabolism with pentane using a culture of pentane-oxidizing bacteria (Pseudomonas aeruginosa) was studied in a 2.4-L biofilter packed with vermiculite, an inert mineral support. Experimental pentane elimination capacity (EC) of approximately 12 g m(-3) h(-1) was obtained for an empty bed residence time (EBRT) of 1.1 h and inlet concentration of 18.6 g m(-3). For these experimental conditions, EC of MTBE between 0.3 and 1.8 g m(-3) h(-1) were measured with inlet MTBE concentration ranging from 1.1 to 12.3 g m(-3). The process was modeled with general mass balance equations that consider a kinetic model describing cross-competitive inhibition between MTBE (cosubstrate) and pentane (substrate). The experimental data of pentane and MTBE removal efficiencies were compared to the theoretical predictions of the model. The predicted pentane and MTBE concentration profiles agreed with the experimental data for steady-state operation. Inhibition by MTBE of the pentane EC was demonstrated. Increasing the inlet pentane concentration improved the EC of MTBE but did not significantly change the EC of pentane. MTBE degradation rates obtained in this study were much lower than those using consortia or pure strains that can mineralize MTBE. Nevertheless, the system can be improved by increasing the active biomass.

  4. Ciprofloxacin toxicity and its co-metabolic removal by a freshwater microalga Chlamydomonas mexicana.

    PubMed

    Xiong, Jiu-Qiang; Kurade, Mayur B; Kim, Jung Rae; Roh, Hyun-Seog; Jeon, Byong-Hun

    2017-02-05

    This study evaluated the toxicity and cellular stresses of ciprofloxacin (CIP) and its co-metabolic removal in a freshwater microalga Chlamydomonas mexicana. The toxicological effects of CIP on C. mexicana were assessed by studying the growth and biochemical characteristics of the microalga including total chlorophyll, carotenoid content, malondialdehyde (MDA) and superoxide dismutase (SOD) activity. The calculated effective concentration (EC50) of CIP on C. mexicana was 65±4mgL(-1) at 96h. The growth of C. mexicana was significantly inhibited at increased concentrations of CIP, showing 36±1, 75±3. and 88±3% inhibition at 40, 60 and 100mgL(-1) CIP, respectively, compared to the control after 11days of cultivation. The total chlorophyll, carotenoid, MDA and SOD activity were significantly increased as a result of relatively high concentrations of CIP stress. C. mexicana showed 13±1% removal of CIP (2mgL(-1)) after 11days of cultivation; however, the addition of an electron donor (sodium acetate, 4gL(-1)) highly enhanced the removal of CIP (2mgL(-1)) by>3-fold after 11days. Kinetic studies showed that removal of CIP followed a first-order model (R(2) 0.94-0.97) with the apparent rate constants (k) ranging from 0.0121 to 0.079 d(-1).

  5. Cometabolic biodegradation of 1,2,3-trichloropropane by propane-oxidizing bacteria.

    PubMed

    Wang, Baixin; Chu, Kung-Hui

    2017-02-01

    1,2,3-Trichloropropane (TCP) is an emerging groundwater pollutant and suspected human carcinogen. TCP, a recalcitrant contaminant, has been detected in the subsurface near TCP manufacture facilities and many superfund sites. Considering the toxicity and the occurence of TCP, there is a need to seek for cost-effective treatment technologies for TCP-contaminated sites. This paper investigated TCP biodegradation by propane-oxidizing bacteria (PrOB) which are known to express propane monooxygenase (PrMO). PrMO can cometabolically degrade many different contaminants. Four PrOB, Rhodococus jostii RHA1, Mycobacterium vaccae JOB5, Rhodococcus rubber ENV425 and one isolate Sphingopyxis sp. AX-A were examined for their ability to degrade TCP. All the four PrOB resting cells were able to degrade TCP. Strain JOB5 exhibited the best TCP degradation ability (vinitial = 9.7 ± 0.7 μg TCP (mg protein)(-1)h(-1)). No TCP was degraded in the presence of acetylene (an inhibitor for PrMO), suggesting that PrMO might be responsible for TCP degradation. Furthermore, competitive inhibition was observed between propane and TCP, and between trichloroethylene (TCE) and TCP.

  6. Final Progress Report: Coupled Biogeochemical Process Evaluation for Conceptualizing Trichloroethylene Cometabolism

    SciTech Connect

    Crawford, Ronald L; Paszczynski, Andrzej J

    2010-02-19

    Our goal within the overall project is to demonstrate the presence and abundance of methane monooxygenases (MMOs) enzymes and their genes within the microbial community of the Idaho National Laboratory (INL) Test Area North (TAN) site. MMOs are thought to be the primary catalysts of natural attenuation of trichloroethylene (TCE) in contaminated groundwater at this location. The actual presence of the proteins making up MMO complexes would provide direct evidence for its participation in TCE degradation. The quantitative estimation of MMO genes and their translation products (sMMO and pMMO proteins) and the knowledge about kinetics and substrate specificity of MMOs will be used to develop mathematical models of the natural attenuation process in the TAN aquifer. The model will be particularly useful in prediction of TCE degradation rate in TAN and possibly in the other DOE sites. Bacteria known as methanotrophs produce a set of proteins that assemble to form methane monooxygenase complexes (MMOs), enzymes that oxidize methane as their natural substrate, thereby providing a carbon and energy source for the organisms. MMOs are also capable of co-metabolically transforming chlorinated solvents like TCE into nontoxic end products such as carbon dioxide and chloride. There are two known forms of methane monooxygenase, a membrane-bound particulate form (pMMO) and a cytoplasmic soluble form (sMMO). pMMO consists of two components, pMMOH (a hydroxylase comprised of 47-, 27-, and 24-kDa subunits) and pMMOR (a reductase comprised of 63 and 8-kDa subunits). sMMO consists of three components: a hydroxylase (protein A-250 kDa), a dimer of three subunits (α2β2γ2), a regulatory protein (protein B-15.8 kDa), and a reductase (protein C-38.6 kDa). All methanotrophs will produce a methanol dehydrogenase to channel the product of methane oxidation (methanol) into the central metabolite formaldehyde. University of Idaho (UI) efforts focused on proteomic analyses using mass

  7. 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.

  8. Potential of Cometabolic Transformation of Polysaccharides and Lignin in Lignocellulose by Soil Actinobacteria

    PubMed Central

    Větrovský, Tomáš; Steffen, Kari Timo; Baldrian, Petr

    2014-01-01

    While it is known that several Actinobacteria produce enzymes that decompose polysaccharides or phenolic compounds in dead plant biomass, the occurrence of these traits in the environment remains largely unclear. The aim of this work was to screen isolated actinobacterial strains to explore their ability to produce extracellular enzymes that participate in the degradation of polysaccharides and their ability to cometabolically transform phenolic compounds of various complexities. Actinobacterial strains were isolated from meadow and forest soils and screened for their ability to grow on lignocellulose. The potential to transform 14C-labelled phenolic substrates (dehydrogenation polymer (DHP), lignin and catechol) and to produce a range of extracellular, hydrolytic enzymes was investigated in three strains of Streptomyces spp. that possessed high lignocellulose degrading activity. Isolated strains showed high variation in their ability to produce cellulose- and hemicellulose-degrading enzymes and were able to mineralise up to 1.1% and to solubilise up to 4% of poplar lignin and to mineralise up to 11.4% and to solubilise up to 64% of catechol, while only minimal mineralisation of DHP was observed. The results confirm the potential importance of Actinobacteria in lignocellulose degradation, although it is likely that the decomposition of biopolymers is limited to strains that represent only a minor portion of the entire community, while the range of simple, carbon-containing compounds that serve as sources for actinobacterial growth is relatively wide. PMID:24551229

  9. 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.

  10. Anaerobic fermentation of beef cattle manure

    NASA Astrophysics Data System (ADS)

    Hashimoto, A. G.; Chen, Y. R.; Varel, V. H.

    1981-01-01

    The conversion of livestock manure and crop residues into methane and a high protein feed ingredient by thermophilic anaerobic fermentation is summarized. The major biological and operational factors involved in methanogenesis are discussed, and a kinetic model that describes the fermentation process is presented. Substrate biodegradability, fermentation temperature, and influent substrate concentration to have significant effects on CH4 production rate. Assessment of the energy requirements for anaerobic fermentation systems showed that the major energy requirement for a thermophilic system was for maintaining the fermenter temperature. The next major energy consumption was due to the mixing of the influent slurry and fermenter liquor. An approach to optimizing anaerobic fermenter s by selecting design criteria that maximize the net energy production per unit cost is presented.

  11. Diacetyl and acetoin production from the co-metabolism of citrate and xylose by Leuconostoc mesenteroides subsp. mesenteroides.

    PubMed

    Schmitt, P; Vasseur, C; Phalip, V; Huang, D Q; Diviès, C; Prévost, H

    1997-06-01

    The co-metabolism of citrate plus xylose by Leuconostoc mesenteroides subsp. mesenteroides results in a growth stimulation, an increase in D-lactate and acetate production and repression of ethanol production. This correlated well with the levels of key enzymes involved. A partial repression of alcohol dehydrogenase and a marked stimulation of acetate kinase were observed. High citrate bioconversion yields in diacetyl plus acetoin were obtained at pH 5.2 in batch (11.5%) or in chemostat (up to 17.4%) culture. In contrast, no diacetyl or acetoin was detected in citrate plus glucose fermentation.

  12. Progress and challenges in developing metabolic footprints from diet in human gut microbial cometabolism.

    PubMed

    Duffy, Linda C; Raiten, Daniel J; Hubbard, Van S; Starke-Reed, Pamela

    2015-05-01

    Homo sapiens harbor trillions of microbes, whose microbial metagenome (collective genome of a microbial community) using omic validation interrogation tools is estimated to be at least 100-fold that of human cells, which comprise 23,000 genes. This article highlights some of the current progress and open questions in nutrition-related areas of microbiome research. It also underscores the metabolic capabilities of microbial fermentation on nutritional substrates that require further mechanistic understanding and systems biology approaches of studying functional interactions between diet composition, gut microbiota, and host metabolism. Questions surrounding bacterial fermentation and degradation of dietary constituents (particularly by Firmicutes and Bacteroidetes) and deciphering how microbial encoding of enzymes and derived metabolites affect recovery of dietary energy by the host are more complex than previously thought. Moreover, it is essential to understand to what extent the intestinal microbiota is subject to dietary control and to integrate these data with functional metabolic signatures and biomarkers. Many lines of research have demonstrated the significant role of the gut microbiota in human physiology and disease. Probiotic and prebiotic products are proliferating in the market in response to consumer demand, and the science and technology around these products are progressing rapidly. With high-throughput molecular technologies driving the science, studying the bidirectional interactions of host-microbial cometabolism, epithelial cell maturation, shaping of innate immune development, normal vs. dysfunctional nutrient absorption and processing, and the complex signaling pathways involved is now possible. Substantiating the safety and mechanisms of action of probiotic/prebiotic formulations is critical. Beneficial modulation of the human microbiota by using these nutritional and biotherapeutic strategies holds considerable promise as next

  13. Progress and Challenges in Developing Metabolic Footprints from Diet in Human Gut Microbial Cometabolism12

    PubMed Central

    Duffy, Linda C; Raiten, Daniel J; Hubbard, Van S; Starke-Reed, Pamela

    2015-01-01

    Homo sapiens harbor trillions of microbes, whose microbial metagenome (collective genome of a microbial community) using omic validation interrogation tools is estimated to be at least 100-fold that of human cells, which comprise 23,000 genes. This article highlights some of the current progress and open questions in nutrition-related areas of microbiome research. It also underscores the metabolic capabilities of microbial fermentation on nutritional substrates that require further mechanistic understanding and systems biology approaches of studying functional interactions between diet composition, gut microbiota, and host metabolism. Questions surrounding bacterial fermentation and degradation of dietary constituents (particularly by Firmicutes and Bacteroidetes) and deciphering how microbial encoding of enzymes and derived metabolites affect recovery of dietary energy by the host are more complex than previously thought. Moreover, it is essential to understand to what extent the intestinal microbiota is subject to dietary control and to integrate these data with functional metabolic signatures and biomarkers. Many lines of research have demonstrated the significant role of the gut microbiota in human physiology and disease. Probiotic and prebiotic products are proliferating in the market in response to consumer demand, and the science and technology around these products are progressing rapidly. With high-throughput molecular technologies driving the science, studying the bidirectional interactions of host-microbial cometabolism, epithelial cell maturation, shaping of innate immune development, normal vs. dysfunctional nutrient absorption and processing, and the complex signaling pathways involved is now possible. Substantiating the safety and mechanisms of action of probiotic/prebiotic formulations is critical. Beneficial modulation of the human microbiota by using these nutritional and biotherapeutic strategies holds considerable promise as next

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

    SciTech Connect

    Alvarez-Cohen, L. ); McCarty, P.L. )

    1991-04-01

    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{sup {minus}1} for resting cells and 1.5 day{sup {minus}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 CF 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.

  15. 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

  16. Anaerobic digestion of marine microalgae in different salinity levels.

    PubMed

    Mottet, Alexis; Habouzit, Frédéric; Steyer, Jean Philippe

    2014-04-01

    In the context of biofuel production from marine microalgae, anaerobic digestion has the potential to make the process more sustainable and to increase energy efficiency. However, the use of salt-containing microalgae organic residues entails the presence of salts which inhibits methanogenesis. The search for suitable anaerobic microbial consortium adapted to saline conditions can boost the anaerobic conversion into methane. The anaerobic digestion performance of three different anaerobic microbial consortia was assessed in batch tests at different salinities between 15 and 150 g L(-1) and for three successive substrate additions. After an acclimation period, the methane (CH4) yield of the halophilic methanogens at 35 g L(-1) of salinity was close to the reference value without salt addition. Above 75 g L(-1) of salinity, methanogenesis was considerably slowed down. The results underline that methane production from halophilic sediment can be envisaged and promoted for practical application at a seawater concentration. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Absence of microbial mineralization of lignin in anaerobic enrichment cultures.

    PubMed Central

    Odier, E; Monties, B

    1983-01-01

    The existence of anaerobic biodegradation of lignin was examined in mixed microflora. Egyptian soil samples, in which rapid mineralization of organic matter takes place in the presence of an important anaerobic microflora, were used to obtain the anaerobic enrichment cultures for this study. Specifically, 14CO2 or [14C]lignin wood was used to investigate the release of labeled gaseous or soluble degradation products of lignin in microbial cultures. No conversion of 14C-labeled lignin to 14CO2 or 14CH4 was observed after 6 months of incubation at 30 degrees C in anaerobic conditions with or without NO3-. A small increase in soluble radioactivity was observed in certain cultures, but it could not be related to the release of catabolic products during the anaerobic biodegradation of lignin. PMID:6639020

  18. Anaerobic digestion as a waste disposal option for American Samoa

    SciTech Connect

    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.

  19. [Degradation kinetics of naphthalene by anaerobic sludge and analysis of the bacterial biodiversity].

    PubMed

    Cao, Xin-Kai; Yang, Qi; Hao, Chun-Bo

    2012-10-01

    For efficient biological treatment of naphthalene in the industrial wastewater, activated anaerobic sludge was collected from a wastewater treatment plant of petroleum industry, and domesticated with naphthalene, naphthalene and lactate as electron donors, respectively. When the removal efficiency of naphthalene reached more than 90% in a domestication cycle, degradation kinetics were investigated in batch reactions with naphthalene, naphthalene and lactate as electron donors, respectively. Meanwhile, the microbial DNA was extracted from the sludge with high naphthalene removal efficiency, the 16S rDNA clone library was built up, and the bacterial community was analyzed. The results indicated that the degradation rate of naphthalene in reaction with naphthalene as the sole electron donor was much lower than that with naphthalene and lactate as electron donors. In both domestication modes, the naphthalene concentration and the time followed the first order reaction kinetics model and the kinetic constant K were 3.5 x 10(-3) h(-1) and 16 x 10(-3) h(-1), respectively. In addition, phylogenetic analysis indicated that the bacterial communities in naphthalene and lactate co-metabolism sludge were mainly composed of Deltaproteobacteria, Thermotogae, Bacteroidetes, Chloroflexi and Unclassified bacteria. Deltaproteobacteria was the main phylum in the sludge. In mature anaerobic activated sludge, Desulfobulbus sp. and Kosmotoga accounted for 24.2% and 21.0%, respectively. Smithella, Syntrophobacter and Levilinea were also found in the bioreactor. The study of the bacteria diversity in the anaerobic sludge is conducive to the optimization of reaction conditions for efficient removal of naphthalene.

  20. 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.

  1. Anaerobic bag culture method.

    PubMed Central

    Rosenblatt, J E; Stewart, P R

    1975-01-01

    In a new method of anaerobic culture, a transparent, gas-impermeable bag is used and the anaerobic environment is established with copper sulfate-saturated steel wool. An Alka-Seltzer tablet generates carbon dioxide. The agar plate surface can be inspected through the bag at any time without interrupting the anaerobic atmosphere or disturbing other specimens. Methylene blue indicator strips are completely reduced by 4 h after the bag is set up and have remained reduced for as long as 3 weeks. Growth of 16 different stock culture anaerobes was generally equivalent by the bag and GasPak jar methods. Yield and growth of anaerobic isolates also were equivalent with 7 of 10 clinical specimens; from the other 3 specimens, 13 isolates were recovered, 5 by both the bag and jar methods and the rest by one method or the other. No consistent differences were found between the anaerobic bag and GasPak jar methods in the yield of anaerobes from clinical specimens. Early growth (24 h of incubation) of anaerobes from one specimen was detected with the bag method. Images PMID:1100671

  2. Anaerobic bag culture method.

    PubMed

    Rosenblatt, J E; Stewart, P R

    1975-06-01

    In a new method of anaerobic culture, a transparent, gas-impermeable bag is used and the anaerobic environment is established with copper sulfate-saturated steel wool. An Alka-Seltzer tablet generates carbon dioxide. The agar plate surface can be inspected through the bag at any time without interrupting the anaerobic atmosphere or disturbing other specimens. Methylene blue indicator strips are completely reduced by 4 h after the bag is set up and have remained reduced for as long as 3 weeks. Growth of 16 different stock culture anaerobes was generally equivalent by the bag and GasPak jar methods. Yield and growth of anaerobic isolates also were equivalent with 7 of 10 clinical specimens; from the other 3 specimens, 13 isolates were recovered, 5 by both the bag and jar methods and the rest by one method or the other. No consistent differences were found between the anaerobic bag and GasPak jar methods in the yield of anaerobes from clinical specimens. Early growth (24 h of incubation) of anaerobes from one specimen was detected with the bag method.

  3. 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

  4. Biodegradation of methyl tert-butyl ether by cometabolism with hexane in biofilters inoculated with Pseudomonas aeruginosa.

    PubMed

    Salazar, Margarita; Morales, Marcia; Revah, Sergio

    2012-01-01

    Biodegradation of methyl tert-butyl ether (MTBE) vapors by cometabolism with gaseous hexane (n-hexane > 95%) was investigated using Pseudomonas aeruginosa utilizing short chain aliphatic hydrocarbon (C(5)-C(8)). Kinetic batch experiments showed that MTBE was degraded even when hexane was completely exhausted with a cometabolic coefficient of 1.06 ± 0.16 mg MTBE mg hexane(-1). Intermediate tert-butyl alcohol (TBA) accumulation was observed followed by its gradual consumption. A maximum MTBE elimination capacity (EC(MAX)) of 35 g m(-3) h(-1) and removal efficiency (RE) of 70% were attained in mineral medium amended biofilters having an empty bed residence time (EBRT) of 1 min. For these experimental conditions, a maximum hexane EC of approximately 60 g m(-3) h(-1) was obtained at a load of 75 g m(-3) h(-1). Experiments under transient conditions revealed a competitive substrate interaction between MTBE and hexane. Biomass densities between 5.8 and 12.6 g L(biofilter) (-1) were obtained. Nevertheless, production of biopolymers caused non-uniform distribution flow rates that reduced the performance. Residence time distribution profiles showed an intermediate dispersion flow rate with a dispersion coefficient of 0.8 cm(2) s(-1).

  5. 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.

  6. Conversational Dominance.

    ERIC Educational Resources Information Center

    Esau, Helmut; Poth, Annette

    Details of conversational behavior can often not be interpreted until the social interaction, including the rights and obligations of the participants, their intent, the topic, etc., has been defined. This paper presents a model of conversation in which the conversational image a person presents in a given conversational situation is a function of…

  7. 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

  8. 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

  9. Anaerobic performance at altitude.

    PubMed

    Coudert, J

    1992-10-01

    Anaerobic metabolism is usually evaluated by the determination of the anaerobic capacity and the maximal anaerobic mechanical external power (Wmax). Conflicting results are reported on anaerobic capacity evaluated by maximal oxygen deficit and debt, and maximal blood lactate concentration during acute or chronic hypoxia (acclimatized subjects). Data on muscle biopsies (lactate concentration, changes in ATP, phosphocreatine and glycogen stores, glycolytic enzyme activities) and the few studies on lactate flux give in most cases evidence of a non-alteration of the anaerobic capacity for altitudes up to 5,500 m. No differences are observed in Wmax measured at high altitudes up to 5,200 m during intense short-term exercises: (1) jumps on a force platform which is a good indicator of alactic Wmax, and (2) 7-10 s sprints (i.e. force-velocity test) which solicit alactic metabolism but also lactic pathway. For exercises of duration equal or more than 30 s (i.e. Wingate test), there are conflicting results because a lower participation of aerobic metabolism during this test at high altitude can interfere with anaerobic performance. In conclusion, we can admit that anaerobic performances are not altered by high altitudes up to 5,200 m if the length of exposure does not exceed 5 weeks. After this period, muscle mass begins to decrease.

  10. Anaerobic digestion for household organics

    SciTech Connect

    Sinclair, R.; Kelleher, M.

    1995-04-01

    Considerable success in using anaerobic technology for processing household organics is being reported by several recently constructed facilities in Europe. Organic residuals collected separately in a Belgian town are processed to produce biogas and a compost-like material in less than one month. The dry anaerobic conversion process (DRANCO) was developed by Organic Waste Systems (OWS) in the 1980s, with the collaboration of Professor Willy Verstraete at the University of Ghent`s Laboratory of Applied Microbial Ecology. The patented process converts solid and semisolid organic residuals into biogas (for energy recovery) and a stable humus like product. The plant has competing odor sources such as the active landfill and the surrounding farmland - in fact, the smell of livestock manure is quite prevalent in this heavily agricultural area. Addition of the nonrecyclable paper fraction to the feedstock improves the carbon/nitrogen ratio, soaks up moisture, and absorbs odor. The entire Brecht facility does not occupy much space and total material retention time at the site is one month, compared to a number of months for aerobic systems. It also has a low staffing requirement, provides energy self-sufficiency, and the final soil enhancement product meets established quality standards.

  11. Laboratory, Field, and Modeling Studies of Aerobic Cometabolism of CAHs by Butane-Utilizing Microorganisms

    NASA Astrophysics Data System (ADS)

    Mathias, M.; Semprini, L.; Dolan, M. E.; McCarty, P. L.; Hopkins, G. D.

    2002-12-01

    The ability of butane-utilizing microorganisms to aerobically cometabolize a mixture of chlorinated aliphatic hydrocarbons (CAHs) in laboratory microcosms and in an in-situ field demonstration was modeled using parameter values measured in laboratory experiments. The butane grown culture was inoculated into soil and groundwater microcosms and exposed to butane with several repeated additions of 1,1,1-trichloroethane (TCA), 1,1-dichloroethylene (1,1-DCE), and 1,1-dichloroethane (1,1-DCA) at aqueous concentrations of 200 μg/L, 100 μg/L, and 200 μg/L, respectively. The utilization of butane and the transformation of the CAH mixture in the batch microcosms were simulated using differential equations accounting for Michaelis-Menten kinetics with cell growth and decay, substrate utilization, transformation product toxicity, and substrate inhibition of CAH transformation. Both competitive inhibition kinetics and mixed inhibition kinetics, determined in prior laboratory studies, were included in the model construct. The equations were solved simultaneously using fourth-order Runge-Kutta numerical integration. The batch microcosm experimental results were simulated well with parameter values determined independently in culture kinetic studies, with some minor adjustments. Having adequately defined the parameter values from laboratory studies, the biotransformation model was combined with 1-D advective-dispersive transport to simulate the results of in-situ bioremediation tests conducted at the Moffett Field Test Facility in CA. The butane-utilizing culture was injected into a 7 m subsurface test site and exposed to alternating pulses of oxygen and butane, along with TCA (150 μg/L), 1,1-DCE (50 μg/L) and 1,1-DCA (150 μg/L). The model simulated well the transient transformation of the CAHs in response to different butane and oxygen pulse cycles and injection concentrations. Model simulations correlated well with field results and indicated that better remediation

  12. Assessing Subsurface Bioaugmentation of a Mixed Culture Capable of Chlorinated Solvent Cometabolism via Molecular Methods

    NASA Astrophysics Data System (ADS)

    Dolan, M. E.; Lim, H. K.; Semprini, L.; Giovanonni, S.; Vergin, K.; McCarty, P. L.; Hopkins, G. D.

    2001-12-01

    The goal of this project is the successful bioaugmentation of a mixed culture capable of aerobic cometabolism of chlorinated solvent mixtures into an aquifer test zone at Moffett Federal Airfield, CA (Moffett). The test zone consists of two parallel well legs both fed butane and oxygen. One leg will be bioaugmented and the other will serve as an indigenous control. Injection and extraction wells and six (3 per leg) intermediately placed groundwater monitoring points will be frequently monitored for chlorinated solvents, butane, dissolved oxygen, and pH. Groundwater will also be periodically analyzed for microbial content using terminal restriction fragment length polymorphism (T-RFLP) and fluorescence in-situ hybridization (FISH) analyses. In each well leg, two fully-penetrating wells containing solid media will be periodically analyzed for microbial colonization (T-RFLP). The mixed bioaugmentation culture originated from environmental samples taken from Hanford, WA. The culture was enriched on butane and tested for viability in Moffett groundwater and aquifer solids. A clone library was created from the 16S rDNA in the mixed culture and 86 clones were sorted based on RFLP patterns. Complete sequencing of the 16S rDNA gene from the three most prevalent clones revealed 45 clones similar to Acidovorax or Hydrogenophaga, gram negative proteobacterium, and 12 clones similar to Rhodococcus, a gram positive filamentous organism. Fluorescently-labeled rRNA probes were designed for FISH analyses and appropriate restriction enzymes were chosen for T-RFLP analyses based upon the sequence information. Microcosm tests were conducted prior to the initiation of the field study to evaluate butane, 1,1-dichloroethylene (1,1-DCE), and 1,1,1-trichloroethane (TCA) degradation kinetics and microbial community composition. Bioaugmented microcosms began butane utilization sooner than non-bioaugmented ones in the presence and absence of 1,1-DCE, and were able to degrade more 1,1-DCE (up

  13. A novel process for anaerobic composting of municipal solid waste

    SciTech Connect

    Chynoweth, D.P.; Bosch, G.; Earle, J.F.K.

    1991-12-31

    A novel process has been developed and evaluated in a pilot-scale program for conversion of the biodegradable fraction of municipal solid waste (MSW) to methane via anaerobic composting. The sequential batch anaerobic composting (SEBAC) process employs leachate management to provide organisms, moisture, and nutrients required for rapid conversion of MSW and removal of inhibitory fermentation products during start-up. The biodegradable organic materials are converted to methane and carbon dioxide in 21-42 d, rather than the years required in landfills.

  14. 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...

  15. 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...

  16. Anaerobic brain abscess

    PubMed Central

    Sudhaharan, Sukanya; Chavali, Padmasri

    2016-01-01

    Background and Objectives: Brain abscess remains a potentially fatal central nervous system (CNS) disease, especially in developing countries. Anaerobic abscess is difficult to diagnose because of cumbersome procedures associated with the isolation of anaerobes. Materials and Methods: This is a hospital-based retrospective microbiological analysis of 430 brain abscess materials (purulent aspirates and/or tissue), for anaerobic organisms, that were received between 1987–2014, by the Microbiology Laboratory in our Institute. Results: Culture showed growth of bacteria 116/430 (27%) of the cases of which anaerobes were isolated in 48/116 (41.1%) of the cases. Peptostreptococcus (51.4 %), was the predominant organism isolated in four cases followed by Bacteroides and Peptococcus species. Conclusion: Early diagnosis and detection of these organisms would help in the appropriate management of these patients. PMID:27307977

  17. Anaerobic digestion of space mission wastes.

    PubMed

    Chynoweth, D P; Owens, J M; Teixeira, A A; Pullammanappallil, P; Luniya, S S

    2006-01-01

    The technical feasibility of applying leachbed high-solids anaerobic digestion for reduction and stabilization of the organic fraction of solid wastes generated during space missions was investigated. This process has the advantages of not requiring oxygen or high temperature and pressure while producing methane, carbon dioxide, nutrients, and compost as valuable products. Anaerobic biochemical methane potential assays run on several waste feedstocks expected during space missions resulted in ultimate methane yields ranging from 0.23 to 0.30 L g-1 VS added. Modifications for operation of a leachbed anaerobic digestion process in space environments were incorporated into a new design, which included; (1) flooded operation to force leachate through densified feedstock beds; and (2) separation of biogas from leachate in a gas collection reservoir. This mode of operation resulted in stable performance with 85% conversion of a typical space solid waste blend, and a methane yield of 0.3 Lg per g VS added after a retention time of 15 days. These results were reproduced in a full-scale prototype system. A detailed analysis of this process was conducted to design the system sized for a space mission with a six-person crew. Anaerobic digestion compared favorably with other technologies for solid waste stabilization.

  18. Kinetics of Methyl t-Butyl Ether Cometabolism at Low Concentrations by Pure Cultures of Butane-Degrading Bacteria

    PubMed Central

    Liu, Catherine Y.; Speitel, Gerald E.; Georgiou, George

    2001-01-01

    Butane-oxidizing Arthrobacter (ATCC 27778) bacteria were shown to degrade low concentrations of methyl t-butyl ether (MTBE; range, 100 to 800 μg/liter) with an apparent half-saturation concentration (Ks) of 2.14 mg/liter and a maximum substrate utilization rate (kc) of 0.43 mg/mg of total suspended solids per day. Arthrobacter bacteria demonstrated MTBE degradation activity when grown on butane but not when grown on glucose, butanol, or tryptose phosphate broth. The presence of butane, tert-butyl alcohol, or acetylene had a negative impact on the MTBE degradation rate. Neither Methylosinus trichosporium OB3b nor Streptomyces griseus was able to cometabolize MTBE. PMID:11319100

  19. Soil aeration to achieve co-metabolic biodegradation of chlorinated solvents in the presence of inducer compounds

    SciTech Connect

    Eisenbeis, J.J.; Bourquin, A.W.

    1995-12-31

    A chemical distribution facility in Denver has been found to have soil and ground water contaminated with a wide variety of organic compounds, primarily toluene and chlorinated solvents, and their breakdown products. Since toluene and chlorobenzenes (both present at the site) have been shown to be inducers for an aerobic enzyme pathway that can degrade trichloroethene (TCE), 1,2-dichloroethene (DCE) and vinyl chloride, field and laboratory studies are being conducted to determine if cometabolic aerobic biodegradation of these and other compounds is occurring in soils that have been aerated with soil vapor extraction (SVE). Studies summarized in this paper include in situ respiration tests to estimate overall biodegradation rate in aerated soils within the influence of a SVE system, sampling to determine if in situ biodegradation of chlorinated volatile organic compounds in ground water has occurred, and a laboratory column study simulating bioventing of unremediated soils.

  20. Co-metabolic degradation of benzo(e)pyrene by halophilic bacterial consortium at different saline conditions.

    PubMed

    Arulazhagan, P; Sivaraman, C; Kumar, S Adish; Aslam, M; Banu, J Rajesh

    2014-05-01

    Polyaromatic hydrocarbons (PAHs) with high molecular weight (more than three benzene rings) were difficult to degrade in saline environment. The present study details about the bacterial consortium enriched from industrial sludge from salt manufacturing company, Tuticorin, Tamilnadu (India), which was capable of degrading 1, 4 dioxane (Emerging micropollutant) and also phenanthrene as sole carbon source under saline condition. The halophilic bacterial consortium was able to degrade low molecular weight (LMW) phenanthrene, but unable to degrade high molecular weight (HMW) benzo(e)pyrene. To overcome this problem, phenanthrene was added as co-substrate along with benzo(e)pyrene which enhanced the biodegradation process by co-metabolism under saline conditions. The consortium potentially degraded 80% and 99% of benzo(e)pyrene in 7 days and phenanthrene in 5 days at 30 g l⁻¹ of NaCl concentration. When the saline concentration increased to 60 g l⁻¹, degradation of phenanthrene (97% in 8 days) and benzo(e)pyrene (65% in 10 days) was observed. Further increase in saline concentration to 90 g I⁻¹ of NaCI showed reduction in the percent degradation of phenanthrene and benzo(e)pyrene leads to 30.3% and 9% respectively in 6 days. Potential bacterial strains, present in PAHs degrading bacterial consortium were identified as Achromobacter sp. AYS3 (JQ419751), Marinobacter sp. AYS4 (JQ419752) and Rhodanobacter sp. AYS5 (JQ419753). The present study details about the effect of salinity on PAHs degradation and vital role of co-metabolism on biodegradation of benzo(e)pyrene with phenanthrene under saline conditions.

  1. Co-metabolism of thiocyanate and free cyanide by Exiguobacterium acetylicum and Bacillus marisflavi under alkaline conditions.

    PubMed

    Mekuto, Lukhanyo; Alegbeleye, Oluwadara Oluwaseun; Ntwampe, Seteno Karabo Obed; Ngongang, Maxwell Mewa; Mudumbi, John Baptist; Akinpelu, Enoch A

    2016-12-01

    The continuous discharge of cyanide-containing effluents to the environment has necessitated for the development of environmentally benign treatment processes that would result in complete detoxification of the cyanide-containing wastewaters, without producing additional environmental toxicants. Since biological detoxification of hazardous chemical compounds has been renowned for its robustness and environmental-friendliness, the ability of the Exiguobacterium acetylicum (GenBank accession number KT282229) and Bacillus marisflavi (GenBank accession number KR016603) to co-metabolise thiocyanate (SCN(-)) and free cyanide (CN(-)) under alkaline conditions was evaluated. E. acetylicum had an SCN(-) degradation efficiency of 99.9 % from an initial SCN(-) concentration of 150 mg SCN(-)/L, but the organism was unable to degrade CN(-). Consequently, B. marisflavi had a CN(-) degradation efficiency of 99 % from an initial concentration of 200 mg CN(-)/L. Similarly, the organism was unable to degrade SCN(-); hence, this resulted in the evaluation of co-metabolism of SCN(-) and CN(-) by the two microbial species. Optimisation of operational conditions was evaluated using response surface methodology (RSM). A numeric optimisation technique was used to evaluate the optimisation of the input variables i.e. pH, temperature, SCN(-) and CN(-) concentrations. The optimum conditions were found to be as follows: pH 9.0, temperature 34 °C, 140 mg SCN(-)/L and 205 mg CN(-)/L under which complete SCN(-) and CN(-) degradation would be achieved over a 168-h period. Using the optimised data, co-metabolism of SCN(-) and CN(-) by both E. acetylicum and B. marisflavi was evaluated, achieving a combined degradation efficiency of ≥99.9 %. The high degradative capacity of these organisms has resulted in their supplementation on an active continuous biological degradation system that is treating both SCN(-) and CN(-).

  2. Changes in fatty acid composition of Stenotrophomonas maltophilia KB2 during co-metabolic degradation of monochlorophenols.

    PubMed

    Nowak, Agnieszka; Greń, Izabela; Mrozik, Agnieszka

    2016-12-01

    The changes in the cellular fatty acid composition of Stenotrophomonas maltophilia KB2 during co-metabolic degradation of monochlorophenols in the presence of phenol as well as its adaptive mechanisms to these compounds were studied. It was found that bacteria were capable of degrading 4-chlorophenol (4-CP) completely in the presence of phenol, while 2-chlorophenol (2-CP) and 3-chlorophenol (3-CP) they degraded partially. The analysis of the fatty acid profiles indicated that adaptive mechanisms of bacteria depended on earlier exposure to phenol, which isomer they degraded, and on incubation time. In bacteria unexposed to phenol the permeability and structure of their membranes could be modified through the increase of hydroxylated and cyclopropane fatty acids, and straight-chain and hydroxylated fatty acids under 2-CP, 3-CP and 4-CP exposure, respectively. In the exposed cells, regardless of the isomer they degraded, the most important changes were connected with the increase of the contribution of branched fatty acid on day 4 and the content of hydroxylated fatty acids on day 7. The changes, particularly in the proportion of branched fatty acids, could be a good indicator for assessing the progress of the degradation of monochlorophenols by S. maltophilia KB2. In comparison, in phenol-degrading cells the increase of cyclopropane and straight-chain fatty acid content was established. These findings indicated the degradative potential of the tested strain towards the co-metabolic degradation of persistent chlorophenols, and extended the current knowledge about the adaptive mechanisms of these bacteria to such chemicals.

  3. Bioaugmentation of an Aerobic Culture Capable of Chlorinated Solvent Cometabolism to a Subsurface Test Zone

    NASA Astrophysics Data System (ADS)

    Dolan, M. E.; Semprini, L.; McCarty, P. L.; Hopkins, G.

    2002-12-01

    A butane-utilizing culture able to cometabolize chlorinated aliphatic hydrocarbons (CAHs) was bioaugmented into an aquifer test zone at Moffett Federal Airfield, CA. Microcosm bioaugmentation tests conducted with groundwater and aquifer solids collected from the test site indicated a strong potential for viability of the bioaugmented culture in the site subsurface. Microcosms bioaugmented with the butane-utilizing culture were able to degrade aqueous concentrations of 1,1-dichloroethylene (1,1-DCE) up to 1 mg/L and could successfully transform mixtures of 1,1-DCE, 1,1,1-trichloroethane (TCA) and 1,1-dichloroethane (DCA) when fed butane. T-RFLP analyses showed the presence of bioaugmented organisms within the microcosms throughout the 10-month test period. An isolate from the butane-utilizing culture was grown in batch bottles containing mineral media and a butane-in-air headspace. Approximately 4 g dry weight of culture was harvested and bioaugmented to the field site. The site consisted of two parallel well legs, each with an injection well, two fully penetrating monitoring wells containing solid support media, three groundwater monitoring wells and an extraction well. One well leg was bioaugmented with the isolate and the other was used as an indigenous control leg. A mixture of 1,1-DCE, TCA and DCA (~50 ug/L, 135 ug/L and 150 ug/L respectively) was continuously pumped through both well legs with alternate pulses of dissolved oxygen and butane. Fifty percent removal of 1,1-DCE occurred within one day in the bioaugmented leg; however, it took about 6 days to achieve complete butane utilization and 1,1-DCE removal to below 2 ug/L. During this period DCA and TCA were reduced by 70- 90 percent and 30-50 percent respectively. When the butane/oxygen pulses were changed from a 1-hr cycle to a 24-hr cycle 1,1-DCE removal fell to 50 percent and DCA and TCA concentrations increased to influent levels. Upon returning to short pulse cycles, 1,1-DCE removal efficiency

  4. Gender comparisons in anaerobic power and anaerobic capacity tests.

    PubMed Central

    Maud, P J; Shultz, B B

    1986-01-01

    The purpose of the study was to compare anaerobic power and anaerobic capacity test scores between young active men and women. Three performance measures of anaerobic power and two of anaerobic capacity were administered to a sample comprising 52 male and 50 female college students (means age = 21.4 yrs). Results indicated significant differences between men and women in body height, weight and per cent fat, in fat free mass (FFM), anaerobic power, and anaerobic capacity when recorded as gross work completed and relative to body weight. However, these differences are reduced when data is adjusted for body weight and further reduced when corrected for FFM. The study found no significant differences between men and women in either anaerobic power or anaerobic capacity when values were given relative to FFM. PMID:3730753

  5. Sulfamethoxazole and ciprofloxacin removal using a horizontal-flow anaerobic immobilized biomass reactor.

    PubMed

    Chatila, Sami; Amparo, Maura R; Carvalho, Lucas S; Penteado, Eduardo D; Tomita, Inês N; Santos-Neto, Álvaro J; Lima Gomes, Paulo C F; Zaiat, Marcelo

    2016-01-01

    The antibiotics sulfamethoxazole (SMTX) and ciprofloxacin (CIP) are commonly used in human and veterinary medicine, which explains their occurrence in wastewater. Anaerobic reactors are low-cost, simple and suitable technology to wastewater treatment, but there is a lack of studies related to the removal efficiency of antibiotics. To overcome this knowledge gap, the objective of this study was to evaluate the removal kinetics of SMTX and CIP using a horizontal-flow anaerobic immobilized biomass reactor. Two different concentrations were evaluated, for SMTX 20 and 40 μg L(-1); for CIP 2.0 and 5.0 μg L(-1). The affluent and effluent analysis was carried out in liquid chromatography/tandem mass spectrometry (LC-MS/MS) with the sample preparation procedure using an off-line solid-phase extraction. This method was developed, validated and successfully applied for monitoring the affluent and effluent samples. The removal efficiency found for both antibiotics at the two concentrations studied was 97%. Chemical oxygen demand (COD) exhibited kinetic constants that were different from that observed for the antibiotics, indicating the absence of co-metabolism. Also, though the antibiotic concentration was increased, there was no inhibitory effect in the removal of COD and antibiotics.

  6. 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.

  7. 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.

  8. 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.

  9. Energetics of Anaerobic Sodium Transport by the Fresh Water Turtle Bladder

    PubMed Central

    Klahr, Saulo; Bricker, Neal S.

    1965-01-01

    Certain of the metabolic events associated with anaerobic sodium transport by the isolated bladder of the fresh water turtle have been investigated. The data suggest that energy for this transport arises from glycolysis and that endogenous glycogen was the major and perhaps the sole source of substrate. The rate of anaerobic glycolysis, as determined by lactate formation, correlates well with the rate as determined by glycogen utilization. Using lactate formation as the index of anaerobic glycolysis, a linear relationship was observed between glycolysis and net anaerobic sodium transport. In the absence of sodium transport, glycolysis decreased by approximately 45 per cent. Tissue ATP concentrations were maintained at about the same level under anaerobic as under aerobic conditions. Finally if it is assumed that in the conversion of glycogen to lactate anaerobically, 3 moles of ATP are generated per mole of glucose residue, an average of over 15 equivalents of sodium were transported for every mole of ATP generated. PMID:14324976

  10. 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.

  11. The anaerobic digestion process

    SciTech Connect

    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 range 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.

  12. Anaerobic digestion process

    SciTech Connect

    Ishida, M.; Haga, R.; Odawara, Y.

    1984-04-10

    First, the organic waste slurry of sewage sludge and/or kitchen garbage is stored in a stable condition after effecting partially thereto a liquefaction treatment in advance by adding liquefying bacteria, and next this slurry is effectively digested anaerobically by way of a liquefaction/gasification-mixed step or a liquefaction/gasification separated step.

  13. Contentious Conversations

    ERIC Educational Resources Information Center

    Zuidema, Leah A.

    2011-01-01

    The idea of joining a conversation through reading and writing is not new; in his 1941 book "The Philosophy of Literary Form: Studies in Symbolic Action," Kenneth Burke suggests that the acts of reading and writing are like entering a parlor where others are already conversing. The author explores the place of professional debate within NCTE and…

  14. Contentious Conversations

    ERIC Educational Resources Information Center

    Zuidema, Leah A.

    2011-01-01

    The idea of joining a conversation through reading and writing is not new; in his 1941 book "The Philosophy of Literary Form: Studies in Symbolic Action," Kenneth Burke suggests that the acts of reading and writing are like entering a parlor where others are already conversing. The author explores the place of professional debate within NCTE and…

  15. Metabolic models to investigate energy limited anaerobic ecosystems.

    PubMed

    Rodríguez, J; Premier, G C; Guwy, A J; Dinsdale, R; Kleerebezem, R

    2009-01-01

    Anaerobic wastewater treatment is shifting from a philosophy of solely pollutants removal to a philosophy of combined resource recovery and waste treatment. Simultaneous wastewater treatment with energy recovery in the form of energy rich products, brings renewed interest to non-methanogenic anaerobic bioprocesses such as the anaerobic production of hydrogen, ethanol, solvents, VFAs, bioplastics and even electricity from microbial fuel cells. The existing kinetic-based modelling approaches, widely used in aerobic and methanogenic wastewater treatment processes, do not seem adequate in investigating such energy limited microbial ecosystems. The great diversity of similar microbial species, which share many of the fermentative reaction pathways, makes quantify microbial groups very difficult and causes identifiability problems. A modelling approach based on the consideration of metabolic reaction networks instead of on separated microbial groups is suggested as an alternative to describe anaerobic microbial ecosystems and in particular for the prediction of product formation as a function of environmental conditions imposed. The limited number of existing relevant fermentative pathways in conjunction with the fact that anaerobic reactions proceed very close to thermodynamic equilibrium reduces the complexity of such approach and the degrees of freedom in terms of product formation fluxes. In addition, energy limitation in these anaerobic microbial ecosystems makes plausible that selective forces associated with energy further define the system activity by favouring those conversions/microorganisms which provide the most energy for growth under the conditions imposed.

  16. Anaerobic benzene oxidation via phenol in Geobacter metallireducens.

    PubMed

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

    2013-12-01

    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 (18)O during growth in H2(18)O, 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.

  17. 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

  18. 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.

  19. Role of surface active media in anaerobic filters

    SciTech Connect

    Khan, K.A.; Suidan, M.T.; Cross, W.H.

    1982-01-01

    Activated C and anthracite coal of the same particle size (10 x 16 mesh) were compared as packing media in completely mixed anaerobic filters. Synthetic glucose- and PhOH-containing solutions and a diluted paint stripping bath wastewater were used as the test substrates. Each wastewater was fed to the two anaerobic filters until stable operating conditions were reached. The granular activated C-packed filter resulted in better COD conversion, higher rates of CH4 production, and lower biomass production than the anthracite-packed filter for all the conditions tested.

  20. 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.

  1. 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.

  2. 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.

  3. Anaerobic digestion of cellulosic wastes

    SciTech Connect

    Donaldson, T.L.; Lee, D.D.

    1984-01-01

    Anaerobic digestion is a potentially attractive technology for volume reduction of cellulosic wastes. A substantial fraction of the waste is converted to off-gas and a relatively small volume of biologically stabilized sludge is produced. Process development work is underway using a 75-L digester to verify rates and conversions obtained at the bench scale, to develop start-up and operating procedures, and to generate effluent for characterization and disposal studies. Three runs using batch and batch-fed conditions have been made lasting 36, 90, and over 200 days. Solids solubilization and gas production rates and total solids destruction have met or exceeded the target values of 0.6 g cellulose per L of reactor per day, 0.5 L off-gas per L of reactor per day, and 80% destruction of solids, respectively. Successful start-up procedures have been developed, and preliminary effluent characterization and disposal studies have been done. A simple dynamic process model has been constructed to aid in further process development and for use in process monitoring and control of a large-scale digester. 7 references, 5 figures, 1 table.

  4. Metric Conversion

    Atmospheric Science Data Center

    2013-03-12

    ... 1,000,000 1,000,000 micrometers nano- 1,000,000,000 1,000,000,000 nanometers ... conversions, see the National Institute of Standards and Technology (NIST) Special Publications: NIST Guide to SI Units: ...

  5. Conversation Analysis.

    ERIC Educational Resources Information Center

    Schiffrin, Deborah

    1990-01-01

    Summarizes the current state of research in conversation analysis, referring primarily to six different perspectives that have developed from the philosophy, sociology, anthropology, and linguistics disciplines. These include pragmatics; speech act theory; interactional sociolinguistics; ethnomethodology; ethnography of communication; and…

  6. Perspectives for anaerobic digestion.

    PubMed

    Ahring, Birgitte K

    2003-01-01

    The modern society generates large amounts of waste that represent a tremendous threat to the environment and human and animal health. To prevent and control this, a range of different waste treatment and disposal methods are used. The choice of method must always be based on maximum safety, minimum environmental impact and, as far as possible, on valorization of the waste and final recycling of the end products. One of the main trends of today's waste management policies is to reduce the stream of waste going to landfills and to recycle the organic material and the plant nutrients back to the soil. Anaerobic digestion (AD) is one way of achieving this goal and it will furthermore, reduce energy consumption or may even be net energy producing. This chapter aims at provide a basic understanding of the world in which anaerobic digestion is operating today. The newest process developments as well as future perspectives will be discussed.

  7. Anaerobic transformation of TNT

    SciTech Connect

    Kulpa, C.F.; Roopathy, R.

    1995-12-31

    Most studies on the microbial metabolism of nitroaromatic compounds have used aerobic tempts to degrade nitroaromatics under aerobic microorganisms. In many cases attempts to degrade nitroaromatics under aerobic conditions results in no mineralization and only superficial modifications of the structure. However, under anaerobic sulfate-reducing conditions, the nitroaromatic compounds undergo a series of reductions with the formation of amino compounds. Trinitrotoluene under sulfate-reducing conditions is reduced to triaminotoluene presumably by the enzyme nitrite reductase, which is commonly found in many Desulfovibrio spp. The removal of nitrate from trinitrotoluene is achieved by a series of reductive reactions with the production of ammonia and toluene by Desulfovibrio sp. (B strain). Similar metabolic processes could be applied to other nitroaromatic compounds like nitrobenzene, nitrobenzoic acids, nitrophenols, and aniline. This presentation will review the data supporting the anaerobic transformation of TNT and other nitroaromatics.

  8. 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

    2017-02-02

    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.

  9. Evaluation of the In Situ Aerobic Cometabolism of Chlorinated Ethenes by Toluene-Utilizing Microorganisms Using Push-Pull Tests

    SciTech Connect

    Azizian, Mohammad F.; Istok, Jonathan; Semprini, Lewis

    2004-03-31

    Single-well-push-pull tests were used in a contaminated aquifer to evaluate the ability of toluene-oxidizing microorganisms to aerobically cometabolize chlorinated aliphatic hydrocarbons (CAHs) such as trichloroethene (TCE). Groundwater containing dissolved toluene was injected into the saturated zone in biostimulate indigenous toluene-utilizers. The test solution was injected into the aquifer using a standard monitoring well and then was transported under natural-gradient conditions. Transport tests demonstrated similar transport characteristics of the conservative tracer and the reactive solutes. Biostimulation tests were then performed by injecting a test solution containing dissolved toluene substrate, hydrogen peroxide, bromide and nitrate in order to increase the biomass of toluene-utilizing microorganisms. During the biostimulation tests, decreases in toluene concentration and the production of o-cresol as an intermediate oxidation product, indicated the simulation of toluene-utilizing microorganisms containing an ortho-monooxygenase enzyme. Transformation tests conducted after biostimulation demonstrated that indigenous microorganisms have the capability to transform the surrogate compounds (e.g. isobutene). Isobutene was transformed to isobutene oxide, indicating transformation by a toluene ortho-monooxygenase.

  10. Fate and cometabolic degradation of benzo[a]pyrene by white-rot fungus Armillaria sp. F022.

    PubMed

    Hadibarata, Tony; Kristanti, Risky Ayu

    2012-03-01

    Armillaria sp. F022, a white-rot fungus isolated from a tropical rain forest in Samarinda, Indonesia, was used to biodegrade benzo[a]pyrene (BaP). Transformation of BaP, a 5-ring polycyclic aromatic hydrocarbon (PAH), by Armillaria sp. F022, which uses BaP as a source of carbon and energy, was investigated. However, biodegradation of BaP has been limited because of its bioavailability and toxicity. Five cosubstrates were selected as cometabolic carbon and energy sources. The results showed that Armillaria sp. F022 used BaP with and without cosubstrates. A 2.5-fold increase in degradation efficiency was achieved after addition of glucose. Meanwhile, the use of glucose as a cosubstrate could significantly stimulate laccase production compared with other cosubstrates and not using any cosubstrate. The metabolic pathway was elucidated by identifying metabolites, conducting biotransformation studies, and monitoring enzyme activities in cell-free extracts. The degradation mechanism was determined through the identification of several metabolites: benzo[a]pyrene-1,6-quinone, 1-hydroxy-2-benzoic acid, and benzoic acid.

  11. Anaerobic digestion process

    SciTech Connect

    Ishida, M.; Haga, R.; Odawara, Y.

    1982-10-19

    An algae culture grown on the water from the digested slurry of a biogasification plant serves as a means of removing CO/sub 2/ from the methane stream while purifying the wastewater and providing more biomass for the anaerobic digestion plant. Tested on a sewage-sludge digestion system, the proposed process improved the methane yield by 32% and methane concentration by 53-98 vol % while lowering the concentration of nitrogen and phosphorus in the final water.

  12. Simple Method for Culturing Anaerobes

    PubMed Central

    Davis, C. E.; Hunter, W. J.; Ryan, J. L.; Braude, A. I.

    1973-01-01

    A simple, effective method is needed for growing obligate anaerobes in the clinical laboratory. This report describes a pre-reduced anaerobic bottle that can be taken to the bedside for direct inoculation, provides a flat agar surface for evaluation of number and morphology of colonies, and can be incubated in conventional bacteriological incubators. Each anaerobic culture set consisted of two bottles containing brain heart infusion agar and CO2. Gentamicin sulfate (50 μg/ml) was added to one of these to inhibit facultative enteric bacilli. Comparison of the anaerobic bottles with an identical aerobic bottle which was also routinely inoculated permitted early identification of anaerobic colonies. Representative species of most anaerobic genera of proven pathogenicity for man have been isolated from this system during 10 months of routine use. Images PMID:4571657

  13. 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.

  14. Microbiology and physiology of anaerobic fermentations of cellulose

    SciTech Connect

    Wiegel, J.

    1991-05-01

    The biochemistry and physiology of four major groups of anaerobic bacteria involved in the conversion of cellulose to methane or chemical feedstocks are examined. Aspects of metabolism which are relevant to the interactions and bioenergetics of consortia are being studied. Properties of the cellulolytic enzyme cluster of Clostridium thermocellum are investigated. Five different hydrogenases have been characterized in detail from anaerobic bacteria. Genes for different hydrogenases are being cloned and sequenced to determine their structural relationships. The role of metal clusters in activation of H{sub 2} is being investigated, as is the structure and role of metal clusters in formate metabolism. The function of formate in the total synthesis of acetate from CO{sub 2} and the role of this primary in anaerobes will be examined as well. Finally, these enzyme studies will be performed on thermophilic bacteria and new, pertinent species will be isolated. 50 refs., 3 figs., 1 tab.

  15. Cometabolic degradation of chlorinated alkenes by alkene monooxygenase in a propylene-grown Xanthobacter strain.

    PubMed Central

    Ensign, S A; Hyman, M R; Arp, D J

    1992-01-01

    Propylene-grown Xanthobacter cells (strain Py2) degraded several chlorinated alkenes of environmental concern, including trichloroethylene, 1-chloroethylene (vinyl chloride), cis- and trans-1,2-dichloroethylene, 1,3-dichloropropylene, and 2,3-dichloropropylene. 1,1-Dichloroethylene was not degraded efficiently, while tetrachloroethylene was not degraded. The role of alkene monooxygenase in catalyzing chlorinated alkene degradations was established by demonstrating that glucose-grown cells which lack alkene monooxygenase and propylene-grown cells in which alkene monooxygenase was selectively inactivated by propyne were unable to degrade the compounds. C2 and C3 chlorinated alkanes were not oxidized by alkene monooxygenase, but a number of these compounds were inhibitors of propylene and ethylene oxidation, suggesting that they compete for binding to the enzyme. A number of metabolites enhanced the rate of degradation of chlorinated alkenes, including propylene oxide, propionaldehyde, and glucose. Propylene stimulated chlorinated alkene oxidation slightly when present at a low concentration but became inhibitory at higher concentrations. Toxic effects associated with chlorinated alkene oxidations were determined by measuring the propylene oxidation and propylene oxide-dependent O2 uptake rates of cells previously incubated with chlorinated alkenes. Compounds which were substrates for alkene monooxygenase exhibited various levels of toxicity, with 1,1-dichloroethylene and trichloroethylene being the most potent inactivators of propylene oxidation and 1,3- and 2,3-dichloropropylene being the most potent inactivators of propylene oxide-dependent O2 uptake. No toxic effects were seen when cells were incubated with chlorinated alkenes anaerobically, indicating that the product(s) of chlorinated alkene oxidation mediates toxicity. PMID:1444418

  16. Energy positive domestic wastewater treatment: the roles of anaerobic and phototrophic technologies.

    PubMed

    Shoener, B D; Bradley, I M; Cusick, R D; Guest, J S

    2014-05-01

    The negative energy balance of wastewater treatment could be reversed if anaerobic technologies were implemented for organic carbon oxidation and phototrophic technologies were utilized for nutrient recovery. To characterize the potential for energy positive wastewater treatment by anaerobic and phototrophic biotechnologies we performed a comprehensive literature review and analysis, focusing on energy production (as kJ per capita per day and as kJ m(-3) of wastewater treated), energy consumption, and treatment efficacy. Anaerobic technologies included in this review were the anaerobic baffled reactor (ABR), anaerobic membrane bioreactor (AnMBR), anaerobic fluidized bed reactor (AFB), upflow anaerobic sludge blanket (UASB), anaerobic sequencing batch reactor (ASBR), microbial electrolysis cell (MEC), and microbial fuel cell (MFC). Phototrophic technologies included were the high rate algal pond (HRAP), photobioreactor (PBR), stirred tank reactor, waste stabilization pond (WSP), and algal turf scrubber (ATS). Average energy recovery efficiencies for anaerobic technologies ranged from 1.6% (MFC) to 47.5% (ABR). When including typical percent chemical oxygen demand (COD) removals by each technology, this range would equate to roughly 40-1200 kJ per capita per day or 110-3300 kJ m(-3) of treated wastewater. The average bioenergy feedstock production by phototrophic technologies ranged from 1200-4700 kJ per capita per day or 3400-13 000 kJ m(-3) (exceeding anaerobic technologies and, at times, the energetic content of the influent organic carbon), with usable energy production dependent upon downstream conversion to fuels. Energy consumption analysis showed that energy positive anaerobic wastewater treatment by emerging technologies would require significant reductions of parasitic losses from mechanical mixing and gas sparging. Technology targets and critical barriers for energy-producing technologies are identified, and the role of integrated anaerobic and

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

    PubMed Central

    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. PMID:27898684

  18. 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.

  19. Growth and anaerobic digestion characteristics of microalgae cultivated using various types of sewage.

    PubMed

    Hidaka, Taira; Inoue, Kenichiro; Suzuki, Yutaka; Tsumori, Jun

    2014-10-01

    Microalgal cultivation combined with anaerobic digestion at wastewater treatment plants is promising to recover energy. This study investigated the growth and anaerobic digestion characteristics of microalgae cultivated using nutrients in sewage. Microalgae were cultivated using primary effluent, secondary effluent, and dewatering filtrate. Microscopic observation indicated that Chlorella was cultivated using dewatering filtrate of anaerobic digestion without controlling the type of species. Batch anaerobic digestion experiments with digested sludge showed that the methane conversion ratio of the cultivated mixture was approximately 40-65%. Different cultivation time did not affect the microalgal contents. Methane recovery mass was 0.13NL-methane/L-cultivation liquor. The C/N ratio of the cultivated mixture was approximately 3-5, but the apparent ammonia release ratio was smaller than that of sewage sludge during digestion. These results proved the applicability of methane recovery from microalgae cultivated using nutrients included in anaerobically digested sludge. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Anaerobic wastewater treatment using anaerobic baffled bioreactor: a review

    NASA Astrophysics Data System (ADS)

    Hassan, Siti Roshayu; Dahlan, Irvan

    2013-09-01

    Anaerobic wastewater treatment is receiving renewed interest because it offers a means to treat wastewater with lower energy investment. Because the microorganisms involved grow more slowly, such systems require clever design so that the microbes have sufficient time with the substrate to complete treatment without requiring enormous reactor volumes. The anaerobic baffled reactor has inherent advantages over single compartment reactors due to its circulation pattern that approaches a plug flow reactor. The physical configuration of the anaerobic baffled reactor enables significant modifications to be made; resulting in a reactor which is proficient of treating complex wastewaters which presently require only one unit, ultimately significant reducing capital costs. This paper also concerns about mechanism, kinetic and hydrodynamic studies of anaerobic digestion for future application of the anaerobic baffled reactor for wastewater treatment.

  1. 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.

  2. ENZYME ACTIVITY PROBE AND GEOCHEMICAL ASSESSMENT FOR POTENTIAL AEROBIC COMETABOLISM OF TRICHLOROETHENE IN GROUNDWATER OF THE NORTHWEST PLUME, PADUCAH GASEOUS DIFFUSION PLANT, KENTUCKY

    SciTech Connect

    Looney, B; M. Hope Lee, M; S. K. Hampson, S

    2008-06-27

    The overarching objective of the Paducah Gaseous Diffusion Plant (PGDP) enzyme activity probe (EAP) effort is to determine if aerobic cometabolism is contributing to the attenuation of trichloroethene (TCE) and other chlorinated solvents in the contaminated groundwater beneath PGDP. The site-specific objective for the EAP assessment is to identify if key metabolic pathways are present and expressed in the microbial community--namely the pathways that are responsible for degradation of methane and aromatic (e.g. toluene, benzene, phenol) substrates. The enzymes produced to degrade methane and aromatic compounds also break down TCE through a process known as cometabolism. EAPs directly measure if methane and/or aromatic enzyme production pathways are operating and, for the aromatic pathways, provide an estimate of the number of active organisms in the sampled groundwater. This study in the groundwater plumes at PGDP is a major part of a larger scientific effort being conducted by Interstate Technology and Regulatory Council (ITRC), U.S. Department of Energy (DOE) Office of Environmental Management (EM), Savannah River National Laboratory (SRNL), and North Wind Inc. in which EAPs are being applied to contaminated groundwater from diverse hydrogeologic and plume settings throughout the U.S. to help standardize their application as well as their interpretation. While EAP data provide key information to support the site specific objective for PGDP, several additional lines of evidence are being evaluated to increase confidence in the determination of the occurrence of biodegradation and the rate and sustainability of aerobic cometabolism. These complementary efforts include: (1) Examination of plume flowpaths and comparison of TCE behavior to 'conservative' tracers in the plume (e.g., {sup 99}Tc); (2) Evaluation of geochemical conditions throughout the plume; and (3) Evaluation of stable isotopes in the contaminants and their daughter products throughout the plume. If

  3. Bioaugmentation with butane-utilizing microorganisms to promote in situ cometabolic treatment of 1,1,1-trichloroethane and 1,1-dichloroethene

    NASA Astrophysics Data System (ADS)

    Semprini, Lewis; Dolan, Mark E.; Hopkins, Gary D.; McCarty, Perry L.

    2009-01-01

    A field study was performed to evaluate the potential for in-situ aerobic cometabolism of 1,1,1-trichloroethane (1,1,1-TCA) through bioaugmentation with a butane enrichment culture containing predominantly two Rhodococcus sp. strains named 179BP and 183BP that could cometabolize 1,1,1-TCA and 1,1-dicholoroethene (1,1-DCE). Batch tests indicated that 1,1-DCE was more rapidly transformed than 1,1,1-TCA by both strains with 183BP being the most effective organism. This second in a series of bioaugmentation field studies was conducted in the saturated zone at the Moffett Field In Situ Test Facility in California. In the previous test, bioaugmentation with an enrichment culture containing the 183BP strain achieved short term in situ treatment of 1,1-DCE, 1,1,1-TCA, and 1,1-dichloroethane (1,1-DCA). However, transformation activity towards 1,1,1-TCA was lost over the course of the study. The goal of this second study was to determine if more effective and long-term treatment of 1,1,1-TCA could be achieved through bioaugmentation with a highly enriched culture containing 179BP and 183BP strains. Upon bioaugmentation and continuous addition of butane and dissolved oxygen and or hydrogen peroxide as sources of dissolved oxygen, about 70% removal of 1,1,1-TCA was initially achieved. 1,1-DCE that was present as a trace contaminant was also effectively removed (˜ 80%). No removal of 1,1,1-TCA resulted in a control test leg that was not bioaugmented, although butane and oxygen consumption by the indigenous populations was similar to that in the bioaugmented test leg. However, with prolonged treatment, removal of 1,1,1-TCA in the bioaugmented leg decreased to about 50 to 60%. Hydrogen pexoxide (H 2O 2) injection increased dissolved oxygen concentration, thus permitting more butane addition into the test zone, but more effective 1,1,1-TCA treatment did not result. The results showed bioaugmentation with the enrichment cultures was effective in enhancing the cometabolic treatment

  4. Conversational Telugu.

    ERIC Educational Resources Information Center

    Beinstein, Judith; And Others

    The purpose of this text is to develop elementary conversational skills in Telugu. The language materials consist of four types of language learning activities. The first, and most predominant, is the unit microwave cycle. These cycles divide the learning process into two basic phases, the first of which involves mimicry, memorization, and…

  5. Conversational Tamil.

    ERIC Educational Resources Information Center

    Beinstein, Judith; And Others

    The purpose of this text is to develop conversational skills in Tamil. It is to be used as a review of what has been learned in class and not as a teaching device. The language materials consist of four types of language learning activities. The unit microwave cycle divides the learning process into two basic phases. The first phase involves…

  6. Metabolism of Diethyl Ether and Cometabolism of Methyl tert-Butyl Ether by a Filamentous Fungus, a Graphium sp

    PubMed Central

    Hardison, L. K.; Curry, S. S.; Ciuffetti, L. M.; Hyman, M. R.

    1997-01-01

    In this study, evidence for two novel metabolic processes catalyzed by a filamentous fungus, Graphium sp. strain ATCC 58400, is presented. First, our results indicate that this Graphium sp. can utilize the widely used solvent diethyl ether (DEE) as the sole source of carbon and energy for growth. The kinetics of biomass accumulation and DEE consumption closely followed each other, and the molar growth yield on DEE was indistinguishable from that with n-butane. n-Butane-grown mycelia also immediately oxidized DEE without the extracellular accumulation of organic oxidation products. This suggests a common pathway for the oxidation of both compounds. Acetylene, ethylene, and other unsaturated gaseous hydrocarbons completely inhibited the growth of this Graphium sp. on DEE and DEE oxidation by n-butane-grown mycelia. Second, our results indicate that gaseous n-alkane-grown Graphium mycelia can cometabolically degrade the gasoline oxygenate methyl tert-butyl ether (MTBE). The degradation of MTBE was also completely inhibited by acetylene, ethylene, and other unsaturated hydrocarbons and was strongly influenced by n-butane. Two products of MTBE degradation, tert-butyl formate (TBF) and tert-butyl alcohol (TBA), were detected. The kinetics of product formation suggest that TBF production temporally precedes TBA accumulation and that TBF is hydrolyzed both biotically and abiotically to yield TBA. Extracellular accumulation of TBA accounted for only a maximum of 25% of the total MTBE consumed. Our results suggest that both DEE oxidation and MTBE oxidation are initiated by cytochrome P-450-catalyzed reactions which lead to scission of the ether bonds in these compounds. Our findings also suggest a potential role for gaseous n-alkane-oxidizing fungi in the remediation of MTBE contamination. PMID:16535667

  7. Economic viability of anaerobic digestion

    SciTech Connect

    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 of 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.

  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

    2017-09-01

    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.

  9. Diversity of anaerobic halophilic microorganisms

    NASA Astrophysics Data System (ADS)

    Oren, Aharon; Oremland, Roland S.

    2000-12-01

    Life in the presence of high salt concentrations is compatible with life in the absence of oxygen. Halophilic and halotolerant anaerobic prokaryotes are found both in the archaeal and in the bacterial domain, and they display a great metabolic diversity. Many of the representatives of the Halobacteriales (Archaea), which are generally considered aerobes, have the potential of anaerobic growth. Some can use alternative electron acceptors such as nitrate, fumarate, dimethylsulfoxide or trimethylamine-N-oxide Halobacterium salinarum can also grow fermentatively on L-arginine, and bacteriorhodopsin-containing cells may even grow anaerobically, energized by light. Obligatory anaerobic halophilic methanogenic Archaea also exist. The bacterial domain contains many anaerobic halophiles, including sulfate reducers. There is also a group of specialized obligatory anaerobic Bacteria, phylogenetically clustering in the low G + C branch of the Firmicutes. Most representatives of this group (order Haloanaerobiales, families Haloanaerobiaceae and Halobacteroidaceae) are fermentative, using a variety of carbohydrates and amino acids. One species combines the potential for anaerobic growth at high salt concentrations with a preference for high temperatures. Others are homoacetogens; Acetohalobium arabaticum can grow anaerobically as a chemolithotroph, producing acetate from hydrogen and CO2. The Haloanaerobiales accumulate high concentrations of K+ and Cl- in their cytoplasm, thereby showing a strategy of salt adaptation similar to that used by the Halobacteriales. Recently a new representative of the Haloanaerobiales was isolated from bottom sediments of the Dead Sea (strain DSSe1), which grows anaerobically by oxidation of glycerol to acetate and CO2 while reducing selenate to selenite and elementary selenium. Other electron acceptors supporting anaerobic growth of this strain are nitrate and trimethylamine-N-oxide. The versatility of life at high salt concentrations with respect

  10. Reductive dechlorination of tetrachloroethene to cis-1, 2-dichloroethene by a thermophilic anaerobic enrichment culture.

    PubMed

    Kengen, S W; Breidenbach, C G; Felske, A; Stams, A J; Schraa, G; de Vos, W M

    1999-06-01

    Thermophilic anaerobic biodegradation of tetrachloroethene (PCE) was investigated with various inocula from geothermal and nongeothermal areas. Only polluted harbor sediment resulted in a stable enrichment culture that converted PCE via trichloroethene to cis-1, 2-dichloroethene at the optimum temperature of 60 to 65 degrees C. After several transfers, methanogens were eliminated from the culture. Dechlorination was supported by lactate, pyruvate, fructose, fumarate, and malate as electron donor but not by H2, formate, or acetate. Fumarate and L-malate led to the highest dechlorination rate. In the absence of PCE, fumarate was fermented to acetate, H2, CO2, and succinate. With PCE, less H2 was formed, suggesting that PCE competed for the reducing equivalents leading to H2. PCE dechlorination, apparently, was not outcompeted by fumarate as electron acceptor. At the optimum dissolved PCE concentration of approximately 60 microM, a high dechlorination rate of 1.1 micromol h-1 mg-1 (dry weight) was found, which indicates that the dechlorination is not a cometabolic activity. Microscopic analysis of the fumarate-grown culture showed the dominance of a long thin rod. Molecular analysis, however, indicated the presence of two dominant species, both belonging to the low-G+C gram positives. The highest similarity was found with the genus Dehalobacter (90%), represented by the halorespiring organism Dehalobacter restrictus, and with the genus Desulfotomaculum (86%).

  11. Reductive Dechlorination of Tetrachloroethene to cis-1,2-Dichloroethene by a Thermophilic Anaerobic Enrichment Culture

    PubMed Central

    Kengen, Servé W. M.; Breidenbach, Caroline G.; Felske, Andreas; Stams, Alfons J. M.; Schraa, Gosse; de Vos, Willem M.

    1999-01-01

    Thermophilic anaerobic biodegradation of tetrachloroethene (PCE) was investigated with various inocula from geothermal and nongeothermal areas. Only polluted harbor sediment resulted in a stable enrichment culture that converted PCE via trichloroethene to cis-1,2-dichloroethene at the optimum temperature of 60 to 65°C. After several transfers, methanogens were eliminated from the culture. Dechlorination was supported by lactate, pyruvate, fructose, fumarate, and malate as electron donor but not by H2, formate, or acetate. Fumarate and l-malate led to the highest dechlorination rate. In the absence of PCE, fumarate was fermented to acetate, H2, CO2, and succinate. With PCE, less H2 was formed, suggesting that PCE competed for the reducing equivalents leading to H2. PCE dechlorination, apparently, was not outcompeted by fumarate as electron acceptor. At the optimum dissolved PCE concentration of ∼60 μM, a high dechlorination rate of 1.1 μmol h−1 mg−1 (dry weight) was found, which indicates that the dechlorination is not a cometabolic activity. Microscopic analysis of the fumarate-grown culture showed the dominance of a long thin rod. Molecular analysis, however, indicated the presence of two dominant species, both belonging to the low-G+C gram positives. The highest similarity was found with the genus Dehalobacter (90%), represented by the halorespiring organism Dehalobacter restrictus, and with the genus Desulfotomaculum (86%). PMID:10347007

  12. Biotechnological research and development for biomass conversion to chemicals and fuels

    NASA Astrophysics Data System (ADS)

    Villet, R.

    1980-08-01

    Revitalization of the older fermentation industry and development of biotechnology largely based on lignocellulose are proposed. Specific research projects are outlined in these two areas and also for the following: microbial formation of hydrocarbons; methane from anaerobic digestion; lignin; methanol. For cellulose conversion to ethanol the relative merits using added cellulases or, alternatively, direct fermentation with anaerobic thermophiles, are discussed. In selecting suitable feedstocks for biotechnological processes there is a need to use a production extraction conversion system as a basis for evaluation.

  13. Conversational sensing

    NASA Astrophysics Data System (ADS)

    Preece, Alun; Gwilliams, Chris; Parizas, Christos; Pizzocaro, Diego; Bakdash, Jonathan Z.; Braines, Dave

    2014-05-01

    Recent developments in sensing technologies, mobile devices and context-aware user interfaces have made it pos- sible to represent information fusion and situational awareness for Intelligence, Surveillance and Reconnaissance (ISR) activities as a conversational process among actors at or near the tactical edges of a network. Motivated by use cases in the domain of Company Intelligence Support Team (CoIST) tasks, this paper presents an approach to information collection, fusion and sense-making based on the use of natural language (NL) and controlled nat- ural language (CNL) to support richer forms of human-machine interaction. The approach uses a conversational protocol to facilitate a ow of collaborative messages from NL to CNL and back again in support of interactions such as: turning eyewitness reports from human observers into actionable information (from both soldier and civilian sources); fusing information from humans and physical sensors (with associated quality metadata); and assisting human analysts to make the best use of available sensing assets in an area of interest (governed by man- agement and security policies). CNL is used as a common formal knowledge representation for both machine and human agents to support reasoning, semantic information fusion and generation of rationale for inferences, in ways that remain transparent to human users. Examples are provided of various alternative styles for user feedback, including NL, CNL and graphical feedback. A pilot experiment with human subjects shows that a prototype conversational agent is able to gather usable CNL information from untrained human subjects.

  14. Conversational sensemaking

    NASA Astrophysics Data System (ADS)

    Preece, Alun; Webberley, Will; Braines, Dave

    2015-05-01

    Recent advances in natural language question-answering systems and context-aware mobile apps create opportunities for improved sensemaking in a tactical setting. Users equipped with mobile devices act as both sensors (able to acquire information) and effectors (able to act in situ), operating alone or in collectives. The currently- dominant technical approaches follow either a pull model (e.g. Apple's Siri or IBM's Watson which respond to users' natural language queries) or a push model (e.g. Google's Now which sends notifications to a user based on their context). There is growing recognition that users need more flexible styles of conversational interaction, where they are able to freely ask or tell, be asked or told, seek explanations and clarifications. Ideally such conversations should involve a mix of human and machine agents, able to collaborate in collective sensemaking activities with as few barriers as possible. Desirable capabilities include adding new knowledge, collaboratively building models, invoking specific services, and drawing inferences. As a step towards this goal, we collect evidence from a number of recent pilot studies including natural experiments (e.g. situation awareness in the context of organised protests) and synthetic experiments (e.g. human and machine agents collaborating in information seeking and spot reporting). We identify some principles and areas of future research for "conversational sensemaking".

  15. Anaerobic Metabolism of Indoleacetate

    PubMed Central

    Ebenau-Jehle, Christa; Thomas, Markus; Scharf, Gernot; Kockelkorn, Daniel; Knapp, Bettina; Schühle, Karola; Heider, Johann

    2012-01-01

    The anaerobic metabolism of indoleacetate (indole-3-acetic acid [IAA]) in the denitrifying betaproteobacterium Azoarcus evansii was studied. The strain oxidized IAA completely and grew with a generation time of 10 h. Enzyme activities that transformed IAA were present in the soluble cell fraction of IAA-grown cells but were 10-fold downregulated in cells grown on 2-aminobenzoate or benzoate. The transformation of IAA did not require molecular oxygen but required electron acceptors like NAD+ or artificial dyes. The first products identified were the enol and keto forms of 2-oxo-IAA. Later, polar products were observed, which could not yet be identified. The first steps likely consist of the anaerobic hydroxylation of the N-heterocyclic pyrrole ring to the enol form of 2-oxo-IAA, which is catalyzed by a molybdenum cofactor-containing dehydrogenase. This step is probably followed by the hydrolytic ring opening of the keto form, which is catalyzed by a hydantoinase-like enzyme. A comparison of the proteome of IAA- and benzoate-grown cells identified IAA-induced proteins. Owing to the high similarity of A. evansii with strain EbN1, whose genome is known, we identified a cluster of 14 genes that code for IAA-induced proteins involved in the early steps of IAA metabolism. These genes include a molybdenum cofactor-dependent dehydrogenase of the xanthine oxidase/aldehyde dehydrogenase family, a hydantoinase, a coenzyme A (CoA) ligase, a CoA transferase, a coenzyme B12-dependent mutase, an acyl-CoA dehydrogenase, a fusion protein of an enoyl-CoA hydratase and a 3-hydroxyacyl-CoA dehydrogenase, a beta-ketothiolase, and a periplasmic substrate binding protein for ABC transport as well as a transcriptional regulator of the GntR family. Five predicted enzymes form or act on CoA thioesters, indicating that soon after the initial oxidation of IAA and possibly ring opening, CoA thioesters are formed, and the carbon skeleton is rearranged, followed by a CoA-dependent thiolytic

  16. Arsenic, Anaerobes, and Autotrophy.

    NASA Astrophysics Data System (ADS)

    Oremland, R. S.

    2008-12-01

    That microbes have resistance to the toxic arsenic oxyanions arsenite [As(III)] and arsenate [As(V)] has been recognized for some time. More recently it was shown that certain prokaryotes can demonstrate As- dependent growth by conserving the energy gained from the aerobic oxidation of As(III) to As(V), or from the reduction of As(V) to As(III) under anaerobic conditions. During the course of our field studies of two alkaline, hypersaline soda lakes (Mono Lake and Searles Lake, CA) we have discovered several new anaerobic chemo- and photo-autotrophic bacteria that can center their energy gain around the redox reactions between As(III) and As(V). Alkalilimnicola ehrlichii, isolated from the water column of Mono Lake is a nitrate-respiring, As(III)-oxidizing chemoautotroph of the gamma-proteobacteria that has a highly flexible metabolism. It can function either as a facultative anaerobe or as a chemo-autotroph, or as a heterotroph (Hoeft et al., 2007). In contrast, strain MLMS-1 of the delta-proteobacteria was also isolated from Mono Lake, but to date is the first example of an obligate As(V)-respirer that is also an obligate chemo-autotroph, gaining its energy via the oxidation of sulfide to sulfate (Hoeft et al., 2004). Strain SLAS-1, isolated from salt-saturated Searles Lake is a member of the Halananerobiales, and can either grow as a heterotroph (lactate e-donor) or chemo- autotroph (sulfide e-donor) while respiring As(V). The fact that it can achieve this feat at salt-saturation (~ 340 g/L) makes it a true extremophile (Oremland et. al., 2005). Finally, strain PHS-1 isolated from a hot spring on Paoha island in Mono Lake is the first example of a photosynthetic bacterium of the gamma- proteobacteria able to link its growth to As(III)-dependent anoxygenic photosynthesis (Kulp et al., 2008). These novel microbes give us new insights into the evolution of arsenic-based metabolism and their role in the biogeochemical cycling of this toxic element. Hoeft, S.E., et

  17. 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.

  18. Kinetics of the aerobic co-metabolism of 1,1-dichloroethylene by Achromobacter sp.: a novel benzene-grown culture.

    PubMed

    Wang, Shizong; Yang, Qi; Zhang, Luning; Wang, Yeyao

    2014-06-01

    Batch experiments were performed for the aerobic co-metabolism of 1,1-dichloroethylene (1,1-DCE) by Achromobacter sp., identified by gene sequencing of 16S rRNA and grown on benzene. Kinetic models were employed to simulate the co-metabolic degradation of 1,1-DCE, and relevant parameters were obtained by non-linear least squares regression. Benzene at 90 mg L(-1) non-competitively inhibited degradation of 1,1-DCE (from 125 to 1,200 μg L(-1)). The maximum specific utilization (kc) rate and the half-saturation constant (Kc) for 1,1-DCE were 54 ± 0.85 μg h(-1) and 220 ± 6.8 μg L(-1), respectively; the kb and Kb for benzene were 13 ± 0.18 mg h(-1) and 28 ± 0.42 mg L(-1), respectively. This study provides a theoretical basis to predict the natural attenuation when benzene and 1,1-DCE occur as co-contaminants.

  19. Biogas plasticization coupled anaerobic digestion: continuous flow anaerobic pump test results.

    PubMed

    Schimel, Keith A; Boone, David R

    2010-03-01

    In this investigation, the Anaerobic Pump (TAP) and a conventional continuous flow stirred tank reactor (CFSTR) were tested side by side to compare performance. TAP integrates anaerobic digestion (AD) with biogas plasticization-disruption cycle to improve mass conversion to methane. Both prototypes were fed a "real world" 50:50 mixture of waste-activated sludge (WAS) and primary sludge and operated at room temperature (20 degrees Celsius). The quantitative results from three steady states show TAP peaked at 97% conversion of the particulate COD in a system hydraulic residence time (HRT) of only 6 days. It achieved a methane production of 0.32 STP cubic meter CH(4) per kilogram COD fed and specific methane yield of 0.78 m(3) CH(4) per cubic meter per day. This was more than three times the CFSTR specific methane yield (0.22 m(3) CH(4) per cubic meter per day) and more than double the CFSTR methane production (0.15 m(3) CH(4) per kilogram COD fed). A comparative kinetics analysis showed the TAP peak substrate COD removal rate (R (o)) was 2.24 kg COD per cubic meter per day, more than three times the CFSTR substrate removal rate of 0.67 kg COD per cubic meter per day. The three important factors contributing to the superior TAP performance were (1) effective solids capture (96%) with (2) mass recycle and (3) stage II plasticization-disruption during active AD. The Anaerobic Pump (TAP) is a high rate, high efficiency-low temperature microbial energy engine that could be used to improve renewable energy yields from classic AD waste substrates like refuse-derived fuels, treatment plant sludges, food wastes, livestock residues, green wastes and crop residuals.

  20. Anaerobic Origin of Ergothioneine.

    PubMed

    Burn, Reto; Misson, Laëtitia; Meury, Marcel; Seebeck, Florian P

    2017-10-02

    Ergothioneine is a sulfur metabolite that occurs in microorganisms, fungi, plants, and animals. The physiological function of ergothioneine is not clear. In recent years broad scientific consensus has formed around the idea that cellular ergothioneine primarily protects against reactive oxygen species. Herein we provide evidence that this focus on oxygen chemistry may be too narrow. We describe two enzymes from the strictly anaerobic green sulfur bacterium Chlorobium limicola that mediate oxygen-independent biosynthesis of ergothioneine. This anoxic origin suggests that ergothioneine is also important for oxygen-independent life. Furthermore, one of the discovered ergothioneine biosynthetic enzymes provides the first example of a rhodanese-like enzyme that transfers sulfur to non-activated carbon. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. PCB breakdown by anaerobic microorganisms

    SciTech Connect

    Not Available

    1989-03-01

    Recently, altered PCB cogener distribution patterns observed in anaerobic sediment samples from the upper Hudson River are being attributed to biologically mediated reductive dechlorination. The authors report their successful demonstration of biologically mediated reductive dechlorination of an Aroclor mixture. In their investigation, they assessed the ability of microorganisms from PCB-contaminated Hudson River sediments (60-562 ppm PCBs) to dechlorinate Aroclor 1242 under anaerobic conditions by eluting microorganisms from the PCB- contaminated sediments and transferring them to a slurry of reduced anaerobic mineral medium and PCB-free sediments in tightly stoppered bottles. They observed dechlorination to be the most rapid at the highest PCB concentration tried by them.

  2. 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)

  3. 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?

  4. 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)

  5. Anaerobic glycerol production by Saccharomyces cerevisiae strains under hyperosmotic stress.

    PubMed

    Modig, Tobias; Granath, Katarina; Adler, Lennart; Lidén, Gunnar

    2007-05-01

    Glycerol formation is vital for reoxidation of nicotinamide adenine dinucleotide (reduced form; NADH) under anaerobic conditions and for the hyperosmotic stress response in the yeast Saccharomyces cerevisiae. However, relatively few studies have been made on hyperosmotic stress under anaerobic conditions. To study the combined effect of salt stress and anaerobic conditions, industrial and laboratory strains of S. cerevisiae were grown anaerobically on glucose in batch-cultures containing 40 g/l NaCl. The time needed for complete glucose conversion increased considerably, and the specific growth rates decreased by 80-90% when the cells were subjected to the hyperosmotic conditions. This was accompanied by an increased yield of glycerol and other by-products and reduced biomass yield in all strains. The slowest fermenting strain doubled its glycerol yield (from 0.072 to 0.148 g/g glucose) and a nearly fivefold increase in acetate formation was seen. In more tolerant strains, a lower increase was seen in the glycerol and in the acetate, succinate and pyruvate yields. Additionally, the NADH-producing pathway from acetaldehyde to acetate was analysed by overexpressing the stress-induced gene ALD3. However, this had no or very marginal effect on the acetate and glycerol yields. In the control experiments, the production of NADH from known sources well matched the glycerol formation. This was not the case for the salt stress experiments in which the production of NADH from known sources was insufficient to explain the formed glycerol.

  6. 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.

  7. Pulse power enhancement of the anaerobic digester process

    SciTech Connect

    Greene, H.W.

    1996-12-31

    A pilot study of the effects of Pulse Power Processing on an anaerobic digester system was completed at the Decatur Utilities Dry Creek Wastewater Treatment Plant, in Decatur Alabama, in September, 1995. This patented method generates several significant effects when all biosolids material is treated as it enters the anaerobic system. Intense, high peak-power plasma arcs are created, one at each end of the parabolic processing chamber, to produce an amplified synergy of alterations to the digester sludge flowing between them. The millisecond electric discharges generate localized temperatures as high as 30,000 K{degrees}, followed by a rapid cooling of the flowing liquid, which produces acoustic shock waves with pressures approaching 5,000 atmospheres. This destructive force: ruptures many of the cell walls of the bacteria and other single-cell organisms, releasing their vacuole fluids; breaks carbon bonds to form smaller organic compounds; and pulverizes large particle conglomerates, increasing the overall surface area of the solids. These beneficial results serve to boost the nutrient source for the anaerobes in the digester. In conjunction with LTV radiation, the formation of excited chemical radicals (including OH{sup -}), and the changes in ionic charge through alteration of the zeta potential, the bioreactor system is turbocharged to enhance the conversion of volatile biosolids to methane gas, which is the natural respiratory by-product of anaerobic digestion.

  8. 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.

  9. 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.

  10. 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.

  11. Advances towards understanding and engineering direct interspecies electron transfer in anaerobic digestion.

    PubMed

    Barua, Sajib; Dhar, Bipro Ranjan

    2017-11-01

    Direct interspecies electron transfer (DIET) is a recently discovered microbial syntrophy where cell-to-cell electron transfer occurs between syntrophic microbial species. DIET between bacteria and methanogenic archaea in anaerobic digestion can accelerate the syntrophic conversion of various reduced organic compounds to methane. DIET-based syntrophy can naturally occur in some anaerobic digester via conductive pili, however, can be engineered via the addition of various non-biological conductive materials. In recent years, research into understanding and engineering DIET-based syntrophy has emerged with the aim of improving methanogenesis kinetics in anaerobic digestion. This article presents a state-of-art review focusing on the fundamental mechanisms, key microbial players, the role of electrical conductivity, the effectiveness of various conductive additives, the significance of substrate characteristics and organic loading rates in promoting DIET in anaerobic digestion. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Anaerobic degradation of inedible crop residues produced in a controlled ecological life support system

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

    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.

  14. Assessing the Feasibility of In-Situ Aerobic Cometabolism of Chlorinated Solvents by a Single-Well Push-Pull and Natural Gradient Drift Tests in McClellan AFB, CA

    NASA Astrophysics Data System (ADS)

    Kim, Y.; Istok, J. D.; Semprini, L.

    2001-12-01

    A single-well push-pull test has been developed to evaluate in-situ aerobic cometabolic treatment of chlorinated aliphatic hydrocarbons (CAHs), such as trichloroethylene (TCE) and cis-1,2-dichloroethylene (c-DCE). A series of single-well natural gradient drift and push-pull tests were conducted in two monitoring wells at the McClellan Air Force Base, CA, where aquifer is contaminated mainly with c-DCE and TCE. Transport characteristics of dissolved solutes [bromide (tracer), propane (growth substrate), ethylene, propylene (nontoxic surrogates to probe for CAH transformation activity), DO and nitrate (nutrient)] were evaluated in push-pull transport tests by injecting 200-L of groundwater containing the solutes into the aquifer (Push), providing a rest period of 18 hours (Reaction), and then extracting 400-L of the test solution/groundwater mixtures (Pull). Mass balances showed over 95% of the injected bromide was recovered, and the recoveries of the other solutes were comparable with bromide. The dispersion of all the solutes was similar indicating sorption or other partitioning processes were minimal. These results indicate that bromide could be used as a conservative tracer for biological activity tests and that little loss of the dissolved gaseous substrates occurred prior to biostimulation of the aquifer. A series of biostimulation tests were performed by injecting 500 L-groundwater containing propane (6 mg/L), DO (25 mg/L), nitrate (9 mg/L as N) and bromide (100 mg/L) into the aquifer. Temporal groundwater samples were obtained from the injection well under natural gradient drift conditions. With repeating biostimulation tests the rates of both propane and DO utilization were increased significantly. The results demonstrated that the progress of biostimulation could be assessed by injecting and monitoring under natural gradient drift conditions. Successive push-pull activity tests were performed after biostimulation was achieved using the same procedures as

  15. Essential metal depletion in an anaerobic reactor.

    PubMed

    Osuna, M B; Iza, J; Zandvoort, M; Lens, P N L

    2003-01-01

    The effect of the absence of trace elements on the conversion of a mixture of volatile fatty acids by a distillery anaerobic granular sludge was investigated. Two UASB reactors were operated under identical operational conditions except for the influent trace metal concentrations, during 140 days. Experiments were carried out in three periods, where different organic loading rates (OLR) were applied to the reactors. The total trace metal concentration steadily decreased at a rate of 48 microg metal/g TS.d in the deprived reactor (down to 35% of their initial value). In contrast, trace metals accumulated in granules present in the control reactor. At the end of the experiment, the COD removal efficiencies were 99% and 77% for the control and deprived reactors, respectively, due to the lack of propionate conversion. Cobalt sorption experiments were carried out in order to study its speciation, and its effects on the speciation of other metals as well. A paper mill wastewater treating granular sludge was also included in the study as a comparison. Results obtained showed that the principal metal forms normally associated with any sludge are a function of each soluble metal concentration in the system, and the characteristics of the particular sludge.

  16. Combination of zero-valent iron and anaerobic microorganisms immobilized in luffa sponge for degrading 1,1,1-trichloroethane and the relevant microbial community analysis.

    PubMed

    Wang, Wenbing; Wu, Yanqing

    2017-01-01

    1,1,1-Trichloroethane (1,1,1-TCA), a dense non-aqueous phase liquid (DNAPL), is relatively slow to remediate naturally; combination of zero-valent iron and immobilized microorganism is a potential means to accelerate DNAPL biodegradation. We first adopted high density luffa sponge (HDLS) as immobilized microorganism carrier. The experimental results demonstrated that (1) the supernatant liquid microorganisms were the optimal immobilized microorganisms for HDLS and (2) the combination of zero-valent iron and immobilized microorganisms accelerated 1,1,1-TCA transformation. Furthermore, in the long-term remediation process, anaerobic microorganisms produced reductant H2S which was beneficial to zero-valent iron PRBs. Through further study of the microbial community, we found that majority of the sulfate-reducing bacteria (SRB) perfectly adapted to the process of 1,1,1-TCA co-metabolism dechlorination. Desulfobulbus and Desulfococcus potentially were the special SRB that contributed significantly to TCA co-metabolism. Additionally, 1,1,1-TCA induced the generation of new SRB and stimulated the growth of majority of dominating methanogens. The results indicated that they played a constructive role in accelerating the dechlorination of 1,1,1-TCA, reduction of sulfate, and improving the production of CH4. Consequently, combination of zero-valent iron and immobilized microorganisms for remediating groundwater by contaminated 1,1,1-TCA is a sustainable and green remediation technology. Especially for groundwater of SO4(2-) type contaminated by 1,1,1-TCA, in the long-term course of combination degradation, cyclic utilization of H2S to prolong the service life of zero-valent iron PRBs. H2 and CH4 generated to capture as potential energy resource. Based on this, a tentative reaction mechanism for Fe(0) biodegradation of 1,1,1-TCA was proposed.

  17. Mechanism of anaerobic degradation of triethanolamine by a homoacetogenic bacterium.

    PubMed

    Speranza, Giovanna; Morelli, Carlo F; Cairoli, Paola; Müller, Britta; Schink, Bernhard

    2006-10-20

    Triethanolamine (TEA) is converted into acetate and ammonia by a strictly anaerobic, gram-positive Acetobacterium strain LuTria3. Fermentation experiments with resting cell suspensions and specifically deuterated substrates indicate that in the acetate molecule the carboxylate and the methyl groups correspond to the alcoholic function and to its adjacent methylene group, respectively, of the 2-hydroxyethyl unit of TEA. A 1,2 shift of a hydrogen (deuterium) atom from -CH2-O- to =N-CH2- without exchange with the medium was observed. This fact gives evidence that a radical mechanism occurs involving the enzyme and/or coenzyme molecule as a hydrogen carrier. Such a biodegradation appears analogous to the conversion of 2-phenoxyethanol into acetate mediated by another strain of the anaerobic homoacetogenic bacterium Acetobacterium.

  18. Mechanism of anaerobic degradation of triethanolamine by a homoacetogenic bacterium

    SciTech Connect

    Speranza, Giovanna . E-mail: giovanna.speranza@unimi.it; Morelli, Carlo F.; Cairoli, Paola; Mueller, Britta; Schink, Bernhard

    2006-10-20

    Triethanolamine (TEA) is converted into acetate and ammonia by a strictly anaerobic, gram-positive Acetobacterium strain LuTria3. Fermentation experiments with resting cell suspensions and specifically deuterated substrates indicate that in the acetate molecule the carboxylate and the methyl groups correspond to the alcoholic function and to its adjacent methylene group, respectively, of the 2-hydroxyethyl unit of TEA. A 1,2 shift of a hydrogen (deuterium) atom from -CH{sub 2} -O- to =N-CH{sub 2} - without exchange with the medium was observed. This fact gives evidence that a radical mechanism occurs involving the enzyme and/or coenzyme molecule as a hydrogen carrier. Such a biodegradation appears analogous to the conversion of 2-phenoxyethanol into acetate mediated by another strain of the anaerobic homoacetogenic bacterium Acetobacterium.

  19. Biology of gut anaerobic fungi.

    PubMed

    Bauchop, T

    1989-01-01

    The obligately anaerobic nature of the gut indigenous fungi distinguishes them from other fungi. They are distributed widely in large herbivores, both in the foregut of ruminant-like animals and in the hindgut of hindgut fermenters. Comparative studies indicate that a capacious organ of fermentative digestion is required for their development. These fungi have been assigned to the Neocallimasticaceae, within the chytridiomycete order Spizellomycetales. The anaerobic fungi of domestic ruminants have been studied most extensively. Plant material entering the rumen is rapidly colonized by zoospores that attach and develop into thalli. The anaerobic rumen fungi have been shown to produce active cellulases and xylanases and specifically colonise and grow on plant vascular tissues. Large populations of anaerobic fungi colonise plant fragment in the rumens of cattle and sheep on high-fibre diets. The fungi actively ferment cellulose which results in formation of a mixture of products including acetate, lactate, ethanol, formate, succinate, CO2 and H2. The properties of the anaerobic fungi together with the extent of their populations on plant fragments in animals on high-fibre diets indicates a significant role for the fungi in fibre digestion.

  20. 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

  1. The microbiology and physiology of anaerobic fermentations of cellulose: Progress report, November 1988--July 1989

    SciTech Connect

    Peck, H.D. Jr.; Ljungdahl, L.G.; Mortenson, L.E.; Wiegel, J.K.W.

    1989-01-01

    In this progress report we describe an integrated study of some individual anaerobic bacteria that are important for the complete conversion of cellulose to methane and CO/sub 2/, and of enzymes such as formate dehydrogenase, hydrogenase and CO dehydrogenase which are of special concern to syntropic interactions between the bacteria.

  2. A batch kinetic study on decolorization and inhibition of Reactive Black 5 and Direct Brown 2 in an anaerobic mixed culture.

    PubMed

    Işik, Mustafa; Sponza, Delia Teresa

    2004-04-01

    Decolorization and inhibition kinetic characteristics of two azo dyes namely Reactive Black 5 (RB 5) and Direct Brown 2 (DB 2) were investigated with partially granulated anaerobic mixed culture using glucose (3000 mg l(-1) COD) as carbon source and electron donor during batch incubation. Monod, zero-, first-, and second-order reaction kinetic models were tested in order to determine the most suitable rate model of substrate and color removal kinetic. The course of the decolorization and substrate removal process approximates to first-order kinetic model under batch conditions. Decolorization, and substrate removal were achieved effectively under test conditions but ultimate removal of azo dyes and substrate were not observed at high dye concentrations. Aromatic amine and volatile fatty acid accumulation were observed proportionally at a higher azo dye concentration. A competitive kinetic model that describes the anaerobic co-metabolism of increasing RB 5 and DB 2 dye concentrations with glucose as co-substrate has been developed based on the experimental data.

  3. 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.

  4. Carbonic anhydrases of anaerobic microbes.

    PubMed

    Ferry, James G

    2013-03-15

    Carbonic anhydrases (CAs) catalyze the reversible hydration of carbon dioxide to bicarbonate and are abundantly distributed in prokaryotes and eukaryotes. There are five classes (α,β,γ,δ,ζ) with no significant sequence or structural identity among them, a remarkable example of convergent evolution. The β and γ classes predominate in anaerobic microbes, living without O2, that comprise a substantial portion of the living protoplasm on Earth. Anaerobes reside in the lower intestinal tract of humans, one of many O2-free environments on Earth, where they convert complex biomass to methane and CO2 contributing an essential link in the global carbon cycle. Carbon dioxide is a universal metabolite of anaerobes necessitating CA for a diversity of proposed functions. Copyright © 2012 Elsevier Ltd. All rights reserved.

  5. The Transition from Aerobic to Anaerobic Metabolism.

    ERIC Educational Resources Information Center

    Skinner, James S.; McLellan, Thomas H.

    1980-01-01

    The transition from aerobic to anaerobic metabolism is discussed. More research is needed on different kinds of athletes and athletic activities and how they may affect aerobic and anaerobic metabolisms. (CJ)

  6. The Transition from Aerobic to Anaerobic Metabolism.

    ERIC Educational Resources Information Center

    Skinner, James S.; McLellan, Thomas H.

    1980-01-01

    The transition from aerobic to anaerobic metabolism is discussed. More research is needed on different kinds of athletes and athletic activities and how they may affect aerobic and anaerobic metabolisms. (CJ)

  7. Arsenic, Anaerobes, and Astrobiology

    NASA Astrophysics Data System (ADS)

    Stolz, J. F.; Oremland, R. S.; Switzer Blum, J.; Hoeft, S. E.; Baesman, S. M.; Bennett, S.; Miller, L. G.; Kulp, T. R.; Saltikov, C.

    2013-12-01

    Arsenic is an element best known for its highly poisonous nature, so it is not something one would associate with being a well-spring for life. Yet discoveries made over the past two decades have delineated that not only are some microbes resistant to arsenic, but that this element's primary redox states can be exploited to conserve energy and support prokaryotic growth ('arsenotrophy') in the absence of oxygen. Hence, arsenite [As(III)] can serve as an electron donor for chemo- or photo-autotrophy while arsenate [As(V)] will serve as an electron acceptor for chemo-heterotrophs and chemo-autotrophs. The phylogenetic diversity of these microbes is broad, encompassing many individual species from diverse taxonomic groups in the Domain Bacteria, with fewer representatives in the Domain Archaea. Speculation with regard to the evolutionary origins of the key functional genes in anaerobic arsenic transformations (arrA and arxA) and aerobic oxidation (aioB) has led to a disputation as to which gene and function is the most ancient and whether arsenic metabolism extended back into the Archaean. Regardless of its origin, robust arsenic metabolism has been documented in extreme environments that are rich in their arsenic content, such as hot springs and especially hypersaline soda lakes associated with volcanic regions. Searles Lake, CA is an extreme, salt-saturated end member where vigorous arsenic metabolism occurs, but there is no detectable sulfate-reduction or methanogenesis. The latter processes are too weak bio-energetically to survive as compared with arsenotrophy, and are also highly sensitive to the abundance of borate ions present in these locales. These observations have implications with respect to the search for microbial life elsewhere in the Solar System where volcanic-like processes have been operative. Hence, because of the likelihood of encountering dense brines in the regolith of Mars (formed by evapo-concentration) or beneath the ice layers of Europa

  8. Anaerobic treatment of food wastes

    SciTech Connect

    Criner, G. )

    1991-04-01

    This article describes a research project at the University of Maine in which food wastes from the University cafeteria salad bar are processed in the anaerobic facility which normally treats only animal wastes. The project has benefited the University in several ways: avoidance of waste disposal fees; increased electricity co-generated from the biogas process; and use of the residual as fertilizer. An economic analysis indicated that the estimated cost of anaerobic treatment of the salad bar wastes was $4520/yr and benefits were $4793/yr. Since the digester was already in use, this cost was not factored into the analysis. Further studies are being planned.

  9. How anaerobic is the Wingate Anaerobic Test for humans?

    PubMed

    Beneke, R; Pollmann, C; Bleif, I; Leithäuser, R M; Hütler, M

    2002-08-01

    The Wingate Anaerobic Test (WAnT) is generally used to evaluate anaerobic cycling performance, but knowledge of the metabolic profile of WAnT is limited. Therefore the energetics of WAnT was analysed with respect to working efficiency and performance. A group of 11 male subjects [mean (SD), age 21.6 (3.8) years, height 178.6 (6.6) cm, body mass 82.2 (12.1) kg] performed a maximal incremental exercise test and a WAnT. Lactic and alactic anaerobic energy outputs were calculated from net lactate production and the fast component of the kinetics of post-exercise oxygen uptake. Aerobic metabolism was determined from oxygen uptake during exercise. The WAnT mean power of 683 (96.0) W resulted from a total energy output above the value at rest of 128.1 (23.2) kJ x 30 s(-1) [mean metabolic power=4.3 (0.8) kW] corresponding to a working efficiency of 16.2 (1.6)%. The WAnT working efficiency was lower (P < 0.01) than the corresponding value of 24.1 (1.7)% at 362 (41) W at the end of an incremental exercise test. During WAnT the fractions of the energy from aerobic, anaerobic alactic and lactic acid metabolism were 18.6 (2.5)%, 31.1 (4.6)%, and 50.3 (5.1)%, respectively. Energy from metabolism of anaerobic lactic acid explained 83% and 81% of the variance of WAnT peak and mean power, respectively. The results indicate firstly that WAnT requires the use of more anaerobically derived energy than previously estimated, secondly that anaerobic metabolism is dominated by glycolysis, thirdly that WAnT mechanical efficiency is lower than that found in aerobic exercise tests, and fourthly that the latter finding partly explains discrepancies between previously published and the present data about the metabolic profile of WAnT.

  10. 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.

  11. 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.

  12. Biological conversion of synthesis gas

    SciTech Connect

    Klasson, K.T.; Basu, R.; Johnson, E.R.; Clausen, E.C.; Gaddy, J.L.

    1992-03-01

    Mass transfer and kinetic studies were carried out for the Rhodospirillum rubrum and Chlorobium thiosulfatophilum bacterial systems. R. rubrum is a photosynthetic anaerobic bacterium which catalyzes the biological water gas shift reaction: CO + H[sub 2]0 [yields] CO[sub 2] + H[sub 2]. C. thiosulfatophilum is also a H[sub 2]S and COS to elemental sulfur. The growth of R. rubrum may be satisfactorily carried out at 25[degree] and 30[degree]C, while CO uptake and thus the conversion of CO best occurs at temperatures of either 30[degree], 32[degree] or 34[degree]C. The rate of conversion of COs and H[sub 2]O to CO[sub 2] and H[sub 2]S may be modeled by a first order rate expression. The rate constant at 30[degree]C was found to be 0.243 h[sup [minus]1]. The growth of C. thiosulfatophilum may be modeled in terms of incoming light intensity using a Monod equation: [mu] = [sub 351] + I[sub o]/[sup 0.152]I[sub o]. Comparisons of the growth of R. rubrum and C. thiosulfatophilum shows that the specific growth rate of C. thiosulfatophilum is much higher at a given light intensity.

  13. Minimal metabolic engineering of Saccharomyces cerevisiae for efficient anaerobic xylose fermentation: a proof of principle.

    PubMed

    Kuyper, Marko; Winkler, Aaron A; van Dijken, Johannes P; Pronk, Jack T

    2004-03-01

    When xylose metabolism in yeasts proceeds exclusively via NADPH-specific xylose reductase and NAD-specific xylitol dehydrogenase, anaerobic conversion of the pentose to ethanol is intrinsically impossible. When xylose reductase has a dual specificity for both NADPH and NADH, anaerobic alcoholic fermentation is feasible but requires the formation of large amounts of polyols (e.g., xylitol) to maintain a closed redox balance. As a result, the ethanol yield on xylose will be sub-optimal. This paper demonstrates that anaerobic conversion of xylose to ethanol, without substantial by-product formation, is possible in Saccharomyces cerevisiae when a heterologous xylose isomerase (EC 5.3.1.5) is functionally expressed. Transformants expressing the XylA gene from the anaerobic fungus Piromyces sp. E2 (ATCC 76762) grew in synthetic medium in shake-flask cultures on xylose with a specific growth rate of 0.005 h(-1). After prolonged cultivation on xylose, a mutant strain was obtained that grew aerobically and anaerobically on xylose, at specific growth rates of 0.18 and 0.03 h(-1), respectively. The anaerobic ethanol yield was 0.42 g ethanol x g xylose(-1) and also by-product formation was comparable to that of glucose-grown anaerobic cultures. These results illustrate that only minimal genetic engineering is required to recruit a functional xylose metabolic pathway in Saccharomyces cerevisiae. Activities and/or regulatory properties of native S. cerevisiae gene products can subsequently be optimised via evolutionary engineering. These results provide a gateway towards commercially viable ethanol production from xylose with S. cerevisiae.

  14. Microbial conversion of biomass to methane

    SciTech Connect

    Chynoweth, D.P.

    1981-01-01

    Laboratory studies have investigated the anaerobic digestion of a variety of feedstocks including sea kelp, water hyacinth, terrestrial herbaceous and woody plants, sewage sludge, municipal solid waste, and biomass-organic waste blends. The results of these and other studies are used to illustrate key factors which influence methane production rates and yields, including feed organic composition, nutrients, inoculum, temperature, retention time, feed concentration, particle size, and mixing. A new process recently developed which combines biological and thermal operations for conversion of biomass to substitute natural gas is described.

  15. Bioconversion of selenate in methanogenic anaerobic granular sludge.

    PubMed

    Astratinei, Violeta; van Hullebusch, Eric; Lens, Piet

    2006-01-01

    The capacity of anaerobic granular sludge to remove selenate from contaminated wastewater was investigated. The potential of different types of granular sludge to remove selenate from the liquid phase was compared to that of suspended sludge and contaminated soil and sediment samples. The selenate removal rates ranged from 400 to 1500 microg g VSS(-1) h(-1), depending on the source of biomass, electron donor, and the initial selenate concentration. The granular structure protects the microorganisms when exposed to high selenate concentrations (0.1 to 1 mM). Anaerobic granular sludge "Eerbeek," originating from a UASB reactor treating paper mill wastewater, removed about 90, 50, and 36% of 0.1, 0.5, and 1 mM of Se, respectively, from the liquid phase when incubated with 20 mM lactate at 30 degrees C and pH 7.5. Selenite, elemental Se (Se(o)), and metal selenide precipitates were the conversion products. Enrichments from the anaerobic granular sludge "Eerbeek" were able to convert 90% of the 10-mM selenate to Se(o) at a rate of 1505 microg Se(VI) g cells(-1) h(-1), a specific growth rate of 0.0125 g cells h(-1), and a yield of 0.083 g cells mg Se(-1). Both microbial metabolic processes (e.g dissimilatory reduction) as well as microbially mediated physicochemical mechanisms (adsorption and precipitation) contribute to the removal of selenate from the Se-containing medium.

  16. 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.

  17. 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

  18. Microbial physiology of an anaerobic propionate-degrading consortium

    SciTech Connect

    Xun, L.

    1989-01-01

    A methanogenic propionate-degrading consortium, comprised of a strictly anaerobic chemoheterotroph and two types of methanogenic bacteria, is responsible for the complete conversion of propionate to CH{sub 4} and CO{sub 2} via the intermediate formation of acetate, H{sub 2}, and CO{sub 2}. Propionate oxidation by the heterotroph to acetate, H{sub 2} and CO{sub 2} proceeds only if H{sub 2} is removed through oxidation by CO{sub 2}-reducing methanogens. Acetate may only be catabolized anaerobically by one specific physiological group of bacteria, the aceticlastic methanogens, which produces CH{sub 4} and CO{sub 2} by cleaving acetate. Representatives of all three of these organisms have been studied. The effects of environmental factors such as temperature, pH, and nutrients on anaerobic propionate degradation was studied by enrichment cultures. From the propionate enrichment, the H{sub 2} using methanogen (strain LX1) and the propionate-degrading organism (strain LX2) were isolated. Both organisms have been characterized. In regard to the aceticlastic reaction, Methanosarcina mazei S-6 isolated by Mah (1980), was studied as the third member of the consortium. By changing the culture conditions, the morphology of M. mazei was manipulated from an aggregated to single cell form.

  19. PGM2 overexpression improves anaerobic galactose fermentation in Saccharomyces cerevisiae

    PubMed Central

    2010-01-01

    Background In Saccharomyces cerevisiae galactose is initially metabolized through the Leloir pathway after which glucose 6-phosphate enters glycolysis. Galactose is controlled both by glucose repression and by galactose induction. The gene PGM2 encodes the last enzyme of the Leloir pathway, phosphoglucomutase 2 (Pgm2p), which catalyses the reversible conversion of glucose 1-phosphate to glucose 6-phosphate. Overexpression of PGM2 has previously been shown to enhance aerobic growth of S. cerevisiae in galactose medium. Results In the present study we show that overexpression of PGM2 under control of the HXT7'promoter from an integrative plasmid increased the PGM activity 5 to 6 times, which significantly reduced the lag phase of glucose-pregrown cells in an anaerobic galactose culture. PGM2 overexpression also increased the anaerobic specific growth rate whereas ethanol production was less influenced. When PGM2 was overexpressed from a multicopy plasmid instead, the PGM activity increased almost 32 times. However, this increase of PGM activity did not further improve aerobic galactose fermentation as compared to the strain carrying PGM2 on the integrative plasmid. Conclusion PGM2 overexpression in S. cerevisiae from an integrative plasmid is sufficient to reduce the lag phase and to enhance the growth rate in anaerobic galactose fermentation, which results in an overall decrease in fermentation duration. This observation is of particular importance for the future development of stable industrial strains with enhanced PGM activity. PMID:20507616

  20. 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.

  1. Cellulose fermentation by nitrogen-fixing anaerobic bacteria

    SciTech Connect

    Canale-Parola, E.

    1992-12-13

    In anaerobic natural environments cellulose is degraded to methane, carbon dioxide and other products by the combined activities of many diverse microorganisms. We are simulating processes occurring in natural environments by constructing biologically-defined, stable, heterogeneous bacterial communities (consortia) that we use as in vitro systems for quantitative studies of cellulose degradation under conditions of combined nitrogen deprivation. These studies include the investigation of (i) metabolic interactions among members of cellulose-degrading microbial populations, and (ii) processes that regulate the activity or biosynthesis of cellulolytic enzymes. In addition, we are studying the sensory mechanisms that, in natural environments, may enable motile cellulolytic bacteria to migrate toward cellulose. This part of our work includes biochemical characterization of the cellobiose chemoreceptor of cellulolytic bacteria. Finally, an important aspect of our research is the investigation of the mechanisms by which multienzyme complexes of anaerobic bacteria catalyze the depolymerization of crystalline cellulose and of other plant cell wall polysacchaddes. The research will provide fundamental information on the physiology and ecology of cellulose-fermenting, N{sub 2}-fixing bacteria, and on the intricate processes involved in C and N cycling in anaerobic environments. Furthermore, the information will be valuable for the development of practical applications, such as the conversion of plant biomass (e.g., agricultural, forestry and municipal wastes) to automotive fuels such as ethanol.

  2. Processing anaerobic sludge for extended storage as anaerobic digester inoculum.

    PubMed

    Li, Jiajia; Zicari, Steven M; Cui, Zongjun; Zhang, Ruihong

    2014-08-01

    Thermophilic anaerobic sludge was processed to reduce the volume and moisture content in order to reduce costs for storing and transporting the sludge as microbial inoculum for anaerobic digester startup. The moisture content of the sludge was reduced from 98.7% to 82.0% via centrifugation and further to 71.5% via vacuum evaporation. The processed sludge was stored for 2 and 4 months and compared with the fresh sludge for the biogas and methane production using food waste and non-fat dry milk as substrates. It was found that fresh unprocessed sludge had the highest methane yield and the yields of both unprocessed and processed sludges decreased during storage by 1-34%, however processed sludges seemed to regain some activity after 4 months of storage as compared to samples stored for only 2 months. Maximum methane production rates obtained from modified Gompertz model application also increased between the 2-month and 4-month processed samples.

  3. 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

  4. An evaluation of the USEPA calculations of greenhouse gas emissions from anaerobic lagoons.

    PubMed

    Lory, John A; Massey, R E; Zulovich, J M

    2010-01-01

    On 10 Apr. 2009, USEPA proposed and on 30 Oct. 2009 USEPA finalized reporting thresholds for a wide range of human-derived sources of greenhouse gas (GHG) as a first step in establishing emission limits in the United States. The only on-farm source category that required monitoring under the proposed and final rule was methane (CH(4)) and nitrous oxide (NO(2)) emissions from manure storage facilities. Our objective was to assess, through a literature review, the methodology used by USEPA to estimate current CH(4) emissions from uncovered anaerobic lagoons and the proposed methodology for reporting those emissions under the proposed rule. A review of the performance of uncovered anaerobic lagoons indicates that they are more effective at degrading volatile solids (VS) than predicted using parameters provided by USEPA that had been developed for anaerobic digesters. We also documented errors in the USEPA- and International Panel on Climate Change-estimated methane conversion factors for uncovered anaerobic lagoons. We suggest estimating CH(4) emissions from anaerobic lagoons based on VS degraded in the lagoon and B' (m(3) CH(4) generated kg(-1) VS destroyed). Our estimate of CH(4) released from uncovered anaerobic lagoons indicated the regulatory operation size threshold could be at least 65% smaller than predicted by USEPA in the proposed rule. Our calculated estimate of CH(4) emissions was substantially greater than the few estimates of CH(4) loss based on direct measurements on uncovered anaerobic lagoons. More research is needed before it will be possible to provide definitive estimates of CH(4) loss from uncovered anaerobic lagoons.

  5. 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

  6. Anaerobic digestion of cellulosic wastes: laboratory tests

    SciTech Connect

    Lee, D.D.; Donaldson, T.L.

    1984-11-01

    Anaerobic digestion is a potentially attractive technology for volume reduction of cellulosic wastes. A substantial fraction of the waste is converted to off-gas and a relatively small volume of biologically stabilized sludge is produced. Process development work is underway using a 75-L digester to verify rates and conversions obtained at the bench scale, to develop start-up and operating procedures, and to generate effluent for characterization and disposal studies. Three runs using batch and batch-fed conditions have been made lasting 36, 90, and over 200 days. Solids solubilization and gas production rates and total solids destruction have met or exceeded the target values of 0.6 g cellulose per L of reactor per day, 0.5 L off-gas per L of reactor per day, and 80% destruction of solids, respectively. Successful start-up procedures have been developed, and preliminary effluent characterization and disposal studies have been done. A simple dynamic process model has been constructed to aid in further process development and for use in process monitoring and control of a large-scale digester. 10 references, 17 figures, 4 tables.

  7. Antibody-catalyzed anaerobic destruction of methamphetamine

    PubMed Central

    Xu, Yang; Hixon, Mark S.; Yamamoto, Noboru; McAllister, Laura A.; Wentworth, Anita D.; Wentworth, Paul; Janda, Kim D.

    2007-01-01

    Methamphetamine [(+)-2] abuse has emerged as a fast-rising global epidemic, with immunopharmacotherapeutic approaches being sought for its treatment. Herein, we report the generation and characterization of a monoclonal antibody, YX1-40H10, that catalyzes the photooxidation of (+)-2 into the nonpsychoactive compound benzaldehyde (14) under anaerobic conditions in the presence of riboflavin (6). Studies have revealed that the antibody facilitates the conversion of (+)-2 into 14 by binding the triplet photoexcited state of 6 in proximity to (+)-2. The antibody binds riboflavin (Kd = 180 μM), although this was not programmed into hapten design, and the YX1-40H10-catalyzed reaction is inhibited by molecular oxygen via the presumed quenching of the photoexcited triplet state of 6. Given that this reaction is another highlight in the processing of reactive intermediates by antibodies, we speculate that this process may have future significance in vivo with programmed immunoglobulins that use flavins as cofactors to destroy selectable molecular targets under hypoxic or even anoxic conditions. PMID:17360412

  8. 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

    2017-04-05

    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.

  9. Anaerobic digestion of aliphatic polyesters.

    PubMed

    Šmejkalová, Pavla; Kužníková, Veronika; Merna, Jan; Hermanová, Soňa

    2016-01-01

    Anaerobic processes for the treatment of plastic materials waste represent versatile and effective approach in environmental protection and solid waste management. In this work, anaerobic biodegradability of model aliphatic polyesters, poly(L-lactic acid) (PLA), and poly(ɛ-caprolactone) (PCL), in the form of powder and melt-pressed films with varying molar mass, was studied. Biogas production was explored in batch laboratory trials at 55 ± 1°C under a nitrogen atmosphere. The inoculum used was thermophilic digested sludge (total solids concentration of 2.9%) from operating digesters at the Central Waste Water Treatment Plant in Prague, Czech Republic. Methanogenic biodegradation of PCLs typically yielded from 54 to 60% of the theoretical biogas yield. The biodegradability of PLAs achieved from 56 to 84% of the theoretical value. High biogas yield (up to 677 mL/g TS) with high methane content (more than 60%), comparable with conventionally processed materials, confirmed the potential of polyester samples for anaerobic treatment in the case of their exploitation in agriculture or as a packaging material in the food industry.

  10. 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.

  11. The extent of co-metabolism of glucose and galactose by Lactococcus lactis changes with the expression of the lacSZ operon from Streptococcus thermophilus.

    PubMed

    Solem, Christian; Koebmann, Brian; Jensen, Peter R

    2008-05-01

    The lactose transporter and beta-galactosidase from Streptococcus thermophilus, encoded by the lacSZ operon, were introduced into the lactose-negative strain Lactococcus lactis MG1363 and the expression of the lacSZ operon was modulated by substitution of the native promoter with randomized synthetic promoters. A series of strains with various expression levels of lacSZ were examined for their fermentation of lactose. Strains with a high expression level were found to metabolize lactose in a similar manner to S. thermophilus, i.e. the galactose moiety of lactose was excreted to the growth medium and only glucose was metabolized in glycolysis. Interestingly, strains with low expression of the operon showed a mixed acid metabolism and co-metabolism of galactose and glucose. The lactose flux increased gradually with increasing expression of the lacSZ operon until an optimum was observed at intermediate beta-galactosidase activities of 2000-3000 Miller units. At higher expression levels, the flux decreased. These strains had a glycolytic flux comparable with those of reference strains with the standard lactococcal PTS(lac) (lactose phosphotransferase transport system) lactose transporter, which indicates that lactose transport is not rate-limiting for glycolysis in Lactococcus. Finally, an additional ATP drain was introduced into the fastest growing strain, CS2004, to test whether the ATP demand controlled glycolysis under these conditions, but in fact no increase in glycolytic flux was observed.

  12. Co-metabolic enhancement of organic removal from waste water in the presence of high levels of alkyl paraben constituents of cosmetic and personal care products.

    PubMed

    Fan, Chihhao; Wang, Shin-Chih

    2017-07-01

    The enhanced removal of organic material from municipal waste water containing 50 mg/L of chemical oxygen demand and a given amount of alkyl paraben using a biofilm system was investigated. The parabens used were methyl, ethyl, and propyl paraben. The experiments were conducted at influent paraben concentrations of 10 and 50 mg/L. The influent pH was measured around 4.6 because of paraben hydrolysis. The effluent pH increased due to hydrogen consumption and small molecular acid generation. The higher removal rates were observed for the paraben with longer alkyl chains, which were more hydrophobic and capable of penetrating into microbial cells. The co-existing organic constituents in municipal waste water were found to be competitive with paraben molecules for microbial degradation at low paraben loading (i.e., 10 mg/L). Instead, the co-metabolic effect was observed at a higher paraben loading (i.e., 50 mg/L) due to more active enzymatic catalysis, implying the possible enhancement or organic removal in the presence of high levels of parabens. The difference in BOD and TOC removing ratios for parabens decreased with increasing HRT, implying their better mineralization than that of municipal organic constituents. This was because the microbial organism became more adapted to the reacting system with longer HRT, and more oxygenase was produced to facilitate the catechol formation and ring-opening reactions, causing apparent enhancement in mineralization. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. 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

    2017-08-04

    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.

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

    SciTech Connect

    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 residues 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.

  15. Express diagnostic of anaerobic infection and disbacteriosis by optical PNC method in clinical dentistry

    NASA Astrophysics Data System (ADS)

    Alexandrov, Michail T.; Koz'ma, Sergey U.; Taubinsky, Ilia M.; Masychev, Victor I.

    2000-11-01

    In this research a new way of express (real time) diagnostics of anaerobic infection and disbacteriosis is suggested. The express diagnostics of anaerobic infection allows to perform quick assessment of the injury microbiocenosis, the state of gastroenteric tract, the disbacteriosis presence and the degree of its development, to follow up dynamics of microflora variations in the process of medication treatment. The research were performed with optical PNC-method. The basic of the method is in registration of stimulated (secondary) radiations and registration of their space fields, which occur in the process of probing radiation interaction with biological tissues and their active elements. The process is called Photon- undulatory Nonlinear Conversion or in short PNC-process (PNC- method, PNC-diagnostic). The optimal diagnostic PNC-method developed here allows detecting the presence of anaerobic microflora directly at the bed of a patient. It makes possible to control the dynamic of patient rehabilitation process, providing strictly individual assessments.

  16. Pashto Conversation Manual and Pashto Conversation Tapescript.

    ERIC Educational Resources Information Center

    Tegey, Habibullah; Robson, Barbara

    This conversation manual and tapescript are part of a set of materials that have been developed to teach oral and written Afghan Pashto to English speakers. In addition to the conversation manual and tapescript, the set consists of a beginning textbook, an intermediate textbook, a reader, and a set of taped lessons that correlate with the…

  17. Increased anaerobic production of methane by co-digestion of sludge with microalgal biomass and food waste leachate.

    PubMed

    Kim, Jungmin; Kang, Chang-Min

    2015-01-01

    The co-digestion of multiple substrates is a promising method to increase methane production during anaerobic digestion. However, limited reliable data are available on the anaerobic co-digestion of food waste leachate with microalgal biomass. This report evaluated methane production by the anaerobic co-digestion of different mixtures of food waste leachate, algal biomass, and raw sludge. Co-digestion of substrate mixture containing equal amounts of three substrates had higher methane production than anaerobic digestion of individual substrates. This was possibly due to a proliferation of methanogens over the entire digestion period induced by multistage digestion of different substrates with different degrees of degradability. Thus, the co-digestion of food waste, microalgal biomass, and raw sludge appears to be a feasible and efficient method for energy conversion from waste resources.

  18. Physiologically anaerobic microorganisms of the deep subsurface

    SciTech Connect

    Stevens, S.E. Jr.; Chung, K.T.

    1991-06-01

    This study seeks to determine numbers, diversity, and morphology of anaerobic microorganisms in 15 samples of subsurface material from the Idaho National Engineering Laboratory, in 18 samples from the Hanford Reservation and in 1 rock sample from the Nevada Test Site; set up long term experiments on the chemical activities of anaerobic microorganisms based on these same samples; work to improve methods for the micro-scale determination of in situ anaerobic microbial activity;and to begin to isolate anaerobes from these samples into axenic culture with identification of the axenic isolates.

  19. Infected Pneumatocele Following Anaerobic Pneumonia in Adult

    PubMed Central

    Chung, Yeon Tae; Lee, Kyung Duk; Seon, Kyoung Youn; Lee, Jong Hyun; Lee, Sung Ho; Choi, Se Ho

    2005-01-01

    We report a case of an infected pneumatocele in the course of anaerobic pneumonia in an adult. To the best of our knowledge, anaerobic pneumonia complicated by a pneumatocele in an adult has not previously been described. The pneumatocele occurred on the fifth day of hospitalization, and rapidly increased in size, with the development of a subsequent mixed anaerobe infection. A pig-tail catheter was inserted and the pus drained. The bacterial culture from the pus was positive for three anaerobes: Bacteroid species, Peptostreptococcus asaccharolyticus and Fusobacterium species. Intravenous antibiotics and percutaneous catheter drainage resulted in a successful treatment. PMID:16491835

  20. Single stage biological nitrogen removal by nitritation and anaerobic ammonium oxidation in biofilm systems.

    PubMed

    Helmer, C; Tromm, C; Hippen, A; Rosenwinkel, K H; Seyfried, C F; Kunst, S

    2001-01-01

    In full scale wastewater treatment plants with at times considerable deficits in the nitrogen balances, it could hitherto not be sufficiently explained which reactions are the cause of the nitrogen losses and which micro-organisms participate in the process. The single stage conversion of ammonium into gaseous end-products--which is henceforth referred to as deammonification--occurs particularly frequently in biofilm systems. In the meantime, one has succeeded to establish the deammonification processes in a continuous flow moving-bed pilot plant. In batch tests with the biofilm covered carriers, it was possible for the first time to examine the nitrogen conversion at the intact biofilm. Depending on the dissolved oxygen (DO) concentration, two autotrophic nitrogen converting reactions in the biofilm could be proven: one nitritation process under aerobic conditions and one anaerobic ammonium oxidation. With the anaerobic ammonium oxidation, ammonium as electron donor was converted with nitrite as electron acceptor. The end-product of this reaction was N2. Ammonium and nitrite did react in a stoichiometrical ratio of 1:1.37, a ratio which has in the very same dimension been described for the ANAMMOX-process (1:1.31 +/- 0.06). Via the oxygen concentration in the surrounding medium, it was possible to control the ratio of nitritation and anaerobic ammonium oxidation in the nitrogen conversion of the biofilm. Both processes were evenly balanced at a DO concentration of 0.7 mg/l, so that it was possible to achieve a direct, almost complete elimination of ammonium without addition of nitrite. One part of the provided ammonium did participate in the nitritation, the other in the anaerobic ammonium oxidation. Through the aerobic ammonium oxidation into nitrite within the outer oxygen supplied layers of the biofilm, the reaction partner was produced for the anaerobic ammonium oxidation within the inner layers of the biofilm.

  1. Random UV-C mutagenesis of Scheffersomyces (formerly Pichia) stipitis NRRL Y-7124 to improve anaerobic growth on lignocellulosic sugars

    USDA-ARS?s Scientific Manuscript database

    Yeast strains for anaerobic conversion of lignocellulosic sugars to ethanol were produced from Scheffersomyces (formerly Pichia) stipitis NRRL Y-7124 using UV-C mutagenesis. Random UV-C mutagenesis potentially produces large numbers of mutations broadly and uniformly over the whole genome to genera...

  2. Anaerobic bacteria from hypersaline environments.

    PubMed Central

    Ollivier, B; Caumette, P; Garcia, J L; Mah, R A

    1994-01-01

    Strictly anaerobic halophiles, namely fermentative, sulfate-reducing, homoacetogenic, phototrophic, and methanogenic bacteria are involved in the oxidation of organic carbon in hypersaline environments. To date, six anaerobic fermentative genera, containing nine species, have been described. Two of them are homoacetogens. Six species belong to the family Haloanaerobiaceae, as indicated by their unique 16S rRNA oligonucleotide sequences. Desulfohalobium retbaense and Desulfovibrio halophilus represent the only two moderately halophilic sulfate reducers so far reported. Among anoxygenic phototrophic anaerobes, a few purple bacteria with optimal growth at salinities between 6 and 11% NaCl have been isolated from hypersaline habitats. They belong to the genera Rhodospirillum, Chromatium, Thiocapsa, and Ectothiorhodospira. The commonest organisms isolated so far are Chromatium salexigens, Thiocapsa halophila, and Rhodospirillum salinarum. Extremely halophilic purple bacteria have most commonly been isolated from alkaline brines and require about 20 to 25% NaCl for optimal growth. They belong to the family Ectothiorodhospiraceae. Their osmoregulation involves synthesis or uptake of compatible solutes such as glycine-betaine that accumulate in their cytoplasm. The existence of methanogens in hypersaline environments is related to the presence of noncompetitive substrates such as methylamines, which originate mainly from the breakdown of osmoregulatory amines. Methanogenesis probably does not contribute to the mineralization of carbohydrates at NaCl concentrations higher than 15%. Above this concentration, sulfate reduction is probably the main way to oxidize H2 (although at rates too low to use up all the H2 formed) and occupies a terminal function kn the degradation of carbohydrates. Three genera and five species of halophilic methylotrophic methanogens have been reported. A bloom of phototrophic bacteria in the marine salterns of Salins-de-Giraud, located on the

  3. Anaerobic bacteria from hypersaline environments.

    PubMed

    Ollivier, B; Caumette, P; Garcia, J L; Mah, R A

    1994-03-01

    Strictly anaerobic halophiles, namely fermentative, sulfate-reducing, homoacetogenic, phototrophic, and methanogenic bacteria are involved in the oxidation of organic carbon in hypersaline environments. To date, six anaerobic fermentative genera, containing nine species, have been described. Two of them are homoacetogens. Six species belong to the family Haloanaerobiaceae, as indicated by their unique 16S rRNA oligonucleotide sequences. Desulfohalobium retbaense and Desulfovibrio halophilus represent the only two moderately halophilic sulfate reducers so far reported. Among anoxygenic phototrophic anaerobes, a few purple bacteria with optimal growth at salinities between 6 and 11% NaCl have been isolated from hypersaline habitats. They belong to the genera Rhodospirillum, Chromatium, Thiocapsa, and Ectothiorhodospira. The commonest organisms isolated so far are Chromatium salexigens, Thiocapsa halophila, and Rhodospirillum salinarum. Extremely halophilic purple bacteria have most commonly been isolated from alkaline brines and require about 20 to 25% NaCl for optimal growth. They belong to the family Ectothiorodhospiraceae. Their osmoregulation involves synthesis or uptake of compatible solutes such as glycine-betaine that accumulate in their cytoplasm. The existence of methanogens in hypersaline environments is related to the presence of noncompetitive substrates such as methylamines, which originate mainly from the breakdown of osmoregulatory amines. Methanogenesis probably does not contribute to the mineralization of carbohydrates at NaCl concentrations higher than 15%. Above this concentration, sulfate reduction is probably the main way to oxidize H2 (although at rates too low to use up all the H2 formed) and occupies a terminal function kn the degradation of carbohydrates. Three genera and five species of halophilic methylotrophic methanogens have been reported. A bloom of phototrophic bacteria in the marine salterns of Salins-de-Giraud, located on the

  4. Combined treatment of olive mill wastewater by Fenton's reagent and anaerobic biological process.

    PubMed

    Amor, Carlos; Lucas, Marco S; García, Juan; Dominguez, Joaquín R; De Heredia, J Beltrán; Peres, José A

    2015-01-01

    This work presents the application of Fenton's reagent process combined with anaerobic digestion to treat an olive mill wastewater (OMW). Firstly, OMW was pre-treated by chemical oxidation in a batch reactor with Fenton's reagent, using a fixed H2O2/COD ratio of 0.20, pH = 3.5 and a H2O2/Fe(2+) molar ratio of 15:1. This advanced oxidation treatment allowed reaching reductions of 17.6 and 82.5% of chemical oxygen demand (COD) and total polyphenols (TP), respectively. Secondly, OMW treatment by anaerobic digestion was performed using previously adapted microorganisms immobilized in Sepiolite. These biological tests were carried out varying the substrate concentration supplied to the reactor and COD conversions from 52 to 74% were obtained. Afterwards, Fenton's reagent followed by anaerobic digestion was applied to OMW treatment. This combined process presented a significant improvement on organic load removal, reaching COD degradations from 64 to 88%. Beyond the pollutant load removal, it was also monitored the yield of methane generated throughout anaerobic experiments. The methane produced ranged from 281 cm(3) to 322 cm(3) of CH4/g COD removed. Additionally, a methane generation kinetic study was performed using the Monod Model. The application of this model allowed observing a kinetic constant increase of the combined process (kFN = 0.036 h(-1)) when compared to the single anaerobic process (kF = 0.017 h(-1)).

  5. 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.

  6. Anaerobic homolactate fermentation with Saccharomyces cerevisiae results in depletion of ATP and impaired metabolic activity.

    PubMed

    Abbott, Derek A; van den Brink, Joost; Minneboo, Inge M K; Pronk, Jack T; van Maris, Antonius J A

    2009-05-01

    Conversion of glucose to lactic acid is stoichiometrically equivalent to ethanol formation with respect to ATP formation from substrate-level phosphorylation, redox equivalents and product yield. However, anaerobic growth cannot be sustained in homolactate fermenting Saccharomyces cerevisiae. ATP-dependent export of the lactate anion and/or proton, resulting in net zero ATP formation, is suspected as the underlying cause. In an effort to understand the mechanisms behind the decreased lactic acid production rate in anaerobic homolactate cultures of S. cerevisiae, aerobic carbon-limited chemostats were performed and subjected to anaerobic perturbations in the presence of high glucose concentrations. Intracellular measurements of adenosine phosphates confirmed ATP depletion and decreased energy charge immediately upon anaerobicity. Unexpectedly, readily available sources of carbon and energy, trehalose and glycogen, were not activated in homolactate strains as they were in reference strains that produce ethanol. Finally, the anticipated increase in maximal velocity (V(max)) of glycolytic enzymes was not observed in homolactate fermentation suggesting the absence of protein synthesis that may be attributed to decreased energy availability. Essentially, anaerobic homolactate fermentation results in energy depletion, which, in turn, hinders protein synthesis, central carbon metabolism and subsequent energy generation.

  7. Degradation of furfural (2-furaldehyde) to methane and carbon dioxide by an anaerobic consortium

    SciTech Connect

    Rivard, C.J.; Grohmann, K.

    1991-12-31

    Furfural, a byproduct formed during the thermal/chemical pretreatment of hemicellulosic biomass, was degraded to methane and carbon dioxide under anaerobic conditions. The consortium of anaerobic microbes responsible for the degradation was enriched using small continuously stirred tank reactor (CSTR) systems with daily batch feeding of biomass pretreatment liquor and continuous addition of furfural. Although the continuous infusion of furfural was initially inhibitory to the anaerobic CSTR system, adaptation of the consortium occurred rapidly with high rates of furfural addition. Addition rates of 7.35 mg furfural/700-mL reactor/d resulted in biogas productions of 375%, of that produced in control CSTR systems, fed the biomass pretreatment liquor only. The anaerobic CSTR system fed high levels of furfural was stable, with a sludge pH of 7.1 and methane gas composition of 69%, compared to the control CSTR, which had a pH of 7.2 and 77% methane. CSTR systems in which furfural was continuously added resulted in 80% of the theoretically expected biogas. Intermediates in the anaerobic biodegradation of furfural were determined by spike additions in serum-bottle assays using the enriched consortium from the CSTR systems. Furfural was converted to several intermediates, including furfuryl alcohol, furoic acid, and acetic acid, before final conversion to methane and carbon dioxide.

  8. 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.

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

    SciTech Connect

    Rahayu, Suparni Setyowati; Purwanto, Budiyono

    2015-12-29

    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 CH{sub 4}/g COD and produce biogas containing of CH{sub 4}: 81.23% and CO{sub 2}: 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.

  10. Behavior of carbon monoxide as a trace component of anaerobic digester gases and methanogenesis from acetate

    SciTech Connect

    Hickey, R.F. ); Switzenbaum, M.S. )

    1990-11-01

    Carbon monoxide was a normal trace component of the gases produced during anaerobic sludge digestion. The CO concentration increased in response to perturbing the digestion process by increasing organic loading or adding acetate. Reducing the headspace methane level resulted in higher measured CO concentrations. Accordingly, a thermodynamic relationship was developed by dividing the acetoclastic methane reaction into two half-cell reactions, representing production of and subsequent oxidation of CO. A constant fraction of the total free energy available for acetate conversion to methane was assigned to each half-cell based on the basis of experimental observations. It was determined that approximately 54% of the energy available for acetate conversion to methane was consistently associated with the anaerobic oxidation of CO to carbon dioxide. Estimated values compared well for measured concentrations for both mesophilic and thermophilic digesters operating under steady-state conditions.

  11. Direct Conversion of Energy.

    ERIC Educational Resources Information Center

    Corliss, William R.

    This publication is one of a series of information booklets for the general public published by the United States Atomic Energy Commission. Direct energy conversion involves energy transformation without moving parts. The concepts of direct and dynamic energy conversion plus the laws governing energy conversion are investigated. Among the topics…

  12. Learning through Conversation.

    ERIC Educational Resources Information Center

    Kelly, Patricia R.; Klein, Adria F.; Pinnell, Gay Su

    1996-01-01

    Through teacher-child conversation, experts use oral language to help novices take on more complex tasks; and Reading Recovery children, who are obviously having difficulty with school-based learning, are especially in need of significant conversations with adults. Reading and writing processes are supported through conversation with Reading…

  13. Anaerobic Toxicity of Cationic Silver Nanoparticles

    EPA Pesticide Factsheets

    Toxicity data for the impact of nano-silver on anaerobic degradation.This dataset is associated with the following publication:Gitipour, A., S. Thiel, K. Scheckel, and T. Tolaymat. Anaerobic Toxicity of Cationic Silver Nanoparticles. D. Barcelo Culleres, and J. Gan SCIENCE OF THE TOTAL ENVIRONMENT. Elsevier BV, AMSTERDAM, NETHERLANDS, 557: 363-368, (2016).

  14. 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…

  15. 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...

  16. 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...

  17. 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...

  18. 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…

  19. 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…

  20. 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...

  1. 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...

  2. 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…

  3. Microbial dynamics during conversion from supragingival to subgingival biofilms in an in vitro model.

    PubMed

    Thurnheer, T; Bostanci, N; Belibasakis, G N

    2016-04-01

    The development of dental caries and periodontal diseases result from distinct shifts in the microbiota of the tooth-associated biofilm. This in vitro study aimed to investigate changes in biofilm composition and structure, during the shift from a 'supragingival' aerobic profile to a 'subgingival' anaerobic profile. Biofilms consisting of Actinomyces oris, Candida albicans, Fusobacterium nucleatum, Streptococcus oralis, Streptococcus mutans and Veillonella dispar were aerobically grown in saliva-containing medium on hydroxyapatite disks. After 64 h, Campylobacter rectus, Prevotella intermedia and Streptococcus anginosus were further added along with human serum, while culture conditions were shifted to microaerophilic. After 96 h, Porphyromonas gingivalis, Tannerella forsythia and Treponema denticola were finally added and the biofilm was grown anaerobically for another 64 h. At the end of each phase, biofilms were harvested for species-specific quantification and localization. Apart from C. albicans, all other species gradually increased during aerobic and microaerophilic conditions, but remained steady during anaerobic conditions. Biofilm thickness was doubled during the microaerophilic phase, but remained steady throughout the anaerobic phase. Extracellular polysaccharide presence was gradually reduced throughout the growth period. Biofilm viability was reduced during the microaerophilic conversion, but was recovered during the anaerobic phase. This in vitro study has characterized the dynamic structural shifts occurring in an oral biofilm model during the switch from aerobic to anaerobic conditions, potentially modeling the conversion of supragingival to subgingival biofilms. Within the limitations of this experimental model, the findings may provide novel insights into the ecology of oral biofilms.

  4. Anaerobic nitroxide-catalyzed oxidation of alcohols using the NO+/NO· redox pair.

    PubMed

    Holan, Martin; Jahn, Ullrich

    2014-01-03

    A new method for alcohol oxidation using TEMPO or AZADO in conjunction with BF3·OEt2 or LiBF4 as precatalysts and tert-butyl nitrite as a stoichiometric oxidant has been developed. The system is based on a NO(+)/NO· pair for nitroxide reoxidation under anaerobic conditions. This allows the simple, high-yielding conversion of various achiral and chiral alcohols to carbonyl compounds without epimerization and no formation of nonvolatile byproducts.

  5. Performance of converted pressure cookers and two conventional jars for anaerobic bacterial culture.

    PubMed

    Gargan, R A; Phillips, I

    1978-05-01

    The simple conversion of commercial pressure cookers into inexpensive anaerobic jars is described. These containers were shown to be as good as the small conventional BBL polycarbonate GasPak and large vented 150 gas-replacement jars when assessed by means of three biological indicators: Pseudomonas aeruginosa, Bacteroides melaninogenicus, and Bacteroides fragilis. Ps. aeruginosa seeded on Simmond's citrate agar was shown to be the most sensitive indicator of the three for traces of oxygen.

  6. Iterated multidimensional wave conversion

    SciTech Connect

    Brizard, A. J.; Tracy, E. R.; Johnston, D.; Kaufman, A. N.; Richardson, A. S.; Zobin, N.

    2011-12-23

    Mode conversion can occur repeatedly in a two-dimensional cavity (e.g., the poloidal cross section of an axisymmetric tokamak). We report on two novel concepts that allow for a complete and global visualization of the ray evolution under iterated conversions. First, iterated conversion is discussed in terms of ray-induced maps from the two-dimensional conversion surface to itself (which can be visualized in terms of three-dimensional rooms). Second, the two-dimensional conversion surface is shown to possess a symplectic structure derived from Dirac constraints associated with the two dispersion surfaces of the interacting waves.

  7. NGL data conversion system

    NASA Astrophysics Data System (ADS)

    Shoji, Masahiro; Horiuchi, Nobuyasu

    2005-06-01

    We are developing a NGL data conversion system for EPL, for LEEPL, and for EBDW, which is based on our established photomask data conversion system, PATACON PC-cluster. For EPL data conversion, it has SF division, Complementary division, Stitching, Proximity effect correction, Alignment mark insertion, EB stepper control data creation, and Mask inspection data creation. For LEEPL data conversion, it has Pattern checking, Complementary division, Stitching, Stress distortion correction, Alignment mark insertion, and Mask inspection data creation. For EB direct-writing data conversion, it has Proximity effect correction and Extraction of aperture pattern for cell projection exposure.

  8. Anaerobic acidogenesis of dairy manure

    SciTech Connect

    Krones, M.J.

    1989-01-01

    The objective of this research was to determine if high rate acidogenic fermentation of dairy manure was possible, Whole dairy manure was ground and diluted to 4% total solids and fed to a 10 L anaerobic chemostat operating at 35C and with hydraulic retention times varying between 6 and 50 hours. Several physical and organic parameters of the influent and effluent were measured and compared. The results indicated that the manure was too refractory for high rate liquefaction and hydrolysis. A second experiment was conducted using the same techniques and substrate but varying the substrate pH between 5 and 7. The objectives were to further investigate the pH sensitivity of the acidogenic process and to determine if, by introducing a substrate with a low pH, acidogenesis might proceed more efficiently. The primary result of decreasing the pH was a smaller proportion of methane and an increased proportion of hydrogen in the gas. Liquefaction and hydrolysis continued to be rate limiting and appeared to be a major impediment to two phase anaerobic treatment of dairy manure.

  9. Anaerobic digestion in rural China

    SciTech Connect

    Henderson, J.P.

    1997-01-01

    The People`s Republic of China has been promoting underground, individual, anaerobic digesters to process rural organic materials. This strategy has resulted in approximately five million household anaerobic digesters installed in China today. Simple reactors provide energy and fertilizer for Chinese farms and villages. Another benefit includes improved household sanitation. Reactor design has evolved over time. In the standard modern design, effluent is removed from the reactor at the top of the water column, meaning that supernatant is collected rather than sludge. Additionally, no mixing of the system occurs when effluent is removed. In some systems, a vertical cylindrical pull-rod port is added to the base of the effluent port. Effluent is removed by moving the pull-rod - simply a wooden shaft with a metal disk on the bottom - up and down in the port. A bucket can be placed directly under the pull-rod port, simplifying effluent removal, while the movement of the wooden shaft provides some mixing in the reactor. The gas primarily is used for cooking and lighting. A digester can provide approximately 60 percent of a family`s energy needs. Effluent from the reactors is an odorless, dark colored slurry, primarily used as an agricultural fertilizer. 3 figs.

  10. Toxicants inhibiting anaerobic digestion: a review.

    PubMed

    Chen, Jian Lin; Ortiz, Raphael; Steele, Terry W J; Stuckey, David C

    2014-12-01

    Anaerobic digestion is increasingly being used to treat wastes from many sources because of its manifold advantages over aerobic treatment, e.g. low sludge production and low energy requirements. However, anaerobic digestion is sensitive to toxicants, and a wide range of compounds can inhibit the process and cause upset or failure. Substantial research has been carried out over the years to identify specific inhibitors/toxicants, and their mechanism of toxicity in anaerobic digestion. In this review we present a detailed and critical summary of research on the inhibition of anaerobic processes by specific organic toxicants (e.g., chlorophenols, halogenated aliphatics and long chain fatty acids), inorganic toxicants (e.g., ammonia, sulfide and heavy metals) and in particular, nanomaterials, focusing on the mechanism of their inhibition/toxicity. A better understanding of the fundamental mechanisms behind inhibition/toxicity will enhance the wider application of anaerobic digestion.

  11. 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.

  12. Comparison of Microcosm Tests and a Field Demonstration of Cometabolic Air Sparging With Propane for the Bioremediation of Trichloroethylene and cis-Dichloroethylene

    NASA Astrophysics Data System (ADS)

    Timmins, B.; Dolan, M. E.; Tovannabootr, A.; Azizian, M.; Semprini, L.; Magar, V. S.; Leeson, A.

    2001-12-01

    Cometabolic air sparging (CAS) is an innovative form of conventional air sparging, and is designed to degrade or remove chlorinated aliphatic hydrocarbon compounds (CAHs) in groundwater and to potentially treat these contaminants in the vadose zone. A CAS demonstration was conducted at McClellan AFB, California, for removal of chloroethenes (TCE, cis-DCE) from groundwater using propane as the cometabolic substrate. In support of this field demonstration both groundwater and vadose zone microcosm studies were performed. The microcosms were created with groundwater and aquifer materials from the demonstration site. Concentrations of compounds in the microcosms were created to mimic conditions where the demonstration was performed. The microcosms were used to test the potential of the propane-utilizers to transform the CAHs of interest, and determine their nutrient requirements while transforming these compounds. Results from the first season of field-testing showed propane-utilizers could be effectively stimulated in the saturated zone with repeated intermediate sparging of propane and air. The lag time for effective propane utilization to be observed in the field was about 30 to 40 days, while in laboratory microcosms the lag period was about 12 days. Consistent with the field tests the groundwater microcosms showed cis-DCE was more rapidly transformed than TCE. Microcosm tests also indicated that propane inhibited the transformation of cis-DCE and TCE, and as observed in the field, most of the transformation of these compounds occurred after propane was reduced to low concentrations. In the field demonstration propane utilization rates and rates of CAH removal slowed after three to four months of repeated propane additions, which coincided with the depletion of nitrogen (as nitrate) in the treatment zone. Similar results were obtained with repeated additions of propane to the microcosms. In the field test ammonia was added to the propane/air mixture to provide a

  13. Cometabolism of Methyl tertiary Butyl Ether and Gaseous n-Alkanes by Pseudomonas mendocina KR-1 Grown on C5 to C8 n-Alkanes

    PubMed Central

    Smith, Christy A.; O'Reilly, Kirk T.; Hyman, Michael R.

    2003-01-01

    Pseudomonas mendocina KR-1 grew well on toluene, n-alkanes (C5 to C8), and 1° alcohols (C2 to C8) but not on other aromatics, gaseous n-alkanes (C1 to C4), isoalkanes (C4 to C6), 2° alcohols (C3 to C8), methyl tertiary butyl ether (MTBE), or tertiary butyl alcohol (TBA). Cells grown under carbon-limited conditions on n-alkanes in the presence of MTBE (42 μmol) oxidized up to 94% of the added MTBE to TBA. Less than 3% of the added MTBE was oxidized to TBA when cells were grown on either 1° alcohols, toluene, or dextrose in the presence of MTBE. Concentrated n-pentane-grown cells oxidized MTBE to TBA without a lag phase and without generating tertiary butyl formate (TBF) as an intermediate. Neither TBF nor TBA was consumed by n-pentane-grown cells, while formaldehyde, the expected C1 product of MTBE dealkylation, was rapidly consumed. Similar Ks values for MTBE were observed for cells grown on C5 to C8 n-alkanes (12.95 ± 2.04 mM), suggesting that the same enzyme oxidizes MTBE in cells grown on each n-alkane. All growth-supporting n-alkanes (C5 to C8) inhibited MTBE oxidation by resting n-pentane-grown cells. Propane (Ki = 53 μM) and n-butane (Ki = 16 μM) also inhibited MTBE oxidation, and both gases were also consumed by cells during growth on n-pentane. Cultures grown on C5 to C8 n-alkanes also exhibited up to twofold-higher levels of growth in the presence of propane or n-butane, whereas no growth stimulation was observed with methane, ethane, MTBE, TBA, or formaldehyde. The results are discussed in terms of their impacts on our understanding of MTBE biodegradation and cometabolism. PMID:14660389

  14. Characterization of the Initial Reactions during the Cometabolic Oxidation of Methyl tert-Butyl Ether by Propane-Grown Mycobacterium vaccae JOB5

    PubMed Central

    Smith, Christy A.; O'Reilly, Kirk T.; Hyman, Michael R.

    2003-01-01

    The initial reactions in the cometabolic oxidation of the gasoline oxygenate, methyl tert-butyl ether (MTBE), by Mycobacterium vaccae JOB5 have been characterized. Two products, tert-butyl formate (TBF) and tert-butyl alcohol (TBA), rapidly accumulated extracellularly when propane-grown cells were incubated with MTBE. Lower rates of TBF and TBA production from MTBE were also observed with cells grown on 1- or 2-propanol, while neither product was generated from MTBE by cells grown on casein-yeast extract-dextrose broth. Kinetic studies with propane-grown cells demonstrated that TBF is the dominant (≥80%) initial product of MTBE oxidation and that TBA accumulates from further biotic and abiotic hydrolysis of TBF. Our results suggest that the biotic hydrolysis of TBF is catalyzed by a heat-stable esterase with activity toward several other tert-butyl esters. Propane-grown cells also oxidized TBA, but no further oxidation products were detected. Like the oxidation of MTBE, TBA oxidation was fully inhibited by acetylene, an inactivator of short-chain alkane monooxygenase in M. vaccae JOB5. Oxidation of both MTBE and TBA was also inhibited by propane (Ki = 3.3 to 4.4 μM). Values for Ks of 1.36 and 1.18 mM and for Vmax of 24.4 and 10.4 nmol min−1 mg of protein−1 were derived for MTBE and TBA, respectively. We conclude that the initial steps in the pathway of MTBE oxidation by M. vaccae JOB5 involve two reactions catalyzed by the same monooxygenase (MTBE and TBA oxidation) that are temporally separated by an esterase-catalyzed hydrolysis of TBF to TBA. These results that suggest the initial reactions in MTBE oxidation by M. vaccae JOB5 are the same as those that we have previously characterized in gaseous alkane-utilizing fungi. PMID:12570997

  15. Analysis of carbon and nitrogen co-metabolism in yeast by ultrahigh-resolution mass spectrometry applying 13C- and 15N-labeled substrates simultaneously.

    PubMed

    Blank, Lars M; Desphande, Rahul R; Schmid, Andreas; Hayen, Heiko

    2012-06-01

    Alternative metabolic pathways inside a cell can be deduced using stable isotopically labeled substrates. One prerequisite is accurate measurement of the labeling pattern of targeted metabolites. Experiments are generally limited to the use of single-element isotopes, mainly (13)C. Here, we demonstrate the application of direct infusion nanospray, ultrahigh-resolution Fourier transform ion cyclotron resonance-mass spectrometry (FTICR-MS) for metabolic studies using differently labeled elemental isotopes simultaneously--i.e., (13)C and (15)N--in amino acids of a total protein hydrolysate. The optimized strategy for the analysis of metabolism by a hybrid linear ion trap-FTICR-MS comprises the collection of multiple adjacent selected ion monitoring scans. By limiting both the width of the mass range and the number of ions entering the ICR cell with automated gain control, sensitive measurements of isotopologue distribution were possible without compromising mass accuracy and isotope intensity mapping. The required mass-resolving power of more than 60,000 is only achievable on a routine basis by FTICR and Orbitrap mass spectrometers. Evaluation of the method was carried out by comparison of the experimental data to the natural isotope abundances of selected amino acids and by comparison to GC/MS results obtained from a labeling experiment with (13)C-labeled glucose. The developed method was used to shed light on the complexity of the yeast Saccharomyces cerevisiae carbon-nitrogen co-metabolism by administering both (13)C-labeled glucose and (15)N-labeled alanine. The results indicate that not only glutamate but also alanine acts as an amino donor during alanine and valine synthesis. Metabolic studies using FTICR-MS can exploit new possibilities by the use of multiple-labeled elemental isotopes.

  16. Effect of biomass feedstock chemical and physical properties on energy conversion processes: Volume 1, Overview

    SciTech Connect

    Butner, R.S.; Elliott, D.C.; Sealock, L.J. Jr.; Pyne, J.W.

    1988-12-01

    Pacific Northwest Laboratory has completed an initial investigation of the effects of physical and chemical properties of biomass feedstocks relative to their performance in biomass energy conversion systems. Both biochemical conversion routes (anaerobic digestion and ethanol fermentation) and thermochemical routes (combustion, pyrolysis, and gasification) were included in the study. Related processes including chemical and physical pretreatment to improve digestibility, and size and density modification processes such as milling and pelletizing were also examined. This overview report provides background and discussion of feedstock and conversion relationships, along with recommendations for future research. The recommendations include (1) coordinate production and conversion research programs; (2) quantify the relationship between feedstock properties and conversion priorities; (3) develop a common framework for evaluating and characterizing biomass feedstocks; (4) include conversion effects as part of the criteria for selecting feedstock breeding programs; and (5) continue emphasis on multiple feedstock/conversion options for biomass energy systems. 9 refs., 3 figs., 2 tabs.

  17. Effect of long term anaerobic and intermittent anaerobic/aerobic starvation on aerobic granules.

    PubMed

    Pijuan, Maite; Werner, Ursula; Yuan, Zhiguo

    2009-08-01

    The effect of long term anaerobic and intermittent anaerobic/aerobic starvation on the structure and activity of aerobic granules was studied. Aerobic granular sludge treating abattoir wastewater and achieving high levels of nutrient removal was subjected to 4-5 week starvation under anaerobic and intermittent anaerobic/aerobic conditions. Microscopic pictures of granules at the beginning of the starvation period presented a round and compact surface morphology with a much defined external perimeter. Under both starvation conditions, the morphology changed at the end of starvation with the external border of the granules surrounded by floppy materials. The loss of granular compactness was faster and more pronounced under anaerobic/aerobic starvation conditions. The release of Ca(2+) at the onset of anaerobic/aerobic starvation suggests a degradation of extracellular polymeric substances. The activity of ammonia oxidizing bacteria was reduced by 20 and 36% during anaerobic and intermittent anaerobic/aerobic starvation, respectively. When fresh wastewater was reintroduced, the granules recovered their initial morphology within 1 week of normal operation and the nutrient removal activity recovered fully in 3 weeks. The results show that both anaerobic and intermittent anaerobic/aerobic conditions are suitable for maintaining granule structure and activity during starvation.

  18. 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 NH4(+)-N in the better case were 100% and 98.3%, respectively.

  19. Anaerobic exercise in pediatric cystic fibrosis.

    PubMed

    Klijn, Peter H; Terheggen-Lagro, Suzanne W; Van Der Ent, Cornelis K; Van Der Net, Janjaap; Kimpen, Jan L; Helders, Paul J

    2003-09-01

    Anaerobic fitness is important for daily functioning of children with cystic fibrosis (CF). The aim of this study was to assess the determinants of anaerobic performance in CF. Anaerobic performance was measured in 39 children with CF (mean age, 13.2 +/- 1.8 (SD) years, forced expired volume in 1 sec (FEV(1)) 81.6 +/- 22.1% predicted), using a Wingate anaerobic test. Significant associations were found for peak power (PP) and mean power (MP) with fat-free mass (FFM) body weight, body mass index, maximal isometric muscle force, and aerobic capacity. Pulmonary function was correlated with anaerobic indices when controlled for FFM. Multiple regression analysis indicated that FFM and FEV(1) accounted for 82% and 86% of the variability in PP and MP, respectively. Patients with moderate CF (FEV(1) < 80%), as compared to mild CF (FEV(1) >/= 80%), had higher PP (difference = 85 W, 95% CI = 27-144 W) and MP (difference = 53 W, 95% CI = 42-63 W) at equivalent FFM. Our results indicate that FFM and pulmonary function are important determinants of anaerobic exercise performance in children with CF. With progression of pulmonary disease, anaerobic performance may be enhanced. Copyright 2003 Wiley-Liss, Inc.

  20. EFFECT OF MUSIC ON ANAEROBIC EXERCISE PERFORMANCE

    PubMed Central

    2013-01-01

    For years, mostly the effects of music on cardiorespiratory exercise performance have been studied, but a few studies have examined the effect of music on anaerobic exercise. The purpose of this study was to assess the effect of listening to music and its rhythm on anaerobic exercise: on power output, heart rate and the concentration of blood lactate. 28 male subjects were required to visit the laboratory on 6 occasions, each separated by 48 hours. Firstly, each subject performed the Running-based Anaerobic Sprint Test (RAST) under 3 conditions on separate days: while listening to “slow rhythm music”, “fast rhythm music” or “no music”. 48 hours after the subjects completed RAST under 3 conditions, Wingate Anaerobic Power (WAN) tests were performed under 3 music conditions. The order of the 3 conditions (slow music, fast music and no music) was selected randomly to prevent an order effect. Results showed no significant differences between 3 conditions in anaerobic power assessments, heart rate or blood lactate (p > 0.05). On the basis of these results it can be said that music cannot improve anaerobic performance. The type of music had no impact on power outputs during RAST and WAN exercise. As a conclusion, listening to music and its rhythm cannot enhance anaerobic performance and cannot change the physiological response to supramaximal exercise. PMID:24744463

  1. Molecular ecology of anaerobic reactor systems.

    PubMed

    Hofman-Bang, J; Zheng, D; Westermann, P; Ahring, B K; Raskin, L

    2003-01-01

    Anaerobic reactor systems are essential for the treatment of solid and liquid wastes and constitute a core facility in many waste treatment plants. Although much is known about the basic metabolism in different types of anaerobic reactors, little is known about the microbes responsible for these processes. Only a few percent of Bacteria and Archaea have so far been isolated, and almost nothing is known about the dynamics and interactions between these and other microorganisms. This lack of knowledge is most clearly exemplified by the sometimes unpredictable and unexplainable failures and malfunctions of anaerobic digesters occasionally experienced, leading to sub-optimal methane production and wastewater treatment. Using a variety of molecular techniques, we are able to determine which microorganisms are active, where they are active, and when they are active, but we still need to determine why and what they are doing. As genetic manipulations of anaerobes have been shown in only a few species permitting in-situ gene expression studies, the only way to elucidate the function of different microbes is to correlate the metabolic capabilities of isolated microbes in pure culture to the abundance of each microbe in anaerobic reactor systems by rRNA probing. This chapter focuses on various molecular techniques employed and problems encountered when elucidating the microbial ecology of anaerobic reactor systems. Methods such as quantitative dot blot/fluorescence in-situ probing using various specific nucleic acid probes are discussed and exemplified by studies of anaerobic granular sludge, biofilm and digester systems.

  2. Anaerobic filter for biogas production

    NASA Astrophysics Data System (ADS)

    Chavadej, S.

    1980-01-01

    A laboratory study evaluated the performance of an anaerobic filter in producing biogas from pig waste with 30,000 mg/l of COD. The filter packing was bamboo rings of 1 and 1/2 in. diameter, 1 in. long; the bamboo-bed filter operated satisfactorily in a wide COD loading range of 3.74-15.65 kg/cu m/d which corresponds to the hydraulic retention of 8.47 to 1.68 days. At the optimum loading of 7.299 kg COD/cu m/d, the largest gas rate of 0.212 cu m/kg of COD was produced. The required volume of the digester for 1.2 cu m/d of gas production would be only 1.5 cu m; in practical applications, consideration should be given to the gas collecting system and clogging problems.

  3. Anaerobic digestion of alcohol stillage

    SciTech Connect

    Binder, L.K.

    1981-01-01

    In the production of ethanol from grain, the distillation step produces a residue of distillers grains or stillage that contains greater than 90% water and is currently dried and used as a cattle feed supplement. Experimental work was carried out on the anaerobic digestion of the stillage to determine the feasibility of using the CH/sub 4/ produced to supply the energy required in the ethanol distillation step. The fermentation characteristics of the stillage were studied, and the amount of CH/sub 4/ produced was determined. Based on an economic analysis, the value of the pressed solids fraction of the stillage as feed is much greater than the potential return from producing CH/sub 4/.

  4. 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.

  5. 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.

  6. Anaerobic sequencing batch reactors and its influencing factors: an overview.

    PubMed

    Akil, K; Jayanthi, S

    2012-04-01

    Anaerobic sequencing batch reactors (ASBR) operate in four cyclic steps: feed, reaction, settling and discharge. ASBRs allow typical biological anaerobic metabolism from substrate consumption to methane and carbon dioxide production. Microorganisms in an ASBR are exposed to variable substrate concentrations over the duration of the cycle, resulting in high rates of substrate conversion and efficient biomass flocculation and settling. High substrate concentrations at the beginning of a cycle result in high metabolic activity and substrate removal. Low substrate concentrations towards the end of the cycle result in low biogas production and allow for good sludge settling. However, the cycles should be as frequent as possible while allowing for completion of each of the four stages. Operating by batches enables the solids residence time to be independent of the hydraulic retention time without recourse to a settling tank, since the reactor functions as a decanter whenever the stirring mechanism is turned off. This review presents an overview of the ASBR process and the various factors influencing its performance.

  7. Anaerobic Biodegradation of Pristane by Nitrate Reducing Bacteria

    NASA Astrophysics Data System (ADS)

    Dawson, K. S.; Freeman, K. H.; Macalady, J. L.

    2007-12-01

    In recent sediments, microbial biodegradation provides a control on the long-term preservation of organic matter, through the preferential loss of certain biomolecules and the alteration and concentration of other more recalcitrant molecules. Biodegradation of hydrocarbons derived from membrane lipids, has been demonstrated by both aerobic and strictly anaerobic culturing experiments. The isoprenoid pristane, once considered stable under anaerobic conditions, is in fact degraded by a denitrifying microcosm (BREGNARD et al., 1997) and a methanogenic, sulphate-reducing enrichment culture (GROSSI, 2000). We recently demonstrated pristane biodegradation and accompanying loss of nitrate by an activated sludge isolate. The measured nitrate consumption accounts for a 7.1 +/- 0.4 mg loss of pristane, 4.74% of the initial substrate, in 181 days, assuming pristane conversion to CO2. We have characterized the microorganisms active in the biodegradation process, through the creation of a 16S rDNA clone library, as well as fluorescence in situ hybridization (FISH). Experiments are in progress to enrich cultures of sulfate reducing bacteria that utilize pristane as a sole carbon source and to characterize reaction mechanisms in pristane-oxidizing pathways.

  8. 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.

  9. Gram-Positive Anaerobic Cocci

    PubMed Central

    Murdoch, D. A.

    1998-01-01

    Gram-positive anaerobic cocci (GPAC) are a heterogeneous group of organisms defined by their morphological appearance and their inability to grow in the presence of oxygen; most clinical isolates are identified to species in the genus Peptostreptococcus. GPAC are part of the normal flora of all mucocutaneous surfaces and are often isolated from infections such as deep organ abscesses, obstetric and gynecological sepsis, and intraoral infections. They have been little studied for several reasons, which include an inadequate classification, difficulties with laboratory identification, and the mixed nature of the infections from which they are usually isolated. Nucleic acid studies indicate that the classification is in need of radical revision at the genus level. Several species of Peptostreptococcus have recently been described, but others still await formal recognition. Identification has been based on carbohydrate fermentation tests, but most GPAC are asaccharolytic and use the products of protein degradation for their metabolism; the introduction of commercially available preformed enzyme kits affords a physiologically more appropriate method of identification, which is simple and relatively rapid and can be used in routine diagnostic laboratories. Recent reports have documented the isolation in pure culture of several species, notably Peptostreptococcus magnus, from serious infections. Studies of P. magnus have elucidated several virulence factors which correlate with the site of infection, and reveal some similarities to Staphylococcus aureus. P. micros is a strongly proteolytic species; it is increasingly recognized as an important pathogen in intraoral infections, particularly periodontitis, and mixed anaerobic deep-organ abscesses. Comparison of antibiotic susceptibility patterns reveals major differences between species. Penicillins are the antibiotics of choice, although some strains of P. anaerobius show broad-spectrum β-lactam resistance. PMID:9457430

  10. Sleep deprivation induced anxiety and anaerobic performance.

    PubMed

    Vardar, Selma Arzu; Oztürk, Levent; Kurt, Cem; Bulut, Erdogan; Sut, Necdet; Vardar, Erdal

    2007-01-01

    The aim of this study was to investigate the effects of sleep deprivation induced anxiety on anaerobic performance. Thirteen volunteer male physical education students completed the Turkish version of State Anxiety Inventory and performed Wingate anaerobic test for three times: (1) following a full-night of habitual sleep (baseline measurements), (2) following 30 hours of sleep deprivation, and (3) following partial-night sleep deprivation. Baseline measurements were performed the day before total sleep deprivation. Measurements following partial sleep deprivation were made 2 weeks later than total sleep deprivation measurements. State anxiety was measured prior to each Wingate test. The mean state anxiety following total sleep deprivation was higher than the baseline measurement (44.9 ± 12.9 vs. 27.6 ± 4.2, respectively, p = 0.02) whereas anaerobic performance parameters remained unchanged. Neither anaerobic parameters nor state anxiety levels were affected by one night partial sleep deprivation. Our results suggest that 30 hours continuous wakefulness may increase anxiety level without impairing anaerobic performance, whereas one night of partial sleep deprivation was ineffective on both state anxiety and anaerobic performance. Key pointsShort time total sleep deprivation (30 hours) increases state anxiety without any competition stress.Anaerobic performance parameters such as peak power, mean power and minimum power may not show a distinctive difference from anaerobic performance in a normal sleep day despite the high anxiety level induced by short time sleep deprivation.Partial sleep deprivation does not affect anxiety level and anaerobic performance of the next day.

  11. Degradation of methanethiol in a continuously operated upflow anaerobic sludge-blanket reactor.

    PubMed

    Sipma, Jan; van Bree, Robbie; Janssen, Albert J H; Arena, Blaise; Hulshoff, Pol Look W; Lettinga, Gatze

    2002-01-01

    The feasibility of anaerobic treatment of wastewater containing volatile organic sulfur compounds was investigated using biomass originating from an anaerobic wastewater treatment facility treating brewery wastewater. Interest focused mainly on the degradation of methanethiol (MT), an extremely volatile and malodorous sulfur compound. Formation of hydrogen sulfide from methanethiol, dimethyl sulfide (DMS), and dimethyl disulfide (DMDS) was observed. Batch experiments showed that methanethiol was predominantly used by methanogenic bacteria as the sole source of energy and carbon. Methane was formed on MT degradation, and in the presence of 2-bromoethanesulfonic acid (BES), a specific inhibitor of methanogens, MT conversion was strongly inhibited. During the MT degradation, DMS and DMDS were the other primary compounds found. Relatively small quantities of DMS were present; whereas the DMDS concentrations could accumulate as a result of the relatively fast rate at which methanethiol autoxidizes in the presence of minor amounts of molecular oxygen. It was shown that DMS and DMDS could be biologically degraded, resulting in the formation of methane and hydrogen sulfide. In a continuous experiment using a laboratory-scale upflow anaerobic sludge-blanket (UASB) reactor with a volume of 2.0 L, the feasibility of anaerobic treatment of methanethiol was tested. The reactor was operated at a hydraulic residence time (HRT) of 6 hours, temperature of 30 degrees C, and pH of 7.3 to 7.6. The maximal MT conversion efficiency in the continuous experiment was reached after approximately 70 days and exceeded 97% at an influent concentration of 6 mM, corresponding to a MT loading rate of 25 mM/d. The specific MT degradation rate, as determined after 40 days of operation in the UASB, measured 1.1 +/- 0.1 mM MT/g volatile suspended solids.d. These results show that anaerobic treatment of MT-containing waste streams is an interesting alternative for currently used physicochemical

  12. Conversing with Computers

    NASA Technical Reports Server (NTRS)

    2004-01-01

    I/NET, Inc., is making the dream of natural human-computer conversation a practical reality. Through a combination of advanced artificial intelligence research and practical software design, I/NET has taken the complexity out of developing advanced, natural language interfaces. Conversational capabilities like pronoun resolution, anaphora and ellipsis processing, and dialog management that were once available only in the laboratory can now be brought to any application with any speech recognition system using I/NET s conversational engine middleware.

  13. Energy from anaerobic methane production. [Sweden

    SciTech Connect

    Not Available

    1982-02-01

    Since 1970 Swedish researchers have been testing the ANAMET (anaerobic-aerobic-methane) process, which involves converting industrial wastewaters via an initial anaerobic microbiological step followed by an aerobic one. Recycling the biomass material in each step allows shorter hydraulic retention times without decreasing stability or solids reduction. Since the first ANAMET plants began operating at a Swedish sugar factory in 1972, 17 more plants have started up or are under construction. Moreover, the ANAMET process has engendered to offshoot BIOMET (biomass-methane) process, a thermophilic anaerobic scheme that can handle sugar-beet pulp as well as grass and other soft, fast-growing biomasses.

  14. 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.

  15. A Combined Activated Sludge Anaerobic Digestion Model (CASADM) to understand the role of anaerobic sludge recycling in wastewater treatment plant performance.

    PubMed

    Young, Michelle N; Marcus, Andrew K; Rittmann, Bruce E

    2013-05-01

    The Combined Activated Sludge-Anaerobic Digestion Model (CASADM) quantifies the effects of recycling anaerobic-digester (AD) sludge on the performance of a hybrid activated sludge (AS)-AD system. The model includes nitrification, denitrification, hydrolysis, fermentation, methanogenesis, and production/utilization of soluble microbial products and extracellular polymeric substances (EPS). A CASADM example shows that, while effluent COD and N are not changed much by hybrid operation, the hybrid system gives increased methane production in the AD and decreased sludge wasting, both caused mainly by a negative actual solids retention time in the hybrid AD. Increased retention of biomass and EPS allows for more hydrolysis and conversion to methane in the hybrid AD. However, fermenters and methanogens survive in the AS, allowing significant methane production in the settler and thickener of both systems, and AD sludge recycle makes methane formation greater in the hybrid system.

  16. Marine biomass program: anaerobic digestion systems development and stability study. Final report 1 Feb-31 Dec 82

    SciTech Connect

    Fannin, K.F.; Srivastava, V.J.; Mensinger, J.D.; Chynoweth, D.P.

    1983-07-01

    Marine biomass represents a significant potential worldwide energy resource that can be converted to methane by anaerobic digestion. Through efficient biomass production, harvesting, and conversion techniques, competitive methane gas costs are achievable. The objective of this research project is to develop and define an anaerobic digestion process for producing methane from giant brown kelp (Macrocystis pyrifera). Kelp continues to show superior performance as a feedstock for gas production when compared with other particulate biomass feedstocks. Further work on upflow solids reactors and two-phase reactor systems is expected to improve gas cost estimates over those made using other state-of-the-art reactors.

  17. Biogas production from anaerobic waste stabilisation ponds treating dairy and piggery wastewater in New Zealand.

    PubMed

    Park, J B K; Craggs, R J

    2007-01-01

    New Zealand has over 1000 anaerobic wastewater stabilisation ponds used for the treatment of wastewater from farms and industry. Traditional anaerobic ponds were not designed to optimise anaerobic digestion of wastewater biomass to produce biogas and these uncovered ponds allowed biogas to escape to the atmosphere. This release of biogas not only causes odour problems, but contributes to GHG (greenhouse gas) emissions and is wasteful of energy that could be captured and used. Biogas production from anaerobic stabilisation ponds treating piggery and dairy wastewater was measured using floating 25 m2 HDPE covers on the pond surface. Biogas composition was analysed monthly and gas production was continually monitored. Mean areal biogas (methane) production rates from piggery and dairy anaerobic ponds were 0.78 (0.53) m3/m2/d and 0.03 (0.023) m3/m2/d respectively. Average CH4 content of the piggery and dairy farm biogas were 72.0% and 80.3% respectively. Conversion of the average volume of methane gas that could be captured from the piggery and dairy farm ponds (393.4 m3/d and 40.7 m3/d) to electricity would reduce CO2 equivalent GHG emissions by 5.6 tonnes/d and 0.6 tonnes/d and generate 1,180 kWh/d and 122 kWh/d. These results suggest that anaerobic ponds in New Zealand release considerable amounts of GHG and that there is great potential for energy recovery.

  18. 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

  19. Conversation et Television (Conversation and Television)

    ERIC Educational Resources Information Center

    Vadde, Jean-Pierre

    1977-01-01

    Czechosovakian television has just presented a series of French Conversation Classes using audiovisual techniques and starring Czech actors and actresses. The setting of each dialog is in Czechoslovakia, and the situations are those in which a Czech would use French in his or her native land. (Text is in French.) (AMH)

  20. Anaerobic Mineralization of Toluene by Enriched Sediments with Quinones and Humus as Terminal Electron Acceptors

    PubMed Central

    Cervantes, Francisco J.; Dijksma, Wouter; Duong-Dac, Tuan; Ivanova, Anna; Lettinga, Gatze; Field, Jim A.

    2001-01-01

    The anaerobic microbial oxidation of toluene to CO2 coupled to humus respiration was demonstrated by use of enriched anaerobic sediments from the Amsterdam petroleum harbor (APH) and the Rhine River. Both highly purified soil humic acids (HPSHA) and the humic quinone moiety model compound anthraquinone-2,6-disulfonate (AQDS) were utilized as terminal electron acceptors. After 2 weeks of incubation, 50 and 85% of added uniformly labeled [13C]toluene were recovered as 13CO2 in HPSHA- and AQDS-supplemented APH sediment enrichment cultures, respectively; negligible recovery occurred in unsupplemented cultures. The conversion of [13C]toluene agreed with the high level of recovery of electrons as reduced humus or as anthrahydroquinone-2,6-disulfonate. APH sediment was also able to use nitrate and amorphous manganese dioxide as terminal electron acceptors to support the anaerobic biodegradation of toluene. The addition of substoichiometric amounts of humic acids to bioassay reaction mixtures containing amorphous ferric oxyhydroxide as a terminal electron acceptor led to more than 65% conversion of toluene (1 mM) after 11 weeks of incubation, a result which paralleled the partial recovery of electron equivalents as acid-extractable Fe(II). Negligible conversion of toluene and reduction of Fe(III) occurred in these bioassay reaction mixtures when humic acids were omitted. The present study provides clear quantitative evidence for the mineralization of an aromatic hydrocarbon by humus-respiring microorganisms. The results indicate that humic substances may significantly contribute to the intrinsic bioremediation of anaerobic sites contaminated with priority pollutants by serving as terminal electron acceptors. PMID:11571145

  1. Effect of chlorate, molybdate, and shikimic acid on Salmonella enterica serovar Typhimurium in aerobic and anaerobic cultures.

    PubMed

    Oliver, Christy E; Beier, Ross C; Hume, Michael E; Horrocks, Shane M; Casey, Thomas A; Caton, Joel S; Nisbet, David J; Smith, David J; Krueger, Nathan A; Anderson, Robin C

    2010-04-01

    Experiments were conducted to determine factors that affect sensitivity of Salmonella enterica serovar Typhimurium to sodium chlorate (5mM). In our first experiment, cultures grown without chlorate grew more rapidly than those with chlorate. An extended lag before logarithmic growth was observed in anaerobic but not aerobic cultures containing chlorate. Chlorate inhibition of growth during aerobic culture began later than that observed in anaerobic cultures but persisted once inhibition was apparent. Conversely, anaerobic cultures appeared to adapt to chlorate after approximately 10h of incubation, exhibiting rapid compensatory growth. In anaerobic chlorate-containing cultures, 20% of total viable counts were resistant to chlorate by 6h and had propagated to 100% resistance (>10(9)CFU mL(-1)) by 24h. In the aerobic chlorate-containing cultures, 12.9% of colonies had detectable resistance to chlorate by 6h, but only 1% retained detectable resistance at 24h, likely because these cultures had opportunity to respire on oxygen and were thus not enriched via the selective pressure of chlorate. In another study, treatment with shikimic acid (0.34 mM), molybdate (1mM) or their combination had little effect on aerobic or anaerobic growth of Salmonella in the absence of added chlorate. As observed in our earlier study, chlorate resistance was not detected in any cultures without added chlorate. Chlorate resistant Salmonella were recovered at equivalent numbers regardless of treatment after 8h of aerobic or anaerobic culture with added chlorate; however, by 24h incubation chlorate sensitivity was completely restored to aerobic but not anaerobic cultures treated with shikimic acid or molybdate but not their combination. Results indicate that anaerobic adaptation of S. Typhimurium to sodium chlorate during pure culture is likely due to the selective propagation of low numbers of cells exhibiting spontaneous resistance to chlorate and this resistance is not reversible by

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

    SciTech Connect

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

    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 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. 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.

  3. Characterization of anaerobic sulfite reduction by Salmonella typhimurium and purification of the anaerobically induced sulfite reductase

    SciTech Connect

    Hallenbeck, P.C. ); Clark, M.A.; Barrett, E.L. )

    1989-06-01

    Mutants of Salmonella typhimurium that lack the biosynthetic sulfite reductase (cysI and cysJ mutants) retain the ability to reduce sulfite for growth under anaerobic conditions. Here we report studies of sulfite reduction by a cysI mutant of S. typhimurium and purification of the associated anaerobic sulfite reductase. Sulfite reduction for anaerobic growth did not require a reducing atmosphere but was prevented by an argon atmosphere contaminated with air (<0.33%). It was also prevented by the presence of 0.1 mM nitrate. Anaerobic growth in liquid minimal medium, but not on agar, was found to require additions of trace amounts (10{sup {minus}7} M) of cysteine. Spontaneous mutants that grew under the argon contaminated with air also lost the requirement for 10{sup {minus}7}M cysteine for anaerobic growth in liquid. A role for sulfite reduction in anaerobic energy generation was contraindicated by the findings that sulfite reduction did not improve cell yields, and anaerobic sulfite reductase activity was greatest during the stationary phase of growth. Sulfite reductase was purified from the cytoplasmic fraction of the anaerobically grown cysI mutant and was purified 190-fold. The most effective donor in crude extracts was NADH. NADHP and methyl viologen were, respectively, 40 and 30% as effective as NADH. Oxygen reversibly inhibited the enzyme. The anaerobic sulfite reductase showed some resemblance to the biosynthetic sulfite reductase, but apparently it has a unique, as yet unidentified function.

  4. 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.

  5. 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.

  6. 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

  7. 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 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 quality

  8. The Energetics of Aerobic versus Anaerobic Respiration.

    ERIC Educational Resources Information Center

    Champion, Timothy D.; Schwenz, Richard W.

    1990-01-01

    Background information, laboratory procedures, and a discussion of the results of an experiment designed to investigate the difference in energy gained from the aerobic and anaerobic oxidation of glucose are presented. Sample experimental and calculated data are included. (CW)

  9. The Energetics of Aerobic versus Anaerobic Respiration.

    ERIC Educational Resources Information Center

    Champion, Timothy D.; Schwenz, Richard W.

    1990-01-01

    Background information, laboratory procedures, and a discussion of the results of an experiment designed to investigate the difference in energy gained from the aerobic and anaerobic oxidation of glucose are presented. Sample experimental and calculated data are included. (CW)

  10. HIV-associated anaerobes ferment TB risk.

    PubMed

    Philips, Jennifer A

    2017-05-10

    Short-chain fatty acids produced by anaerobic bacteria increase the risk of TB in HIV-infected, antiretroviral drug-treated people. Copyright © 2017, American Association for the Advancement of Science.

  11. Conversations in Child Care

    ERIC Educational Resources Information Center

    Bardige, Betty; Segal, Marilyn

    2004-01-01

    In this article, Bardige and Segal discuss how teachers can help a toddler's language and literacy development through conversation. They suggest an array of tactics, from asking young children open-ended, intellectually challenging questions to going beyond the here and now when carrying on a conversation. Research has shown that the practice of…

  12. Energy conversion alternatives study

    NASA Technical Reports Server (NTRS)

    Shure, L. T.

    1979-01-01

    Comparison of coal based energy systems is given. Study identifies and compares various advanced energy conversion systems using coal or coal derived fuels for baselaoad electric power generation. Energy Conversion Alternatives Study (ECAS) reports provede government, industry, and general public with technically consistent basis for comparison of system's options of interest for fossilfired electric-utility application.

  13. The Art of Conversation.

    ERIC Educational Resources Information Center

    Ervin-Tripp, Susan

    1984-01-01

    Criticizes Dorval and Eckerman (included in this issue) for their findings' lack of generality due to the artificial nature of the conversational groups studied. Also both age changes in the ability to plan large conversational units and the functions of particular kinds of turns within these larger units are left unexplored. (CB)

  14. Recording Conversations in Schools.

    ERIC Educational Resources Information Center

    Gluckman, Ivan B.; Koerner, Thomas J., Jr.

    1988-01-01

    In general, because of varying federal and state legislation and a paucity of court decisions, the law governing the recording of conversations is in considerable flux. School personnel desiring to record conversations in school without the consent or knowledge of all parties involved must proceed with considerable caution. (Author)

  15. Content for Conversation Partners.

    ERIC Educational Resources Information Center

    Olson, Kathleen

    2002-01-01

    Suggests that a good strategy for helping English language learners to develop communicative competence in English is by pairing them with native English speakers. In such conversation programs, conversation partners should be provided with topics and activities that incorporate the goals, interests, and experiences of the learners. Recommends…

  16. The Conversation Class

    ERIC Educational Resources Information Center

    Jackson, Acy L.

    2012-01-01

    The conversation class occupies a unique place in the process of learning English as a second or foreign language. From the author's own experience in conducting special conversation classes with Persian-speaking adults, he has drawn up a number of simple but important guidelines, some of which he hopes may provide helpful suggestions for the…

  17. NUCLEAR CONVERSION APPARATUS

    DOEpatents

    Seaborg, G.T.

    1960-09-13

    A nuclear conversion apparatus is described which comprises a body of neutron moderator, tubes extending therethrough, uranium in the tubes, a fluid- circulating system associated with the tubes, a thorium-containing fluid coolant in the system and tubes, and means for withdrawing the fluid from the system and replacing it in the system whereby thorium conversion products may be recovered.

  18. Anaerobic bioprocessing of low rank coals

    SciTech Connect

    Jain, M.K.; Narayan, R.; Han, O.

    1991-01-01

    significant achievements were: (1) Coal decarboxylation was achieved by batch bioreactor systems using adapted anaerobic microbial consortium. (2) Two new isolates with coal decarboxylation potential were obtained from adapted microbial consortia. (3) CHN and TG anaysis of anaerobically biotreated coals have shown an increase in the H/C ratio and evolution rate of volatile carbon which could be a better feedstock for the liquefaction process.

  19. 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.

  20. Anaerobic electron acceptor chemotaxis in Shewanella putrefaciens.

    PubMed

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

    1995-04-01

    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.

  1. Measurement of anaerobic work capacities in humans.

    PubMed

    Green, S

    1995-01-01

    The development of simple, noninvasive tests of work capacities, underpinned primarily by anaerobic metabolism, proliferated in the early 1970s. A 30-second maximal cycle test developed at the Wingate Institute initiated efforts to develop work tests of anaerobic capacities. Such tests can be developed using any ergometer which simulates competitive conditions and enables an accurate determination of mechanical work output. A 10-second all-out test is commonly used to measure maximal work output generated primarily via the hydrolysis of high-energy phosphagens (i.e. the alactic work capacity). In contrast, a variety of constant-load and all-out tests of anaerobic (alactic plus lactic) work capacity have been proposed. It has been suggested that all-out tests provide more information about physiological capabilities and are easier to apply than constant-load tests. The optimal duration for an all-out test of anaerobic work capacity is proposed at 30 seconds, a duration which may also provide the basis for the development of accurate field tests of anaerobic capacity. There is evidence that the y-intercept of the maximal work-derivation regression is a valid work estimate of anaerobic capacity in athletes, although its utility is undermined by the number of tests required for its derivation.

  2. Infected neonatal cephalohematomas caused by anaerobic bacteria.

    PubMed

    Brook, Itzhak

    2005-01-01

    To present the microbiological and clinical features of six children with infected cephalohematomas (IC) caused by anaerobic bacteria. Presentation of a case series. Polymicrobial infection was present in all instances, where the number of isolates varied from two to four. Two patients had anaerobes only and the other four had mixed flora of strict anaerobes and facultatives. There were 16 bacterial isolates (12 anaerobic, 4 aerobic). The anaerobic isolates were Peptostreptococcus spp. (5 isolates), Prevotella spp. (4), Bacteroides fragilis group (2), and Propionibacterium acnes (1). The aerobic isolates were E. coli (2), Staphylococcus aureus (1) and group B streptococci (1). Blood cultures were positive for three patients. The most common predisposing conditions were vacuum extraction and amnionitis (4 instances of each), instrumental delivery (3), electronic fetal monitoring (2), prolonged delivery (1), and premature rupture of membranes (1). All patients underwent drainage, and four also had surgical incision and drainage of the IC. Osteomyelitis developed in one instance and scalp abscess developed in two patients, both of whom had electronic fetal monitoring. All patients eventually recovered from infection after receiving parenteral and subsequent oral antibiotic therapy for a total of 14-38 days. This study highlights the polymicrobial nature and potential importance of anaerobic bacteria in IC in newborns.

  3. Physiological and functional diversity of phenol degraders isolated from phenol-grown aerobic granules: Phenol degradation kinetics and trichloroethylene co-metabolic activities.

    PubMed

    Zhang, Yi; Tay, Joo Hwa

    2016-03-15

    Aerobic granule is a novel form of microbial aggregate capable of degrading toxic and recalcitrant substances. Aerobic granules have been formed on phenol as the growth substrate, and used to co-metabolically degrade trichloroethylene (TCE), a synthetic solvent not supporting aerobic microbial growth. Granule formation process, rate limiting factors and the comprehensive toxic effects of phenol and TCE had been systematically studied. To further explore their potential at the level of microbial population and functions, phenol degraders were isolated and purified from mature granules in this study. Phenol and TCE degradation kinetics of 15 strains were determined, together with their TCE transformation capacities and other physiological characteristics. Isolation in the presence of phenol and TCE exerted stress on microbial populations, but the procedure was able to preserve their diversity. Wide variation was found with the isolates' kinetic behaviors, with the parameters often spanning 3 orders of magnitude. Haldane kinetics described phenol degradation well, and the isolates exhibited actual maximum phenol-dependent oxygen utilization rates of 9-449 mg DO g DW(-1) h(-1), in phenol concentration range of 4.8-406 mg L(-1). Both Michaelis-Menten and Haldane types were observed for TCE transformation, with the actual maximum rate of 1.04-21.1 mg TCE g DW(-1) h(-1) occurring between TCE concentrations of 0.42-4.90 mg L(-1). The TCE transformation capacities and growth yields on phenol ranged from 20-115 mg TCE g DW(-1) and 0.46-1.22 g DW g phenol(-1), respectively, resulting in TCE transformation yields of 10-70 mg TCE g phenol(-1). Contact angles of the isolates were between 34° and 82°, suggesting both hydrophobic and hydrophilic cell surface. The diversity in the isolates is a great advantage, as it enables granules to be versatile and adaptive under different operational conditions.

  4. Full-scale demonstration of in situ cometabolic biodegradation of trichloroethylene in groundwater 2. Comprehensive analysis of field data using reactive transport modeling

    NASA Astrophysics Data System (ADS)

    Gandhi, Rahul K.; Hopkins, Gary D.; Goltz, Mark N.; Gorelick, Steven M.; McCarty, Perry L.

    2002-04-01

    We present an analysis of an extensively monitored full-scale field demonstration of in situ treatment of trichloroethylene (TCE) contamination by aerobic cometabolic biodegradation. The demonstration was conducted at Edwards Air Force Base in southern California. There are two TCE-contaminated aquifers at the site, separated from one another by a clay aquitard. The treatment system consisted of two recirculating wells located 10 m apart. Each well was screened in both of the contaminated aquifers. Toluene, oxygen, and hydrogen peroxide were added to the water in both wells. At one well, water was pumped from the upper aquifer to the lower aquifer. In the other well, pumping was from the lower to the upper aquifer. This resulted in a ``conveyor belt'' flow system with recirculation between the two aquifers. The treatment system was successfully operated for a 410 day period. We explore how well a finite element reactive transport model can describe the key processes in an engineered field system. Our model simulates TCE, toluene, oxygen, hydrogen peroxide, and microbial growth/death. Simulated processes include advective-dispersive transport, biodegradation, the inhibitory effect of hydrogen peroxide on biomass growth, and oxygen degassing. Several parameter values were fixed to laboratory values or values from previous modeling studies. The remaining six parameter values were obtained by calibrating the model to 7213 TCE concentration data and 6997 dissolved oxygen concentration data collected during the demonstration using a simulation-regression procedure. In this complex flow field involving reactive transport, TCE and dissolved oxygen concentration histories are matched very well by the calibrated model. Both simulated and observed toluene concentrations display similar high-frequency oscillations due to pulsed toluene injection approximately one half hour during each 8 hour period. Simulation results indicate that over the course of the demonstration, 6.9 kg

  5. Metabolic engineering of a xylose-isomerase-expressing Saccharomyces cerevisiae strain for rapid anaerobic xylose fermentation.

    PubMed

    Kuyper, Marko; Hartog, Miranda M P; Toirkens, Maurice J; Almering, Marinka J H; Winkler, Aaron A; van Dijken, Johannes P; Pronk, Jack T

    2005-02-01

    After an extensive selection procedure, Saccharomyces cerevisiae strains that express the xylose isomerase gene from the fungus Piromyces sp. E2 can grow anaerobically on xylose with a mu(max) of 0.03 h(-1). In order to investigate whether reactions downstream of the isomerase control the rate of xylose consumption, we overexpressed structural genes for all enzymes involved in the conversion of xylulose to glycolytic intermediates, in a xylose-isomerase-expressing S. cerevisiae strain. The overexpressed enzymes were xylulokinase (EC 2.7.1.17), ribulose 5-phosphate isomerase (EC 5.3.1.6), ribulose 5-phosphate epimerase (EC 5.3.1.1), transketolase (EC 2.2.1.1) and transaldolase (EC 2.2.1.2). In addition, the GRE3 gene encoding aldose reductase was deleted to further minimise xylitol production. Surprisingly the resulting strain grew anaerobically on xylose in synthetic media with a mu(max) as high as 0.09 h(-1) without any non-defined mutagenesis or selection. During growth on xylose, xylulose formation was absent and xylitol production was negligible. The specific xylose consumption rate in anaerobic xylose cultures was 1.1 g xylose (g biomass)(-1) h(-1). Mixtures of glucose and xylose were sequentially but completely consumed by anaerobic batch cultures, with glucose as the preferred substrate.

  6. Anaerobic digestion of municipal, industrial, and livestock wastes for energy recovery and disposal

    SciTech Connect

    Sax, R.I.; Lusk, P.D.

    1995-11-01

    The degradation of carbonaceous organic material by anaerobic bacteria leads to the production of methane gas (biogas) at the theoretical stoichiometric conversion rate of 0.35-cubic meters of methane per kilogram of Chemical Oxygen Demand (COD) reasonably close proximity to the site of this digestion process. The untreated biogas generated from anaerobic digestion typically contains from 55% to 75% methane content, with the balance consisting mainly of carbon dioxide and a small, but important, amount of hydrogen sulfide. The untreated biogas is normally saturated with water vapor at the temperature of the digestion process which typically is in the mesophilic range 25 to 38 degrees Celsius. This overview paper describes the types of anaerobic technologies which are presently used for the digestion of various type of municipal, industrial and livestock manure wastes, summarizes the principal developments which have taken place in the field during the past several years, and discusses the energy recovery economics for each of the three usage applications. The paper stratifies the use of anaerobic digestion technology for the treatment of wastewaters from industry (an application which has increased dramatically during the past decade) by geographical region, by industry type, very various categories of food processing, and by technology type, in all cases taking account of system size to emphasize the economics of energy production.

  7. 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

  8. 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.

  9. Multi-step sequential batch two-phase anaerobic composting of food waste.

    PubMed

    Shin, H S; Han, S K; Song, Y C; Lee, C Y

    2001-03-01

    This study was conducted to evaluate the newly devised process, called MUlti-step Sequential batch Two-phase Anaerobic Composting (MUSTAC). The MUSTAC process consisted of several leaching beds for hydrolysis, acidification and post-treatment, and a UASB reactor for methane recovery. This process to treat food waste was developed with a high-rate anaerobic composting technique based on the rate-limiting step approach. Rumen microorganisms were inoculated to improve the low efficiency of acidogenic fermentation. Both two-phase anaerobic digestion and sequential batch operation were used to control environmental constraints in anaerobic degradation. The MUSTAC process demonstrated excellent performance as it resulted in a large reduction in volatile solids (VS) (84.7%) and high methane conversion efficiency (84.4%) at high organic loading rates (10.8 kg VS m(-3) d(-1)) in a short SRT (10 days). Methane yield was 0.27 m3 kg(-1) VS, while methane gas production rate was 2.27 m3 m(-3) d(-1). The output from the post-treatment could be used as a soil amendment, which was produced at the same acidogenic fermenter without troublesome moving. The main advantages of the MUSTAC process were simple operation and high efficiency. The MUSTAC process proved stable, reliable and effective in resource recovery as well as waste stabilization.

  10. Anaerobic waste-activated sludge digestion - A bioconversion mechanism and kinetic model

    SciTech Connect

    Shimizu, Tatsuo; Kudo, Kenzo; Nasu, Yoshikazu )

    1993-05-01

    The anaerobic bioconversion of raw and mechanically lysed waste-activated sludge was kinetically investigated. The hydrolysis of the biopolymers, such as protein, which leaked out from the biological sludge with ultrasonic lysis, was a first-order reaction in anaerobic digestion and the rate constant was much higher than the decay rate constant of the raw waste activated sludge. An anaerobic digestion model that is capable of evaluating the effect of the mechanical sludge lysis on digestive performance was developed. The present model includes four major biological processes - the release of intracellular matter with sludge lysis; hydrolysis of biopolymers to volatile acids; the degradation of various volatile acids to acetate; and the conversion of acetate and hydrogen to methane. Each process was assumed to follow first-order kinetics. The model approximately simulated the overall process performance of the anaerobic digestion of waste-activated sludge. The model suggested that when the lysed waste-activated sludge was fed, the overall digestive performance remarkably increased in the two-phase system consisting of an acid forming process and a methanogenic process, which ensured the symbiotic growth of acetogenic and methanogenic bacteria.

  11. 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.

  12. Reversible and irreversible emission of methanethiol and dimethyl disulfide from anaerobically stored broccoli.

    PubMed

    Tulio, Artemio Z; Yamanaka, Hiroyuki; Ueda, Yoshinori; Imahori, Yoshihiro; Chachin, Kazuo

    2003-11-05

    The reversible and irreversible emission of methanethiol (MT) and dimethyl disulfide (DMDS) from broccoli florets was demonstrated during anaerobic storage at 20 degrees C for up to 24 h. Reversible emission of MT and DMDS was feasible only in broccoli stored for between 0 and 12 h under entirely anaerobic condition. Beyond that, the emission was completely irreversible. This irreversible process was demonstrated through significant reductions in the chlorophyll fluorescence values and rate of carbon dioxide production and significant increase in the membrane permeability of induced broccoli tissues after exposure to air and incubation. Irreversible emission was also demonstrated through significant change in color from the characteristic bright green to olive green as well as the conversion of chlorophyll a to pheophytin a and chlorophyll a' contents of the induced florets after hot-water treatment. These findings suggest that the irreversible emission of MT and DMDS is a function of permanent membrane damage and loss of intracellular compartmentation in the broccoli tissues as a result of the anaerobic induction. The off-odor formation can still be reversed if the affected tissue is only temporarily impaired by anaerobic condition, thereby maintaining the quality of stored broccoli.

  13. Engineering of Saccharomyces cerevisiae for efficient anaerobic alcoholic fermentation of L-arabinose.

    PubMed

    Wisselink, H Wouter; Toirkens, Maurice J; del Rosario Franco Berriel, M; Winkler, Aaron A; van Dijken, Johannes P; Pronk, Jack T; van Maris, Antonius J A

    2007-08-01

    For cost-effective and efficient ethanol production from lignocellulosic fractions of plant biomass, the conversion of not only major constituents, such as glucose and xylose, but also less predominant sugars, such as l-arabinose, is required. Wild-type strains of Saccharomyces cerevisiae, the organism used in industrial ethanol production, cannot ferment xylose and arabinose. Although metabolic and evolutionary engineering has enabled the efficient alcoholic fermentation of xylose under anaerobic conditions, the conversion of l-arabinose into ethanol by engineered S. cerevisiae strains has previously been demonstrated only under oxygen-limited conditions. This study reports the first case of fast and efficient anaerobic alcoholic fermentation of l-arabinose by an engineered S. cerevisiae strain. This fermentation was achieved by combining the expression of the structural genes for the l-arabinose utilization pathway of Lactobacillus plantarum, the overexpression of the S. cerevisiae genes encoding the enzymes of the nonoxidative pentose phosphate pathway, and extensive evolutionary engineering. The resulting S. cerevisiae strain exhibited high rates of arabinose consumption (0.70 g h(-1) g [dry weight](-1)) and ethanol production (0.29 g h(-1) g [dry weight](-1)) and a high ethanol yield (0.43 g g(-1)) during anaerobic growth on l-arabinose as the sole carbon source. In addition, efficient ethanol production from sugar mixtures containing glucose and arabinose, which is crucial for application in industrial ethanol production, was achieved.

  14. 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.

  15. Engineering of Saccharomyces cerevisiae for Efficient Anaerobic Alcoholic Fermentation of l-Arabinose▿

    PubMed Central

    Wisselink, H. Wouter; Toirkens, Maurice J.; del Rosario Franco Berriel, M.; Winkler, Aaron A.; van Dijken, Johannes P.; Pronk, Jack T.; van Maris, Antonius J. A.

    2007-01-01

    For cost-effective and efficient ethanol production from lignocellulosic fractions of plant biomass, the conversion of not only major constituents, such as glucose and xylose, but also less predominant sugars, such as l-arabinose, is required. Wild-type strains of Saccharomyces cerevisiae, the organism used in industrial ethanol production, cannot ferment xylose and arabinose. Although metabolic and evolutionary engineering has enabled the efficient alcoholic fermentation of xylose under anaerobic conditions, the conversion of l-arabinose into ethanol by engineered S. cerevisiae strains has previously been demonstrated only under oxygen-limited conditions. This study reports the first case of fast and efficient anaerobic alcoholic fermentation of l-arabinose by an engineered S. cerevisiae strain. This fermentation was achieved by combining the expression of the structural genes for the l-arabinose utilization pathway of Lactobacillus plantarum, the overexpression of the S. cerevisiae genes encoding the enzymes of the nonoxidative pentose phosphate pathway, and extensive evolutionary engineering. The resulting S. cerevisiae strain exhibited high rates of arabinose consumption (0.70 g h−1 g [dry weight]−1) and ethanol production (0.29 g h−1 g [dry weight]−1) and a high ethanol yield (0.43 g g−1) during anaerobic growth on l-arabinose as the sole carbon source. In addition, efficient ethanol production from sugar mixtures containing glucose and arabinose, which is crucial for application in industrial ethanol production, was achieved. PMID:17545317

  16. 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.

  17. Postoperative conversion disorder.

    PubMed

    Afolabi, Kola; Ali, Sameer; Gahtan, Vivian; Gorji, Reza; Li, Fenghua; Nussmeier, Nancy A

    2016-05-01

    Conversion disorder is a psychiatric disorder in which psychological stress causes neurologic deficits. A 28-year-old female surgical patient had uneventful general anesthesia and emergence but developed conversion disorder 1 hour postoperatively. She reported difficulty speaking, right-hand numbness and weakness, and right-leg paralysis. Neurologic examination and imaging revealed no neuronal damage, herniation, hemorrhage, or stroke. The patient mentioned failing examinations the day before surgery and discontinuing her prescribed antidepressant medication, leading us to diagnose conversion disorder, with eventual confirmation by neuroimaging and follow-up examinations. Copyright © 2016 Elsevier Inc. All rights reserved.

  18. Solar Thermal Conversion

    SciTech Connect

    Kreith, F.; Meyer, R. T.

    1982-11-01

    The thermal conversion process of solar energy is based on well-known phenomena of heat transfer (Kreith 1976). In all thermal conversion processes, solar radiation is absorbed at the surface of a receiver, which contains or is in contact with flow passages through which a working fluid passes. As the receiver heats up, heat is transferred to the working fluid which may be air, water, oil, or a molten salt. The upper temperature that can be achieved in solar thermal conversion depends on the insolation, the degree to which the sunlight is concentrated, and the measures taken to reduce heat losses from the working fluid.

  19. 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.

  20. Responsive Teaching through Conversation

    ERIC Educational Resources Information Center

    Dozier, Cheryl; Garnett, Susan; Tabatabai, Simeen

    2011-01-01

    Conversations are the heart of responsive teaching. By talking with struggling learners, teachers can find out about their interests in order to design effective, personalized instruction; build relationships; work through complexities in teaching and learning; and celebrate successes.

  1. Photochemical Energy Conversion.

    ERIC Educational Resources Information Center

    Batschelet, William H.; George, Arnold

    1986-01-01

    Describes procedures for two demonstrations: (1) photochemical energy conversion using ferric oxalate actinometry and (2) liquification of gases using Freon 114. Safety precautions are given for both demonstrations, as are procedures and material specifications. (JM)

  2. Responsive Teaching through Conversation

    ERIC Educational Resources Information Center

    Dozier, Cheryl; Garnett, Susan; Tabatabai, Simeen

    2011-01-01

    Conversations are the heart of responsive teaching. By talking with struggling learners, teachers can find out about their interests in order to design effective, personalized instruction; build relationships; work through complexities in teaching and learning; and celebrate successes.

  3. Metabolic interactions between methanogenic consortia and anaerobic respiring bacteria.

    PubMed

    Stams, A J M; Oude Elferink, S J W H; Westermann, P

    2003-01-01

    Most types of anaerobic respiration are able to outcompete methanogenic consortia for common substrates if the respective electron acceptors are present in sufficient amounts. Furthermore, several products or intermediate compounds formed by anaerobic respiring bacteria are toxic to methanogenic consortia. Despite the potentially adverse effects, only few inorganic electron acceptors potentially utilizable for anaerobic respiration have been investigated with respect to negative interactions in anaerobic digesters. In this chapter we review competitive and inhibitory interactions between anaerobic respiring populations and methanogenic consortia in bioreactors. Due to the few studies in anaerobic digesters, many of our discussions are based upon studies of defined cultures or natural ecosystems.

  4. Structured luminescence conversion layer

    DOEpatents

    Berben, Dirk; Antoniadis, Homer; Jermann, Frank; Krummacher, Benjamin Claus; Von Malm, Norwin; Zachau, Martin

    2012-12-11

    An apparatus device such as a light source is disclosed which has an OLED device and a structured luminescence conversion layer deposited on the substrate or transparent electrode of said OLED device and on the exterior of said OLED device. The structured luminescence conversion layer contains regions such as color-changing and non-color-changing regions with particular shapes arranged in a particular pattern.

  5. Conversational flow promotes solidarity.

    PubMed

    Koudenburg, Namkje; Postmes, Tom; Gordijn, Ernestine H

    2013-01-01

    Social interaction is fundamental to the development of various aspects of "we-ness". Previous research has focused on the role the content of interaction plays in establishing feelings of unity, belongingness and shared reality (a cluster of variables referred to as solidarity here). The present paper is less concerned with content, but focuses on the form of social interaction. We propose that the degree to which conversations flow smoothly or not is, of itself, a cue to solidarity. We test this hypothesis in samples of unacquainted and acquainted dyads who communicate via headsets. Conversational flow is disrupted by introducing a delay in the auditory feedback (vs. no delay). Results of three studies show that smoothly coordinated conversations (compared with disrupted conversations and a control condition) increase feelings of belonging and perceptions of group entitativity, independently of conversation content. These effects are driven by the subjective experience of conversational flow. Our data suggest that this process occurs largely beyond individuals' control. We conclude that the form of social interaction is a powerful cue for inferring group solidarity. Implications for the impact of modern communication technology on developing a shared social identity are discussed.

  6. 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.

  7. Thermal Energy Interchange During Anaerobic Methane Fermentation of Waste Organic Substrates

    PubMed Central

    Pohland, F. G.

    1968-01-01

    An experimental calorimeter-type anaerobic fermentation system was developed to evaluate the extent of thermal energy interchange during anaerobic digestion of waste organic solids at 36 C. Results over a period of 184 days indicated that the energy released during conversion of the waste substrate was utilized primarily for the production of CH4 and that any excess released as heat during normal digestion was not sufficient to overcome heat losses from the system. The more exothermic response observed during retarded digestion was attributed to the accumulation of volatile acids and associated reduction in gas yields. After combustion of the CH4 produced during digestion, between 2,370 and 3,950 kcal per lb of volatile solids converted per day was available for heating the process and maintaining optimal temperature conditions. Images Fig. 1 PMID:5684202

  8. Integrated treatment of municipal sewage sludge by deep dewatering and anaerobic fermentation for biohydrogen production.

    PubMed

    Yu, Li; Yu, Yang; Jiang, Wentian; Wei, Huangzhao; Sun, Chenglin

    2015-02-01

    The increasing sludge generated in wastewater treatment plants poses a threat to the environment. Based on the traditional processes, sludge dewatered by usual methods was further dewatered by hydraulic compression and the filtrate released was treated by anaerobic fermentation. The difficulties in sludge dewatering were associated with the existence of sludge flocs or colloidal materials. A suitable CaO dosage of 125 mg/g dry sludge (DS) could further decrease the moisture content of sludge from 82.4 to 50.9 %. The filtrate from the dewatering procedure was a potential substrate for biohydrogen production. Adding zero-valent iron (ZVI) into the anaerobic system improved the biohydrogen yield by 20 %, and the COD removal rate was lifted by 10 % as well. Meanwhile, the sludge morphology and microbial community were altered. The novel method could greatly reduce the sludge volume and successfully treated filtrate along with the conversion of organics into biohydrogen.

  9. 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.

  10. WASTEWATER reclamation and methane production using water hyacinth and anaerobic digestion

    SciTech Connect

    Chynoweth, D.P.; DoLenc, D.A.; Reddy, K.R.; Schwegler, B.

    1983-06-01

    This paper describes the results of research in progress to evaluate the technical and economic feasibility of utilizing water hyacinth ponds for treatment of domestic wastewater and the utilization of anaerobic digestion for conversion of the hyacinth crop and primary sludge to methane. The system concept illustrated in Figure I employs water hyacinth ponds for secondary and tertiary treatment of effluent from primary treatment (which removes settleable solids). Primary effluent supernatant is passed through water hyacinth ponds which effect organic and nutrient reduction. Collected primary sludge and harvested hyacinth are added as a blend to the anaerobic digestion process where a portion of the organic matter is converted to methane and carbon dioxide. The methane is separated from the carbon dioxide and used as an energy product.

  11. ANAEROBIC BIOLOGICAL TREATMENT OF PRODUCED WATER

    SciTech Connect

    John R. Gallagher

    2001-07-31

    During the production of oil and gas, large amounts of water are brought to the surface and must be disposed of in an environmentally sensitive manner. This is an especially difficult problem in offshore production facilities where space is a major constraint. The chief regulatory criterion for produced water is oil and grease. Most facilities have little trouble meeting this criterion using conventional oil-water separation technologies. However, some operations have significant amounts of naphthenic acids in the water that behave as oil and grease but are not well removed by conventional technologies. Aerobic biological treatment of naphthenic acids in simulated-produced water has been demonstrated by others; however, the system was easily overloaded by the large amounts of low-molecular-weight organic acids often found in produced waters. The objective of this research was to determine the ability of an anaerobic biological system to treat these organic acids in a simulated produced water and to examine the potential for biodegradation of the naphthenic acids in the anaerobic environment. A small fixed-film anaerobic biological reactor was constructed and adapted to treat a simulated produced water. The bioreactor was tubular, with a low-density porous glass packing material. The inocula to the reactor was sediment from a produced-water holding pond from a municipal anaerobic digester and two salt-loving methanogenic bacteria. During start-up, the feed to the reactor contained glucose as well as typical produced-water components. When glucose was used, rapid gas production was observed. However, when glucose was eliminated and the major organic component was acetate, little gas was generated. Methane production from acetate may have been inhibited by the high salt concentrations, by sulfide, or because of the lack, despite seeding, of microbes capable of converting acetate to methane. Toluene, a minor component of the produced water (0.1 g/L) was removed in the

  12. Anaerobic protocol for assessing industrial waste treatability

    SciTech Connect

    Young, J.C.; Khandaker, N.R.

    1996-11-01

    Recent promulgation of strict standards for industrial waste pretreatment has greatly increased the number of wastewaters that are candidates for anaerobic treatment. The challenge with industrial wastes is to determine the potential for anaerobic biodegradation prior to investing large amounts of time and expense in design and field investigation. Various methods have been used to assess the treatability of industrial wastewaters, but the methodology has varied significantly. In response to the need for a consistent procedure for determining the treatability of different industrial wastewaters by anaerobic processes, Young developed an anaerobic treatability screening protocol. The purpose of this paper is to describe the protocol and to report a number of case studies in which the test protocol was used to determine the feasibility of using anaerobic processes for treating specific industrial wastes. Specific examples include food processing wastes, chemical production wastes, petroleum wastes, and landfill leachate. Treatability was based on assessment of the rate and extent of biodegradation, identification of the presence of toxic substances, and dilution effects.

  13. Spectrum and treatment of anaerobic infections.

    PubMed

    Brook, Itzhak

    2016-01-01

    Anaerobes are the most predominant components of the normal human skin and mucous membranes bacterial flora, and are a frequent cause of endogenous bacterial infections. Anaerobic infections can occur in all body locations: the central nervous system, oral cavity, head and neck, chest, abdomen, pelvis, skin, and soft tissues. Treatment of anaerobic infection is complicated by their slow growth in culture, by their polymicrobial nature and by their growing resistance to antimicrobials. Antimicrobial therapy is frequently the only form of therapy needed, whereas in others it is an important adjunct to drainage and surgery. Because anaerobes generally are isolated mixed with aerobes, the antimicrobial chosen should provide for adequate coverage of both. The most effective antimicrobials against anaerobes are: metronidazole, the carbapenems (imipenem, meropenem, doripenem, ertapenem), chloramphenicol, the combinations of a penicillin and a beta-lactamase inhibitors (ampicillin or ticarcillin plus clavulanate, amoxicillin plus sulbactam, piperacillin plus tazobactam), tigecycline, cefoxitin and clindamycin. Copyright © 2015 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

  14. 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...

  15. Nutrient removal and microbial granulation in an anaerobic process treating inorganic and organic nitrogenous wastewater.

    PubMed

    Ahn, Y H; Kim, H C

    2004-01-01

    The sustainable anaerobic nitrogen removal and microbial granulation were investigated by using a laboratory anaerobic granular sludge bed reactor, treating synthetic (inorganic and organic) wastewater and piggery waste. From inorganic synthetic wastewater, lithoautotrophic ammonium oxidation to nitrite/nitrate was observed by an addition of hydroxylamine. Also, the results revealed that the Anammox intermediates (particularly, hydrazine) contents in the substrate would be one of the important parameters for success of the anaerobic nitrogen removal process. The results from organic synthetic wastewater show that if the Anammox organism were not great enough in the startup of the process, denitritation and anaerobic ammonification would be a process prior to the Anammox reaction. The anaerobic ammonium removal from the piggery waste was performed successfully, probably due to the Anammox intermediates contained in the substrate. This reactor shows a complex performance including the Anammox reaction and HAP crystallization, as well as having partial denitritation occurring simultaneously. From the activity test, the maximum specific N conversion rate was 0.1 g NH4-N/g VSS/day (0.77 g T-N/g VSS/day), indicating that potential denitritation is quite high. The NO2-N/NH4-N ratio to Anammox is 1.17. The colour of the biomass treating the piggery waste changed from black to dark red. It was also observed that the red-colored granular sludge had a diameter of 1-2 mm. The settleability assessment of the granular sludge revealed that the granular sludge had a good settleability even though it was worse than that of seed granular sludge.

  16. Recovery of methane-rich gas from solid-feed anaerobic digestion of ipomoea (Ipomoea carnea).

    PubMed

    Sankar Ganesh, P; Sanjeevi, R; Gajalakshmi, S; Ramasamy, E V; Abbasi, S A

    2008-03-01

    Studies are presented on new types of anaerobic digesters in which chopped or dry crushed Ipomoea carnea was fed without any other pretreatment, in an attempt to develop commercially viable means of utilizing the otherwise very harmful plant. Two types of solid-feed anaerobic digesters (SFADs) were studied. The first type had a single vessel in which the bottom 35% portion was separated from the top portion by a perforated PVC disk. The weed was charged from the top and inoculated with anaerobically digested cowdung-water slurry. The fermentation of the weed in the reactor led to the formation of volatile fatty acids (VFAs) plus some biogas. The leachate, rich in the VFAs, was passed through the perforated PVC sheet and collected in the lower portion of the vessel. The other type of reactors had two vessels, the first one was fully charged with the weed and the second received the VFA leachate. With both types were attached upflow anaerobic filters (UAFs) which converted the leachate into combustible biogas consisting of approximately 70% methane. All SFADs developed very consistent performance in terms of biogas yield within 17 weeks of start. The two-compartment reactors yielded significantly more biogas than the single-compartment reactors of corresponding total volume, and the reactors with which anaerobic filters (AF) were attached yielded more biogas than the ones without AF. The best performing units generated 2.41m(3) of biogas per m(3) of digester volume, as compared to 0.1-0.2m(3) of biogas, m(-3)d(-1), obtainable with conventional digesters. This indicates the viability of this technology. The spent weed can be vermicomposted directly to obtain good soil-conditioner cum fertilizer; earthworm Eudrilus eugeniae produced 540mg vermicast per animal every day, achieving near total conversion of feed to vermicast in 20 days. The proposed systems, thus, makes it possible to accomplish total utilization of ipomoea.

  17. Identification of genes specifically required for the anaerobic metabolism of benzene in Geobacter metallireducens

    PubMed Central

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

    2014-01-01

    Although the biochemical pathways for the anaerobic degradation of many of the hydrocarbon constituents in petroleum reservoirs have been elucidated, the mechanisms for anaerobic activation of benzene, a very stable molecule, are not known. Previous studies have demonstrated that Geobacter metallireducens can anaerobically oxidize benzene to carbon dioxide with Fe(III) as the sole electron acceptor and that phenol is an intermediate in benzene oxidation. In an attempt to identify enzymes that might be involved in the conversion of benzene to phenol, whole-genome gene transcript abundance was compared in cells metabolizing benzene and cells metabolizing phenol. Eleven genes had significantly higher transcript abundance in benzene-metabolizing cells. Five of these genes had annotations suggesting that they did not encode proteins that could be involved in benzene metabolism and were not further studied. Strains were constructed in which one of the remaining six genes was deleted. The strain in which the monocistronic gene Gmet 0232 was deleted metabolized phenol, but not benzene. Transcript abundance of the adjacent monocistronic gene, Gmet 0231, predicted to encode a zinc-containing oxidoreductase, was elevated in cells metabolizing benzene, although not at a statistically significant level. However, deleting Gmet 0231 also yielded a strain that could metabolize phenol, but not benzene. Although homologs of Gmet 0231 and Gmet 0232 are found in microorganisms not known to anaerobically metabolize benzene, the adjacent localization of these genes is unique to G. metallireducens. The discovery of genes that are specifically required for the metabolism of benzene, but not phenol in G. metallireducens is an important step in potentially identifying the mechanisms for anaerobic benzene activation. PMID:24904558

  18. 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.

  19. Anaerobic Degradation of the Benzene Nucleus by a Facultatively Anaerobic Microorganism1

    PubMed Central

    Taylor, Barrie F.; Campbell, William L.; Chinoy, Ira

    1970-01-01

    A bacterium was isolated by elective culture with p-hydroxybenzoate as substrate and nitrate as electron acceptor. It grew either aerobically or anaerobically, by nitrate respiration, on a range of aromatic compounds. The organism was identified as a pseudomonad and was given the trivial name Pseudomonas PN-1. Benzoate and p-hydroxybenzoate were metabolized aerobically via protocatechuate, followed by meta cleavage catalyzed by protocatechuic acid-4,5-oxygenase, to yield α-hydroxy-γ-carboxymuconic semialdehyde. Pseudomonas PN-1 grew rapidly on p-hydroxybenzoate under strictly anaerobic conditions, provided nitrate was present, even though protocatechuic acid-4,5-oxygenase was repressed. Suspensions of cells grown anaerobically on p-hydroxybenzoate oxidized benzoate with nitrate and produced 4 to 5 μmoles of CO2 per μmole of benzoate added; these cells did not oxidize benzoate aerobically. The patterns of the oxidation of aromatic substrates with oxygen or nitrate by cells grown aerobically or anaerobically on different aromatic compounds indicated that benzoate rather than protocatechuate was a key intermediate in the early stages of anaerobic metabolism. It was concluded that the pathway for the anaerobic breakdown of the aromatic ring is different and quite distinct from the aerobic pathway. Mechanisms for the anaerobic degradation of the benzene nucleus by Pseudomonas PN-1 are discussed. PMID:5419260

  20. 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.

  1. Physiologically anaerobic microorganisms of the deep subsurface

    SciTech Connect

    Stevens, S.E. Jr.; Chung, K.T.

    1992-06-01

    A variety of different media were used to isolate facultatively (FAB) and obligately anaerobic bacteria (OAB). These bacteria were isolated from core subsamples obtained from boreholes at the Idaho National Engineering Lab. (INEL) or at the Hanford Lab. (Yakima). Core material was sampled at various depths to 600 feet below the surface. All core samples with culturable bacteria contained at least FAB making thisthe most common physiological type of anaerobic bacteria present in the deep subsurface at these two sites. INEL core samples are characterized by isolates of both FAB and OAB. No isolates of acetogenic, methanogenic, or sulfate reducing bacteria were obtained. Yakima core samples are characterized by a marked predominance of FAB in comparison to OAB. In addition, isolates of acetogenic, methanogenic, and sulfate reducing bacteria were obtained. The Yakima site has the potential for complete anaerobic mineralization of organic compounds whereas this potential appears to be lacking at INEL.

  2. Biochemistry and physiology of anaerobic bacteria

    SciTech Connect

    2000-05-18

    We welcome you to The Power of Anaerobes. This conference serves two purposes. One is to celebrate the life of Harry D. Peck, Jr.,who was born May 18, 1927 and would have celebrated his 73rd birthday at this conference. He died November 20, 1998. The second is to gather investigators to exchange views within the realm of anaerobic microbiology, an area in which tremendous progress has been seen during recent years. It is sufficient to mention discoveries of a new form of life (the archaea), hyper or extreme thermophiles, thermophilic alkaliphiles and anaerobic fungi. With these discoveries has come a new realization about physiological and metabolic properties of microorganisms, and this in turn has demonstrated their importance for the development, maintenance and sustenance of life on Earth.

  3. Use of biochars in anaerobic digestion.

    PubMed

    Mumme, Jan; Srocke, Franziska; Heeg, Kathrin; Werner, Maja

    2014-07-01

    This study investigated the behavior of biochars from pyrolysis (pyrochar) and hydrothermal carbonization (hydrochar) in anaerobic digestion regarding their degradability and their effects on biogas production and ammonia inhibition. A batch fermentation experiment (42°C, 63 days) was conducted in 100mL syringes filled with 30 g inoculum, 2g biochar and four levels of total ammonium nitrogen (TAN). For pyrochar, no clear effect on biogas production was observed, whereas hydrochar increased the methane yield by 32%. This correlates with the hydrochar's larger fraction of anaerobically degradable carbon (10.4% of total carbon, pyrochar: 0.6%). Kinetic and microbiota analyses revealed that pyrochar can prevent mild ammonia inhibition (2.1 g TANk g(-1)). Stronger inhibitions (3.1-6.6 g TAN kg(-1)) were not mitigated, neither by pyrochar nor by hydrochar. Future research should pay attention to biochar-microbe interactions and the effects in continuously-fed anaerobic digesters.

  4. Anaerobes: a new aetiology in cavitary pneumoconiosis.

    PubMed Central

    del Campo, J M; Hitado, J; Gea, G; Colmeiro, A; Lanza, A M; Muñoz, J A; Mosquera, J A

    1982-01-01

    The role of mycobacteria in the cavitation of large pneumoconiotic masses is well established. In other cases softness is attributed to an ischaemic or aseptic necrosis. Five cases are described in which cavitation of the pulmonary masses was caused by anaerobic bacteria, confirmed by the growth of such bacterial in cultures after transtracheal or transpleural puncture. Repeated cultures for mycobacteria gave negative results. Two cases were acute, having serious complications such as bronchopleural fistula, empyema, and serious respiratory insufficiency. The role of anaerobes in cavitary pneumoconiosis has not been recognised previously, probably because of the special conditions required to culture these bacteria and the infrequent use of transtracheal puncture in the diagnosis of this entity. The prevalence of anaerobes as agents capable of cavitating pneumoconiotic masses remains to be established. Images PMID:6128024

  5. Anaerobic lipid degradation through acidification and methanization.

    PubMed

    Kim, Ijung; Kim, Sang-Hyoun; Shin, Hang-Sik; Jung, Jin-Young

    2010-01-01

    In biological wastewater treatment high lipid concentration is known to inhibit microorganisms and cause active biomass flotation. To reduce lipid inhibition, a two-phase anaerobic system, consisting of an anaerobic sequencing batch reactor (ASBR) and an upflow anaerobic sludge blanket (UASB) reactor, was applied to synthetic dairy wastewater. During 153 days of operation, the two-phase system showed stable performance in lipid degradation. In the ASBR, a 13% lipid removal efficiency and 10% double bond removal efficiency were maintained. In the UASB, the chemical oxygen demand (COD), lipid and volatile fatty acid (VFA) removal efficiencies were more than 80%, 70% and 95%, respectively, up to organic loading rate 6.5 g COD/L/day. There were no operational problems such as serious scum formation or sludge washout. Protein degradation occurred prior to degradation during acidogenesis.

  6. Improving Project Outcomes and Growing the Anaerobic Digestion Industy Report

    EPA Pesticide Factsheets

    Anaerobic digestion ombudsmen assist with project development, ensure the long-term sustainability of projects, and help advance the industry. This report explores the benefits of anaerobic digestion ombudsmen and provides guidance for implementing them.

  7. 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,...

  8. 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,...

  9. Clients as conversational agents.

    PubMed

    Massfeller, Helen F; Strong, Tom

    2012-08-01

    Conversational agency is our invented term that orients us to ways in which clients participate in therapeutic dialogues. In this study we examined how clients' conversational correctives and initiatives influenced collaborative therapeutic consultations. Thirty-five single-session lifestyle consultations were videotaped in which adult clients volunteered to discuss concerns of non-clinical severity with a counselor. We discursively microanalyzed excerpts where clients initiated topic shifts or corrected counselor misunderstandings and how counselors responded to them. Clients were actively involved in co-managing conversational developments during the consultations. They influenced the content and course of the conversations with the counselors by correcting, interrupting, or speaking from positions contrary or unrelated to those of the counselors. Clients observably influenced the conversational agenda through their correctives and initiatives if counselors were responsive during face-to-face consultations. Clinicians should demonstrate increased sensitivity and relational responsivity by intentionally engaging with clients' agentive contributions to consultative dialogues. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  10. Isomolybdate conversion coatings

    NASA Technical Reports Server (NTRS)

    Minevski, Zoran (Inventor); Maxey, Jason (Inventor); Nelson, Carl (Inventor); Eylem, Cahit (Inventor)

    2002-01-01

    A conversion coating solution and process forms a stable and corrosion-resistant layer on metal substrates or layers or, more preferably, on a boehmite layer or other base conversion coating. The conversion coating process involves contacting the substrate, layer or coating with an aqueous alkali metal isomolybdate solution in order to convert the surface of the substrate, layer or coating to a stable conversion coating. The aqueous alkali metal molybdates are selected from sodium molybdate (Na.sub.2 MoO.sub.4), lithium molybdate (Li.sub.2 MoO.sub.4), potassium molybdate (K.sub.2 MoO.sub.4), or combinations thereof, with the most preferred alkali metal molybdate being sodium molybdate. The concentration of alkali metal molybdates in the solution is preferably less than 5% by weight. In addition to the alkali metal molybdates, the conversion coating solution may include alkaline metal passivators selected from lithium nitrate (LiNO.sub.3), sodium nitrate (NaNO.sub.3), ammonia nitrate (NH.sub.4 NO.sub.3), and combinations thereof; lithium chloride, potassium hexafluorozirconate (K.sub.2 ZrF.sub.6) or potassium hexafluorotitanate (K.sub.2 TiF.sub.6).

  11. Laser energy conversion

    NASA Technical Reports Server (NTRS)

    Jalufka, N. W.

    1989-01-01

    The conversion of laser energy to other, more useful, forms is an important element of any space power transmission system employing lasers. In general the user, at the receiving sight, will require the energy in a form other than laser radiation. In particular, conversion to rocket power and electricity are considered to be two major areas where one must consider various conversion techniques. Three systems (photovoltaic cells, MHD generators, and gas turbines) have been identified as the laser-to-electricity conversion systems that appear to meet most of the criteria for a space-based system. The laser thruster also shows considerable promise as a space propulsion system. At this time one cannot predict which of the three laser-to-electric converters will be best suited to particular mission needs. All three systems have some particular advantages, as well as disadvantages. It would be prudent to continue research on all three systems, as well as the laser rocket thruster. Research on novel energy conversion systems, such as the optical rectenna and the reverse free-electron laser, should continue due to their potential for high payoff.

  12. Laser energy conversion

    NASA Astrophysics Data System (ADS)

    Jalufka, N. W.

    1989-07-01

    The conversion of laser energy to other, more useful, forms is an important element of any space power transmission system employing lasers. In general the user, at the receiving sight, will require the energy in a form other than laser radiation. In particular, conversion to rocket power and electricity are considered to be two major areas where one must consider various conversion techniques. Three systems (photovoltaic cells, MHD generators, and gas turbines) have been identified as the laser-to-electricity conversion systems that appear to meet most of the criteria for a space-based system. The laser thruster also shows considerable promise as a space propulsion system. At this time one cannot predict which of the three laser-to-electric converters will be best suited to particular mission needs. All three systems have some particular advantages, as well as disadvantages. It would be prudent to continue research on all three systems, as well as the laser rocket thruster. Research on novel energy conversion systems, such as the optical rectenna and the reverse free-electron laser, should continue due to their potential for high payoff.

  13. Sequential degradation of chlorophenols in anaerobic freshwater sediments

    SciTech Connect

    Zhang, X.

    1993-01-01

    Anaerobic degradation of 2,4-dichlorophenol and 3-chloro-4-hydroxybenzoate in the freshwater sediment samples was investigated. Studies of the enrichment cultures and a pure culture, adaptation times, correlation of substrate degradation and product accumulation, maximal observed transformation rates, temperature and pH ranges for the transformation provided the bases for the proposed sequential pathway for degradation of 2,4-dichlorophenol. At least six different bacterial species were required to catalyze following reactions: (1) the dechlorination of 2,4-dichlorophenol; (2) the dechlorination of 4-chlorophenol; (3) the para-carboxylation of phenol; (4) the reductive dehydroxylation of para-hydroxybenzoate; (5) the degradation of benzoate to acetate, H[sub 2] and CO[sub 2]; and (6) the conversion of H[sub 2]/CO[sub 2] and acetate to methane. The rate limiting reaction in the pathway was the dechlorination of 4-chlorophenol. A new species, Clostridium [open quote]hydroxybenzoicum[close quote], isolated from the enrichment, catalyzed the carboxylation of phenol at the para-position to 4-hydroxybenzoate by a reversible decarboxylation/carboxylation enzyme. 3,4-Dihydroxybenzoate was decarboxylated by a second enzyme in this organism. The activities were biotin and ATP independent. The bacterium, in a pure culture, did not benefit from the decarboxylation reaction but apparently it benefited in the phenol-degrading enrichment culture. Of 46 strains (42 species) tested, only three exhibited hydroxybenzoate decarboxylation activities:Clostridium thermoaceticum, Clostridium thermoautotrophicum,Clostridium scatologenes. The history of the sediment determined the first step in the anaerobic degradation.

  14. Anaerobic mixed-culture fermentation of aqueous ammonia-treated sugarcane bagasse in consolidated bioprocessing.

    PubMed

    Fu, Zhihong; Holtzapple, Mark T

    2010-06-01

    The MixAlco process is an example of consolidated bioprocessing (CBP) in which anaerobic mixed-culture fermentation biochemically converts any biodegradable feedstock into carboxylate salts. Downstream processing thermochemically transforms the resulting salts into mixed alcohol fuels or gasoline. To enhance digestibility, sugarcane bagasse was treated under mild conditions (55 degrees C, 24 h, and 30% aqueous ammonia solution with a loading of 10 mL/g dry biomass). Using NH(4)HCO(3) buffer, the feedstock (80% ammonia-treated sugarcane bagasse/20% chicken manure) was anaerobically fermented by a mixed culture of marine microorganisms at 55 degrees C. Four-stage countercurrent fermentations were performed at various volatile solids loading rates (VSLRs) and liquid residence times (LRTs). The highest acid productivity (1.14 g/(L day)) occurred at a total acid concentration of 29.8 g/L. The highest conversion (65%) occurred at a total acid concentration of 27.6 g/L. The continuum particle distribution model (CPDM) predicted the experimental total acid concentrations and conversions within 4.98% and 10.41%, respectively. When using NH(4)HCO(3) buffer, ammonia pretreatment is an attractive option. The CPDM "map" shows that both high volatile solid conversions (78.8%) and high acid concentrations (32.6 g/L) are possible with 300 g/(L liquid) substrate concentration, 30 days LRT, 2 g/(L day) solid loading rate and NH(4)HCO(3) buffer.

  15. Molecular and stable isotope methods to detect and measure anaerobic ammonium oxidation (anammox) in aquatic ecosystems.

    PubMed

    Song, Bongkeun; Tobias, Craig R

    2011-01-01

    Numerous microbial processes transform nitrogen (N) but three anaerobic respiratory pathways remove fixed N from the environment: denitrification (nitrate conversion to N(2)), anaerobic ammonium oxidation (anammox; ammonium plus nitrite conversion to N(2)), and nitrite dependent methane oxidation (nitrite conversion to N(2)). Nitrification becomes a part of N removal processes as a supplier of nitrite (NO(2)(-)) and nitrate (NO(3)(-)) to anammox and denitrifying bacteria in anoxic water and sediments. It is important to detect and measure anammox and denitrification to understand biogeochemical N cycle and to estimate N removal potential in aquatic ecosystems. Denitrification has been extensively studied in many ecosystems to examine diversity and spatial and temporal dynamics of denitrifying communities as well as to understand its importance in regional and global N cycles. Nitrite dependent methane oxidation was recently discovered as a new pathway of removing fixed N and just started to examine its importance in different ecosystems. Anammox has undergone limited examination, although the number of studies is continuously increasing. There are many questions remaining in order to understand the factors controlling activities and community structures of anammox bacteria in different ecosystems. This chapter reviews both molecular and stable isotope methods to detect and measure anammox in anoxic sediments and water. Copyright © 2011 Elsevier Inc. All rights reserved.

  16. 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.

  17. Robust regulation of anaerobic digestion processes.

    PubMed

    Mailleret, L; Bernard, O; Steyer, J P

    2003-01-01

    This paper deals with the problem of controlling anaerobic digestion processes. A two-step (i.e. acidogenesis-methanization) mass balance model is considered for a 1 m3 fixed bed digester treating industrial wine distillery wastewater. The control law aims at regulating the organic pollution level while avoiding washout of biomass. To this end, a simple output feedback controller is considered which regulates a variable strongly related to the Chemical Oxygen Demand (COD). Numerical simulations assuming noisy measurements first illustrate the robustness of this control procedure. Then, the regulating procedure is implemented on the considered anaerobic digestion process in order to validate and demonstrate its efficiency in real life experiments.

  18. [Sulfa-drug wastewater treatment with anaerobic/aerobic process].

    PubMed

    Wu, L; Zhang, H; Zhu, H; Zhang, Z; Zhuang, Y; Dai, S

    2001-09-01

    Sulfa drug wastewater was treated with anaerobic/aerobic process. The removal ratios of TOC reached about 50% in anaerobic phase and about 70% in aerobic phase respectively, while volume loading rate of TOC was about 1.2 kg/(m3.d) in anaerobic phase and about 0.6 kg/(m3.d) in aerobic phase. Removal of TOC in anaerobic phase was attributed to the reduction of sulfate.

  19. Convenient anaerobic techniques, science from the supermarket shelf.

    PubMed

    Bennett, G N; Hickford, J G H; Zhou, H

    2006-02-01

    We describe the application and evaluation of a widely available commercial jar as an anaerobic container suitable for the growth of a wide variety of anaerobes. A system for generating stable anaerobiosis was developed by combining standard anaerobic environment generators with Click-Clack jars produced by Click-Clack Ltd. This system was simple, reliable, and reduced capital outlay on anaerobic jars by at least an order of magnitude.

  20. 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

  1. Direct conversion technology

    SciTech Connect

    Massier, P.F.; Back, L.H.; Ryan, M.A.; Fabris, G.

    1992-01-07

    The overall objective of the Direct Conversion Technology task is to develop an experimentally verified technology base for promising direct conversion systems that have potential application for energy conservation in the end-use sectors. This report contains progress of research on the Alkali Metal Thermal-to-Electric Converter (AMTEC) and on the Two-Phase Liquid-Metal MHD Electrical Generator (LMMHD) for the period January 1, 1991 through December 31, 1991. Research on AMTEC and on LMMHD was initiated during October 1987. Reports prepared on previous occasions (Refs. 1--5) contain descriptive and performance discussions of the following direct conversion concepts: thermoelectric, pyroelectric, thermionic, thermophotovoltaic, thermoacoustic, thermomagnetic, thermoelastic (Nitionol heat engine); and also, more complete descriptive discussions of AMTEC and LMMHD systems.

  2. Frequency conversion system

    NASA Technical Reports Server (NTRS)

    Sanders, Steven (Inventor); Waarts, Robert G. (Inventor)

    2001-01-01

    A frequency conversion system comprises first and second gain sources providing first and second frequency radiation outputs where the second gain source receives as input the output of the first gain source and, further, the second gain source comprises a Raman or Brillouin gain fiber for wave shifting a portion of the radiation of the first frequency output into second frequency radiation output to provided a combined output of first and second frequencies. Powers are gain enhanced by the addition of a rare earth amplifier or oscillator, or a Raman/Brillouin amplifier or oscillator between the high power source and the NFM device. Further, polarization conversion using Raman or Brillouin wavelength shifting is provided to optimize frequency conversion efficiency in the NFM device.

  3. Overview of coal conversion

    SciTech Connect

    Clark, B.R.

    1981-03-27

    The structure of coal and the processes of coal gasification and coal liquefaction are reviewed. While coal conversion technology is not likely to provide a significant amount of synthetic fuel within the next several years, there is a clear interest both in government and private sectors in the development of this technology to hedge against ever-diminishing petroleum supplies, especially from foreign sources. It is evident from this rather cursory survey that there is some old technology that is highly reliable; new technology is being developed but is not ready for commercialization at the present state of development. The area of coal conversion is ripe for exploration both on the applied and basic research levels. A great deal more must be understood about the reactions of coal, the reactions of coal products, and the physics and chemistry involved in the various stages of coal conversion processes in order to make this technology economically viable.

  4. Direct conversion technology

    NASA Technical Reports Server (NTRS)

    Massier, Paul F.; Bankston, C. P.; Williams, R.; Underwood, M.; Jeffries-Nakamura, B.; Fabris, G.

    1989-01-01

    The overall objective of the Direct Conversion Technology task is to develop an experimentally verified technology base for promising direct conversion systems that have potential application for energy conservation in the end-use sectors. This report contains progress of research on the Alkali Metal Thermal-to-Electric Converter (AMTEC), and on the Two-Phase Liquid-Metal Magnetohydrodynamic Electrical Generator (LMMHD) for the period January 1, 1989 through December 31, 1989. Research on these concepts was initiated during October 1987. Reports prepared on previous occasions contain discussions on the following other direct conversion concepts: thermoelectric, pyroelectric, thermionic, thermophotovoltaic, thermoacoustic, thermomagnetic, thermoelastic (nitinol heat engines); and also, more complete discussions of AMTEC and LMMHD systems.

  5. Digital optical conversion module

    DOEpatents

    Kotter, Dale K.; Rankin, Richard A.

    1991-02-26

    A digital optical conversion module used to convert an analog signal to a computer compatible digital signal including a voltage-to-frequency converter, frequency offset response circuitry, and an electrical-to-optical converter. Also used in conjunction with the digital optical conversion module is an optical link and an interface at the computer for converting the optical signal back to an electrical signal. Suitable for use in hostile environments having high levels of electromagnetic interference, the conversion module retains high resolution of the analog signal while eliminating the potential for errors due to noise and interference. The module can be used to link analog output scientific equipment such as an electrometer used with a mass spectrometer to a computer.

  6. Digital optical conversion module

    DOEpatents

    Kotter, D.K.; Rankin, R.A.

    1988-07-19

    A digital optical conversion module used to convert an analog signal to a computer compatible digital signal including a voltage-to-frequency converter, frequency offset response circuitry, and an electrical-to-optical converter. Also used in conjunction with the digital optical conversion module is an optical link and an interface at the computer for converting the optical signal back to an electrical signal. Suitable for use in hostile environments having high levels of electromagnetic interference, the conversion module retains high resolution of the analog signal while eliminating the potential for errors due to noise and interference. The module can be used to link analog output scientific equipment such as an electrometer used with a mass spectrometer to a computer. 2 figs.

  7. Kinetic and thermodynamic control of butyrate conversion in non-defined methanogenic communities.

    PubMed

    Junicke, H; van Loosdrecht, M C M; Kleerebezem, R

    2016-01-01

    Many anaerobic conversions proceed close to thermodynamic equilibrium and the microbial groups involved need to share their low energy budget to survive at the thermodynamic boundary of life. This study aimed to investigate the kinetic and thermodynamic control mechanisms of the electron transfer during syntrophic butyrate conversion in non-defined methanogenic communities. Despite the rather low energy content of butyrate, results demonstrate unequal energy sharing between the butyrate-utilizing species (17 %), the hydrogenotrophic methanogens (9-10 %), and the acetoclastic methanogens (73-74 %). As a key finding, the energy disproportion resulted in different growth strategies of the syntrophic partners. Compared to the butyrate-utilizing partner, the hydrogenotrophic methanogens compensated their lower biomass yield per mole of electrons transferred with a 2-fold higher biomass-specific electron transfer rate. Apart from these thermodynamic control mechanisms, experiments revealed a ten times lower hydrogen inhibition constant on butyrate conversion than proposed by the Anaerobic Digestion Model No. 1, suggesting a much stronger inhibitory effect of hydrogen on anaerobic butyrate conversion. At hydrogen partial pressures exceeding 40 Pa and at bicarbonate limited conditions, a shift from methanogenesis to reduced product formation was observed which indicates an important role of the hydrogen partial pressure in redirecting electron fluxes towards reduced products such as butanol. The findings of this study demonstrate that a careful consideration of thermodynamics and kinetics is required to advance our current understanding of flux regulation in energy-limited syntrophic ecosystems.

  8. Predictability of Conversation Partners

    NASA Astrophysics Data System (ADS)

    Takaguchi, Taro; Nakamura, Mitsuhiro; Sato, Nobuo; Yano, Kazuo; Masuda, Naoki

    2011-08-01

    Recent developments in sensing technologies have enabled us to examine the nature of human social behavior in greater detail. By applying an information-theoretic method to the spatiotemporal data of cell-phone locations, [C. Song , ScienceSCIEAS0036-8075 327, 1018 (2010)] found that human mobility patterns are remarkably predictable. Inspired by their work, we address a similar predictability question in a different kind of human social activity: conversation events. The predictability in the sequence of one’s conversation partners is defined as the degree to which one’s next conversation partner can be predicted given the current partner. We quantify this predictability by using the mutual information. We examine the predictability of conversation events for each individual using the longitudinal data of face-to-face interactions collected from two company offices in Japan. Each subject wears a name tag equipped with an infrared sensor node, and conversation events are marked when signals are exchanged between sensor nodes in close proximity. We find that the conversation events are predictable to a certain extent; knowing the current partner decreases the uncertainty about the next partner by 28.4% on average. Much of the predictability is explained by long-tailed distributions of interevent intervals. However, a predictability also exists in the data, apart from the contribution of their long-tailed nature. In addition, an individual’s predictability is correlated with the position of the individual in the static social network derived from the data. Individuals confined in a community—in the sense of an abundance of surrounding triangles—tend to have low predictability, and those bridging different communities tend to have high predictability.

  9. Waste to Energy Potential - A High Concentration Anaerobic Bioreactor

    DTIC Science & Technology

    2012-05-23

    output • Uses the organic portion of solid waste (such as food waste , paper products, and agricultural waste ) to fuel an anaerobic digestion ...Sustainability Symposium & Exhibition Anaerobic Digestion • What does it do? • Offers sustainability by addressing renewable energy, waste ... Waste to Energy Potential – A High Concentration Anaerobic Bioreactor Presenter: Scott Murphy & Rebecca Robbennolt ARCADIS/Malcolm Pirnie Date

  10. 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…

  11. 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…

  12. 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…

  13. ADEPT: Efficient Power Conversion

    SciTech Connect

    2011-01-01

    ADEPT Project: In today’s increasingly electrified world, power conversion—the process of converting electricity between different currents, voltage levels, and frequencies—forms a vital link between the electronic devices we use every day and the sources of power required to run them. The 14 projects that make up ARPA-E’s ADEPT Project, short for “Agile Delivery of Electrical Power Technology,” are paving the way for more energy efficient power conversion and advancing the basic building blocks of power conversion: circuits, transistors, inductors, transformers, and capacitors.

  14. Power conversion technologies

    SciTech Connect

    Haigh, R E

    1998-01-01

    The Power Conservation Technologies thrust area supports initiatives that enhance the core competencies of the Lawrence Livermore National Laboratory (LLNL) Engineering Directorate in the area of solid-state power electronics. Through partnerships with LLNL programs, projects focus on the development of enabling technologies for existing and emerging programs that have unique power conversion requirements. This year, a multi-disciplinary effort was supported which demonstrated solid-state, high voltage generation by using a dense, monolithic photovoltaic array. This effort builds upon Engineering's strengths in the core technology areas of power conversion, photonics, and microtechnologies.

  15. Direct Conversion Technology

    SciTech Connect

    Back, L.H.; Fabris, G.; Ryan, M.A.

    1992-07-01

    The overall objective of the Direct Conversion Technology task is to develop an experimentally verified technology base for promising direct conversion systems that have potential application for energy conservation in the end-use sectors. Initially, two systems were selected for exploratory research and advanced development. These are Alkali Metal Thermal-to-Electric Converter (AMTEC) and Two-Phase Liquid Metal MD Generator (LMMHD). This report describes progress that has been made during the first six months of 1992 on research activities associated with these two systems. (GHH)

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

    SciTech Connect

    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 that 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.

  17. Studies on upflow anaerobic filter

    NASA Astrophysics Data System (ADS)

    Varandani, Nanik Sobhraj

    The thesis presents a critical review of the available literature on the various studies carried out on various aspects of Upflow Anaerobic Filter (UAF) throughout the world. Young and McCarty (1969) did the pioneering work in developing UAF in 1969, since then several studies have been carried out by different researchers using different substrates under different operating conditions and variety of supporting media. However, the most significant modification of the original reactor developed by Young and McCarty (1968), has been the development and use of high porosity media. The use of high porosity media, in fact, has changed the character of the reactor, from basically a fixed film reactor to a fixed film reactor in which the contribution by the suspended bio-solids, entrapped in the numerous media pores, in the substrate removal is quite significant that is to say that the reactor no longer remains a biological reactor which can be modeled and designed on the basis of biofilm kinetics only. The thesis presents an attempt to validate the developed mathematical model(s) by using the laboratory scale reactor performance data and the calculated values of reaction kinetic and bio-kinetic constants. To simplify the verification process, computer programmes have been prepared using the "EXCELL" software and C language. The results of the "EXCELL" computer program runs are tabulated at table no. 7.1 to 7.5. The verification of various mathematical models indicate that the model III B, i.e. Non ideal plug flow model assumed to consist of Complete Mix Reactors in series based on reaction kinetics, gives results with least deviation from the real situation. An interesting observation being that the model offers least deviation or nearly satisfies the real situation for a particular COD removal efficiency, for a particular OLR, eg. the least deviations are obtained at COD removal efficiency of 89% for OLR 2, 81.5% for OLR 4, 78.5% for OLR 6 . However, the use of the

  18. Anaerobic Digestion in a Flooded Densified Leachbed

    NASA Technical Reports Server (NTRS)

    Chynoweth, David P.; Teixeira, Arthur A.; Owens, John M.; Haley, Patrick J.

    2009-01-01

    A document discusses the adaptation of a patented biomass-digesting process, denoted sequential batch anaerobic composting (SEBAC), to recycling of wastes aboard a spacecraft. In SEBAC, high-solids-content biomass wastes are converted into methane, carbon dioxide, and compost.

  19. Anaerobic threshold measurements of elite oarsmen.

    PubMed

    Mickelson, T C; Hagerman, F C

    1982-01-01

    Anaerobic threshold (AT) and Vo2max were determined by automated analysis for 25 members of the 1980 U.S. Olympic Rowing Team during a progressive rowing ergometer exercise to exhaustion. Heart rates and power outputs were also measured to gauge severity of the exercise and to compare with metabolic data. Power increments of 27 W each min were achieved by progressively increasing the brake weight resistance on the ergometer while maintaining a stroke rate of 28-32 strokes/min and spinning the ergometer flywheel at 550 rpm. Anaerobic threshold measurements were determined by observing the onset of the non-linear relationship between Vo2 and VE-Vco2; plots of delta FEO2 and FECO2 were also utilized to confirm recorded AT's. A mean AT of 83% of Vo2max attests to the high aerobic capacity of oarsmen and supports previous research conducted with these subjects. Power output data indicated that 72% of total power is generated at AT; this substantiates previous energy cost data recorded during simulated rowing during which work was 70% aerobic and 30% anaerobic. High levels of anaerobic thresholds among oarsmen are attributed to the specific nature of training regimens that increase oxidative capacity of muscle fibers and significantly improve the cardiorespiratory transport system. Measurement of heart rate at AT has provided coaches and athletes an objective method of determining the intensity of training sessions.

  20. Anaerobic Toxicity of Cationic Silver Nanoparticles

    EPA Science Inventory

    The microbial toxicity of silver nanoparticles (AgNPs) stabilized with different capping agents was compared to that of Ag+ under anaerobic conditions. Three AgNPs were investigated: (1) negatively charged citrate-coated AgNPs (citrate-AgNPs), (2) minimally charged p...

  1. 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.

  2. Anaerobic Toxicity of Cationic Silver Nanoparticles

    EPA Science Inventory

    The microbial toxicity of silver nanoparticles (AgNPs) stabilized with different capping agents was compared to that of Ag+ under anaerobic conditions. Three AgNPs were investigated: (1) negatively charged citrate-coated AgNPs (citrate-AgNPs), (2) minimally charged p...

  3. The anaerobic digestion of organic solid wastes

    SciTech Connect

    Hartung, H.A.

    1996-09-01

    Anaerobic digestion offers many advantages in the processing of organic solid wastes, using a closed system to convert the waste to combustible gas and a stabilized organic residue.Odors are contained while digestion removes their source and gas is collected for energy recovery as heat or electricity. The stabilized residue is less than the starting waste by the mass of gas produced, and it can be disposed of by land application, land filling, incineration or composting. The stimulation of digesters and the phenomenon of co-digestion are two ways the performance of anaerobic digesters can be enhanced. Data from farm digesters and municipal wastewater treatment plants illustrate the present venue of the process; laboratory studies of the anaerobic digestion of a variety of solid wastes show that the process can be applied to these materials as well. About two thirds of municipal solid waste is shown to be amenable to anaerobic digestion in a substrate from an active municipal sewage plant digester.

  4. Optimizing anaerobic soil disinfestation for California strawberries

    USDA-ARS?s Scientific Manuscript database

    Anaerobic soil disinfestation (ASD), a biological alternative to soil fumigation, can control soilborne pathogens and nematodes in numerous crop production systems. To optimize ASD for California strawberries, a series of field and pot experiments have been conducted since 2003. Overall, ASD treatme...

  5. Early Microbial Evolution: The Age of Anaerobes.

    PubMed

    Martin, William F; Sousa, Filipa L

    2015-12-18

    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. Copyright © 2016 Cold Spring Harbor Laboratory Press; all rights reserved.

  6. Circadian rhythm in anaerobic power and capacity.

    PubMed

    Hill, D W; Smith, J C

    1991-03-01

    Anaerobic power and capacity were measured in nine college-age men at four different times of day: 03.00 h, 09.00 h, 15.00 h, and 21.00 h. Modified Wingate tests were performed against a common resistance of 5.5 kg (0.074 +/- 0.004 kg per kg body mass). Peak power was defined as the highest power output during a 5-s period in the test, and anaerobic capacity was defined as the total external work during the 30-s test. Peak power tended to differ across testing times (F = 2.50, p = .10), with the mean at 21.00 h about 8% higher (p less than .05) than at 03.00 h. Anaerobic capacity differed across the times of day (F = 9.58, p less than .01), with the means at 15.00 h and 21.00 h about 5% higher (p less than .05) than at 03.00 h and 09.00 h. These results suggest that there are circadian rhythms in anaerobic power and capacity.

  7. Gender differences in anaerobic power tests.

    PubMed

    Mayhew, J L; Salm, P C

    1990-01-01

    The purpose of this study was to determine if the differences in anaerobic power between males and females could be accounted for by differences in body composition, strength, and neuromuscular function. A total of 82 untrained men and 99 women took part in the study. Body composition, somatotype, isometric strength, neuromuscular function were measured, and four anaerobic power tests performed. The men were significantly different from the women on all strength, power, and neuromuscular measurements except reaction time and on all anthropometric and somatotype dimensions except ectomorphy. Strength and anthropometric dimensions were similarly related to anaerobic power values within each sex. Relative fat (%fat) exerted different degrees of influence on sprint and jump performances in each sex. Removing the influence of anthropometric, strength, and neuromuscular differences by analysis of covariance reduced, but did not remove, the significant differences between the sexes. Therefore, factors other than lean body mass, leg strength, and neuromuscular function may be operating in short-term, explosive power performances to account for the differences between the sexes. The task-specific nature of anaerobic power tests and the relatively large influence of anthropometric factors on power production were confirmed.

  8. Biofilm-growing intestinal anaerobic bacteria.

    PubMed

    Donelli, Gianfranco; Vuotto, Claudia; Cardines, Rita; Mastrantonio, Paola

    2012-07-01

    Sessile growth of anaerobic bacteria from the human intestinal tract has been poorly investigated, so far. We recently reported data on the close association existing between biliary stent clogging and polymicrobial biofilm development in its lumen. By exploiting the explanted stents as a rich source of anaerobic bacterial strains belonging to the genera Bacteroides, Clostridium, Fusobacterium, Finegoldia, Prevotella, and Veillonella, the present study focused on their ability to adhere, to grow in sessile mode and to form in vitro mono- or dual-species biofilms. Experiments on dual-species biofilm formation were planned on the basis of the anaerobic strains isolated from each clogged biliary stent, by selecting those in which a couple of anaerobic strains belonging to different species contributed to the polymicrobial biofilm development. Then, strains were investigated by field emission scanning electron microscopy and confocal laser scanning microscopy to reveal if they are able to grow as mono- and/or dual-species biofilms. As far as we know, this is the first report on the ability to adhere and form mono/dual-species biofilms exhibited by strains belonging to the species Bacteroides oralis, Clostridium difficile, Clostridium baratii, Clostridium fallax, Clostridium bifermentans, Finegoldia magna, and Fusobacterium necrophorum. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  9. Hemicellulases from anaerobic thermophiles. Progress report

    SciTech Connect

    Wiegel, J.

    1994-05-01

    The longterm goal of this research effort is to obtain an anaerobic thermophilic bacterium that efficiently converts various hemicellulose-containing biomass to ethanol over a broad pH range. The strategy is to modify the outfit and regulation of the rate-limiting xylanases, glycosidases and xylan esterases in the ethanologenic, anaerobic thermophile Thermoanaerobacter ethanolicus, which grows between pH 4.5 and 9.5. Although it utilizes xylans, the xylanase, acetyl(xylan) esterase and O-methylglucuronidase activities in T. ethanolicus are barely measurable and regarded as the rate limiting steps in its xylan utilization. Thus, and also due to the presently limited knowledge of hemicellulases in anaerobic thermophiles, we characterize the hemicellulolytic enzymes from this and other anaerobic thermophiles as enzyme donors. Beside the active xylosidase/arabinosidase from T. ethanolicus, exhibiting the two different activities, we characterized 2 xylosidases, two acetyl(xylan) esterases, and an O-methylglucuronidase from Thermoanaerobacterium spec. We will continue with the characterization of xylanases from novel isolated slightly acidophilic, neutrophilic and slightly alkalophilic thermophiles. We have cloned, subcloned and partially sequenced the 165,000 Da (2 x 85,000) xylosidase/arabinosidase from T. ethanolicus and started with the cloning of the esterases from Thermoanaerobacterium spec. Consequently, we will develop a shuttle vector and continue to apply electroporation of autoplasts as a method for cloning into T. ethanolicus.

  10. Monitoring the Atmosphere in an Anaerobic Chamber

    PubMed Central

    Sudo, Sara Z.; Hersch, Paul A.

    1974-01-01

    The Couloximeter, a fuel cell designed to measure trace amounts of oxygen, was used to monitor the atmosphere in an anaerobic chamber. The device, easy to operate and to maintain, allowed both major and minor fluctuations in oxygen concentration to be measured. Using a hose attached to the outlet within the box, defective (ruptured) gloves were consistently distinguishable from intact gloves. PMID:16350004

  11. 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

  12. Engineering and two-stage evolution of a lignocellulosic hydrolysate-tolerant Saccharomyces cerevisiae strain for anaerobic fermentation of xylose from AFEX pretreated corn stover.

    PubMed

    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.

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

    DTIC Science & Technology

    2009-12-01

    including football, sprinting, soccer, baseball, lacrosse, and gymnastics - use anaerobic metabolism extensively during competition. This study...1 . 3 62j + 7.7 167.1 + 7 .9 Tennis, track, soccer, and gymnastics urements allow a coach to observe individual improvements; however, it is...require short bursts of peak power and a high anaerobic capacity during competition to include lacrosse, gymnastics , sprint cycling, football, baseball

  14. Planetary image conversion task

    NASA Technical Reports Server (NTRS)

    Martin, M. D.; Stanley, C. L.; Laughlin, G.

    1985-01-01

    The Planetary Image Conversion Task group processed 12,500 magnetic tapes containing raw imaging data from JPL planetary missions and produced an image data base in consistent format on 1200 fully packed 6250-bpi tapes. The output tapes will remain at JPL. A copy of the entire tape set was delivered to US Geological Survey, Flagstaff, Ariz. A secondary task converted computer datalogs, which had been stored in project specific MARK IV File Management System data types and structures, to flat-file, text format that is processable on any modern computer system. The conversion processing took place at JPL's Image Processing Laboratory on an IBM 370-158 with existing software modified slightly to meet the needs of the conversion task. More than 99% of the original digital image data was successfully recovered by the conversion task. However, processing data tapes recorded before 1975 was destructive. This discovery is of critical importance to facilities responsible for maintaining digital archives since normal periodic random sampling techniques would be unlikely to detect this phenomenon, and entire data sets could be wiped out in the act of generating seemingly positive sampling results. Reccomended follow-on activities are also included.

  15. Clinical Linguistics: Conversational Reflections

    ERIC Educational Resources Information Center

    Crystal, David

    2013-01-01

    This is a report of the main points I made in an informal "conversation" with Paul Fletcher and the audience at the 14th ICPLA conference in Cork. The observations arose randomly, as part of an unstructured 1-h Q&A, so they do not provide a systematic account of the subject, but simply reflect the issues which were raised by the conference…

  16. Stories in Conversation.

    ERIC Educational Resources Information Center

    Hofer, Roberta Senner

    Although conversational stories within one individual's corpus share the same structure, they have features that set them apart from one another. Based on the stories' general characteristics and the way they function in ongoing talk, they can be identified as: (1) durable personal experience narratives (PENs), which are often repeated during the…

  17. Evaluating Energy Conversion Efficiency

    NASA Technical Reports Server (NTRS)

    Byvik, C. E.; Smith, B. T.; Buoncristiani, A. M.

    1983-01-01

    Devices that convert solar radiation directly into storable chemical or electrical energy, have characteristic energy absorption spectrum; specifically, each of these devices has energy threshold. The conversion efficiency of generalized system that emcompasses all threshold devices is analyzed, resulting in family of curves for devices of various threshold energies operating at different temperatures.

  18. A Conversation about Observation

    NASA Technical Reports Server (NTRS)

    Mather, John C.; Mao, Minnie Yuan

    2012-01-01

    In the spirit of the Lindau Meeting, we present a dialogue between a Nobel laureate and a young researcher. This interchange started online, where it continues to unfold. Here is a digest of this conversation, which has developed across time and space.

  19. Conversations and Collaborations

    ERIC Educational Resources Information Center

    Korpan, Cynthia

    2010-01-01

    This paper looks at how a series of conversations contributed to the development of a newly formed role at the University of Victoria--Teaching Assistant Consultants (TACs). TACs act as departmental mentors for teaching assistants (TAs) in their respective departments, charged with providing support in the form of discipline-specific workshops…

  20. Clinical Linguistics: Conversational Reflections

    ERIC Educational Resources Information Center

    Crystal, David

    2013-01-01

    This is a report of the main points I made in an informal "conversation" with Paul Fletcher and the audience at the 14th ICPLA conference in Cork. The observations arose randomly, as part of an unstructured 1-h Q&A, so they do not provide a systematic account of the subject, but simply reflect the issues which were raised by the conference…

  1. Ocean thermal energy conversion

    SciTech Connect

    Avery, W.H.

    1983-03-17

    A brief explanation of the Ocean Thermal Energy Conversion (OTEC) concept and an estimate of the amount of energy that can be produced from the ocean resource without introducing environmental concerns are presented. Use of the OTEC system to generate electric power and products which can replace fossil fuels is shown. The OTEC program status and its prospects for the future are discussed.

  2. Electromechanical Energy Conversion.

    ERIC Educational Resources Information Center

    LePage, Wilbur R.

    This programed text on electromechanical energy conversion (motors and generators) was developed under contract with the U.S. Office of Education as Number 12 in a series of materials for use in an electrical engineering sequence. It is intended to be used in conjunction with other materials and with other short texts in the series. (DH)

  3. Evaluating Energy Conversion Efficiency

    NASA Technical Reports Server (NTRS)

    Byvik, C. E.; Smith, B. T.; Buoncristiani, A. M.

    1983-01-01

    Devices that convert solar radiation directly into storable chemical or electrical energy, have characteristic energy absorption spectrum; specifically, each of these devices has energy threshold. The conversion efficiency of generalized system that emcompasses all threshold devices is analyzed, resulting in family of curves for devices of various threshold energies operating at different temperatures.

  4. Conversational English Program, 2.

    ERIC Educational Resources Information Center

    Instituto de Idiomas Yazigi, Sao Paulo (Brazil). Centro de Linguistica Aplicada.

    This second book of a conversational English program for adults contains an introductory section in Portuguese and exercises in English. The text centers around an English-speaking family from the United States that goes to live in Brazil. It contains color photographs with captions followed by exercises. The exercises are in English and involve…

  5. Mechanochemical Energy Conversion

    ERIC Educational Resources Information Center

    Pines, E.; And Others

    1973-01-01

    Summarizes the thermodynamics of macromolecular systems, including theories and experiments of cyclic energy conversion with rubber and collagen as working substances. Indicates that an early introduction into the concept of chemical potential and solution thermodynamics is made possible through the study of the cyclic processes. (CC)

  6. Conversational English Program, 1.

    ERIC Educational Resources Information Center

    Instituto de Idiomas Yazigi, Sao Paulo (Brazil). Centro de Linguistica Aplicada.

    This first book of a conversational English program for adults contains an introductory section in Portuguese and exercises in English. The text centers around an English-speaking family from the United States that goes to live in Brazil. It contains color photographs with captions followed by exercises. The exercises are in English and involve…

  7. Mechanochemical Energy Conversion

    ERIC Educational Resources Information Center

    Pines, E.; And Others

    1973-01-01

    Summarizes the thermodynamics of macromolecular systems, including theories and experiments of cyclic energy conversion with rubber and collagen as working substances. Indicates that an early introduction into the concept of chemical potential and solution thermodynamics is made possible through the study of the cyclic processes. (CC)

  8. Leadership is a conversation.

    PubMed

    Groysberg, Boris; Slind, Michael

    2012-06-01

    Globalization and new technologies have sharply reduced the efficacy of command-and-control management and its accompanying forms of corporate communication. In the course of a recent research project, the authors concluded that by talking with employees, rather than simply issuing orders, leaders can promote operational flexibility, employee engagement, and tight strategic alignment. Groysberg and Slind have identified four elements of organizational conversation that reflect the essential attributes of interpersonal conversation: intimacy, interactivity, inclusion, and intentionality. Intimacy shifts the focus from a top-down distribution of information to a bottom-up exchange of ideas. Organizational conversation is less corporate in tone and more casual. And it's less about issuing and taking orders than about asking and answering questions. Interactivity entails shunning the simplicity of monologue and embracing the unpredictable vitality of dialogue. Traditional one-way media-print and broadcast, in particular-give way to social media buttressed by social thinking. Inclusion turns employees into full-fledged conversation partners, entitling them to provide their own ideas, often on company channels. They can create content and act as brand ambassadors, thought leaders, and storytellers. Intentionality enables leaders and employees to derive strategically relevant action from the push and pull of discussion and debate.

  9. Conversations on ecology IV

    USGS Publications Warehouse

    Leopold, Luna Bergere

    1963-01-01

    The conversations on ecology have mentioned the pesticide problem, and in such discussion it is easy to lose sight of the basic philosophic view which is an undercurrent in Miss Carson's book. I should like to expand on that philosophic premise and examine some of its implications for planning vegetation management measures as well as other measures for resource development.

  10. Conversion or New Building?

    ERIC Educational Resources Information Center

    Berkeley, Phil

    1970-01-01

    Examined first is "the overall problem of housing a TV studio complex to see what particular sorts of buildings are required and how they must be related," and then considered are "the relative merits and particular problems of new studio building or a conversion." (LS)

  11. Solar energy conversion.

    SciTech Connect

    Crabtree, G. W.; Lewis, N. S.

    2008-03-01

    If solar energy is to become a practical alternative to fossil fuels, we must have efficient ways to convert photons into electricity, fuel, and heat. The need for better conversion technologies is a driving force behind many recent developments in biology, materials, and especially nanoscience. The Sun has the enormous untapped potential to supply our growing energy needs. The barrier to greater use of the solar resource is its high cost relative to the cost of fossil fuels, although the disparity will decrease with the rising prices of fossil fuels and the rising costs of mitigating their impact on the environment and climate. The cost of solar energy is directly related to the low conversion efficiency, the modest energy density of solar radiation, and the costly materials currently required. The development of materials and methods to improve solar energy conversion is primarily a scientific challenge: Breakthroughs in fundamental understanding ought to enable marked progress. There is plenty of room for improvement, since photovoltaic conversion efficiencies for inexpensive organic and dye-sensitized solar cells are currently about 10% or less, the conversion efficiency of photosynthesis is less than 1%, and the best solar thermal efficiency is 30%. The theoretical limits suggest that we can do much better. Solar conversion is a young science. Its major growth began in the 1970s, spurred by the oil crisis that highlighted the pervasive importance of energy to our personal, social, economic, and political lives. In contrast, fossil-fuel science has developed over more than 250 years, stimulated by the Industrial Revolution and the promise of abundant fossil fuels. The science of thermodynamics, for example, is intimately intertwined with the development of the steam engine. The Carnot cycle, the mechanical equivalent of heat, and entropy all played starring roles in the development of thermodynamics and the technology of heat engines. Solar-energy science faces

  12. Recovery of anaerobic, facultative, and aerobic bacteria from clinical specimens in three anaerobic transport systems.

    PubMed

    Helstad, A G; Kimball, J L; Maki, D G

    1977-06-01

    With aspirated specimens from clinical infections, we evaluated the recovery of anaerobic, aerobic, and facultative bacteria in three widely used transport systems: (i) aspirated fluid in a gassed-out tube (FGT), (ii) swab in modified Cary and Blair transport medium (SCB), and (iii) swab in a gassed-out tube (SGT). Transport tubes were held at 25 degrees C and semiquantitatively sampled at 0, 2, 24, and 48 h. Twenty-five clinical specimens yielded 75 anaerobic strains and 43 isolates of facultative and 3 of aerobic bacteria. Only one anaerobic isolate was not recovered in the first 24 h, and then, only in the SGT. At 48 h, 73 anaerobic strains (97%) were recovered in the FGT, 69 (92%) in the SCB, and 64 (85%) in the SGT. Two problems hindered the recovery of anaerobes in the SCB and SGT systems: first die-off of organisms, as evidenced by a decrease in colony-forming units of 20 strains (27%) in the SCB and 25 strains (33%) in the SGT, as compared with 7 strains (9%) in the FGT, over 48 h; and second, overgrowth of facultative bacteria, more frequent with SCB and SGT. The FGT method was clearly superior at 48 h to the SCB and SGT systems in this study and is recommended as the preferred method for transporting specimens for anaerobic culture.

  13. Anaerobic characteristics in male children and adolescents.

    PubMed

    Inbar, O; Bar-Or, O

    1986-06-01

    Only sparse information has been published on the effects of growth, development, and maturation on the ability to perform high intensity, short-term "anaerobic" tasks. Cross-sectional studies on Italian, African, British, and American females and males have indicated an age-related progression in the performance of the Margaria step-running test. Children had a distinctly lower mechanical power output than adolescents and young adults, both in absolute terms and when divided by body weight, or by fat-free mass. Data are presented on some 300 10- to 45-yr-old Israeli males who performed the Wingate anaerobic test by cycling or by arm cranking. Both the peak power at any 5-s period and the mean power throughout the test were lowest in the children, whether expressed in absolute power units or corrected for body weight. Performance progressed with age and reached the highest values at the end of the third decade for cycling and at the end of the second decade for arm cranking. This pattern is unlike that described for maximal O2 uptake per kg body weight which, in males, remains virtually unchanged from childhood to young adulthood. In females, maximal O2 uptake per kg is even higher in children than among adolescents or adults. Biochemical correlates of such a low anaerobic performance in children are their lower maximal lactate concentration in muscle and blood, lower rate of anaerobic glycolysis, and lower levels of acidosis at maximal exercise. The mechanisms for the relatively deficient anaerobic characteristics of children are not clear.

  14. Anaerobic benzene oxidation by Geobacter species.

    PubMed

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

    2012-12-01

    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 × 10(9) and 8.4 × 10(9) 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 × 10(9) 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.

  15. 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

  16. Anaerobic protozoa and their growth in biomethanation systems.

    PubMed

    Priya, M; Haridas, Ajit; Manilal, V B

    2008-04-01

    This study was to investigate growth of protozoa and its influence on biodegradation in anaerobic treatment systems. It was done by specifically controlling and monitoring growth of protozoa versus degradation in continuous stirred anaerobic reactors and batch anaerobic reactors. Occurrence of a diverse protozoa population such as the ciliates, Prorodon, Vorticella, Cyclidium, Spathidium, Loxodes, Metopus were observed in stable anaerobic systems and the flagellates, Rhynchomonas, Naeglaria, Amoeboflagellates, Tetramitus, Trepomonas and Bodo during increased VFA concentration and affected periods of biomethanation. The abundance of ciliates in the anaerobic system had significant correlation with the reduction of MLSS, increased rate of COD removal and higher methane production. The results of this study thus tend to relate increased anaerobic degradation with the abundance of protozoa, mainly ciliates, which indicate their possible involvement in the process. Present study also reveals that performance of anaerobic process can be assessed by monitoring the protozoa population in the system.

  17. Metabolic determinants in Listeria monocytogenes anaerobic listeriolysin O production.

    PubMed

    Wallace, Nathan; Newton, Eric; Abrams, Elizabeth; Zani, Ashley; Sun, Yvonne

    2017-03-13

    Listeria monocytogenes is a human pathogen and a facultative anaerobe. To better understand how anaerobic growth affects L. monocytogenes pathogenesis, we first showed that anaerobic growth led to decreased growth and changes in surface morphology. Moreover, compared to aerobically grown bacteria, anaerobically grown L. monocytogenes established higher level of invasion but decreased intracellular growth and actin polymerization in cultured cells. The production of listeriolysin O (LLO) was significantly lower in anaerobic cultures-a phenotype observed in wild type and isogenic mutants lacking transcriptional regulators SigB or CodY or harboring a constitutively active PrfA. To explore potential regulatory mechanisms, we established that the addition of central carbon metabolism intermediates, such as acetate, citrate, fumarate, pyruvate, lactate, and succinate, led to an increase in LLO activity in the anaerobic culture supernatant. These results highlight the regulatory role of central carbon metabolism in L. monocytogenes pathogenesis under anaerobic conditions.

  18. 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

  19. Systematic method for oxidation pond conversion for the production of site specific energy sources

    SciTech Connect

    Werner, E.; Rodriguez, T.

    1981-01-01

    Primary sources of solar derived biomass (sugarcane, wood, and aquatic plants), are of considerable future importance as energy producing substrates. The waste products of agriculture and husbandry represent a viable and potentially significant energy source, also. Solar energy, produced photosynthetically, is available not only by combustion or conversion of plant materials, but also by utilizing metabolic products of succeeding trophic levels. Animal wastes, produced in massive quantities from dairy, swine, and poultry operations, can be converted to energy by the relatively simple and well understood technology of bioconversion, or anaerobic digestion. Currently, the principle method for disposal of these wastes is by oxidation ponds, solving neither environmental nor energy problems. Conversion, in situ of farm oxidation ponds to anaerobic digestion systems, can be easily and economically achieved resulting in development of small site specific decentralized energy sources (methane); simultaneously resolving a rapidly growing environmental and social problem.

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

    SciTech Connect

    Donlon, B.; Razo-Flores, E.; Hwu, C.S.; Field, J.; Lettinga, G.

    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 of 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.