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Sample records for anaerobic conditions

  1. PCB biohalogenation under anaerobic conditions

    SciTech Connect

    Gauger, W.K.; McCue, J.J.

    1990-01-01

    The Institute of Gas Technology (IGT) is conducting research on the biodehalogenation of polychlorinated biphenyls (PCB's) under anoxic conditions. Reductive dechlorination of PCB's has been observed in treatments inoculated with Hudson River sediments. Differences in gas chromatograms between time 0 and 4-month incubations indicate pattern shifts of the PCB homologs that constitute Aroclor 1242 from highly chlorinated to lesser chlorinated congeners. Changes in distribution patterns of PCB homologs were also evident. PCB homologs containing 4, 5, 6, and 7 chlorine atoms were shown to decrease over the incubation period, whereas PCB homologs containing 2 and 3 chlorines increased in concentration. 10 refs., 5 figs., 1 tab.

  2. Anaerobic biodegradation of cyanide under methanogenic conditions

    SciTech Connect

    Fallon, R.D.; Cooper, D.A.; Henson, M. ); Speece, R. )

    1991-06-01

    Upflow, anaerobic, fixed-bed, activated charcoal biotreatment columns capable of operating at free cyanide concentrations of {gt}100 mg liter{sup {minus}1} with a hydraulic retention time of {lt}48 h were developed. Methanogenesis was maintained under a variety of feed medium conditions which included ethanol, phenol, or methanol as the primary reduced carbon source. Under optimal conditions, {gt}70% of the inflow free cyanide was removed in the first 30% of the column height. Strongly complexed cyanides were resistant to removal. Ammonia was the nitrogen end product of cyanide transformation. In cell material removed from the charcoal columns, ({sup 14}C) bicarbonate was the major carbon end product of ({sup 14}C) cyanide transformation.

  3. Anaerobic biodegradation of cyanide under methanogenic conditions.

    PubMed Central

    Fallon, R D; Cooper, D A; Speece, R; Henson, M

    1991-01-01

    Upflow, anaerobic, fixed-bed, activated charcoal biotreatment columns capable of operating at free cyanide concentrations of greater than 100 mg liter-1 with a hydraulic retention time of less than 48 h were developed. Methanogenesis was maintained under a variety of feed medium conditions which included ethanol, phenol, or methanol as the primary reduced carbon source. Under optimal conditions, greater than 70% of the inflow free cyanide was removed in the first 30% of the column height. Strongly complexed cyanides were resistant to removal. Ammonia was the nitrogen end product of cyanide transformation. In cell material removed from the charcoal columns, [14C]bicarbonate was the major carbon end product of [14C]cyanide transformation. PMID:1872600

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

    PubMed Central

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

    2016-01-01

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

  6. Degradation of natural and synthetic polyesters under anaerobic conditions.

    PubMed

    Abou-Zeid, D M; Müller, R J; Deckwer, W D

    2001-03-30

    Often, degradability under anaerobic conditions is desirable for plastics claimed to be biodegradable, e.g. in anaerobic biowaste treatment plants, landfills and in natural anaerobic sediments. The biodegradation of the natural polyesters poly(beta-hydroxybutyrate) (PHB), poly(beta-hydroxybutyrate-co-11.6%-beta-hydroxyvalerate) (PHBV) and the synthetic polyester poly(epsilon-caprolactone) (PCL) was studied in two anaerobic sludges and individual polyester degrading anaerobic strains were isolated, characterized and used for degradation experiments under controlled laboratory conditions. Incubation of PHB and PHBV films in two anaerobic sludges exhibited significant degradation in a time scale of 6-10 weeks monitored by weight loss and biogas formation. In contrast to aerobic conditions, PHB was degraded anaerobically more rapidly than the copolyester PHBV, when tested with either mixed cultures or a single strained isolate. PCL tends to degrade slower than the natural polyesters PHB and PHBV. Four PHB and PCL degrading isolates were taxonomically identified and are obviously new species belonging to the genus Clostridium group I. The depolymerizing enzyme systems of PHB and PCL degrading isolates are supposed to be different. Using one isolated strain in an optimized laboratory degradation test with PHB powder, the degradation time was drastically reduced compared to the degradation in sludges (2 days vs. 6-10 weeks).

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

    SciTech Connect

    Gale, P.M.

    1988-01-01

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

  8. Anaerobic incubation conditions enhance pyrazinamide activity against Mycobacterium tuberculosis.

    PubMed

    Wade, Mary Margaret; Zhang, Ying

    2004-08-01

    Pyrazinamide (PZA) is an unconventional front line tuberculosis drug characterized by high in vivo sterilizing activity, but poor in vitro activity. This disparity in PZA activity may reflect differences between the in vivo tissue environment and in vitro culture conditions. This study examined the effect of anaerobic conditions, which exist in granulomatous lesions in vivo, on PZA activity in vitro. Low oxygen enhanced the activity of PZA against Mycobacterium tuberculosis, with anaerobic conditions resulting in greater enhancement than microaerobic conditions. ATPase and respiratory chain enzyme inhibitors enhanced PZA activity under normal atmospheric conditions, but not under anaerobic conditions. Furthermore, the inhibitors did not enhance isoniazid or rifampicin activity. Nitrate as an alternative electron acceptor antagonized PZA activity under anaerobic conditions. These findings provide further support for a proposed mechanism of action of PZA in which the active form of PZA (pyrazinoic acid) depletes the membrane energy reserve. They also provide another explanation for the higher sterilizing activity of PZA within in vivo lesions with low oxygen than under in vitro drug susceptibility testing conditions with ambient oxygen.

  9. Engineered microorganisms capable of producing target compounds under anaerobic conditions

    DOEpatents

    Buelter, Thomas [Denver, CO; Meinhold, Peter [Denver, CO; Feldman, Reid M. Renny [San Francisco, CA; Hawkins, Andrew C [Parker, CO; Urano, Jun [Irvine, CA; Bastian, Sabine [Pasadena, CA; Arnold, Frances [La Canada, CA

    2012-01-17

    The present invention is generally provides recombinant microorganisms comprising engineered metabolic pathways capable of producing C3-C5 alcohols under aerobic and anaerobic conditions. The invention further provides ketol-acid reductoisomerase enzymes which have been mutated or modified to increase their NADH-dependent activity or to switch the cofactor preference from NADPH to NADH and are expressed in the modified microorganisms. In addition, the invention provides isobutyraldehyde dehydrogenase enzymes expressed in modified microorganisms. Also provided are methods of producing beneficial metabolites under aerobic and anaerobic conditions by contacting a suitable substrate with the modified microorganisms of the present invention.

  10. 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.

  11. Decolorization of azo dyes under batch anaerobic and sequential anaerobic/aerobic conditions.

    PubMed

    Işik, Mustafa; Sponza, Delia Teresa

    2004-01-01

    Batch anaerobic and sequential anaerobic upflow anaerobic sludge blanket (UASB)/aerobic continuous stirred tank reactor (CSTR) were used to determine the color and COD removals under anaerobic/aerobic conditions. Two azo dyes namely "Reactive Black 5 (RB 5)," "Congo Red (CR)," and glucose as a carbon source were used for synthetic wastewater. The course of the decolorization process approximates to first order and zero order kinetics with respect to dye concentration for RB 5 and Congo Red azo dyes, respectively, in batch conditions. The decolorization kinetic constant (K0) values increased from 3.6 to 11.8 mg(L h)(-1) as increases in dye concentrations from 200 to 3200 mg L(-1) for CR. Increases in dye concentrations from 0 to 3200 mg L(-1) reduce the decolorization rate constant (k1) values from 0.0141 to 0.0019 h(-1) in batch studies performed with RB 5. Decolorization was achieved effectively under test conditions but ultimate decolorization of azo dyes was not observed at all dye concentrations in batch assay conditions. Dye concentrations of 100 mg L(-1) and 3000 mg L(-1) of glucose-COD containing basal medium were used for continuous studies. The effect of organic loadings and HRT, on the color removal efficiencies and methane gas productions were monitored. 94.1-45.4% COD and 79-73% color removal efficiencies were obtained at an organic system during decolorization of Reactive Black 5. 92.3-77.0% COD and 95.3-92.2% decolorization efficiencies were achieved at a organic loading rate of 1.03-6.65 kg (m3 day)(-1) and a HRT of 3.54-0.49 for Congo Red treatment. The results of this study showed that, although decolorization continued, COD removal efficiencies and methane gas production were depressed at high organic loadings under anaerobic conditions. Furthermore, VFA accumulation, alkalinity consumption, and methane gas percentage were monitored at organic loading as high as 2.49-4.74 kg (m3 day)(-1) and 24.60-30.62 kg (m3 day)(-1), respectively, through the

  12. Degradation of triclosan under aerobic, anoxic, and anaerobic conditions.

    PubMed

    Gangadharan Puthiya Veetil, Prajeesh; Vijaya Nadaraja, Anupama; Bhasi, Arya; Khan, Sudheer; Bhaskaran, Krishnakumar

    2012-07-01

    Triclosan (2, 4, 4'-trichloro-2'-hydroxyl diphenyl ether) is a broad-spectrum antimicrobial agent present in a number of house hold consumables. Aerobic and anaerobic enrichment cultures tolerating triclosan were developed and 77 bacterial strains tolerating triclosan at different levels were isolated from different inoculum sources. Biodegradation of triclosan under aerobic, anoxic (denitrifying and sulphate reducing conditions), and anaerobic conditions was studied in batch cultures with isolated pure strains and enrichment consortium developed. Under aerobic conditions, the isolated strains tolerated triclosan up to 1 g/L and degraded the compound in inorganic-mineral-broth and agar media. At 10 mg/L level triclosan, 95 ± 1.2% was degraded in 5 days, producing phenol, catechol and 2, 4-dichlorophenol as the degradation products. The strains were able to metabolize triclosan and its degradation products in the presence of monooxygenase inhibitor 1-pentyne. Under anoxic/anaerobic conditions highest degradation (87%) was observed in methanogenic system with acetate as co-substrate and phenol, catechol, and 2, 4-dichlorophenol were among the products. Three of the isolated strains tolerating 1 g/L triclosan were identified as Pseudomonas sp. (BDC 1, 2, and 3).

  13. Anaerobic conditions improve germination of a gibberellic acid deficient rice

    NASA Technical Reports Server (NTRS)

    Frantz, Jonathan M.; Bugbee, Bruce

    2002-01-01

    Dwarf plants are useful in research because multiple plants can be grown in a small area. Rice (Oryza sativa L.) is especially important since its relatively simple genome has recently been sequenced. We are characterizing a gibberellic acid (GA) mutant of rice (japonica cv 'Shiokari,' line N-71) that is extremely dwarf (20 cm tall). Unfortunately, this GA mutation is associated with poor germination (70%) under aerobic conditions. Neither exogenous GA nor a dormancy-breaking heat treatment improved germination. However, 95% germination was achieved by germinating the seeds anaerobically, either in a pure N2 environment or submerged in unstirred tap water. The anaerobic conditions appear to break a mild post-harvest dormancy in this rice cultivar. Copyright 2002 Crop Science Society of America.

  14. Anaerobic conditions improve germination of a gibberellic acid deficient rice

    NASA Technical Reports Server (NTRS)

    Frantz, Jonathan M.; Bugbee, Bruce

    2002-01-01

    Dwarf plants are useful in research because multiple plants can be grown in a small area. Rice (Oryza sativa L.) is especially important since its relatively simple genome has recently been sequenced. We are characterizing a gibberellic acid (GA) mutant of rice (japonica cv 'Shiokari,' line N-71) that is extremely dwarf (20 cm tall). Unfortunately, this GA mutation is associated with poor germination (70%) under aerobic conditions. Neither exogenous GA nor a dormancy-breaking heat treatment improved germination. However, 95% germination was achieved by germinating the seeds anaerobically, either in a pure N2 environment or submerged in unstirred tap water. The anaerobic conditions appear to break a mild post-harvest dormancy in this rice cultivar. Copyright 2002 Crop Science Society of America.

  15. 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 ...

  16. The Effects of Desiccation on Methanogens Under Aerobic and Anaerobic Conditions

    NASA Astrophysics Data System (ADS)

    Murphy, C.; Kral, T. A.

    2010-04-01

    Survival of methanogens following desiccation depends on whether they are maintained under aerobic or anaerobic conditions. Cells maintained in a desiccated state in the presence of oxygen did not survive as well as those maintained anaerobically.

  17. Stabilisation of microalgae: Iodine mobilisation under aerobic and anaerobic conditions.

    PubMed

    Han, Wei; Clarke, William; Pratt, Steven

    2015-10-01

    Mobilisation of iodine during microalgae stabilisation was investigated, with the view of assessing the potential of stabilised microalgae as an iodine-rich fertiliser. An iodine-rich waste microalgae (0.35 ± 0.05 mg I g(-1) VS(added)) was stabilised under aerobic and anaerobic conditions. Iodine mobilisation was linearly correlated with carbon emission, indicating iodine was in the form of organoiodine. Comparison between iodine and nitrogen mobilisation relative to carbon emission indicated that these elements were, at least in part, housed separately within the cells. After stabilisation, there were 0.22 ± 0.05 and 0.19 ± 0.01 mg g(-1) VS(added) iodine remaining in the solid in the aerobic and anaerobic processed material respectively, meaning 38 ± 5.0% (aerobic) and 50 ± 8.6% (anaerobic) of the iodine were mobilised, and consequently lost from the material. The iodine content of the stabilised material is comparable to the iodine content of some seaweed fertilisers, and potentially satisfies an efficient I-fertilisation dose.

  18. Bacterial Drug Tolerance under Clinical Conditions Is Governed by Anaerobic Adaptation but not Anaerobic Respiration

    PubMed Central

    Hemsley, Claudia M.; Luo, Jamie X.; Andreae, Clio A.; Butler, Clive S.; Soyer, Orkun S.

    2014-01-01

    Noninherited antibiotic resistance is a phenomenon whereby a subpopulation of genetically identical bacteria displays phenotypic tolerance to antibiotics. We show here that compared to Escherichia coli, the clinically relevant genus Burkholderia displays much higher levels of cells that tolerate ceftazidime. By measuring the dynamics of the formation of drug-tolerant cells under conditions that mimic in vivo infections, we show that in Burkholderia bacteria, oxygen levels affect the formation of these cells. The drug-tolerant cells are characterized by an anaerobic metabolic signature and can be eliminated by oxygenating the system or adding nitrate. The transcriptome profile suggests that these cells are not dormant persister cells and are likely to be drug tolerant as a consequence of the upregulation of anaerobic nitrate respiration, efflux pumps, β-lactamases, and stress response proteins. These findings have important implications for the treatment of chronic bacterial infections and the methodologies and conditions that are used to study drug-tolerant and persister cells in vitro. PMID:25049258

  19. Bacterial drug tolerance under clinical conditions is governed by anaerobic adaptation but not anaerobic respiration.

    PubMed

    Hemsley, Claudia M; Luo, Jamie X; Andreae, Clio A; Butler, Clive S; Soyer, Orkun S; Titball, Richard W

    2014-10-01

    Noninherited antibiotic resistance is a phenomenon whereby a subpopulation of genetically identical bacteria displays phenotypic tolerance to antibiotics. We show here that compared to Escherichia coli, the clinically relevant genus Burkholderia displays much higher levels of cells that tolerate ceftazidime. By measuring the dynamics of the formation of drug-tolerant cells under conditions that mimic in vivo infections, we show that in Burkholderia bacteria, oxygen levels affect the formation of these cells. The drug-tolerant cells are characterized by an anaerobic metabolic signature and can be eliminated by oxygenating the system or adding nitrate. The transcriptome profile suggests that these cells are not dormant persister cells and are likely to be drug tolerant as a consequence of the upregulation of anaerobic nitrate respiration, efflux pumps, β-lactamases, and stress response proteins. These findings have important implications for the treatment of chronic bacterial infections and the methodologies and conditions that are used to study drug-tolerant and persister cells in vitro. Copyright © 2014 Hemsley et al.

  20. Microbial communities mediating algal detritus turnover under anaerobic conditions

    PubMed Central

    Morrison, Jessica M.; Murphy, Chelsea L.; Baker, Kristina; Zamor, Richard M.; Nikolai, Steve J.; Wilder, Shawn; Elshahed, Mostafa S.

    2017-01-01

    Background Algae encompass a wide array of photosynthetic organisms that are ubiquitously distributed in aquatic and terrestrial habitats. Algal species often bloom in aquatic ecosystems, providing a significant autochthonous carbon input to the deeper anoxic layers in stratified water bodies. In addition, various algal species have been touted as promising candidates for anaerobic biogas production from biomass. Surprisingly, in spite of its ecological and economic relevance, the microbial community involved in algal detritus turnover under anaerobic conditions remains largely unexplored. Results Here, we characterized the microbial communities mediating the degradation of Chlorella vulgaris (Chlorophyta), Chara sp. strain IWP1 (Charophyceae), and kelp Ascophyllum nodosum (phylum Phaeophyceae), using sediments from an anaerobic spring (Zodlteone spring, OK; ZDT), sludge from a secondary digester in a local wastewater treatment plant (Stillwater, OK; WWT), and deeper anoxic layers from a seasonally stratified lake (Grand Lake O’ the Cherokees, OK; GL) as inoculum sources. Within all enrichments, the majority of algal biomass was metabolized within 13–16 weeks, and the process was accompanied by an increase in cell numbers and a decrease in community diversity. Community surveys based on the V4 region of the 16S rRNA gene identified different lineages belonging to the phyla Bacteroidetes, Proteobacteria (alpha, delta, gamma, and epsilon classes), Spirochaetes, and Firmicutes that were selectively abundant under various substrate and inoculum conditions. Within all kelp enrichments, the microbial communities structures at the conclusion of the experiment were highly similar regardless of the enrichment source, and were dominated by the genus Clostridium, or family Veillonellaceae within the Firmicutes. In all other enrichments the final microbial community was dependent on the inoculum source, rather than the type of algae utilized as substrate. Lineages enriched

  1. Microbial communities mediating algal detritus turnover under anaerobic conditions.

    PubMed

    Morrison, Jessica M; Murphy, Chelsea L; Baker, Kristina; Zamor, Richard M; Nikolai, Steve J; Wilder, Shawn; Elshahed, Mostafa S; Youssef, Noha H

    2017-01-01

    Algae encompass a wide array of photosynthetic organisms that are ubiquitously distributed in aquatic and terrestrial habitats. Algal species often bloom in aquatic ecosystems, providing a significant autochthonous carbon input to the deeper anoxic layers in stratified water bodies. In addition, various algal species have been touted as promising candidates for anaerobic biogas production from biomass. Surprisingly, in spite of its ecological and economic relevance, the microbial community involved in algal detritus turnover under anaerobic conditions remains largely unexplored. Here, we characterized the microbial communities mediating the degradation of Chlorella vulgaris (Chlorophyta), Chara sp. strain IWP1 (Charophyceae), and kelp Ascophyllum nodosum (phylum Phaeophyceae), using sediments from an anaerobic spring (Zodlteone spring, OK; ZDT), sludge from a secondary digester in a local wastewater treatment plant (Stillwater, OK; WWT), and deeper anoxic layers from a seasonally stratified lake (Grand Lake O' the Cherokees, OK; GL) as inoculum sources. Within all enrichments, the majority of algal biomass was metabolized within 13-16 weeks, and the process was accompanied by an increase in cell numbers and a decrease in community diversity. Community surveys based on the V4 region of the 16S rRNA gene identified different lineages belonging to the phyla Bacteroidetes, Proteobacteria (alpha, delta, gamma, and epsilon classes), Spirochaetes, and Firmicutes that were selectively abundant under various substrate and inoculum conditions. Within all kelp enrichments, the microbial communities structures at the conclusion of the experiment were highly similar regardless of the enrichment source, and were dominated by the genus Clostridium, or family Veillonellaceae within the Firmicutes. In all other enrichments the final microbial community was dependent on the inoculum source, rather than the type of algae utilized as substrate. Lineages enriched included the

  2. Hydrogen evolution by strictly aerobic hydrogen bacteria under anaerobic conditions.

    PubMed

    Kuhn, M; Steinbüchel, A; Schlegel, H G

    1984-08-01

    When strains and mutants of the strictly aerobic hydrogen-oxidizing bacterium Alcaligenes eutrophus are grown heterotrophically on gluconate or fructose and are subsequently exposed to anaerobic conditions in the presence of the organic substrates, molecular hydrogen is evolved. Hydrogen evolution started immediately after the suspension was flushed with nitrogen, reached maximum rates of 70 to 100 mumol of H2 per h per g of protein, and continued with slowly decreasing rates for at least 18 h. The addition of oxygen to an H2-evolving culture, as well as the addition of nitrate to cells (which had formed the dissimilatory nitrate reductase system during the preceding growth), caused immediate cessation of hydrogen evolution. Formate is not the source of H2 evolution. The rates of H2 evolution with formate as the substrate were lower than those with gluconate. The formate hydrogenlyase system was not detectable in intact cells or crude cell extracts. Rather the cytoplasmic, NAD-reducing hydrogenase is involved by catalyzing the release of excessive reducing equivalents under anaerobic conditions in the absence of suitable electron acceptors. This conclusion is based on the following experimental results. H2 is formed only by cells which had synthesized the hydrogenases during growth. Mutants lacking the membrane-bound hydrogenase were still able to evolve H2. Mutants lacking the NAD-reducing or both hydrogenases were unable to evolve H2.

  3. Biotransformation potential of phytosterols under anoxic and anaerobic conditions.

    PubMed

    Dykstra, C M; Giles, H D; Banerjee, S; Pavlostathis, S G

    2014-01-01

    The biotransformation potential of three phytosterols (campesterol, stigmasterol and β-sitosterol) under denitrifying, sulfate-reducing and fermentative/methanogenic conditions was assessed. Using a group contribution method, the standard Gibbs free energy of phytosterols was calculated and used to perform theoretical energetic calculations. The oxidation of phytosterols under aerobic, nitrate-reducing, sulfate-reducing and methanogenic conditions was determined to be energetically feasible. However, using semi-continuously fed cultures maintained at 20-22 °C over 16 weekly feeding cycles (112 days; retention time, 21 days), phytosterol removal was observed under nitrate-reducing and sulfate-reducing conditions, but not under fermentative/methanogenic conditions. Under sulfate-reducing conditions, stigmast-4-en-3-one was identified as an intermediate of phytosterol biotransformation, a reaction more likely carried out by dehydrogenases/isomerases, previously reported to act on cholesterol under both oxic and anoxic (denitrifying) conditions. Further study of the biotransformation of phytosterols under anoxic/anaerobic conditions is necessary to delineate the factors and conditions leading to enhanced phytosterol biodegradation and the development of effective biological treatment systems for the removal of phytosterols from pulp and paper wastewaters and other phytosterol-bearing waste streams.

  4. Anaerobic degradation of citrate under sulfate reducing and methanogenic conditions.

    PubMed

    Gámez, Victor M; Sierra-Alvarez, Reyes; Waltz, Rebecca J; Field, James A

    2009-07-01

    Citrate is an important component of metal processing effluents such as chemical mechanical planarization wastewaters of the semiconductor industry. Citrate can serve as an electron donor for sulfate reduction applied to promote the removal of metals, and it can also potentially be used by methanogens that coexist in anaerobic biofilms. The objective of this study was to evaluate the degradation of citrate with sulfate-reducing and methanogenic biofilms. During batch bioassays, the citrate, acetate, methane and sulfide concentrations were monitored. The results indicate that independent of the biofilm or incubation conditions used, citrate was rapidly fermented with specific rates ranging from 566 to 720 mg chemical oxygen demand (COD) consumed per gram volatile suspended solids per day. Acetate was found to be the main fermentation product of citrate degradation, which was later degraded completely under either methanogenic or sulfate reducing conditions. However, if either sulfate reduction or methanogenesis was infeasible due to specific inhibitors (2-bromoethane sulfonate), absence of sulfate or lack of adequate microorganisms in the biofilm, acetate accumulated to levels accounting for 90-100% of the citrate-COD consumed. Based on carbon balances measured in phosphate buffered bioassays, acetate, CO(2) and hydrogen are the main products of citrate fermentation, with a molar ratio of 2:2:1 per mol of citrate, respectively. In bicarbonate buffered bioassays, acetogenesis of H(2) and CO(2) increased the yield of acetate. The results taken as a whole suggest that in anaerobic biofilm systems, citrate is metabolized via the formation of acetate as the main metabolic intermediate prior to methanogenesis or sulfate reduction. Sulfate reducing consortia must be enriched to utilize acetate as an electron donor in order to utilize the majority of the electron-equivalents in citrate.

  5. Carbon Isotope Fractionation In Biotic Vs. Abiotic Anaerobic Conditions

    NASA Astrophysics Data System (ADS)

    Gebrehiwet, T. A.

    2005-12-01

    Dissimilatory metal reducing bacteria (DMRB) are thought to play an important role in the biogeochemical cycling of Fe, and nutrient elements such as C and P, in the anaerobic subsurface. The consumption of organic carbon sources (including contaminants) by these bacteria can significantly fractionate substrate C isotopes, however the effects of solution composition, electron acceptor, or electron donor on C isotopic fractionation by DMRB is at present poorly quantified. We have conducted experiments to compare the effects of bicarbonate (δ13C = -3‰) and phosphate buffers on carbon isotope fractionation by Shewanella putrefaciens strain 200R. The effects of dissolved carbonate and phosphate on δ13C values of dissolved inorganic C evolved during microbial reduction of ferric citrate (δ 13Cinitial = -25‰) were examined using sodium lactate (δ13Cinitial = -25‰) as electron donor under strict anaerobic conditions at neutral pH and 30°C, under dark and (fluorescent) light conditions. Our results suggest that bicarbonate may enhance the rate of Fe(III) reduction by S. putrefaciens, in comparison with media containing phosphate buffer but no added bicarbonate. Compared with phosphate buffered experiments, the presence of dissolved bicarbonate also resulted in a greater degree of C isotopic fractionation (ɛ=2-3‰ and ɛ=5-7‰, respectively). The effect of light on microbial Fe(III) reduction was negligible, however sterile controls showed a minor but significant quantity of carbon dioxide production in liquid media, most likely from photochemical decomposition of citrate. The abiotic experiments also showed measurable carbon isotope fractionation between the carbon dioxide produced and the organic carbon substrate which will be discussed.

  6. Potential of hydrolysis of particulate COD in extended anaerobic conditions to enhance biological phosphorous removal.

    PubMed

    Jabari, P; Yuan, Q; Oleszkiewicz, J A

    2016-11-01

    The effect of anaerobic hydrolysis of particulate COD (pCOD) on biological phosphorous removal in extended anaerobic condition was investigated through (i) sequencing batch reactors (SBR)s with anaerobic hydraulic retention time (HRT) of 0.8, 2, and 4 h; (ii) batch tests using biomass from a full scale biological nutrient removal (BNR) plant; and (iii) activated sludge modeling (BioWin 4.1 simulation). The results from long-term SBRs operation showed that phosphorus removal was correlated to the ratio of filtered COD (FCOD) to total phosphorus (TP) in the influent. Under conditions with low FCOD/TP ratio (average of 20) in the influent, extending anaerobic HRT to 4 h in the presence of pCOD did not significantly improve overall phosphorous removal. During the period with high FCOD/TP ratio (average of 37) in the influent, all SBRs removed phosphorous completely, and the long anaerobic HRT did not have negative effect on overall phosphorous removal. The batch tests also showed that pCOD at different concentration during 4 h test did not affect the rate of anaerobic phosphorus release. The rate of anaerobic hydrolysis of pCOD was significantly low and extending the anaerobic HRT was ineffective. The simulation (BioWin 4.1) of SBRs with low influent FCOD/TP ratio showed that the default kinetics of anaerobic hydrolysis in ASM2d overestimated phosphorous removal in the SBRs (high anaerobic hydrolysis of pCOD). The default anaerobic hydrolysis rate in BioWin 4.1 (ten times lower) could produce similar phosphorous removal to that in the experiment. Results showed that the current kinetics of anaerobic hydrolysis in ASM2d could lead to considerable error in predicting phosphorus removal in processes with extended anaerobic HRT. Biotechnol. Bioeng. 2016;113: 2377-2385. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  7. Biodegradability of nitrogenous compounds under anaerobic conditions and its estimation.

    PubMed

    Hongwei, Yang; Zhanpeng, Jiang; Shaoqi, Shi

    2006-02-01

    The anaerobic biodegradability of 23 nitrogenous compounds, including nitrogenous heterocyclic compounds and aliphatic amines, was tested and assessed in integration. These nitrogenous compounds were classified into readily, partially, and poorly biodegradable compounds after calculation of their integrated assessment indices (IAIs), Rules for anaerobic biodegradation of these compounds were also drawn. Stepwise regression and backpropagation artificial neural network (BP-ANN) methods were applied to establish quantitative structure-biodegradability relationships (QSBRs) based on the assessment results. In QSBR models, three molecular structure descriptors-second-order molecular connectivity index (2chi(V3)chi(v)p), and energy of the highest occupied molecular orbital (EHOMO)--were included. After analysis of the sensitivity of variables in QSBR models, it was found that the key molecular structure descriptor affecting anaerobic biodegradability of nitrogenous compounds is EHOMO, which is directly proportional to the anaerobic biodegradability of nitrogenous compounds.

  8. NATURAL BIOLOGICAL ATTENUATION OF AROMATIC HYDROCARBONS UNDER ANAEROBIC CONDITIONS

    EPA Science Inventory

    There is little consistent difference in the calculated half-lives of aromatic hydrocarbons in different anaerobic environments, but methanogenic environments might be generally the least supportive of rapid biotransformation. Toluene was usually the most rapidly biotransformed...

  9. Metabolically engineered glucose-utilizing Shewanella strains under anaerobic conditions.

    PubMed

    Choi, Donggeon; Lee, Sae Bom; Kim, Sohyun; Min, Byoungnam; Choi, In-Geol; Chang, In Seop

    2014-02-01

    Comparative genome analysis of Shewanella strains predicted that the strains metabolize preferably two- and three-carbon carbohydrates as carbon/electron source because many Shewanella genomes are deficient of the key enzymes in glycolysis (e.g., glucokinase). In addition, all Shewanella genomes are known to have only one set of genes associated with the phosphotransferase system required to uptake sugars. To engineer Shewanella strains that can utilize five- and six-carbon carbohydrates, we constructed glucose-utilizing Shewanella oneidensis MR-1 by introducing the glucose facilitator (glf; ZMO0366) and glucokinase (glk; ZMO0369) genes of Zymomonas mobilis. The engineered MR-1 strain was able to grow on glucose as a sole carbon/electron source under anaerobic conditions. The glucose affinity (Ks) and glucokinase activity in the engineered MR-1 strain were 299.46 mM and 0.259 ± 0.034 U/g proteins. The engineered strain was successfully applied to a microbial fuel cell system and exhibited current generation using glucose as the electron source. Copyright © 2013 Elsevier Ltd. All rights reserved.

  10. Performance and diversity of polyvinyl alcohol-degrading bacteria under aerobic and anaerobic conditions.

    PubMed

    Huang, Jianping; Yang, Shisu; Zhang, Siqi

    2016-11-01

    To compare the degradation performance and biodiversity of a polyvinyl alcohol-degrading microbial community under aerobic and anaerobic conditions. An anaerobic-aerobic bioreactor was operated to degrade polyvinyl alcohol (PVA) in simulated wastewater. The degradation performance of the bioreactor during sludge cultivation and the microbial communities in each reactor were compared. Both anaerobic and aerobic bioreactors demonstrated high chemical oxygen demand removal efficiencies of 87.5 and 83.6 %, respectively. Results of 16S rDNA sequencing indicated that Proteobacteria dominated in both reactors and that the microbial community structures varied significantly under different operating conditions. Both reactors obviously differed in bacterial diversity from the phyla Planctomycetes, Chlamydiae, Bacteroidetes, and Chloroflexi. Betaproteobacteria and Alphaproteobacteria dominated, respectively, in the anaerobic and aerobic reactors. The anaerobic-aerobic system is suitable for PVA wastewater treatment, and the microbial genetic analysis may serve as a reference for PVA biodegradation.

  11. Microbial degradation of lignin-derived compounds under anaerobic conditions

    SciTech Connect

    Colberg, P.J.

    1983-01-01

    Lignin is the second most abundant form of organic carbon in the biosphere. Recent laboratory studies indicate that a large fraction of polymeric lignin is incompletely degraded by aerobic lignolytic microorganisms and is subsequently released as lignin fragments of reduced molecular size. If such lignin-derived compounds become available in the anaerobic environment, they may serve as potential sources of organic carbon for organisms which release methane precursors. The methanogenic bacteria, in turn, serve as terminal members of the anaerobic food chain, and thus, limit the accumulation of organic carbon in anaerobic sinks. This thesis presents evidence to suggest that lignin-derived compounds which have molecular sizes greater than those of single-ring aromatic compounds (MW > 200) are anaerobically biodegradable to methane. This research involved development of selective enrichment cultures capable of utilizing oligolignols as sole carbon sources. Radiolabeled water-soluble catabolites, released during aerobic lignin degradation by the white rot fungus Phanerochaete chrysosporium, were subjected to anaerobic degradation. The second phase of work involved capillary gas chromatographic analyses of enrichment cultures fed a /sup 14/C-labeled, lignin-derived substrate of average molecular weight 600. 2-Bromoethanesulfonic acid was used to inhibit methane formation and enhance buildup of metabolic intermediates, resulting in the accumulation of volatile fatty acids, phenylacetate, benzoate, catechol, 3-phenyl-propionate, vanillin, syringic acid, vanillic acid, ferulic acid, and caffeic acid. A conceptual model for the anaerobic degradation of two- and three-ring lignin fragments is proposed which overlaps both the ferulate and benzoate degradation pathways at the level of single-ring aromatic compounds.

  12. Metabolism of aniline under different anaerobic electron-accepting and nutritional conditions

    SciTech Connect

    De, M.A.; O'Connor, O.A.; Kosson, D.S. . Dept. of Chemical and Biochemical Engineering)

    1994-02-01

    The biodegradability of aniline was evaluated under two different anaerobic conditions, denitrifying and methanogenic. In addition, under denitrifying conditions, the influence of bicarbonate was studied. Anaerobic sewage digester sludge and estuarine sediment were used as heterogeneous sources of bacteria. Under anaerobic denitrifying conditions amended with bicarbonate, aniline was completely mineralized to CO[sub 2] and N[sub 2]. After an initial lag period, N[sub 2] recoveries of 74 and 100% were obtained for sludge and sediment cultures, respectively. Under anaerobic denitrifying conditions with no bicarbonate, aniline depletion was observed; however, stoichiometric quantities of N[sub 2] were not produced from mineralization and were in fact inhibited below background controls. Under methanogenic conditions, aniline concentration remained unchanged for > 31 weeks. A metabolite of aniline, 4-hydroxybenzoate, was detected in bicarbonate-amended denitrifying cultures.

  13. ANAEROBIC BIODEGRADATION OF ALKYLBENZENES IN LABORATORY MICROCOSMS REPRESENTING AMBIENT CONDITIONS

    EPA Science Inventory

    A microcosm study was performed to document the anaerobic biodegradation of benzene, toluene, ethylbenzene, m- xylene, and/or o-xylene in petroleum-contaminated aquifer sediment from sites in Michigan (MI) and North Carolina (NC) and relate the results to previous field investiga...

  14. ANAEROBIC BIODEGRADATION OF ALKYLBENZENES IN LABORATORY MICROCOSMS REPRESENTING AMBIENT CONDITIONS

    EPA Science Inventory

    A microcosm study was performed to document the anaerobic biodegradation of benzene, toluene, ethylbenzene, m- xylene, and/or o-xylene in petroleum-contaminated aquifer sediment from sites in Michigan (MI) and North Carolina (NC) and relate the results to previous field investiga...

  15. Candidatus Accumulibacter phosphatis clades enriched under cyclic anaerobic and microaerobic conditions simultaneously use different electron acceptors

    EPA Science Inventory

    Lab- and pilot-scale simultaneous nitrification, denitrification and phosphorus removal-sequencing batch reactors were operated under cyclic anaerobic and micro-aerobic conditions. The use of oxygen, nitrite, and nitrate as electron acceptors by Candidatus Accumulibacter phosphat...

  16. MICROBIAL DEGRADATION OF NITROGEN, OXYGEN AND SULFUR HETEROCYCLIC COMPOUNDS UNDER ANAEROBIC CONDITIONS: STUDIES WITH AQUIFER SAMPLES

    EPA Science Inventory

    The potential for anaerobic biodegradation of 12 heterocyclic model compounds was studied. Nine of the model compounds were biotransformed in aquifer slurries under sulfate-reducing or methanogenic conditions. The nitrogen and oxygen heterocyclic compounds were more susceptible t...

  17. MICROBIAL DEGRADATION OF NITROGEN, OXYGEN AND SULFUR HETEROCYCLIC COMPOUNDS UNDER ANAEROBIC CONDITIONS: STUDIES WITH AQUIFER SAMPLES

    EPA Science Inventory

    The potential for anaerobic biodegradation of 12 heterocyclic model compounds was studied. Nine of the model compounds were biotransformed in aquifer slurries under sulfate-reducing or methanogenic conditions. The nitrogen and oxygen heterocyclic compounds were more susceptible t...

  18. Candidatus Accumulibacter phosphatis clades enriched under cyclic anaerobic and microaerobic conditions simultaneously use different electron acceptors

    EPA Science Inventory

    Lab- and pilot-scale simultaneous nitrification, denitrification and phosphorus removal-sequencing batch reactors were operated under cyclic anaerobic and micro-aerobic conditions. The use of oxygen, nitrite, and nitrate as electron acceptors by Candidatus Accumulibacter phosphat...

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

    NASA Astrophysics Data System (ADS)

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

    2010-03-01

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

  20. Reduction of Nitrated Diphenylamine Derivatives under Anaerobic Conditions

    PubMed Central

    Drzyzga, O.; Schmidt, A.; Blotevogel, K.

    1995-01-01

    2-Nitrodiphenylamine, 4-nitrodiphenylamine, and 2,4-dinitrodiphenylamine were anaerobically metabolized in sediment-water batch enrichments inoculated with mud from the German North Sea coast. The first intermediate in 2,4-dinitrodiphenylamine degradation was 2-amino-4-nitrodiphenylamine, which appeared in large (nearly stoichiometric) amounts before being completely reduced to 2,4-diaminodiphenylamine. Of the second theoretically expected metabolite, 4-amino-2-nitrodiphenylamine, only traces were detected by gas chromatographic-mass spectrometric analysis in highly concentrated extracts. In addition, low levels of 4-nitrodiphenylamine, which may be the product of ortho deamination of intermediately produced 2-amino-4-nitrodiphenylamine, were observed. 2-Nitrodiphenylamine and 4-nitrodiphenylamine were primarily reduced to 2-aminodiphenylamine and 4-aminodiphenylamine, respectively. Diphenylamine was never detected in any experiment as a theoretically possible intermediate. Results from studies with dense cell suspensions of anaerobic, aromatic-compound-mineralizing bacteria confirmed the transformation reactions, which were carried out by microorganisms indigenous to the anaerobic coastal water sediment. PMID:16535118

  1. Directed evolution of a cellodextrin transporter for improved biofuel production under anaerobic conditions in Saccharomyces cerevisiae.

    PubMed

    Lian, Jiazhang; Li, Yanglin; HamediRad, Mohammad; Zhao, Huimin

    2014-08-01

    Introduction of a cellobiose utilization pathway consisting of a cellodextrin transporter and a β-glucosidase into Saccharomyces cerevisiae enables co-fermentation of cellobiose and xylose. Cellodextrin transporter 1 (CDT1) from Neurospora crassa has been established as an effective transporter for the engineered cellobiose utilization pathways. However, cellodextrin transporter 2 (CDT2) from the same species is a facilitator and has the potential to be more efficient than CDT1 under anaerobic conditions due to its energetic benefits. Currently, CDT2 has a very low activity and is considered rate-limiting in cellobiose fermentation. Here, we report the directed evolution of CDT2 with an increased cellobiose uptake activity, which results in improved cellobiose fermentation under anaerobic conditions. After three rounds of directed evolution, the cellobiose uptake activity of CDT2 was increased by 2.2-fold, which resulted from both increased specific activity and transporter expression level. Using high cell density fermentation under anaerobic conditions, the evolved mutant conferred 4.0- and 4.4-fold increase in the cellobiose consumption rate and ethanol productivity, respectively. In addition, although the cellobiose uptake activity was still lower than that of CDT1, the engineered CDT2 showed significantly improved cellobiose consumption and ethanol production under anaerobic conditions, representing the energetic benefits of a sugar facilitator for anaerobic cellobiose fermentation. This study demonstrated that anaerobic biofuel production could be significantly improved via directed evolution of a sugar transporter protein in yeast.

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

    PubMed Central

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

    1996-01-01

    Nitrous oxide can be a harmful by-product in nitrogen removal from wastewater. Since wastewater treatment systems operate under different aeration regimens, the influence of different oxygen concentrations and oxygen fluctuations on denitrification was studied. Continuous cultures of Alcaligenes faecalis TUD produced N2O under anaerobic as well as aerobic conditions. Below a dissolved oxygen concentration of 5% air saturation, the relatively highest N2O production was observed. Under these conditions, significant activities of nitrite reductase could be measured. After transition from aerobic to anaerobic conditions, there was insufficient nitrite reductase present to sustain growth and the culture began to wash out. After 20 h, nitrite reductase became detectable and the culture started to recover. Nitrous oxide reductase became measurable only after 27 h, suggesting sequential induction of the denitrification reductases, causing the transient accumulation of N2O. After transition from anaerobic conditions to aerobic conditions, nitrite reduction continued (at a lower rate) for several hours. N2O reduction appeared to stop immediately after the switch, indicating inhibition of nitrous oxide reductase, resulting in high N2O emissions (maximum, 1.4 mmol liter-1 h-1). The nitrite reductase was not inactivated by oxygen, but its synthesis was repressed. A half-life of 16 to 22 h for nitrite reductase under these conditions was calculated. In a dynamic aerobic-anaerobic culture of A. faecalis, a semisteady state in which most of the N2O production took place after the transition from anaerobic to aerobic conditions was obtained. The nitrite consumption rate in this culture was equal to that in an anaerobic culture (0.95 and 0.92 mmol liter-1 h-1, respectively), but the production of N2O was higher in the dynamic culture (28 and 26% of nitrite consumption, respectively). PMID:8779582

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

    PubMed Central

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

    2016-01-01

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

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

    PubMed

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

    2016-01-01

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

  5. Anaerobic Oxidation of [1,2-14C]Dichloroethene under Mn(IV)-Reducing Conditions

    PubMed Central

    Bradley, Paul M.; Landmeyer, James E.; Dinicola, Richard S.

    1998-01-01

    Anaerobic oxidation of [1,2-14C]dichloroethene to 14CO2 under Mn(IV)-reducing conditions was demonstrated. The results indicate that oxidative degradation of partially chlorinated solvents like dichloroethene can be significant even under anoxic conditions and demonstrate the potential importance of Mn(IV) reduction for remediation of chlorinated groundwater contaminants. PMID:16349554

  6. Anaerobic oxidation of [1,2-14C]Dichloroethene under Mn(IV)-reducing conditions

    USGS Publications Warehouse

    Bradley, Paul M.; Landmeyer, James E.; Dinicola, Richard S.

    1998-01-01

    Anaerobic oxidation of [1,2-14C]dichloroethene to14CO2 under Mn(IV)-reducing conditions was demonstrated. The results indicate that oxidative degradation of partially chlorinated solvents like dichloroethene can be significant even under anoxic conditions and demonstrate the potential importance of Mn(IV) reduction for remediation of chlorinated groundwater contaminants.

  7. Succinate and Lactate Production from Euglena gracilis during Dark, Anaerobic Conditions

    PubMed Central

    Tomita, Yuko; Yoshioka, Kazumasa; Iijima, Hiroko; Nakashima, Ayaka; Iwata, Osamu; Suzuki, Kengo; Hasunuma, Tomohisa; Kondo, Akihiko; Hirai, Masami Yokota; Osanai, Takashi

    2016-01-01

    Euglena gracilis is a eukaryotic, unicellular phytoflagellate that has been widely studied in basic science and applied science. Under dark, anaerobic conditions, the cells of E. gracilis produce a wax ester that can be converted into biofuel. Here, we demonstrate that under dark, anaerobic conditions, E. gracilis excretes organic acids, such as succinate and lactate, which are bulk chemicals used in the production of bioplastics. The levels of succinate were altered by changes in the medium and temperature during dark, anaerobic incubation. Succinate production was enhanced when cells were incubated in CM medium in the presence of NaHCO3. Excretion of lactate was minimal in the absence of external carbon sources, but lactate was produced in the presence of glucose during dark, anaerobic incubation. E. gracilis predominantly produced L-lactate; however, the percentage of D-lactate increased to 28.4% in CM medium at 30°C. Finally, we used a commercial strain of E. gracilis for succinate production and found that nitrogen-starved cells, incubated under dark, anaerobic conditions, produced 869.6 mg/L succinate over a 3-day incubation period, which was 70-fold higher than the amount produced by nitrogen-replete cells. This is the first study to demonstrate organic acid excretion by E. gracilis cells and to reveal novel aspects of primary carbon metabolism in this organism. PMID:28066371

  8. Succinate and Lactate Production from Euglena gracilis during Dark, Anaerobic Conditions.

    PubMed

    Tomita, Yuko; Yoshioka, Kazumasa; Iijima, Hiroko; Nakashima, Ayaka; Iwata, Osamu; Suzuki, Kengo; Hasunuma, Tomohisa; Kondo, Akihiko; Hirai, Masami Yokota; Osanai, Takashi

    2016-01-01

    Euglena gracilis is a eukaryotic, unicellular phytoflagellate that has been widely studied in basic science and applied science. Under dark, anaerobic conditions, the cells of E. gracilis produce a wax ester that can be converted into biofuel. Here, we demonstrate that under dark, anaerobic conditions, E. gracilis excretes organic acids, such as succinate and lactate, which are bulk chemicals used in the production of bioplastics. The levels of succinate were altered by changes in the medium and temperature during dark, anaerobic incubation. Succinate production was enhanced when cells were incubated in CM medium in the presence of NaHCO3. Excretion of lactate was minimal in the absence of external carbon sources, but lactate was produced in the presence of glucose during dark, anaerobic incubation. E. gracilis predominantly produced L-lactate; however, the percentage of D-lactate increased to 28.4% in CM medium at 30°C. Finally, we used a commercial strain of E. gracilis for succinate production and found that nitrogen-starved cells, incubated under dark, anaerobic conditions, produced 869.6 mg/L succinate over a 3-day incubation period, which was 70-fold higher than the amount produced by nitrogen-replete cells. This is the first study to demonstrate organic acid excretion by E. gracilis cells and to reveal novel aspects of primary carbon metabolism in this organism.

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

    SciTech Connect

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

    1996-07-01

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

  10. Heterologous production of Pseudomonas aeruginosa rhamnolipid under anaerobic conditions for microbial enhanced oil recovery.

    PubMed

    Zhao, F; Shi, R; Zhao, J; Li, G; Bai, X; Han, S; Zhang, Y

    2015-02-01

    The ex situ application of rhamnolipid to enhance oil recovery is costly and complex in terms of rhamnolipid production and transportation, while in situ production of rhamnolipid is restricted by the oxygen-deficient environments of oil reservoirs. To overcome the oxygen-limiting conditions and to circumvent the complex regulation of rhamnolipid biosynthesis in Pseudomonas aeruginosa, an engineered strain Pseudomonas stutzeri Rhl was constructed for heterologous production of rhamnolipid under anaerobic conditions. The rhlABRI genes for rhamnolipid biosynthesis were cloned into a facultative anaerobic strain Ps. stutzeri DQ1 to construct the engineered strain Rhl. Anaerobic production of rhamnolipid was confirmed by thin layer chromatography and Fourier transform infrared analysis. Rhamnolipid product reduced the air-water surface tension to 30.3 mN m(-1) and the oil-water interfacial tension to 0.169 mN m(-1). Rhl produced rhamnolipid of 1.61 g l(-1) using glycerol as the carbon source. Rhl anaerobic culture emulsified crude oil up to EI24 ≈ 74. An extra 9.8% of original crude oil was displaced by Rhl in the core flooding test. Strain Rhl achieved anaerobic production of rhamnolipid and worked well for enhanced oil recovery in the core flooding model. The rhamnolipid produced by Rhl was similar to that of the donor strain SQ6. This is the first study to achieve anaerobic and heterologous production of rhamnolipid. Results demonstrated the potential feasibility of Rhl as a promising strain to enhance oil recovery through anaerobic production of rhamnolipid. © 2014 The Society for Applied Microbiology.

  11. Anaerobic degradation and dehalogenation of chlorosalicylates and salicylate under four reducing conditions.

    PubMed

    Milligan, P W; Häggblom, M M

    2001-01-01

    The anaerobic biodegradability and transformation of the mono-and dichlorinated salicylates (2-hydroxybenzoates) was examined under denitrifying, Fe (III) reducing, sulfate reducing and methanogenic conditions. 3,6-Dichlorosalicylate and 6-chlorosalicylate are anaerobic microbial metabolites of dicamba, a widely used herbicide. Anaerobic microcosms were established with dicamba treated soil from Wyoming, and golf course drainage stream sediments from New Jersey, which were each spiked with salicylate, 3,6-dichlorosalicylate or one of the four monochlorosalicylate isomers. Salicylate was degraded under denitrifying, sulfidogenic and methanogenic conditions. In methanogenic enrichments 5-chlorosalicylate and 3-chlorosalicylate were reductively dehalogenated to salicylate which was then utilized. Dehalogenation of monochlorinated salicylates to salicylate was also observed in denitrifying chlorosalicylate degrading cultures. The study revealed that the position of the chlorine substituent as well as the predominant electron accepting process affect the rate and extent of chlorosalicylate degradation in anoxic environments.

  12. Monoaromatic hydrocarbon transformation under anaerobic conditions at Seal Beach, California: Laboratory studies

    SciTech Connect

    Ball, H.A.; Reinhard, M.

    1996-02-01

    Anaerobic biotransformation of several aromatic hydrocarbons found in gasoline including benzene, toluene, ethylbenzene, m-xylene, p-xylene, and o-xylene (BTEX) was studied in batch anaerobic laboratory microcosms. Aquifer sediment and ground water were obtained from the site of a historic gasoline spill at Seal Beach, California. Sulfate is present in the site ground water at 80 mg/L, and sulfate-reducing activity appears to be the dominant intrinsic BTEX bioremediation process where nitrate is absent. In the laboratory, the microcosms were set up with different electron acceptors (sulfate and nitrate) in site ground water and various defined anaerobic media to estimate intrinsic biodegradation rates and to suggest conditions under which anaerobic bioremediation could be enhanced. In unamended microcosms, anaerobic biotransformation of toluene and m + p-xylene occurred at a rate of 7.2 and 4.1 {micro}g/liter hr, respectively, with sulfate as the apparent electron acceptor. Addition of nitrate stimulated nitrate-reducing conditions and increased rates of toluene and m + p-xylene biotransformation to 30.1 and 5.4 {micro}g/liter hr, respectively. The catabolic substrate range was altered to include ethylbenzene in the nitrate-amended microcosms, suggesting an apparent preferential use of different BTEX compounds depending on the electron acceptor available. Under all the conditions studied, more than twice the amount of nitrate or sulfate was used than could be accounted for by the observed BTEX degradation. The results of these experiments indicate that indigenous microorganisms from the Seal Beach aquifer have significant capability to degrade BTEX hydrocarbons and that intrinsic processes in the Seal Beach aquifer may remediate a portion of the hydrocarbon contamination in situ without intervention. However, the data also suggest that intervention by nitrate addition would enhance the rate and extent of anaerobic BTEX biotransformation.

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

    PubMed

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

    2016-04-01

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

  14. Anaerobic Biodegradation of Soybean Biodiesel and Diesel Blends under Methanogenic Conditions

    EPA Science Inventory

    Biotransformation of soybean biodiesel and the inhibitory effect of petrodiesel were studied under methanogenic conditions. Biodiesel removal efficiency of more than 95% was achieved in a chemostat with influent biodiesel concentrations up to 2.45 g/L. The kinetics of anaerobic...

  15. Proton motive force generation from stored polymers for the uptake of acetate under anaerobic conditions.

    PubMed

    Saunders, Aaron M; Mabbett, Amanda N; McEwan, Alastair G; Blackall, Linda L

    2007-09-01

    The bacteria facilitating enhanced biological phosphorus removal gain a selective advantage from intracellularly stored polymer-driven substrate uptake under anaerobic conditions during sequential anaerobic : aerobic cycling. Mechanisms for these unusual membrane transport processes were proposed and experimentally validated using selective inhibitors and highly-enriched cultures of a polyphosphate-accumulating organism, Accumulibacter, and a glycogen-accumulating organism, Competibacter. Acetate uptake by both Accumulibacter and Competibacter was driven by a proton motive force (PMF). Stored polymers were used to generate the PMF -Accumulibacter used phosphate efflux through the Pit transporter, while Competibacter generated a PMF by proton efflux through the ATPase and fumarate reductase in the reductive TCA cycle.

  16. Isolation and Characterization of an Enterobacter cloacae Strain That Reduces Hexavalent Chromium under Anaerobic Conditions

    PubMed Central

    Wang, Pi-Chao; Mori, Tsukasa; Komori, Kohya; Sasatsu, Masanori; Toda, Kiyoshi; Ohtake, Hisao

    1989-01-01

    An Enterobacter cloacae strain (HO1) capable of reducing hexavalent chromium (chromate) was isolated from activated sludge. This bacterium was resistant to chromate under both aerobic and anaerobic conditions. Only the anaerobic culture of the E. cloacae isolate showed chromate reduction. In the anaerobic culture, yellow turned white with chromate and the turbidity increased as the reduction proceeded, suggesting that insoluble chromium hydroxide was formed. E. cloacae is likely to utilize toxic chromate as an electron acceptor anaerobically because (i) the anaerobic growth of E. cloacae HO1 accompanied the decrease of toxic chromate in culture medium, (ii) the chromate-reducing activity was rapidly inhibited by oxygen, and (iii) the reduction occurred more rapidly in glycerol- or acetate-grown cells than in glucose-grown cells. The chromate reduction in E. cloacae HO1 was observed at pH 6.0 to 8.5 (optimum pH, 7.0) and at 10 to 40°C (optimum, 30°C). PMID:16347962

  17. Rapid detection of a gfp-marked Enterobacter aerogenes under anaerobic conditions by aerobic fluorescence recovery.

    PubMed

    Zhang, Chong; Xing, Xin-Hui; Lou, Kai

    2005-08-15

    A gfp- and kanamycin-resistance gene-containing plasmid pUCGK was successfully constructed and transformed into Enterobacter aerogenes to develop a rapid GFP-based method for quantifying the bacterial concentration under anaerobic conditions for production of biohydrogen. Since the use of GFP as a molecular reporter is restricted by its requirement for oxygen in the development of the fluorophore, fluorescence detection for the fluorescent E. aerogenes grown anaerobically for hydrogen production was performed by developing a method of aerobic fluorescence recovery (AFR) of the anaerobically expressed GFP. By using this AFR method, rapid and non-disruptive cell quantification of E. aerogenes by fluorescence density was achieved for analyzing the hydrogen production process.

  18. Biodegradability of biodegradable/degradable plastic materials under aerobic and anaerobic conditions.

    PubMed

    Mohee, R; Unmar, G D; Mudhoo, A; Khadoo, P

    2008-01-01

    A study was conducted on two types of plastic materials, Mater-Bi Novamont (MB) and Environmental Product Inc. (EPI), to assess their biodegradability under aerobic and anaerobic conditions. For aerobic conditions, organic fractions of municipal solid wastes were composted. For the anaerobic process, anaerobic inoculum from a wastewater treatment plant was used. Cellulose filter papers (CFP) were used as a positive control for both mediums. The composting process was monitored in terms of temperature, moisture and volatile solids and the biodegradation of the samples were monitored in terms of mass loss. Monitoring results showed a biodegradation of 27.1% on a dry basis for MB plastic within a period of 72 days of composting. Biodegradability under an anaerobic environment was monitored in terms of biogas production. A cumulative methane gas production of 245 ml was obtained for MB, which showed good degradation as compared to CFP (246.8 ml). However, EPI plastic showed a cumulative methane value of 7.6 ml for a period of 32 days, which was close to the blank (4.0 ml). The EPI plastic did not biodegrade under either condition. The cumulative carbon dioxide evolution after 32 days was as follows: CFP 4.406 cm3, MB 2.198 cm3 and EPI 1.328 cm3. The cumulative level of CO2 varying with time fitted sigmoid type curves with R2 values of 0.996, 0.996 and 0.995 for CFP, MB and EPI, respectively.

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

  20. Effects of reservoir anaerobic, reducing conditions on surfactant retention in chemical flooding

    SciTech Connect

    Wang, F.H.L. )

    1993-05-01

    Surfactant retentions observed in four microemulsion-flooding pilot tests at the Loudon field were substantially lower than predicted from conventional laboratory coreflood experiments. This paper presents research results that explain this discrepancy. The oil reservoir was in an anaerobic, reducing conditions, whereas laboratory corefloods were normally conducted under aerobic, oxidizing conditions. The difference in redox condition was shown to have a serious effect on surfactant retention. Laboratory corefloods conducted under reservoir-like, anaerobic, reducing conditions gave surfactant retention results significantly closer to those observed in field tests. The effect of redox conditions on surfactant adsorption was substantiated further by results from static adsorption experiments with various clay types. Exposure of preserved cores from a reduced reservoir to aerobic conditions can cause high surfactant retention in corefloods. Methods were developed to restore such oxygen-contaminated core material to its original, anaerobic, reduced state. These coreflood procedures simulate actual reservoir conditions better and give meaningful surfactant-retention results for process design optimization.

  1. Products of Leishmania braziliensis glucose catabolism: release of D-lactate and, under anaerobic conditions, glycerol

    SciTech Connect

    Darling, T.N.; Davis, D.G.; London, R.E.; Blum, J.J.

    1987-10-01

    Leishmania braziliensis panamensis promastigotes were incubated with glucose as the sole carbon source. About one-fifth of the glucose consumed under aerobic conditions was oxidized to CO/sub 2/. Nuclear magnetic resonance studies with (1-/sup 13/C)glucose showed that the other products released were succinate, acetate, alanine, pyruvate, and lactate. Under anaerobic conditions, lactate output increased, glycerol became a major product, and, surprisingly, glucose consumption decreased. Enzymatic assays showed that the lactate formed was D(-)-lactate. The release of alanine during incubation with glucose as the sole carbon source suggested that appreciable proteolysis occurred, consistent with our observation that a large amount of ammonia was released under these conditions. The discoveries that D-lactate is a product of L. braziliensis glucose catabolism, that glycerol is produced under anaerobic conditions, and that the cells exhibit a reverse Pasteur effect open the way for detailed studies of the pathways of glucose metabolism and their regulation in this organism.

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

    PubMed

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

    2013-07-01

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

  3. Cyanide toxicity in hepatocytes under aerobic and anaerobic conditions.

    PubMed

    Aw, T Y; Jones, D P

    1989-09-01

    The effect of cyanide on cell viability and mitochondrial function was studied in hepatocytes exposed to air or argon. Cells were more susceptible to cyanide toxicity under air than under argon. Analysis of the disposition of cyanide showed that the difference in susceptibility to KCN was not due to O2-dependent differences in cyanide metabolism or elimination. Studies of mitochondrial function revealed that cyanide under aerobic conditions resulted in substantial swelling of the mitochondria, which corresponded to a matrix loading of phosphate. In addition, cyanide caused a loss of the mitochondrial protonmotive force. This was in contrast to the results for cells exposed to 30 min of anoxia alone in which there was no loss of mitochondrial delta pH, no detectable change in mitochondrial volume, and little matrix loading of phosphate. These results show that at least some of the protective mechanisms elicited by anoxia (B. S. Andersson, T. Y. Aw, and D. P. Jones. Am. J. Physiol. 252 (Cell Physiol. 21): C349-C355, 1987) are not elicited by cyanide alone. Thus cyanide under aerobic conditions does not provide a completely valid model for simple anoxia. Moreover, the results suggest that the molecular sensor necessary to signal suppression of metabolic and transport functions during neahypoxia is dependent on O2 and is neither stimulated nor antagonized by KCN.

  4. Dissipation of [(14)C]acetochlor herbicide under anaerobic aquatic conditions in flooded soil microcosms.

    PubMed

    Loor-Vela, Sandra X; Crawford Simmons, Jennifer J; Simmons, F William; Raskin, Lutgarde

    2003-11-05

    Acetochlor degradation was studied under anaerobic conditions representative of conditions in flooded soils. Soil-water microcosms were prepared with a saturated Drummer clay loam and made anaerobic by either glucose pretreatment or N(2) sparging. Sparged microcosms consisted of sulfate-amended, unamended, and gamma-irradiated microcosms. The microcosms were sampled in triplicate at predetermined time intervals during a 371 day incubation period. Volatile, aqueous, extractable, and bound (unextractable) (14)C residues were quantified with liquid scintillation counting and characterized using high-performance liquid radiochromatography (HPLRC) and soil combustion. SO(4)(2)(-), Fe(II), CH(4), and pH were monitored. Complete anaerobic degradation of [(14)C]acetochlor was observed in all viable treatments. The time observed for 50% acetochlor disappearance (DT(50)) was 10 days for iron-reducing and sulfate-reducing conditions (sulfate-amended), 15 days for iron-reducing conditions (unamended), and 16 days for methanogenic conditions (glucose-pretreated). Acetochlor remained after 371 days in the gamma-irradiated microcosms, and metabolites were observed. [(14)C]Metabolites were detected throughout the study. Formation of one of the metabolites correlated with Fe(II) formation (r(2)(), 0.83). A significant portion of the (14)C activity was eventually incorporated into soil-bound residue (30-50% of applied acetochlor) in all treatments.

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

    PubMed

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

    2014-10-01

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

  6. Stability of antibiotics under growth conditions for thermophilic anaerobes

    SciTech Connect

    Peteranderl, R.; Shotts, E.B. Jr.; Wiegel, J. )

    1990-06-01

    It was shown that the inhibitory effect of kanamycin and streptomycin in a growing culture of Clostridium thermohydrosulfuricum JW 102 is of limited duration. To screen a large number of antibiotics, their stability during incubation under the growth conditions of thermophilic clostridia was determined at 72 and 50C by using a 0.2% yeast extract-amended prereduced mineral medium with a pH of 7.3 or 5.0. Half-lives were determined in a modified MIC test with Escherichia coli, Staphylococcus aureus, and Bacillus megaterium as indicator strains. All compounds tested were similar at the two temperatures or more stable at 50 than at 72C. The half-life (t{sub 1/2}) at pH 7.3 and 72C ranged from 3.3 h (k = 7.26 day{sup {minus}1}, where k (degradation constant) = 1/t{sub 1/2}) for ampicillin to no detectable loss of activity for kanamycin, neomycin, and other antibiotics. Apparently some compounds became more potent during incubation. A change to pH 5.0 caused some compounds to become more labile to become more stable than at pH 7.3.

  7. CO2 -dependent metabolic modulation in red blood cells stored under anaerobic conditions.

    PubMed

    Dumont, Larry J; D'Alessandro, Angelo; Szczepiorkowski, Zbigniew M; Yoshida, Tatsuro

    2016-02-01

    Anaerobic red blood cell (RBC) storage reduces oxidative damage, maintains adenosine triphosphate (ATP) and 2,3-diphosphoglycerate (DPG) levels, and has superior 24-hour recovery at 6 weeks compared to standard storage. This study will determine if removal of CO2 during O2 depletion by gas exchange may affect RBCs during anaerobic storage. This is a matched three-arm study (n = 14): control, O2 and CO2 depleted with Ar (AN), and O2 depleted with 95%Ar/5%CO2 (AN[CO2 ]). RBCs in additives AS-3 or OFAS-3 were evenly divided into three bags, and anaerobic conditions were established by gas exchange. Bags were stored at 1 to 6°C in closed chambers under anaerobic conditions or ambient air, sampled weekly for up to 9 weeks for a panel of in vitro tests. A full metabolomics screening was conducted for the first 4 weeks of storage. Purging with Ar (AN) results in alkalization of the RBC and increased glucose consumption. The addition of 5% CO2 to the purging gas prevented CO2 loss with an equivalent starting and final pH and lactate to control bags (p > 0.5, Days 0-21). ATP levels are higher in AN[CO2 ] (p < 0.0001). DPG was maintained beyond 2 weeks in the AN arm (p < 0.0001). Surprisingly, DPG was lost at the same rate in both control and AN[CO2 ] arms (p = 0.6). Maintenance of ATP in the AN[CO2 ] arm demonstrates that ATP production is not solely a function of the pH effect on glycolysis. CO2 in anaerobic storage prevented the maintenance of DPG, and DPG production appears to be pH dependent. CO2 as well as O2 depletion provides metabolic advantage for stored RBCs. © 2015 AABB.

  8. Microbial community dynamics in batch high-solid anaerobic digestion of food waste under mesophilic conditions.

    PubMed

    Yi, Jing; Dong, Bin; Xue, Yonggang; Li, Ning; Gao, Peng; Zhao, Yuxin; Dai, Lingling; Dai, Xiaohu

    2014-02-28

    Microbial community shifts, associated with performance data, were investigated in an anaerobic batch digester treating high-solid food waste under mesophilic conditions using, a combination of molecular techniques and chemical analysis methods. The batch process was successfully operated with an organic removal efficiency of 44.5% associated with a biogas yield of 0.82 L/g VSremoval. Microbial community structures were examined by denaturing gel gradient electrophoresis. Clostridium and Symbiobacterium organisms were suggested to be mainly responsible for the organic matter catabolism in hydrolysis and acidogenesis reactions. The dynamics of archaeal and methanogenic populations were monitored using real-time PCR targeting 16S rRNA genes. Methanosarcina was the predominant methanogen, suggesting that the methanogenesis took place mainly via an aceticlastic pathway. Hydrogenotrophic methanogens were also supported in high-solid anaerobic digestion of food waste through syntrophism with syntrophic bacterium. Microbial community shifts showed good agreement with the performance parameters in anaerobic digestion, implying the possibility of diagnosing a high-solid anaerobic digestion process by monitoring microbial community shifts. On the other hand, the batch results could be relevant to the start-up period of a continuous system and could also provide useful information to set up a continuous operation.

  9. Physiological requirements for growth and competitiveness of Dekkera bruxellensis under oxygen-limited or anaerobic conditions.

    PubMed

    Blomqvist, Johanna; Nogué, Violeta Sànchez; Gorwa-Grauslund, Marie; Passoth, Volkmar

    2012-07-01

    The effect of glucose and oxygen limitation on the growth and fermentation performances of Dekkera bruxellensis was investigated in order to understand which factors favour its propagation in ethanol or wine plants. Although D. bruxellensis has been described as a facultative anaerobe, no growth was observed in mineral medium under complete anaerobiosis while growth was retarded under severe oxygen limitation. In a continuous culture with no gas inflow, glucose was not completely consumed, most probably due to oxygen limitation. When an air/nitrogen mixture (O(2)-content ca. 5%) was sparged to the culture, growth became glucose-limited. In co-cultivations with Saccharomyces cerevisiae, ethanol yields/g consumed sugar were not affected by the co-cultures as compared to the pure cultures. However, different population responses were observed in both systems. In oxygen-limited cultivation, glucose was depleted within 24 h after challenging with S. cerevisiae and both yeast populations were maintained at a stable level. In contrast, the S. cerevisiae population constantly decreased to about 1% of its initial cell number in the sparged glucose-limited fermentation, whereas the D. bruxellensis population remained constant. To identify the requirements of D. bruxellensis for anaerobic growth, the yeast was cultivated in several nitrogen sources and with the addition of amino acids. Yeast extract and most of the supplied amino acids supported anaerobic growth, which points towards a higher nutrient demand for D. bruxellensis compared to S. cerevisiae in anaerobic conditions. Copyright © 2012 John Wiley & Sons, Ltd.

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

    USGS Publications Warehouse

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

    2002-01-01

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

  11. Biodegradation of soluble aromatic compounds of jet fuel under anaerobic conditions: laboratory batch experiments.

    PubMed

    Zheng, Z; Breedveld, G; Aagaard, P

    2001-11-01

    Laboratory batch experiments were performed with contaminated aquifer sediments and four soluble aromatic components of jet fuel to assess their biodegradation under anaerobic conditions. The biodegradation of four aromatic compounds, toluene, o-xylene, 1,2,4-trimethylbenzene (TMB), and naphthalene, separately or together, was investigated under strictly anaerobic conditions in the dark for a period of 160 days. Of the aromatic compounds, toluene and o-xylene were degraded both as a single substrate and in a mixture with the other aromatic compounds, while TMB was not biodegraded as a single substrate, but was biodegraded in the presence of the other aromatic hydrocarbons. Substrate interaction is thus significant in the biodegradation of TMB. Biodegradation of naphthalene was not observed, either as a single substrate or in a mixture of other aromatic hydrocarbons. Although redox conditions were dominated by iron reduction, a clear relation between degradation and sulfate reduction was observed. Methanogenesis took place during the later stages of incubation. However, the large background of Fe(II) masked the increase of Fe(II) concentration due to iron reduction. Thus, although microbial reduction of Fe(III) is an important process, the evidence is not conclusive. Our results have shown that a better understanding of the degradation of complex mixtures of hydrocarbons under anaerobic conditions is important in the application of natural attenuation as a remedial method for soil and groundwater contamination.

  12. Anionic metabolite biosynthesis enhanced by potassium under dark, anaerobic conditions in cyanobacteria

    PubMed Central

    Ueda, Sakiko; Kawamura, Yuhki; Iijima, Hiroko; Nakajima, Mitsuharu; Shirai, Tomokazu; Okamoto, Mami; Kondo, Akihiko; Hirai, Masami Yokota; Osanai, Takashi

    2016-01-01

    Potassium (K+) is an essential macronutrient for all living organisms including cyanobacteria. Cyanobacteria are a group of bacteria performing oxygenic photosynthesis, widely studied in basic and applied sciences. The primary metabolism of the unicellular cyanobacterium Synechocystis sp. PCC 6803 is altered by environmental conditions, and it excretes organic acids and hydrogen under dark, anaerobic conditions. Here we demonstrated that K+ widely changes the primary carbon metabolism of this cyanobacterium. Succinate and lactate excretion from the cells incubated under dark, anaerobic conditions was enhanced in the presence of K+, while hydrogen production was repressed. The addition of K+ and the genetic manipulation of acetate kinase AckA and an RNA polymerase sigma factor SigE additively increased succinate and lactate production to 141.0 and 217.6 mg/L, which are 11 and 46 times, compared to the wild-type strain without K+, respectively. Intracellular levels of 2-oxoglutarate, succinate, fumarate, and malate increased by K+ under dark, anaerobic conditions. This study provides the evidence of the considerable effect of K+ on the biosynthesis of anionic metabolites in a unicellular cyanobacterium. PMID:27576448

  13. Continuous Drip Flow System to Develop Biofilm of E. faecalis under Anaerobic Conditions

    PubMed Central

    Gonzalez, Ana Maria; Corpus, Erika; Silva-Herzog, Daniel; Aragon-Piña, Antonio; Cohenca, Nestor

    2014-01-01

    Purpose. To evaluate a structurally mature E. faecalis biofilm developed under anaerobic/dynamic conditions in an in vitro system. Methods. An experimental device was developed using a continuous drip flow system designed to develop biofilm under anaerobic conditions. The inoculum was replaced every 24 hours with a fresh growth medium for up to 10 days to feed the system. Gram staining was done every 24 hours to control the microorganism purity. Biofilms developed under the system were evaluated under the scanning electron microscope (SEM). Results. SEM micrographs demonstrated mushroom-shaped structures, corresponding to a mature E. faecalis biofilm. In the mature biofilm bacterial cells are totally encased in a polymeric extracellular matrix. Conclusions. The proposed in vitro system model provides an additional useful tool to study the biofilm concept in endodontic microbiology, allowing for a better understanding of persistent root canal infections. PMID:25371913

  14. Anaerobic digestion in mesophilic and room temperature conditions: Digestion performance and soil-borne pathogen survival.

    PubMed

    Chen, Le; Jian, Shanshan; Bi, Jinhua; Li, Yunlong; Chang, Zhizhou; He, Jian; Ye, Xiaomei

    2016-05-01

    Tomato plant waste (TPW) was used as the feedstock of a batch anaerobic reactor to evaluate the effect of anaerobic digestion on Ralstonia solanacearum and Phytophthora capsici survival. Batch experiments were carried out for TS (total solid) concentrations of 2%, 4% and 6% respectively, at mesophilic (37±1°C) and room (20-25°C) temperatures. Results showed that higher digestion performance was achieved under mesophilic digestion temperature and lower TS concentration conditions. The biogas production ranged from 71 to 416L/kg VS (volatile solids). The inactivation of anaerobic digestion tended to increase as digestion performance improved. The maximum log copies reduction of R. solanacearum and P. capsici detected by quantitative PCR (polymerase chain reaction) were 3.80 and 4.08 respectively in reactors with 4% TS concentration at mesophilic temperatures. However, both in mesophilic and room temperature conditions, the lowest reduction of R. solanacearum was found in the reactors with 6% TS concentration, which possessed the highest VFA (volatile fatty acid) concentration. These findings indicated that simple accumulation of VFAs failed to restrain R. solanacearum effectively, although the VFAs were considered poisonous. P. capsici was nearly completely dead under all conditions. Based on the digestion performance and the pathogen survival rate, a model was established to evaluate the digestate biosafety.

  15. De novo assembly and comparative transcriptome analysis of Euglena gracilis in response to anaerobic conditions.

    PubMed

    Yoshida, Yuta; Tomiyama, Takuya; Maruta, Takanori; Tomita, Masaru; Ishikawa, Takahiro; Arakawa, Kazuharu

    2016-03-03

    The phytoflagellated protozoan, Euglena gracilis, has been proposed as an attractive feedstock for the accumulation of valuable compounds such as β-1,3-glucan, also known as paramylon, and wax esters. The production of wax esters proceeds under anaerobic conditions, designated as wax ester fermentation. In spite of the importance and usefulness of Euglena, the genome and transcriptome data are currently unavailable, though another research group has recently published E.gracilis transcriptome study during our submission. We herein performed an RNA-Seq analysis to provide a comprehensive sequence resource and some insights into the regulation of genes including wax ester metabolism by comparative transcriptome analysis of E.gracilis under aerobic and anaerobic conditions. The E.gracilis transcriptome analysis was performed using the Illumina platform and yielded 90.3 million reads after the filtering steps. A total of 49,826 components were assembled and identified as a reference sequence of E.gracilis, of which 26,479 sequences were considered to be potentially expressed (having FPKM value of greater than 1). Approximately half of all components were estimated to be regulated in a trans-splicing manner, with the addition of protruding spliced leader sequences. Nearly 40 % of 26,479 sequences were annotated by similarity to Swiss-Prot database using the BLASTX program. A total of 2080 transcripts were identified as differentially expressed genes (DEGs) in response to anaerobic treatment for 24 h. A comprehensive pathway enrichment analysis using the KEGG pathway revealed that the majority of DEGs were involved in photosynthesis, nucleotide metabolism, oxidative phosphorylation, fatty acid metabolism. We successfully identified a candidate gene set of paramylon and wax esters, including novel β-1,3-glucan and wax ester synthases. A comparative expression analysis of aerobic- and anaerobic-treated E.gracilis cells indicated that gene expression changes in these

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

    PubMed

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

    2015-05-15

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

  17. Influence of operational conditions on biofilm specific activity of an anaerobic fluidized bed reactor.

    PubMed

    García-Morales, J L; Romero, L I; Sales, D

    2003-01-01

    A key parameter in water and wastewater treatment technology is the biomass activity in terms of substrate removal ability. The effects of organic load rate and percentage of bed expansion on biofilm specific methanogenic activity were determined in an anaerobic fluidized bed reactor treating wine-distillery wastes in the thermophilic range (55 degrees C). The proposed activity tests are highly reproducible: an experiment with three identical tests has shown that the standard deviation with respect to the mean values is less than 3%. Specific tests are applied to measure the maximum methanogenic activities of the biomass carrier in lab-scale anaerobic biofilm reactors. These tests have been successfully applied for monitoring the support colonization process and the evolution of biofilm activity in reactors, anaerobic filter and fluidized bed, with different operating conditions. The results show a dependence between the percentage of bed expansion and the specific activity of methanogenic microbiote on biofilm. There is a relationship between the percentage of bed expansion, the sheer stress on the biofilm and the hydrodynamic conditions in the system. Initial biofilm detachment can be compensated with the increase of biomass and of its activity due to the reduction of the substrate diffusional limitations to the microorganism growth inside the support pores.

  18. A Hidden Transhydrogen Activity of a FMN-Bound Diaphorase under Anaerobic Conditions

    PubMed Central

    Collins, John; Zhang, Ting; Huston, Scott; Sun, Fangfang; Zhang, Y.-H. Percival; Fu, Jinglin

    2016-01-01

    Background Redox cofactors of NADH/NADPH participate in many cellular metabolic pathways for facilitating the electron transfer from one molecule to another in redox reactions. Transhydrogenase plays an important role in linking catabolism and anabolism, regulating the ratio of NADH/NADPH in cells. The cytoplasmic transhydrogenases could be useful to engineer synthetic biochemical pathways for the production of high-value chemicals and biofuels. Methodology/Principal Findings A transhydrogenase activity was discovered for a FMN-bound diaphorase (DI) from Geobacillus stearothermophilus under anaerobic conditions. The DI-catalyzed hydride exchange were monitored and characterized between a NAD(P)H and a thio-modified NAD+ analogue. This new function of DI was demonstrated to transfer a hydride from NADPH to NAD+ that was consumed by NAD-specific lactate dehydrogenase and malic dehydrogenase. Conclusions/Significance We discover a novel transhydrogenase activity of a FMN-DI by stabilizing the reduced state of FMNH2 under anaerobic conditions. FMN-DI was demonstrated to catalyze the hydride transfer between NADPH and NAD+. In the future, it may be possible to incorporate this FMN-DI into synthetic enzymatic pathways for balancing NADH generation and NADPH consumption for anaerobic production of biofuels and biochemicals. PMID:27145082

  19. Interrogation of Chesapeake Bay sediment microbial communities for intrinsic alkane-utilizing potential under anaerobic conditions.

    PubMed

    Johnson, Jamie M; Wawrik, Boris; Isom, Catherine; Boling, Wilford B; Callaghan, Amy V

    2015-02-01

    Based on the transient exposure of Chesapeake Bay sediments to hydrocarbons and the metabolic versatility of known anaerobic alkane-degrading microorganisms, it was hypothesized that distinct Bay sediment communities, governed by geochemical gradients, would have intrinsic alkane-utilizing potential under sulfate-reducing and/or methanogenic conditions. Sediment cores were collected along a transect of the Bay. Community DNA was interrogated via pyrosequencing of 16S rRNA genes, PCR of anaerobic hydrocarbon activation genes, and qPCR of 16S rRNA genes and genes involved in sulfate reduction/methanogenesis. Site sediments were used to establish microcosms amended with n-hexadecane under sulfate-reducing and methanogenic conditions. Sequencing of 16S rRNA genes indicated that sediments associated with hypoxic water columns contained significantly greater proportions of Bacteria and Archaea consistent with syntrophic degradation of organic matter and methanogenesis compared to less reduced sediments. Microbial taxa frequently associated with hydrocarbon-degrading communities were found throughout the Bay, and the genetic potential for hydrocarbon metabolism was demonstrated via the detection of benzyl-(bssA) and alkylsuccinate synthase (assA) genes. Although microcosm studies did not indicate sulfidogenic alkane degradation, the data suggested that methanogenic conversion of alkanes was occurring. These findings highlight the potential role that anaerobic microorganisms could play in the bioremediation of hydrocarbons in the Bay.

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

    PubMed

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

    2014-02-01

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

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

    PubMed

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

    2016-09-01

    Kinetics and thermodynamics of hydrolyzed polyacrylamide (HPAM) biodegradation in anaerobic and aerobic activated sludge biochemical treatment systems were explored to determine the maximum rate and feasibility of HPAM biodegradation. The optimal nutrient proportions for HPAM biodegradation were determined to be 0.08g·L(-1) C6H12O6, 1.00g·L(-1) NH4Cl, 0.36g·L(-1) NaH2PO4 and 3.00g·L(-1) K2HPO4 using response surface methodology (RSM). Based on the kinetics, the maximum HPAM biodegradation rates were 16.43385mg·L(-1)·d(-1) and 2.463mg·L(-1)·d(-1) in aerobic and anaerobic conditions, respectively. The activation energy (Ea) of the aerobic biodegradation was 48.9897kJ·mol(-1). Entropy changes (ΔS) of biochemical treatment system decreased from 216.21J·K(-1) to 2.39J·K(-1). Thermodynamic windows of opportunity for HPAM biodegradation were drawn. And it demonstrated HPAM was biodegraded into acetic acid and CO2 under laboratory conditions. Growth-process equations for functional bacteria anaerobically grown on polyacrylic acid were constructed and it confirmed electron equivalence between substrate and product. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Long-term geochemical evolution of acidic mine wastes under anaerobic conditions.

    PubMed

    Lu, Wenzhou; Lin, Chuxia; Ma, Yingqun

    2013-08-01

    A nearly 5-year anaerobic incubation experiment was conducted to observe the geochemical evolution of an acidic mine waste. Long-term storage of the mine waste under strict anaerobic conditions caused marked increase in aqueous sulfur, while aqueous iron showed no remarkable change. Co-existing oxidation and reduction of elemental sulfur appeared to play a central role in controlling the evolutionary trends of aqueous sulfur and iron. Addition of organic matter increased the aqueous Fe concentration, possibly due to enhanced iron mobilization by microbial iron reduction and increased iron solubility by forming organically complexed Fe species. Further addition of CaCO3 resulted in immobilization of aqueous iron and sulfur due to elevated pH and gypsum formation. The chemical behaviors of environmentally significant metals were markedly affected by the added organic matter; Al, Cr, Cu, Ni and Zn tended to be immobilized probably due to elevated pH and complexation with insoluble organic molecules, while As and Pb tended to be mobilized. Jarosite exhibited high stability after nearly 5 years of anaerobic incubation and even under circumneutral pH conditions. Long-term weathering of aluminosilicate through acid attack raised pH, while continuous reaction between the added CaCO3 and mine waste-borne stored acid decreased pH.

  3. Sulfate-reducing bacteria mediate thionation of diphenylarsinic acid under anaerobic conditions.

    PubMed

    Guan, Ling; Shiiya, Ayaka; Hisatomi, Shihoko; Fujii, Kunihiko; Nonaka, Masanori; Harada, Naoki

    2015-02-01

    Diphenylarsinic acid (DPAA) is often found as a toxic intermediate metabolite of diphenylchloroarsine or diphenylcyanoarsine that were produced as chemical warfare agents and were buried in soil after the World Wars. In our previous study Guan et al. (J Hazard Mater 241-242:355-362, 2012), after application of sulfate and carbon sources, anaerobic transformation of DPAA in soil was enhanced with the production of diphenylthioarsinic acid (DPTAA) as a main metabolite. This study aimed to isolate and characterize anaerobic soil microorganisms responsible for the metabolism of DPAA. First, we obtained four microbial consortia capable of transforming DPAA to DPTAA at a high transformation rate of more than 80% after 4 weeks of incubation. Sequencing for the bacterial 16S rRNA gene clone libraries constructed from the consortia revealed that all the positive consortia contained Desulfotomaculum acetoxidans species. In contrast, the absence of dissimilatory sulfite reductase gene (dsrAB) which is unique to sulfate-reducing bacteria was confirmed in the negative consortia showing no DPAA reduction. Finally, strain DEA14 showing transformation of DPAA to DPTAA was isolated from one of the positive consortia. The isolate was assigned to D. acetoxidans based on the partial 16S rDNA sequence analysis. Thionation of DPAA was also carried out in a pure culture of a known sulfate-reducing bacterial strain, Desulfovibrio aerotolerans JCM 12613(T). These facts indicate that sulfate-reducing bacteria are microorganisms responsible for the transformation of DPAA to DPTAA under anaerobic conditions.

  4. Enhanced anaerobic degradability of highly polluted pesticides-bearing wastewater under thermophilic conditions.

    PubMed

    García-Mancha, N; Monsalvo, V M; Puyol, D; Rodriguez, J J; Mohedano, A F

    2017-10-05

    This work presents a sustainable and cost-competitive solution for hardly biodegradable pesticides-bearing wastewater treatment in an anaerobic expanded granular sludge bed (EGSB) reactor at mesophilic (35°C) and thermophilic (55°C). The reactor was operated in continuous mode during 160days, achieving an average COD removal of 33 and 44% under mesophilic and thermophilic conditions, respectively. The increase of temperature improved the biomass activity and the production of methane by 35%. Around 96% of pesticides identified in raw wastewater were not detected in both mesophilic and thermophilic effluents. A dramatic selection of the microbial population in anaerobic granules was caused by the presence of pesticides, which also changed significantly when the temperature was increased. Pesticides caused a significant inhibition on methanogenesis, especially over acetoclastic methanogens. Aerobic biodegradability tests of the resulting anaerobic effluents revealed that aerobic post-treatment is also a feasible and effective option, yielding more than 60% COD reduction. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Dry co-digestion of sewage sludge and rice straw under mesophilic and thermophilic anaerobic conditions.

    PubMed

    Chu, Xiangqian; Wu, Guangxue; Wang, Jiaquan; Hu, Zhen-Hu

    2015-12-01

    Dry anaerobic digestion of sewage sludge can recover biogas as energy; however, its low C/N ratio limits it as a single substrate in the anaerobic digestion. Rice straw is an abundant agricultural residue in China, which is rich in carbon and can be used as carbon source. In the present study, the performance of dry co-digestion of sewage sludge and rice straw was investigated under mesophilic (35 °C) and thermophilic (55 °C) conditions. The operational factors impacting dry co-digestion of sewage sludge and rice straw such as C/N ratio, moisture content, and initial pH were explored under mesophilic conditions. The results show that low C/N ratios resulted in a higher biogas production rate, but a lower specific biogas yield; low moisture content of 65 % resulted in the instability of the digestion system and a low specific biogas yield. Initial pH ranging 7.0-9.0 did not affect the performance of the anaerobic digestion. The C/N ratio of 26-29:1, moisture content of 70-80 %, and pH 7.0-9.0 resulted in good performance in the dry mesophilic co-digestion of sewage sludge and rice straw. As compared with mesophilic digestion, thermophilic co-digestion of sewage sludge and rice straw significantly enhanced the degradation efficiency of the substrates and the specific biogas yield (p < 0.05) at the conditions of C/N ratio 26:1, moisture content 80 %, and natural initial pH. Although high concentrations of ammonia-nitrogen (NH4-N, 1500 mg/kg wet weight) were formed during thermophilic digestion, there was no obvious inhibition occurred. The results indicated that rice straw can be used as carbon source for the dry co-digestion of sewage sludge under mesophilic and thermophilic conditions.

  6. Anaerobic digestion of mixed microalgae cultivated in secondary effluent under mesophilic and thermophilic conditions.

    PubMed

    Cea-Barcia, Glenda; Moreno, Gloria; Buitrón, Germán

    2015-01-01

    The anaerobic digestion of mixed indigenous microalgae, grown in a secondary effluent, was evaluated in batch tests at mesophilic (35°C) and thermophilic (50°C) conditions. Under mesophilic conditions, specific methane production varied from 178 to 207 mL CH4/g volatile solids (VS) and the maximum production rate varied from 8.8 to 26.1 mL CH4/(gVS day), depending on the type of microalgae culture. Lower methane parameters were observed in those cultures where Scenedesmus represents more than 95% of the microalge. The culture with the lowest digestion performances under mesophilic conditions was studied under thermophilic conditions. The increase in the incubation temperature significantly increased the specific methane production (390 mL CH4/g VS) and rate (26.0 mL CH4/(gVS day)). However, under thermophilic conditions a lag period of 30 days was observed.

  7. Acyl homoserine lactone-based quorum sensing stimulates biofilm formation by Salmonella Enteritidis in anaerobic conditions.

    PubMed

    Almeida, Felipe Alves de; Pimentel-Filho, Natan de Jesus; Pinto, Uelinton Manoel; Mantovani, Hilário Cuquetto; Oliveira, Leandro Licursi de; Vanetti, Maria Cristina Dantas

    2017-04-01

    Quorum sensing regulates a variety of phenotypes in bacteria including the production of virulence factors. Salmonella spp. have quorum sensing systems mediated by three autoinducers (AI-1, AI-2, and AI-3). The AI-1-mediated system is incomplete in that the bacterium relies on the synthesis of signaling molecules by other microorganisms. This study aimed to evaluate the influence of the AI-1 N-dodecanoyl-DL-homoserine lactone (C12-HSL) on the growth, motility, adhesion, and biofilm formation of Salmonella enterica serovar Enteritidis PT4 578 on a polystyrene surface. Experiments were conducted at 37 °C in anaerobic tryptone soy broth supplemented with C12-HSL and/or a mixture of four synthetic furanones, at the concentration of 50 nM each. The planktonic growth, adhesion, swarming, and twitching motility were not altered in the presence of C12-HSL and/or furanones under anaerobic conditions. However, C12-HSL induced biofilm formation after 36 h of cultivation as determined by quantification of biofilm formation, by enumeration of adhered cells to polystyrene coupons, and finally by imaging the presence of multilayered cells on an epifluorescence microscope. When furanones were present in the medium, an antagonistic effect against C12-HSL on the biofilm development was observed. The results demonstrate an induction of biofilm formation in Salmonella Enteritidis by AI-1 under anaerobic conditions. Considering that Salmonella does not produce AI-1 but respond to it, C12-HSL synthesized by other bacterial species could trigger biofilm formation by this pathogen in conditions that are relevant for its pathogenesis.

  8. Antibiotic Susceptibilities of Pseudomonas aeruginosa Isolates Derived from Patients with Cystic Fibrosis under Aerobic, Anaerobic, and Biofilm Conditions

    PubMed Central

    Hill, Dominic; Rose, Barbara; Pajkos, Aniko; Robinson, Michael; Bye, Peter; Bell, Scott; Elkins, Mark; Thompson, Barbara; MacLeod, Colin; Aaron, Shawn D.; Harbour, Colin

    2005-01-01

    Recent studies have determined that Pseudomonas aeruginosa can live in a biofilm mode within hypoxic mucus in the airways of patients with cystic fibrosis (CF). P. aeruginosa grown under anaerobic and biofilm conditions may better approximate in vivo growth conditions in the CF airways, and combination antibiotic susceptibility testing of anaerobically and biofilm-grown isolates may be more relevant than traditional susceptibility testing under planktonic aerobic conditions. We tested 16 multidrug-resistant isolates of P. aeruginosa derived from CF patients using multiple combination bactericidal testing to compare the efficacies of double and triple antibiotic combinations against the isolates grown under traditional aerobic planktonic conditions, in planktonic anaerobic conditions, and in biofilm mode. Both anaerobically grown and biofilm-grown bacteria were significantly less susceptible (P < 0.01) to single and combination antibiotics than corresponding aerobic planktonically grown isolates. Furthermore, the antibiotic combinations that were bactericidal under anaerobic conditions were often different from those that were bactericidal against the same organisms grown as biofilms. The most effective combinations under all conditions were colistin (tested at concentrations suitable for nebulization) either alone or in combination with tobramycin (10 μg ml−1), followed by meropenem combined with tobramycin or ciprofloxacin. The findings of this study illustrate that antibiotic sensitivities are dependent on culture conditions and highlight the complexities of choosing appropriate combination therapy for multidrug-resistant P. aeruginosa in the CF lung. PMID:16207967

  9. Characterization of lighted upflow anaerobic sludge blanket (LUASB) method under sulfate-rich conditions.

    PubMed

    Sawayama, S; Tsukahara, K; Yagishita, T; Hanada, S

    2001-01-01

    Growth of phototrophic bacteria was induced from granules in a lighted upflow anaerobic sludge blanket (LUASB) reactor supplied with an organic-acid-based medium containing 141.7 mg S.l(-1) of SO4(2-) under light conditions (100 microE.m(-2).s(-1)). We investigated the population dynamics of phototrophic bacteria in the LUASB reactor and the performance of the LUASB reactor for wastewater treatment and poly-beta-hydroxybutyrate (PHB) production under anaerobic light and sulfate-rich conditions. In vivo absorption spectra and a colony count suggested that populations of Rhodopseudomonas palustris and Blastochloris sulfoviridis in the LUASB reactor supplied with a medium containing 574.4 mg S.l(-1) of SO4(2-) under light conditions were lower than those supplied with a medium containing 1.0 or 141.7 mg S.l(-1) of SO4(2-) under parallel conditions. Removal efficiencies of ammonium and phosphate in the LUASB reactor supplied with the medium containing 141.7 mg S.l(-1) of SO4(2-) under light conditions were higher than those under parallel conditions but without illumination. The difference in the results of runs under light or dark conditions suggested that the ammonium and phosphate ion removal efficiencies were improved by increasing the amount of phototrophic bacterial biomass in the LUASB reactor under sulfate-rich conditions. The average PHB production rates of the bacterial cells recovered from the effluent of the LUASB reactor supplied with a medium containing 141.7, 283.5 or 574.4 mg S.l(-1) of SO4(2-) were 1.0-2.9 mg.l(-1)-reactor.d(-1) and the average PHB content based on the dry bacterial biomass was 1.4-3.6%.

  10. A Portable Anaerobic Microbioreactor Reveals Optimum Growth Conditions for the Methanogen Methanosaeta concilii▿

    PubMed Central

    Steinhaus, Benjamin; Garcia, Marcelo L.; Shen, Amy Q.; Angenent, Largus T.

    2007-01-01

    Conventional studies of the optimum growth conditions for methanogens (methane-producing, obligate anaerobic archaea) are typically conducted with serum bottles or bioreactors. The use of microfluidics to culture methanogens allows direct microscopic observations of the time-integrated response of growth. Here, we developed a microbioreactor (μBR) with ∼1-μl microchannels to study some optimum growth conditions for the methanogen Methanosaeta concilii. The μBR is contained in an anaerobic chamber specifically designed to place it directly onto an inverted light microscope stage while maintaining a N2-CO2 environment. The methanogen was cultured for months inside microchannels of different widths. Channel width was manipulated to create various fluid velocities, allowing the direct study of the behavior and responses of M. concilii to various shear stresses and revealing an optimum shear level of ∼20 to 35 μPa. Gradients in a single microchannel were then used to find an optimum pH level of 7.6 and an optimum total NH4-N concentration of less than 1,100 mg/liter (<47 mg/liter as free NH3-N) for M. concilii under conditions of the previously determined ideal shear stress and pH and at a temperature of 35°C. PMID:17220251

  11. Investigating the nitrification and denitrification kinetics under aerobic and anaerobic conditions by Paracoccus denitrificans ISTOD1.

    PubMed

    Medhi, Kristina; Singhal, Anjali; Chauhan, D K; Thakur, Indu Shekhar

    2017-03-16

    Municipal wastewater contains multiple nitrogen contaminants such as ammonia, nitrate and nitrite. Two heterotrophic nitrifier and aerobic denitrifiers, bacterial isolates ISTOD1 and ISTVD1 were isolated from domestic wastewater. On the basis of removal efficiency of ammonia, nitrate and nitrite under both aerobic and anaerobic conditions, ISTOD1 was selected and identified as Paracoccus denitrificans. Aerobically, NH4(+)-N had maximum specific nitrogen removal rate (Rxi) of 7.6g/gDCW/h and anaerobically, NO3(-)N showed Rxi of 2.5*10(-1)g/g DCW/h. Monod equation described the bioprocess kinetic coefficients, µmax and Ks, obtained by regression. Error functions were calculated to validate the Monod equation experimental data. Aerobic NO3(-)N showed the highest YW of 0.372mg DCW/mg NO3(-)N among the five conditions. ISTOD1 serves as a potential candidate for treating nitrogen rich wastewater using simultaneous nitrification and aerobic denitrification. It can be used in bioaugmentation studies under varied condition.

  12. Anaerobic digestion of raw and thermally hydrolyzed wastewater solids under various operational conditions.

    PubMed

    Wilson, Christopher A; Tanneru, Charan T; Banjade, Sarita; Murthy, Sudhir N; Novak, John T

    2011-09-01

    In this study, high-solids anaerobic digestion of thermally pretreated wastewater solids (THD) was compared with conventional mesophilic anaerobic digestion (MAD). Operational conditions, such as pretreatment temperature (150 to 170 degrees C), solids retention time (15 to 20 days), and digestion temperature (37 to 42 degrees C), were varied for the seven THD systems operated. Volatile solids reduction (VSR) by THD ranged from 56 to 62%, compared with approximately 50% for MAD. Higher VSR contributed to 24 to 59% increased biogas production (m3/kg VSR-d) from THD relative to MAD. The high-solids conditions of the THD feed resulted in high total ammonia-nitrogen (proportional to solids loading) and total alkalinity concentrations in excess of 14 g/L as calcium carbonate (CaCO3). Increased pH in THD reactors caused 5 to 8 times more un-ionized ammonia to be present than in MAD, and this likely led to inhibition of aceticlastic methanogens, resulting in accumulation of residual volatile fatty acids between 2 and 6 g/L as acetic acid. The THD produced biosolids cake that possessed low organic sulfur-based biosolids odor and dewatered to between 33 and 39% total solids. Dual conditioning with cationic polymer and ferric chloride was shown to be an effective strategy for mitigating dissolved organic nitrogen and UV-quenching compounds in the return stream following centrifugal dewatering of THD biosolids.

  13. Microbial metabolism of pyridine, quinoline, acridine, and their derivatives under aerobic and anaerobic conditions.

    PubMed Central

    Kaiser, J P; Feng, Y; Bollag, J M

    1996-01-01

    Our review of the metabolic pathways of pyridines and aza-arenes showed that biodegradation of heterocyclic aromatic compounds occurs under both aerobic and anaerobic conditions. Depending upon the environmental conditions, different types of bacteria, fungi, and enzymes are involved in the degradation process of these compounds. Our review indicated that different organisms are using different pathways to biotransform a substrate. Our review also showed that the transformation rate of the pyridine derivatives is dependent on the substituents. For example, pyridine carboxylic acids have the highest transformation rate followed by mono-hydroxypyridines, methylpyridines, aminopyridines, and halogenated pyridines. Through the isolation of metabolites, it was possible to demonstrate the mineralization pathway of various heterocyclic aromatic compounds. By using 14C-labeled substrates, it was possible to show that ring fission of a specific heterocyclic compound occurs at a specific position of the ring. Furthermore, many researchers have been able to isolate and characterize the microorganisms or even the enzymes involved in the transformation of these compounds or their derivatives. In studies involving 18O labeling as well as the use of cofactors and coenzymes, it was possible to prove that specific enzymes (e.g., mono- or dioxygenases) are involved in a particular degradation step. By using H2 18O, it could be shown that in certain transformation reactions, the oxygen was derived from water and that therefore these reactions might also occur under anaerobic conditions. PMID:8840783

  14. Uranium Biominerals Precipitated by an Environmental Isolate of Serratia under Anaerobic Conditions

    PubMed Central

    Newsome, Laura; Morris, Katherine; Lloyd, Jonathan. R.

    2015-01-01

    Stimulating the microbially-mediated precipitation of uranium biominerals may be used to treat groundwater contamination at nuclear sites. The majority of studies to date have focussed on the reductive precipitation of uranium as U(IV) by U(VI)- and Fe(III)-reducing bacteria such as Geobacter and Shewanella species, although other mechanisms of uranium removal from solution can occur, including the precipitation of uranyl phosphates via bacterial phosphatase activity. Here we present the results of uranium biomineralisation experiments using an isolate of Serratia obtained from a sediment sample representative of the Sellafield nuclear site, UK. When supplied with glycerol phosphate, this Serratia strain was able to precipitate 1 mM of soluble U(VI) as uranyl phosphate minerals from the autunite group, under anaerobic and fermentative conditions. Under phosphate-limited anaerobic conditions and with glycerol as the electron donor, non-growing Serratia cells could precipitate 0.5 mM of uranium supplied as soluble U(VI), via reduction to nano-crystalline U(IV) uraninite. Some evidence for the reduction of solid phase uranyl(VI) phosphate was also observed. This study highlights the potential for Serratia and related species to play a role in the bioremediation of uranium contamination, via a range of different metabolic pathways, dependent on culturing or in situ conditions. PMID:26132209

  15. Isolation and characterization of a sulfur-oxidizing chemolithotroph growing on crude oil under anaerobic conditions.

    PubMed

    Kodama, Yumiko; Watanabe, Kazuya

    2003-01-01

    Molecular approaches have shown that a group of bacteria (called cluster 1 bacteria) affiliated with the epsilon subclass of the class Proteobacteria constituted major populations in underground crude-oil storage cavities. In order to unveil their physiology and ecological niche, this study isolated bacterial strains (exemplified by strain YK-1) affiliated with the cluster 1 bacteria from an oil storage cavity at Kuji in Iwate, Japan. 16S rRNA gene sequence analysis indicated that its closest relative was Thiomicrospira denitrificans (90% identity). Growth experiments under anaerobic conditions showed that strain YK-1 was a sulfur-oxidizing obligate chemolithotroph utilizing sulfide, elemental sulfur, thiosulfate, and hydrogen as electron donors and nitrate as an electron acceptor. Oxygen also supported its growth only under microaerobic conditions. Strain YK-1 could not grow on nitrite, and nitrite was the final product of nitrate reduction. Neither sugars, organic acids (including acetate), nor hydrocarbons could serve as carbon and energy sources. A typical stoichiometry of its energy metabolism followed an equation: S(2-) + 4NO(3)(-) --> SO(4)(2-) + 4NO(2)(-) (Delta G(0) = -534 kJ mol(-1)). In a difference from other anaerobic sulfur-oxidizing bacteria, this bacterium was sensitive to NaCl; growth in medium containing more than 1% NaCl was negligible. When YK-1 was grown anaerobically in a sulfur-depleted inorganic medium overlaid with crude oil, sulfate was produced, corresponding to its growth. On the contrary, YK-1 could not utilize crude oil as a carbon source. These results suggest that the cluster 1 bacteria yielded energy for growth in oil storage cavities by oxidizing petroleum sulfur compounds. Based on its physiology, ecological interactions with other members of the groundwater community are discussed.

  16. Suppression of Eis and expression of Wag31 and GroES in Mycobacterium tuberculosis cytosol under anaerobic culture conditions.

    PubMed

    Maurya, Vineet K; Singh, Kavita; Sinha, Sudhir

    2014-08-01

    A major impediment in chemotherapy of Tuberculosis (TB) is the persistence of M. tuberculosis in a latent or dormant state, possibly perpetuated by paucity of oxygen within the lung granuloma. Proteome analysis of the anaerobically persisting microbe could therefore provide novel targets for drugs against latent TB infection (LTBI). An Indian clinical isolate of M. tuberculosis was cultured under aerobic and anaerobic conditions following Wayne's hypoxia model and its cytosolic proteins were resolved by two-dimensional gel electrophoresis (2DE). Peptide mass fingerprinting of 32 differentially expressed spots using MALDI TOF-TOF MS-MS resulted in identification of 23 proteins. Under the anaerobic culture conditions, expression of 12 of these proteins was highly suppressed (>2 fold reduction in spot volumes), with 4 of them (GrpE, CanB, MoxR1 and Eis) appearing as completely suppressed since corresponding spots were not detectable in the anaerobic sample. On the other hand, 4 proteins were highly expressed, with two of them (Wag31 and GroES) being uniquely expressed under anaerobic conditions. Suppression of Eis could make the anaerobically persisting bacilli susceptible to the aminoglycoside antibiotics which are known to be acetylated and inactivated by Eis. Although all 4 overexpressed proteins can be considered as putative drug targets for LTBI, Wag31 appears particularly interesting in view of its role in the cell wall biogenesis.

  17. Influence of extreme ambient temperatures and anaerobic conditions on Peltigera aphthosa (L.) Willd. viability

    NASA Astrophysics Data System (ADS)

    Dyakov, M. Yu.; Insarova, I. D.; Kharabadze, D. E.; Ptushenko, V. V.; Shtaer, O. V.

    2015-11-01

    Lichen are symbiotic systems constituted by heterotrophic fungi (mycobionts) and photosynthetic microorganism (photobionts). These organisms can survive under extreme stress conditions. The aim of this work was to study the influence of low (- 70 °C) or high (+ 70 °C) temperatures, temperature fluctuations from + 70 °C to - 70 °C, and anaerobic conditions on P. aphthosa (L.) Willd. viability. None of the studied stress factors affected significantly photosynthetic and respiratory activity of the thalli. No changes in morphology or ultrastructure of the cells were revealed for both photobiont and mycobiont components after extreme temperature treatment of P. aphthosa thalli. The data show the extreme tolerance of P. aphthosa to some stress factors inherent to the space flight conditions.

  18. Quantitative proteome and transcriptome analysis of the archaeon Thermoplasma acidophilum cultured under aerobic and anaerobic conditions.

    PubMed

    Sun, Na; Pan, Cuiping; Nickell, Stephan; Mann, Matthias; Baumeister, Wolfgang; Nagy, István

    2010-09-03

    A comparative proteome and transcriptome analysis of Thermoplasma acidophilum cultured under aerobic and anaerobic conditions has been performed. One-thousand twenty-five proteins were identified covering 88% of the cytosolic proteome. Using a label-free quantitation method, we found that approximately one-quarter of the identified proteome (263 proteins) were significantly induced (>2 fold) under anaerobic conditions. Thirty-nine macromolecular complexes were identified, of which 28 were quantified and 15 were regulated under anaerobiosis. In parallel, a whole genome cDNA microarray analysis was performed showing that the expression levels of 445 genes were influenced by the absence of oxygen. Interestingly, more than 40% of the membrane protein-encoding genes (145 out of 335 ORFs) were up- or down-regulated at the mRNA level. Many of these proteins are functionally associated with extracellular protein or peptide degradation or ion and amino acid transport. Comparison of the transcriptome and proteome showed only a weak positive correlation between mRNA and protein expression changes, which is indicative of extensive post-transcriptional regulatory mechanisms in T. acidophilum. Integration of transcriptomics and proteomics data generated hypotheses for physiological adaptations of the cells to anaerobiosis, and the quantitative proteomics data together with quantitative analysis of protein complexes provide a platform for correlation of MS-based proteomics studies with cryo-electron tomography-based visual proteomics approaches.

  19. Formation of diphenylthioarsinic acid from diphenylarsinic acid under anaerobic sulfate-reducing soil conditions.

    PubMed

    Hisatomi, Shihoko; Guan, Ling; Nakajima, Mami; Fujii, Kunihiko; Nonaka, Masanori; Harada, Naoki

    2013-11-15

    Diphenylarsinic acid (DPAA) is a toxic phenylarsenical compound often found around sites contaminated with phenylarsenic chemical warfare agents, diphenylcyanoarsine or diphenylchloroarsine, which were buried in soil after the World Wars. This research concerns the elucidation of the chemical structure of an arsenic metabolite transformed from DPAA under anaerobic sulfate-reducing soil conditions. In LC/ICP-MS analysis, the retention time of the metabolite was identical to that of a major phenylarsenical compound synthesized by chemical reaction of DPAA and hydrogen sulfide. Moreover the mass spectra for the two compounds measured using LC/TOF-MS were similar. Subsequent high resolution mass spectral analysis indicated that two major ions at m/z 261 and 279, observed on both mass spectra, were attributable to C12H10AsS and C12H12AsSO, respectively. These findings strongly suggest that the latter ion is the molecular-related ion ([M+H](+)) of diphenylthioarsinic acid (DPTA; (C6H5)2AsS(OH)) and the former ion is its dehydrated fragment. Thus, our results reveal that DPAA can be transformed to DPTA, as a major metabolite, under sulfate-reducing soil conditions. Moreover, formation of diphenyldithioarsinic acid and subsequent dimerization were predicted by the chemical reaction analysis of DPAA with hydrogen sulfide. This is the first report to elucidate the occurrence of DPAA-thionation in an anaerobic soil.

  20. Mechanism of xanthine oxidase catalyzed biotransformation of HMX under anaerobic conditions.

    PubMed

    Bhushan, Bharat; Paquet, Louise; Halasz, Annamaria; Spain, Jim C; Hawari, Jalal

    2003-06-27

    Enzyme catalyzed biotransformation of the energetic chemical octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) is not known. The present study describes a xanthine oxidase (XO) catalyzed biotransformation of HMX to provide insight into the biodegradation pathway of this energetic chemical. The rates of biotransformation under aerobic and anaerobic conditions were 1.6+/-0.2 and 10.5+/-0.9 nmolh(-1)mgprotein(-1), respectively, indicating that anaerobic conditions favored the reaction. The biotransformation rate was about 6-fold higher using NADH as an electron-donor compared to xanthine. During the course of reaction, the products obtained were nitrite (NO(2)(-)), methylenedinitramine (MDNA), 4-nitro-2,4-diazabutanal (NDAB), formaldehyde (HCHO), nitrous oxide (N(2)O), formic acid (HCOOH), and ammonium (NH(4)(+)). The product distribution gave carbon and nitrogen mass-balances of 91% and 88%, respectively. A comparative study with native-, deflavo-, and desulfo-XO and the site-specific inhibition studies showed that HMX biotransformation occurred at the FAD-site of XO. Nitrite stoichiometry revealed that an initial single N-denitration step was sufficient for the spontaneous decomposition of HMX.

  1. Determination of operating conditions in an anaerobic acid-phase reactor treating dairy wastewater

    SciTech Connect

    Kasapgil, B.; Ince, O.; Anderson, G.K.

    1996-11-01

    Anaerobic digestion of organic material is a multistep process. Two groups of bacteria, namely acidogenic and methanogenic bacteria, are responsible for the acidification and for the methane formation, respectively. The growth requirements of the two groups of bacteria are rather different. In order to create optimum conditions for the process, it was first proposed to separate the process into two phases. Operating variables applicable for the selection and enrichment of microbial populations in phased digesters include digester loading, hydraulic retention time (HRT), pH, temperature, reactor design, and operating mode. By proper manipulation of these operating parameters it is possible to prevent any significant growth of methane bacteria and at the same time achieve the required level of acidification in the first reactor. Further enrichment of two cultures is possible by biomass recycle around each phase. Since the 1970s, phase separation has been introduced into anaerobic digestion technology. However, data concerning the optimization of operating conditions in both acidogenic and methanogenic phase reactors are scarce. This study was therefore carried out for the purposes given below. These were: (1) to determine the best combination of pH and temperature within the ranges studied for the pre-acidification of dairy wastewater; (2) to determine the maximum acidogenic conversion from COD to VFAs, and (3) to determine the changes in the distribution of major VFAs being produced during the pre-acidification of dairy wastewater.

  2. Breaking The Enzymatic Latch: Do Anaerobic Conditions Constrain Decomposition In Humid Tropical Forest Soil?

    NASA Astrophysics Data System (ADS)

    Hall, S. J.; Silver, W. L.

    2011-12-01

    Anaerobic conditions have been proposed to impose a "latch" on soil organic matter decomposition by inhibiting the activity of extracellular enzymes that catalyze the transformation of organic polymers into monomers for microbial assimilation. Here, we tested the hypothesis that anaerobiosis inhibits soil hydrolytic enzyme activity in a humid tropical forest ecosystem in Puerto Rico. We sampled surface and sub-surface soil from each of 59 plots (n = 118) stratified across distinct topographical zones (ridges, slopes, and valleys) known to vary in soil oxygen (O2) concentrations, and measured the potential activity of five hydrolytic enzymes that decompose carbon (C), nitrogen (N), and phosphorus (P) substrates. We measured reduced iron (Fe (II)) concentrations in soil extractions to provide a spatially and temporally integrated index of anaerobic microbial activity, since iron oxides constitute the dominant anaerobic terminal electron acceptor in this ecosystem. Surprisingly, we observed positive relationships between Fe (II) concentrations and the activity of all enzymes that we assayed. Linear mixed effects models that included Fe (II) concentration, topographic position, and their interaction explained between 30 to 70 % of the variance of enzyme activity of β-1,4-glucosidase, β-cellobiohydrolase, β-xylosidase, N-acetylglucosaminidase, and acid phosphatase. Soils from ridges and slopes contained between 10 and 800 μg Fe (II) g-1 soil, and exhibited consistently positive relationships (p < 0.0001) between Fe (II) and enzyme activity. Valley soils did not display significant relationships between enzyme activity and Fe (II), although they displayed variation in soil Fe (II) concentrations similar to ridges and slopes. Overall, valleys exhibited lower enzyme activity and lower Fe (II) concentrations than ridges or slopes, possibly related to decreased root biomass and soil C. Our data provide no indication that anaerobiosis suppresses soil enzyme activity, but

  3. High-solids anaerobic mono-digestion of riverbank grass under thermophilic conditions.

    PubMed

    Andriamanohiarisoamanana, Fetra J; Matsunami, Nobuyuki; Yamashiro, Takaki; Iwasaki, Masahiro; Ihara, Ikko; Umetsu, Kazutaka

    2017-02-01

    The purpose of this study was to investigate the potential of high-solids anaerobic mono-digestion of riverbank grass under thermophilic conditions, focusing on the effects of the strength and the amount of inoculum. Ensiled grass was inoculated with three different inocula; inoculum from liquid anaerobic digester (LI), inoculum from dry anaerobic digester (DI), and mixture of LI and DI (MI), at feedstock-to-inoculum ratio (FIR) of 1, 2 and 4. The ensiling process of riverbank grass reduced moisture content (p>0.05), while the hemicellulose content was significantly increased from 30.88% to 35.15% (p<0.05), on dry matter basis. The highest methane production was at an FIR of 2 with MI (167L/kg VSadded), which was significantly higher (p<0.05) than with DI, but not significant compared to LI (p>0.05). At an FIR of 4, digesters inoculated with LI and DI failed to produce methane, whereas 135LCH4/kg VSadded was obtained with MI. The kinetic studies showed that at an FIR of 1 with LI and MI, the inoculum had less of effects on the hydrolysis rate constant (0.269day(-1) and 0.245day(-1)) and methane production (135 versus 149L/kg VSadded); rather, it affected the lag phase. In a thermophilic HS-AD of riverbank grass, the mixture of inoculum with low and high total solids content (TS) helps increase the TS of inoculum and digestion process. An FIR of 2 was deducted to be the limit for a better startup time and higher volumetric productivity of methane. Copyright © 2016. Published by Elsevier B.V.

  4. Oxygen Consumption by Anaerobic Saccharomyces cerevisiae under Enological Conditions: Effect on Fermentation Kinetics

    PubMed Central

    Rosenfeld, Eric; Beauvoit, Bertrand; Blondin, Bruno; Salmon, Jean-Michel

    2003-01-01

    The anaerobic growth of the yeast Saccharomyces cerevisiae normally requires the addition of molecular oxygen, which is used to synthesize sterols and unsaturated fatty acids (UFAs). A single oxygen pulse can stimulate enological fermentation, but the biochemical pathways involved in this phenomenon remain to be elucidated. We showed that the addition of oxygen (0.3 to 1.5 mg/g [dry mass] of yeast) to a lipid-depleted medium mainly resulted in the synthesis of the sterols and UFAs required for cell growth. However, the addition of oxygen during the stationary phase in a medium containing excess ergosterol and oleic acid increased the specific fermentation rate, increased cell viability, and shortened the fermentation period. Neither the respiratory chain nor de novo protein synthesis was required for these medium- and long-term effects. As de novo lipid synthesis may be involved in ethanol tolerance, we studied the effect of oxygen addition on sterol and UFA auxotrophs (erg1 and ole1 mutants, respectively). Both mutants exhibited normal anaerobic fermentation kinetics. However, only the ole1 mutant strain responded to the oxygen pulse during the stationary phase, suggesting that de novo sterol synthesis is required for the oxygen-induced increase of the specific fermentation rate. In conclusion, the sterol pathway appears to contribute significantly to the oxygen consumption capacities of cells under anaerobic conditions. Nevertheless, we demonstrated the existence of alternative oxygen consumption pathways that are neither linked to the respiratory chain nor linked to heme, sterol, or UFA synthesis. These pathways dissipate the oxygen added during the stationary phase, without affecting the fermentation kinetics. PMID:12513985

  5. Anaerobic Naphthalene Degradation by Microbial Pure Cultures under Nitrate-Reducing Conditions

    PubMed Central

    Rockne, Karl J.; Chee-Sanford, Joanne C.; Sanford, Robert A.; Hedlund, Brian P.; Staley, James T.; Strand, Stuart E.

    2000-01-01

    Pure bacterial cultures were isolated from a highly enriched denitrifying consortium previously shown to anaerobically biodegrade naphthalene. The isolates were screened for the ability to grow anaerobically in liquid culture with naphthalene as the sole source of carbon and energy in the presence of nitrate. Three naphthalene-degrading pure cultures were obtained, designated NAP-3-1, NAP-3-2, and NAP-4. Isolate NAP-3-1 tested positive for denitrification using a standard denitrification assay. Neither isolate NAP-3-2 nor isolate NAP-4 produced gas in the assay, but both consumed nitrate and NAP-4 produced significant amounts of nitrite. Isolates NAP-4 and NAP-3-1 transformed 70 to 90% of added naphthalene, and the transformation was nitrate dependent. No significant removal of naphthalene occurred under nitrate-limited conditions or in cell-free controls. Both cultures exhibited partial mineralization of naphthalene, representing 7 to 20% of the initial added 14C-labeled naphthalene. After 57 days of incubation, the largest fraction of the radiolabel in both cultures was recovered in the cell mass (30 to 50%), with minor amounts recovered as unknown soluble metabolites. Nitrate consumption, along with the results from the 14C radiolabel study, are consistent with the oxidation of naphthalene coupled to denitrification for NAP-3-1 and nitrate reduction to nitrite for NAP-4. Phylogenetic analyses based on 16S ribosomal DNA sequences of NAP-3-1 showed that it was closely related to Pseudomonas stutzeri and that NAP-4 was closely related to Vibrio pelagius. This is the first report we know of that demonstrates nitrate-dependent anaerobic degradation and mineralization of naphthalene by pure cultures. PMID:10742247

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

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

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

  7. Transposon mutagenesis identified chromosomal and plasmid genes essential for adaptation of the marine bacterium Dinoroseobacter shibae to anaerobic conditions.

    PubMed

    Ebert, Matthias; Laaß, Sebastian; Burghartz, Melanie; Petersen, Jörn; Koßmehl, Sebastian; Wöhlbrand, Lars; Rabus, Ralf; Wittmann, Christoph; Tielen, Petra; Jahn, Dieter

    2013-10-01

    Anaerobic growth and survival are integral parts of the life cycle of many marine bacteria. To identify genes essential for the anoxic life of Dinoroseobacter shibae, a transposon library was screened for strains impaired in anaerobic denitrifying growth. Transposon insertions in 35 chromosomal and 18 plasmid genes were detected. The essential contribution of plasmid genes to anaerobic growth was confirmed with plasmid-cured D. shibae strains. A combined transcriptome and proteome approach identified oxygen tension-regulated genes. Transposon insertion sites of a total of 1,527 mutants without an anaerobic growth phenotype were determined to identify anaerobically induced but not essential genes. A surprisingly small overlap of only three genes (napA, phaA, and the Na(+)/Pi antiporter gene Dshi_0543) between anaerobically essential and induced genes was found. Interestingly, transposon mutations in genes involved in dissimilatory and assimilatory nitrate reduction (napA, nasA) and corresponding cofactor biosynthesis (genomic moaB, moeB, and dsbC and plasmid-carried dsbD and ccmH) were found to cause anaerobic growth defects. In contrast, mutation of anaerobically induced genes encoding proteins required for the later denitrification steps (nirS, nirJ, nosD), dimethyl sulfoxide reduction (dmsA1), and fermentation (pdhB1, arcA, aceE, pta, acs) did not result in decreased anaerobic growth under the conditions tested. Additional essential components (ferredoxin, cccA) of the anaerobic electron transfer chain and central metabolism (pdhB) were identified. Another surprise was the importance of sodium gradient-dependent membrane processes and genomic rearrangements via viruses, transposons, and insertion sequence elements for anaerobic growth. These processes and the observed contributions of cell envelope restructuring (lysM, mipA, fadK), C4-dicarboxylate transport (dctM1, dctM3), and protease functions to anaerobic growth require further investigation to unravel the

  8. Microbial Ecology in Anaerobic Digestion at Agitated and Non-Agitated Conditions

    PubMed Central

    Tian, Zhuoli; Cabrol, Léa; Ruiz-Filippi, Gonzalo; Pullammanappallil, Pratap

    2014-01-01

    To investigate the distribution and dynamics of microbial community in anaerobic digestion at agitated and non-agitated condition, 454 pyrosequencing of 16s rRNA was conducted. It revealed the distinct community compositions between the two digesters and their progressive shifting over time. Methanogens and syntrophic bacteria were found much less abundant in the agitated digester, which was mainly attributed to the presence of bacterial genera Acetanaerobacterium and Ruminococcus with relatively high abundance. The characterization of the microbial community corroborated the digestion performance affected at the agitated condition, where lower methane yield and delayed methane production rate were observed. This was further verified by the accumulation of propionic acid in the agitated digester. PMID:25313520

  9. Detailed observation and measurement of sewer sediment erosion under aerobic and anaerobic conditions.

    PubMed

    Schellart, A; Veldkamp, R; Klootwijk, M; Clemens, F; Tait, S; Ashley, R; Howes, C

    2005-01-01

    A greater understanding of the erosion behaviour of sewer sediments is necessary in order to reliably estimate the amount and nature of the sewer sediments released from deposits in sewers and transported either to waste water treatment plants or discharged into the environment. Research has indicated that microbial activity in sediment can influence the physical release of sediment from in-pipe deposits. This paper reports on a series of erosion tests in which sewer sediments from different sewer networks are kept under different environmental conditions and their resistance to erosion is examined. The erosion tests are carried out under aerobic and anaerobic conditions and two temperatures, one representing ambient sewer temperatures and a lower temperature that significantly suppresses bacterial activity.

  10. Anaerobic digestion of the microalga Spirulina at extreme alkaline conditions: biogas production, metagenome, and metatranscriptome

    PubMed Central

    Nolla-Ardèvol, Vímac; Strous, Marc; Tegetmeyer, Halina E.

    2015-01-01

    A haloalkaline anaerobic microbial community obtained from soda lake sediments was used to inoculate anaerobic reactors for the production of methane rich biogas. The microalga Spirulina was successfully digested by the haloalkaline microbial consortium at alkaline conditions (pH 10, 2.0 M Na+). Continuous biogas production was observed and the obtained biogas was rich in methane, up to 96%. Alkaline medium acted as a CO2 scrubber which resulted in low amounts of CO2 and no traces of H2S in the produced biogas. A hydraulic retention time (HRT) of 15 days and 0.25 g Spirulina L−1 day−1 organic loading rate (OLR) were identified as the optimal operational parameters. Metagenomic and metatranscriptomic analysis showed that the hydrolysis of the supplied substrate was mainly carried out by Bacteroidetes of the “ML635J-40 aquatic group” while the hydrogenotrophic pathway was the main producer of methane in a methanogenic community dominated by Methanocalculus. PMID:26157422

  11. Reductive dechlorination of methoxychlor and DDT by human intestinal bacterium Eubacterium limosum under anaerobic conditions.

    PubMed

    Yim, You-Jin; Seo, Jiyoung; Kang, Su-Il; Ahn, Joong-Hoon; Hur, Hor-Gil

    2008-04-01

    Methoxychlor [1,1,1-trichloro-2,2-bis(p-methoxyphenyl)ethane], a substitute for 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT), is a compound of environmental concern because of potential long-term health risks related to its endocrine-disrupting and carcinogenic potency. In order to determine the metabolic fate of methoxychlor and DDT in the human intestinal gut, Eubacterium limosum (ATCC 8486), a strict anaerobe isolated from the human intestine that is capable of O-demethylation toward O-methylated isoflavones, was used as a model intestinal microbial organism. Under anaerobic incubation conditions, E. limosum completely transformed methoxychlor and DDT in 16 days. Based on gas chromatography-mass chromatography analyses, the metabolites produced from methoxychlor and DDT by E. limosum were confirmed to be 1,1-dichloro-2,2-bis(p-methoxyphenyl)ethane (methoxydichlor) and 1,1-dichloro-2,2-bis(p-chlorophenyl)ethane (DDD), respectively. This study suggests that E. limosum in the human intestinal gut might be a participant in the reductive dechlorination of methoxychlor to the more antiandrogenic active methoxydichlor.

  12. Study of the operational conditions for anaerobic digestion of urban solid wastes

    SciTech Connect

    Castillo M, Edgar Fernando . E-mail: efcastil@uis.edu.co; Cristancho, Diego Edison; Victor Arellano, A.

    2006-07-01

    This paper describes an experimental evaluation of anaerobic digestion technology as an option for the management of organic solid waste in developing countries. As raw material, a real and heterogeneous organic waste from urban solid wastes was used. In the first experimental phase, seed selection was achieved through an evaluation of three different anaerobic sludges coming from wastewater treatment plants. The methanization potential of these sludges was assessed in three different batch digesters of 500 mL, at two temperature levels. The results showed that by increasing the temperature to 15 deg. C above room temperature, the methane production increases to three times. So, the best results were obtained in the digester fed with a mixed sludge, working at mesophilic conditions (38-40 deg. C). Then, this selected seed was used at the next experimental phase, testing at different digestion times (DT) of 25, 20 and 18 days in a bigger batch digester of 20 L with a reaction volume of 13 L. The conversion rates were registered at the lowest DT (18 days), reaching 44.9 L/kg{sup -1} of wet waste day{sup -1}. Moreover, DT also has a strong influence over COD removal, because there is a direct relationship between solids removal inside the reactor and DT.

  13. Study of the operational conditions for anaerobic digestion of urban solid wastes.

    PubMed

    M, Edgar Fernando Castillo; Cristancho, Diego Edison; Arellano, A Victor

    2006-01-01

    This paper describes an experimental evaluation of anaerobic digestion technology as an option for the management of organic solid waste in developing countries. As raw material, a real and heterogeneous organic waste from urban solid wastes was used. In the first experimental phase, seed selection was achieved through an evaluation of three different anaerobic sludges coming from wastewater treatment plants. The methanization potential of these sludges was assessed in three different batch digesters of 500 mL, at two temperature levels. The results showed that by increasing the temperature to 15 degrees C above room temperature, the methane production increases to three times. So, the best results were obtained in the digester fed with a mixed sludge, working at mesophilic conditions (38-40 degrees C). Then, this selected seed was used at the next experimental phase, testing at different digestion times (DT) of 25, 20 and 18 days in a bigger batch digester of 20 L with a reaction volume of 13 L. The conversion rates were registered at the lowest DT (18 days), reaching 44.9 L/kg(-1) of wet wasteday(-1). Moreover, DT also has a strong influence over COD removal, because there is a direct relationship between solids removal inside the reactor and DT.

  14. Increased bactericidal activity of colistin on Pseudomonas aeruginosa biofilms in anaerobic conditions.

    PubMed

    Kolpen, Mette; Appeldorff, Cecilie F; Brandt, Sarah; Mousavi, Nabi; Kragh, Kasper N; Aydogan, Sevtap; Uppal, Haleema A; Bjarnsholt, Thomas; Ciofu, Oana; Høiby, Niels; Jensen, Peter Ø

    2016-02-01

    Tolerance towards antibiotics of Pseudomonas aeruginosa biofilms is recognized as a major cause of therapeutic failure of chronic lung infection in cystic fibrosis (CF) patients. This lung infection is characterized by antibiotic-tolerant biofilms in mucus with zones of O2 depletion mainly due to polymorphonuclear leukocytic activity. In contrast to the main types of bactericidal antibiotics, it has not been possible to establish an association between the bactericidal effects of colistin and the production of detectable levels of OH ˙ on several strains of planktonic P. aeruginosa. Therefore, we propose that production of OH ˙ may not contribute significantly to the bactericidal activity of colistin on P. aeruginosa biofilm. Thus, we investigated the effect of colistin treatment on biofilm of wild-type PAO1, a catalase-deficient mutant (ΔkatA) and a colistin-resistant CF isolate cultured in microtiter plates in normoxic- or anoxic atmosphere with 1 mM nitrate. The killing of bacteria during colistin treatment was measured by CFU counts, and the OH⋅ formation was measured by 3(')-(p-hydroxylphenyl fluorescein) fluorescein (HPF) fluorescence. Validation of the assay was done by hydrogen peroxide treatment. OH⋅ formation was undetectable in aerobic PAO1 biofilms during 3 h of colistin treatment. Interestingly, we demonstrate increased susceptibility of P. aeruginosa biofilms towards colistin during anaerobic conditions. In fact, the maximum enhancement of killing by anaerobic conditions exceeded 2 logs using 4 mg L(-1) of colistin compared to killing at aerobic conditions. © FEMS 2015.

  15. Increased bactericidal activity of colistin on Pseudomonas aeruginosa biofilms in anaerobic conditions

    PubMed Central

    Kolpen, Mette; Appeldorff, Cecilie F.; Brandt, Sarah; Mousavi, Nabi; Kragh, Kasper N.; Aydogan, Sevtap; Uppal, Haleema A.; Bjarnsholt, Thomas; Ciofu, Oana; Høiby, Niels; Jensen, Peter Ø.

    2015-01-01

    Tolerance towards antibiotics of Pseudomonas aeruginosa biofilms is recognized as a major cause of therapeutic failure of chronic lung infection in cystic fibrosis (CF) patients. This lung infection is characterized by antibiotic-tolerant biofilms in mucus with zones of O2 depletion mainly due to polymorphonuclear leukocytic activity. In contrast to the main types of bactericidal antibiotics, it has not been possible to establish an association between the bactericidal effects of colistin and the production of detectable levels of OH ˙ on several strains of planktonic P. aeruginosa. Therefore, we propose that production of OH ˙ may not contribute significantly to the bactericidal activity of colistin on P. aeruginosa biofilm. Thus, we investigated the effect of colistin treatment on biofilm of wild-type PAO1, a catalase-deficient mutant (ΔkatA) and a colistin-resistant CF isolate cultured in microtiter plates in normoxic- or anoxic atmosphere with 1 mM nitrate. The killing of bacteria during colistin treatment was measured by CFU counts, and the OH⋅ formation was measured by 3′-(p-hydroxylphenyl fluorescein) fluorescein (HPF) fluorescence. Validation of the assay was done by hydrogen peroxide treatment. OH⋅ formation was undetectable in aerobic PAO1 biofilms during 3 h of colistin treatment. Interestingly, we demonstrate increased susceptibility of P. aeruginosa biofilms towards colistin during anaerobic conditions. In fact, the maximum enhancement of killing by anaerobic conditions exceeded 2 logs using 4 mg L−1 of colistin compared to killing at aerobic conditions. PMID:26458402

  16. Continuous high-solids anaerobic co-digestion of organic solid wastes under mesophilic conditions

    SciTech Connect

    Kim, Dong-Hoon; Oh, Sae-Eun

    2011-09-15

    Highlights: > High-solids (dry) anaerobic digestion is attracting a lot of attention these days. > One reactor was fed with food waste (FW) and paper waste. > Maximum biogas production rate of 5.0 m{sup 3}/m{sup 3}/d was achieved at HRT 40 d and 40% TS. > The other reactor was fed with FW and livestock waste (LW). > Until a 40% LW content increase, the reactor exhibited a stable performance. - Abstract: With increasing concerns over the limited capacity of landfills, conservation of resources, and reduction of CO{sub 2} emissions, high-solids (dry) anaerobic digestion of organic solid waste (OSW) is attracting a great deal of attention these days. In the present work, two dry anaerobic co-digestion systems fed with different mixtures of OSW were continuously operated under mesophilic conditions. Dewatered sludge cake was used as a main seeding source. In reactor (I), which was fed with food waste (FW) and paper waste (PW), hydraulic retention time (HRT) and solid content were controlled to find the maximum treatability. At a fixed solid content of 30% total solids (TS), stable performance was maintained up to an HRT decrease to 40 d. However, the stable performance was not sustained at 30 d HRT, and hence, HRT was increased to 40 d again. In further operation, instead of decreasing HRT, solid content was increased to 40% TS, which was found to be a better option to increase the treatability. The biogas production rate (BPR), CH{sub 4} production yield (MPY) and VS reduction achieved in this condition were 5.0 m{sup 3}/m{sup 3}/d, 0.25 m{sup 3} CH{sub 4}/g COD{sub added}, and 80%, respectively. Reactor (II) was fed with FW and livestock waste (LW), and LW content was increased during the operation. Until a 40% LW content increase, reactor (II) exhibited a stable performance. A BPR of 1.7 m{sup 3}/m{sup 3}/d, MPY of 0.26 m{sup 3} CH{sub 4}/g COD{sub added}, and VS reduction of 72% was achieved at 40% LW content. However, when the LW content was increased to 60

  17. Continuous high-solids anaerobic co-digestion of organic solid wastes under mesophilic conditions.

    PubMed

    Kim, Dong-Hoon; Oh, Sae-Eun

    2011-01-01

    With increasing concerns over the limited capacity of landfills, conservation of resources, and reduction of CO(2) emissions, high-solids (dry) anaerobic digestion of organic solid waste (OSW) is attracting a great deal of attention these days. In the present work, two dry anaerobic co-digestion systems fed with different mixtures of OSW were continuously operated under mesophilic conditions. Dewatered sludge cake was used as a main seeding source. In reactor (I), which was fed with food waste (FW) and paper waste (PW), hydraulic retention time (HRT) and solid content were controlled to find the maximum treatability. At a fixed solid content of 30% total solids (TS), stable performance was maintained up to an HRT decrease to 40 d. However, the stable performance was not sustained at 30 d HRT, and hence, HRT was increased to 40 d again. In further operation, instead of decreasing HRT, solid content was increased to 40% TS, which was found to be a better option to increase the treatability. The biogas production rate (BPR), CH(4) production yield (MPY) and VS reduction achieved in this condition were 5.0m(3)/m(3)/d, 0.25 m(3) CH(4)/g COD(added), and 80%, respectively. Reactor (II) was fed with FW and livestock waste (LW), and LW content was increased during the operation. Until a 40% LW content increase, reactor (II) exhibited a stable performance. A BPR of 1.7 m(3)/m(3)/d, MPY of 0.26 m(3) CH(4)/g COD(added), and VS reduction of 72% was achieved at 40% LW content. However, when the LW content was increased to 60%, there was a significant performance drop, which was attributed to free ammonia inhibition. The performances in these two reactors were comparable to the ones achieved in the conventional wet digestion and thermophilic dry digestion processes. Copyright © 2011 Elsevier Ltd. All rights reserved.

  18. Molecular Dynamics Simulation and Analysis of Interfacial Water at Selected Sulfide Mineral Surfaces under Anaerobic Conditions

    SciTech Connect

    Jin, Jiaqi; Miller, Jan D.; Dang, Liem X.

    2014-04-10

    In this paper, we report on a molecular dynamics simulation (MDS) study of the behavior of interfacial water at selected sulfide mineral surfaces under anaerobic conditions. The study revealed the interfacial water structure and wetting characteristics of the pyrite (100) surface, galena (100) surface, chalcopyrite (012) surface, sphalerite (110) surface, and molybdenite surfaces (i.e., the face, armchair-edge, and zigzag-edge surfaces), including simulated contact angles, relative number density profiles, water dipole orientations, hydrogen-bonding, and residence times. For force fields of the metal and sulfur atoms in selected sulfide minerals used in the MDS, we used the universal force field (UFF) and another set of force fields optimized by quantum chemical calculations for interactions with interfacial water molecules at selected sulfide mineral surfaces. Simulation results for the structural and dynamic properties of interfacial water molecules indicate the natural hydrophobic character for the selected sulfide mineral surfaces under anaerobic conditions as well as the relatively weak hydrophobicity for the sphalerite (110) surface and two molybdenite edge surfaces. Part of the financial support for this study was provided by the U.S. Department of Energy (DOE) under Basic Science Grant No. DE-FG-03-93ER14315. The Division of Chemical Sciences, Geosciences, and Biosciences, Office of Basic Energy Sciences (BES), of the DOE, funded work performed by Liem X. Dang. Battelle operates Pacific Northwest National Laboratory for DOE. The calculations were carried out using computer resources provided by BES. The authors are grateful to Professor Tsun-Mei Chang for valuable discussions.

  19. pH-Dependent Uptake of Fumaric Acid in Saccharomyces cerevisiae under Anaerobic Conditions

    PubMed Central

    Jamalzadeh, Elaheh; Verheijen, Peter J. T.; Heijnen, Joseph J.

    2012-01-01

    Microbial production of C4 dicarboxylic acids from renewable resources has gained renewed interest. The yeast Saccharomyces cerevisiae is known as a robust microorganism and is able to grow at low pH, which makes it a suitable candidate for biological production of organic acids. However, a successful metabolic engineering approach for overproduction of organic acids requires an incorporation of a proper exporter to increase the productivity. Moreover, low-pH fermentations, which are desirable for facilitating the downstream processing, may cause back diffusion of the undissociated acid into the cells with simultaneous active export, thereby creating an ATP-dissipating futile cycle. In this work, we have studied the uptake of fumaric acid in S. cerevisiae in carbon-limited chemostat cultures under anaerobic conditions. The effect of the presence of fumaric acid at different pH values (3 to 5) has been investigated in order to obtain more knowledge about possible uptake mechanisms. The experimental results showed that at a cultivation pH of 5.0 and an external fumaric acid concentration of approximately 0.8 mmol · liter−1, the fumaric acid uptake rate was unexpectedly high and could not be explained by diffusion of the undissociated form across the plasma membrane alone. This could indicate the presence of protein-mediated import. At decreasing pH levels, the fumaric acid uptake rate was found to increase asymptotically to a maximum level. Although this observation is in accordance with protein-mediated import, the presence of a metabolic bottleneck for fumaric acid conversion under anaerobic conditions could not be excluded. PMID:22113915

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

    PubMed Central

    Reighard, Katelyn P.

    2015-01-01

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

  1. Dynamics of brominated flame retardants removal in contaminated wastewater sewage sludge under anaerobic conditions.

    PubMed

    Stiborova, Hana; Vrkoslavova, Jana; Pulkrabova, Jana; Poustka, Jan; Hajslova, Jana; Demnerova, Katerina

    2015-11-15

    Disposal of solid waste to landfills from waste water sewage treatment plants (WWTPs) serves as a potential source of contamination by polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCD). Native microbial communities have been found to degrade a variety of xenobiotics, such as PBDEs and HBCDs. This study investigates the potential of autochthonous microflora to remove 11 PBDE congeners and HBCDs in waste water sludge under anaerobic conditions. Laboratory microcosms were constructed with sewage sludge from the WWTPs of Hradec Kralove and Brno. BDE 209 was detected as the prevailing congener in concentrations 685 and 1403 ng/g dw and the total amounts of 10 lower PBDEs (BDE 28, 47, 49, 66, 85, 99, 100, 153, 154, 183) were 605 and 205 ng/g dw in sludge from Hradec Kralove and Brno, respectively. The levels of HBCD were detected in both sludge lower than 24 ng/g dw. The experiment was carried out for 15 months. After three months of incubation, HBCD was completely degraded to below detection limits. In sewage from both WWTPs, the higher brominated DEs were removed faster than the lower brominated congeners. One exception was tri-BDE, which was degraded completely within 15 months of cultivation. A significant increase in congener tetra-BDE 49 concentrations was observed over the course of the experiment in all tested sewage. The relative distribution of individual congeners among all PBDEs changed after 15 months of the incubation in favour of lower brominated congeners. This indicates that debromination is the major mechanism of anaerobic biodegradation. Despite of the increase of BDE 49, the overall removal of all 11 PBDEs achieved the levels of 47.4 and 68.7% in samples from WWTPs Hradec Kralove and Brno, respectively.

  2. Reductive Disslocation of Pu(IV) by Clostridium sp. Under Anaerobic Conditions

    SciTech Connect

    Francis,A.; Dodge, C.; Gillow, J.

    2008-01-01

    An anaerobic, gram positive, spore-forming bacterium Clostridium sp., common in soils and wastes, capable of reduction of Fe(III) to Fe(II), Mn(IV) to Mn(II), Tc(VII) to Tc(IV), and U(VI) to U(IV), reduced Pu(IV) to Pu(III). Addition of 242Pu (IV)-nitrate to the bacterial growth medium at pH 6.4 resulted in the precipitation of Pu as amorphous Pu(OH)4 due to hydrolysis and polymerization reactions. The Pu (1 x 10-5 M) had no effect upon growth of the bacterium as evidenced by glucose consumption; carbon dioxide and hydrogen production; a decrease in pH of the medium from 6.4 to 3.0 due to production of acetic and butyric acids from glucose fermentation; and a change in the Eh of the culture medium from +50 to -180 mV. Commensurate with bacterial growth, Pu was rapidly solubilized as evidenced by an increase in Pu concentration in solution which passed through a 0.03 {mu}m filtration. Selective solvent extraction of the culture by thenoyltrifluoroacetone (TTA) indicated the presence of a reduced Pu species in the soluble fraction. X-ray absorption near edge spectroscopic (XANES) analysis of Pu in the culture sample at the Pu LIII absorption edge (18.054 keV) showed a shift of -3 eV compared to a Pu(IV) standard indicating reduction of Pu(IV) to Pu(III). These results suggest that, although Pu generally exists as insoluble Pu(IV) in the environment, under appropriate conditions, anaerobic microbial activity could affect the long-term stability and mobility of Pu by its reductive dissolution.

  3. Effect of micro-aeration on anaerobic digestion of primary sludge under septic tank conditions.

    PubMed

    Diak, James; Örmeci, Banu; Kennedy, Kevin J

    2013-04-01

    Micro-aeration, which refers to the addition of very small amounts of air, is a simple technology that can potentially be incorporated in septic tanks to improve the digestion performance. The purpose of this study was to investigate and compare the effects of micro-aeration on anaerobic digestion of primary sludge under septic tank conditions. 1.6 L batch reactor experiments were carried out in duplicate using raw primary sludge, with 4.1 % total solids, and diluted primary sludge, with 2.1 % total solids. Reactors were operated for 5 weeks at room temperature to simulate septic tank conditions. Micro-aeration rate of 0.00156 vvm effectively solubilised chemical oxygen demand (COD) and improved the subsequent degradation of COD. Micro-aeration also increased the generation of ammonia and soluble proteins, but did not improve the reduction in total and volatile solids, or the reduction in carbohydrates. Experiments using diluted sludge samples showed similar trends as the experiments with raw sludge, which suggest that initial solids concentration did not have a significant effect on the degradation of primary sludge under septic tank conditions.

  4. Chemical Changes during Anaerobic Decomposition of Hardwood, Softwood, and Old Newsprint under Mesophilic and Thermophilic Conditions

    Treesearch

    Florentino B. De la Cruz; Daniel J. Yelle; Hanna S. Gracz; Morton A. Barlaz

    2014-01-01

    The anaerobic decomposition of plant biomass is an important aspect of global organic carbon cycling. While the anaerobic metabolism of cellulose and hemicelluloses to methane and carbon dioxide are well-understood, evidence for the initial stages of lignin decomposition is fragmentary. The objective of this study was to look for evidence of chemical transformations of...

  5. Experimental evidence for growth advantage and metabolic shift stimulated by photophosphorylation of proteorhodopsin expressed in Escherichia coli at anaerobic condition.

    PubMed

    Wang, Ying; Li, Yan; Xu, Tuan; Shi, Zhenyu; Wu, Qiong

    2015-05-01

    Since solar light energy is the source of all renewable biological energy, the direct usage of light energy by bacterial cell factory has been a very attractive concept, especially using light energy to promote anaerobic fermentation growth and even recycle low-energy carbon source when energy is the limiting factor. Proteorhodopsin(PR), a light-driven proton pump proven to couple with ATP synthesis when expressed heterogeneously, is an interesting and simple option to enable light usage in engineered strains. However, although it was reported to influence fermentation in some cases, heterogeneous proteorhodopsin expression was never shown to support growth advantage or cause metabolic shift by photophosphorylation so far. Hereby, we presented the first experimental evidence that heterogeneously expressed proteorhodopsin can provide growth advantage and cause ATP-dependent metabolism shift of acetate and lactate changes in Escherichia coli at anaerobic condition. Those discoveries suggest further application potential of PR in anaerobic fermentation where energy is a limiting factor.

  6. Changes in microbial community structures due to varying operational conditions in the anaerobic digestion of oxytetracycline-medicated cow manure.

    PubMed

    Turker, Gokhan; Aydin, Sevcan; Akyol, Çağrı; Yenigun, Orhan; Ince, Orhan; Ince, Bahar

    2016-07-01

    Management of manure containing veterinary antibiotics is a major concern in anaerobic treatment systems because of their possible adverse effects on microbial communities. Therefore, the aim of study was to investigate how oxytetracycline (OTC) influences bacteria and acetoclastic and hydrogenotrophic methanogens under varying operational conditions in OTC-medicated and non-medicated anaerobic cow manure digesters. Concentrations of OTC and its metabolites throughout the anaerobic digestion were determined using ultraviolet-high-performance liquid chromatography (UV-HPLC) and tandem liquid chromatography-mass spectrometry (LC/MS/MS), respectively. Fluorescent in situ hybridization, denaturing gradient gel electrophoresis, cloning, and sequencing analyses were used to monitor changes in microbial community structures. According to the results of analytical and molecular approaches, operating conditions highly influence active microbial community dynamics and associate with biogas production and elimination of OTC and its metabolites during anaerobic digestion of cow manure in the presence of an average initial concentration of 2.2 mg OTC/L. The impact of operating conditions has a drastic effect on acetoclastic methanogens than hydrogenotrophic methanogens and bacteria.

  7. Anaerobic aquifer transformations of 2,4-Dinitrophenol under different terminal electron accepting conditions

    USGS Publications Warehouse

    Krumholz, L.R.; Suflita, J.M.

    1997-01-01

    We evaluated the susceptibility of 2,4-dinitrophenol (2,4-DNP) and 2,4-diaminophenol to anaerobic biodegradation in aquifer slurries. Aquifer microorganisms depleted 2,4-DNP at rates of 25, 9 and 0.4 μM/day under methanogenic, sulfate-reducing and nitrate-reducing conditions, respectively. Rates of abiotic, 2,4-DNP loss in autoclaved control incubations were 7.2, 6.2 and 0.95 μM/day respectively. Abiotic, 2,4-DNP reduction was especially important as the first step in its transformation. 2-Amino-4-nitrophenol was produced by this process, but this compound was further metabolized in methanogenic and sulfate-reducing aquifer slurries. This partially reduced compound persisted in autoclaved controls and in the nitrate-reducing aquifer slurries. Aquifer slurries incubated with either 2,4-DNP or 2,4-diaminophenol produced methane when incubated with no other electron acceptor suggesting that mineralization had occurred under these conditions. In parallel experiments, aquifer slurries amended with 2,6-dinitrophenol or picric acid did not produce methane at levels above the substrate unamended controls.

  8. Anaerobic biodegradation of soybean biodiesel and diesel blends under methanogenic conditions.

    PubMed

    Wu, Shuyun; Yassine, Mohamad H; Suidan, Makram T; Venosa, Albert D

    2015-12-15

    Biotransformation of soybean biodiesel and the inhibitory effect of petrodiesel were studied under methanogenic conditions. Biodiesel removal efficiency of more than 95% was achieved in a chemostat with influent biodiesel concentrations up to 2.45 g/L. The kinetics of anaerobic biodegradation of soybean biodiesel B100 (biodiesel only) with different petrodiesel loads was studied using biomass pre-acclimated to B100 and B80 (80% biodiesel and 20% petrodiesel). The results indicated that the biodiesel fraction of the blend could be effectively biodegraded, whereas petrodiesel was not biodegraded at all under methanogenic conditions. The presence of petrodiesel in blends with biodiesel had a greater inhibitory effect on the rate of biodegradation than the biodegradation efficiency (defined as the efficiency of methane production). Both the biodegradation rate coefficient and the methane production efficiency increased almost linearly with the increasing fraction of biodiesel. With the increasing fraction of petrodiesel, the biodegradation rate and efficiency were correlated with the concentration of soluble FAMEs in the water.

  9. Biofilm formation, phenotypic production of cellulose and gene expression in Salmonella enterica decrease under anaerobic conditions.

    PubMed

    Lamas, A; Miranda, J M; Vázquez, B; Cepeda, A; Franco, C M

    2016-12-05

    Salmonella enterica subsp. enterica is one of the main food-borne pathogens. This microorganism combines an aerobic life outside the host with an anaerobic life within the host. One of the main concerns related to S. enterica is biofilm formation and cellulose production. In this study, biofilm formation, morphotype, cellulose production and transcription of biofilm and quorum sensing-related genes of 11 S. enterica strains were tested under three different conditions: aerobiosis, microaerobiosis, and anaerobiosis. The results showed an influence of oxygen levels on biofilm production. Biofilm formation was significantly higher (P<0.05) in aerobiosis than in microaerobiosis and anaerobiosis. Cellulose production and RDAR (red, dry, and rough) were expressed only in aerobiosis. In microaerobiosis, the strains expressed the SAW (smooth and white) morphotype, while in anaerobiosis the colonies appeared small and red. The expression of genes involved in cellulose synthesis (csgD and adrA) and quorum sensing (sdiA and luxS) was reduced in microaerobiosis and anaerobiosis in all S. enterica strains tested. This gene expression levels were less reduced in S. Typhimurium and S. Enteritidis compared to the tested serotypes. There was a relationship between the expression of biofilm and quorum sensing-related genes. Thus, the results from this study indicate that biofilm formation and cellulose production are highly influenced by atmospheric conditions. This must be taken into account as contamination with these bacteria can occur during food processing under vacuum or modified atmospheres.

  10. A statistical method for enhancing the production of succinic acid from Escherichia coli under anaerobic conditions.

    PubMed

    Isar, Jasmine; Agarwal, Lata; Saran, Saurabh; Saxena, Rajendra Kumar

    2006-09-01

    The most influential parameters for succinic acid production obtained through one at a time method were sucrose, tryptone, magnesium carbonate, inoculum size and incubation period. These resulted in the production of 7.0 g L(-1) of succinic acid in 60 h from Escherichia coli W3110 under anaerobic conditions. Based on these results, a statistical method, face centered central composite design (FCCCD) falling under response surface method (RSM) was employed for further enhancing the succinic acid production and to monitor the interactive effect of these parameters, which resulted in a twofold increase in yield (14.3 g L(-1) in 48 h). The analysis of variance (ANOVA) showed the adequacy of the model and the verification experiments confirmed its validity. On subsequent scale-up in a 10-L bioreactor using conditions optimized through RSM, 24.2 g L(-1) of succinic acid was obtained in 30 h. This clearly indicated that the model stood valid even on large-scale. Thus, the statistical optimization strategy led to a 3.5-fold increase in the yield of succinic acid. This is the first report on the use of FCCCD to improve succinic acid production from E. coli.

  11. Anaerobic degradation of toluene and xylene by aquifer microorganisms under sulfate-reducing conditions.

    PubMed Central

    Edwards, E A; Wills, L E; Reinhard, M; Grbić-Galić, D

    1992-01-01

    Toluene and the three isomers of xylene were completely mineralized to CO2 and biomass by aquifer-derived microorganisms under strictly anaerobic conditions. The source of the inoculum was gasoline-contaminated sediment from Seal Beach, Calif. Evidence confirming that sulfate was the terminal electron acceptor is presented. Benzene and ethylbenzene were not degraded under the experimental conditions used. Successive transfers of the mixed cultures that were enriched from aquifer sediments retained the ability to degrade toluene and xylenes. Greater than 90% of 14C-labeled toluene or 14C-labeled o-xylene was mineralized to 14CO2. The doubling time for the culture grown on toluene or m-xylene was about 20 days, and the cell yield was about 0.1 to 0.14 g of cells (dry weight) per g of substrate. The accumulation of sulfide in the cultures as a result of sulfate reduction appeared to inhibit degradation of aromatic hydrocarbons. PMID:1575482

  12. Dissolution and Mobilization of Uranium in a Reduced Sediment by Natural Humic Substances under Anaerobic Conditions

    SciTech Connect

    Gu, Baohua; Luo, Wensui

    2009-01-01

    Biological reduction and precipitation of uranium (U) has been proposed as a remedial option for immobilizing uranium at contaminated sites, but the long-term stability and mobility of uranium remain a concern because it is neither removed nor destroyed. In this study, the dissolution and mobilization of reduced and oxidized forms of uranium [U(IV) and U(VI)] by natural humic substances were investigated in batch and column flow systems using a bioreduced sediment containing both U(IV) and U(VI). The addition of humic substances significantly increased the dissolution of U(IV) under anaerobic conditions. Humic acid (HA) was found to be more effective than fulvic acid (FA) in dissolving U(IV) in either 1 mM KCl or KHCO3 background solution. However, more U(VI) was dissolved in 1 mM KHCO3 than in 1 mM KCl background electrolytes. The HA also was found to be more effective than FA in mobilizing uranium under reducing and column flow conditions, although an accumulative amount of eluted U(VI) and U(IV) was relatively low (<60 g) after leaching with ~97 pore volumes of the humic solution in 1 mM KHCO3. These observations suggest that natural humic substances could potentially influence the long-term stability of bioreduced U(IV) even under strong reducing environments.

  13. 6:2 and 8:2 fluorotelomer alcohol anaerobic biotransformation in digester sludge from a WWTP under methanogenic conditions.

    PubMed

    Zhang, Shu; Szostek, Bogdan; McCausland, Patricia K; Wolstenholme, Barry W; Lu, Xiaoxia; Wang, Ning; Buck, Robert C

    2013-05-07

    6:2 FTOH and 8:2 FTOH [FTOHs, F(CF2)nCH2CH2OH, n = 6, 8] are the principal polyfluorinated raw materials used to manufacture FTOH-based products, which may be released to WWTPs during their product life cycle. For the first time, anaerobic biotransformation of FTOHs and key biotransformation intermediates in WWTP digester sludge under methanogenic conditions was investigated. 6:2 FTOH was transformed to 6:2 FTCA, [F(CF2)6CH2COOH, 32-43 mol %], 6:2 FTUCA [F(CF2)5CF═CHCOOH, 1.8-8.0 mol %], and 5:3 acid [F(CF2)5CH2CH2COOH, 18-23 mol %] by day 90 and day 176 in two separate studies. 8:2 FTOH was transformed by day 181 to 8:2 FTCA (18 mol %), 8:2 FTUCA (5.1 mol %), and 7:3 acid (27 mol %). 6:2 and 8:2 FTOH anaerobic biotransformation led to low levels of perfluorohexanoic acid (PFHxA, ≤0.4 mol %) and perfluorooctanoic acid (PFOA, 0.3 mol %), respectively. 6:2 FTUCA anaerobic biotransformation led to a newly identified novel transient intermediate 3-fluoro 5:3 acid [F(CF2)5CFHCH2COOH] and 5:3 acid, but not 5:2 sFTOH [F(CF2)5CH(OH)CH3] and α-OH 5:3 acid [F(CF2)5CH2CH(OH)COOH], two precursors leading to PFPeA (perfluoropentanoic acid) and PFHxA. Thus, FTOH anaerobic biotransformation pathways operated by microbes in the environment was likely inefficient at shortening carbon chains of FTOHs to form PFCAs (perfluorinated carboxylic acids). These results imply that anaerobic biotransformation of FTOH-based products may produce polyfluorinated acids, but is not likely a major source of PFCAs detected in anaerobic environmental matrices such as anaerobic digester sludge, landfill leachate, and anaerobic sediment under methanogenic conditions.

  14. Theoretical analysis of municipal solid waste treatment by leachate recirculation under anaerobic and aerobic conditions.

    PubMed

    van Turnhout, André G; Brandstätter, Christian; Kleerebezem, Robbert; Fellner, Johann; Heimovaara, Timo J

    2017-10-07

    Long-term emissions of Municipal Solid Waste (MSW) landfills are a burden for future generations because of the required long-term aftercare. To shorten aftercare, treatment methods have to be developed that reduce long-term emissions. A treatment method that reduces emissions at a lysimeter scale is re-circulation of leachate. However, its effectiveness at the field scale still needs to be demonstrated. Field scale design can be improved by theoretical understanding of the processes that control the effectiveness of leachate recirculation treatment. In this study, the simplest and most fundamental sets of processes are distilled that describe the emission data measured during aerobic and anaerobic leachate recirculation in lysimeters. A toolbox is used to select essential processes with objective performance criteria produced by Bayesian statistical analysis. The controlling processes indicate that treatment efficiency is mostly affected by how homogeneously important reactants are spread through the MSW during treatment. A more homogeneous spread of i.e. oxygen or methanogens increases the total amount of carbon degraded. Biodegradable carbon removal is highest under aerobic conditions, however, the hydrolysis rate constant is lower which indicates that hydrolysis is not enhanced intrinsically in aerobic conditions. Controlling processes also indicate that nitrogen removal via sequential nitrification and denitrification is plausible under aerobic conditions as long as sufficient biodegradable carbon is present in the MSW. Major removal pathways for carbon and nitrogen are indicated which are important for monitoring treatment effectiveness at a field scale. Optimization strategies for field scale application of treatments are discussed. Copyright © 2017. Published by Elsevier Ltd.

  15. In vitro metabolism of rebaudioside B, D, and M under anaerobic conditions: comparison with rebaudioside A.

    PubMed

    Purkayastha, Sidd; Pugh, George; Lynch, Barry; Roberts, Ashley; Kwok, David; Tarka, Stanley M

    2014-03-01

    The hydrolysis of the steviol glycosides rebaudioside A, B, D, and M, as well as of steviolbioside (a metabolic intermediate) to steviol was evaluated in vitro using human fecal homogenates from healthy donors under anaerobic conditions. Incubation of each of the rebaudiosides resulted in rapid hydrolysis to steviol. Metabolism was complete within 24h, with the majority occurring within the first 8h. There were no clear differences in the rate or extent of metabolism of rebaudioside B, D, or M, relative to the comparative control rebaudioside A. The hydrolysis of samples containing 2.0mg/mL of each rebaudioside tended to take slightly longer than solutions containing 0.2mg/mL. There was no apparent gender differences in the amount of metabolism of any of the rebaudiosides, regardless of the concentrations tested. An intermediate in the hydrolysis of rebaudioside M to steviol, steviolbioside, was also found to be rapidly degraded to steviol. The results demonstrate that rebaudiosides B, D, and M are metabolized to steviol in the same manner as rebaudioside A. These data support the use of toxicology data available on steviol, and on steviol glycosides metabolized to steviol (i.e., rebaudioside A) to substantiate the safety of rebaudiosides B, D, and M.

  16. Juvenile roach (Rutilus rutilus) increase their anaerobic metabolism in response to copper exposure in laboratory conditions.

    PubMed

    Maes, Virginie; Betoulle, Stéphane; Jaffal, Ali; Dedourge-Geffard, Odile; Delahaut, Laurence; Geffard, Alain; Palluel, Olivier; Sanchez, Wilfried; Paris-Palacios, Séverine; Vettier, Aurélie; David, Elise

    2016-07-01

    This study aims to determine the potential impairment of cell energy synthesis processes (glycolysis and respiratory chain pathways) by copper in juvenile roach at different regulation levels by using a multi-marker approach. Juvenile roach were exposed to 0, 10, 50, and 100 µg/L of copper for 7 days in laboratory conditions. The glycolysis pathway was assessed by measuring the relative expression levels of 4 genes encoding glycolysis enzymes. The respiratory chain was studied by assessing the electron transport system and cytochrome c oxidase gene expression. Muscle mitochondria ultrastructure was studied, and antioxidant responses were measured. Furthermore, the main energy reserves-carbohydrates, lipids, and proteins-were measured, and cellular energy was evaluated by measuring ATP, ADP, AMP and IMP concentrations. This study revealed a disturbance of the cell energy metabolism due to copper exposure, with a significant decrease in adenylate energy charge in roach exposed to 10 μg/L of copper after 1 day. Moreover, ATP concentrations significantly decreased in roach exposed to 10 μg/L of copper after 1 day. This significant decrease persisted in roach exposed to 50 µg/L of copper after 7 days. AMP concentrations increased in all contaminated fish after 1 day of exposure. In parallel, the relative expression of 3 genes encoding for glycolysis enzymes increased in all contaminated fish after 1 day of copper exposure. Focusing on the respiratory chain, cytochrome c oxidase gene expression also increased in all contaminated fish at the two time-points. The activity of the electron transport system was not disturbed by copper, except in roach exposed to 100 µg/L of copper after 1 day. Copper induced a metabolic stress. Juvenile roach seemed to respond to the ensuing high energy demand by increasing their anaerobic metabolism, but the energy produced by the anaerobic metabolism is unable to compensate for the stress induced by copper after 7

  17. Enhanced anaerobic digestion of organic contaminants containing diverse microbial population by combined microbial electrolysis cell (MEC) and anaerobic reactor under Fe(III) reducing conditions.

    PubMed

    Zhang, Jingxin; Zhang, Yaobin; Quan, Xie; Chen, Shuo; Afzal, Shahzad

    2013-05-01

    Microbial electrolysis cell (MEC) devices are efficient for wastewater treatment, but its application was limited due to low anode oxidation rate. The objective of this study was to improve anode performance of a MEC combined anaerobic reactor (R1) for high concentration industrial wastewater treatment via dosing Fe(OH)3. For the first 53 days without power, the addition of Fe(OH)3 in R1 enhanced the degradation of reactive brilliant red X-3B dye and sucrose. Applying a voltage of 0.8 V in R1 resulted in a higher decolorization and COD removal through driving the redox reactions at electrodes under Fe(III)-reducing conditions. Real-time PCR and enzyme activity analysis showed that the abundance and azoreductase activity of bacteria were improved in R1. Pyrosequencing revealed that dominant populations in anode biofilm and R1 were more diverse and abundant than the common anaerobic reactor (R2), and there was a significant distinction among anode film, R1 and R2 in microbial community structure. Copyright © 2013 Elsevier Ltd. All rights reserved.

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

    PubMed

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

    2014-12-01

    Coenzyme B12 (Vitamin B12 ) is one of the most complex biomolecules and an essential cofactor required for the catalytic activity of many enzymes. Pseudomonas denitrificans synthesizes coenzyme B12 in an oxygen-dependent manner using a pathway encoded by more than 25 genes that are located in six different operons. Escherichia coli, a robust and suitable host for metabolic engineering was used to produce coenzyme B12 . These genes were cloned into three compatible plasmids and expressed heterologously in E. coli BL21 (DE3). Real-time PCR, SDS-PAGE analysis and bioassay showed that the recombinant E. coli expressed the coenzyme B12 synthetic genes and successfully produced coenzyme B12 . However, according to the quantitative determination by inductively coupled plasma-mass spectrometry, the amount of coenzyme B12 produced by the recombinant E. coli (0.21 ± 0.02 μg/g cdw) was approximately 13-fold lower than that by P. denitrificans (2.75 ± 0.22 μg/g cdw). Optimization of the culture conditions to improve the production of coenzyme B12 by the recombinant E. coli was successful, and the highest titer (0.65 ± 0.03 μg/g cdw) of coenzyme B12 was obtained. Interestingly, although the synthesis of coenzyme B12 in P. denitrificans is strictly oxygen-dependent, the recombinant E. coli could produce coenzyme B12 under anaerobic conditions. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Anaerobic hydrocarbon degradation in petroleum-contaminated harbor sediments under sulfate-reducing and artificially imposed iron-reducing conditions

    USGS Publications Warehouse

    Coates, J.D.; Anderson, R.T.; Woodward, J.C.; Phillips, E.J.P.; Lovley, D.R.

    1996-01-01

    The potential use of iron(III) oxide to stimulate in-situ hydrocarbon degradation in anaerobic petroleum-contaminated harbor sediments was investigated. Previous studies have indicated that Fe(III)-reducing bacteria (FeRB) can oxidize some electron donors more effectively than sulfate- reducing bacteria (SRB). In contrast to previous results in freshwater sediments, the addition of Fe(III) to marine sediments from San Diego Bay, CA did not switch the terminal electron-accepting process (TEAP) from sulfate reduction to Fe-(III) reduction. Addition of Fe(III) also did not stimulate anaerobic hydrocarbon oxidation. Exposure of the sediment to air [to reoxidize Fe(II) to Fe(III)] followed by anaerobic incubation of the sediments, resulted in Fe-(III) reduction as the TEAP, but contaminant degradation was not stimulated and in some instances was inhibited. The difference in the ability of FeRB to compete with the SRB in the different sediment treatments was related to relative population sizes. Although the addition of Fe(III) did not stimulate hydrocarbon degradation, the results presented here as well as other recent studies demonstrate that there may be significant anaerobic hydrocarbon degradation under sulfate-reducing conditions in harbor sediments.

  20. Sensitive and selective culture medium for detection of environmental Clostridium difficile isolates without requirement for anaerobic culture conditions.

    PubMed

    Cadnum, Jennifer L; Hurless, Kelly N; Deshpande, Abhishek; Nerandzic, Michelle M; Kundrapu, Sirisha; Donskey, Curtis J

    2014-09-01

    Effective and easy-to-use methods for detecting Clostridium difficile spore contamination would be useful for identifying environmental reservoirs and monitoring the effectiveness of room disinfection. Culture-based detection methods are sensitive for detecting C. difficile, but their utility is limited due to the requirement of anaerobic culture conditions and microbiological expertise. We developed a low-cost selective broth medium containing thioglycolic acid and l-cystine, termed C. difficile brucella broth with thioglycolic acid and l-cystine (CDBB-TC), for the detection of C. difficile from environmental specimens under aerobic culture conditions. The sensitivity and specificity of CDBB-TC (under aerobic culture conditions) were compared to those of CDBB (under anaerobic culture conditions) for the recovery of C. difficile from swabs collected from hospital room surfaces. CDBB-TC was significantly more sensitive than CDBB for recovering environmental C. difficile (36/41 [88%] versus 21/41 [51%], respectively; P = 0.006). C. difficile latex agglutination, an enzyme immunoassay for toxins A and B or glutamate dehydrogenase, and a PCR for toxin B genes were all effective as confirmatory tests. For 477 total environmental cultures, the specificity of CDBB-TC versus that of CDBB based upon false-positive yellow-color development of the medium without recovery of C. difficile was 100% (0 false-positive results) versus 96% (18 false-positive results), respectively. False-positive cultures for CDBB were attributable to the growth of anaerobic non-C. difficile organisms that did not grow in CDBB-TC. Our results suggest that CDBB-TC provides a sensitive and selective medium for the recovery of C. difficile organisms from environmental samples, without the need for anaerobic culture conditions. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

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

    PubMed

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

    2015-01-01

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

  2. Anaerobic Biodegradation Tests of Poly(lactic acid) under Mesophilic and Thermophilic Conditions Using a New Evaluation System for Methane Fermentation in Anaerobic Sludge

    PubMed Central

    Yagi, Hisaaki; Ninomiya, Fumi; Funabashi, Masahiro; Kunioka, Masao

    2009-01-01

    Anaerobic biodegradation tests of poly(lactic acid) (PLA) powder were done at the thermophilic (55 °C) and mesophilic temperature (35 °C) under aquatic conditions [total solid concentrations of the used sludge were 2.07% (at 55 °C) and 2.24% (at 35 °C)] using a newly developed evaluation system. With this system, the evolved biogas is collected in a gas sampling bag at atmospheric pressure. This method is more convenient than using a pressure transducer or inverted graduated cylinder submerged in water. PLA was degraded about 60% in 30 days, about 80% in 40 days and about 90% in 60 days at 55 °C. On the other hand, the PLA degradation started in 55 days at 35 °C and degradation rate was much slower than at 55 °C. PMID:19865521

  3. Anaerobic biodegradation tests of poly(lactic acid) under mesophilic and thermophilic conditions using a new evaluation system for methane fermentation in anaerobic sludge.

    PubMed

    Yagi, Hisaaki; Ninomiya, Fumi; Funabashi, Masahiro; Kunioka, Masao

    2009-09-02

    Anaerobic biodegradation tests of poly(lactic acid) (PLA) powder were done at the thermophilic (55 degrees C) and mesophilic temperature (35 degrees C) under aquatic conditions [total solid concentrations of the used sludge were 2.07% (at 55 degrees C) and 2.24% (at 35 degrees C)] using a newly developed evaluation system. With this system, the evolved biogas is collected in a gas sampling bag at atmospheric pressure. This method is more convenient than using a pressure transducer or inverted graduated cylinder submerged in water. PLA was degraded about 60% in 30 days, about 80% in 40 days and about 90% in 60 days at 55 degrees C. On the other hand, the PLA degradation started in 55 days at 35 degrees C and degradation rate was much slower than at 55 degrees C.

  4. Use of Response Surface Methodology to Optimize Culture Conditions for Hydrogen Production by an Anaerobic Bacterial Strain from Soluble Starch

    NASA Astrophysics Data System (ADS)

    Kieu, Hoa Thi Quynh; Nguyen, Yen Thi; Dang, Yen Thi; Nguyen, Binh Thanh

    2016-05-01

    Biohydrogen is a clean source of energy that produces no harmful byproducts during combustion, being a potential sustainable energy carrier for the future. Therefore, biohydrogen produced by anaerobic bacteria via dark fermentation has attracted attention worldwide as a renewable energy source. However, the hydrogen production capability of these bacteria depends on major factors such as substrate, iron-containing hydrogenase, reduction agent, pH, and temperature. In this study, the response surface methodology (RSM) with central composite design (CCD) was employed to improve the hydrogen production by an anaerobic bacterial strain isolated from animal waste in Phu Linh, Soc Son, Vietnam (PL strain). The hydrogen production process was investigated as a function of three critical factors: soluble starch concentration (8 g L-1 to 12 g L-1), ferrous iron concentration (100 mg L-1 to 200 mg L-1), and l-cysteine concentration (300 mg L-1 to 500 mg L-1). RSM analysis showed that all three factors significantly influenced hydrogen production. Among them, the ferrous iron concentration presented the greatest influence. The optimum hydrogen concentration of 1030 mL L-1 medium was obtained with 10 g L-1 soluble starch, 150 mg L-1 ferrous iron, and 400 mg L-1 l-cysteine after 48 h of anaerobic fermentation. The hydrogen concentration produced by the PL strain was doubled after using RSM. The obtained results indicate that RSM with CCD can be used as a technique to optimize culture conditions for enhancement of hydrogen production by the selected anaerobic bacterial strain. Hydrogen production from low-cost organic substrates such as soluble starch using anaerobic fermentation methods may be one of the most promising approaches.

  5. Biogeochemical changes induced in uranium mining waste pile samples by uranyl nitrate treatments under anaerobic conditions.

    PubMed

    Geissler, A; Merroun, M; Geipel, G; Reuther, H; Selenska-Pobell, S

    2009-06-01

    Response of the subsurface soil bacterial community of a uranium mining waste pile to treatments with uranyl nitrate over different periods of time was studied under anaerobic conditions. The fate of the added U(VI) without supplementation with electron donors was investigated as well. By using 16S rRNA gene retrieval, we demonstrated that incubation with uranyl nitrate for 4 weeks resulted in a strong reduction in and even disappearance of some of the most predominant bacterial groups of the original sample. Instead, a strong proliferation of denitrifying and uranium-resistant populations of Rahnella spp. from Gammaproteobacteria and of Firmicutes occurred. After longer incubations for 14 weeks with uranyl nitrate, bacterial diversity increased and populations intrinsic to the untreated samples such as Bacteroidetes and Deltaproteobacteria propagated and replaced the above-mentioned uranium-resistant groups. This indicated that U(VI) was immobilized. Mössbauer spectroscopic analysis revealed an increased Fe(III) reduction by increasing the incubation time from four to 14 weeks. This result signified that Fe(III) was used as an electron acceptor by the bacterial community established at the later stages of the treatment. X-ray absorption spectroscopic analysis demonstrated that no detectable amounts of U(VI) were reduced to U(IV) in the time frames of the performed experiments. The reason for this observation is possibly due to the low level of electron donors in the studied oligotrophic environment. Time-resolved laser-induced fluorescence spectroscopic analysis demonstrated that most of the added U(VI) was bound by organic or inorganic phosphate phases both of biotic origin.

  6. [Influences of humic acids on the dissimilatory iron reduction of red soil in anaerobic condition].

    PubMed

    Xu, Li-na; Li, Zhong-pei; Che, Yu-ping

    2009-01-01

    Iron oxide is abundant in red soil. Reduction and oxidation of iron oxide are important biogeochemical processes. In this paper, we reported the effects of humic acid on dissimilatory iron reduction (DISSIR) in red soil by adding glucose or humic acid (HA), under an anaerobic condition. Results indicated that DISSIR is weak for the red soil with a low content of organic matter, Glucose that act as electron donators promoted the process of DISSIR in red soil. HA added to soil solely didn't accelerate the DISSIR since it couldn't provide electron donators to microbe. However, adding of both glucose and HA promoted the DISSIR at the beginning of the incubation but then inhibited the process, which maybe caused by the effects of precipitation and adsorption of red soil. Concentrations of HA strongly affected the DISSIR, HA at low concentrations(0.20 and 0.02 g/kg) had weak effects, while HA at a high concentration (2.00 g/kg) promoted the process at the beginning and then inhibited it. HA extracted from different materials had distinct effects on the DISSIR. HA from Weathering coal of Datong in Shanxi Province (HAs), lignite of Gongxian in Henan Province (HAh) and Dianchi Lake sediment in Kunming of Yunnan Province (HAk) all promoted the DISSIR at the beginning of the incubation. However, at the end of incubation, HAk with a low aromaticity still promoted the process, while HAs and HAh with a higher aromaticity weakened the DISSIR. This may be due to the increase in adsorption of soil with the aromaticity of HA.

  7. Direct production of organic acids from starch by cell surface-engineered Corynebacterium glutamicum in anaerobic conditions

    PubMed Central

    2013-01-01

    We produced organic acids, including lactate and succinate, directly from soluble starch under anaerobic conditions using high cell-density cultures of Corynebacterium glutamicum displaying α-amylase (AmyA) from Streptococcus bovis 148 on the cell surface. Notably, reactions performed under anaerobic conditions at 35 and 40°C, which are higher than the optimal growth temperature of 30°C, showed 32% and 19%, respectively, higher productivity of the organic acids lactate, succinate, and acetate compared to that at 30°C. However, α-amylase was not stably anchored and released into the medium from the cell surface during reactions at these higher temperatures, as demonstrated by the 61% and 85% decreases in activity, respectively, from baseline, compared to the only 8% decrease at 30°C. The AmyA-displaying C. glutamicum cells retained their starch-degrading capacity during five 10 h reaction cycles at 30°C, producing 107.8 g/l of total organic acids, including 88.9 g/l lactate and 14.0 g/l succinate. The applicability of cell surface-engineering technology for the production of organic acids from biomass by high cell-density cultures of C. glutamicum under anaerobic conditions was demonstrated. PMID:24342107

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

    SciTech Connect

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

    2012-06-01

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

  9. Effect of volatile fatty acids in anaerobic conditions on viability of helminth ova (Ascaris suum) in sanitization of municipal sludge.

    PubMed

    Rojas-Oropeza, Marcelo; Hernández-Uresti, Alejandro S; Ortega-Charleston, Luis S; Cabirol, Nathalie

    2017-09-01

    The present work aimed at evaluating the effect of four different mixtures of diverse volatile fatty acids (VFAs) on the viability of helminth ova (Ascaris suum), under mesophilic (35°C) anaerobic conditions and at different incubation times, in order to reproduce the process of two-phase anaerobic digestion. The mixtures of VFAs contained acetic, propionic, butyric, valeric, and isovaleric acids, used at concentrations normally found in acidogenic anaerobic digesters. The four treatments all showed a reduction in Ascaris suum ova viability, among which Treatment III (4.2 g-acetic acid L(-1) +  2.2 g-propionic acid L(-1) + 0.6 g-valeric acid L(-1) + 0.6 g-isovaleric acid L(-1)) resulted the most efficient. We found that the full effect of VFAs on the viability loss of Ascaris suum ova in mesophilic conditions requires a minimum incubation time of 3 days. The highest efficiency in the loss of viability was observed with Treatment III and 4-day incubation. Interestingly, the proportion of acetic acid was three times as much in this treatment than in the other ones and resulted in an effect in a minimum time of 3 days. The mesophilic condition, however, was not sufficient to induce a complete loss of viability.

  10. Mechanisms of Chromium and Uranium Toxicity in Pseudomonas stutzeri RCH2 Grown under Anaerobic Nitrate-Reducing Conditions

    PubMed Central

    Thorgersen, Michael P.; Lancaster, W. Andrew; Ge, Xiaoxuan; Zane, Grant M.; Wetmore, Kelly M.; Vaccaro, Brian J.; Poole, Farris L.; Younkin, Adam D.; Deutschbauer, Adam M.; Arkin, Adam P.; Wall, Judy D.; Adams, Michael W. W.

    2017-01-01

    Chromium and uranium are highly toxic metals that contaminate many natural environments. We investigated their mechanisms of toxicity under anaerobic conditions using nitrate-reducing Pseudomonas stutzeri RCH2, which was originally isolated from a chromium-contaminated aquifer. A random barcode transposon site sequencing library of RCH2 was grown in the presence of the chromate oxyanion (Cr[VI]O42−) or uranyl oxycation (U[VI]O22+). Strains lacking genes required for a functional nitrate reductase had decreased fitness as both metals interacted with heme-containing enzymes required for the later steps in the denitrification pathway after nitrate is reduced to nitrite. Cr[VI]-resistance also required genes in the homologous recombination and nucleotide excision DNA repair pathways, showing that DNA is a target of Cr[VI] even under anaerobic conditions. The reduced thiol pool was also identified as a target of Cr[VI] toxicity and psest_2088, a gene of previously unknown function, was shown to have a role in the reduction of sulfite to sulfide. U[VI] resistance mechanisms involved exopolysaccharide synthesis and the universal stress protein UspA. As the first genome-wide fitness analysis of Cr[VI] and U[VI] toxicity under anaerobic conditions, this study provides new insight into the impact of Cr[VI] and U[VI] on an environmental isolate from a chromium contaminated site, as well as into the role of a ubiquitous protein, Psest_2088. PMID:28848534

  11. Microbial Anaerobic Ammonium Oxidation Under Iron Reducing Conditions, Alternative Electron Acceptors

    NASA Astrophysics Data System (ADS)

    Ruiz-Urigüen, M.; Jaffe, P. R.

    2015-12-01

    Autotrophic Acidimicrobiaceae-bacterium named A6 (A6), part of the Actinobacteria phylum have been linked to anaerobic ammonium (NH4+) oxidation under iron reducing conditions. These organisms obtain their energy by oxidizing NH4+ and transferring the electrons to a terminal electron acceptor (TEA). Under environmental conditions, the TEAs are iron oxides [Fe(III)], which are reduced to Fe(II), this process is known as Feammox. Our studies indicate that alternative forms of TEAs can be used by A6, e.g. iron rich clays (i.e. nontronite) and electrodes in bioelectrochemical systems such as Microbial Electrolysis Cells (MECs), which can sustain NH4+removal and A6 biomass production. Our results show that nontronite can support Feammox and promote bacterial cell production. A6 biomass increased from 4.7 x 104 to 3.9 x 105 cells/ml in 10 days. Incubations of A6 in nontronite resulted in up to 10 times more NH4+ removal and 3 times more biomass production than when ferrihydrite is used as the Fe(III) source. Additionally, Fe in nontronite can be reoxidized by aeration and A6 can reutilize it; however, Fe is still finite in the clay. In contrast, in MECs, A6 harvest electrons from NH4+ and use an anode as an unlimited TEA, as a result current is produced. We operated multiple MECs in parallel using a single external power source, as described by Call & Logan (2011). MECs were run with an applied voltage of 0.7V and different growing mediums always containing initial 5mM NH4+. Results show that current production is favored when anthraquinone-2,6-disulfonate (AQDS), an electron shuttled, is present in the medium as it facilitates the transfer of electrons from the bacterial cell to the anode. Additionally, A6 biomass increased from 1 x 104 to 9.77 x 105cells/ml in 14 days of operation. Due to Acidimicrobiaceae-bacterium A6's ability to use various TEAs, MECs represent an alternative, iron-free form, for optimized biomass production of A6 and its application in NH4

  12. Effect Of Imposed Anaerobic Conditions On Metals Release From Acid-Mine Drainage Contaminated Streambed Sediments

    EPA Science Inventory

    Remediation of streams influenced by mine-drainage may require removal and burial of metal-containing bed sediments. Burial of aerobic sediments into an anaerobic environment may release metals, such as through reductive dissolution of metal oxyhydroxides. Mining-impacted aerob...

  13. Effect Of Imposed Anaerobic Conditions On Metals Release From Acid-Mine Drainage Contaminated Streambed Sediments

    EPA Science Inventory

    Remediation of streams influenced by mine-drainage may require removal and burial of metal-containing bed sediments. Burial of aerobic sediments into an anaerobic environment may release metals, such as through reductive dissolution of metal oxyhydroxides. Mining-impacted aerob...

  14. Comparison of Sterol Import under Aerobic and Anaerobic Conditions in Three Fungal Species, Candida albicans, Candida glabrata, and Saccharomyces cerevisiae

    PubMed Central

    Zavrel, Martin; Hoot, Sam J.

    2013-01-01

    Sterol import has been characterized under various conditions in three distinct fungal species, the model organism Saccharomyces cerevisiae and two human fungal pathogens Candida glabrata and Candida albicans, employing cholesterol, the sterol of higher eukaryotes, as well as its fungal equivalent, ergosterol. Import was confirmed by the detection of esterified cholesterol within the cells. Comparing the three fungal species, we observe sterol import under three different conditions. First, as previously well characterized, we observe sterol import under low oxygen levels in S. cerevisiae and C. glabrata, which is dependent on the transcription factor Upc2 and/or its orthologs or paralogs. Second, we observe sterol import under aerobic conditions exclusively in the two pathogenic fungi C. glabrata and C. albicans. Uptake emerges during post-exponential-growth phases, is independent of the characterized Upc2-pathway and is slower compared to the anaerobic uptake in S. cerevisiae and C. glabrata. Third, we observe under normoxic conditions in C. glabrata that Upc2-dependent sterol import can be induced in the presence of fetal bovine serum together with fluconazole. In summary, C. glabrata imports sterols both in aerobic and anaerobic conditions, and the limited aerobic uptake can be further stimulated by the presence of serum together with fluconazole. S. cerevisiae imports sterols only in anaerobic conditions, demonstrating aerobic sterol exclusion. Finally, C. albicans imports sterols exclusively aerobically in post-exponential-growth phases, independent of Upc2. For the first time, we provide direct evidence of sterol import into the human fungal pathogen C. albicans, which until now was believed to be incapable of active sterol import. PMID:23475705

  15. An anaerobic field injection experiment in a landfill leachate plume, Grindsted, Denmark: 2. Deduction of anaerobic (methanogenic, sulfate-, and Fe (III)-reducing) redox conditions

    NASA Astrophysics Data System (ADS)

    Albrechtsen, Hans-JøRgen; Bjerg, Poul L.; Ludvigsen, Liselotte; Rügge, Kirsten; Christensen, Thomas H.

    1999-04-01

    Redox conditions may be environmental factors which affect the fate of the xenobiotic organic compounds. Therefore the redox conditions were characterized in an anaerobic, leachate-contaminated aquifer 15-60 m downgradient from the Grindsted Landfill, Denmark, where an field injection experiment was carried out. Furthermore, the stability of the redox conditions spatially and over time were investigated, and different approaches to deduce the redox conditions were evaluated. The redox conditions were evaluated in a set of 20 sediment and groundwater samples taken from locations adjacent to the sediment samples. Samples were investigated with respect to groundwater chemistry, including hydrogen and volatile fatty acids (VFAs) and sediment geochemistry, and bioassays were performed. The groundwater chemistry, including redox sensitive species for a large number of samples, varied over time during the experimental period of 924 days owing to variations in the leachate from the landfill. However, no indication of change in the redox environment resulting from the field injection experiment or natural variation was observed in the individual sampling points. The methane, Fe(II), hydrogen, and VFA groundwater chemistry parameters strongly indicated a Fe(III)-reducing environment. This was further supported by the bioassays, although methane production and sulfate-reduction were also observed in a few samples close to the landfill. On the basis of the calculated carbon conversion, Fe(III) was the dominant electron acceptor in the region of the aquifer, which was investigated. Because of the complexity of a landfill leachate plume, several redox processes may occur simultaneously, and an array of methods must be applied for redox characterization in such multicomponent systems.

  16. New insights into the key microbial phylotypes of anaerobic sludge digesters under different operational conditions.

    PubMed

    Hao, Liping; Bize, Ariane; Conteau, Delphine; Chapleur, Olivier; Courtois, Sophie; Kroff, Pablo; Desmond-Le Quéméner, Elie; Bouchez, Théodore; Mazéas, Laurent

    2016-10-01

    Analyses on bacterial, archaeal communities at family level and methane-production metabolism were conducted in thirteen full-scale and pilot-scale anaerobic sludge digesters. These digesters were operated at different conditions regarding solids concentration, sludge retention time, organic loading rate and feedstock composition, seeking to optimize digester capacity. Correlations between process parameters and identified microbial phylotypes were evaluated based on relative abundance of these phylotypes determined by Quantitative PCR and 16S rDNA amplicon sequencing. Results showed that, Total Solids concentration (TS), among the evaluated operational parameters, demonstrated the most positive correlation with chemical parameters (including NH3 and VFAs) and significant impact on the abundance of key microbial phylotypes regardless of other factors. Digesters were grouped into 'Higher-TS' with higher stress (TS > 44 g/L, NH3 > 90 mg/L, VFAs > 300 mg/L) and 'Lower-TS' under easier status (TS ≤ 44 g/L, NH3 < 120 mg/L, VFAs < 525 mg/L) in this study. We identified the key microbial phylotypes, i.e. the most abundant and discriminating populations, in 'Higher-TS' digesters with high biogas production rate, which were the class Clostridia, the family Methanosarcinaceae and the order Methanobacteriales. Thermoanaerobacteraceae and Syntrophomonadaceae were identified as key families of Clostridia. Methane was produced both from acetoclastic and hydrogenotrophic methanogenesis. By contrast, in 'Higher-TS' digesters with low biogas production rate, the classes Alpha-, Beta- and Gamma-proteobacteria were detected in higher percentages, of which Rhodobacteraceae, Comamonadaceae and Xanthomonadaceae were the most abundant families respectively, and Methanomicrobiales was the prevailing methanogen order. Consistently, hydrogenotrophic pathway was predominant for methanogenesis, indicating existence of syntrophic acetate oxidation in such 'high-stress', low

  17. Humic acids facilitated microbial reduction of polymeric Pu(IV) under anaerobic conditions.

    PubMed

    Xie, Jinchuan; Liang, Wei; Lin, Jianfeng; Zhou, Xiaohua; Li, Mei

    2017-08-25

    Flavins and humic substances have been extensively studied with emphasis on their ability to transfer extracellular electrons to insoluble metal oxides. Nevertheless, whether the low-solubility Pu(IV) polymers are microbially reduced to aqueous Pu(III) remains uncertain. Experiments were conducted under anaerobic and slightly alkaline conditions to study the difference between humic acids and flavins to transport extracellular electrons to Pu(IV) polymers. Our study demonstrates that Shewanella putrefaciens was unable to directly reduce polymeric Pu(IV) with a notably low reduction rate (3.4×10(-12)mol/L Pu(III)aq within 144h). The relatively high redox potential of flavins reveals the thermodynamically unfavorable reduction: Eh(PuO2(am)/Pu(3+))

  18. Two-step upflow anaerobic sludge bed system for sewage treatment under subtropical conditions with posttreatment in waste stabilization ponds.

    PubMed

    Seghezzo, Lucas; Trupiano, Aníbal P; Liberal, Viviana; Todd, Patrick G; Figueroa, María E; Gutiérrez, Marcelo A; Da Silva Wilches, Ana C; Iribarnegaray, Martín; Guerra, Raquel G; Arena, Angélica; Cuevas, Carlos M; Zeeman, Grietje; Lettinga, Gatze

    2003-01-01

    A pilot-scale sewage treatment system consisting of two upflow anaerobic sludge bed (UASB) reactors followed by five waste stabilization ponds (WSPs) in series was studied under subtropical conditions. The first UASB reactor started up in only 1 mo (stable operation, high chemical oxygen demand [COD] removal efficiency, low volatile fatty acids concentration in the effluent, alkalinity ratio above 0.7, biogas production above 0.1 Nm3/kg of CODremoved). Removal efficiencies up to 90% were obtained in the anaerobic steps at a hydraulic retention time of 6 + 4 h (80% removal in the first step). Fecal coliform removal in the whole system was 99.9999% (99.94% in anaerobic steps and 99.98% in WSPs). COD balances over UASB reactors are provided. A minimum set of data necessary to build COD balances is proposed. Intermittent sludge washout was detected in the reactors with the COD balances. Sludge washout from single-step UASB reactors should be monitored and minimized in order to ensure constant compliance with discharge standards, especially when no posttreatment is provided. The system combined high COD and fecal coliform removal efficiency with an extremely low effluent concentration, complying with discharge standards, and making it an attractive option for sewage treatment in subtropical regions.

  19. Gaseous elemental mercury emissions and CO(2) respiration rates in terrestrial soils under controlled aerobic and anaerobic laboratory conditions.

    PubMed

    Obrist, Daniel; Faïn, Xavier; Berger, Carsen

    2010-03-01

    Mercury (Hg) levels in terrestrial soils are linked to the presence of organic carbon (C). Carbon pools are highly dynamic and subject to mineralization processes, but little is known about the fate of Hg during decomposition. This study evaluated relationships between gaseous Hg emissions from soils and carbon dioxide (CO(2)) respiration under controlled laboratory conditions to assess potential losses of Hg to the atmosphere during C mineralization. Results showed a linear correlation (r(2)=0.49) between Hg and CO(2) emissions in 41 soil samples, an effect unlikely to be caused by temperature, radiation, different Hg contents, or soil moisture. Stoichiometric comparisons of Hg/C ratios of emissions and underlying soil substrates suggest that 3% of soil Hg was subject to evasion. Even minute emissions of Hg upon mineralization, however, may be important on a global scale given the large Hg pools sequestered in terrestrial soils and C stocks. We induced changes in CO(2) respiration rates and observed Hg flux responses, including inducement of anaerobic conditions by changing chamber air supply from N(2)/O(2) (80% and 20%, respectively) to pure N(2). Unexpectedly, Hg emissions almost quadrupled after O(2) deprivation while oxidative mineralization (i.e., CO(2) emissions) was greatly reduced. This Hg flux response to anaerobic conditions was lacking when repeated with sterilized soils, possibly due to involvement of microbial reduction of Hg(2+) by anaerobes or indirect abiotic effects such as alterations in soil redox conditions. This study provides experimental evidence that Hg volatilization, and possibly Hg(2+) reduction, is related to O(2) availability in soils from two Sierra Nevada forests. If this result is confirmed in soils from other areas, the implication is that Hg volatilization from terrestrial soils is partially controlled by soil aeration and that low soil O(2) levels and possibly low soil redox potentials lead to increased Hg volatilization from

  20. Factors Affecting Cis-Dichloroethene and Vinyl Chloride Biological Transformation Under Anaerobic Conditions

    DTIC Science & Technology

    2006-05-01

    the Department of Defense Strategic Environmental Research and Development Program (SERDP). The publication of this report does not indicate...ethene. Therefore, overall objectives of this project have been: • To develop a better understanding of the microorganisms, enzymes, and mechanisms...involved in anaerobic reduction of cDCE and VC, and to develop molecular probes for monitoring these processes, • To determine the kinetics involved in

  1. Inactivation of Ascaris suum and poliovirus in biosolids under thermophilic anaerobic digestion conditions.

    PubMed

    Aitken, Michael D; Sobsey, Mark D; Blauth, Kimberly E; Shehee, Mina; Crunk, Phillip L; Walters, Glenn W

    2005-08-01

    There is considerable interest in the United States in production of Class A (low pathogen content) biosolids from the treatment of municipal wastewater sludge. Current requirements imposed by the U.S. Environmental Protection Agency make it difficult for thermophilic anaerobic digestion, in its simplest process configurations, to achieve Class A status. In particular, the time-temperature requirements necessitate long batch treatment times at temperatures associated with thermophilic anaerobic digestion. The time-temperature requirements are meant to ensure extensive inactivation of helminth eggs and enteric viruses, considered to be the most heat-resistant of the relevant pathogen classes. However, data on inactivation kinetics of these pathogens at precisely controlled and well-characterized temperatures are scarce. We measured inactivation of vaccine-strain poliovirus and eggs from the helminth Ascaris suum at temperatures from 49 to 55 degrees C in a lab-scale batch reactor containing biosolids from a continuous-flow thermophilic anaerobic digester. Both microbes were inactivated rapidly, with Ascaris more resistant to inactivation than poliovirus, and the relationships between inactivation rate and temperature were steep. The Arrhenius correlation between inactivation rate and temperature over the range 49-53 degrees C is consistent with protein denaturation as the inactivation mechanism for both microbes. The least stringent of the EPA time-temperature equations for thermal processes requires batch treatment times more than 2 orders of magnitude greater than would be required for three-log reduction of Ascaris at the rates we measured, suggesting an overly conservative regulatory approach. Such a grossly conservative approach can hinder full-scale implementation of thermophilic anaerobic digestion.

  2. 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.

  3. A study of two-stage anaerobic digestion of solid potato waste using reactors under mesophilic and thermophilic conditions.

    PubMed

    Parawira, W; Murto, M; Read, J S; Mattiasson, B

    2007-11-01

    A two-stage anaerobic digestion process operated under mesophilic and thermophilic conditions was investigated for the treatment of solid potato waste to determine optimal methane yield, efficiency of operation and process stability. A solid-bed reactor was used for hydrolysis/acidification stage while an upflow anaerobic sludge blanket (UASB) reactor was used in the second stage, for methanogenesis. Three sets of conditions were investigated: (1) mesophilic + mesophilic, (II) mesophilic + thermophilic and (III) thermophilic + thermophilic in the hydrolysis/acidification and methanogenesis reactors, respectively. The methane yield was higher under mesophilic conditions (0.49 l CH4 g COD(-1)degraded) than thermophilic conditions (0.41 l CH4 g COD(-1)degraded) with reference to the methanogenic reactors. (COD)--chemical oxygen demand. However, the digestion period was shorter in systems II and III than in system I. Also, in system III the UASB reactor (thermophilic conditions) could handle a higher organic loading rate (OLR) (36 g COD 1(-1)d(-1)) than in system I (11 g COD 1(-1)d(-1)) (mesophilic conditions) with stable operation. Higher OLRs in the methanogenic reactors resulted in reactor failure due to increasing total volatile fatty acid levels. In all systems, the concentration of propionate was one of the highest, higher than acetic acid, among the volatile fatty acids in the effluent. The results show the feasibility of using a two-stage system to treat solid potato waste under both mesophilic and thermophilic conditions. If the aim is to treat solid potato waste completely within a short period of time thermophilic conditions are to be preferred, but to obtain higher methane yield mesophilic conditions are preferable and therefore there is a need to balance methane yield and complete digestion period when dealing with large quantities of solid potato waste.

  4. Macroscopic mass and energy balance of a pilot plant anaerobic bioreactor operated under thermophilic conditions.

    PubMed

    Espinosa-Solares, Teodoro; Bombardiere, John; Chatfield, Mark; Domaschko, Max; Easter, Michael; Stafford, David A; Castillo-Angeles, Saul; Castellanos-Hernandez, Nehemias

    2006-01-01

    Intensive poultry production generates over 100,000 t of litter annually in West Virginia and 9 x 10(6) t nationwide. Current available technological alternatives based on thermophilic anaerobic digestion for residuals treatment are diverse. A modification of the typical continuous stirred tank reactor is a promising process being relatively stable and owing to its capability to manage considerable amounts of residuals at low operational cost. A 40-m3 pilot plant digester was used for performance evaluation considering energy input and methane production. Results suggest some changes to the pilot plant configuration are necessary to reduce power consumption although maximizing biodigester performance.

  5. Organic intermediates in the anaerobic biodegradation of coal to methane under laboratory conditions

    USGS Publications Warehouse

    Orem, W.H.; Voytek, M.A.; Jones, E.J.; Lerch, H.E.; Bates, A.L.; Corum, M.D.; Warwick, P.D.; Clark, A.C.

    2010-01-01

    Organic intermediates in coal fluids produced by anaerobic biodegradation of geopolymers in coal play a key role in the production of methane in natural gas reservoirs. Laboratory biodegradation experiments on sub-bituminous coal from Texas, USA, were conducted using bioreactors to examine the organic intermediates relevant to methane production. Production of methane in the bioreactors was linked to acetate accumulation in bioreactor fluid. Long chain fatty acids, alkanes (C19-C36) and various low molecular weight aromatics, including phenols, also accumulated in the bioreactor fluid and appear to be the primary intermediates in the biodegradation pathway from coal-derived geopolymers to acetate and methane. ?? 2010.

  6. Optimization of microwave pretreatment conditions to maximize methane production and methane yield in mesophilic anaerobic sludge digestion.

    PubMed

    Park, W J; Ahn, J H

    2011-10-01

    The objective of this study was to find optimum microwave pretreatment conditions for methane production and methane yield in anaerobic sludge digestion. The sludge was pretreated using a laboratory-scale industrial microwave unit (2450 MHz frequency). Microwave temperature increase rate (TIR) (2.9-17.1 degrees C/min) and final temperature (FT) (52-108 degrees C) significantly affected solubilization, methane production, and methane yield. Solubilization degree (soluble chemical oxygen demand (COD)/total COD) in the pretreated sludge (3.3-14.7%) was clearly higher than that in the raw sludge (2.6%). Within the design boundaries, the optimum conditions for maximum methane production (2.02 L/L) were TIR = 9.1 degrees C/min and FT = 90 degrees C, and the optimum conditions for maximum methane yield (809 mL/g VS(removed)) were TIR 7.1 degrees C/min and FT = 92 degrees C.

  7. Degradation of glycol based aircraft deicing fluids under anaerobic methanogenic conditions

    NASA Astrophysics Data System (ADS)

    Veltman, Shawn Herbert

    2000-11-01

    Large quantities of aircraft deicing fluid (ADF) comprised mainly of ethylene glycol (EG) and propylene glycol (PG) are used for aircraft deicing/anti-icing during cold weather operations at airports throughout the world. Several different formulations of ADF have been developed and are used. Type I solutions are commonly employed to remove snow and ice from aircraft surfaces (deicing), and Type IV solutions are commonly applied to prevent ice from reforming (anti-icing). The runoff from aircraft deicing operations is known to have a high oxygen demand. As a consequence, deicing wastes are often collected at airports for treatment. ADF products also contain small amounts of colorants, corrosion inhibitors, and thickeners, and these compounds may pose a greater environmental concern than oxygen depletion. Several studies have been completed to compare the relative toxicity of the pure glycols (EG and PG) vs. ADF using Microtox RTM assays and other aquatic tests, and it has been reported that ADF is significantly more inhibitory than the pure glycols. With growing concern over the environmental consequences of deicing there has been interest in developing anaerobic technology to treat deicing waste. In this dissertation a survey, a deicing waste characterization study, and research efforts employing serum bottles and bench scale laboratory reactors were used to demonstrate that ADF may be degraded effectively and efficiently in an anaerobic methanogenic environment. The factors that may affect this degradation are examined and discussed.

  8. Biotransformation of 2,4-dinitrotoluene by obligate marine Shewanella marisflavi EP1 under anaerobic conditions.

    PubMed

    Huang, Jiexun; Ning, Guojing; Li, Feili; Sheng, G Daniel

    2015-03-01

    Anaerobic transformation of 2,4-DNT by obligate marine Shewanella marisflavi EP1 was investigated. The cell growth of EP1 was proportional to the total amount of 2,4-DNT reduced. The eventual transformation product was 2,4-diaminotoluene, via 2-amino-4-nitrotoluene and 4-amino-2-nitrotoluene as intermediates. The presence of Cu(2+), dicumarol, metyrapone and flavins intensively influenced the reduction activity of 2,4-DNT, suggesting that dehydrogenease, menaquinone, cytochromes and flavins are essentially involved in electron transport process for 2,4-DNT reduction. These results indicate that biotransformation of 2,4-DNT by EP1 is a form of microbial anaerobic respiration. Furthermore, EP1 was capable of transforming 2,4-DNT at relatively alkaline range of pH (7-9), and at a wide range of temperature (4-40°C) and salinity (2-8% NaCl concentration). Our findings not only deepen our understanding of the environmental fate of 2,4-DNT, but also provide an extension to the application of shewanellae in the site bioremediation and/or wastewater treatment. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. Biofilm dynamics and kinetics during high-rate sulfurate reduction under anaerobic conditions

    SciTech Connect

    Nielsen, P.H.

    1987-01-01

    The sulfate kinetics in an anaerobic, sulfate-reducing biofilm were investigated with an annular biofilm reactor. Biofilm growth, sulfide production, and kinetic constants (K/sub m/ and V/sub max/) for the bacterial sulfate uptake within the biofilm were determined. These parameters were used to model the biofilm kinetics, and the experimental results were in good agreement with the model predictions. Typical zero-order volume rate constants for sulfate reduction in a biofilm without substrate limitation ranged from 56 to 93 ..mu..mol of SO/sub 4//sup 2 -/ cm/sup -3/ h/sup -1/ at 20/sup 0/C. The temperature dependence (Q/sub 10/) of sulfate reduction was equivalent to 3.4 at between 9 and 20/sup 0/C. The measured rates of sulfate reduction could explain the relatively high sulfide levels found in sewers and wastewater treatment systems. Furthermore, it has been shown that sulfate reduction in biofilms just a few hundred micrometers thick is limited by sulfate diffusion into biofilm at concentrations below 0.5 mM. This observation might, in some cases, be an explanation for the relatively poor capacity of the sulfate-reducing bacteria to compete with the methanogenic bacteria in anaerobic wastewater treatment in submerged filters.

  10. Strategies for changing temperature from mesophilic to thermophilic conditions in anaerobic CSTR reactors treating sewage sludge.

    PubMed

    Bousková, A; Dohányos, M; Schmidt, J E; Angelidaki, I

    2005-04-01

    Thermophilic anaerobic digestion presents an advantageous way for stabilization of sludge from wastewater treatment plants. Two different strategies for changing operational process temperature from mesophilic (37 degrees C) to thermophilic (55 degrees C) were tested using two continuous flow stirred tank reactors operated at constant organic loading rate of 1.38 g VS/l reactor/day and hydraulic retention time of 20 days. In reactor A, the temperature was increased step-wise: 37 degrees C-->42 degrees C-->47 degrees C-->51 degrees C-->55 degrees C. While in reactor B, the temperature was changed in one-step, from 37 degrees C to the desired temperature of 55 degrees C, The results showed that the overall adaptation of the process for the step-wise temperature increment took 70 days in total and a new change was applied when the process was stabilized as indicated by stable methane production and low volatile fatty acids concentrations. Although the one-step temperature increase caused a severe disturbance in all the process parameters, the system reached a new stable operation after only 30 days indicating that this strategy is the best in changing from mesophilic to thermophilic operation in anaerobic digestion plants.

  11. Anaerobic killing of mucoid Pseudomonas aeruginosa by acidified nitrite derivatives under cystic fibrosis airway conditions

    PubMed Central

    Yoon, Sang Sun; Coakley, Ray; Lau, Gee W.; Lymar, Sergei V.; Gaston, Benjamin; Karabulut, Ahmet C.; Hennigan, Robert F.; Hwang, Sung-Hei; Buettner, Garry; Schurr, Michael J.; Mortensen, Joel E.; Burns, Jane L.; Speert, David; Boucher, Richard C.; Hassett, Daniel J.

    2006-01-01

    Mucoid, mucA mutant Pseudomonas aeruginosa cause chronic lung infections in cystic fibrosis (CF) patients and are refractory to phagocytosis and antibiotics. Here we show that mucoid bacteria perish during anaerobic exposure to 15 mM nitrite (NO2–) at pH 6.5, which mimics CF airway mucus. Killing required a pH lower than 7, implicating formation of nitrous acid (HNO2) and NO, that adds NO equivalents to cellular molecules. Eighty-seven percent of CF isolates possessed mucA mutations and were killed by HNO2 (3-log reduction in 4 days). Furthermore, antibiotic-resistant strains determined were also equally sensitive to HNO2. More importantly, HNO2 killed mucoid bacteria (a) in anaerobic biofilms; (b) in vitro in ultrasupernatants of airway secretions derived from explanted CF patient lungs; and (c) in mouse lungs in vivo in a pH-dependent fashion, with no organisms remaining after daily exposure to HNO2 for 16 days. HNO2 at these levels of acidity and NO2– also had no adverse effects on cultured human airway epithelia in vitro. In summary, selective killing by HNO2 may provide novel insights into the important clinical goal of eradicating mucoid P. aeruginosa from the CF airways. PMID:16440061

  12. Reorganization of the bacterial and archaeal populations associated with organic loading conditions in a thermophilic anaerobic digester.

    PubMed

    Hori, Tomoyuki; Haruta, Shin; Sasaki, Daisuke; Hanajima, Dai; Ueno, Yoshiyuki; Ogata, Atsushi; Ishii, Masaharu; Igarashi, Yasuo

    2015-03-01

    Organic loading conditions are an important factor influencing reactor performances in methanogenic bioreactors. Yet the underlying microbiological basis of the process stability, deterioration, and recovery remains to be understood. Here, structural responses of the bacterial and archaeal populations to the change of organic loading conditions in a thermophilic anaerobic digester were investigated by process analyses and 16S rRNA gene-based molecular approaches. The biogas was produced stably without the accumulation of volatile fatty acids (VFAs) at low organic loading rates (OLRs) in the beginning of reactor operation. Increasing OLR in stages disrupted the stable reactor performance, and high OLR conditions continued the deteriorated performance with slight biogas production and high accumulation of VFAs. Thereafter, the gradual decrease of OLR resulted in the recovery from the deterioration, giving rise to the stable performance again. The stable performances before and after the high OLR conditions conducted were associated with compositionally similar but not identical methanogenic consortia. The bacterial and archaeal populations were synchronously changed at both the transient phases toward the deteriorated performance and in recovery process, during which the dynamic shift of aceticlastic and hydrogenotrophic methanogens including the recently identified Methanomassiliicoccus might contribute to the maintenance of the methanogenic activity. The distinctive bacterial population with a high predominance of Methanobacterium formicicum as archaeal member was found for the deteriorated performance. The results in this study indicate the coordinated reorganization of the bacterial and archaeal populations in response to functional states induced by the change of organic loading conditions in the anaerobic digester. Copyright © 2014 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  13. Enrichment of acetogenic bacteria in high rate anaerobic reactors under mesophilic and thermophilic conditions.

    PubMed

    Ryan, P; Forbes, C; McHugh, S; O'Reilly, C; Fleming, G T A; Colleran, E

    2010-07-01

    The objective of the current study was to expand the knowledge of the role of acetogenic Bacteria in high rate anaerobic digesters. To this end, acetogens were enriched by supplying a variety of acetogenic growth supportive substrates to two laboratory scale high rate upflow anaerobic sludge bed (UASB) reactors operated at 37 degrees C (R1) and 55 degrees C (R2). The reactors were initially fed a glucose/acetate influent. Having achieved high operational performance and granular sludge development and activity, both reactors were changed to homoacetogenic bacterial substrates on day 373 of the trial. The reactors were initially fed with sodium vanillate as a sole substrate. Although % COD removal indicated that the 55 degrees C reactor out performed the 37 degrees C reactor, effluent acetate levels from R2 were generally higher than from R1, reaching values as high as 5023 mg l(-1). Homoacetogenic activity in both reactors was confirmed on day 419 by specific acetogenic activity (SAA) measurement, with higher values obtained for R2 than R1. Sodium formate was introduced as sole substrate to both reactors on day 464. It was found that formate supported acetogenic activity at both temperatures. By the end of the trial, no specific methanogenic activity (SMA) was observed against acetate and propionate indicating that the methane produced was solely by hydrogenotrophic Archaea. Higher SMA and SAA values against H(2)/CO(2) suggested development of a formate utilising acetogenic population growing in syntrophy with hydrogenotrophic methanogens. Throughout the formate trial, the mesophilic reactor performed better overall than the thermophilic reactor.

  14. Survival of weed seeds and animal parasites as affected by anaerobic digestion at meso- and thermophilic conditions.

    PubMed

    Johansen, Anders; Nielsen, Henrik B; Hansen, Christian M; Andreasen, Christian; Carlsgart, Josefine; Hauggard-Nielsen, Henrik; Roepstorff, Allan

    2013-04-01

    Anaerobic digestion of residual materials from animals and crops offers an opportunity to simultaneously produce bioenergy and plant fertilizers at single farms and in farm communities where input substrate materials and resulting digested residues are shared among member farms. A surplus benefit from this practice may be the suppressing of propagules from harmful biological pests like weeds and animal pathogens (e.g. parasites). In the present work, batch experiments were performed, where survival of seeds of seven species of weeds and non-embryonated eggs of the large roundworm of pigs, Ascaris suum, was assessed under conditions similar to biogas plants managed at meso- (37°C) and thermophilic (55°C) conditions. Cattle manure was used as digestion substrate and experimental units were sampled destructively over time. Regarding weed seeds, the effect of thermophilic conditions (55°C) was very clear as complete mortality, irrespective of weed species, was reached after less than 2 days. At mesophilic conditions, seeds of Avena fatua, Sinapsis arvensis, Solidago canadensis had completely lost germination ability, while Brassica napus, Fallopia convolvulus and Amzinckia micrantha still maintained low levels (~1%) of germination ability after 1 week. Chenopodium album was the only weed species which survived 1 week at substantial levels (7%) although after 11 d germination ability was totally lost. Similarly, at 55°C, no Ascaris eggs survived more than 3h of incubation. Incubation at 37°C did not affect egg survival during the first 48 h and it took up to 10 days before total elimination was reached. In general, anaerobic digestion in biogas plants seems an efficient way (thermophilic more efficient than mesophilic) to treat organic farm wastes in a way that suppresses animal parasites and weeds so that the digestates can be applied without risking spread of these pests.

  15. Rhodobacter capsulatus Catalyzes Light-Dependent Fe(II) Oxidation under Anaerobic Conditions as a Potential Detoxification Mechanism▿

    PubMed Central

    Poulain, Alexandre J.; Newman, Dianne K.

    2009-01-01

    Diverse bacteria are known to oxidize millimolar concentrations of ferrous iron [Fe(II)] under anaerobic conditions, both phototrophically and chemotrophically. Yet whether they can do this under conditions that are relevant to natural systems is understood less well. In this study, we tested how light, Fe(II) speciation, pH, and salinity affected the rate of Fe(II) oxidation by Rhodobacter capsulatus SB1003. Although R. capsulatus cannot grow photoautotrophically on Fe(II), it oxidizes Fe(II) at rates comparable to those of bacteria that do grow photoautotrophically on Fe(II) as soon as it is exposed to light, provided it has a functional photosystem. Chelation of Fe(II) by diverse organic ligands promotes Fe(II) oxidation, and as the pH increases, so does the oxidation rate, except in the presence of nitrilotriacetate; nonchelated forms of Fe(II) are also more rapidly oxidized at higher pH. Salt concentrations typical of marine environments inhibit Fe(II) oxidation. When growing photoheterotrophically on humic substances, R. capsulatus is highly sensitive to low concentrations of Fe(II); it is inhibited in the presence of concentrations as low as 5 μM. The product of Fe(II) oxidation, ferric iron, does not hamper growth under these conditions. When other parameters, such as pH or the presence of chelators, are adjusted to promote Fe(II) oxidation, the growth inhibition effect of Fe(II) is alleviated. Together, these results suggest that Fe(II) is toxic to R. capsulatus growing under strictly anaerobic conditions and that Fe(II) oxidation alleviates this toxicity. PMID:19717624

  16. Enhancement of sludge anaerobic biodegradability by combined microwave-H2O2 pretreatment in acidic conditions.

    PubMed

    Eswari, Parvathy; Kavitha, S; Kaliappan, S; Yeom, Ick-Tae; Banu, J Rajesh

    2016-07-01

    The aim of this study was to increase the sludge disintegration and reduce the cost of microwave (MW) pretreatment. Thermodynamic analysis of MW hydrolysis revealed the best fit with a first-order kinetic model at a specific energy of 18,600 kJ/kg total solids (TS). Combining H2O2 with MW resulted in a significant increment in solubilization from 30 to 50 % at 18,600 kJ/kg TS. The pH of H2O2-assisted MW-pretreated sludge (MW + H2O2) was in the alkaline range (pH 9-10), and it made the sludge unfavorable for subsequent anaerobic digestion and inhibits methane production. In order to nullify the alkaline effect caused by the MW + H2O2 combination, the addition of acid was considered for pH adjustment. H2O2-assisted MW-pretreated sludge in acidic conditions (MW + H2O2 + acid) showed a maximum methane production of 323 mL/g volatile solids (VS) than others during anaerobic biodegradability. A cost analysis of this study reveals that MW + H2O2 + acid was the most economical method with a net profit of 59.90 €/t of sludge.

  17. Reactor performance of a 750 m(3) anaerobic digestion plant: varied substrate input conditions impacting methanogenic community.

    PubMed

    Wagner, Andreas Otto; Malin, Cornelia; Lins, Philipp; Gstraunthaler, Gudrun; Illmer, Paul

    2014-10-01

    A 750 m(3) anaerobic digester was studied over a half year period including a shift from good reactor performance to a reduced one. Various abiotic parameters like volatile fatty acids (VFA) (formic-, acetic-, propionic-, (iso-)butyric-, (iso-)valeric-, lactic acid), total C, total N, NH4 -N, and total proteins, as well as the organic matter content and dry mass were determined. In addition several process parameters such as temperature, pH, retention time and input of substrate and the concentrations of CH4, H2, CO2 and H2S within the reactor were monitored continuously. The present study aimed at the investigation of the abundance of acetogens and total cell numbers and the microbial methanogenic community as derived from PCR-dHPLC analysis in order to put it into context with the determined abiotic parameters. An influence of substrate quantity on the efficiency of the anaerobic digestion process was found as well as a shift from a hydrogenotrophic in times of good reactor performance towards an acetoclastic dominated methanogenic community in times of reduced reactor performance. After the change in substrate conditions it took the methano-archaeal community about 5-6 weeks to be affected but then changes occurred quickly.

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

    PubMed

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

    2014-06-01

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

  19. Comparison of microbial communities during the anaerobic digestion of Gracilaria under mesophilic and thermophilic conditions.

    PubMed

    Azizi, Aqil; Kim, Wonduck; Lee, Jung Hyun

    2016-10-01

    Mesophilic and thermophilic anaerobic digesters (MD and TD, respectively) utilizing Gracilaria and marine sediment as the substrate and inoculum, respectively, were compared by analyzing their performances and microbial community changes. During three successive transfers, the average cumulative methane yields in the MD and TD were 222.6 ± 17.3 mL CH4/g volatile solids (VS) and 246.1 ± 11 mL CH4/g VS, respectively. The higher hydrolysis rate and acidogenesis in the TD resulted in a several fold greater accumulation of volatile fatty acids (acetate, propionate, and butyrate) followed by a larger pH drop with a prolonged recovery than in the MD. However, the operational stability between both digesters remained comparable. Pyrosequencing analyses revealed that the MD had more complex microbial diversity indices and microbial community changes than the TD. Interestingly, Methanomassiliicoccales, the seventh methanogen order was the predominant archaeal order in the MD along with bacterial orders of Clostridiales, Bacteriodales, and Synergistales. Meanwhile, Coprothermobacter and Methanobacteriales dominated the bacterial and archaeal community in the TD, respectively. Although the methane yield is comparable, both MD and TD show a different profile of pH, VFA and the microbial communities.

  20. Anaerobic co-digestion of sewage sludge and strawberry extrudate under mesophilic conditions.

    PubMed

    Serrano, Antonio; Siles, José A; Chica, Arturo F; Martín, M Ángeles

    2014-01-01

    The biomethanization of sewage sludge has several disadvantages such as low methane yield, poor biodegradability and nutrient imbalance. In this paper, a sewage sludge and strawberry extrudate mixture in a proportion of 40:60 (wet weight) is proposed to improve the viability of the process. The addition of an easily biodegradable co-substrate enhanced the nutrient balance and diluted the heavy metals and inhibitors from sewage sludge. Two different experimental set-ups at lab and semi-pilot scale were employed in order to ensure the reproducibility and significance of the obtained values. Co-digestion improved the stability of the process by decreasing the alkalinity to a mean value of 3215 ± 190 mg CaCO₃/L, while maintaining the pH within the optimal range for anaerobic digestion. The methane yield coefficient and biodegradability were 176 L/kg VS (total volatile solids) (0°C, 1 atm) and 81% (VS), respectively. Kinetic parameters decreased at the highest loads, suggesting the occurrence of a slowing down phenomenon. A quality organic amendment with a heavy metal content lower than the limits established under European legislation for agricultural applications was obtained from the digestate of the proposed treatment.

  1. Anaerobic digestion of pig and dairy manure under photo-dark fermentation condition.

    PubMed

    Yin, Dongxue; Liu, Wei; Zhai, Ningning; Yang, Gaihe; Wang, Xiaojiao; Feng, Yongzhong; Ren, Guangxin

    2014-08-01

    Anaerobic digestion (AD) with livestock manure is a promising way for biogas production. This work presents the influence of photo-dark fermentation on biogas production of pig manure (PM) and dairy manure (DM). All sets were conducted with temperature 35 ± 2 °C and total solid concentrations 8%: PM₁ and DM₁ in transparent reactor under sunlight for photo-dark fermentation, and PM₂ and DM₂ in non-transparent reactor for dark fermentation. DM₂ had the best cumulative biogas production (CBP) of 15,447.5 mL, followed by PM₁ (15,020 mL) with stable pH and low total ammonium nitrogen (TAN) concentration (1384.99 mg/L), and DM₁ and PM₂. The CBP of DM₂ was 5.77 times as much as PM₂. The relationship between CBP and four factors including volatile fatty acid (VFA), TAN, total alkalinity and pH was analyzed. pH gained the maximum determination coefficient with the CBP among all sets and total alkalinity showed negative correlation with CBP of PM₁ and DM₁.

  2. Wastewater sludges pretreated by different oxidation systems at mild conditions to promote the biogas formation in anaerobic processes.

    PubMed

    Segura, Y; Puyol, D; Ballesteros, L; Martínez, F; Melero, J A

    2016-12-01

    The effect of different oxidation processes at mild conditions including the coupled-Fenton (sono-Fenton, photo-Fenton, and sono-photo-Fenton) and their blank systems (ultrasound, ultraviolet, zero valent iron, and Fenton) on anaerobic digestion of the sludge for biogas production was investigated. Ultrasounds led to the highest organic matter solubilization (3.8 up to 5.2 g chemical oxygen demand (COD)/L, for the raw and treated sludge, respectively), while for the rest, organic matter transformation was observed resulting in an almost soluble COD net balance. Results indicated that for the most oxidative processes, the released organic matter was probably mineralized by the hydroxyl radicals produced during the treatments. It is interesting to remark that even if the biochemical methane potential was barely enhanced by the different methods applied, all the methods demonstrated to enhance the overall kinetics of the biomethanation processes, increasing the rapidly biodegradable fraction of the sludge.

  3. Partial degradation mechanisms of malachite green and methyl violet B by Shewanella decolorationis NTOU1 under anaerobic conditions.

    PubMed

    Chen, C-H; Chang, C-F; Liu, S-M

    2010-05-15

    This work demonstrated that Shewanella decolorationis NTOU1 decolorized 200 mg l(-1) of crystal violet, malachite green, or methyl violet B within 2-11h under anaerobic conditions at 35 degrees C. The initial color removal rate of malachite green was highest, while that of methyl violet was lowest. GC/MS analyses of the intermediate compounds produced during and after decolorization of malachite green and methyl violet B suggested that biodegradation of these dyes involved reduction to leuco form, N-demethylation, and reductive splitting of the triphenyl rings. The number of N-methylated groups of these dyes might have influenced decolorization rates and the reductive splitting of the triphenyl rings of these dyes. Cytotoxicity and antimicrobial test data showed that malachite green and methyl violet B solution (100 mg l(-1)) were toxic. Toxicity of the dyes decreased after their decolorization, but further incubation resulted in increased toxicity.

  4. Microcosm experiments to control anaerobic redox conditions when studying the fate of organic micropollutants in aquifer material

    NASA Astrophysics Data System (ADS)

    Barbieri, Manuela; Carrera, Jesús; Sanchez-Vila, Xavier; Ayora, Carlos; Cama, Jordi; Köck-Schulmeyer, Marianne; López de Alda, Miren; Barceló, Damià; Tobella Brunet, Joana; Hernández García, Marta

    2011-11-01

    The natural processes occurring in subsurface environments have proven to effectively remove a number of organic pollutants from water. The predominant redox conditions revealed to be one of the controlling factors. However, in the case of organic micropollutants the knowledge on this potential redox-dependent behavior is still limited. Motivated by managed aquifer recharge practices microcosm experiments involving aquifer material, settings potentially feasible in field applications, and organic micropollutants at environmental concentrations were carried out. Different anaerobic redox conditions were promoted and sustained in each set of microcosms by adding adequate quantities of electron donors and acceptors. Whereas denitrification and sulfate-reducing conditions are easily achieved and maintained, Fe- and Mn-reduction are strongly constrained by the slower dissolution of the solid phases commonly present in aquifers. The thorough description and numerical modeling of the evolution of the experiments, including major and trace solutes and dissolution/precipitation of solid phases, have been proven necessary to the understanding of the processes and closing the mass balance. As an example of micropollutant results, the ubiquitous beta-blocker atenolol is completely removed in the experiments, the removal occurring faster under more advanced redox conditions. This suggests that aquifers constitute a potentially efficient alternative water treatment for atenolol, especially if adequate redox conditions are promoted during recharge and long enough residence times are ensured.

  5. Evidence for Anaerobic Methane Oxidation Under Iron-Reducing Conditions in a Crude-Oil Contaminated Aquifer

    NASA Astrophysics Data System (ADS)

    Bekins, B. A.; Amos, R. T.; Cozzarelli, I. M.; Voytek, M. A.; Kirshtein, J.; Jones, E. J.; Delin, G. N.

    2008-12-01

    Although anaerobic methane oxidation (AMO) under iron reducing conditions is energetically feasible, its existence is still an open question. At a crude oil spill site near the town of Bemidji, MN, methanogenic degradation of entrapped oil floating at the water table has been occurring for more than 20 years. In the anaerobic portion of the hydrocarbon plume there is evidence for AMO under iron-reducing conditions between 75 m and 120 m downgradient of the oil body. In this zone, dissolved methane concentrations decrease steadily from over 0.6 mmol/L to less than 0.06 mmol/L. Decreases in dissolved methane are accompanied by an increase in δ13C-CH4 indicating that methane attenuation occurs through microbially mediated oxidation. The dissolved methane decrease of ~0.5 mmol/L occurs where dissolved sulfate is below 0.06 mmol/L, dissolved oxygen is below 3 μmol/L, and nitrate is below 0.02 mmol/L. Together these electron acceptors can account for degradation of only 0.07 mmol/L of methane. Moreover, hydrocarbon contaminants contribute an additional ~1 mmol/L total organic carbon in this area. Active iron- reduction is indicated by dissolved iron concentrations exceeding 0.15 mmol/L. To investigate the sediment bioavailable iron and microbial populations, 2-m-long cores were collected at four locations spaced 15 m horizontally and sampled at 50-cm-depth intervals. Values of bioavailable Fe(III) averaged 8 mmol/kg (n=16), which is over eight times the amount required to degrade 0.5 mmol/L methane. Geobacter detected by qPCR averaged over 2,600/g, while sulfate reducing bacteria were detected in only four samples with 100/g being the highest abundance measured. Laboratory incubations were performed with eight sediment samples from these cores. For each location, 1 g of sediment was added to 10 mL anaerobic medium and amended with amorphous FeOOH, Fe(III)NTA, sulfate, or nitrate. Loss of methane occurred in 33% of the iron-amended treatments, 25% of the nitrate

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

    PubMed Central

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

    2015-01-01

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

  7. The metabolic costs of improving ethanol yield by reducing glycerol formation capacity under anaerobic conditions in Saccharomyces cerevisiae

    PubMed Central

    2013-01-01

    Background Finely regulating the carbon flux through the glycerol pathway by regulating the expression of the rate controlling enzyme, glycerol-3-phosphate dehydrogenase (GPDH), has been a promising approach to redirect carbon from glycerol to ethanol and thereby increasing the ethanol yield in ethanol production. Here, strains engineered in the promoter of GPD1 and deleted in GPD2 were used to investigate the possibility of reducing glycerol production of Saccharomyces cerevisiae without jeopardising its ability to cope with process stress during ethanol production. For this purpose, the mutant strains TEFmut7 and TEFmut2 with different GPD1 residual expression were studied in Very High Ethanol Performance (VHEP) fed-batch process under anaerobic conditions. Results Both strains showed a drastic reduction of the glycerol yield by 44 and 61% while the ethanol yield improved by 2 and 7% respectively. TEFmut2 strain showing the highest ethanol yield was accompanied by a 28% reduction of the biomass yield. The modulation of the glycerol formation led to profound redox and energetic changes resulting in a reduction of the ATP yield (YATP) and a modulation of the production of organic acids (acetate, pyruvate and succinate). Those metabolic rearrangements resulted in a loss of ethanol and stress tolerance of the mutants, contrarily to what was previously observed under aerobiosis. Conclusions This work demonstrates the potential of fine-tuned pathway engineering, particularly when a compromise has to be found between high product yield on one hand and acceptable growth, productivity and stress resistance on the other hand. Previous study showed that, contrarily to anaerobiosis, the resulting gain in ethanol yield was accompanied with no loss of ethanol tolerance under aerobiosis. Moreover those mutants were still able to produce up to 90 gl-1 ethanol in an anaerobic SSF process. Fine tuning metabolic strategy may then open encouraging possibilities for further

  8. Antimicrobial effects of weak acids on the survival of Escherichia coli O157:H7 under anaerobic conditions.

    PubMed

    Lu, Huiying J; Breidt, Frederick; Pérez-Díaz, Ilenys M; Osborne, Jason A

    2011-06-01

    Outbreaks of disease due to vegetative bacterial pathogens associated with acid foods (such as apple cider) have raised concerns about acidified vegetables and related products that have a similar pH (3.2 to 4.0). Escherichia coli O157:H7 and related strains of enterohemorrhagic E. coli (EHEC) have been identified as the most acid resistant vegetative pathogens in these products. Previous research has shown that the lack of dissolved oxygen in many hermetically sealed acid or acidified food products can enhance survival of EHEC compared with their survival under aerobic conditions. We compared the antimicrobial effects of several food acids (acetic, malic, lactic, fumaric, benzoic, and sorbic acids and sulfite) on a cocktail of EHEC strains under conditions representative of non-heat-processed acidified vegetables in hermetically sealed jars, holding the pH (3.2) and ionic strength (0.342) constant under anaerobic conditions. The overall antimicrobial effectiveness of weak acids used in this study was ranked, from most effective to least effective: sulfite > benzoic acid > sorbic acid > fumaric acid > L- and D-lactic acid > acetic acid > malic acid. These rankings were based on the estimated protonated concentrations required to achieve a 5-log reduction in EHEC after 24 h of incubation at 30°C. This study provides information that can be used to formulate safer acid and acidified food products and provides insights about the mode of action of weak acids against EHEC.

  9. Electron Acceptors Induce Secretion of Enterotoxigenic Escherichia coli Heat-Labile Enterotoxin under Anaerobic Conditions through Promotion of GspD Assembly

    PubMed Central

    Lu, Xi; Fu, Enqing; Xie, Yonghong

    2016-01-01

    Heat-labile enterotoxin (LT), the major virulence factor of enterotoxigenic Escherichia coli (ETEC), can lead to severe diarrhea and promotes ETEC adherence to intestinal epithelial cells. Most previous in vitro studies focused on ETEC pathogenesis were conducted under aerobic conditions, which do not reflect the real situation of ETEC infection because the intestine is anoxic. In this study, the expression and secretion of LT under anaerobic or microaerobic conditions were determined; LT was not efficiently secreted into the supernatant under anaerobic or microaerobic conditions unless terminal electron acceptors (trimethylamine N-oxide dihydrate [TMAO] or nitrate) were available. Furthermore, we found that the restoration effects of TMAO and nitrate on LT secretion could be inhibited by amytal or ΔtorCAD and ΔnarG E. coli strains, indicating that LT secretion under anaerobic conditions was dependent on the integrity of the respiratory chain. At the same time, electron acceptors increase the ATP level of ETEC, but this increase was not the main reason for LT secretion. Subsequently, the relationship between the integrity of the respiratory chain and the function of the type II secretion system was determined. The GspD protein, the secretin of ETEC, was assembled under anaerobic conditions and was accompanied by LT secretion when TMAO or nitrate was added. Our data also demonstrated that TMAO and nitrate could not induce the GspD assembly and LT secretion in ΔtorCAD and ΔnarG strains, respectively. Moreover, GspD assembly under anaerobic conditions was assisted by the pilot protein YghG. PMID:27430271

  10. Determination of the in vivo NAD:NADH ratio in Saccharomyces cerevisiae under anaerobic conditions, using alcohol dehydrogenase as sensor reaction.

    PubMed

    Bekers, K M; Heijnen, J J; van Gulik, W M

    2015-08-01

    With the current quantitative metabolomics techniques, only whole-cell concentrations of NAD and NADH can be quantified. These measurements cannot provide information on the in vivo redox state of the cells, which is determined by the ratio of the free forms only. In this work we quantified free NAD:NADH ratios in yeast under anaerobic conditions, using alcohol dehydrogenase (ADH) and the lumped reaction of glyceraldehyde-3-phosphate dehydrogenase and 3-phosphoglycerate kinase as sensor reactions. We showed that, with an alternative accurate acetaldehyde determination method, based on rapid sampling, instantaneous derivatization with 2,4 diaminophenol hydrazine (DNPH) and quantification with HPLC, the ADH-catalysed oxidation of ethanol to acetaldehyde can be applied as a relatively fast and simple sensor reaction to quantify the free NAD:NADH ratio under anaerobic conditions. We evaluated the applicability of ADH as a sensor reaction in the yeast Saccharomyces cerevisiae, grown in anaerobic glucose-limited chemostats under steady-state and dynamic conditions. The results found in this study showed that the cytosolic redox status (NAD:NADH ratio) of yeast is at least one order of magnitude lower, and is thus much more reduced, under anaerobic conditions compared to aerobic glucose-limited steady-state conditions. The more reduced state of the cytosol under anaerobic conditions has major implications for (central) metabolism. Accurate determination of the free NAD:NADH ratio is therefore of importance for the unravelling of in vivo enzyme kinetics and to judge accurately the thermodynamic reversibility of each redox reaction.

  11. 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.

  12. Pathways of N removal and N2O emission from a one-stage autotrophic N removal process under anaerobic conditions

    PubMed Central

    Li, Kai; Fang, Fang; Wang, Han; Wang, Chao; Chen, Youpeng; Guo, Jinsong; Wang, Xixi; Jiang, Fuyang

    2017-01-01

    To investigate the pathways of nitrogen (N) removal and N2O emission in a one-stage autotrophic N removal process during the non-aeration phase, biofilm from an intermittent aeration sequencing batch biofilm reactor (SBBR) and organic carbon-free synthetic wastewater were applied to two groups of lab-scale batch experiments in anaerobic conditions using a 15N isotopic tracer and specific inhibitors, respectively. Then, the microbial composition of the biofilm was analysed using high-throughput sequencing. The results of the 15N isotopic experiments showed that anaerobic ammonium oxidation (Anammox) was the main pathway of N transformation under anaerobic conditions and was responsible for 83–92% of N2 production within 24 h. Furthermore, experiments using specific inhibitors revealed that when nitrite was the main N source under anaerobic conditions, N2O emissions from heterotrophic denitrification (HD) and ammonia-oxidizing bacteria (AOB) denitrification were 64% and 36%, respectively. Finally, analysing the microbial composition demonstrated that Proteobacteria, Planctomycetes, and Nitrospirae were the dominant microbes, corresponding to 21%, 13%, and 7% of the microbial community, respectively, and were probably responsible for HD, Anammox, and AOB denitrification, respectively. PMID:28205581

  13. Pathways of N removal and N2O emission from a one-stage autotrophic N removal process under anaerobic conditions

    NASA Astrophysics Data System (ADS)

    Li, Kai; Fang, Fang; Wang, Han; Wang, Chao; Chen, Youpeng; Guo, Jinsong; Wang, Xixi; Jiang, Fuyang

    2017-02-01

    To investigate the pathways of nitrogen (N) removal and N2O emission in a one-stage autotrophic N removal process during the non-aeration phase, biofilm from an intermittent aeration sequencing batch biofilm reactor (SBBR) and organic carbon-free synthetic wastewater were applied to two groups of lab-scale batch experiments in anaerobic conditions using a 15N isotopic tracer and specific inhibitors, respectively. Then, the microbial composition of the biofilm was analysed using high-throughput sequencing. The results of the 15N isotopic experiments showed that anaerobic ammonium oxidation (Anammox) was the main pathway of N transformation under anaerobic conditions and was responsible for 83-92% of N2 production within 24 h. Furthermore, experiments using specific inhibitors revealed that when nitrite was the main N source under anaerobic conditions, N2O emissions from heterotrophic denitrification (HD) and ammonia-oxidizing bacteria (AOB) denitrification were 64% and 36%, respectively. Finally, analysing the microbial composition demonstrated that Proteobacteria, Planctomycetes, and Nitrospirae were the dominant microbes, corresponding to 21%, 13%, and 7% of the microbial community, respectively, and were probably responsible for HD, Anammox, and AOB denitrification, respectively.

  14. Anaerobic submerged membrane bioreactor (AnSMBR) for municipal wastewater treatment under mesophilic and psychrophilic temperature conditions.

    PubMed

    Martinez-Sosa, David; Helmreich, Brigitte; Netter, Thomas; Paris, Stefania; Bischof, Franz; Horn, Harald

    2011-11-01

    A pilot scale anaerobic submerged membrane bioreactor (AnSMBR) with an external filtration unit for municipal wastewater treatment was operated for 100 days. Besides gas sparging, additional shear was created by circulating sludge to control membrane fouling. During the first 69 days, the reactor was operated under mesophilic temperature conditions. Afterwards, the temperature was gradually reduced to 20 °C. A slow and linear increase in the filtration resistance was observed under critical flux conditions (7 L/(m2 h)) at 35 °C. However, an increase in the fouling rate probably linked to an accumulation of solids, a higher viscosity and soluble COD concentrations in the reactor was observed at 20 °C. The COD removal efficiency was close to 90% under both temperature ranges. Effluent COD and BOD5 concentrations were lower than 80 and 25 mg/L, respectively. Pathogen indicator microorganisms (fecal coliforms bacteria) were reduced by log(10)5. Hence, the effluent could be used for irrigation purposes in agriculture. Copyright © 2011 Elsevier Ltd. All rights reserved.

  15. Corrosion and fate of depleted uranium penetrators under progressively anaerobic conditions in estuarine sediment.

    PubMed

    Handley-Sidhu, Stephanie; Worsfold, Paul J; Boothman, Christopher; Lloyd, Jonathan R; Alvarez, Rebeca; Livens, Francis R; Vaughan, David J; Keith-Roach, Miranda J

    2009-01-15

    The testing of armor-piercing depleted uranium (DU) "penetrators" has resulted in the deposition of DU in the sediments of the Solway Firth, UK. In this study, DU-amended, microcosm experiments simulating Solway Firth sediments under high (31.5) and medium (16.5) salinity conditions were used to investigate the effect of salinity and biogeochemical conditions on the corrosion and fate of DU, and the impact of the corroding DU on the microbial population. Under suboxic conditions, the average corrosion rates were the same forthe 31.5 and 16.5 salinity systems at 0.056 +/- 0.006 g cm(-2) y(-1), implying that complete corrosion of a 120 mm penetrator would take approximately 540 years. Under sulfate-reducing conditions, corrosion ceased due to passivation of the surface. Corroding DU resulted in more reducing conditions and decreased microbial diversity as indicated by DNA sequencing and phylogenetic analysis. The lack of colloidal and particulate DU corrosion products, along with measurable dissolved U and a homogeneous association of U with the sediment, suggest that U was transported from the penetrator surface into the surrounding environment through dissolution of U(VI), with subsequent interactions resulting in the formation of secondary uranium species in the sediment.

  16. Co-effects of pyrene and nitrate on the activity and abundance of soil denitrifiers under anaerobic condition.

    PubMed

    Zhou, Zhi-Feng; Yao, Yan-Hong; Wang, Ming-Xia; Zuo, Xiao-Hu

    2017-04-18

    It has previously been confirmed that polycyclic aromatic hydrocarbons (PAHs) could be degraded by soil microbes coupling with denitrification, but the relationships among soil denitrifiers, PAHs, and nitrate under obligate anaerobic condition are still unclear. Here, co-effects of pyrene and nitrate on the activity and abundance of soil denitrifiers were investigated through a 45-day incubation experiment. Two groups of soil treatments with (N30) and without (N0) nitrate (30 mg kg(-1) dry soil) amendment were conducted, and each group contained three treatments with different pyrene concentrations (0, 30, and 60 mg kg(-1) dry soil denoted as P0, P30, and P60, respectively). The pyrene content, abundances of denitrification concerning genes (narG, periplasmic nitrate reductase gene; nirS, cd 1-nitrite reductase gene; nirK, copper-containing nitrite reductase gene), and productions of N2O and CO2 were measured at day 3, 14, 28, and 45, and the bacterial community structures in four represented treatments (N0P0, N0P60, N30P0, and N30P60) were analyzed at day 45. The results indicated that the treatments with higher pyrene concentration had higher final pyrene removal rates than the treatments with lower pyrene concentration. Additionally, intensive emission of N2O was detected in all treatments only at day 3, but a continuous production of CO2 was measured in each treatment during the incubation. Nitrate amendment could enhance the activity of soil denitrifiers, and be helpful for soil microbes to sustain their activity. While pyrene seemed had no influence on the productions of N2O and CO2, and amendment with pyrene or nitrate both had no obvious effect on abundances of denitrification concerning genes. Furthermore, it was nitrate but not pyrene had an obvious influence on the community structure of soil bacteria. These results revealed that, under anaerobic condition, the activity and abundance of soil denitrifiers both were insensitive to pyrene, but nitrate

  17. Anaerobic Biodegradation of soybean biodiesel and diesel blends under sulfate-reducing conditions

    EPA Science Inventory

    Biotransformation of soybean biodiesel and its biodiesel/petrodiesel blends were investigated under sulfate-reducing conditions. Three blends of biodiesel, B100, B50, and B0, were treated using microbial cultures pre-acclimated to B100 (biodiesel only) and B80 (80% biodiesel and ...

  18. Anaerobic biodegradation of soybean biodiesel and diesel blends under sulfate-reducing conditions.

    PubMed

    Wu, Shuyun; Yassine, Mohamad H; Suidan, Makram T; Venosa, Albert D

    2016-10-01

    Biotransformation of soybean biodiesel and its biodiesel/petrodiesel blends were investigated under sulfate-reducing conditions. Three blends of biodiesel, B100, B50, and B0, were treated using microbial cultures pre-acclimated to B100 (biodiesel only) and B80 (80% biodiesel and 20% petrodiesel). Results indicate that the biodiesel could be effectively biodegraded in the presence or absence of petrodiesel, whereas petrodiesel could not be biodegraded at all under sulfate-reducing conditions. The kinetics of biodegradation of individual Fatty Acid Methyl Ester (FAME) compounds and their accompanying sulfate-reduction rates were studied using a serum bottle test. As for the biodegradation of individual FAME compounds, the biodegradation rates for the saturated FAMEs decreased with increasing carbon chain length. For unsaturated FAMEs, biodegradation rates increased with increasing number of double bonds. The presence of petrodiesel had a greater effect on the rate of biodegradation of biodiesel than on the extent of removal.

  19. A genomic island of the sulfate-reducing bacterium Desulfovibrio vulgaris Hildenborough promotes survival under stress conditions while decreasing the efficiency of anaerobic growth.

    PubMed

    Johnston, Shawna; Lin, Shiping; Lee, Phoebe; Caffrey, Sean M; Wildschut, Janine; Voordouw, Johanna K; da Silva, Sofia M; Pereira, Ines A C; Voordouw, Gerrit

    2009-04-01

    A 47 kb genomic island (GEI) bracketed by 50 bp direct repeats, containing 52 annotated genes, was found to delete spontaneously from the genome of Desulfovibrio vulgaris Hildenborough. The island contains genes for site-specific recombinases and transposases, rubredoxin:oxygen oxidoreductase-1 (Roo1) and hybrid cluster protein-1 (Hcp1), which promote survival in air and nitrite stress. The numbering distinguishes these from the Roo2 and Hcp2 homologues for which the genes are located elsewhere in the genome. Cells with and without the island (GEI(+) and GEI(-) cells respectively) were obtained by colony purification. GEI(-) cells arise in anaerobic cultures of colony-purified GEI(+) cells, indicating that the site-specific recombinases encoded by the island actively delete this region. GEI(+) cells survive better in microaerophilic conditions due to the presence of Roo1, whereas the Hcps appear to prevent inhibition by sulfur and polysulfide, which are formed by chemical reaction of sulfide and nitrite. Hence, the island confers resistance to oxygen and nitrite stress. However, GEI(-) cells have a higher growth rate in anaerobic media. Microarrays and enzyme activity stains indicated that the GEI(-) cells have increased expression of genes, which promote anaerobic energy conservation, explaining the higher growth rate. Hence, while lowering the efficiency of anaerobic metabolism, the GEI increases the fitness of D. vulgaris under stress conditions, a feature reminiscent of pathogenicity islands which allow more effective colonization of environments provided by the targeted hosts.

  20. Effects of anaerobic growth conditions on biomass accumulation, root morphology, and efficiencies of nutrient uptake and utilization in seedlings of some southern coastal plain

    SciTech Connect

    Topa, M.A.

    1984-01-01

    Seedlings of pond, and loblolly pines were grown in a non-circulating, continuously-flowing solution culture under anaerobic (0.75 mg/1 O/sub 2/) conditions to determine the effects of anaerobiosis on overall growth, root morphology and efficiencies of nutrient uptake and utilization. Although shoot growth of the 11-week old loblolly and pond was not affected by anaerobic treatment, it did significantly reduce root biomass. Sand pine suffered the largest biomass reduction. Flooding tolerance was positively correlated with morphological changes which enhanced root internal aeration. Oxygen transport from shoot to the root was demonstrated via rhizosphere oxidation experiments using indigo-carmine dye solutions and polarography. Stem and root collar lenticels were found to be the major sites of atmospheric O/sub 2/ entry for submerged roots. Longitudinal and radial pathways for gas diffusion via intercellular spaces in the pericycle and ray parenchyma, respectively, were elucidated histologically. Lenticel and aerenchyma development, and rhizosphere oxidation in roots of anaerobically-grown sand pine seedlings were minimal. Elemental analyses showed that anaerobic conditions interfered with nutrient absorption and utilization. Short-term /sup 32/P uptake experiments with intact seedlings indicated that net absorption decreased because of the reduction in root biomass. Phosphorus absorption rates were negatively correlated with internal tissue phosphorus concentrations, and root and shoot biomass. 315 refs., 25 figs., 14 tabs.

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

    PubMed

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

    2004-06-01

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

  2. Anaerobic co-digestion of food waste and chemically enhanced primary-treated sludge under mesophilic and thermophilic conditions.

    PubMed

    Obulisamy, Parthiba Karthikeyan; Chakraborty, Debkumar; Selvam, Ammaiyappan; Wong, Jonathan W C

    2016-12-01

    Anaerobic co-digestion of food waste with primary sewage sludge is beneficial for urban centers, while the optimized conditions reported in the literature are not locally suitable for Hong Kong. Therefore, the present study was aimed to develop an optimized mixing ratio of food waste to chemically enhanced primary-treated sewer sludge (CEPT) for co-digestion using batch tests under mesophilic (37°C) and thermophilic (55°C) conditions. The mixing ratios of 1:1, 1:2, 1:3, 2:1 and 3:1 (v v(-1)) of food waste to CEPT sludge was tested under the following conditions: temperature - 35°C and 55°C; pH - not regulated; agitation - 150 rpm and time - 20 days. The thermophilic incubations led a good hydrolysis rate and 2-12-fold higher enzyme activities than in mesophilic incubations for different mixing ratios. While the acidogenesis were found retarded that leading to 'sour and stuck' digestion for all mixing ratio of food waste to CEPT sludge from thermophilic incubations. The measured zeta potential was most favourable (-5 to -16.8 mV) for methane production under thermophilic incubations; however the CH4 recovery was less than that in mesophilic incubations. The results suggested that the quick hydrolysis and subsequent acid accumulation under thermophilic incubation lead to inhibited methanogenesis at the early stage than in mesophilic systems. It is concluded that buffer addition is therefore required for any mixing ratio of food waste to CEPT sludge for improved CH4 recovery for both mesophilic and thermophilic operations.

  3. Unravelling the active microbial community in a thermophilic anaerobic digester-microbial electrolysis cell coupled system under different conditions.

    PubMed

    Cerrillo, Míriam; Viñas, Marc; Bonmatí, August

    2017-03-01

    Thermophilic anaerobic digestion (AD) of pig slurry coupled to a microbial electrolysis cell (MEC) with a recirculation loop was studied at lab-scale as a strategy to increase AD stability when submitted to organic and nitrogen overloads. The system performance was studied, with the recirculation loop both connected and disconnected, in terms of AD methane production, chemical oxygen demand removal (COD) and volatile fatty acid (VFA) concentrations. Furthermore, the microbial population was quantitatively and qualitatively assessed through DNA and RNA-based qPCR and high throughput sequencing (MiSeq), respectively to identify the RNA-based active microbial populations from the total DNA-based microbial community composition both in the AD and MEC reactors under different operational conditions. Suppression of the recirculation loop reduced the AD COD removal efficiency (from 40% to 22%) and the methane production (from 0.32 to 0.03 m(3) m(-3) d(-1)). Restoring the recirculation loop led to a methane production of 0.55 m(3) m(-3) d(-1) concomitant with maximum MEC COD and ammonium removal efficiencies of 29% and 34%, respectively. Regarding microbial analysis, the composition of the AD and MEC anode populations differed from really active microorganisms. Desulfuromonadaceae was revealed as the most active family in the MEC (18%-19% of the RNA relative abundance), while hydrogenotrophic methanogens (Methanobacteriaceae) dominated the AD biomass. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Reactor performance and microbial community dynamics during solid-state anaerobic digestion of corn stover at mesophilic and thermophilic conditions.

    PubMed

    Shi, Jian; Wang, Zhongjiang; Stiverson, Jill A; Yu, Zhongtang; Li, Yebo

    2013-05-01

    Reactor performance and microbial community dynamics were investigated during solid state anaerobic digestion (SS-AD) of corn stover at mesophilic and thermophilic conditions. Thermophilic SS-AD led to faster and greater reductions of cellulose and hemicelluloses during the first 12 days compared to mesophilic SS-AD. However, accumulation of volatile fatty acids (VFAs) was 5-fold higher at thermophilic than mesophilic temperatures, resulting in a large pH drop during days 6-12 in the thermophilic reactors. Culture-based enumeration revealed 10-50 times greater populations of cellulolytic and xylanolytic microbes during thermophilic SS-AD than mesophilic SS-AD. DGGE analysis of PCR amplified 16S rRNA genes showed dynamic shifts, especially during the thermophilic SS-AD, of bacterial and archaeal communities over the 38 days of SS-AD as a result of acclimation of the initial seed microbial consortia to the lignocellulosic feedstock. The findings of this study can guide future studies to improve efficiency and stability of SS-AD. Copyright © 2013 Elsevier Ltd. All rights reserved.

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

    PubMed

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

    2014-08-01

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

  6. Anaerobic digestion of whole stillage from dry-grind corn ethanol plant under mesophilic and thermophilic conditions.

    PubMed

    Eskicioglu, Cigdem; Kennedy, Kevin J; Marin, Juan; Strehler, Benjamin

    2011-01-01

    Anaerobic digestion of whole stillage from a dry-grind corn-based ethanol plant was evaluated by batch and continuous-flow digesters under thermophilic and mesophilic conditions. At whole corn stillage concentrations of 6348 to 50,786 mg total chemical oxygen demand (TCOD)/L, at standard temperature (0 °C) and pressure (1 atm), preliminary biochemical methane potential assays produced 88±8 L (49±5 L CH4) and 96±19 L (65±14 L CH4) biogas per L stillage from mesophilic and thermophilic digesters, respectively. Continuous-flow studies for the full-strength stillage (TCOD=254 g/L) at organic loadings of 4.25, 6.30 and 9.05 g TCOD/L days indicated unstable performance for the thermophilic digester. Among the sludge retention times (SRTs) of 60, 45 and 30 days tested, the mesophilic digestion was successful only at 60 days-SRT which does not represent a practical operation time for a large scale bioethanol plant. Future laboratory studies will focus on different reactor configurations to reduce the SRT needed in the digesters.

  7. Decolorization and detoxification of a sulfonated triphenylmethane dye aniline blue by Shewanella oneidensis MR-1 under anaerobic conditions.

    PubMed

    Wu, Yongmin; Xiao, Xiang; Xu, Cancan; Cao, Danming; Du, Daolin

    2013-08-01

    In this work, the extracellular decolorization of aniline blue, a sulfonated triphenylmethane dye, by Shewanella oneidensis MR-1 was confirmed. S. oneidensis MR-1 showed a high capacity for decolorizing aniline blue even at a concentration of up to 1,000 mg/l under anaerobic conditions. Maximum decolorization efficiency appeared at pH 7.0 and 30 °C. Lactate was a better candidate of electron donor for the decolorization of aniline blue. The addition of nitrate, hydrous ferric oxide, or trimethylamine N-oxide all could cause a significant decline of decolorization efficiency. The Mtr respiratory pathway was found to be involved into the decolorization of aniline blue by S. oneidensis MR-1. The toxicity evaluation through phytotoxicity and genotoxicity showed that S. oneidensis MR-1 could decrease the toxicity of aniline blue during the decolorization process. Thus, this work may facilitate a better understanding on the degradation mechanisms of the triphenylmethane dyes by Shewanella and is beneficial to their application in bioremediation.

  8. Ammonia inhibition on hydrogen enriched anaerobic digestion of manure under mesophilic and thermophilic conditions.

    PubMed

    Wang, Han; Zhang, Yifeng; Angelidaki, Irini

    2016-11-15

    Capturing of carbon dioxide by hydrogen derived from excess renewable energy (e.g., wind mills) to methane in a microbially catalyzed process offers an attractive technology for biogas production and upgrading. This bioconversion process is catalyzed by hydrogenotrophic methanogens, which are known to be sensitive to ammonia. In this study, the tolerance of the biogas process under supply of hydrogen, to ammonia toxicity was studied under mesophilic and thermophilic conditions. When the initial hydrogen partial pressure was 0.5 atm, the methane yield at high ammonia load (7 g NH4(+)-N L(-1)) was 41.0% and 22.3% lower than that at low ammonia load (1 g NH4(+)-N L(-1)) in mesophilic and thermophilic condition, respectively. Meanwhile no significant effect on the biogas composition was observed. Moreover, we found that hydrogentrophic methanogens were more tolerant to the ammonia toxicity than acetoclastic methanogens in the hydrogen enriched biogas production and upgrading processes. The highest methane production yield was achieved under 0.5 atm hydrogen partial pressure in batch reactors at all the tested ammonia levels. Furthermore, the thermophilic methanogens at 0.5 atm of hydrogen partial pressure were more tolerant to high ammonia levels (≥5 g NH4(+)-N L(-1)), compared with mesophilic methanogens. The present study offers insight in developing resistant hydrogen enriched biogas production and upgrading processes treating ammonia-rich waste streams.

  9. Linked Redox Precipitation of Sulfur and Selenium under Anaerobic Conditions by Sulfate-Reducing Bacterial Biofilms

    PubMed Central

    Hockin, Simon L.; Gadd, Geoffrey M.

    2003-01-01

    A biofilm-forming strain of sulfate-reducing bacteria (SRB), isolated from a naturally occurring mixed biofilm and identified by 16S rDNA analysis as a strain of Desulfomicrobium norvegicum, rapidly removed 200 μM selenite from solution during growth on lactate and sulfate. Elemental selenium and elemental sulfur were precipitated outside SRB cells. Precipitation occurred by an abiotic reaction with bacterially generated sulfide. This appears to be a generalized ability among SRB, arising from dissimilatory sulfide biogenesis, and can take place under low redox conditions and in the dark. The reaction represents a new means for the deposition of elemental sulfur by SRB under such conditions. A combination of transmission electron microscopy, environmental scanning electron microscopy, and cryostage field emission scanning electron microscopy were used to reveal the hydrated nature of SRB biofilms and to investigate the location of deposited sulfur-selenium in relation to biofilm elements. When pregrown SRB biofilms were exposed to a selenite-containing medium, nanometer-sized selenium-sulfur granules were precipitated within the biofilm matrix. Selenite was therefore shown to pass through the biofilm matrix before reacting with bacterially generated sulfide. This constitutes an efficient method for the removal of toxic concentrations of selenite from solution. Implications for environmental cycling and the fate of sulfur and selenium are discussed, and a general model for the potential action of SRB in selenium transformations is presented. PMID:14660350

  10. Linked redox precipitation of sulfur and selenium under anaerobic conditions by sulfate-reducing bacterial biofilms.

    PubMed

    Hockin, Simon L; Gadd, Geoffrey M

    2003-12-01

    A biofilm-forming strain of sulfate-reducing bacteria (SRB), isolated from a naturally occurring mixed biofilm and identified by 16S rDNA analysis as a strain of Desulfomicrobium norvegicum, rapidly removed 200 micro M selenite from solution during growth on lactate and sulfate. Elemental selenium and elemental sulfur were precipitated outside SRB cells. Precipitation occurred by an abiotic reaction with bacterially generated sulfide. This appears to be a generalized ability among SRB, arising from dissimilatory sulfide biogenesis, and can take place under low redox conditions and in the dark. The reaction represents a new means for the deposition of elemental sulfur by SRB under such conditions. A combination of transmission electron microscopy, environmental scanning electron microscopy, and cryostage field emission scanning electron microscopy were used to reveal the hydrated nature of SRB biofilms and to investigate the location of deposited sulfur-selenium in relation to biofilm elements. When pregrown SRB biofilms were exposed to a selenite-containing medium, nanometer-sized selenium-sulfur granules were precipitated within the biofilm matrix. Selenite was therefore shown to pass through the biofilm matrix before reacting with bacterially generated sulfide. This constitutes an efficient method for the removal of toxic concentrations of selenite from solution. Implications for environmental cycling and the fate of sulfur and selenium are discussed, and a general model for the potential action of SRB in selenium transformations is presented.

  11. Effect of fermentation conditions on biohydrogen production from cassava starch by anaerobic mixed cultures

    NASA Astrophysics Data System (ADS)

    Tien, Hai M.; Le, Kien A.; Tran, An T.; Le, Phung K.

    2016-06-01

    In this work, a series of batch tests were conducted to investigate the effect of pH, temperature, fermentation time, and inoculums ratio to hydrogen production using cassava starch as a substrate. The statistical analysis of the experiment indicated that the significant effects for the fermentation yield were the main effect of temperature, pH and inoculums ratio. It was fouund that the suitable fermentation conditions of biohydrogen production should be at temperature 40 ° C; pH 6.5, inoculums to medium ratio 10 % and COD operation at 4800 g/mL. The maximum value of hydrogen volume produced was 76.22 mL. These affected has been evaluated and the result can be used as an reference for the pilot or industrial biohydrogen production.

  12. Post-translational modification of Cu/Zn superoxide dismutase under anaerobic conditions.

    PubMed

    Leitch, Jeffry M; Li, Cissy X; Baron, J Allen; Matthews, Lauren M; Cao, Xiaohang; Hart, P John; Culotta, Valeria C

    2012-01-17

    In eukaryotic organisms, the largely cytosolic copper- and zinc-containing superoxide dismutase (Cu/Zn SOD) enzyme represents a key defense against reactive oxygen toxicity. Although much is known about the biology of this enzyme under aerobic conditions, less is understood regarding the effects of low oxygen levels on Cu/Zn SOD enzymes from diverse organisms. We show here that like bakers' yeast (Saccharomyces cerevisiae), adaptation of the multicellular Caenorhabditis elegans to growth at low oxygen levels involves strong downregulation of its Cu/Zn SOD. Much of this regulation occurs at the post-translational level where CCS-independent activation of Cu/Zn SOD is inhibited. Hypoxia inactivates the endogenous Cu/Zn SOD of C. elegans Cu/Zn SOD as well as a P144 mutant of S. cerevisiae Cu/Zn SOD (herein denoted Sod1p) that is independent of CCS. In our studies of S. cerevisiae Sod1p, we noted a post-translational modification to the inactive enzyme during hypoxia. Analysis of this modification by mass spectrometry revealed phosphorylation at serine 38. Serine 38 represents a putative proline-directed kinase target site located on a solvent-exposed loop that is positioned at one end of the Sod1p β-barrel, a region immediately adjacent to residues previously shown to influence CCS-dependent activation. Although phosphorylation of serine 38 is minimal when the Sod1p is abundantly active (e.g., high oxygen level), up to 50% of Sod1p can be phosphorylated when CCS activation of the enzyme is blocked, e.g., by hypoxia or low-copper conditions. Serine 38 phosphorylation can be a marker for inactive pools of Sod1p.

  13. Effect of increasing total solids contents on anaerobic digestion of food waste under mesophilic conditions: performance and microbial characteristics analysis.

    PubMed

    Yi, Jing; Dong, Bin; Jin, Jingwei; Dai, Xiaohu

    2014-01-01

    The total solids content of feedstocks affects the performances of anaerobic digestion and the change of total solids content will lead the change of microbial morphology in systems. In order to increase the efficiency of anaerobic digestion, it is necessary to understand the role of the total solids content on the behavior of the microbial communities involved in anaerobic digestion of organic matter from wet to dry technology. The performances of mesophilic anaerobic digestion of food waste with different total solids contents from 5% to 20% were compared and the microbial communities in reactors were investigated using 454 pyrosequencing technology. Three stable anaerobic digestion processes were achieved for food waste biodegradation and methane generation. Better performances mainly including volatile solids reduction and methane yield were obtained in the reactors with higher total solids content. Pyrosequencing results revealed significant shifts in bacterial community with increasing total solids contents. The proportion of phylum Chloroflexi decreased obviously with increasing total solids contents while other functional bacteria showed increasing trend. Methanosarcina absolutely dominated in archaeal communities in three reactors and the relative abundance of this group showed increasing trend with increasing total solids contents. These results revealed the effects of the total solids content on the performance parameters and the behavior of the microbial communities involved in the anaerobic digestion of food waste from wet to dry technologies.

  14. Effect of Increasing Total Solids Contents on Anaerobic Digestion of Food Waste under Mesophilic Conditions: Performance and Microbial Characteristics Analysis

    PubMed Central

    Jin, Jingwei; Dai, Xiaohu

    2014-01-01

    The total solids content of feedstocks affects the performances of anaerobic digestion and the change of total solids content will lead the change of microbial morphology in systems. In order to increase the efficiency of anaerobic digestion, it is necessary to understand the role of the total solids content on the behavior of the microbial communities involved in anaerobic digestion of organic matter from wet to dry technology. The performances of mesophilic anaerobic digestion of food waste with different total solids contents from 5% to 20% were compared and the microbial communities in reactors were investigated using 454 pyrosequencing technology. Three stable anaerobic digestion processes were achieved for food waste biodegradation and methane generation. Better performances mainly including volatile solids reduction and methane yield were obtained in the reactors with higher total solids content. Pyrosequencing results revealed significant shifts in bacterial community with increasing total solids contents. The proportion of phylum Chloroflexi decreased obviously with increasing total solids contents while other functional bacteria showed increasing trend. Methanosarcina absolutely dominated in archaeal communities in three reactors and the relative abundance of this group showed increasing trend with increasing total solids contents. These results revealed the effects of the total solids content on the performance parameters and the behavior of the microbial communities involved in the anaerobic digestion of food waste from wet to dry technologies. PMID:25051352

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

    PubMed Central

    Regnell, Olof; Tunlid, Anders

    1991-01-01

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

  16. 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 ...

  17. Anaerobic biodegradation of polylactic acid under mesophilic condition using thermal-alkaline pretreatment

    NASA Astrophysics Data System (ADS)

    Samitthiwetcharong, Sutisa; Kullavanijaya, Pratin; Chavalparit, Orathai

    2017-07-01

    The propose of this study was to investigate the effect of thermal-alkaline pretreatment with emphasis on sodium hydroxide concentration (NaOH), temperature and reaction time, on enhancement of polylactic acid (PLA) films degradation and biogas production. The results found that NaOH concentration and reaction time were two main parameters influencing on PLA degradation. While, less significant was found for temperature. From the Response Surface Methodology (RSM), it was concluded that the optimum pretreatment conditions were at 0.5 M of NaOH, temperature of 60°C and 24 hr of reaction time. This was generated about 3.7 times (215.47 ml/gVSadded) higher gas production comparing to non-pretreated PLA films which was 58.28 ml/gVSadded. The maximum biodegradability of PLA film was 20.14%. This was estimated to be 4.7 times higher than non-pretreated PLA (4.32%). This finding demonstrated the benefit of thermal-alkaline pretreatment on surface of PLA films destruction. Consequently, the microbial enzymes could degrade PLA more easily, resulting in an increase of biogas production.

  18. Influence of Environmental Conditions on Methanogenic Compositions in Anaerobic Biogas Reactors

    PubMed Central

    Karakashev, Dimitar; Batstone, Damien J.; Angelidaki, Irini

    2005-01-01

    The influence of environmental parameters on the diversity of methanogenic communities in 15 full-scale biogas plants operating under different conditions with either manure or sludge as feedstock was studied. Fluorescence in situ hybridization was used to identify dominant methanogenic members of the Archaea in the reactor samples; enriched and pure cultures were used to support the in situ identification. Dominance could be identified by a positive response by more than 90% of the total members of the Archaea to a specific group- or order-level probe. There was a clear dichotomy between the manure digesters and the sludge digesters. The manure digesters contained high levels of ammonia and of volatile fatty acids (VFA) and were dominated by members of the Methanosarcinaceae, while the sludge digesters contained low levels of ammonia and of VFA and were dominated by members of the Methanosaetaceae. The methanogenic diversity was greater in reactors operating under mesophilic temperatures. The impact of the original inoculum used for the reactor start-up was also investigated by assessment of the present population in the reactor. The inoculum population appeared to have no influence on the eventual population. PMID:15640206

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

    NASA Astrophysics Data System (ADS)

    Gorbacheva, M.

    2012-04-01

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

  20. Effects of temperature on anaerobic decomposition of high-molecular weight organic matter under sulfate-reducing conditions

    NASA Astrophysics Data System (ADS)

    Matsui, Takato; Kojima, Hisaya; Fukui, Manabu

    2013-03-01

    Most sedimentary mineralization occurs along coasts under anaerobic conditions. In the absence of oxygen, high-molecular weight organic matter in marine sediments is gradually decomposed by hydrolysis, fermentation and sulfate reduction. Because of the different responses of the respective steps to temperature, degradation may be specifically slowed or stopped in certain step. To evaluate the effect of temperature on cellobiose degradation, culture experiments were performed at six different temperatures (3 °C, 8 °C, 13 °C, 18 °C, 23 °C, and 28 °C) under sulfate-reducing conditions. This study measured the concentrations of sulfide, dissolved organic carbon (DOC), and organic acids during that degradation. Degradation patterns were divided into three temperature groups: 3 °C, 8/13 °C, and 18/23/28 °C. The decrease in DOC proceeded in two steps, except at 3 °C. The length of the stagnant phase separating these two steps differed greatly between temperatures of 8/13 °C and 18/23/28 °C. In the first step, organic carbon was consumed by hydrolysis, fermentation and sulfate reduction. In the second step, acetate accumulated during the first step was oxidized by sulfate reduction. Bacterial communities in the cultures were analyzed by denaturing gradient gel electrophoresis (DGGE); the major differences among the three temperature groups were attributed to shifts in acetate-using sulfate reducers of the genus Desulfobacter. This suggests that temperature characteristics of dominant acetate oxidizers are important factors in determining the response of carbon flow in coastal marine sediments in relation to the changes in temperature.

  1. [Influence of extracellular polymeric substance on enzyme hydrolysis of sludge under anaerobic condition].

    PubMed

    Chen, Wei; Jia, Yuan-Yuan; Zheng, Wei; Li, Xiao-Ming; Zhou, Jun; Yang, Qi; Luo, Kun

    2011-08-01

    The effect of extracellular polymeric substance (EPS) on the enzymatic solubilisation of sludge and the changes of chemical components was investigated. Sludge solubilization with and without EPS was studied in the enzymatic system, and in the normal system without enzyme addition, respectively. The result indicated that only EPS could be hydrolyzed when the enzyme addition less than 20 mg/g, while the cell lysis occurred significantly with the doses of enzymes increasing. Treatment with lysozyme for the original sludge was proved to have a higher hydrolysis efficiency, and the SCOD/TCOD rate reached up to 28.14%. And at the enzyme dosage of 60 mg/g, the VSS removal rate increased to 51.66% and the concentration of DNA attained 68.34 mg/g (calculated by VSS) after 48 h reaction, which were 29.01% and 59.63 mg/g higher than the control test, respectively, and were 24.86% and 53.39 mg/g higher than that with EPS removed in advance, respectively. Meanwhile, NH4+ -N, PO4(3-)-P and SCOD showed high dissolution efficiency, and the maximal concentrations achieved to 503 mg/L, 78.9 mg/L and 3171 mg/L, respectively. After removal of extracellular polymers, higher lysis efficiency was also observed by protease and cellulose, by which VSS reduction rate reached to 49.95% and 39.85%, respectively. The concentration of DNA showed a correlation coefficient of more than 0.9 with the concentrations of SCOD, NH4+ -N and PO4(3-)-P. And the highest hydrolysis rate obtained in 6 hours, which was about 3 hours earlier than the control test. Moreover, under those condition, sludge hydrolyzation could be well realized by only small amount of the enzyme addition.

  2. Dissolution Coupled Biodegradation of Pce by Inducing In-Situ Biosurfactant Production Under Anaerobic Conditions

    NASA Astrophysics Data System (ADS)

    Dominic, J.; Nambi, I. M.

    2013-12-01

    Biosurfactants have proven to enhance the bioavailability and thereby elevate the rate of degradation of Light Non Aqueous Phase Liquids (LNAPLs) such as crude oil and petroleum derivatives. In spite of their superior characteristics, use of these biomolecules for remediation of Dense Non Aqueous Phase Liquids (DNAPLs) such as chlorinated solvents is still not clearly understood. In this present study, we have investigated the fate of tetrachloroethylene (PCE) by inducing in-situ biosurfactants production, a sustainable option which hypothesizes increase in bioavailability of LNAPLs. In order to understand the effect of biosurfactants on dissolution and biodegradation under the inducement of in-situ biosurfactant production, batch experiments were conducted in pure liquid media. The individual influence of each process such as biosurfactant production, dissolution of PCE and biodegradation of PCE were studied separately for getting insights on the synergistic effect of each process on the fate of PCE. Finally the dissolution coupled biodegradation of non aqueous phase PCE was studied in conditions where biosurfactant production was induced by nitrate limitation. The effect of biosurfactants was differentiated by repeating the same experiments were the biosurfactant production was retarded. The overall effect of in-situ biosurfactant production process was evaluated by use of a mathematical model. The process of microbial growth, biosurfactant production, dissolution and biodegradation of PCE were translated as ordinary differential equations. The modelling exercise was mainly performed to get insight on the combined effects of various processes that determine the concentration of PCE in its aqueous and non-aqueous phases. Model simulated profiles of PCE with the kinetic coefficients evaluated earlier from individual experiments were compared with parameters fitted for observations in experiments with dissolution coupled biodegradation process using optimization

  3. Kinetics of Fe(II)-catalyzed transformation of 6-line ferrihydrite under anaerobic flow conditions

    SciTech Connect

    Yang, L.; Steefel, C.I.; Marcus, M.A.; Bargar, J.R.

    2010-04-01

    The readsorption of ferrous ions produced by the abiotic and microbially-mediated reductive dissolution of iron oxy-hydroxides drives a series of transformations of the host minerals. To further understand the mechanisms by which these transformations occur and their kinetics within a microporous flow environment, flow-through experiments were conducted in which capillary tubes packed with ferrihydrite-coated glass spheres were injected with inorganic Fe(II) solutions under circumneutral pH conditions at 25 C. Synchrotron X-ray diffraction was used to identify the secondary phase(s) formed and to provide data for quantitative kinetic analysis. At concentrations at and above 1.8 mM Fe(II) in the injection solution, magnetite was the only secondary phase formed (no intermediates were detected), with complete transformation following a nonlinear rate law requiring 28 hours and 150 hours of reaction at 18 and 1.8 mM Fe(II), respectively. However, when the injection solution consisted of 0.36 mM Fe(II), goethite was the predominant reaction product and formed much more slowly according to a linear rate law, while only minor magnetite was formed. When the rates are normalized based on the time to react half of the ferrihydrite on a reduced time plot, it is apparent that the 1.8 mM and 18 mM input Fe(II) experiments can be described by the same reaction mechanism, while the 0.36 input Fe(II) experiment is distinct. The analysis of the transformation kinetics suggest that the transformations involved an electron transfer reaction between the aqueous as well as sorbed Fe(II) and ferrihydrite acting as a semiconductor, rather than a simple dissolution and recrystallization mechanism. A transformation mechanism involving sorbed inner sphere Fe(II) alone is not supported, since the essentially equal coverage of sorption sites in the 18 mM and 1.8 mM Fe(II) injections cannot explain the difference in the transformation rates observed.

  4. Contribution of quinone-reducing microorganisms to the anaerobic biodegradation of organic compounds under different redox conditions.

    PubMed

    Cervantes, Francisco J; Gutiérrez, Claudia H; López, Kitzia Y; Estrada-Alvarado, María Isabel; Meza-Escalante, Edna R; Texier, Anne-Claire; Cuervo, Flor; Gómez, Jorge

    2008-04-01

    The capacity of two anaerobic consortia to oxidize different organic compounds, including acetate, propionate, lactate, phenol and p-cresol, in the presence of nitrate, sulfate and the humic model compound, anthraquinone-2,6-disulfonate (AQDS) as terminal electron acceptors, was evaluated. Denitrification showed the highest respiratory rates in both consortia studied and occurred exclusively during the first hours of incubation for most organic substrates degraded. Reduction of AQDS and sulfate generally started after complete denitrification, or even occurred at the same time during the biodegradation of p-cresol, in anaerobic sludge incubations; whereas methanogenesis did not significantly occur during the reduction of nitrate, sulfate, and AQDS. AQDS reduction was the preferred respiratory pathway over sulfate reduction and methanogenesis during the anaerobic oxidation of most organic substrates by the anaerobic sludge studied. In contrast, sulfate reduction out-competed AQDS reduction during incubations performed with anaerobic wetland sediment, which did not achieve any methanogenic activity. Propionate was a poor electron donor to achieve AQDS reduction; however, denitrifying and sulfate-reducing activities carried out by both consortia promoted the reduction of AQDS via acetate accumulated from propionate oxidation. Our results suggest that microbial reduction of humic substances (HS) may play an important role during the anaerobic oxidation of organic pollutants in anaerobic environments despite the presence of alternative electron acceptors, such as sulfate and nitrate. Methane inhibition, imposed by the inclusion of AQDS as terminal electron acceptor, suggests that microbial reduction of HS may also have important implications on the global climate preservation, considering the green-house effects of methane.

  5. Comprehensive analysis of glucose and xylose metabolism in Escherichia coli under aerobic and anaerobic conditions by (13)C metabolic flux analysis.

    PubMed

    Gonzalez, Jacqueline E; Long, Christopher P; Antoniewicz, Maciek R

    2017-01-01

    Glucose and xylose are the two most abundant sugars derived from the breakdown of lignocellulosic biomass. While aerobic glucose metabolism is relatively well understood in E. coli, until now there have been only a handful of studies focused on anaerobic glucose metabolism and no (13)C-flux studies on xylose metabolism. In the absence of experimentally validated flux maps, constraint-based approaches such as MOMA and RELATCH cannot be used to guide new metabolic engineering designs. In this work, we have addressed this critical gap in current understanding by performing comprehensive characterizations of glucose and xylose metabolism under aerobic and anaerobic conditions, using recent state-of-the-art techniques in (13)C metabolic flux analysis ((13)C-MFA). Specifically, we quantified precise metabolic fluxes for each condition by performing parallel labeling experiments and analyzing the data through integrated (13)C-MFA using the optimal tracers [1,2-(13)C]glucose, [1,6-(13)C]glucose, [1,2-(13)C]xylose and [5-(13)C]xylose. We also quantified changes in biomass composition and confirmed turnover of macromolecules by applying [U-(13)C]glucose and [U-(13)C]xylose tracers. We demonstrated that under anaerobic growth conditions there is significant turnover of lipids and that a significant portion of CO2 originates from biomass turnover. Using knockout strains, we also demonstrated that β-oxidation is critical for anaerobic growth on xylose. Quantitative analysis of co-factor balances (NADH/FADH2, NADPH, and ATP) for different growth conditions provided new insights regarding the interplay of energy and redox metabolism and the impact on E. coli cell physiology.

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

    PubMed Central

    Miro, Berta; Ismail, Abdelbagi M.

    2013-01-01

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

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

    SciTech Connect

    Kosourov, S. N.; Seibert, M.

    2009-01-01

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

  8. Performance evaluation of a completely stirred anaerobic reactor treating pig manure at a low range of mesophilic conditions

    SciTech Connect

    Guo, Jianbin; Dong, Renjie; Clemens, Joachim; Wang, Wei

    2013-11-15

    Highlights: • The biogas process can run stably at 20 °C at extremely low OLR after long-term acclimation of bacteria. • A biogas plant running at 28 °C seems as efficient as that operated at 38 °C at low OLR of 1.3 g ODM L{sup −1} d{sup −1}. • Lower temperature operation is inadvisable for the commercial biogas plant running at rather high OLR. • The estimated sludge yield at 28 °C is higher than that at 38 °C. - Abstract: Many Chinese biogas plants run in the lower range of mesophilic conditions. This study evaluated the performance of a completely stirred anaerobic reactor treating pig manure at different temperatures (20, 28 and 38 °C). The start-up phase of the reactor at 20 °C was very long and extremely poor performance was observed with increasing organic loading rate (OLR). At an OLR of 4.3 g ODM L{sup −1} d{sup −1}, methane production at 28 °C was comparable (3% less) with that at 38 °C, but the risk of acidification was high at 28 °C. At low OLR (1.3 g ODM L{sup −1} d{sup −1}), the biogas process appeared stable at 28 °C and gave same methane yields as compared to the reactor operating at 38 °C. The estimated sludge yield at 28 °C was 0.065 g VSS g{sup −1} COD{sub removed,} which was higher than that at 38 °C (0.016 g VSS g{sup −1} COD{sub removed})

  9. Purification and characterization of a catalase from photosynthetic bacterium Rhodospirillum rubrum S1 grown under anaerobic conditions.

    PubMed

    Kang, Yoon-Suk; Lee, Dong-Heon; Yoon, Byoung-Jun; Oh, Duck-Chul

    2006-04-01

    The photosynthetic bacterium, Rhodospirillum rubrum S1, when grown under anaerobic conditions, generated three different types of catalases. In this study, we purified and characterized the highest molecular weight catalase from the three catalases. The total specific catalase activity of the crude cell extracts was 88 U/mg. After the completion of the final purification step, the specific activity of the purified catalase was 1,256 U/mg. The purified catalase evidenced an estimated molecular mass of 318 kDa, consisting of four identical subunits, each of 79 kDa. The purified enzyme exhibited an apparent Km value of 30.4 mM and a Vmax of 2,564 U against hydrogen peroxide. The enzyme also exhibited a broad optimal pH (5.0-9.0), and remained stable over a broad temperature range (20 degrees C-60 degrees C). It maintained 90% activity against organic solvents (ethanol/chloroform) known hydroperoxidase inhibitors, and exhibited no detectable peroxidase activity. The catalase activity of the purified enzyme was reduced to 19% of full activity as the result of the administration of 10 mM 3-amino-1,2,4-triazole, a heme-containing catalase inhibitor. Sodium cyanide, sodium azide, and hydroxylamine, all of which are known heme protein inhibitors, inhibited catalase activity by 50% at concentrations of 11.5 microM, 0.52 microM, and 0.11 microM, respectively. In accordance with these findings, the enzyme was identified as a type of monofunctional catalase.

  10. Effect of anaerobic and stationary phase growth conditions on the heat shock and oxidative stress responses in Escherichia coli K-12.

    PubMed

    Díaz-Acosta, Alondra; Sandoval, María L; Delgado-Olivares, Luis; Membrillo-Hernández, Jorge

    2006-06-01

    The natural living style of Escherichia coli occurs in the gastrointestinal tract, where most of its existence is spent under anaerobic conditions and in stationary phase of growth. Here we report on the heat shock response of E. coli K-12 cells growing in the presence or absence of oxygen. An rpoH mutant (impaired in the synthesis of the sigma(32) transcriptional factor) exhibited an increased sensitivity to heat shock but only in the exponential phase of aerobic growth, suggesting that in anaerobic growth conditions, and in aerobic stationary phase, sigma(32)-independent mechanisms are playing a prime role in protecting cells from heat stress. Our results demonstrated that sigma(S) is not involved in this protection system. Studies on the kinetics of synthesis of Heat shock proteins (Hsp) after an abrupt rise in temperature demonstrated that in the absence of oxygen, the synthesis of Hsp is triggered faster and is sustained for a longer period of time compared to aerobic growth conditions. Finally, the heated cells in the exponential phase of aerobic growth displayed a high concentration of oxidatively damaged proteins in the presence of 4 mM H(2)O(2), in sharp contrast to cultures of stationary phase or anaerobic growth.

  11. Modeling microbial ethanol production by E. coli under aerobic/anaerobic conditions: applicability to real postmortem cases and to postmortem blood derived microbial cultures.

    PubMed

    Boumba, Vassiliki A; Kourkoumelis, Nikolaos; Gousia, Panagiota; Economou, Vangelis; Papadopoulou, Chrissanthy; Vougiouklakis, Theodore

    2013-10-10

    The mathematical modeling of the microbial ethanol production under strict anaerobic experimental conditions for some bacterial species has been proposed by our research group as the first approximation to the quantification of the microbial ethanol production in cases where other alcohols were produced simultaneously with ethanol. The present study aims to: (i) study the microbial ethanol production by Escherichia coli under controlled aerobic/anaerobic conditions; (ii) model the correlation between the microbial produced ethanol and the other higher alcohols; and (iii) test their applicability in: (a) real postmortem cases that had positive BACs (>0.10 g/L) and co-detection of higher alcohols and 1-butanol during the original ethanol analysis and (b) postmortem blood derived microbial cultures under aerobic/anaerobic controlled experimental conditions. The statistical evaluation of the results revealed that the formulated models were presumably correlated to 1-propanol and 1-butanol which were recognized as the most significant descriptors of the modeling process. The significance of 1-propanol and 1-butanol as descriptors was so powerful that they could be used as the only independent variables to create a simple and satisfactory model. The current models showed a potential for application to estimate microbial ethanol - within an acceptable standard error - in various tested cases where ethanol and other alcohols have been produced from different microbes.

  12. Influence of aerobic and anaerobic conditions on survival of Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium in Luria-Bertani broth, farm-yard manure and slurry.

    PubMed

    Semenov, Alexander V; van Overbeek, Leo; Termorshuizen, Aad J; van Bruggen, Ariena H C

    2011-03-01

    The influence of aerobic and anaerobic conditions on the survival of the enteropathogens Escherichia coli O157:H7 and Salmonella serovar Typhimurium was investigated in microcosms with broth, cattle manure or slurry. These substrates were inoculated with a green fluorescent protein transformed strain of the enteropathogens at 10(7) cells g(-1) dry weight. Survival data was fitted to the Weibull model. The survival curves in aerobic conditions generally showed a concave curvature, while the curvature was convex in anaerobic conditions. The estimated survival times showed that E. coli O157:H7 survived significantly longer under anaerobic than under aerobic conditions. Survival ranged from approximately. 2 weeks for aerobic manure and slurry to more than six months for anaerobic manure at 16 °C. On average, in 56.3% of the samplings, the number of recovered E. coli O157:H7 cells by anaerobic incubation of Petri plates was significantly (p < 0.05) higher in comparison with aerobic incubation. Survival of Salmonella serovar Typhimurium was not different between aerobic and anaerobic storage of LB broth or manure as well as between aerobic and anaerobic incubation of Petri dishes. The importance of changes in microbial community and chemical composition of manure and slurry was distinguished for the survival of E. coli O157:H7 in different oxygen conditions. Copyright © 2010 Elsevier Ltd. All rights reserved.

  13. 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

  14. 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

  15. Decrease of U(VI) Immobilization Capability of the Facultative Anaerobic Strain Paenibacillus sp. JG-TB8 under Anoxic Conditions Due to Strongly Reduced Phosphatase Activity

    PubMed Central

    Reitz, Thomas; Rossberg, Andre; Barkleit, Astrid; Selenska-Pobell, Sonja; Merroun, Mohamed L.

    2014-01-01

    Interactions of a facultative anaerobic bacterial isolate named Paenibacillus sp. JG-TB8 with U(VI) were studied under oxic and anoxic conditions in order to assess the influence of the oxygen-dependent cell metabolism on microbial uranium mobilization and immobilization. We demonstrated that aerobically and anaerobically grown cells of Paenibacillus sp. JG-TB8 accumulate uranium from aqueous solutions under acidic conditions (pH 2 to 6), under oxic and anoxic conditions. A combination of spectroscopic and microscopic methods revealed that the speciation of U(VI) associated with the cells of the strain depend on the pH as well as on the aeration conditions. At pH 2 and pH 3, uranium was exclusively bound by organic phosphate groups provided by cellular components, independently on the aeration conditions. At higher pH values, a part (pH 4.5) or the total amount (pH 6) of the dissolved uranium was precipitated under oxic conditions in a meta-autunite-like uranyl phosphate mineral phase without supplying an additional organic phosphate substrate. In contrast to that, under anoxic conditions no mineral formation was observed at pH 4.5 and pH 6, which was clearly assigned to decreased orthophosphate release by the cells. This in turn was caused by a suppression of the indigenous phosphatase activity of the strain. The results demonstrate that changes in the metabolism of facultative anaerobic microorganisms caused by the presence or absence of oxygen can decisively influence U(VI) biomineralization. PMID:25157416

  16. Effect of anaerobic soil disinfestation and vermicompost on soilborne phytopathogenic agents under tree-crop nursery conditions

    USDA-ARS?s Scientific Manuscript database

    Anaerobic soil disinfestation (ASD) is a fumigation-independent management strategy for controlling soilborne pathogens. Walnut nurseries currently employ preplant fumigation to control soilborne phytopathogens and weeds, and may be amenable to use ASD instead. We investigated the potential of ASD a...

  17. Comparison of different conditions, substrates and operation modes by dynamic simulation of a full-scale anaerobic SBR plant.

    PubMed

    Rönner-Holm, S G E; Zak, A; Holm, N C

    2012-01-01

    Simulation studies for a full-scale anaerobic unit of a wastewater treatment plant (WWTP) were performed using the anaerobic digestion model no. 1 (ADM1). The anaerobic full-scale plant consists of one mesophilic and one thermophilic digester, operated in an anaerobic sequential batch reactor (ASBR) mode, and sludge enrichment reactors (SER) for each digester. The digesters are fed with a mixture of vegetable waste and process wastewater from the food factory. Characteristics such as COD(total), N(total) and NH(4)-N concentrations in the influent and effluent of the digester and SERs were measured and used for input fractionation. Parameters such as level, pH, biogas amount and composition in the digester were measured online and used for calibration. For simulation studies, different temperatures and operation modes with varying chemical oxygen demand (COD) input loads corresponding to feedstocks such as fruits, vegetables and grain were analysed and compared. Higher gas production and digestion efficiency in the thermophilic reactor and in shorter cycles were found and confirmed at full scale. Serial operation mode increased the gas production, but pH inhibition occurred earlier. Feeding only biosolids into digester I and the effluent of digester I together with process water into digester II further improved gas production in serial operation mode.

  18. Biostimulation of anaerobic BTEX biodegradation under fermentative methanogenic conditions at source-zone groundwater contaminated with a biodiesel blend (B20).

    PubMed

    Ramos, Débora Toledo; da Silva, Márcio Luis Busi; Chiaranda, Helen Simone; Alvarez, Pedro J J; Corseuil, Henry Xavier

    2013-06-01

    Field experiments were conducted to assess the potential for anaerobic biostimulation to enhance BTEX biodegradation under fermentative methanogenic conditions in groundwater impacted by a biodiesel blend (B20, consisting of 20 % v/v biodiesel and 80 % v/v diesel). B20 (100 L) was released at each of two plots through an area of 1 m(2) that was excavated down to the water table, 1.6 m below ground surface. One release was biostimulated with ammonium acetate, which was added weekly through injection wells near the source zone over 15 months. The other release was not biostimulated and served as a baseline control simulating natural attenuation. Ammonium acetate addition stimulated the development of strongly anaerobic conditions, as indicated by near-saturation methane concentrations. BTEX removal began within 8 months in the biostimulated source zone, but not in the natural attenuation control, where BTEX concentrations were still increasing (due to source dissolution) 2 years after the release. Phylogenetic analysis using quantitative PCR indicated an increase in concentration and relative abundance of Archaea (Crenarchaeota and Euryarchaeota), Geobacteraceae (Geobacter and Pelobacter spp.) and sulfate-reducing bacteria (Desulfovibrio, Desulfomicrobium, Desulfuromusa, and Desulfuromonas) in the biostimulated plot relative to the control. Apparently, biostimulation fortuitously enhanced the growth of putative anaerobic BTEX degraders and associated commensal microorganisms that consume acetate and H2, and enhance the thermodynamic feasibility of BTEX fermentation. This is the first field study to suggest that anaerobic-methanogenic biostimulation could enhance source zone bioremediation of groundwater aquifers impacted by biodiesel blends.

  19. Biochemical and Structural Studies of NADH-Dependent FabG Used To Increase the Bacterial Production of Fatty Acids under Anaerobic Conditions

    PubMed Central

    Javidpour, Pouya; Pereira, Jose H.; Goh, Ee-Been; McAndrew, Ryan P.; Ma, Suzanne M.; Friedland, Gregory D.; Keasling, Jay D.; Chhabra, Swapnil R.; Adams, Paul D.

    2014-01-01

    Major efforts in bioenergy research have focused on producing fuels that can directly replace petroleum-derived gasoline and diesel fuel through metabolic engineering of microbial fatty acid biosynthetic pathways. Typically, growth and pathway induction are conducted under aerobic conditions, but for operational efficiency in an industrial context, anaerobic culture conditions would be preferred to obviate the need to maintain specific dissolved oxygen concentrations and to maximize the proportion of reducing equivalents directed to biofuel biosynthesis rather than ATP production. A major concern with fermentative growth conditions is elevated NADH levels, which can adversely affect cell physiology. The purpose of this study was to identify homologs of Escherichia coli FabG, an essential reductase involved in fatty acid biosynthesis, that display a higher preference for NADH than for NADPH as a cofactor. Four potential NADH-dependent FabG variants were identified through bioinformatic analyses supported by crystallographic structure determination (1.3- to 2.0-Å resolution). In vitro assays of cofactor (NADH/NADPH) preference in the four variants showed up to ∼35-fold preference for NADH, which was observed with the Cupriavidus taiwanensis FabG variant. In addition, FabG homologs were overexpressed in fatty acid- and methyl ketone-overproducing E. coli host strains under anaerobic conditions, and the C. taiwanensis variant led to a 60% higher free fatty acid titer and 75% higher methyl ketone titer relative to the titers of the control strains. With further engineering, this work could serve as a starting point for establishing a microbial host strain for production of fatty acid-derived biofuels (e.g., methyl ketones) under anaerobic conditions. PMID:24212572

  20. 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 ...

  1. Tenax extraction for exploring rate-limiting factors in methyl-β-cyclodextrin enhanced anaerobic biodegradation of PAHs under denitrifying conditions in a red paddy soil.

    PubMed

    Sun, Mingming; Ye, Mao; Hu, Feng; Li, Huixin; Teng, Ying; Luo, Yongming; Jiang, Xin; Kengara, Fredrick Orori

    2014-01-15

    The effectiveness of anaerobic bioremediation systems for PAH-contaminated soil may be constrained by low contaminants bioaccessibility due to limited aqueous solubility and lack of suitable electron acceptors. Information on what is the rate-limiting factor in bioremediation process is of vital importance in the decision in what measures can be taken to assist the biodegradation efficacy. In the present study, four different microcosms were set to study the effect of methyl-β-cyclodextrin (MCD) and nitrate addition (N) on PAHs biodegradation under anaerobic conditions in a red paddy soil. Meanwhile, sequential Tenax extraction combined with a first-three-compartment model was employed to evaluate the rate-limiting factors in MCD enhanced anaerobic biodegradation of PAHs. Microcosms with both 1% (w/w) MCD and 20mM N addition produced maximum biodegradation of total PAHs of up to 61.7%. It appears rate-limiting factors vary with microcosms: low activity of degrading microorganisms is the vital rate-limiting factor for control and MCD addition treatments (CK and M treatments); and lack of bioaccessible PAHs is the main rate-limiting factor for nitrate addition treatments (N and MN treatments). These results have practical implications for site risk assessment and cleanup strategies.

  2. Oxygen-Insensitive Nitroreductases NfsA and NfsB of Escherichia coli Function under Anaerobic Conditions as Lawsone-Dependent Azo Reductases

    PubMed Central

    Rau, Jörg; Stolz, Andreas

    2003-01-01

    Quinones can function as redox mediators in the unspecific anaerobic reduction of azo compounds by various bacterial species. These quinones are enzymatically reduced by the bacteria and the resulting hydroquinones then reduce in a purely chemical redox reaction the azo compounds outside of the cells. Recently, it has been demonstrated that the addition of lawsone (2-hydroxy-1,4-naphthoquinone) to anaerobically incubated cells of Escherichia coli resulted in a pronounced increase in the reduction rates of different sulfonated and polymeric azo compounds. In the present study it was attempted to identify the enzyme system(s) responsible for the reduction of lawsone by E. coli and thus for the lawsone-dependent anaerobic azo reductase activity. An NADH-dependent lawsone reductase activity was found in the cytosolic fraction of the cells. The enzyme was purified by column chromatography and the amino-terminal amino acid sequence of the protein was determined. The sequence obtained was identical to the sequence of an oxygen-insensitive nitroreductase (NfsB) described earlier from this organism. Subsequent biochemical tests with the purified lawsone reductase activity confirmed that the lawsone reductase activity detected was identical with NfsB. In addition it was proven that also a second oxygen-insensitive nitroreductase of E. coli (NfsA) is able to reduce lawsone and thus to function under adequate conditions as quinone-dependent azo reductase. PMID:12788749

  3. Biodegradation of polyacrylamide by anaerobic digestion under mesophilic condition and its performance in actual dewatered sludge system.

    PubMed

    Dai, Xiaohu; Luo, Fan; Yi, Jing; He, Qunbiao; Dong, Bin

    2014-02-01

    Polyacrylamide (PAM) used in sludge dewatering widely exists in high-solid anaerobic digestion. Degradation of polyacrylamide accompanied with accumulation of its toxic monomer is important to disposition of biogas residues. The potential of anaerobic digestion activity in microbial utilization of PAM was investigated in this study. The results indicated that the utilization rate of PAM (as nitrogen source) was influenced by accumulation of ammonia, while cumulative removal of amide group was accorded with zeroth order reaction in actual dewatered system. The adjoining amide group can combined into ether group after biodegradation. PAM can be broken down in different position of its carbon chain backbone. In actual sludge system, the hydrolytic PAM was liable to combined tyrosine-rich protein to form colloid complex, and then consumed as carbon source to form monomer when easily degradable organics were exhausted. The accumulation of acrylamide was leveled off ultimately, accompanied with the yield of methane. Copyright © 2013 Elsevier Ltd. All rights reserved.

  4. Impact of high external circulation ratio on the performance of anaerobic reactor treating coal gasification wastewater under thermophilic condition.

    PubMed

    Jia, Shengyong; Han, Hongjun; Zhuang, Haifeng; Hou, Baolin; Li, Kun

    2015-09-01

    A laboratory-scale external circulation anaerobic reactor (ECAR) was developed to treat actual coal gasification wastewater. The external circulation ratio (R) was selected as the main operating variable for analysis. From the results, with the hydraulic retention time of 50h, pH > 8.0 and R of 3, the COD, total phenols, volatile phenol and NH4(+)-N removal efficiencies were remarkably increased to 10 ± 2%, 22 ± 5%, 18 ± 1%, and -1 ± 2%, respectively. Besides, increasing R resulted in more transformation from bound extracellular polymeric substances (EPS) to free EPS in the liquid and the particle size distribution of anaerobic granular sludge accumulated in the middle size range of 1.0-2.5mm. Results showed the genus Saccharofermentans dominanted in the ECAR and the bacterial community shift was observed at different external circulation ratio, influencing the pollutants removal profoundly.

  5. Positive feedback of crop residue incorporation on dissolved organic carbon contents under anaerobic conditions in temperate rice paddy soils

    NASA Astrophysics Data System (ADS)

    Said-Pullicino, Daniel; Sodano, Marcella; Bertora, Chiara; Lerda, Cristina; Sacco, Dario; Celi, Luisella

    2016-04-01

    Rice paddy soils are generally characterized by large concentrations and fluxes of DOC in comparison to other ecosystems. Our recent studies have shown that the combination of relatively high pore-water DOC concentrations under anoxic soil conditions (>10-20 mg C l-1) and important percolation fluxes of water during field flooding may contribute significant organic C inputs into the subsoil (18-51 g C m-2) over the cropping season. Crop residues incorporated into the soil after harvest represent the main input of organic C into paddy soils, returning about 200-300 g C m-2 y-1 in single-cropped rice paddies. The anaerobic decomposition of these residues may supply important amounts of DOC to soil pore waters. Moreover, the supply of electron donors with the input of residue-derived labile OM may further increase DOC contents by stimulating the microbially-catalyzed reductive dissolution of Fe and Mn oxyhydroxides under anoxic conditions, and release of DOC previously stabilized on the mineral matrix (i.e. positive feedback). This could have important implications on organic C inputs into the subsoil as well as substrate availability for methane production. We therefore hypothesized that crop residue management practices that influence the amount of labile organic matter present in the soil at the time of field flooding may strongly influence soil solution DOC concentrations as well as the positive feedback on the release of soil-derived DOC. We tested this hypothesis at field-scale by evaluating variations in the contents and quality of DOC above and beneath the plough pan over the cropping season as a function of crop residue management practices involving: tillage and crop residue incorporation in spring (SPR), tillage and crop residue incorporation in spring, dry seeding and 1 month delayed flooding (DRY), tillage and crop residue incorporation in autumn (AUT), and straw removal after harvest and tillage in spring (REM). Moreover, we linked changes in DOC

  6. Anaerobic respiration and antioxidant responses of Corythucha ciliata (Say) adults to heat-induced oxidative stress under laboratory and field conditions.

    PubMed

    Ju, Rui-Ting; Wei, He-Ping; Wang, Feng; Zhou, Xu-Hui; Li, Bo

    2014-03-01

    High temperature often induces oxidative stress and antioxidant response in insects. This phenomenon has been well documented under controlled laboratory conditions, but whether it happens under fluctuating field conditions is largely unknown. In this study, we used an invasive lace bug (Corythucha ciliata) as a model species to compare the effects of controlled thermal treatments (2 h at 33-43 °C with 2 °C intervals in the laboratory) and naturally fluctuating thermal conditions (08:00-14:00 at 2-h intervals (29.7-37.2 °C) on a hot summer day in a field in Shanghai, China) on lipid peroxidation (malondialdehyde (MDA) was the marker) and anaerobic respiration (lactate dehydrogenase (LDH) was the marker), as well as superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), and glutathione reductase (GR). The results show that MDA concentration increased significantly in response to heat stresses with similar trend in the laboratory and field. LDH activities did not significantly vary across temperatures in the laboratory-exposed individuals, but they significantly increased by rising temperature in the field. The activities or concentrations of SOD, CAT, GSH, and GR all significantly increased with increasing temperature in the two populations. These findings indicate that high temperature induces oxidative stress, resulting in high anaerobic respiration and antioxidant defenses in C. ciliata under both the laboratory and field conditions, which likely provide a defense mechanism against oxidative damage due to the accumulation of ROS.

  7. Co-conditioning of the anaerobic digested sludge of a municipal wastewater treatment plant with alum sludge: benefit of phosphorus reduction in reject water.

    PubMed

    Yang, Y; Zhao, Y Q; Babatunde, A O; Kearney, P

    2007-12-01

    In this study, alum sludge was introduced to co-conditioning and dewatering with an anaerobic digested sludge from a municipal wastewater treatment plant, to examine the role of the alum sludge in improving the dewaterbility of the mixed sludge and also in immobilizing phosphorus in the reject water. Experiments have demonstrated that the optimal mix ratio for the two sludges is 2:1 (anaerobic digested sludge:alum sludge: volume basis), and this can bring approximately 99% phosphorus reduction in the reject water through the adsorption of phosphorus by alum in the sludge. The phosphorus loading in wastewater treatment plants is itself derived from the recycling of reject water during the wastewater treatment process. Consequently, this co-conditioning and dewatering strategy can achieve a significant reduction in phosphorus loading in wastewater treatment plants. In addition, the use of the alum sludge has been shown to beneficially enhance the dewaterability of the resultant mixed sludge, by decreasing both the specific resistance to filtration and the capillary suction time. This is attributed to the alum sludge acting in charge neutralization and/or as adsorbent for phosphate in the aqueous phase of the sludge. Experiments have also demonstrated that the optimal polymer (Superfloc C2260, Cytec, Botlek, Netherlands) dose for the anaerobic digested sludge was 120 mg/L, while the optimal dose for the mixed sludge (mix ratio 2:1) was 15 mg/L, highlighting a huge savings in polymer addition. Therefore, from the technical perspective, the co-conditioning and dewatering strategy can be viewed as a "win-win" situation. However, for its full-scale application, integrated cost-effective analysis of process capabilities, sludge transport, increased cake disposal, additional administration, polymer saving, and so on, should be factored in.

  8. A new approach for concurrently improving performance of South Korean food waste valorization and renewable energy recovery via dry anaerobic digestion under mesophilic and thermophilic conditions.

    PubMed

    Nguyen, Dinh Duc; Yeop, Jeong Seong; Choi, Jaehoon; Kim, Sungsu; Chang, Soon Woong; Jeon, Byong-Hun; Guo, Wenshan; Ngo, Huu Hao

    2017-08-01

    Dry semicontinuous anaerobic digestion (AD) of South Korean food waste (FW) under four solid loading rates (SLRs) (2.30-9.21kg total solids (TS)/m(3)day) and at a fixed TS content was compared between two digesters, one each under mesophilic and thermophilic conditions. Biogas production and organic matter reduction in both digesters followed similar trends, increasing with rising SLR. Inhibitor (intermediate products of the anaerobic fermentation process) effects on the digesters' performance were not observed under the studied conditions. In all cases tested, the digesters' best performance was achieved at the SLR of 9.21kg TS/m(3)day, with 74.02% and 80.98% reduction of volatile solids (VS), 0.87 and 0.90m(3) biogas/kg VSremoved, and 0.65 (65% CH4) and 0.73 (60.02% CH4) m(3) biogas/kg VSfed, under mesophilic and thermophilic conditions, respectively. Thermophilic dry AD is recommended for FW treatment in South Korea because it is more efficient and has higher energy recovery potential when compared to mesophilic dry AD. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. The anaerobic endurance of elite soccer players improved after a high-intensity training intervention in the 8-week conditioning program.

    PubMed

    Sporis, Goran; Ruzic, Lana; Leko, Goran

    2008-03-01

    The purpose of this study was to evaluate changes in anaerobic endurance in elite First-league soccer players throughout 2 consecutive seasons, in 2 phases, with and without high-intensity situational drills. Eighteen soccer players were tested before and after the 8-week summer conditioning and again in the next season. The measured variables included 300-yard shuttle run test, maximal heart rate, and maximal blood lactate at the end of the test. During the first phase of the study, the traditional sprint training was performed only 2 x weeks and consisted of 15 bouts of straight-line sprinting. In the second year the 4 x 4 min drills at an intensity of 90-95% of HRmax, separated by periods of 3-minute technical drills at 55-65% of HRmax were introduced. Statistical significance was set at P conditioning program conducted during the first year of the study did not elicit an improvement in anaerobic endurance as recorded in the 300-yard shuttle run test. After the intervention, the overall test running time improved significantly (55.74 +/- 1.63 s vs. 56.99 +/- 1.64 s; P < 0.05) with the maximal blood lactate at the end of the test significantly greater (15.4 +/- 1.23 mmol.L vs. 13.5 +/- 1.12 mmol.L. P < 0.01). As a result, this study showed some indication that situational high-intensity task training was more efficient than straight-line sprinting in improving anaerobic endurance measured by the 300-yard shuttle run test.

  10. Relationship between the physiology of Enterobacter agglomerans CNCM 1210 grown anaerobically on glycerol and the culture conditions.

    PubMed

    Barbirato, F; Bories, A

    1997-01-01

    In a preliminary study, levels of activity of enzymes involved in anaerobic glycerol catabolism by Enterobacter agglomerans grown in batch cultures regulated in a pH range of 6.5-8.0 were monitored. That study showed that activities of key enzymes of the downstream metabolism of glycerol--glyceradehyde-3-phosphate dehydrogenase (GAP-DH), lactate dehydrogenase and pyruvate formate lyase--were strongly dependent on the culture pH. To investigate the influence of pH on the physiology of the strain, E. agglomerans was grown anaerobically in a continuous culture supplied with glycerol as the sole carbon source and regulated at pH 8. A complete biochemical analysis was performed and was compared with that previously described for the continuous culture regulated at pH 7. A limitation of the glycolytic flux at the level of GAP-DH was demonstrated at high dilution rate, resulting in an overflow metabolism through the 1,3-propanediol formation pathway. Increasing the specific rate of glycerol consumption also resulted in enhanced lactate production due to limitation by the pyruvate decarboxylation step. Finally, changing the culture pH significantly modified the enzymatic profile of E. agglomerans, and it enabled the stability of the culture to be increased by preventing the accumulation in the fermentation broth of 3-hydroxypropionaldehyde, an inhibitory metabolite, when the glycerol supply was suddenly increased.

  11. Unsaturated fatty acids from food and in the growth medium improve growth of Bacillus cereus under cold and anaerobic conditions.

    PubMed

    de Sarrau, Benoît; Clavel, Thierry; Zwickel, Nicolas; Despres, Jordane; Dupont, Sébastien; Beney, Laurent; Tourdot-Maréchal, Raphaëlle; Nguyen-The, Christophe

    2013-12-01

    In a chemically defined medium and in Luria broth, cold strongly reduced maximal population density of Bacillus cereus ATCC 14579 in anaerobiosis and caused formation of filaments. In cooked spinach, maximal population density of B. cereus in anaerobiosis was the same at cold and optimal temperatures, with normal cell divisions. The lipid containing fraction of spinach, but not the hydrophilic fraction, restored growth of B. cereus under cold and anaerobiosis when added to the chemically defined medium. This fraction was rich in unsaturated, low melting point fatty acids. Addition of phosphatidylcholine containing unsaturated, low melting point, fatty acids similarly improved B. cereus anaerobic growth at cold temperature. Addition of hydrogenated phosphatidylcholine containing saturated, high melting point, fatty acids did not modify growth. Fatty acids from phospholipids, from spinach and from hydrogenated phosphatidylcholine, although normally very rare in B. cereus, were inserted in the bacterium membrane. Addition of phospholipids rich in unsaturated fatty acids to cold and anaerobic cultures, increased fluidity of B. cereus membrane lipids, to the same level as those from B. cereus normally cold adapted, i.e. grown aerobically at 15 °C. B. cereus is therefore able to use external fatty acids from foods or from the growth medium to adapt its membrane to cold temperature under anaerobiosis, and to recover the maximal population density achieved at optimal temperature.

  12. Biological sulfate reduction in the acidogenic phase of anaerobic digestion under dissimilatory Fe (III)--reducing conditions.

    PubMed

    Zhang, Jingxin; Zhang, Yaobin; Chang, Jinghui; Quan, Xie; Li, Qi

    2013-04-15

    In this study, a novel approach was developed for sulfate - containing wastewater treatment via dosing Fe₂O₃ in a two - stage anaerobic reactor (A1, S1). The addition of Fe₂O₃ in its second stage i.e. acidogenic sulfate-reducing reactor (S1) resulted in microbial reduction of Fe (III), which significantly enhanced the biological sulfate reduction. In reactor S1, increasing influent sulfate concentration to 1400 mg/L resulted in a higher COD removal (27.3%) and sulfate reduction (57.9%). In the reference reactor without using Fe₂O₃ (S2), the COD and sulfate removal were 15.6% and 29%, respectively. The combined performance of the two-stage anaerobic reactor (A1, S1) also showed a higher COD removal of 74.2%. Denaturing gradient gel electrophoresis (DGGE) and phylogenetic analysis showed that the dominant bacteria with high similarity to IRB species as well as sulfate reducer Desulfovibrio and acidogenic bacteria (AB) were enriched in S1. Quantitative Polymerase Chain Reaction (qPCR) analysis presented a higher proportion of sulfate reducer Desulfovibrio marrakechensis and Fe (III) reducer Iron-reducing bacteria HN54 in S1. Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. Cooperative Actions of CRP-cAMP and FNR Increase the Fosfomycin Susceptibility of Enterohaemorrhagic Escherichia coli (EHEC) by Elevating the Expression of glpT and uhpT under Anaerobic Conditions

    PubMed Central

    Kurabayashi, Kumiko; Tanimoto, Koichi; Tomita, Haruyoshi; Hirakawa, Hidetada

    2017-01-01

    Bacterial infections to anaerobic site are often hard to be treated because the activity of most of antimicrobials decreases under anaerobic conditions. However, fosfomycin rather provides a greater activity under anaerobic conditions than aerobic conditions. Previously, we found that expression of glpT and uhpT, fosfomycin symporters in enterohaemorrhagic Escherichia coli (EHEC) was upregulated by FNR, a global regulator during the anaerobiosis of the bacterium, which led to increased uptake and susceptibility to this drug. In this study, we showed that expression of glpT and uhpT is induced by CRP-cAMP, the regulator complex under both aerobic and anaerobic conditions. The activity of CRP-cAMP in EHEC was elevated under anaerobic conditions because levels of both CRP and cAMP were higher in the cells when grown anaerobically than those when grown aerobically. Results of expression study using mutants indicated that CRP-cAMP is indispensable for expression of glpT but not uhpT—whereas that of uhpT requires UhpA that is the response regulator composing of two-component system with the sensor kinase, UhpB. The CRP-cAMP protein bound to a region that overlaps RNA polymerase binding site for glpT and region upstream of UhpA binding site for uhpT. FNR bound to a region further upstream of CRP-cAMP binding site on region upstream of the glpT gene. These combined results suggested that increased antibacterial activity of fosfomycin to EHEC under anaerobic conditions is due to activation of FNR and increment of CRP-cAMP activity. Then, FNR enhances the expression of glpT activated by CRP-cAMP while CRP-cAMP and FNR cooperatively aids the action of UhpA to express uhpT to maximum level. PMID:28360903

  14. Complete anaerobic mineralization of pentachlorophenol (PCP) under continuous flow conditions by sequential combination of PCP-dechlorinating and phenol-degrading consortia.

    PubMed

    Li, Zhiling; Yang, Suyin; Inoue, Yasushi; Yoshida, Naoko; Katayama, Arata

    2010-12-01

    Complete mineralization of 50 µM of pentachlorophenol (PCP) was achieved anaerobically under continuous flow conditions using two columns connected in series with a hydraulic retention time of 14.2 days, showing the highest reported mineralization rate yet of 3.5 µM day(-1). The first column, when injected with a reductive PCP dechlorinating consortium, dechlorinated PCP to mainly phenol and traces of 3-chlorophenol (3-CP) using lactate supplied continuously as an electron donor. The second column, with an anaerobic phenol degrading consortium, decomposed phenol and 3-CP under iron-reducing conditions with substantial fermentative degradation of organic compounds. When 20 mM of lactate was introduced into the first column, the phenol degradation activity of the second column was lost in a short period of time, because the amorphous Fe(III) oxide (FeOOH) that had been packed in the column before use was depleted by lactate metabolites, such as acetate and propionate, flowing into the second column from the first column. The complete mineralization of PCP was maintained for a long period by reducing the lactate concentration to 4 mM, effectively extending the longevity of second-column activity with no depletion of FeOOH for more than 200 pore volumes (corresponding to 3,000 days). The carbon balance showed that 50 µM PCP and 4 mM lactate in the influent had transformed to CO(2) (81%) and CH(4) (3%) and had contributed to biomass growth (8%). A comparison of the microbial consortia introduced into the columns and those flowing out from the columns suggested that the introduced population did not flow out during the experiments, although the microbial composition of the phenol column was considered to be affected by the inflow of microbes from the PCP dechlorination column. These results suggest that a sequential combination of reductive dechlorinating and anaerobic oxidizing consortia is useful for anaerobic remediation of chlorinated aromatic compounds in

  15. Isolation of Three New Surface Layer Protein Genes (slp) from Lactobacillus brevis ATCC 14869 and Characterization of the Change in Their Expression under Aerated and Anaerobic Conditions

    PubMed Central

    Jakava-Viljanen, Miia; Åvall-Jääskeläinen, Silja; Messner, Paul; Sleytr, Uwe B.; Palva, Airi

    2002-01-01

    Two new surface layer (S-layer) proteins (SlpB and SlpD) were characterized, and three slp genes (slpB, slpC, and slpD) were isolated, sequenced, and studied for their expression in Lactobacillus brevis neotype strain ATCC 14869. Under different growth conditions, L. brevis strain 14869 was found to form two colony types, smooth (S) and rough (R), and to express the S-layer proteins differently. Under aerobic conditions R-colony type cells produced SlpB and SlpD proteins, whereas under anaerobic conditions S-colony type cells synthesized essentially only SlpB. Anaerobic and aerated cultivations of ATCC 14869 cells in rich medium also resulted in S-layer protein patterns similar to those of the S- and R-colony type cells, respectively. Electron microscopy suggested the presence of only a single S-layer with an oblique structure on the cells of both colony forms. The slpB and slpC genes were located adjacent to each other, whereas the slpD gene was not closely linked to the slpB-slpC gene region. Northern analyses confirmed that both slpB and slpD formed a monocistronic transcription unit and were effectively expressed, but slpD expression was induced under aerated conditions. slpC was a silent gene under the growth conditions tested. The amino acid contents of all the L. brevis ATCC 14869 S-layer proteins were typical of S-layer proteins, whereas their sequence similarities with other S-layer proteins were negligible. The interspecies identity of the L. brevis S-layer proteins was mainly restricted to the N-terminal regions of those proteins. Furthermore, Northern analyses, expression of a PepI reporter protein under the control of the slpD promoter, and quantitative real-time PCR analysis of slpD expression under aerated and anaerobic conditions suggested that, in L. brevis ATCC 14869, the variation of S-layer protein content involves activation of transcription by a soluble factor rather than DNA rearrangements that are typical for most of the S-layer phase

  16. Operating conditions influence microbial community structures, elimination of the antibiotic resistance genes and metabolites during anaerobic digestion of cow manure in the presence of oxytetracycline.

    PubMed

    Turker, Gokhan; Akyol, Çağrı; Ince, Orhan; Aydin, Sevcan; Ince, Bahar

    2017-08-29

    The way that antibiotic residues in manure follow is one of the greatest concerns due to its potential negative impacts on microbial communities, the release of metabolites and antibiotic resistant genes (ARGs) into the nature and the loss of energy recovery in anaerobic digestion (AD) systems. This study evaluated the link between different operating conditions, the biodegradation of oxytetracycline (OTC) and the formation of its metabolites and ARGs in anaerobic digesters treating cow manure. Microbial communities and ARGs were determined through the use of quantitative real-time PCR. The biodegradation of OTC and occurrence of metabolites were determined using UV-HPLC and LC/MS/MS respectively. The maximum quantity of resistance genes was also examined at the beginning of AD tests and concentration was in the order of: tetM >tetO. The numbers of ARGs were always higher at high volatile solids (VS) content and high mixing rate. The results of the investigation revealed that relationship between mixing rate and VS content plays a crucial role for elimination of ARGs, OTC and metabolites. This can be attributed to high abundance of microorganisms due to high VS content and their increased contact with elevated mixing rate. An increased interaction between microorganisms triggers the promotion of ARGs. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Sodium nitrite-mediated killing of the major cystic fibrosis pathogens Pseudomonas aeruginosa, Staphylococcus aureus, and Burkholderia cepacia under anaerobic planktonic and biofilm conditions.

    PubMed

    Major, Tiffany A; Panmanee, Warunya; Mortensen, Joel E; Gray, Larry D; Hoglen, Niel; Hassett, Daniel J

    2010-11-01

    A hallmark of airways in patients with cystic fibrosis (CF) is highly refractory, chronic infections by several opportunistic bacterial pathogens. A recent study demonstrated that acidified sodium nitrite (A-NO(2)(-)) killed the highly refractory mucoid form of Pseudomonas aeruginosa, a pathogen that significantly compromises lung function in CF patients (S. S. Yoon et al., J. Clin. Invest. 116:436-446, 2006). Therefore, the microbicidal activity of A-NO(2)(-) (pH 6.5) against the following three major CF pathogens was assessed: P. aeruginosa (a mucoid, mucA22 mutant and a sequenced nonmucoid strain, PAO1), Staphylococcus aureus USA300 (methicillin resistant), and Burkholderia cepacia, a notoriously antibiotic-resistant organism. Under planktonic, anaerobic conditions, growth of all strains except for P. aeruginosa PAO1 was inhibited by 7.24 mM (512 μg ml(-1) NO(2)(-)). B. cepacia was particularly sensitive to low concentrations of A-NO(2)(-) (1.81 mM) under planktonic conditions. In antibiotic-resistant communities known as biofilms, which are reminiscent of end-stage CF airway disease, A-NO(2)(-) killed mucoid P. aeruginosa, S. aureus, and B. cepacia; 1 to 2 logs of cells were killed after a 2-day incubation with a single dose of ∼15 mM A-NO(2)(-). Animal toxicology and phase I human trials indicate that these bactericidal levels of A-NO(2)(-) can be easily attained by aerosolization. Thus, in summary, we demonstrate that A-NO(2)(-) is very effective at killing these important CF pathogens and could be effective in other infectious settings, particularly under anaerobic conditions where bacterial defenses against the reduction product of A-NO(2)(-), nitric oxide (NO), are dramatically reduced.

  18. 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.

  19. 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.

  20. Anaerobic treatment of rice winery wastewater in an upflow filter packed with steel slag under different hydraulic loading conditions.

    PubMed

    Jo, Yeadam; Kim, Jaai; Hwang, Seokhwan; Lee, Changsoo

    2015-10-01

    Rice-washing drainage (RWD), a strong organic wastewater, was anaerobically treated using an upflow filter filled with blast-furnace slag. The continuous performance of the reactor was examined at varying hydraulic retention times (HRTs). The reactor achieved 91.7% chemical oxygen demand removal (CODr) for a 10-day HRT (0.6 g COD/Ld organic loading rate) and maintained fairly stable performance until the HRT was shortened to 2.2 days (CODr > 84%). Further decreases in HRT caused process deterioration (CODr < 50% and pH < 5.5 for a 0.7-day HRT). The methane production rate increased with decreasing HRT to reach the peak level for a 1.3-day HRT, whereas the yield was significantly greater for 3.4-day or longer HRTs. The substrate removal and methane production kinetics were successfully evaluated, and the generated kinetic models produced good performance predictions. The methanogenic activity of the reactor likely relies on the filter biofilm, with Methanosaeta being the main driver. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. Homeostasis of metabolites in Escherichia coli on transition from anaerobic to aerobic conditions and the transient secretion of pyruvate

    PubMed Central

    Yasid, Nur Adeela; Rolfe, Matthew D.; Green, Jeffrey

    2016-01-01

    We have developed a method for rapid quenching of samples taken from chemostat cultures of Escherichia coli that gives reproducible and reliable measurements of extracellular and intracellular metabolites by 1H NMR and have applied it to study the major central metabolites during the transition from anaerobic to aerobic growth. Almost all metabolites showed a gradual change after perturbation with air, consistent with immediate inhibition of pyruvate formate-lyase, dilution of overflow metabolites and induction of aerobic enzymes. Surprisingly, although pyruvate showed almost no change in intracellular concentration, the extracellular concentration transiently increased. The absence of intracellular accumulation of pyruvate suggested that one or more glycolytic enzymes might relocate to the cell membrane. To test this hypothesis, chromosomal pyruvate kinase (pykF) was modified to express either PykF-green fluorescent protein or PykF-FLAG fusion proteins. Measurements showed that PykF-FLAG relocates to the cell membrane within 5 min of aeration and then slowly returns to the cytoplasm, suggesting that on aeration, PykF associates with the membrane to facilitate secretion of pyruvate to maintain constant intracellular levels. PMID:27853594

  2. An intestinal parasitic protist, Entamoeba histolytica, possesses a non-redundant nitrogen fixation-like system for iron-sulfur cluster assembly under anaerobic conditions.

    PubMed

    Ali, Vahab; Shigeta, Yasuo; Tokumoto, Umechiyo; Takahashi, Yasuhiro; Nozaki, Tomoyoshi

    2004-04-16

    We have characterized the iron-sulfur (Fe-S) cluster formation in an anaerobic amitochondrial protozoan parasite, Entamoeba histolytica, in which Fe-S proteins play an important role in energy metabolism and electron transfer. A genomewide search showed that E. histolytica apparently possesses a simplified and non-redundant NIF (nitrogen fixation)-like system for the Fe-S cluster formation, composed of only a catalytic component, NifS, and a scaffold component, NifU. Amino acid alignment and phylogenetic analyses revealed that both amebic NifS and NifU (EhNifS and EhNifU, respectively) showed a close kinship to orthologs from epsilon-proteobacteria, suggesting that both of these genes were likely transferred by lateral gene transfer from an ancestor of epsilon-proteobacteria to E. histolytica. The EhNifS protein expressed in E. coli was present as a homodimer, showing cysteine desulfurase activity with a very basic optimum pH compared with NifS from other organisms. Eh-NifU protein existed as a tetramer and contained one stable [2Fe-2S]2+ cluster per monomer, revealed by spectroscopic and iron analyses. Fractionation of the whole parasite lysate by anion exchange chromatography revealed three major cysteine desulfurase activities, one of which corresponded to the EhNifS protein, verified by immunoblot analysis using the specific EhNifS antibody; the other two peaks corresponded to methionine gamma-lyase and cysteine synthase. Finally, ectopic expression of the EhNifS and EhNifU genes successfully complemented, under anaerobic but not aerobic conditions, the growth defect of an Escherichia coli strain, in which both the isc and suf operons were deleted, suggesting that EhNifS and EhNifU are necessary and sufficient for Fe-S clusters of non-nitrogenase Fe-S proteins to form under anaerobic conditions. This is the first demonstration of the presence and biological significance of the NIF-like system in eukaryotes.

  3. TM0486 from the hyperthermophilic anaerobe Thermotoga maritima is a thiamin-binding protein involved in response of the cell to oxidative conditions.

    PubMed

    Dermoun, Zorah; Foulon, Amélie; Miller, Mitchell D; Harrington, Daniel J; Deacon, Ashley M; Sebban-Kreuzer, Corinne; Roche, Philippe; Lafitte, Daniel; Bornet, Olivier; Wilson, Ian A; Dolla, Alain

    2010-07-16

    The COG database was used for a comparative genome analysis with genomes from anaerobic and aerobic microorganisms with the aim of identifying proteins specific to the anaerobic way of life. A total of 33 COGs were identified, five of which correspond to proteins of unknown function. We focused our study on TM0486 from Thermotoga maritima, which belongs to one of these COGs of unknown function, namely COG0011. The crystal structure of the protein was determined at 2 A resolution. The structure adopts a beta alpha beta beta alpha beta ferredoxin-like fold and assembles as a homotetramer. The structure also revealed the presence of a pocket in each monomer that bound an unidentified ligand. NMR and calorimetry revealed that TM0486 specifically bound thiamin with a K(d) of 1.58 microM, but not hydroxymethyl pyrimidine (HMP), which has been implicated as a potential ligand. We demonstrated that the TM0486 gene belongs to the same multicistronic unit as TM0483, TM0484 and TM0485. Although these three genes have been assigned to the transport of HMP, with TM0484 being the periplasmic thiamin/HMP-binding protein and TM0485 and TM0483 the transmembrane and the ATPase components, respectively, our results led us to conclude that this operon encodes an ABC transporter dedicated to thiamin, with TM0486 transporting charged thiamin in the cytoplasm. Given that this transcriptional unit was up-regulated when T. maritima was exposed to oxidative conditions, we propose that, by chelating cytoplasmic thiamin, TM0486 and, by extension, proteins belonging to COG0011 are involved in the response mechanism to stress that could arise during aerobic conditions.

  4. Simultaneous Hydrogen and Methane Production Through Multi-Phase Anaerobic Digestion of Paperboard Mill Wastewater Under Different Operating Conditions.

    PubMed

    Farghaly, Ahmed; Tawfik, Ahmed

    2017-01-01

    Multi-phase anaerobic reactor for H2 and CH4 production from paperboard mill wastewater was studied. The reactor was operated at hydraulic retention times (HRTs) of 12, 18, 24, and 36 h, and organic loading rates (OLRs) of 2.2, 1.5, 1.1, and 0.75 kg chemical oxygen demand (COD)/m(3) day, respectively. HRT of 12 h and OLR of 2.2 kg COD/m(3) day provided maximum hydrogen yield of 42.76 ± 14.5 ml/g CODremoved and volumetric substrate uptake rate (-rS) of 16.51 ± 4.43 mg COD/L h. This corresponded to the highest soluble COD/total COD (SCOD/TCOD) ratio of 56.25 ± 3.3 % and the maximum volatile fatty acid (VFA) yield (YVFA) of 0.21 ± 0.03 g VFA/g COD, confirming that H2 was mainly produced through SCOD conversion. The highest methane yield (18.78 ± 3.8 ml/g CODremoved) and -rS of 21.74 ± 1.34 mgCOD/L h were achieved at an HRT of 36 h and OLR of 0.75 kg COD/m(3) day. The maximum hydrogen production rate (HPR) and methane production rate (MPR) were achieved at carbon to nitrogen (C/N) ratio of 47.9 and 14.3, respectively. This implies the important effect of C/N ratio on the distinction between the dominant microorganism bioactivities responsible for H2 and CH4 production.

  5. Persistence and cell culturability of biocontrol strain Pseudomonas fluorescens CHA0 under plough pan conditions in soil and influence of the anaerobic regulator gene anr.

    PubMed

    Mascher, Fabio; Schnider-Keel, Ursula; Haas, Dieter; Défago, Geneviève; Moënne-Loccoz, Yvan

    2003-02-01

    Certain fluorescent pseudomonads can protect plants from soil-borne pathogens, and it is important to understand how these biocontrol agents survive in soil. The persistence of the biocontrol strain Pseudomonas fluorescens CHA0-Rif under plough pan conditions was assessed in non-sterile soil microcosms by counting total cells (immunofluorescence microscopy), intact cells (BacLight membrane permeability test), viable cells (Kogure's substrate-responsiveness test) and culturable cells (colony counts on selective plates) of the inoculant. Viable but non-culturable cells of CHA0-Rif (106 cells g-1 soil) were found in flooded microcosms amended with fermentable organic matter, in which the soil redox potential was low (plough pan conditions), in agreement with previous observations of plough pan samples from a field inoculated with CHA0-Rif. However, viable but non-culturable cells were not found in unamended flooded, amended unflooded or unamended unflooded (i.e. control) microcosms, suggesting that such cells resulted from exposure of CHA0-Rif to a combination of low redox potential and oxygen limitation in soil. CHA0-Rif is strictly aerobic. Its anaerobic regulator ANR is activated by low oxygen concentrations and it controls production of the biocontrol metabolite hydrogen cyanide under microaerophilic conditions. Under plough pan conditions, an anr-deficient mutant of CHA0-Rif and its complemented derivative displayed the same persistence pattern as CHA0-Rif, indicating that anr was not implicated in the formation of viable but non-culturable cells of this strain at the plough pan.

  6. Effect of feeding strategy on the stability of anaerobic sequencing batch reactor responses to organic loading conditions.

    PubMed

    Cheong, Dae-Yeol; Hansen, Conly L

    2008-07-01

    The goal of this study was to examine the effect of feeding strategy on the capability for treatment and the stability of an anaerobic sequencing batch reactor (ASBR) under increasing organic loading. The lab-scale ASBR systems were operated at 35 degrees C using synthetic organic wastewater under both batch and fed-batch operational modes with different feed to cycle time (F:C) ratios. Experimental studies were conducted over a wide range of volumetric organic loading rates (VOLRs) (1.524 g COD/l/d) by varying the hydraulic retention time (HRT) (1.25, 2.5, and 5d) and the feed wastewater's COD (3750-30,000 mg/l). With an F:C ratio greater than or equal to 0.42, the fed-batch mode operation showed higher system efficiency in COD removal, volumetric methane production rate (VMPR), and specific methane production rate (SMPR) as compared to those in the batch mode with identical VOLR and HRT. In the fed-batch mode, the COD removals reached 86-95% with VOLR up to 12 g COD/l/d. The maximums for VMPR of 3.17 l CH4/l/d and for SMPR of 1.63 g CH4-COD/g VSS/d were achieved with a VOLR of 12 g COD/l/d at HRTs of 2.5 and 1.25 d, respectively. The fed-batch operation presented a lower concentration of volatile fatty acids (VFAs) than those in the batch operation. A lower concentration of VFAs confirmed the stability and efficiency of the fed-batch mode operation. The specific methanogenic activity (SMA) analysis showed that the VFA-degrading activity of the biomass in the fed-batch mode was higher for acetate and butyrate, and lower for propionate. Determined biomass yield and bacterial decay coefficients in the fed-batch operational mode were 0.05 g VSS/g COD rem and 0.001 d(-1), respectively.

  7. Constitutive expression of Campylobacter jejuni truncated hemoglobin CtrHb improves the growth of Escherichia coli cell under aerobic and anaerobic conditions.

    PubMed

    Yang, Jiang-Ke; Xiong, Wei; Xu, Li; Li, Jia; Zhao, Xiu-Ju

    2015-01-01

    Bacteria hemoglobin could bind to the oxygen, transfer it from the intracellular microenvironment to the respiration process and sustain the energy for the metabolism and reproduction of cells. Heterologous expression of bacteria hemoglobin gene could improve the capacity of the host on oxygen-capturing and allow it to grow even under microaerophilic condition. To develop a system based on hemoglobin to help bacteria cells overcome the oxygen shortage in fermentation, in this study, Campylobacter jejuni truncated hemoglobin (CtrHb) gene was synthesized and expressed under the control of constitutive expression promoters P2 and P(SPO1-II) in Escherichia coli. As showed by the growth curves of the two recombinants P2-CtrHb and P(SPO1-II)-CtrHb, constitutive expression of CtrHb improved cell growth under aerobic shaking-flasks, anaerobic capped-bottles and bioreactor conditions. According to the NMR analysis, this improvement might come from the expression of hemoglobin which could boost the metabolism of cells by supplying more oxygen to the respiratory chain processes. Through semi-quantitative RT-PCR and CO differential spectrum assays, we further discussed the connection between the growth patterns of the recombinants, the expression level of CtrHb and oxygen binding capacity of CtrHb in cells. Based on the growth patterns of these recombinants in bioreactor, a possible choice on different type of recombinants under specific fermentation conditions was also suggested in this study.

  8. 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.

  9. 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.

  10. Effects of the operational conditions on the production of 1,3-propanediol derived from glycerol in anaerobic granular sludge reactors.

    PubMed

    Nakazawa, Mitsue M; Florencio, Lourdinha; Kato, Mario T; Gavazza, Savia; Sanz, Jose L

    2017-02-01

    The aim of this study has been to produce 1,3-propanediol (1,3-PDO) from glycerol (gly) fermentation by means of a microbial mixed culture (granular sludge), as well as to establish the operational conditions of two up-flow anaerobic sludge blanket (UASB) reactors in order to achieve a maximum 1,3-PDO yield. The UASB reactors with initial pH values set at 6.8 and 5.5 were operated at 30 °C during 165 days. Thirteen variables were previously screened by a Plackett-Burman (PB) design; results showed that yeast extract, MgSO4 and methanogenesis inhibition (by heat shock) showed a positive effect, whereas high glycerol concentration, tryptone and CaCl2 showed a negative impact on the 1,3-PDO produced by glycerol degradation. Following four experimental periods, the highest average yield of 0.43 mol 1,3-PDO mol(-1) gly was achieved when sodium bicarbonate was added to the reactors. Propionate and acetate were also produced and a high microorganism diversity was detected; however, the restrictive operational conditions of the reactors led to the death of the methanogenic archaea. Nevertheless, the continuous production of 1,3-PDO from glycerol within UASB reactors inoculated with granular sludge can be considered highly feasible.

  11. Biogas production from co-digestion of corn stover and chicken manure under anaerobic wet, hemi-solid, and solid state conditions.

    PubMed

    Li, Yeqing; Zhang, Ruihong; Chen, Chang; Liu, Guangqing; He, Yanfeng; Liu, Xiaoying

    2013-12-01

    Corn stover (CS) and chicken manure (CM) are ubiquitous agricultural wastes at low cost and have the potential to achieve a nutrient-balance when mixed together to produce biomethane via anaerobic digestion (AD). The main objective of this work was to investigate methane production at different CS to CM ratios and to evaluate the process stability under wet (W-AD), hemi-solid state (HSS-AD) and solid state (SS-AD) conditions. Results showed that synergistic effects were found when mixing two substrates at CS:CM ratios of 3:1 and 1:1 (on volatile solid basis). The highest methane yield of 218.8 mL/g VS added was achieved in W-AD at CS:CM ratio of 3:1. In SS-AD, the highest volumetric methane productivity of 14.2L methane/L reactor volume was found at CS:CM of 1:1. The results of this work provide useful information to improve the efficiency and stability of co-digestion of CS and CM under different AD conditions. Copyright © 2013 Elsevier Ltd. All rights reserved.

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

    PubMed

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

    2016-03-01

    This study was performed to identify suitable conditions for the in-situ reduction of excess sludge production by intercalated digesters in recycle-activated sludge (RAS) flow. The objective was to compare and model biological sludge mass reduction and the biodegradation of endogenous residues (XP) by digestion under hypoxic, aerobic, anaerobic, and five intermittent-aeration conditions. A mathematical model based on the heterotrophic endogenous decay constant (bH) and including the biodegradation of XP was used to fit the long-term data from the digesters to identify and estimate the parameters. Both the bH constant (0.02-0.05 d(-1)) and the endogenous residue biodegradation constant (bP, 0.001-0.004 d(-1)) were determined across the different mediums. The digesters with intermittent aeration cycles of 12 h-12 h and 5 min-3 h (ON/OFF) were the fastest, compared to the aerobic reactor. The study provides a basis for rating RAS-digester volumes to avoid the accumulation of XP in aeration tanks. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. The Effects of a Sport-Specific Maximal Strength and Conditioning Training on Critical Velocity, Anaerobic Running Distance, and 5-km Race Performance.

    PubMed

    Karsten, Bettina; Stevens, Liesbeth; Colpus, Mark; Larumbe-Zabala, Eneko; Naclerio, Fernando

    2016-01-01

    To investigate the effects of a sport-specific maximal 6-wk strength and conditioning program on critical velocity (CV), anaerobic running distance (ARD), and 5-km time-trial performance (TT). 16 moderately trained recreational endurance runners were tested for CV, ARD, and TT performances on 3 separate occasions (baseline, midstudy, and poststudy). Participants were randomly allocated into a strength and conditioning group (S&C; n = 8) and a comparison endurance-training-only group (EO; n = 8). During the first phase of the study (6 wk), the S&C group performed concurrent maximal strength and endurance training, while the EO group performed endurance-only training. After the retest of all variables (midstudy), both groups subsequently, during phase 2, performed another 6 wk of endurance-only training that was followed by poststudy tests. No significant change for CV was identified in either group. The S&C group demonstrated a significant decrease for ARD values after phases 1 and 2 of the study. TT performances were significantly different in the S&C group after the intervention, with a performance improvement of 3.62%. This performance increase returned close to baseline after the 6-wk endurance-only training. Combining a 6-wk resistance-training program with endurance training significantly improves 5-km TT performance. Removing strength training results in some loss of those performance improvements.

  14. Anaerobic treatment of tequila vinasses under seasonal operating conditions: start-up, normal operation and restart-up after a long stop and starvation period.

    PubMed

    Jáuregui-Jáuregui, J A; Méndez-Acosta, H O; González-Álvarez, V; Snell-Castro, R; Alcaraz-González, V; Godon, J J

    2014-09-01

    This study examines the performance of an anaerobic fixed-film bioreactor under seasonal operating conditions prevailing in medium and small size Tequila factories: start-up, normal operation and particularly, during the restart-up after a long stop and starvation period. The proposed start-up procedure attained a stable biofilm in a rather short period (28 days) despite unbalanced COD/N/P ratio and the use of non-acclimated inoculum. The bioreactor was restarted-up after being shut down for 6 months during which the inoculum starved. Even when biofilm detachment and bioreactor clogging were detected at the very beginning of restart-up, results show that the bioreactor performed better as higher COD removal and methane yield were attained. CE-SSCP and Q-PCR analyses, conducted on the biofilm prokaryotic communities for each operating condition, confirmed that the high COD removal results after the bioreactor clogging and the severe starvation period were mainly due to the stable archaeal and resilient bacterial populations.

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

    PubMed

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

    2015-05-01

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

  16. Comparative Analysis of Performance and Microbial Characteristics Between High-Solid and Low-Solid Anaerobic Digestion of Sewage Sludge Under Mesophilic Conditions.

    PubMed

    Lu, Qin; Yi, Jing; Yang, Dianhai

    2016-01-01

    High-solid anaerobic digestion of sewage sludge achieves highly efficient volatile solid reduction, and production of volatile fatty acid (VFA) and methane compared with conventional low-solid anaerobic digestion. In this study, the potential mechanisms of the better performance in high-solid anaerobic digestion of sewage sludge were investigated by using 454 high-throughput pyrosequencing and real-time PCR to analyze the microbial characteristics in sewage sludge fermentation reactors. The results obtained by 454 high-throughput pyrosequencing revealed that the phyla Chloroflexi, Bacteroidetes, and Firmicutes were the dominant functional microorganisms in high-solid and low-solid anaerobic systems. Meanwhile, the real-time PCR assays showed that high-solid anaerobic digestion significantly increased the number of total bacteria, which enhanced the hydrolysis and acidification of sewage sludge. Further study indicated that the number of total archaea (dominated by Methanosarcina) in a high-solid anaerobic fermentation reactor was also higher than that in a low-solid reactor, resulting in higher VFA consumption and methane production. Hence, the increased key bacteria and methanogenic archaea involved in sewage sludge hydrolysis, acidification, and methanogenesis resulted in the better performance of high-solid anaerobic sewage sludge fermentation.

  17. Anaerobic Biodegradation Of Methyl tert-Butyl Ether Under Iron-Reducing Conditions In Batch And Continuous-Flow Cultures

    EPA Science Inventory

    The feasibility of biodegradation of the fuel oxygenate methyl tert-butyl ether (MTBE) under iron-reducing conditions was explored in batch and continuous-flow systems. A porous pot completely-mixed reactor was seeded with diverse cultures and operated under iron-reducing...

  18. Anaerobic Biodegradation Of Methyl tert-Butyl Ether Under Iron-Reducing Conditions In Batch And Continuous-Flow Cultures

    EPA Science Inventory

    The feasibility of biodegradation of the fuel oxygenate methyl tert-butyl ether (MTBE) under iron-reducing conditions was explored in batch and continuous-flow systems. A porous pot completely-mixed reactor was seeded with diverse cultures and operated under iron-reducing...

  19. Mitochondria from Dipodascus (Endomyces) magnusii and Yarrowia lipolytica yeasts did not undergo a Ca²⁺-dependent permeability transition even under anaerobic conditions.

    PubMed

    Trendeleva, Tat'yana; Sukhanova, Evgeniya; Ural'skaya, Ludmila; Saris, Nils-Erik; Zvyagilskaya, Renata

    2011-12-01

    In this study we used tightly-coupled mitochondria from Yarrowia lipolytica and Dipodascus (Endomyces) magnusii yeasts. The two yeast strains are good alternatives to Saccharomyces cerevisiae, being aerobes containing well structured mitochondria (thus ensuring less structural limitation to observe their appreciable swelling) and fully competent respiratory chain with three invariantly functioning energy conservation points, including Complex I, that can be involved in induction of the canonical Ca²⁺/P(i)-dependent mitochondrial permeability transition (mPTP pore) with an increased open probability when electron flux increases(Fontaine et al. J Biol Chem 273: 25734–25740, 1998; Bernardi et al. FEBS J 273:2077–2099, 2006). High amplitude swelling and collapse of the membrane potential were used as parameters for demonstrating pore opening. Previously (Kovaleva et al. J Bioenerg Biomembr 41:239–249, 2009; Kovaleva et al. Biochemistry (Moscow) 75: 297–303, 2010) we have shown that mitochondria from Y.lipolytica and D. magnusii were very resistant to the Ca²⁺overload combined with varying concentrations of P(i),palmitic acid, SH-reagents, carboxyatractyloside (an inhibitor of ADP/ATP translocator), as well as depletion of intramitochondrial adenine nucleotide pools, deenergization of mitochondria, and shifting to acidic pH values in the presence of high [P(i)]. Here we subjected yeast mitochondria to other conditions known to induce an mPTP in animal and plant mitochondria, namely to Ca²⁺ overload under hypoxic conditions (anaerobiosis). We were unable to observe Ca²⁺-induced high permeability of the inner membrane of D. magnusii and Y. lipolytica yeast mitochondria under anaerobic conditions, thus suggesting that an mPTP-like pore, if it ever occurs in yeast mitochondria, is not coupled with the Ca²⁺ uptake. The results provide the first demonstration of ATP-dependent energization of yeast mitochondria under conditions of anaerobiosis.

  20. Responses of Alnus glutinosa to anaerobic conditions--mechanisms and rate of oxygen flux into the roots.

    PubMed

    Dittert, K; Wötzel, J; Sattelmacher, B

    2006-03-01

    Upon exposure to waterlogged growing conditions two-year-old alder trees reduced total root mass. Roots were concentrated in the uppermost soil horizon, and only few coarse roots penetrated into deeper soil layers. Root porosity was only slightly affected and did not exceed 8 % in fine roots. Porosity of coarse roots was higher (27 %) but unaffected by growing conditions. The stem base area covered by lenticels increased strongly and so did the cross section diameter of the stem base. The latter showed a highly significant correlation with O (2) transport into the roots, measured by a Clark type oxygen electrode. Exposure of the lower 5 cm of the stem base, where lenticels were concentrated, to pure N (2) led to a cessation of O (2) transport, confirming that lenticels were the major site of air entry into the stem. In alder plants grown under waterlogged conditions, temperature had a pronounced effect on O (2) gas exchange of the root system. The temperature compensation point, i.e., the temperature where O (2) transport equals O (2) consumption by respiration, was 10.5 degrees C for the entire root system, when measured in a range of 0.15 - 0.20 mmol dissolved O (2) L (-1), which is typical for an open water surface equilibrated with air. O (2) net flow was inversely related to O (2) concentration in the rooting media, indicating that higher root and microbial respiration induced higher net fluxes of O (2) into the root system. With 0.04 mmol dissolved O (2) L (-1) nutrient solution, the temperature compensation point increased to 20 degrees C. Measurement of O (2) gradients in the rhizosphere of agar-embedded roots using O (2) microelectrodes showed a preference for O (2) release in the tip region of coarse roots. Increasing stem temperature over air temperature by 5 degrees C stimulated O (2) flux into the roots as suggested by the model of thermo-osmotic gas transport. However determination of stem and air temperature in a natural alder swamp in northern

  1. Anaerobic codigestion of the mechanically sorted organic fraction of a municipal solid waste with cattle manure in packed microcosms under batch conditions.

    PubMed

    Bertin, L; Todaro, D; Bettini, C; Fava, F

    2008-01-01

    Packed microcosms, consisting of 0.6 L-flask filled with tire chips (TC, a non-cost-recyclable non-biodegradable material) or ceramic cubes, were employed in the wet batch mesophilic anaerobic codigestion of a mechanically sorted organic fraction of a municipal solid waste with cattle manure. Two different waste mixtures were digested within four successive batch experiments, performed by collecting the digested waste and by refilling each microcosm with the same experimental mixture. Methane production yields related to the first experiment were comparable to those of non-packed identically developed microcosms, while they significantly grew during all the following experiences. No CH4-production lag-phase was observed since the second batch experiment. Similar results were obtained for both packing materials: however, the highest methane yields were achieved within bioreactors packed with TC in the presence of a mixture in which the volatile suspended solids (VSS) provided by the municipal waste represented the 55% of the total ones. Under such condition, a methane yield corresponding to the biochemical methane potential (BMP) calculated through a 6-month experiment with non-packed microcosms (176 ml/gVS) was attained in about 1/4 of the time. Importantly, the BMP can significantly grow up as a consequence of the approach described in this study. IWA Publishing 2008.

  2. Prokaryotic diversity and dynamics in a full-scale municipal solid waste anaerobic reactor from start-up to steady-state conditions.

    PubMed

    Cardinali-Rezende, Juliana; Colturato, Luís F D B; Colturato, Thiago D B; Chartone-Souza, Edmar; Nascimento, Andréa M A; Sanz, José L

    2012-09-01

    The prokaryotic diversity of an anaerobic reactor for the treatment of municipal solid waste was investigated over the course of 2 years with the use of 16S rDNA-targeted molecular approaches. The fermentative Bacteroidetes and Firmicutes predominated, and Proteobacteria, Actinobacteria, Tenericutes and the candidate division WWE1 were also identified. Methane production was dominated by the hydrogenotrophic Methanomicrobiales (Methanoculleus sp.) and their syntrophic association with acetate-utilizing and propionate-oxidizing bacteria. qPCR demonstrated the predominance of the hydrogenotrophic over aceticlastic Methanosarcinaceae (Methanosarcina sp. and Methanimicrococcus sp.), and Methanosaetaceae (Methanosaeta sp.) were measured in low numbers in the reactor. According to the FISH and CARD-FISH analyses, Bacteria and Archaea accounted for 85% and 15% of the cells, respectively. Different cell counts for these domains were obtained by qPCR versus FISH analyses. The use of several molecular tools increases our knowledge of the prokaryotic community dynamics from start-up to steady-state conditions in a full-scale MSW reactor. Copyright © 2012 Elsevier Ltd. All rights reserved.

  3. Optimization of wastewater feeding for single-cell protein production in an anaerobic wastewater treatment process utilizing purple non-sulfur bacteria in mixed culture condition.

    PubMed

    Honda, Ryo; Fukushi, Kensuke; Yamamoto, Kazuo

    2006-10-01

    Impacts of operation timing of feeding and withdrawal on anaerobic wastewater treatment utilizing purple non-sulfur bacteria have been investigated in mixed culture condition with acidogenic bacteria. Simulated wastewater containing glucose was treated in a laboratory-scale chemostat reactor, changing the timing of wastewater feeding and withdrawal. Rhodopseudomonas palustris, which does not utilize glucose as a substrate, was inoculated in the reactor. Rps. palustris was detected by a fluorescent in situ hybridization (FISH) technique using the specific Rpal686 probe. As a result, population ratios of Rps. palustris were over 20% through the operation. Rps. palustris could grow by utilizing metabolites of acidogenic bacteria that coexisted in the reactor. A morning feed was effective for a good growth of purple non-sulfur bacteria. A protein content of cultured bacteria was the highest when wastewater was fed in the morning. Dissolved organic carbon (DOC) removal was 94% independent of the timing control. Consequently, feeding in the morning is the optimum feed-timing control from the aspects of growth of purple non-sulfur bacteria and single-cell protein production.

  4. Growth condition and bacterial community for maximum hydrolysis of suspended organic materials in anaerobic digestion of food waste-recycling wastewater.

    PubMed

    Kim, Man Deok; Song, Minkyung; Jo, Minho; Shin, Seung Gu; Khim, Jee Hyeong; Hwang, Seokhwan

    2010-02-01

    This paper reports the effects of changing pH (5-7) and temperature (T, 40-60 degrees C) on the efficiencies of bacterial hydrolysis of suspended organic matter (SOM) in wastewater from food waste recycling (FWR) and the changes in the bacterial community responsible for this hydrolysis. Maximum hydrolysis efficiency (i.e., 50.5% reduction of volatile suspended solids) was predicted to occur at pH 5.7 and T = 44.5 degrees C. Changes in short-chain volatile organic acid profiles and in acidogenic bacterial communities were investigated under these conditions. Propionic and butyric acids concentrations increased rapidly during the first 2 days of incubation. Several band sequences consistent with Clostridium spp. were detected using denaturing gel gradient electrophoresis. Clostridium thermopalmarium and Clostridium novyi seemed to contribute to butyric acid production during the first 1.5 days of acidification of FWR wastewater, and C. thermopalmarium was a major butyric acid producer afterward. C. novyi was an important propionic acid producer. These two species appear to be important contributors to hydrolysis of SOM in the wastewater. Other acidogenic anaerobes, Aeromonas sharmana, Bacillus coagulans, and Pseudomonas plecoglossicida, were also indentified.

  5. Examination of various cell culture techniques for co-incubation of virulent Treponema pallidum (Nichols I strain) under anaerobic conditions.

    PubMed Central

    Sandok, P L; Knight, S T; Jenkin, H M

    1976-01-01

    Treponema pallidum (Nichols virulent) was incubated with and without cells in cell culture medium reduced to -275 mV Ecal, pH 7.3, under deoxygenated conditions. Five to ten percent of the treponemes attached to cells and remained motile for at least 120 h in cell-treponeme systems of co-incubation. Virulent treponemes could be detected after 120 to 144 h in the supernatant fluids of cell-treponeme co-incubation cultures and in cell-free tubes containing medium harvested from aerobically cultivated mammalian cells. Medium supplemented with ox serum ultrafiltrate, pyruvate, and sodium thioglycolate and gas mixtures containing H2 and CO2 enhanced treponemal survival. Increases in treponemal numbers were observed using dark-field microscopy but were not substantiated using the rabbit lesion test. Continuous passage of the treponeme was not achieved in vitro. PMID:789395

  6. FeS-coated sand for removal of arsenic(III) under anaerobic conditions in permeable reactive barriers

    USGS Publications Warehouse

    Han, Y.-S.; Gallegos, T.J.; Demond, A.H.; Hayes, K.F.

    2011-01-01

    Iron sulfide (as mackinawite, FeS) has shown considerable promise as a material for the removal of As(III) under anoxic conditions. However, as a nanoparticulate material, synthetic FeS is not suitable for use in conventional permeable reactive barriers (PRBs). This study developed a methodology for coating a natural silica sand to produce a material of an appropriate diameter for a PRB. Aging time, pH, rinse time, and volume ratios were varied, with a maximum coating of 4.0 mg FeS/g sand achieved using a pH 5.5 solution at a 1:4 volume ratio (sand: 2 g/L FeS suspension), three days of aging and no rinsing. Comparing the mass deposited on the sand, which had a natural iron-oxide coating, with and without chemical washing showed that the iron-oxide coating was essential to the formation of a stable FeS coating. Scanning electron microscopy images of the FeS-coated sand showed a patchwise FeS surface coating. X-ray photoelectron spectroscopy showed a partial oxidation of the Fe(II) to Fe(III) during the coating process, and some oxidation of S to polysulfides. Removal of As(III) by FeS-coated sand was 30% of that by nanoparticulate FeS at pH 5 and 7. At pH 9, the relative removal was 400%, perhaps due to the natural oxide coating of the sand or a secondary mineral phase from mackinawite oxidation. Although many studies have investigated the coating of sands with iron oxides, little prior work reports coating with iron sulfides. The results suggest that a suitable PRB material for the removal of As(III) under anoxic conditions can be produced through the deposition of a coating of FeS onto natural silica sand with an iron-oxide coating. ?? 2010 Elsevier Ltd.

  7. 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.

  8. Effect of caffeine on upper-body anaerobic performance in wrestlers in simulated competition-day conditions.

    PubMed

    Aedma, Martin; Timpmann, Saima; Ööpik, Vahur

    2013-12-01

    Peak power (PP) and mean power (MP) attained in upper body sprint performance test are considered important factors for competitive success in wrestling. This study aimed to determine whether acute caffeine ingestion would better maintain PP and MP across a simulated competition day in wrestling. In a double-blind, counterbalanced, crossover study, 14 trained wrestlers ingested either placebo or 5 mg/kg caffeine and completed four 6-min upper body intermittent sprint performance tests with 30-min recovery periods between consecutive tests. PP and MP were recorded during and blood lactate concentration was measured before and after each test. Ratings of perceived fatigue (RPF) and exertion (RPE) were recorded before and after each test, respectively. Heart rate (HR) was monitored across the whole testing period. Mean power decreased across four tests in both trials (p < .05), but the reduction in PP (from 277.2 ± 34.6 W to 257.3 ± 45.1 W; p < .05) only occurred in caffeine trial. Both pretest blood lactate concentration and HR were higher in caffeine than in placebo trial (p < .05) in the third and fourth tests. No between-trial differences occurred in RPF or RPE. Under simulated competition day conditions mimicking four consecutive wrestling matches, acute caffeine ingestion has a partially detrimental effect on upper body intermittent sprint performance in trained wrestlers. Elevated HR and blood lactate levels observed between tests after caffeine ingestion suggest that caffeine may impair recovery between consecutive maximal efforts.

  9. Global warming potential of material fractions occurring in source-separated organic household waste treated by anaerobic digestion or incineration under different framework conditions.

    PubMed

    Naroznova, Irina; Møller, Jacob; Scheutz, Charlotte

    2016-12-01

    This study compared the environmental profiles of anaerobic digestion (AD) and incineration, in relation to global warming potential (GWP), for treating individual material fractions that may occur in source-separated organic household waste (SSOHW). Different framework conditions representative for the European Union member countries were considered. For AD, biogas utilisation with a biogas engine was considered and two potential situations investigated - biogas combustion with (1) combined heat and power production (CHP) and (2) electricity production only. For incineration, four technology options currently available in Europe were covered: (1) an average incinerator with CHP production, (2) an average incinerator with mainly electricity production, (3) an average incinerator with mainly heat production and (4) a state-of-the art incinerator with CHP working at high energy recovery efficiencies. The study was performed using a life cycle assessment in its consequential approach. Furthermore, the role of waste-sorting guidelines (defined by the material fractions allowed for SSOHW) in relation to GWP of treating overall SSOHW with AD was investigated. A case-study of treating 1tonne of SSOHW under framework conditions in Denmark was conducted. Under the given assumptions, vegetable food waste was the only material fraction which was always better for AD compared to incineration. For animal food waste, kitchen tissue, vegetation waste and dirty paper, AD utilisation was better unless it was compared to a highly efficient incinerator. Material fractions such as moulded fibres and dirty cardboard were attractive for AD, albeit only when AD with CHP and incineration with mainly heat production were compared. Animal straw, in contrast, was always better to incinerate. Considering the total amounts of individual material fractions in waste generated within households in Denmark, food waste (both animal and vegetable derived) and kitchen tissue are the main material

  10. 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.

  11. Cosubstrate independent mineralization of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) by a Desulfovibrio species under anaerobic conditions.

    PubMed

    Arnett, Clint M; Adrian, Neal R

    2009-02-01

    Past handling practices associated with the manufacturing and processing of the high explosive hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) has resulted in extensive environmental contamination. In-situ biodegradation is a promising technology for remediating RDX contaminated sites but often relies on the addition of a cosubstrate. A sulfate-reducing bacterium isolated from an RDX-degrading enrichment culture was studied for its ability to grow on RDX as a sole source of carbon and nitrogen and for its ability to mineralize RDX in the absence of a cosubstrate. The results showed the isolate degraded 140 muM RDX in 63 days when grown on RDX as a carbon source. Biomass within the carbon limited culture increased 9-fold compared to the RDX unamended controls. When the isolate was incubated with RDX as sole source of nitrogen it degraded 160 muM RDX in 41 days and exhibited a 4-fold increase in biomass compared to RDX unamended controls. Radiolabeled studies under carbon limiting conditions with (14)C-hexahydro-1,3,5-trinitro-1,3,5-triazine confirmed mineralization of the cyclic nitramine. After 60 days incubation 26% of the radiolabel was recovered as (14)CO(2), while in the control bottles less than 1% of the radiolabel was recovered as (14)CO(2). Additionally, approximately 2% of the radiolabeled carbon was found to be associated with the biomass. The 16S rDNA gene was sequenced and identified the isolate as a novel species of Desulfovibrio, having a 95.1% sequence similarity to Desulfovibrio desulfuricans. This is the first known anaerobic bacterium capable of mineralizing RDX when using it as a carbon and energy source for growth.

  12. Quantification of the inert chemical oxygen demand of raw wastewater and evaluation of soluble microbial product production in demo-scale upflow anaerobic sludge blanket reactors under different operational conditions.

    PubMed

    Aquino, Sergio F; Gloria, Roberto M; Silva, Silvana Q; Chernicharo, Carlos A L

    2009-06-01

    This paper investigates the production of soluble microbial products (SMPs) in demonstration-scale upflow anaerobic sludge blanket reactors operated under different conditions and fed with raw wastewater. The results showed that 9.2 +/- 1.3% of the influent soluble chemical oxygen demand (COD) could be considered inert to anaerobic treatment and that the amount of COD produced by biomass varied from 30 to 70 mg x L(-1), accounting for 45 to 63% of the soluble effluent COD. The accumulation of SMP appeared to be dependent on the hydraulic retention time (HRT) applied to the reactors, with a larger accumulation of SMP observed at the lowest HRT (5 hours); this may have been due to stress conditions caused by high upflow velocity (1.1 m x h(-1)). In terms of residual COD characterization, ultrafiltration results showed that higher amounts of high molecular weight compounds were found when HRT was the lowest (5 hours), and that the molecular weight distribution depended on the operational condition of the reactors. Biodegradability tests showed that the low and high molecular weight SMPs were only partially degraded anaerobically (10 to 60%) and that the high molecular weight SMPs were difficult to degrade aerobically.

  13. 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

  14. Effect of anaerobic soil disinfestation on the bacterial community and key soilborne phytopathogenic agents under walnut tree-crop nursery conditions

    USDA-ARS?s Scientific Manuscript database

    Background and Aims: Anaerobic Soil Disinfestation (ASD) is a chemical-independent approach to manage soilborne phytopathogens. While it has been demonstrated that ASD can suppress phytopathogens in vegetable cropping systems, it has not been examined for control of tree-crop diseases. We examined t...

  15. 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

  16. 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.

  17. The curing agent sodium nitrite, used in the production of fermented sausages, is less inhibiting to the bacteriocin-producing meat starter culture Lactobacillus curvatus LTH 1174 under anaerobic conditions.

    PubMed

    Verluyten, Jurgen; Messens, Winy; De Vuyst, Luc

    2003-07-01

    Curvacin A is a listericidal bacteriocin produced by Lactobacillus curvatus LTH 1174, a strain isolated from fermented sausage. The response of this strain to an added curing agent (sodium nitrite) in terms of cell growth and bacteriocin production was investigated in vitro by laboratory fermentations with modified MRS broth. The strain was highly sensitive to nitrite; even a concentration of 10 ppm of curing agent inhibited its growth and both volumetric and specific bacteriocin production. A meat simulation medium containing 5 ppm of sodium nitrite was tested to investigate the influence of the gas phase on the growth and bacteriocin production of L. curvatus LTH 1174. Aerating the culture during growth had no effect on biomass formation, but the oxidative stress caused a higher level of specific bacteriocin production and led to a metabolic shift toward acetic acid production. Anaerobic conditions, on the other hand, led to an increased biomass concentration and less growth inhibition. Also, higher maximum volumetric bacteriocin activities and a higher level of specific bacteriocin production were obtained in the presence of sodium nitrite than in fermentations under aerobic conditions or standard conditions of air supply. These results indicate that the inhibitory effect of the curing agent is at least partially masked under anaerobic conditions.

  18. 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).

  19. Use of 13C Labeled Carbon Tetrachloride to Demonstrate the Transformation to Carbon Dioxide under Anaerobic Conditions in a Continuous Flow Column

    NASA Astrophysics Data System (ADS)

    Semprini, L.; Azizian, M.

    2012-12-01

    The demonstration of transformation of chlorinated aliphatic compounds (CAHs) in the subsurface is a challenge, especially when the products are carbon dioxide (CO2) and chloride ion. The groundwater contaminant carbon tetrachloride (CT) is of particular interest since a broad range of transformation products can be potentially formed under anaerobic conditions. The ability to demonstrate the transformation of CT to CO2 as a non toxic endproduct, is also of great interest. Results will be presented from a continuous flow column study where 13C labeled CT was used to demonstrate its transformation to CO2. The column was packed with a quartz sand and bioaugmented the Evanite Culture (EV) that is capable of transforming tetrachloroethene (PCE) to ethene. The column was continously fed a synthetic groundwater that was amended with PCE (0.10 mM) and either formate (1.5 mM) or lactate (1.1 mM), which ferments to produce hydrogen (H2) as the ultimate electron donor. Earlier CT transformation studies with the column, in the absence of sulfate reduction, and with formate added as a donor found CT (0.015 mM) was over 98% transformed with about 20% converted to chloroform (CF) (0.003 mM) and with a transient detection of chloromethane (CM). Methane and carbon disulfide, as potential products, were not detected. Neither CT nor CF inhibited the reductive dehalogenation of PCE to ethene. A series of transient studies conducted after these initial CT transformation tests, but in the absence of CT, showed formate remained an effective substrate for maintaining sulfate reduction and PCE transformation. Lactate, which was effectively fermented prior to CT addition, was not effectively fermented, with propionate accumulating as a fermentation product. When lactate was added, PCE was mainly transformed to cis-dichloroethene (cis-DCE) and VC, and sulfate reduction did not occur. In order to restore effective lactate fermentation the column was then bioaugmented with an EV culture that

  20. 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.

  1. Aerobic and anaerobic cellulase production by Cellulomonas uda.

    PubMed

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

    2016-10-01

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

  2. Anaerobic digestion of horse dung mixed with different bedding materials in an upflow solid-state (UASS) reactor at mesophilic conditions.

    PubMed

    Böske, Janina; Wirth, Benjamin; Garlipp, Felix; Mumme, Jan; Van den Weghe, Herman

    2014-04-01

    Aim of this study was to investigate the use of upflow anaerobic solid-state (UASS) digestion for treating horse manure. Biochemical methane potential (BMP) tests conducted for varying mixtures of dung (hay and silage feed) and bedding material (wheat straw, flax, hemp, wood chips) showed that straw mixed with hay horse dung has the highest potential of [Formula: see text] . Continuous mesophilic digestion was conducted for 238 days using a single-stage UASS reactor (27 L) and a two-stage UASS system with an anaerobic filter (AF, 21 L). Increasing the organic loading rate (OLR) from 2.5 to 4.5 g vs L(-1)d(-1) enhanced the methane rate of the single-stage reactor from 0.262 to 0.391 LL(-1)d(-1) while the methane yield declined from 104.8 to 86.9 L kg vs(-1). The two-stage system showed similar yields. Thus, for solid-state digestion of horse manure a single-stage UASS reactor appears sufficient.

  3. 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.

  4. 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

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

    PubMed Central

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

    2016-01-01

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

  6. 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

  7. [Effect of carbon substrate concentration on N2, N2O, NO, CO2, and CH4 emissions from a paddy soil in anaerobic condition].

    PubMed

    Chen, Nuo; Liao, Ting-ting; Wang, Rui; Zheng, Xun-hua; Hu, Rong-gui; Butterbach-Bahl, Klaus

    2014-09-01

    Understanding the effects of carbon and nitrogen substrates concentrations on the emissions of denitrification gases including nitrogen (N2) , nitrous oxide (N2O) and nitric oxide (NO), carbon dioxide (CO2) and methane (CH4) from anaerobic paddy soils is believed to be helpful for development of greenhouse gas mitigation strategies. Moreover, understanding the quantitative dependence of denitrification products compositions on carbon substrate concentration could provide some key parameters or parameterization scheme for developing process-oriented model(s) of nitrogen transformation. Using a silt loam soil collected from a paddy field, we investigated the influence of carbon substrate concentration on the emissions of the denitrification gases, CO2 and CH4 from anaerobically incubated soils by setting two treatments: control (CK) with initial soil nitrate and dissolved organic carbon (DOC) concentrations of ~ 50 mg.kg-1 and -28 mg kg-1 , respectively; and DOC added (C + ) with initial soil nitrate and DOC concentrations of ~50 mg.kg-1 and ~300 mg.kg-1 , respectively. The emissions of denitrification gases, CO2 and CH4, as well as concentrations of carbon and nitrogen substrates for each treatment were dynamically measured, using the gas-flow-soil-core technique and a paralleling substrate monitoring system. The results showed that CH4 emission was not observed in CK treatment while observed in C treatment. Aggregate emission of greenhouse gases for C + treatment was significantly higher comparing with the CK treatment (P <0. 01). The mass fractions of NO, N20 and N2 emissions in total nitrogen gases emissions were approximately 9% , 35% and 56% for CK treatment, respectively; and approximately 31% , 50% and 19% for C+ treatment, respectively, with significant differences between these two treatments (P < 0.01). The results indicated that carbon substrate concentrations can significantly change the composition of nitrogen gas emissions. The results also implicated

  8. 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

  9. 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.

  10. Sub-critical filtration conditions of commercial hollow-fibre membranes in a submerged anaerobic MBR (HF-SAnMBR) system: the effect of gas sparging intensity.

    PubMed

    Robles, A; Ruano, M V; García-Usach, F; Ferrer, J

    2012-06-01

    A submerged anaerobic MBR demonstration plant with two commercial hollow-fibre ultrafiltration systems (PURON®, Koch Membrane Systems, PUR-PSH31) was operated using municipal wastewater at high levels of mixed liquor total solids (MLTS) (above 22 g L(-1)). A modified flux-step method was applied to assess the critical flux (J(C)) at different gas sparging intensities. The results showed a linear dependency between J(C) and the specific gas demand per unit of membrane area (SGD(m)). J(C) ranged from 12 to 19 LMH at SGD(m) values of between 0.17 and 0.5 Nm(3) h(-1) m(-2), which are quite low in comparison to aerobic MBR. Long-term trials showed that the membranes operated steadily at fluxes close to the estimated J(C), which validates the J(C) obtained by this method. After operating the membrane for almost 2 years at sub-critical levels, no irreversible fouling problems were detected, and therefore, no chemical cleaning was conducted.

  11. Enhancement in hydrogen production by thermophilic anaerobic co-digestion of organic fraction of municipal solid waste and sewage sludge--optimization of treatment conditions.

    PubMed

    Tyagi, Vinay Kumar; Angériz Campoy, Rubén; Álvarez-Gallego, C J; Romero García, L I

    2014-07-01

    Batch dry-thermophilic anaerobic co-digestion (55°C) of organic fraction of municipal solid waste (OFMSW) and sewage sludge (SS) for hydrogen production was studied under several sludge combinations (primary sludge, PS; waste activated sludge, WAS; and mixed sludge, MS), TS concentrations (10-25%) and mixing ratios of OFMSW and SS (1:1, 2.5:1, 5:1, 10:1). The co-digestion of OFMSW and SS showed a 70% improvement in hydrogen production rate over the OFMSW fermentation only. The co-digestion of OFMSW with MS showed 47% and 115% higher hydrogen production potential as compared with OFMSW+PS and OFMSW+WAS, respectively. The maximum hydrogen yield of 51 mL H2/g VS consumed was observed at TS concentration of 20% and OFMSW to MS mixing ratio of 5:1, respectively. The acetic and butyric acids were the main acids in VFAs evolution; however, the higher butyric acid evolution indicated that the H2 fermentation was butyrate type fermentation.

  12. An Effective Method to Detect Volatile Intermediates Generated in the Bioconversion of Coal to Methane by Gas Chromatography-Mass Spectrometry after In-Situ Extraction Using Headspace Solid-Phase Micro-Extraction under Strict Anaerobic Conditions.

    PubMed

    Liu, Jianmin; Wang, Baoyu; Tai, Chao; Wu, Li; Zhao, Han; Guan, Jiadong; Chen, Linyong

    2016-01-01

    Bioconversion of coal to methane has gained increased attention in recent decades because of its economic and environmental advantages. However, the mechanism of this process is difficult to study in depth, partly because of difficulties associated with the analysis of intermediates generated in coal bioconversion. In this investigation, we report on an effective method to analyze volatile intermediates generated in the bioconversion of coal under strict anaerobic conditions. We conduct in-situ extraction of intermediates using headspace solid-phase micro-extraction followed by detection by gas chromatography-mass spectrometry. Bioconversion simulation equipment was modified and combined with a solid-phase micro-extraction device. In-situ extraction could be achieved by using the combined units, to avoid a breakdown in anaerobic conditions and to maintain the experiment continuity. More than 30 intermediates were identified qualitatively in the conversion process, and the variation in trends of some typical intermediates has been discussed. Volatile organic acids (C2-C7) were chosen for a quantitative study of the intermediates because of their importance during coal bioconversion to methane. Fiber coating, extraction time, and solution acidity were optimized in the solid-phase micro-extraction procedure. The pressure was enhanced during the bioconversion process to investigate the influence of headspace pressure on analyte extraction. The detection limits of the method ranged from 0.0006 to 0.02 mmol/L for the volatile organic acids and the relative standard deviations were between 4.6% and 11.5%. The volatile organic acids (C2-C7) generated in the bioconversion process were 0.01-1.15 mmol/L with a recovery range from 80% to 105%. The developed method is useful for further in-depth research on the bioconversion of coal to methane.

  13. An Effective Method to Detect Volatile Intermediates Generated in the Bioconversion of Coal to Methane by Gas Chromatography-Mass Spectrometry after In-Situ Extraction Using Headspace Solid-Phase Micro-Extraction under Strict Anaerobic Conditions

    PubMed Central

    Liu, Jianmin; Wang, Baoyu; Tai, Chao; Wu, Li; Zhao, Han; Guan, Jiadong; Chen, Linyong

    2016-01-01

    Bioconversion of coal to methane has gained increased attention in recent decades because of its economic and environmental advantages. However, the mechanism of this process is difficult to study in depth, partly because of difficulties associated with the analysis of intermediates generated in coal bioconversion. In this investigation, we report on an effective method to analyze volatile intermediates generated in the bioconversion of coal under strict anaerobic conditions. We conduct in-situ extraction of intermediates using headspace solid-phase micro-extraction followed by detection by gas chromatography-mass spectrometry. Bioconversion simulation equipment was modified and combined with a solid-phase micro-extraction device. In-situ extraction could be achieved by using the combined units, to avoid a breakdown in anaerobic conditions and to maintain the experiment continuity. More than 30 intermediates were identified qualitatively in the conversion process, and the variation in trends of some typical intermediates has been discussed. Volatile organic acids (C2–C7) were chosen for a quantitative study of the intermediates because of their importance during coal bioconversion to methane. Fiber coating, extraction time, and solution acidity were optimized in the solid-phase micro-extraction procedure. The pressure was enhanced during the bioconversion process to investigate the influence of headspace pressure on analyte extraction. The detection limits of the method ranged from 0.0006 to 0.02 mmol/L for the volatile organic acids and the relative standard deviations were between 4.6% and 11.5%. The volatile organic acids (C2–C7) generated in the bioconversion process were 0.01–1.15 mmol/L with a recovery range from 80% to 105%. The developed method is useful for further in-depth research on the bioconversion of coal to methane. PMID:27695055

  14. In situ detection of anaerobic alkane metabolites in subsurface environments

    PubMed Central

    Agrawal, Akhil; Gieg, Lisa M.

    2013-01-01

    Alkanes comprise a substantial fraction of crude oil and refined fuels. As such, they are prevalent within deep subsurface fossil fuel deposits and in shallow subsurface environments such as aquifers that are contaminated with hydrocarbons. These environments are typically anaerobic, and host diverse microbial communities that can potentially use alkanes as substrates. Anaerobic alkane biodegradation has been reported to occur under nitrate-reducing, sulfate-reducing, and methanogenic conditions. Elucidating the pathways of anaerobic alkane metabolism has been of interest in order to understand how microbes can be used to remediate contaminated sites. Alkane activation primarily occurs by addition to fumarate, yielding alkylsuccinates, unique anaerobic metabolites that can be used to indicate in situ anaerobic alkane metabolism. These metabolites have been detected in hydrocarbon-contaminated shallow aquifers, offering strong evidence for intrinsic anaerobic bioremediation. Recently, studies have also revealed that alkylsuccinates are present in oil and coal seam production waters, indicating that anaerobic microbial communities can utilize alkanes in these deeper subsurface environments. In many crude oil reservoirs, the in situ anaerobic metabolism of hydrocarbons such as alkanes may be contributing to modern-day detrimental effects such as oilfield souring, or may lead to more beneficial technologies such as enhanced energy recovery from mature oilfields. In this review, we briefly describe the key metabolic pathways for anaerobic alkane (including n-alkanes, isoalkanes, and cyclic alkanes) metabolism and highlight several field reports wherein alkylsuccinates have provided evidence for anaerobic in situ alkane metabolism in shallow and deep subsurface environments. PMID:23761789

  15. In situ detection of anaerobic alkane metabolites in subsurface environments.

    PubMed

    Agrawal, Akhil; Gieg, Lisa M

    2013-01-01

    Alkanes comprise a substantial fraction of crude oil and refined fuels. As such, they are prevalent within deep subsurface fossil fuel deposits and in shallow subsurface environments such as aquifers that are contaminated with hydrocarbons. These environments are typically anaerobic, and host diverse microbial communities that can potentially use alkanes as substrates. Anaerobic alkane biodegradation has been reported to occur under nitrate-reducing, sulfate-reducing, and methanogenic conditions. Elucidating the pathways of anaerobic alkane metabolism has been of interest in order to understand how microbes can be used to remediate contaminated sites. Alkane activation primarily occurs by addition to fumarate, yielding alkylsuccinates, unique anaerobic metabolites that can be used to indicate in situ anaerobic alkane metabolism. These metabolites have been detected in hydrocarbon-contaminated shallow aquifers, offering strong evidence for intrinsic anaerobic bioremediation. Recently, studies have also revealed that alkylsuccinates are present in oil and coal seam production waters, indicating that anaerobic microbial communities can utilize alkanes in these deeper subsurface environments. In many crude oil reservoirs, the in situ anaerobic metabolism of hydrocarbons such as alkanes may be contributing to modern-day detrimental effects such as oilfield souring, or may lead to more beneficial technologies such as enhanced energy recovery from mature oilfields. In this review, we briefly describe the key metabolic pathways for anaerobic alkane (including n-alkanes, isoalkanes, and cyclic alkanes) metabolism and highlight several field reports wherein alkylsuccinates have provided evidence for anaerobic in situ alkane metabolism in shallow and deep subsurface environments.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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...

  2. 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...

  3. Anaerobic Metabolism and Bioremediation of Explosives-Contaminated Soil

    NASA Astrophysics Data System (ADS)

    Boopathy, Raj

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

  4. ANAEROBIC BIOLOGICAL TREATMENT OF PRODUCED WATER

    SciTech Connect

    John R. Gallagher

    2001-07-31

    reactor. Batch tests were conducted to examine naphthenic acid biodegradability under several conditions. The conditions used were seed from the anaerobic reactor, wetland sediments under aerobic and anaerobic conditions, and a sterile control. The naphthenic acid was from a commercial source isolated from Gulf Coast petroleum as was dosed at 2 mg/mL. The incubations were for 30 days at 30 C. The results showed that the naphthenic acids were not biodegraded under anaerobic conditions, but were degraded under aerobic conditions. Despite poor performance of the anaerobic reactor, it remains likely that anaerobic treatment of acetate, toluene, and, potentially, other produced-water components is feasible.

  5. 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

  6. [Characteristics of N2, N2O, NO, CO2 and CH4 Emissions in Anaerobic Condition from Sandy Loam Paddy Soil].

    PubMed

    Cao, Na; Wang, Rui; Liao, Ting-ting; Chen, Nuo; Zheng, Xun-hua; Yao, Zhi-sheng; Zhang, Hai; Butterbach-Bahl, Klaus

    2015-09-01

    Understanding the characteristics of the production of nitrogen gases (N2, N2O and NO), CO2 and CH4 in anaerobic paddy soils is not only a prerequisite for an improved mechanistic understanding of key microbial processes involved in the production of atmospheric greenhouse gases (GHG), but might also provide the basis for designing greenhouse gas mitigation strategies. Moreover, quantifying the composition fractions of denitrification gaseous products is of key importance for improving parameterization schemes of microbial processes in process-oriented models which are increasingly used for assessing soil GHG emissions at site and national scales. In our experiments we investigated two sandy loam soils from two paddy fields. The initial concentrations of soil nitrate and dissolved organic carbon (DOC) were set at approximately 50 mg.kg-1 and mg.kg-1, respectively, by adding a mixture solution of KNO3 and glucose. The emissions of N2, N2O NO, CO2 and CH4, as well as concentrations of carbon and nitrogen substrates for each soil sample were measured simultaneously, using a gas-flow-soil-core technique and a paralleling substrate monitoring system. The results showed that the accumulative emissions of N2, N2O and NO of the two soil samples for the entire incubation period were 6 - 8, 20, and 15 - 18 mg.kg-1, respectively. By measuring the cumulative emissions of denitrification gases (N, = N2 + N2O + NO) we were able to explain 95% to 98% of observed changes in s1ifr nilrate concentrations. The mass fractions of N2, N2O and NO emissions to Nt were approximately 15% -19%, 47% -49%, and 34% -36%, respectively. Thus, in our experiments N2O and NO were the main products of denitrification for the entire incubation period. However, as the temporal courses of hourly or daily production of the denitrification gases showed, NO production dominated and peaked firstly, and then N2O, before finally N2 became the dominant product. Our results show the high temporal dynamic of

  7. 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

  8. Anaerobic soil disinfestation and soil borne pest management

    USDA-ARS?s Scientific Manuscript database

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

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

    PubMed

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

    2014-12-01

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

  10. Kinetic, dynamic, and pathway studies of glycerol metabolism by Klebsiella pneumoniae in anaerobic continuous culture: II. Analysis of metabolic rates and pathways under oscillation and steady-state conditions.

    PubMed

    Zeng, A P; Menzel, K; Deckwer, W D

    1996-12-05

    The oscillation phenomena reported in the preceding article for the anaerobic continuous fermentation of glycerol by Klebsiella pneumoniae are analyzed in terms of metabolic fluxes (metabolic rates and yields) and stoichiometry of pathways. Significant oscillations in the fluxes of CO(2), H(2), formic acid, ethanol, and reducing equivalents are observed which show obvious relationships to each other. Changes in the consumption or production rates of glycerol, acetic acid, 1,3-propanediol, and ATP are irregular and have relatively small amplitudes compared with their absolute values. By comparing the metabolic fluxes under oscillation and steady state that have nearly the same environmental conditions it could be shown that pyruvate metabolism is the main step affected under oscillation conditions. The specific formation rates of all the products originating from pyruvate metabolism (CO(2), H(2), formic acid, ethanol, acetic acid, lactic acid, and 2,3-butanediol) show significant differences under conditions of oscillation and steady state. In contrast, the specific rates of substrate uptake, ATP generation, and formation of products deriving either directly from glycerol (1,3-propanediol) or from the upstream of pyruvate metabolism (e.g., succinic acid) are not, or at least not significantly, affected during oscillation. Stoichiometric analysis of metabolic pathways confirms that other enzyme systems, in addition to pyruvate: formate-lyase, must be simultaneously involved in the pyruvate decarboxylation under both oscillation and steady-state conditions. The results strongly suggest oscillations of activities of these enzymes under oscillation conditions. It appears that the reason for the occurrence of oscillation and hysteresis lies in an unstable regulation of pyruvate metabolism of different enzymes triggered by substrate excess and drastic change(s) of environmental conditions.

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

    PubMed

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

    2015-08-04

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

  12. Sequential anaerobic, aerobic/anoxic treatment of simulated landfill leachate.

    PubMed

    Agdag, O N; Sponza, D T

    2008-02-01

    In this study COD, ammonia and nitrate were treated through methanogenesis, nitrification denitrification and anammox processes in anaerobic-aerobic and anaerobic/anoxic sequential in leachate samples produced from municipal solid waste in an anaerobic simulated landfilling bioreactor. The experiments were performed in an upflow anaerobic sludge blanket reactor (UASB), aerobic completely stirred tank reactor (CSTR) and upflow anaerobic/anoxic sludge blanket reactor (UA/A(N)SB). Hydraulic retention times in anaerobic, aerobic and anaerobic/anoxic stages were 1, 3.6 and 1 days, respectively, through 244 days of total operation period with 168 days of adaptation period of microorganisms to the reactors. The organic loading rates increased from 5.9 to 50 kg COD m(-3) day(-1). The total COD and TN removal efficiencies of the anaerobic-aerobic-anoxic system were 96% and 99%, respectively, at an influent OLR as high as 50 kg COD m(-3) day(-1). The maximum methane percentage in the UASB reactor was 82% while the methane percentage was zero in UA/A(N)SB reactor for the aforementioned OLR at the end of steady-state conditions. NH4-N removal efficiency of the aerobic reactor was 90% while anaerobic ammonia oxidation was measured as 99% in the anoxic reactor. The denitrification efficiency was 99% in the same reactor. Total TN removal of the whole system was 99%.

  13. Performance of a pilot-scale sewage treatment: an up-flow anaerobic sludge blanket (UASB) and a down-flow hanging sponge (DHS) reactors combined system by sulfur-redox reaction process under low-temperature conditions.

    PubMed

    Takahashi, Masanobu; Yamaguchi, Takashi; Kuramoto, Yoshiharu; Nagano, Akihiro; Shimozaki, Satoshi; Sumino, Haruhiko; Araki, Nobuo; Yamazaki, Shinichi; Kawakami, Shuji; Harada, Hideki

    2011-01-01

    Performance of a wastewater treatment system utilizing a sulfur-redox reaction of microbes was investigated using a pilot-scale reactor that was fed with actual sewage. The system consisted of an up-flow anaerobic sludge blanket (UASB) reactor and a down-flow hanging sponge (DHS) reactor with a recirculation line. Consequently, the total CODCr (465±147 mg L(-1); total BOD of 207±68 mg L(-1)) at the influent was reduced (70±14 mg L(-1); total BOD of 9±2 mg L(-1)) at the DHS effluent under the conditions of an overall hydraulic retention time of 12 h, a recirculation ratio of 2, and a low-sewage temperature of 7.0±2.8 °C. A microbial analysis revealed that sulfate-reducing bacteria contributed to the degradation of organic matter in the UASB reactor even in low temperatures. The utilized sulfur-redox reaction is applicable for low-strength wastewater treatment under low-temperature conditions. Copyright © 2010 Elsevier Ltd. All rights reserved.

  14. 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

  15. 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...

  16. 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...

  17. 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

  18. Pseudomonas aeruginosa anaerobic respiration in biofilms: relationships to cystic fibrosis pathogenesis.

    PubMed

    Yoon, Sang Sun; Hennigan, Robert F; Hilliard, George M; Ochsner, Urs A; Parvatiyar, Kislay; Kamani, Moneesha C; Allen, Holly L; DeKievit, Teresa R; Gardner, Paul R; Schwab, Ute; Rowe, John J; Iglewski, Barbara H; McDermott, Timothy R; Mason, Ronald P; Wozniak, Daniel J; Hancock, Robert E W; Parsek, Matthew R; Noah, Terry L; Boucher, Richard C; Hassett, Daniel J

    2002-10-01

    Recent data indicate that cystic fibrosis (CF) airway mucus is anaerobic. This suggests that Pseudomonas aeruginosa infection in CF reflects biofilm formation and persistence in an anaerobic environment. P. aeruginosa formed robust anaerobic biofilms, the viability of which requires rhl quorum sensing and nitric oxide (NO) reductase to modulate or prevent accumulation of toxic NO, a byproduct of anaerobic respiration. Proteomic analyses identified an outer membrane protein, OprF, that was upregulated approximately 40-fold under anaerobic versus aerobic conditions. Further, OprF exists in CF mucus, and CF patients raise antisera to OprF. An oprF mutant formed poor anaerobic biofilms, due, in part, to defects in anaerobic respiration. Thus, future investigations of CF pathogenesis and therapy should include a better understanding of anaerobic metabolism and biofilm development by P. aeruginosa.

  19. The effect of biological sulfate reduction on anaerobic color removal in anaerobic-aerobic sequencing batch reactors.

    PubMed

    Cirik, Kevser; Kitis, Mehmet; Cinar, Ozer

    2013-05-01

    Combination of anaerobic-aerobic sequencing processes result in both anaerobic color removal and aerobic aromatic amine removal during the treatment of dye-containing wastewaters. The aim of the present study was to gain more insight into the competitive biochemical reactions between sulfate and azo dye in the presence of glucose as electron donor source. For this aim, anaerobic-aerobic sequencing batch reactor fed with a simulated textile effluent including Remazol Brilliant Violet 5R (RBV 5R) azo dye was operated with a total cycle time of 12 h including anaerobic (6 h) and aerobic cycles (6 h). Microorganism grown under anaerobic phase of the reactor was exposed to different amounts of competitive electron acceptor (sulfate). Performance of the anaerobic phase was determined by monitoring color removal efficiency, oxidation reduction potential, color removal rate, chemical oxygen demand (COD), color, specific anaerobic enzyme (azo reductase) and aerobic enzyme (catechol 1,2-dioxygenase), and formation of aromatic amines. The presence of sulfate was not found to significantly affect dye decolorization. Sulfate and azo dye reductions took place simultaneously in all operational conditions and increase in the sulfate concentration generally stimulated the reduction of RBV 5R. However, sulfate accumulation under anaerobic conditions was observed proportional to increasing sulfate concentration.

  20. Proteome analysis of aerobically and anaerobically grown Saccharomyces cerevisiae cells.

    PubMed

    Bruckmann, Astrid; Hensbergen, Paul J; Balog, Crina I A; Deelder, André M; Brandt, Raymond; Snoek, I S Ishtar; Steensma, H Yde; van Heusden, G Paul H

    2009-01-30

    The yeast Saccharomyces cerevisiae is able to grow under aerobic as well as anaerobic conditions. We and others previously found that transcription levels of approximately 500 genes differed more than two-fold when cells from anaerobic and aerobic conditions were compared. Here, we addressed the effect of anaerobic growth at the post-transcriptional level by comparing the proteomes of cells isolated from steady-state glucose-limited anaerobic and aerobic cultures. Following two-dimensional gel electrophoresis and mass spectrometry we identified 110 protein spots, corresponding to 75 unique proteins, of which the levels differed more than two-fold between aerobically and anaerobically-grown cells. For 21 of the 110 spots, the intensities decreased more than two-fold whereas the corresponding mRNA levels increased or did not change significantly under anaerobic conditions. The intensities of the other 89 spots changed in the same direction as the mRNA levels of the corresponding genes, although to different extents. For some genes of glycolysis a small increase in mRNA levels, 1.5-2 fold, corresponded to a 5-10 fold increase in protein levels. Extrapolation of our results suggests that transcriptional regulation is the major but not exclusive mechanism for adaptation of S. cerevisiae to anaerobic growth conditions.

  1. Biodegradation of the nitramine explosives hexahydro-1,3,5-trinitro-1,3,5-triazine and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine in cold marine sediment under anaerobic and oligotrophic conditions.

    PubMed

    Zhao, Jian-Shen; Greer, Charles W; Thiboutot, Sonia; Ampleman, Guy; Hawari, Jalal

    2004-02-01

    The in situ degradation of the two nitramine explosives, hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), was evaluated using a mixture of RDX and HMX, incubated anaerobically at 10 degrees C with marine sediment from a previous military dumping site of unexploded ordnance (UXO) in Halifax Harbor, Nova Scotia, Canada. The RDX concentration (14.7 mg.L-1) in the aqueous phase was reduced by half in 4 days, while reduction of HMX concentration (1.2 mg.L-1) by half required 50 days. Supplementation with the carbon sources glucose, acetate, or citrate did not affect the removal rate of RDX but improved removal of HMX. Optimal mineralization of RDX and HMX was obtained in the presence of glucose. Using universally labeled (UL)-[14C]RDX, we obtained a carbon mass balance distributed as follows: CO2, 48%-58%; water soluble products, 27%-31%; acetonitrile extractable products, 2.0%-3.4%; and products covalently bound to the sediments and biomass, 8.9% (in the presence of glucose). The disappearance of RDX was accompanied by the formation of the mononitroso derivative hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine (MNX) and formaldehyde (HCHO) that subsequently disappeared. In the case of HMX, mineralization reached only 13%-27% after 115 days of incubation in the presence or absence of the carbon sources. The disappearance of HMX was also accompanied by the formation of the mononitroso derivative. The total population of psychrotrophic anaerobes that grew at 10 degrees C was 2.6 x 10(3) colony-forming units.(g sediment dry mass)-1, and some psychrotrophic sediment isolates were capable of degrading RDX under conditions similar to those used for sediments. Based on the distribution of products, we suggest that the sediment microorganisms degrade RDX and HMX via an initial reduction to the corresponding mononitroso derivative, followed by denitration and ring cleavage.

  2. 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.

  3. 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

  4. Fermentation and growth response of a primary poultry isolate of Salmonella typhimurium grown under strict anaerobic conditions in continuous culture and amino acid-limited batch culture.

    PubMed

    Maciorowski, K G; Nisbet, D J; Ha, S D; Corrier, D E; DeLoach, J R; Ricke, S C

    1997-01-01

    Salmonella typhimurium is a significant hazard to consumer health that is carried asymptomatically in poultry gastrointestinal tracts. Nurmi cultures may prevent Salmonella colonization in young chicks, but the mechanism of competitive exclusion is unclear. Modeling Salmonella's metabolism in pure culture may allow for greater definition in choosing strains for Nurmi cultures. The growth rates and affinity constants of S. typhimurium growing in amino acid-limited conditions were determined in batch culture and compared to primary poultry isolates of cecal strains. Serine and NH4Cl were the best N sources for growth of all organisms tested in this study. The fermentation response of S. typhimurium was also monitored in continuous culture at a slow dilution rate of 0.021 h-1. S. typhimurium was found to adapt to VL media, with trends in protein disappearance, Yglucose, and Yprotein. This may show that amino acid or protein concentrations may be an integral component of the initial establishment of S. typhimurium in the cecum.

  5. 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.

  6. Anaerobic Catabolism of Aromatic Compounds: a Genetic and Genomic View

    PubMed Central

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

    2009-01-01

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

  7. The effect of microbial sulfidogenesis on the stability of As-Fe coprecipitate with low Fe/As molar ratio under anaerobic conditions.

    PubMed

    Wang, Shaofeng; He, Xin Yu; Pan, Rongrong; Xu, Liying; Wang, Xin; Jia, Yongfeng

    2016-04-01

    The effect of microbial sulfidogenesis on As transformation and mobilization in solid phase with low Fe/As ratio is still not well known. In this study, microbial transformation and mobilization of As in the As-Fe coprecipitate with different sulfate levels were investigated using chemical extraction and K-edge XANES of As and S. Results showed that approximately 2.7, 24.4, and 83.7 % of total As were released into the aqueous phase in the low-, mid-, and high-sulfate treatments, respectively, indicating that the presence of large amounts of sulfate could enhance microbial arsenic mobilization in the As-Fe coprecipitate. In the low-sulfate treatment, As mobilization was primarily attributed to the reductive dissolution of the Fe (oxy)hydroxides and the As reduction and desorption. In the mid- and high-sulfate treatments, the reduction of arsenate and ferric iron was significantly enhanced. Complete ferric iron reduction was observed in the solid phase, implying that Fe (oxy)hydroxide was transformed to secondary minerals and may be the one of the primary causes for the enhanced As mobilization. Thermodynamic calculations predicted the formation of thioarsenite species after 35 days of incubation based on the concentration of dissolved As(III) and S(-II). Since thioarsenic species is more mobile, its formation may be one of the most important factors enhancing the As release in the high-sulfate system. The result of this study is of significance to completely predict the environmental behavior of As associated with Fe (hydr)oxides in the presence of microbial sulfidogenesis under anoxic conditions.

  8. Thermodynamics of substrate binding to the metal site in homoprotocatechuate 2,3-dioxygenase: Using ITC under anaerobic conditions to study enzyme-substrate interactions.

    PubMed

    Henderson, Kate L; Francis, Danielle H; Lewis, Edwin A; Emerson, Joseph P

    2016-05-01

    Extradiol dioxygenases are a family of nonheme iron (and sometimes manganese) enzymes that catalyze an O2-dependent ring-opening reaction in a biodegradation pathway of aromatic compounds. Here we characterize the thermodynamics of two substrates binding in homoprotocatechuate 2,3-dioxygenase (HPCD) prior to the O2 activation step. This study uses microcalorimetry under an inert atmosphere to measure thermodynamic parameters associated with catechol binding to nonheme metal centers in HPCD. Several stopped-flow rapid mixing experiments were used to support the calorimetry experiments. The equilibria constant for 4-nitrocatechol and homoprotocatechuate binding to the iron(II) and manganese(II) forms of HPCD range from 2×10(4) to 1×10(6), suggesting there are distinctive differences in how the enzyme-substrate complexes are stabilized. Further experiments in multiple buffers allowed us to correct the experimental ΔH for substrate ionization and to fully derive the pH and buffer independent thermodynamic parameters for substrate binding to HPCD. Fewer protons are released from the iron(II) dependent processes than their manganese(II) counterparts. Condition independent thermodynamic parameters for 4-nitrocatechol and homoprotocatechuate binding to HPCD are highly consistent with each other, suggesting these enzyme-substrate complexes are more similar than once thought, and the ionization state of metal coordinated waters may be playing a role in tuning redox potential and in governing reactivity. Substrate binding to HPCD is a complex set of equilibria that includes ionization of substrate and water release, yet it is also the key step in O2 activation. Copyright © 2015. Published by Elsevier B.V.

  9. Anaerobic Degradation of Cyanuric Acid, Cysteine, and Atrazine by a Facultative Anaerobic Bacterium

    PubMed Central

    Jessee, J. A.; Benoit, R. E.; Hendricks, A. C.; Allen, G. C.; Neal, J. L.

    1983-01-01

    A facultative anaerobic bacterium that rapidly degrades cyanuric acid (CA) was isolated from the sediment of a stream that received industrial wastewater effluent. CA decomposition was measured throughout the growth cycle by using a high-performance liquid chromatography assay, and the concomitant production of ammonia was also measured. The bacterium used CA or cysteine as a major, if not the sole, carbon and energy source under anaerobic, but not aerobic, conditions in a defined medium. The cell yield was greatly enhanced by the simultaneous presence of cysteine and CA in the medium. Cysteine was preferentially used rather than CA early in the growth cycle, but all of the CA was used without an apparent lag after the cysteine was metabolized. Atrazine was also degraded by this bacterium under anaerobic conditions in a defined medium. PMID:16346187

  10. Anaerobic biodegradation of (emerging) organic contaminants in the aquatic environment.

    PubMed

    Ghattas, Ann-Kathrin; Fischer, Ferdinand; Wick, Arne; Ternes, Thomas A

    2017-06-01

    Although strictly anaerobic conditions prevail in several environmental compartments, up to now, biodegradation studies with emerging organic contaminants (EOCs), such as pharmaceuticals and personal care products, have mainly focused on aerobic conditions. One of the reasons probably is the assumption that the aerobic degradation is more energetically favorable than degradation under strictly anaerobic conditions. Certain aerobically recalcitrant contaminants, however, are biodegraded under strictly anaerobic conditions and little is known about the organisms and enzymatic processes involved in their degradation. This review provides a comprehensive survey of characteristic anaerobic biotransformation reactions for a variety of well-studied, structurally rather simple contaminants (SMOCs) bearing one or a few different functional groups/structural moieties. Furthermore it summarizes anaerobic degradation studies of more complex contaminants with several functional groups (CMCs), in soil, sediment and wastewater treatment. While strictly anaerobic conditions are able to promote the transformation of several aerobically persistent contaminants, the variety of observed reactions is limited, with reductive dehalogenations and the cleavage of ether bonds being the most prevalent. Thus, it becomes clear that the transferability of degradation mechanisms deduced from culture studies of SMOCs to predict the degradation of CMCs, such as EOCs, in environmental matrices is hampered due the more complex chemical structure bearing different functional groups, different environmental conditions (e.g. matrix, redox, pH), the microbial community (e.g. adaptation, competition) and the low concentrations typical for EOCs. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  11. [Anaerobic growth ability and alcohol fermentation activity of microscopic fungi].

    PubMed

    Kurakov, A V; Khidirov, K S; Sadykova, V S; Zviagintsev, D G

    2011-01-01

    The method proposed in this study was used to isolate fungi grown under anaerobic conditions and to reveal distinctions in their abundance and species composition in different habitats. The ability of micromycetes of different taxa to grow under anaerobic conditions and ensure alcohol fermentation was determined for a representative sample (344 strains belonging to more than 60 species). The group of fungi growing under anaerobic conditions included species with high, moderate, and low fermentation activity. The ability for anaerobic growth and fermentation depended on the taxonomic affiliation of fungi. In some cases, the expression of these characteristics depended on the habitat from which the strain was isolated. The maximum level of ethanol accumulation in culture liquid (1.2-4.7%) was detected for Absidia spinosa, Aspergillus sp. of group flavus, Aspergillus terreus, Acremonium sp., Mucor circinelloides, Mucor sp., Fusarium oxysporum, F. solani, F. sambucinum, Rhizopus arrhizus var. Arrhizus, Trichoderma atroviride, and Trichoderma sp.

  12. Calorimetric studies of the growth of anaerobic microbes.

    PubMed

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

    2016-09-01

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

  13. Anaerobic Antimicrobial Therapy After Necrotizing Enterocolitis in VLBW Infants

    PubMed Central

    Autmizguine, Julie; Hornik, Christoph P.; Benjamin, Daniel K.; Laughon, Matthew M.; Clark, Reese H.; Cotten, C. Michael; Cohen-Wolkowiez, Michael; Benjamin, Daniel K.

    2015-01-01

    OBJECTIVE: To evaluate the effect of anaerobic antimicrobial therapy for necrotizing enterocolitis (NEC) on clinical outcomes in very low birth weight (≤1500 g) infants. METHODS: We identified very low birth weight infants with NEC from 348 US NICUs from 1997 to 2012. Anaerobic antimicrobial therapy was defined by antibiotic exposure on the first day of NEC. We matched (1:1) infants exposed to anaerobic antimicrobial therapy with infants who were not exposed by using a propensity score stratified by NEC severity (medical and surgical). The primary composite outcome was in-hospital death or intestinal stricture. We assessed the relationship between anaerobic antimicrobial therapy and outcome by using a conditional logistic regression on the matched cohort. RESULTS: A total of 1390 infants exposed to anaerobic antimicrobial therapy were matched with 1390 infants not exposed. Mean gestational age and birth weight were 27 weeks and 946 g, respectively, and were similar in both groups. We found no significant difference in the combined outcome of death or strictures, but strictures as a single outcome were more common in the anaerobic antimicrobial therapy group (odds ratio 1.73; 95% confidence interval, 1.11–2.72). Among infants with surgical NEC, mortality was less common with anaerobic antimicrobial therapy (odds ratio 0.71; 95% confidence interval, 0.52–0.95). CONCLUSIONS: Anaerobic antimicrobial therapy was not associated with the composite outcome of death or strictures but was associated with an increase in intestinal strictures. This higher incidence of intestinal strictures may be explained by the fact that death is a competing outcome for intestinal strictures, and mortality was slightly lower in the anaerobic cohort. Infants with surgical NEC who received anaerobic antimicrobial therapy had lower mortality. PMID:25511117

  14. Anaerobic biodegradation of surrogate naphthenic acids.

    PubMed

    Clothier, Lindsay N; Gieg, Lisa M

    2016-03-01

    Surface bitumen extraction from the Alberta's oil sands region generates large settling basins known as tailings ponds. The oil sands process-affected water (OSPW) stored in these ponds contain solid and residual bitumen-associated compounds including naphthenic acids (NAs) that can potentially be biodedgraded by indigenous tailings microorganisms. While the biodegradation of some NAs is known to occur under aerobic conditions, little is understood about anaerobic NA biodegradation even though tailings ponds are mainly anoxic. Here, we investigated the potential for anaerobic NA biodegradation by indigenous tailings microorganisms. Enrichment cultures were established from anoxic tailings that were amended with 5 single-ringed surrogate NAs or acid-extractable organics (AEO) from OSPW and incubated under nitrate-, sulfate-, iron-reducing, and methanogenic conditions. Surrogate NA depletion was observed under all anaerobic conditions tested to varying extents, correlating to losses in the respective electron acceptor (sulfate or nitrate) or the production of predicted products (Fe(II) or methane). Tailings-containing cultures incubated under the different electron-accepting conditions resulted in the enrichment and putative identification of microbial community members that may function in metabolizing surrogate NAs under the various anoxic conditions. In addition, more complex NAs (in the form of AEO) was observed to drive sulfate and iron reduction relative to controls. Overall, this study has shown that simple surrogate NAs can be biodegraded under a variety of anoxic conditions, a key first step in understanding the potential anaerobic metabolism of NAs in oil sands tailings ponds and other industrial wastewaters. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Improve bio-activity of anaerobic sludge by low energy ultrasound.

    PubMed

    Zhu, Yichun; Li, Xin; Du, Maoan; Liu, Zuwen; Luo, Hui; Zhang, Tao

    2015-01-01

    This research focused on ultrasound-enhanced bio-activity of anaerobic sludge. Low energy ultrasound irradiation can increase the bio-activity of anaerobic sludge. Ultrasonic parameter, characteristics of anaerobic sludge and experimental conditions are important parameters which affect the enhancement effect on anaerobic sludge. In order to assess the effects of characteristics of anaerobic sludge and experimental conditions on ultrasonic irradiation of anaerobic sludge, experiments with different characteristics of anaerobic sludge were carried out and analyzed with the content of coenzyme F420 and dehydrogenase activity (DHA). The results showed that anaerobic sludge bio-activity was impacted by the initial temperature, initial chemical oxygen demand (COD), sludge concentration, and stirring during the ultrasonic process. Optimal performance was achieved when sound frequency, power density, and ultrasonic irradiation period was 20 kHz, 0.1 W/mL, and 10 min, respectively, under which the wastewater COD removal efficiency was increased by 12.9 percentage points. The results indicated that low temperature could affect the anaerobic sludge irradiation effect, while intermittent stirring could enhance the bio-activity of anaerobic sludge irradiation effect and low substrate concentration improved anaerobic sludge activity by ultrasound.

  16. Neural fuzzy modeling of anaerobic biological wastewater treatment systems

    SciTech Connect

    Tay, J.H.; Zhang, X.

    1999-12-01

    Anaerobic biological wastewater treatment systems are difficult to model because their performance is complex and varies significantly with different reactor configurations, influent characteristics, and operational conditions. Instead of conventional kinetic modeling, advanced neural fuzzy technology was employed to develop a conceptual adaptive model for anaerobic treatment systems. The conceptual neural fuzzy model contains the robustness of fuzzy systems, the learning ability of neural networks, and can adapt to various situations. The conceptual model was used to simulate the daily performance of two high-rate anaerobic wastewater treatment systems with satisfactory results obtained.

  17. 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.

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

    PubMed Central

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

    2015-01-01

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

  19. 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.

  20. Characterizing the Anaerobic Response of Chlamydomonas reinhardtii by Quantitative Proteomics

    PubMed Central

    Terashima, Mia; Specht, Michael; Naumann, Bianca; Hippler, Michael

    2010-01-01

    The versatile metabolism of the green alga Chlamydomonas reinhardtii is reflected in its complex response to anaerobic conditions. The anaerobic response is also remarkable in the context of renewable energy because C. reinhardtii is able to produce hydrogen under anaerobic conditions. To identify proteins involved during anaerobic acclimation as well as to localize proteins and pathways to the powerhouses of the cell, chloroplasts and mitochondria from C. reinhardtii in aerobic and anaerobic (induced by 8 h of argon bubbling) conditions were isolated and analyzed using comparative proteomics. A total of 2315 proteins were identified. Further analysis based on spectral counting clearly localized 606 of these proteins to the chloroplast, including many proteins of the fermentative metabolism. Comparative quantitative analyses were performed with the chloroplast-localized proteins using stable isotopic labeling of amino acids ([13C6]arginine/[12C6]arginine in an arginine auxotrophic strain). The quantitative data confirmed proteins previously characterized as induced at the transcript level as well as identified several new proteins of unknown function induced under anaerobic conditions. These proteins of unknown function provide new candidates for further investigation, which could bring insights for the engineering of hydrogen-producing alga strains. PMID:20190198

  1. 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

  2. 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

  3. Modeling for Anaerobic Fixed-Bed Biofilm Reactors

    SciTech Connect

    Liu, B. Y. M.; Pfeffer, J. T.

    1989-06-01

    The specific objectives of this research were: 1. to develop an equilibrium model for chemical aspects of anaerobic reactors; 2. to modify the equilibrium model for non-equilibrium conditions; 3. to incorporate the existing biofilm models into the models above to study the biological and chemical behavior of the fixed-film anaerobic reactors; 4. to experimentally verify the validity of these models; 5. to investigate the biomass-holding ability of difference packing materials for establishing reactor design criteria.

  4. Effect of alkaline pretreatment on anaerobic digestion of solid wastes

    SciTech Connect

    Lopez Torres, M. Espinosa Llorens, Ma. del C.

    2008-11-15

    The introduction of the anaerobic digestion for the treatment of the organic fraction of municipal solid waste (OFMSW) is currently of special interest. The main difficulty in the treatment of this waste fraction is its biotransformation, due to the complexity of organic material. Therefore, the first step must be its physical, chemical and biological pretreatment for breaking complex molecules into simple monomers, to increase solubilization of organic material and improve the efficiency of the anaerobic treatment in the second step. This paper describes chemical pretreatment based on lime addition (Ca(OH){sub 2}), in order to enhance chemical oxygen demand (COD) solubilization, followed by anaerobic digestion of the OFMSW. Laboratory-scale experiments were carried out in completely mixed reactors, 1 L capacity. Optimal conditions for COD solubilization in the first step of pretreatment were 62.0 mEq Ca(OH){sub 2}/L for 6.0 h. Under these conditions, 11.5% of the COD was solubilized. The anaerobic digestion efficiency of the OFMSW, with and without pretreatment, was evaluated. The highest methane yield under anaerobic digestion of the pretreated waste was 0.15 m{sup 3} CH{sub 4}/kg volatile solids (VS), 172.0% of the control. Under that condition the soluble COD and VS removal were 93.0% and 94.0%, respectively. The results have shown that chemical pretreatment with lime, followed by anaerobic digestion, provides the best results for stabilizing the OFMSW.

  5. Carbon and Hydrogen Isotopic Fractionation during Anaerobic Biodegradation of Benzene

    PubMed Central

    Mancini, Silvia A.; Ulrich, Ania C.; Lacrampe-Couloume, Georges; Sleep, Brent; Edwards, Elizabeth A.; Sherwood Lollar, Barbara

    2003-01-01

    Compound-specific isotope analysis has the potential to distinguish physical from biological attenuation processes in the subsurface. In this study, carbon and hydrogen isotopic fractionation effects during biodegradation of benzene under anaerobic conditions with different terminal-electron-accepting processes are reported for the first time. Different enrichment factors (ɛ) for carbon (range of −1.9 to −3.6‰) and hydrogen (range of −29 to −79‰) fractionation were observed during biodegradation of benzene under nitrate-reducing, sulfate-reducing, and methanogenic conditions. These differences are not related to differences in initial biomass or in rates of biodegradation. Carbon isotopic enrichment factors for anaerobic benzene biodegradation in this study are comparable to those previously published for aerobic benzene biodegradation. In contrast, hydrogen enrichment factors determined for anaerobic benzene biodegradation are significantly larger than those previously published for benzene biodegradation under aerobic conditions. A fundamental difference in the previously proposed initial step of aerobic versus proposed anaerobic biodegradation pathways may account for these differences in hydrogen isotopic fractionation. Potentially, C-H bond breakage in the initial step of the anaerobic benzene biodegradation pathway may account for the large fractionation observed compared to that in aerobic benzene biodegradation. Despite some differences in reported enrichment factors between cultures with different terminal-electron-accepting processes, carbon and hydrogen isotope analysis has the potential to provide direct evidence of anaerobic biodegradation of benzene in the field. PMID:12513995

  6. Anaerobically expressed Escherichia coli genes identified by operon fusion techniques.

    PubMed Central

    Choe, M; Reznikoff, W S

    1991-01-01

    Genes that are expressed under anaerobic conditions were identified by operon fusion techniques with a hybrid bacteriophage of lambda and Mu, lambda placMu53, which creates transcriptional fusions to lacZY. Cells were screened for anaerobic expression on XG medium. Nine strains were selected, and the insertion point of the hybrid phage in each strain was mapped on the Escherichia coli chromosome linkage map. The anaerobic and aerobic expression levels of these genes were measured by beta-galactosidase assays in different medium conditions and in the presence of three regulatory mutations (fnr, narL, and rpoN). The anaerobically expressed genes (aeg) located at minute 99 (aeg-99) and 75 (aeg-75) appeared to be partially regulated by fnr, and aeg-93 is tightly regulated by fnr. aeg-60 requires a functional rpoN gene for its anaerobic expression. aeg-46.5 is repressed by narL. aeg-65A and aeg-65C are partially controlled by fnr but only in media containing nitrate or fumarate. aeg-47.5 and aeg-48.5 were found to be anaerobically induced only in rich media. The effects of a narL mutation on aeg-46.5 expression were observed in all medium conditions regardless of the presence or absence of nitrate. This suggests that narL has a regulatory function in the absence of exogenously added nitrate. PMID:1917846

  7. Anaerobic Biodegradation of Soybean Biodiesel and Diesel ...

    EPA Pesticide Factsheets

    Biotransformation of soybean biodiesel and the inhibitory effect of petrodiesel were studied under methanogenic conditions. Biodiesel removal efficiency of more than 95% was achieved in a chemostat with influent biodiesel concentrations up to 2.45 g/L. The kinetics of anaerobic biodegradation of soybean biodiesel B100 (biodiesel only) with different petrodiesel loads were studied using biomass pre-acclimated to B100 and B80 (80% biodiesel and 20 petrodiesel). The results indicated that the biodiesel fraction of the blend could be effectively biodegraded, whereas petrodiesel was not biodegraded at all under methanogenic conditions. The presence of petrodiesel in blends with biodiesel had a greater inhibitory effect on the rate of biodegradation than the biodegradation efficiency (defined as the efficiency of methane production). Both the biodegradation rate coefficient and the methane production efficiency increased almost linearly with the increasing fraction of biodiesel. With the increasing fraction of petrodiesel, the biodegradation rate and efficiency were correlated with the concentration of soluble FAMEs in the water. The objective of this study was to investigate the anaerobic biodegradation of soybean biodiesel blends under methanogenic conditions. Biological methane potential (BMP) tests were conducted in serum bottles to determine the anaerobic biodegradation kinetics of biodiesel in the absence and presence of different concentrations of petrod

  8. Anaerobic digestion for sustainable development: a natural approach.

    PubMed

    Gljzen, H J

    2002-01-01

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

  9. Improvement of anaerobic digestion of sludge.

    PubMed

    Dohányos, M; Zábranská, J; Kutil, J; Jenícek, P

    2004-01-01

    Anaerobic digestion improvement can be accomplished by different methods. Besides optimization of the process conditions, pretreatment of input sludge and increase of process temperature is frequently used. The thermophilic process brings a higher solids reduction and biogas production, a high resistance to foaming, no problems with odour, better pathogens destruction and an improvement of the energy balance of the whole treatment plant. Disintegration of excess activated sludge in a lysate centrifuge was proved to cause increase of biogas production in full-scale conditions. The rapid thermal conditioning of digested sludge is an acceptable method of particulate matter disintegration and solubilization.

  10. 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.

  11. Comparison of microbial activity in anaerobic and microaerobic digesters.

    PubMed

    Jenicek, P; Celis, C A; Koubova, J; Pokorna, D

    2011-01-01

    Microaerobic alternative of anaerobic digestion offers many advantages especially when sulfide concentration in the digester is high. For better understanding of the microaerobic technology more detailed characterization of biomass activity is needed. Two equal digesters were operated under the same condition except of microaeration in one of them. During long term operation of anaerobic and microaerobic digesters the sludge quality and the biomass activity was monitored. The activity of sulfide oxidizing bacteria of microaerobic biomass was significantly higher in comparison with anaerobic biomass. The activity of sulfate reducing bacteria was comparable. The activity of methanogenic bacteria activity depended on sulfide concentration more than on microaeration. The extent of foaming problems was lower in the microaerobic than in the anaerobic digester.

  12. Characteristics, process parameters, and inner components of anaerobic bioreactors.

    PubMed

    Abdelgadir, Awad; Chen, Xiaoguang; Liu, Jianshe; Xie, Xuehui; Zhang, Jian; Zhang, Kai; Wang, Heng; Liu, Na

    2014-01-01

    The anaerobic bioreactor applies the principles of biotechnology and microbiology, and nowadays it has been used widely in the wastewater treatment plants due to their high efficiency, low energy use, and green energy generation. Advantages and disadvantages of anaerobic process were shown, and three main characteristics of anaerobic bioreactor (AB), namely, inhomogeneous system, time instability, and space instability were also discussed in this work. For high efficiency of wastewater treatment, the process parameters of anaerobic digestion, such as temperature, pH, Hydraulic retention time (HRT), Organic Loading Rate (OLR), and sludge retention time (SRT) were introduced to take into account the optimum conditions for living, growth, and multiplication of bacteria. The inner components, which can improve SRT, and even enhance mass transfer, were also explained and have been divided into transverse inner components, longitudinal inner components, and biofilm-packing material. At last, the newly developed special inner components were discussed and found more efficient and productive.

  13. Characteristics, Process Parameters, and Inner Components of Anaerobic Bioreactors

    PubMed Central

    Abdelgadir, Awad; Chen, Xiaoguang; Liu, Jianshe; Xie, Xuehui; Zhang, Jian; Zhang, Kai; Wang, Heng; Liu, Na

    2014-01-01

    The anaerobic bioreactor applies the principles of biotechnology and microbiology, and nowadays it has been used widely in the wastewater treatment plants due to their high efficiency, low energy use, and green energy generation. Advantages and disadvantages of anaerobic process were shown, and three main characteristics of anaerobic bioreactor (AB), namely, inhomogeneous system, time instability, and space instability were also discussed in this work. For high efficiency of wastewater treatment, the process parameters of anaerobic digestion, such as temperature, pH, Hydraulic retention time (HRT), Organic Loading Rate (OLR), and sludge retention time (SRT) were introduced to take into account the optimum conditions for living, growth, and multiplication of bacteria. The inner components, which can improve SRT, and even enhance mass transfer, were also explained and have been divided into transverse inner components, longitudinal inner components, and biofilm-packing material. At last, the newly developed special inner components were discussed and found more efficient and productive. PMID:24672798

  14. Oxygen tolerance capacity of upflow anaerobic solid-state (UASS) with anaerobic filter (AF) system.

    PubMed

    Meng, Yao; Jost, Carsten; Mumme, Jan; Wang, Kaijun; Linke, Bernd

    2016-07-01

    In order to investigate the oxygen tolerance capacity of upflow anaerobic solid-state (UASS) with anaerobic filter (AF) system, the effect of microaeration on thermophilic anaerobic digestion of maize straw was investigated under batch conditions and in the UASS with AF system. Aeration intensities of 0-431mL O2/gvs were conducted as pretreatment under batch conditions. Aeration pretreatment obviously enhanced anaerobic digestion and an aeration intensity of 431mL O2/gvs increased the methane yield by 82.2%. Aeration intensities of 0-355mL O2/gvs were conducted in the process liquor circulation of the UASS with AF system. Dissolved oxygen (DO) of UASS and AF reactors kept around 1.39±0.27 and 0.99±0.38mg/L, respectively. pH was relatively stable around 7.11±0.04. Volatile fatty acids and soluble chemical oxygen demand concentration in UASS reactor were higher than those in AF reactor. Methane yield of the whole system was almost stable at 85±7mL/gvs as aeration intensity increased step by step. The UASS with AF system showed good oxygen tolerance capacity. Copyright © 2016. Published by Elsevier B.V.

  15. 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.

  16. 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.

  17. Anaerobic bioventing of unsaturated zone contaminated with DDT and DNT.

    PubMed

    Shah, J K; Sayles, G D; Suidan, M T; Mihopoulos, P; Kaskassian, S

    2001-01-01

    Initial degradation of highly chlorinated compounds and nitroaromatic compounds found in munition waste streams is accelerated under anaerobic conditions followed by aerobic treatment of the degradation products. The establishment of anaerobic environment in a vadose zone can be accomplished by feeding appropriate anaerobic gas mixture, i.e., "anaerobic bioventing". The gas mixture contains an electron donor for the reduction of these compounds. Lab scale study was conducted to evaluate potential of anaerobic bioventing for the treatment of an unsaturated zone contaminated with 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and 2,4-dinitrotoluene (DNT). Hydrogen was used as the electron donor. Using the soil columns innoculate with anaerobic microorganisms, it was observed that by feeding a gas mixture of 1% hydrogen, 1% carbon dioxide and nitrogen, methanogenic conditions were established and DDT was reductively dechlorinated. 1,1-dichloro-2,2-bis(p-chlorophenyl)ethane (DDD) accumulated as the intermediate product. The half life of DDT was calculated to be 8.5 months. DNT completely disappeared after six months of operation and no intermediates could be detected.

  18. Biogeochemistry of anaerobic crude oil biodegradation

    NASA Astrophysics Data System (ADS)

    Head, Ian; Gray, Neil; Aitken, Caroline; Sherry, Angela; Jones, Martin; Larter, Stephen

    2010-05-01

    Anaerobic degradation of crude oil and petroleum hydrocarbons is widely recognized as a globally significant process both in the formation of the world's vast heavy oil deposits and for the dissipation of hydrocarbon pollution in anoxic contaminated environments. Comparative analysis of crude oil biodegradation under methanogenic and sulfate-reducing conditions has revealed differences not only in the patterns of compound class removal but also in the microbial communities responsible. Under methanogenic conditions syntrophic associations dominated by bacteria from the Syntropheaceae are prevalent and these are likely key players in the initial anaerobic degradation of crude oil alkanes to intermediates such as hydrogen and acetate. Syntrophic acetate oxidation plays an important role in these systems and often results in methanogenesis dominated by CO2 reduction by members of the Methanomicrobiales. By contrast the bacterial communities from sulfate-reducing crude oil-degrading systems were more diverse and no single taxon dominated the oil-degrading sulfate-reducing systems. All five proteobacterial subdivisions were represented with Delta- and Gammaproteobacteria being detected most consistently. In sediments which were pasteurized hydrocarbon degradation continued at a relatively low rate. Nevertheless, alkylsuccinates characteristic of anaerobic hydrocarbon degradation accumulated to high concentrations. This suggested that the sediments harbour heat resistant, possibly spore-forming alkane degrading sulfate-reducers. This is particularly interesting since it has been proposed recently, that spore-forming sulfate-reducing bacteria found in cold arctic sediments may have originated from seepage of geofluids from deep subsurface hydrocarbon reservoirs.

  19. 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

  20. Redesigning Escherichia coli metabolism for anaerobic production of isobutanol.

    PubMed

    Trinh, Cong T; Li, Johnny; Blanch, Harvey W; Clark, Douglas S

    2011-07-01

    Fermentation enables the production of reduced metabolites, such as the biofuels ethanol and butanol, from fermentable sugars. This work demonstrates a general approach for designing and constructing a production host that uses a heterologous pathway as an obligately fermentative pathway to produce reduced metabolites, specifically, the biofuel isobutanol. Elementary mode analysis was applied to design an Escherichia coli strain optimized for isobutanol production under strictly anaerobic conditions. The central metabolism of E. coli was decomposed into 38,219 functional, unique, and elementary modes (EMs). The model predictions revealed that during anaerobic growth E. coli cannot produce isobutanol as the sole fermentative product. By deleting 7 chromosomal genes, the total 38,219 EMs were constrained to 12 EMs, 6 of which can produce high yields of isobutanol in a range from 0.29 to 0.41 g isobutanol/g glucose under anaerobic conditions. The remaining 6 EMs rely primarily on the pyruvate dehydrogenase enzyme complex (PDHC) and are typically inhibited under anaerobic conditions. The redesigned E. coli strain was constrained to employ the anaerobic isobutanol pathways through deletion of 7 chromosomal genes, addition of 2 heterologous genes, and overexpression of 5 genes. Here we present the design, construction, and characterization of an isobutanol-producing E. coli strain to illustrate the approach. The model predictions are evaluated in relation to experimental data and strategies proposed to improve anaerobic isobutanol production. We also show that the endogenous alcohol/aldehyde dehydrogenase AdhE is the key enzyme responsible for the production of isobutanol and ethanol under anaerobic conditions. The glycolytic flux can be controlled to regulate the ratio of isobutanol to ethanol production.

  1. 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.

  2. 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

  3. Identification of a conserved protein involved in anaerobic unsaturated fatty acid synthesis in Neiserria gonorrhoeae: implications for facultative and obligate anaerobes that lack FabA.

    PubMed

    Isabella, Vincent M; Clark, Virginia L

    2011-10-01

    Transcriptome analysis of the facultative anaerobe, Neisseria gonorrhoeae, revealed that many genes of unknown function were induced under anaerobic conditions. Mutation of one such gene, NGO1024, encoding a protein belonging to the 2-nitropropane dioxygenase-like superfamily of proteins, was found to result in an inability of gonococci to grow anaerobically. Anaerobic growth of an NG1024 mutant was restored upon supplementation with unsaturated fatty acids (UFA), but not with the saturated fatty acid palmitate. Gonococcal fatty acid profiles confirmed that NGO1024 was involved in UFA synthesis anaerobically, but not aerobically, demonstrating that gonococci contain two distinct pathways for the production of UFAs, with a yet unidentified aerobic mechanism, and an anaerobic mechanism involving NGO1024. Expression of genes involved in classical anaerobic UFA synthesis, fabA, fabM and fabB, was toxic in gonococci and unable to complement a NGO1024 mutation, suggesting that the chemistry involved in gonococcal anaerobic UFA synthesis is distinct from that of the classical pathway. NGO1024 homologues, which we suggest naming UfaA, form a distinct lineage within the 2-nitropropane dioxygenase-like superfamily, and are found in many facultative and obligate anaerobes that produce UFAs but lack fabA, suggesting that UfaA is part of a widespread pathway involved in UFA synthesis.

  4. 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.

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

    PubMed

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

    2017-03-01

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

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

    SciTech Connect

    Mendes, Carlos Esquerre, Karla Matos Queiroz, Luciano

    2015-01-15

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

  7. Anaerobic treatability of wastewater contaminated with propylene glycol.

    PubMed

    Sezgin, Naim; Tonuk, Gulseven Ubay

    2013-09-01

    The purpose of this study was to investigate the biodegradability of propylene glycol in anaerobic conditions by using methanogenic culture. A master reactor was set up to develop a culture that would be acclimated to propylene glycol. After reaching steady-state, culture was transferred to serum bottles. Three reactors with same initial conditions were run for consistency. Propylene glycol was completely biodegradable under anaerobic methanogenic conditions. Semi-continuous reactors operated at a temperature of 35°C had consistently achieved a propylene glycol removal of higher than 95 % based on chemical oxygen demand (COD). It was found that in semi-continuous reactors, anaerobic treatment of propylene glycol at concentrations higher than 1,500 mg COD m(-3) day(-1) was not convenient due to instable effluent COD.

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

    PubMed

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

    2013-02-01

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

  9. Comparison of selected aerobic and anaerobic procedures for MSW treatment.

    PubMed

    Fricke, Klaus; Santen, Heike; Wallmann, Rainer

    2005-01-01

    This paper considers selected efficiency rates and process data of aerobic and anaerobic procedures for the treatment of municipal solid waste and residual waste. Data are exclusively related to mechanical-biological treatment (MBT) procedures for generating waste appropriate for landfilling. The following aspects are regarded: general framework conditions for the application of MBT, efficiency of decomposition and of stabilisation, air and water emissions and energy balances. The presented data can be used for more efficient planning. In comparison to aerobic processes, anaerobic digestion can be ecologically advantageous, particularly with regard to exhaust emissions and energy balances. On the other hand, the wastewater emissions and the wastewater treatment required must be regarded as disadvantageous. Due to the relatively short period of operational history of most anaerobic processes for mechanical-biological waste treatment and thus limited experiences, operational reliability of anaerobic processes is slightly lower. Extensive biological stability of the treated waste for low-emission disposal cannot be reached by anaerobic digestion alone, but only in combination with additional aerobic post-treatment. In connection with the utilisation of renewable energies and the rising relevancy of climate protection, it can be affirmed that anaerobic digestion for the treatment of municipal solid waste has a high potential for further development.

  10. C4-Dicarboxylate Degradation in Aerobic and Anaerobic Growth.

    PubMed

    Unden, Gottfried; Kleefeld, Alexandra

    2004-12-01

    C4-dicarboxylates, like succinate, fumarate, L- and D-malate, tartrate, and the C4-dicarboxylic amino acid aspartate, support aerobic and anaerobic growth of Escherichia coli and related bacteria and can serve as carbon and energy sources. In aerobic growth, the C4-dicarboxylates are oxidized in the citric acid cycle. Due to the interruption of the citric acid cycle under anaerobic conditions, anaerobic metabolism of the C4-dicarboxylates depends on fumarate reduction to succinate. In some related bacteria (e.g., Klebsiella), degradation of C4-dicarboxylates, like tartrate, uses a different mechanism and pathway. It requires the functioning of an Na+-dependent and membrane-associated oxaloacetate decarboxylase. Due to the incomplete function of the citric acid cycle in anaerobic growth, succinate supports only aerobic growth of E. coli. This chapter describes the pathways of and differences in aerobic and anaerobic C4-dicarboxylate metabolism and the physiological consequences. The citric acid cycle, fumarate respiration, and fumarate reductase are discussed here only in the context of aerobic and anaerobic C4-dicarboxylate metabolism. Some recent aspects of C4-dicarboxylate metabolism, such as transport and sensing of C4-dicarboxylates, and their relationships are treated in more detail.

  11. Anaerobic treatment of aircraft deicing wastes: A technology assessment. Final report

    SciTech Connect

    1998-09-01

    The work contained in the study documents the fact that deicing wastes containing ethylene glycol (EG) and propylene glycol (PG) may be effectively treated using an anaerobic biological process. In the report, the treatment of aircraft deicing wastes under anaerobic methanogenic conditions is examined in detail. The major project tasks were: airport sampling to define the characteristics of waste from deicing operations; testing of EG and PG degradation using laboratory-scale reactors and then by means of serum bottle tests; operation of an anaerobic fluidized bed reactor (AFBR); and analysis of the energy aspects of anaerobic processes with cost comparisons to traditional aerobic processes.

  12. 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

  13. Anaerobic and aerobic transformation of TNT

    SciTech Connect

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

    1996-12-31

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

  14. Fertilization stimulates anaerobic fuel degradation of antarctic soils by denitrifying microorganisms.

    PubMed

    Powell, Shane M; Ferguson, Susan H; Snape, Ian; Siciliano, Steven D

    2006-03-15

    Human activities in the Antarctic have resulted in hydrocarbon contamination of these fragile polar soils. Bioremediation is one of the options for remediation of these sites. However, little is known about anaerobic hydrocarbon degradation in polar soils and the influence of bioremediation practices on these processes. Using a field trial at Old Casey Station, Antarctica, we assessed the influence of fertilization on the anaerobic degradation of a 20-year old fuel spill. Fertilization increased hydrocarbon degradation in both anaerobic and aerobic soils when compared to controls, but was of most benefit for anaerobic soils where evaporation was negligible. This increased biodegradation in the anaerobic soils corresponded with a shift in the denitrifier community composition and an increased abundance of denitrifiers and benzoyl-CoA reductase. A microcosm study using toluene and hexadecane confirmed the degradative capacity within these soils under anaerobic conditions. It was observed that fertilized anaerobic soil degraded more of this hydrocarbon spike when incubated anaerobically than when incubated aerobically. We conclude that denitrifiers are actively involved in hydrocarbon degradation in Antarctic soils and that fertilization is an effective means of stimulating their activity. Further, when communities stimulated to degrade hydrocarbons under anaerobic conditions are exposed to oxygen, hydrocarbon degradation is suppressed. The commonly accepted belief that remediation of polar soils requires aeration needs to be reevaluated in light of this new data.

  15. 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.

  16. 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)

  17. 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?

  18. 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)

  19. 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.

  20. Mesophilic and thermophilic anaerobic digestion of biologically pretreated abattoir wastewaters in an upflow anaerobic filter.

    PubMed

    Gannoun, H; Bouallagui, H; Okbi, A; Sayadi, S; Hamdi, M

    2009-10-15

    The hydrolysis pretreatment of abattoir wastewaters (AW), rich in organic suspended solids (fats and protein) was studied in static and stirred batch reactors without aeration in the presence of natural microbial population acclimated in a storage tank of AW. Microbial analysis showed that the major populations which contribute to the pretreatment of AW belong to the genera Bacillus. Contrary to the static pretreatment, the stirred conditions favoured the hydrolysis and solubilization of 80% of suspended matter into soluble pollution. The pretreated AW, in continuous stirred tank reactor (CSTR) at a hydraulic retention time (HRT) of 2 days, was fed to an upflow anaerobic filter (UAF) at an HRT of 2 days. The performance of anaerobic digestion of biologically pretreated AW was examined under mesophilic (37 degrees C) and thermophilic (55 degrees C) conditions. The shifting from a mesophilic to a thermophilic environment in the UAF was carried out with a short start-up of thermophilic condition. The UAF ran at organic loading rates (OLRs) ranging from 0.9 to 6g COD/Ld in mesophilic conditions and at OLRs from 0.9 to 9 g COD/Ld in thermophilic conditions. COD removal efficiencies of 80-90% were achieved for OLRs up to 4.5 g COD/Ld in mesophilic conditions, while the highest OLRs i.e. 9 g COD/Ld led to efficiencies of 70-72% in thermophilic conditions. The biogas yield in thermophilic conditions was about 0.32-0.45 L biogas/g of COD removed for OLRs up to 4.5 g COD/Ld. For similar OLR, the UAF in mesophilic conditions showed lower percentage of methanization. Mesophilic anaerobic digestion has been shown to destroy pathogens partially, whereas the thermophilic process was more efficient in the removal of indicator microorganisms and pathogenic bacteria at different organic loading rates.

  1. 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.

  2. Anaerobic waste digestion in Germany--status and recent developments.

    PubMed

    Weiland, P

    2000-01-01

    Anaerobic treatment processes are especially suited for the utilization of wet organic wastes from agriculture and industry as well as for the organic part of source-separated household wastes. Anaerobic degradation is a very cost-effective method for treating biogenic wastes because the formed biogas can be used for heat and electricity production and the digester residues can be recycled to agriculture as a secondary fertilizer. Anaerobic technology will also be used for the common treatment of wastes together with renewable energy crops in order to reduce the CO2-emissions according the Kyoto protocol. Various process types are applied in Germany which differ in material, reaction conditions and in the form of the used reactor systems. The widespread introduction of anaerobic digestion in Germany has shown that biogenic organic wastes are a valuable source for energy and nutrients. Anaerobic waste treatment is done today in approx. 850 biogas plants on small farm scale as well as on large industrial scale with the best beneficial and economic outcome. Due to some new environmental protection acts which promote the recycling of wastes and their utilization for renewable energy formation it can be expected that several hundreds new biogas plants will be built per year in Germany. In order to use the synergetic effects of a combined fermentation of wastes and energy crops new process types must be developed in order to optimize the substrate combinations and the process conditions for maximum biodegradation.

  3. Prevailing Torque Locking Feature in Threaded Fasteners Using Anaerobic Adhesive

    NASA Technical Reports Server (NTRS)

    Hernandez, Alan; Hess, Daniel P.

    2016-01-01

    This paper presents results from tests to assess the use of anaerobic adhesive for providing a prevailing torque locking feature in threaded fasteners. Test procedures are developed and tests are performed on three fastener materials, four anaerobic adhesives, and both unseated assembly conditions. Five to ten samples are tested for each combination. Tests for initial use, reuse without additional adhesive, and reuse with additional adhesive are performed for all samples. A 48-hour cure time was used for all initial use and reuse tests. Test data are presented as removal torque versus removal angle with the specification required prevailing torque range added for performance assessment. Percent specification pass rates for the all combinations of fastener material, adhesive, and assembly condition are tabulated and reveal use of anaerobic adhesive as a prevailing torque locking feature is viable. Although not every possible fastener material and anaerobic adhesive combination provides prevailing torque values within specification, any combination can be assessed using the test procedures presented. Reuse without additional anaerobic adhesive generally provides some prevailing torque, and in some cases within specification. Reuse with additional adhesive often provides comparable removal torque data as in initial use.

  4. Anaerobic growth of Corynebacterium glutamicum via mixed-acid fermentation.

    PubMed

    Michel, Andrea; Koch-Koerfges, Abigail; Krumbach, Karin; Brocker, Melanie; Bott, Michael

    2015-11-01

    Corynebacterium glutamicum, a model organism in microbial biotechnology, is known to metabolize glucose under oxygen-deprived conditions to l-lactate, succinate, and acetate without significant growth. This property is exploited for efficient production of lactate and succinate. Our detailed analysis revealed that marginal growth takes place under anaerobic conditions with glucose, fructose, sucrose, or ribose as a carbon and energy source but not with gluconate, pyruvate, lactate, propionate, or acetate. Supplementation of glucose minimal medium with tryptone strongly enhanced growth up to a final optical density at 600 nm (OD600) of 12, whereas tryptone alone did not allow growth. Amino acids with a high ATP demand for biosynthesis and amino acids of the glutamate family were particularly important for growth stimulation, indicating ATP limitation and a restricted carbon flux into the oxidative tricarboxylic acid cycle toward 2-oxoglutarate. Anaerobic cultivation in a bioreactor with constant nitrogen flushing disclosed that CO2 is required to achieve maximal growth and that the pH tolerance is reduced compared to that under aerobic conditions, reflecting a decreased capability for pH homeostasis. Continued growth under anaerobic conditions indicated the absence of an oxygen-requiring reaction that is essential for biomass formation. The results provide an improved understanding of the physiology of C. glutamicum under anaerobic conditions. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  5. Anaerobic Growth of Corynebacterium glutamicum via Mixed-Acid Fermentation

    PubMed Central

    Michel, Andrea; Koch-Koerfges, Abigail; Krumbach, Karin; Brocker, Melanie

    2015-01-01

    Corynebacterium glutamicum, a model organism in microbial biotechnology, is known to metabolize glucose under oxygen-deprived conditions to l-lactate, succinate, and acetate without significant growth. This property is exploited for efficient production of lactate and succinate. Our detailed analysis revealed that marginal growth takes place under anaerobic conditions with glucose, fructose, sucrose, or ribose as a carbon and energy source but not with gluconate, pyruvate, lactate, propionate, or acetate. Supplementation of glucose minimal medium with tryptone strongly enhanced growth up to a final optical density at 600 nm (OD600) of 12, whereas tryptone alone did not allow growth. Amino acids with a high ATP demand for biosynthesis and amino acids of the glutamate family were particularly important for growth stimulation, indicating ATP limitation and a restricted carbon flux into the oxidative tricarboxylic acid cycle toward 2-oxoglutarate. Anaerobic cultivation in a bioreactor with constant nitrogen flushing disclosed that CO2 is required to achieve maximal growth and that the pH tolerance is reduced compared to that under aerobic conditions, reflecting a decreased capability for pH homeostasis. Continued growth under anaerobic conditions indicated the absence of an oxygen-requiring reaction that is essential for biomass formation. The results provide an improved understanding of the physiology of C. glutamicum under anaerobic conditions. PMID:26276118

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

    USGS Publications Warehouse

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

    1996-01-01

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

  7. Anaerobic Biodegradation of soybean biodiesel and diesel ...

    EPA Pesticide Factsheets

    Biotransformation of soybean biodiesel and its biodiesel/petrodiesel blends were investigated under sulfate-reducing conditions. Three blends of biodiesel, B100, B50, and B0, were treated using microbial cultures pre-acclimated to B100 (biodiesel only) and B80 (80% biodiesel and 20% petrodiesel). Results indicate that the biodiesel could be effectively biodegraded in the presence or absence of petrodiesel, whereas petrodiesel could not be biodegraded at all under sulfate-reducing conditions. The kinetics of biodegradation of individual Fatty Acid Methyl Ester (FAME) compounds and their accompanying sulfate-reduction rates were studied using a serum bottle test. As for the biodegradation of individual FAME compounds, the biodegradation rates for the saturated FAMEs decreased with increasing carbon chain length. For unsaturated FAMEs, biodegradation rates increased with increasing number of double bonds. The presence of petrodiesel had a greater effect on the rate of biodegradation of biodiesel than on the extent of removal. The objective of this study was to investigate anaerobic biodegradation of soybean biodiesel and petrodiesel blends in a sulfate-reducing environment, which is a prevalent condition in anaerobic sediments.

  8. Biochemical Mechanisms and Microorganisms Involved in Anaerobic Testosterone Metabolism in Estuarine Sediments

    PubMed Central

    Shih, Chao-Jen; Chen, Yi-Lung; Wang, Chia-Hsiang; Wei, Sean T.-S.; Lin, I-Ting; Ismail, Wael A.; Chiang, Yin-Ru

    2017-01-01

    Current knowledge on the biochemical mechanisms underlying microbial steroid metabolism in anaerobic ecosystems is extremely limited. Sulfate, nitrate, and iron [Fe (III)] are common electron acceptors for anaerobes in estuarine sediments. Here, we investigated anaerobic testosterone metabolism in anaerobic sediments collected from the estuary of Tamsui River, Taiwan. The anaerobic sediment samples were spiked with testosterone (1 mM) and individual electron acceptors (10 mM), including nitrate, Fe3+, and sulfate. The analysis of androgen metabolites indicated that testosterone biodegradation under denitrifying conditions proceeds through the 2,3-seco pathway, whereas testosterone biodegradation under iron-reducing conditions may proceed through an unidentified alternative pathway. Metagenomic analysis and PCR-based functional assays suggested that Thauera spp. were the major testosterone degraders in estuarine sediment samples incubated with testosterone and nitrate. Thauera sp. strain GDN1, a testosterone-degrading betaproteobacterium, was isolated from the denitrifying sediment sample. This strain tolerates a broad range of salinity (0–30 ppt). Although testosterone biodegradation did not occur under sulfate-reducing conditions, we observed the anaerobic biotransformation of testosterone to estrogens in some testosterone-spiked sediment samples. This is unprecedented since biotransformation of androgens to estrogens is known to occur only under oxic conditions. Our metagenomic analysis suggested that Clostridium spp. might play a role in this anaerobic biotransformation. These results expand our understanding of microbial metabolism of steroids under strictly anoxic conditions. PMID:28848528

  9. 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.

  10. 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.

  11. Fate of estradiol and testosterone in anaerobic lagoon digestors

    USDA-ARS?s Scientific Manuscript database

    Laboratory-scale lagoon digestors were constructed, and the fate of 14C-labelled 17ß-estradiol (E2) and testosterone (Test) were monitored for 42 d anaerobically under biological and sterile conditions. Hormone levels decreased in the liquid layer and increased in the sludge with time. At 42 d, 16-2...

  12. Apparent posttranscriptional block to anaerobic induction of endogenous leukemia virus.

    PubMed Central

    Whitaker-Dowling, P A; Marotti, K R; Anderson, G R

    1979-01-01

    Uninfected Fischer rat cells were induced by anaerobic stress to transcribe high levels of endogenous type C leukemia virus RNA. Complete 35S virus RNA with attached polyadenylic acid sequences was found associated with polysomes, indicating functional mRNA. Since no mature virus was released under these conditions, the presence of a posttranscriptional block to complete virus synthesis is strongly indicated. PMID:232174

  13. Anaerobic Soil Disinfestation For Florida Specialty Crop Production

    USDA-ARS?s Scientific Manuscript database

    Anaerobic soil disinfestation (ASD) is a process in which organic amendments are applied to soil, covered with a polyethylene film, and saturated with water to create conditions conducive for soil bacteria to deplete oxygen levels and generate organic acids in soil. The generation of acids and re...

  14. Biogas production from anaerobic digestion of Spirulina maxima algal biomass

    SciTech Connect

    Rejean Samson; Anh LeDuy

    1982-08-01

    Spirulina maxima algal biomass could be used as the sole nutrient for the production of biogas by anaerobic digestion process. It is relatively simple to adapt the municipal sewage sludge to this new substrate. The adapted sludge is very stable. Under nonoptimal conditions, the methane yield and productivity obtained were 0.26 m/sup 3//(kg VS added day) and 0.26 m/sup 3//(kg VS added day), respectively, with the semicontinuous, daily fed, anaerobic digestion having loading rate of 0.97 kg VS/(m/sup 3/ day), retention time of 33 days and temperature of 30/sup 0/C.

  15. Dynamics and genetic diversification of Escherichia coli during experimental adaptation to an anaerobic environment.

    PubMed

    Finn, Thomas J; Shewaramani, Sonal; Leahy, Sinead C; Janssen, Peter H; Moon, Christina D

    2017-01-01

    Many bacteria are facultative anaerobes, and can proliferate in both anoxic and oxic environments. Under anaerobic conditions, fermentation is the primary means of energy generation in contrast to respiration. Furthermore, the rates and spectra of spontaneous mutations that arise during anaerobic growth differ to those under aerobic growth. A long-term selection experiment was undertaken to investigate the genetic changes that underpin how the facultative anaerobe, Escherichia coli, adapts to anaerobic environments. Twenty-one populations of E. coli REL4536, an aerobically evolved 10,000th generation descendent of the E. coli B strain, REL606, were established from a clonal ancestral culture. These were serially sub-cultured for 2,000 generations in a defined minimal glucose medium in strict aerobic and strict anaerobic environments, as well as in a treatment that fluctuated between the two environments. The competitive fitness of the evolving lineages was assessed at approximately 0, 1,000 and 2,000 generations, in both the environment of selection and the alternative environment. Whole genome re-sequencing was performed on random colonies from all lineages after 2,000-generations. Mutations were identified relative to the ancestral genome, and based on the extent of parallelism, traits that were likely to have contributed towards adaptation were inferred. There were increases in fitness relative to the ancestor among anaerobically evolved lineages when tested in the anaerobic environment, but no increases were found in the aerobic environment. For lineages that had evolved under the fluctuating regime, relative fitness increased significantly in the anaerobic environment, but did not increase in the aerobic environment. The aerobically-evolved lineages did not increase in fitness when tested in either the aerobic or anaerobic environments. The strictly anaerobic lineages adapted more rapidly to the anaerobic environment than did the fluctuating lineages. Two main

  16. Anaerobic α-amylase production and secretion with fumarate as the final electron acceptor in Saccharomyces cerevisiae.

    PubMed

    Liu, Zihe; Österlund, Tobias; Hou, Jin; Petranovic, Dina; Nielsen, Jens

    2013-05-01

    In this study, we focus on production of heterologous α-amylase in the yeast Saccharomyces cerevisiae under anaerobic conditions. We compare the metabolic fluxes and transcriptional regulation under aerobic and anaerobic conditions, with the objective of identifying the final electron acceptor for protein folding under anaerobic conditions. We find that yeast produces more amylase under anaerobic conditions than under aerobic conditions, and we propose a model for electron transfer under anaerobic conditions. According to our model, during protein folding the electrons from the endoplasmic reticulum are transferred to fumarate as the final electron acceptor. This model is supported by findings that the addition of fumarate under anaerobic (but not aerobic) conditions improves cell growth, specifically in the α-amylase-producing strain, in which it is not used as a carbon source. Our results provide a model for the molecular mechanism of anaerobic protein secretion using fumarate as the final electron acceptor, which may allow for further engineering of yeast for improved protein secretion under anaerobic growth conditions.

  17. Performance of an anaerobic membrane bioreactor for pharmaceutical wastewater treatment.

    PubMed

    Svojitka, Jan; Dvořák, Lukáš; Studer, Martin; Straub, Jürg Oliver; Frömelt, Heinz; Wintgens, Thomas

    2017-04-01

    Anaerobic treatment of wastewater and waste organic solvents originating from the pharmaceutical and chemical industries was tested in a pilot anaerobic membrane bioreactor, which was operated for 580days under different operational conditions. The goal was to test the long-term treatment efficiency and identify inhibitory factors. The highest COD removal of up to 97% was observed when the influent concentration was increased by the addition of methanol (up to 25gL(-1) as COD). Varying and generally lower COD removal efficiency (around 78%) was observed when the anaerobic membrane bioreactor was operated with incoming pharmaceutical wastewater as sole carbon source. The addition of waste organic solvents (>2.5gL(-1) as COD) to the influent led to low COD removal efficiency or even to the breakdown of anaerobic digestion. Changes in the anaerobic population (e.g., proliferation of the genus Methanosarcina) resulting from the composition of influent were observed. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Potential nanosilver impact on anaerobic digestion at moderate silver concentrations.

    PubMed

    Yang, Yu; Chen, Qian; Wall, Judy D; Hu, Zhiqiang

    2012-03-15

    Silver nanoparticles (AgNPs, nanosilver) entering the sewers and wastewater treatment plants (WWTPs) are mostly accumulated in the sludge. In this study, we determined the impact of AgNPs on anaerobic glucose degradation, sludge digestion and methanogenic assemblages. At ambient (22 °C) and mesophilic temperatures (37 °C), there was no significant difference in biogas and methane production between the sludge treated with AgNPs at the concentrations up to 40 mg Ag/L (13.2 g silver/Kg biomass COD) and the control. In these anaerobic digestion samples, acetate and propionic acid were the only detectable volatile fatty acids (VFAs) and they were depleted in 3 days. On the other hand, more than 90% of AgNPs was removed from the liquid phase and associated with the sludge while almost no silver ions were released from AgNPs under anaerobic conditions. Quantitative PCR results indicated that Methanosaeta and Methanomicrobiales were the dominant methanogens, and the methanogenic diversity and population remained largely unchanged after nanosilver exposure and anaerobic digestion. The results suggest that AgNPs at moderate concentrations (e.g., ≤40 mg/L) have negligible impact on anaerobic digestion and methanogenic assemblages because of little to no silver ion release.

  19. 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.

  20. Model selection, identification and validation in anaerobic digestion: a review.

    PubMed

    Donoso-Bravo, Andres; Mailier, Johan; Martin, Cristina; Rodríguez, Jorge; Aceves-Lara, César Arturo; Vande Wouwer, Alain

    2011-11-01

    Anaerobic digestion enables waste (water) treatment and energy production in the form of biogas. The successful implementation of this process has lead to an increasing interest worldwide. However, anaerobic digestion is a complex biological process, where hundreds of microbial populations are involved, and whose start-up and operation are delicate issues. In order to better understand the process dynamics and to optimize the operating conditions, the availability of dynamic models is of paramount importance. Such models have to be inferred from prior knowledge and experimental data collected from real plants. Modeling and parameter identification are vast subjects, offering a realm of approaches and methods, which can be difficult to fully understand by scientists and engineers dedicated to the plant operation and improvements. This review article discusses existing modeling frameworks and methodologies for parameter estimation and model validation in the field of anaerobic digestion processes. The point of view is pragmatic, intentionally focusing on simple but efficient methods.

  1. 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.

  2. 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)

  3. 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)

  4. Anaerobic biodegradation of hexazinone in four sediments.

    PubMed

    Wang, Huili; Xu, Shuxia; Tan, Chengxia; Wang, Xuedong

    2009-05-30

    Anaerobic biodegradation of hexazinone was investigated in four sediments (L1, L2, Y1 and Y2). Results showed that the L2 sediment had the highest biodegradation potential among four sediments. However, the Y1 and Y2 sediments had no capacity to biodegrade hexazinone. Sediments with rich total organic carbon, long-term contamination history by hexazinone and neutral pH may have a high biodegradation potential because the former two factors can induce the growth of microorganisms responsible for biodegradation and the third factor can offer suitable conditions for biodegradation. The addition of sulfate or nitrate as electron acceptors enhanced hexazinone degradation. As expected, the addition of electron donors (lactate, acetate or pyruvate) substantially inhibited the degradation. In natural environmental conditions, the effect of intermediate A [3-(4-hydroxycyclohexyl)-6-(dimethylamino)-1-methyl-1,3,5-triazine-2,4(1H, 3H)dione] on anaerobic hexazinone degradation was negligible because of its low level.

  5. 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

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

    PubMed

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

    2016-06-01

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

  7. 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

  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. Anaerobic Biotransformation and Mobility of Pu and Pu-EDTA

    SciTech Connect

    Bolton, H., Jr.; Bailey, V.L.; Plymale, A.E.; Rai, D.; Xun, L.

    2006-04-05

    The complexation of radionuclides (e.g., plutonium (Pu) and {sup 60}Co) by co-disposed ethylenediaminetetraacetate (EDTA) has enhanced their transport in sediments at DOE sites. Pu(IV)-EDTA is not stable in the presence of relatively soluble Fe(III) compounds. Since most DOE sites have Fe(III) containing sediments, Pu(IV) is likely not the mobile form of Pu-EDTA. The only other Pu-EDTA complex stable in groundwater relevant to DOE sites would be Pu(III)-EDTA, which only forms under anaerobic conditions. Research is therefore needed to investigate the biotransformation of Pu and Pu-EDTA under anaerobic conditions and the anaerobic biodegradation of Pu-EDTA. The biotransformation of Pu and Pu-EDTA under various anaerobic regimes is poorly understood including the reduction kinetics of Pu(IV) to Pu(III) from soluble (Pu(IV)-EDTA) and insoluble Pu(IV), the redox conditions required for this reduction, the strength of the Pu(III)-EDTA, how the Pu(III)-EDTA competes with other dominant anoxic soluble metals (e.g., Fe(II)), and the oxidation kinetics of Pu(III)-EDTA. Finally, soluble Pu(III)-EDTA under anaerobic conditions would require anaerobic degradation of the EDTA to limit Pu(III) transport. Anaerobic EDTA degrading microorganisms have never been isolated. Recent results have shown that Shewanella oneidensis MR-1, a dissimilatory metal reducing bacterium, can reduce Pu(IV) to Pu(III). The Pu(IV) was provided as insoluble PuO2. The highest rate of Pu(IV) reduction was with the addition of AQDS, an electron shuttle. Of the total amount of Pu solubilized (i.e., soluble through a 0.36 nm filter), approximately 70% was Pu(III). The amount of soluble Pu was between 4.8 and 3.2 micromolar at day 1 and 6, respectively, indicating rapid reduction. The micromolar Pu is significant since the drinking water limit for Pu is 10{sup -12} M. On-going experiments are investigating the influence of EDTA on the rate of Pu reduction and the stability of the formed Pu(III). We have also

  11. INT-dehydrogenase activity test for assessing anaerobic biodegradability of organic compounds.

    PubMed

    Hongwei, Yang; Zhanpeng, Jiang; Shaoqi, Shi; Tang, W Z

    2002-11-01

    This study assessed anaerobic biodegradability of organic compounds from microorganism activity. Dehydrogenase activity can be a good parameter characterizing the microorganism activity. A modified method of 2-(p-iodophenyl-3-(p-nitrophenyl)-5-pheny tetrazolium chloride-dehydrogenase activity determination was proposed in anaerobic biodegradability assessment. Cubic spline curves were adopted to link the data points. This curve was integrated twice to calculate areas. The microorganism activity index in anaerobic biodegradability assessment was calculated by standardizing the integral. According to the results of the activity index, 14 kinds of organic compounds were classified into readily, partially, and poorly biodegradable under anaerobic conditions, respectively. As a result, some conclusions for anaerobic biodegradability of organic compounds were reached, based on the activity index value.

  12. Treatment of packaging board whitewater in anaerobic/aerobic biokidney.

    PubMed

    Alexandersson, T; Malmqvist, A

    2005-01-01

    Whitewater from production of packaging board was treated in a combined anaerobic/aerobic biokidney, both in laboratory scale and pilot plant experiments. Both the laboratory experiments and the pilot plant trial demonstrate that a combined anaerobic/aerobic process is suitable for treating whitewater from a packaging mill. It is also possible to operate the process at the prevailing whitewater temperature. In the laboratory under mesophilic conditions the maximal organic load was 12 kg COD/m3*d on the anaerobic reactor and 6.7 kg COD/m3*d on the aerobic reactor. This gave a hydraulic retention time, HRT, in the anaerobic reactor of 10 hours and 2 hours in the aerobic reactor. The reduction of COD was between 85 and 90% after the first stage and the total reduction was between 88 to 93%. Under thermophilic conditions in the laboratory the organic load was slightly lower than 9.6 COD/m3*d and between 10 and 16 COD/m3*d, respectively. The HRT was 16.5 and 3.4 hours and the removal was around 75% after the anaerobic reactor and 87% after the total process. For the pilot plant experiment at a mill the HRT in the anaerobic step varied between 3 and 17 hours and the corresponding organic load between 4 and 44 kg COD/m3*d. The HRT in the aerobic step varied between 1 and 6 hours and the organic load between 1.5 and 26 kg COD/m3*d. The removal of soluble organic matter was 78% in the anaerobic step and 86% after the combined treatment at the lowest loading level. The removal efficiency at the highest loading level was about 65% in the anaerobic step and 77% after the aerobic step. In the pilot plant trial the removal efficiency was not markedly affected by the variations in whitewater composition that were caused by change of production. The variations, however, made the manual control of the nutrient dosage inadequate and resulted in large variations in effluent nutrient concentration. This demonstrates the need for an automatic nutrient dosage system. The first step

  13. Anaerobic Metabolism: Linkages to Trace Gases and Aerobic Processes

    NASA Astrophysics Data System (ADS)

    Megonigal, J. P.; Hines, M. E.; Visscher, P. T.

    2003-12-01

    Life evolved and flourished in the absence of molecular oxygen (O2). As the O2 content of the atmosphere rose to the present level of 21% beginning about two billion years ago, anaerobic metabolism was gradually supplanted by aerobic metabolism. Anaerobic environments have persisted on Earth despite the transformation to an oxidized state because of the combined influence of water and organic matter. Molecular oxygen diffuses about 104 times more slowly through water than air, and organic matter supports a large biotic O2 demand that consumes the supply faster than it is replaced by diffusion. Such conditions exist in wetlands, rivers, estuaries, coastal marine sediments, aquifers, anoxic water columns, sewage digesters, landfills, the intestinal tracts of animals, and the rumen of herbivores. Anaerobic microsites are also embedded in oxic environments such as upland soils and marine water columns. Appreciable rates of aerobic respiration are restricted to areas that are in direct contact with air or those inhabited by organisms that produce O2.Rising atmospheric O2 reduced the global area of anaerobic habitat, but enhanced the overall rate of anaerobic metabolism (at least on an area basis) by increasing the supply of electron donors and acceptors. Organic carbon production increased dramatically, as did oxidized forms of nitrogen, manganese, iron, sulfur, and many other elements. In contemporary anaerobic ecosystems, nearly all of the reducing power is derived from photosynthesis, and most of it eventually returns to O2, the most electronegative electron acceptor that is abundant. This photosynthetically driven redox gradient has been thoroughly exploited by aerobic and anaerobic microorganisms for metabolism. The same is true of hydrothermal vents (Tunnicliffe, 1992) and some deep subsurface environments ( Chapelle et al., 2002), where thermal energy is the ultimate source of the reducing power.Although anaerobic habitats are currently a small fraction of Earth

  14. Antibiotic Susceptibility Pattern of Aerobic and Anaerobic Bacteria Isolated From Surgical Site Infection of Hospitalized Patients

    PubMed Central

    Akhi, Mohammad Taghi; Ghotaslou, Reza; Beheshtirouy, Samad; Asgharzadeh, Mohammad; Pirzadeh, Tahereh; Asghari, Babak; Alizadeh, Naser; Toloue Ostadgavahi, Ali; Sorayaei Somesaraei, Vida; Memar, Mohammad Yousef

    2015-01-01

    Background: Surgical Site Infections (SSIs) are infections of incision or deep tissue at operation sites. These infections prolong hospitalization, delay wound healing, and increase the overall cost and morbidity. Objectives: This study aimed to investigate anaerobic and aerobic bacteria prevalence in surgical site infections and determinate antibiotic susceptibility pattern in these isolates. Materials and Methods: One hundred SSIs specimens were obtained by needle aspiration from purulent material in depth of infected site. These specimens were cultured and incubated in both aerobic and anaerobic condition. For detection of antibiotic susceptibility pattern in aerobic and anaerobic bacteria, we used disk diffusion, agar dilution, and E-test methods. Results: A total of 194 bacterial strains were isolated from 100 samples of surgical sites. Predominant aerobic and facultative anaerobic bacteria isolated from these specimens were the members of Enterobacteriaceae family (66, 34.03%) followed by Pseudomonas aeruginosa (26, 13.4%), Staphylococcus aureus (24, 12.37%), Acinetobacter spp. (18, 9.28%), Enterococcus spp. (16, 8.24%), coagulase negative Staphylococcus spp. (14, 7.22%) and nonhemolytic streptococci (2, 1.03%). Bacteroides fragilis (26, 13.4%), and Clostridium perfringens (2, 1.03%) were isolated as anaerobic bacteria. The most resistant bacteria among anaerobic isolates were B. fragilis. All Gram-positive isolates were susceptible to vancomycin and linezolid while most of Enterobacteriaceae showed sensitivity to imipenem. Conclusions: Most SSIs specimens were polymicrobial and predominant anaerobic isolate was B. fragilis. Isolated aerobic and anaerobic strains showed high level of resistance to antibiotics. PMID:26421133

  15. Inhibition of biogas production by alkyl benzene sulfonates (LAS) in a screening test for anaerobic biodegradability.

    PubMed

    Garcia, M Teresa; Campos, Encarna; Dalmau, Manel; Illán, Patricia; Sánchez-Leal, Joaquin

    2006-02-01

    The effect of the inoculum source on the digestion of linear alkylbenzene sulfonates (LAS) under anaerobic conditions has been investigated. The potential for primary and ultimate LAS biodegradation of anaerobic sludge samples obtained from wastewater treatment plants (WWTPs) of different geographical locations was studied applying a batch test system. It was found that only 4-22% of the LAS added to the batch anaerobic digesters was primarily transformed suggesting a poor primary degradation of the LAS molecule in anaerobic discontinuous systems. Regarding ultimate biodegradation, the addition of LAS to the batch anaerobic digesters caused a reduction on the extent of biogas production. Significant differences in the inhibition extent of the biogas production were observed (4-26%) depending on the sludge used as inoculum. Effect of the surfactant on the anaerobic microorganisms was correlated with its concentration in the aqueous phase. Sorption of LAS on anaerobic sludge affects its toxicity by depletion of the available fraction of the surfactant. LAS content on sludge was related to the total amount of calcium and magnesium extractable ions. The presence of divalent cations promote the association of LAS with anaerobic sludge reducing its bioavailability and the extent of its inhibitory effect on the biogas production.

  16. Sequential (anaerobic/aerobic) biological treatment of Dalaman SEKA pulp and paper industry effluent.

    PubMed

    Tezel, U; Guven, E; Erguder, T H; Demirer, G N

    2001-01-01

    In the pulp and paper industry, lignin and other color compounds are removed by chemical agents in bleaching process. Use of chlorine-based agents results in production of degradation products which include various chloro-organic derivatives. Since these new compounds are highly chlorinated, they cause a problem in the treatment of pulp and paper industry wastewaters. Chemical precipitation, lagooning, activated sludge, and anaerobic treatment are the processes used for treating pulp and paper effluents. Furthermore, a combination of these processes is also applicable. In this study, the effluent of Dalaman SEKA Pulp and Paper Industry was examined for its toxic effects on anaerobic microorganisms by anaerobic toxicity assay. Additionally, this wastewater was applied to a sequential biotreatment process consisting of an upflow anaerobic sludge blanket as the anaerobic stage and a once-through completely mixed stirred tank as the aerobic stage. Results indicated that: (1) Dalaman SEKA Pulp and Paper Industry wastewater exerted no inhibitory effects on the anaerobic cultures under the studied conditions, and (2) application of a sequential biological (anaerobic/aerobic) system to treat the Dalaman SEKA Pulp and Paper Industry wastewater resulted in approximately 91% COD and 58% AOX removals at a HRT of 5 and 6.54 h for anaerobic and aerobic, respectively.

  17. The strict anaerobe Bacteroides fragilis grows in and benefits from nanomolar concentrations of oxygen.

    PubMed

    Baughn, Anthony D; Malamy, Michael H

    2004-01-29

    Strict anaerobes cannot grow in the presence of greater than 5 micro M dissolved oxygen. Despite this growth inhibition, many strict anaerobes of the Bacteroides class of eubacteria can survive in oxygenated environments until the partial pressure of O2 (PO2) is sufficiently reduced. For example, the periodontal pathogens Porphyromonas gingivalis and Tannerella forsythensis colonize subgingival plaques of mammals, whereas several other Bacteroides species colonize the gastrointestinal tract of animals. It has been suggested that pre-colonization of these sites by facultative anaerobes is essential for reduction of the PO2 and subsequent colonization by strict anaerobes. However, this model is inconsistent with the observation that Bacteroides fragilis can colonize the colon in the absence of facultative anaerobes. Thus, this strict anaerobe may have a role in reduction of the environmental PO2. Although some strictly anaerobic bacteria can consume oxygen through an integral membrane electron transport system, the physiological role of this system has not been established in these organisms. Here we demonstrate that B. fragilis encodes a cytochrome bd oxidase that is essential for O2 consumption and is required, under some conditions, for the stimulation of growth in the presence of nanomolar concentrations of O2. Furthermore, our data suggest that this property is conserved in many other organisms that have been described as strict anaerobes.

  18. Natural attenuation of xenobiotic compounds: Anaerobic field injection experiment

    SciTech Connect

    Ruegge, K.; Bjerg, P.L.; Mosbaek, H.; Christensen, T.H.

    1995-12-31

    Currently, a continuous field injection experiment is being performed in the anaerobic part of a pollution plume downgradient of the Grindsted Landfill in Denmark. This natural gradient experiment includes an injection of 18 different xenobiotic compounds with bromide as a tracer. The injection is taking place under methanogenic/sulfate-reducing conditions and the compounds will, as they migrate with the groundwater, pass through a zone where the redox conditions have been determined as iron-reducing.

  19. The aerobic activity of metronidazole against anaerobic bacteria.

    PubMed

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

    2015-05-01

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

  20. Potential Application of Anaerobic Extremophiles for Hydrogen Production

    NASA Technical Reports Server (NTRS)

    Pikuta, Elena V.; Hoover, Richard B.

    2004-01-01

    During substrate fermentation many anaerobes produce the hydrogen as a waste product, which often regulates the growth of the cultures as an inhibitor. In nature the hydrogen is usually removed from the ecosystem due to its physical properties or by consumption of hydrogen by secondary anaerobes, which sometimes behave as competitors for electron donors as is seen in the classical example in anaerobic microbial communities via the interaction between methanogens and sulfate- or sulfur- reducers. It was demonstrated previously on mixed cultures of anaerobes at neutral pH that bacterial hydrogen production could provide an alternative energy source. But at neutral pH the original cultures can easily be contaminated by methanogens, a most unpleasant side effect of these conditions is the development of pathogenic bacteria. In both cases the rate of hydrogen production was dramatically decreased since some part of the hydrogen was transformed to methane, and the cultivation of human pathogens on a global scale is very dangerous. In our laboratory, experiments with obligately alkaliphilic bacteria that excrete hydrogen as the end metabolic product were performed at different temperature regimes. Mesophilic and moderately thermophilic bacterial cultures have been studied and compared for the most effective hydrogen production. For high-mineralized media with pH 9.5-10.0 not many methanogens are known to exist. Furthermore, the development of pathogenic contaminant microorganisms is virtually impossible: carbonate-saturated solutions are used as antiseptics in medicine. Therefore the cultivation of alkaliphilic hydrogen producing bacteria could be considered as most safe process for global Scale industry in future. Here we present experimental data on the rates of hydrogen productivity for mesophilic, alkaliphilic, obligately anaerobic bacterium Spirocheta americana ASpG1 and moderately thermophilic, alkaliphilic, facultative anaerobe Anoxybacillus pushchinoensis K1 and

  1. Potential Application of Anaerobic Extremophiles for Hydrogen Production

    NASA Technical Reports Server (NTRS)

    Pikuta, Elena V.; Hoover, Richard B.

    2004-01-01

    During substrate fermentation many anaerobes produce the hydrogen as a waste product, which often regulates the growth of the cultures as an inhibitor. In nature the hydrogen is usually removed from the ecosystem due to its physical properties or by consumption of hydrogen by secondary anaerobes, which sometimes behave as competitors for electron donors as is seen in the classical example in anaerobic microbial communities via the interaction between methanogens and sulfate- or sulfur- reducers. It was demonstrated previously on mixed cultures of anaerobes at neutral pH that bacterial hydrogen production could provide an alternative energy source. But at neutral pH the original cultures can easily be contaminated by methanogens, a most unpleasant side effect of these conditions is the development of pathogenic bacteria. In both cases the rate of hydrogen production was dramatically decreased since some part of the hydrogen was transformed to methane, and the cultivation of human pathogens on a global scale is very dangerous. In our laboratory, experiments with obligately alkaliphilic bacteria that excrete hydrogen as the end metabolic product were performed at different temperature regimes. Mesophilic and moderately thermophilic bacterial cultures have been studied and compared for the most effective hydrogen production. For high-mineralized media with pH 9.5-10.0 not many methanogens are known to exist. Furthermore, the development of pathogenic contaminant microorganisms is virtually impossible: carbonate-saturated solutions are used as antiseptics in medicine. Therefore the cultivation of alkaliphilic hydrogen producing bacteria could be considered as most safe process for global Scale industry in future. Here we present experimental data on the rates of hydrogen productivity for mesophilic, alkaliphilic, obligately anaerobic bacterium Spirocheta americana ASpG1 and moderately thermophilic, alkaliphilic, facultative anaerobe Anoxybacillus pushchinoensis K1 and

  2. Adaptation and Antibiotic Tolerance of Anaerobic Burkholderia pseudomallei ▿ †

    PubMed Central

    Hamad, Mohamad A.; Austin, Chad R.; Stewart, Amanda L.; Higgins, Mike; Vázquez-Torres, Andrés; Voskuil, Martin I.

    2011-01-01

    The Gram-negative bacterium Burkholderia pseudomallei is the etiological agent of melioidosis and is remarkably resistant to most classes of antibacterials. Even after months of treatment with antibacterials that are relatively effective in vitro, there is a high rate of treatment failure, indicating that this pathogen alters its patterns of antibacterial susceptibility in response to cues encountered in the host. The pathology of melioidosis indicates that B. pseudomallei encounters host microenvironments that limit aerobic respiration, including the lack of oxygen found in abscesses and in the presence of nitric oxide produced by macrophages. We investigated whether B. pseudomallei could survive in a nonreplicating, oxygen-deprived state and determined if this physiological state was tolerant of conventional antibacterials. B. pseudomallei survived initial anaerobiosis, especially under moderately acidic conditions similar to those found in abscesses. Microarray expression profiling indicated a major shift in the physiological state of hypoxic B. pseudomallei, including induction of a variety of typical anaerobic-environment-responsive genes and genes that appear specific to anaerobic B. pseudomallei. Interestingly, anaerobic B. pseudomallei was unaffected by antibacterials typically used in therapy. However, it was exquisitely sensitive to drugs used against anaerobic pathogens. After several weeks of anaerobic culture, a significant loss of viability was observed. However, a stable subpopulation that maintained complete viability for at least 1 year was established. Thus, during the course of human infection, if a minor subpopulation of bacteria inhabited an oxygen-restricted environment, it might be indifferent to traditional therapy but susceptible to antibiotics frequently used to treat anaerobic infections. PMID:21537012

  3. Hydroponic system for the treatment of anaerobic liquid.

    PubMed

    Krishnasamy, K; Nair, J; Bäuml, B

    2012-01-01

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

  4. Anaerobic Toxicity of Cationic Silver Nanoparticles | Science ...

    EPA Pesticide Factsheets

    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 polyvinylpyrrolidone coated AgNPs (PVP-AgNps) and (3) positively charged branched polyethyleneimine coated AgNPs (BPEI-AgNPs). The AgNPs investigated in this experiment were similar in size (10-15 nm), spherical in shape, but varied in surface charge which ranged from highly negative to highly positive. While, at AgNPs concentrations lower than 5 mg L-1, the anaerobic decomposition process was not influenced by the presence of the nanoparticles, there was an observed impact on the diversity of the microbial community. At elevated concentrations (100 mg L-1 as silver), only the cationic BPEI-AgNPs demonstrated toxicity similar in magnitude to that of Ag+. Both citrate and PVP-AgNPs did not exhibit toxicity at the 100 mg L-1 as measured by biogas evolution. These findings further indicate the varying modes of action for nanoparticle toxicity and represent one of the few studies that evaluate end-of-life management concerns with regards to the increasing use of nanomaterials in our everyday life. These findings also highlight some of the concerns with a one size fits all approach to the evaluation of environmental health and safety concerns associated with the use of nanoparticles. The current

  5. Anaerobic Toxicity of Cationic Silver Nanoparticles | Science ...

    EPA Pesticide Factsheets

    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 polyvinylpyrrolidone coated AgNPs (PVP-AgNps) and (3) positively charged branched polyethyleneimine coated AgNPs (BPEI-AgNPs). The AgNPs investigated in this experiment were similar in size (10-15 nm), spherical in shape, but varied in surface charge which ranged from highly negative to highly positive. While, at AgNPs concentrations lower than 5 mg L-1, the anaerobic decomposition process was not influenced by the presence of the nanoparticles, there was an observed impact on the diversity of the microbial community. At elevated concentrations (100 mg L-1 as silver), only the cationic BPEI-AgNPs demonstrated toxicity similar in magnitude to that of Ag+. Both citrate and PVP-AgNPs did not exhibit toxicity at the 100 mg L-1 as measured by biogas evolution. These findings further indicate the varying modes of action for nanoparticle toxicity and represent one of the few studies that evaluate end-of-life management concerns with regards to the increasing use of nanomaterials in our everyday life. These findings also highlight some of the concerns with a one size fits all approach to the evaluation of environmental health and safety concerns associated with the use of nanoparticles. The current

  6. Electrolysis-enhanced anaerobic digestion of wastewater.

    PubMed

    Tartakovsky, B; Mehta, P; Bourque, J-S; Guiot, S R

    2011-05-01

    This study demonstrates enhanced methane production from wastewater in laboratory-scale anaerobic reactors equipped with electrodes for water electrolysis. The electrodes were installed in the reactor sludge bed and a voltage of 2.8-3.5 V was applied resulting in a continuous supply of oxygen and hydrogen. The oxygen created micro-aerobic conditions, which facilitated hydrolysis of synthetic wastewater and reduced the release of hydrogen sulfide to the biogas. A portion of the hydrogen produced electrolytically escaped to the biogas improving its combustion properties, while another part was converted to methane by hydrogenotrophic methanogens, increasing the net methane production. The presence of oxygen in the biogas was minimized by limiting the applied voltage. At a volumetric energy consumption of 0.2-0.3 Wh/L(R), successful treatment of both low and high strength synthetic wastewaters was demonstrated. Methane production was increased by 10-25% and reactor stability was improved in comparison to a conventional anaerobic reactor.

  7. Life at extreme limits: the anaerobic halophilic alkalithermophiles.

    PubMed

    Mesbah, Noha M; Wiegel, Juergen

    2008-03-01

    The ability of anaerobic microorganisms to proliferate under extreme conditions is of widespread importance for microbial physiology, remediation, industry, and evolution. The halophilic alkalithermophiles are a novel group of polyextremophiles. Tolerance to alkaline pH, elevated NaCl concentrations, and high temperatures necessitates mechanisms for cytoplasmic pH acidification; permeability control of the cell membrane; and stability of proteins, the cell wall, and other cellular constituents to multiple extreme conditions. Although it is generally assumed that extremophiles growing at more than one extreme combine adaptive mechanisms for each individual extreme, adaptations for individual extremes often counteract each other. However, in alkaline, hypersaline niches heated via intense solar irradiation, culture-independent analyses have revealed the presence of an extensive diversity of aerobic and anaerobic microorganisms belonging to Bacteria and Archaea that survive and grow under multiple harsh conditions. Thus, polyextremophiles must have developed novel adaptive strategies enabling them to grow and proliferate under multiple extreme conditions. The recent isolation of two novel anaerobic, halophilic alkalithermophiles, Natranaerobius thermophilus and Halonatronum saccharophilum, will provide a platform for detailed biochemical, genomic, and proteomic experiments, allowing a greater understanding of the novel adaptive mechanisms undoubtedly employed by polyextremophiles. In this review, we highlight growth characteristics, ecology, and phylogeny of the anaerobic halophilic alkalithermophiles isolated. We also describe the bioenergetic and physiological problems posed by growth at the multiple extreme conditions of alkaline pH, high NaCl concentration, and elevated temperature under anoxic conditions and highlight recent findings and unresolved problems regarding adaptation to multiple extreme conditions.

  8. 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.

  9. Anaerobic methanotrophy in tidal wetland: Effects of electron acceptors

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  10. Anaerobic and aerobic metabolism of diverse aromatic compounds by the photosynthetic bacterium Rhodopseudomonas palustris.

    PubMed Central

    Harwood, C S; Gibson, J

    1988-01-01

    The purple nonsulfur photosynthetic bacterium Rhodopseudomonas palustris used diverse aromatic compounds for growth under anaerobic and aerobic conditions. Many phenolic, dihydroxylated, and methoxylated aromatic acids, as well as aromatic aldehydes and hydroaromatic acids, supported growth of strain CGA001 in both the presence and absence of oxygen. Some compounds were metabolized under only aerobic or under only anaerobic conditions. Two other strains, CGC023 and CGD052, had similar anaerobic substrate utilization patterns, but CGD052 was able to use a slightly larger number of compounds for growth. These results show that R. palustris is far more versatile in terms of aromatic degradation than had been previously demonstrated. A mutant (CGA033) blocked in aerobic aromatic metabolism remained wild type with respect to anaerobic degradative abilities, indicating that separate metabolic pathways mediate aerobic and anaerobic breakdown of diverse aromatics. Another mutant (CGA047) was unable to grow anaerobically on either benzoate or 4-hydroxybenzoate, and these compounds accumulated in growth media when cells were grown on more complex aromatic compounds. This indicates that R. palustris has two major anaerobic routes for aromatic ring fission, one that passes through benzoate and one that passes through 4-hydroxybenzoate. Images PMID:3377491

  11. Anaerobic Biotransformation and Mobility of Pu and Pu-EDTA

    SciTech Connect

    Bolton, H., Jr.; Rai, D.; Xun, L.

    2005-04-18

    The complexation of radionuclides (e.g., plutonium (Pu) and {sup 60}Co) by codisposed ethylenediaminetetraacetate (EDTA) has enhanced their transport in sediments at DOE sites. Our previous NABIR research investigated the aerobic biodegradation and biogeochemistry of Pu(IV)-EDTA. Plutonium(IV) forms stable complexes with EDTA under aerobic conditions and an aerobic EDTA degrading bacterium can degrade EDTA in the presence of Pu and decrease Pu mobility. However, our recent studies indicate that while Pu(IV)-EDTA is stable in simple aqueous systems, it is not stable in the presence of relatively soluble Fe(III) compounds (i.e., Fe(OH){sub 3}(s)--2-line ferrihydrite). Since most DOE sites have Fe(III) containing sediments, Pu(IV) in likely not the mobile form of Pu-EDTA in groundwater. The only other Pu-EDTA complex stable in groundwater relevant to DOE sites would be Pu(III)-EDTA, which only forms under anaerobic conditions. Research is therefore needed in this brand new project to investigate the biotransformation of Pu and Pu-EDTA under anaerobic conditions. The biotransformation of Pu and Pu-EDTA under various anaerobic regimes is poorly understood including the reduction kinetics of Pu(IV) to Pu(III) from soluble (Pu(IV)-EDTA) and insoluble Pu(IV) as PuO2(am) by metal reducing bacteria, the redox conditions required for this reduction, the strength of the Pu(III)-EDTA complex, how the Pu(III)-EDTA complex competes with other dominant anoxic soluble metals (e.g., Fe(II)), and the oxidation kinetics of Pu(III)-EDTA. Finally, the formation of a stable soluble Pu(III)-EDTA complex under anaerobic conditions would require degradation of the EDTA complex to limit Pu(III) transport in geologic environments. Anaerobic EDTA degrading microorganisms have not been isolated. These knowledge gaps preclude the development of a mechanistic understanding of how anaerobic conditions will influence Pu and Pu-EDTA fate and transport to assess, model, and design approaches to stop

  12. Benzylsuccinate Formation as a Means of Anaerobic Toluene Activation by Sulfate-Reducing Strain PRTOL1

    PubMed Central

    Beller, H. R.; Spormann, A. M.

    1997-01-01

    Permeabilized cells of toluene-mineralizing, sulfate-reducing strain PRTOL1 catalyzed the addition of toluene to fumarate to form benzylsuccinate under anaerobic conditions. Recent in vitro studies with two toluene-mineralizing, denitrifying bacteria demonstrated the same fumarate addition reaction and indicated that it may be the first step of anaerobic toluene degradation. This study with strain PRTOL1 shows that anaerobic toluene activation by fumarate addition occurs in bacteria as disparate as sulfate-reducing and denitrifying species (members of the delta and beta subclasses of the Proteobacteria, respectively). PMID:16535701

  13. [Anaerobic bacteria 150 years after their discovery by Pasteur].

    PubMed

    García-Sánchez, José Elías; García-Sánchez, Enrique; Martín-Del-Rey, Ángel; García-Merino, Enrique

    2015-02-01

    In 2011 we celebrated the 150th anniversary of the discovery of anaerobic bacteria by Louis Pasteur. The interest of the biomedical community on such bacteria is still maintained, and is particularly focused on Clostridium difficile. In the past few years important advances in taxonomy have been made due to the genetic, technological and computing developments. Thus, a significant number of new species related to human infections have been characterised, and some already known have been reclassified. At pathogenic level some specimens of anaerobic microflora, that had not been isolated from human infections, have been now isolated in some clinical conditions. There was emergence (or re-emergence) of some species and clinical conditions. Certain anaerobic bacteria have been associated with established infectious syndromes. The virulence of certain strains has increased, and some hypotheses on their participation in certain diseases have been given. In terms of diagnosis, the routine use of MALDI-TOF has led to a shortening of time and a cost reduction in the identification, with an improvement directly related to the improvement of data bases. The application of real-time PCR has been another major progress, and the sequencing of 16srRNA gene and others is currently a reality for several laboratories. Anaerobes have increased their resistance to antimicrobial agents, and the emergence of resistance to carbapenems and metronidazole, and multi-resistance is a current reality. In this situation, linezolid could be an effective alternative for Bacteroides. Fidaxomicin is the only anti-anaerobic agent introduced in the recent years, specifically for the diarrhoea caused by C.difficile. Moreover, some mathematical models have also been proposed in relation with this species. Copyright © 2013 Elsevier España, S.L.U. y Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica. All rights reserved.

  14. Potential application of anaerobic extremophiles for hydrogen production

    NASA Astrophysics Data System (ADS)

    Pikuta, Elena V.; Hoover, Richard B.

    2004-11-01

    In processes of the substrate fermentation most anaerobes produce molecular hydrogen as a waste end product, which often controls the culture growth as an inhibitor. Usually in nature the hydrogen is easily removed from an ecosystem, due to its physical features, and an immediate consumption by the secondary anaerobes that sometimes behave as competitors for electron donors; a classical example of this kind of substrate competition in anaerobic microbial communities is the interaction between methanogens and sulfate- or sulfur-reducers. Previously, on the mixed cultures of anaerobes at neutral pH, it was demonstrated that bacterial hydrogen production could provide a good alternative energy source. At neutral pH the original cultures could easily contaminated by methanogens, and the most unpleasant side effect of these conditions is the development of pathogenic bacteria. In both cases the rate of hydrogen production was dramatically decreased since some part of the hydrogen was transformed to methane, and furthermore, the cultivation with pathogenic contaminants on an industrial scale would create an unsafe situation. In our laboratory the experiments with obligately alkaliphilic bacteria producing hydrogen as an end metabolic product were performed at different conditions. The mesophilic, haloalkaliphilic and obligately anaerobic bacterium Spirochaeta americana ASpG1T was studied and various cultivation regimes were compared for the most effective hydrogen production. In a highly mineralized media with pH 9.5-10.0 not many known methanogens are capable of growth, and the probability of developing pathogenic contaminants is theoretically is close to zero (in medicine carbonate- saturated solutions are applied as antiseptics). Therefore the cultivation of alkaliphilic hydrogen producing bacteria could be considered as a safe and economical process for large-scale industrial bio-hydrogen production in the future. Here we present and discuss the experimental data

  15. 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.

  16. PCB dechlorination in anaerobic soil slurry reactors

    SciTech Connect

    Klasson, K.T.; Evans, B.S.

    1993-11-29

    Many industrial locations, including the US Department of Energy`s, have identified needs for treatment of polychlorinated biphenyl (PCB) wastes and remediation of PCB-contaminated sites. Biodegradation of PCBs is a potentially effective technology for the treatment of PCB-contaminated soils and sludges, including mixed wastes; however, a practical remediation technology has not yet been demonstrated. In laboratory experiments, soil slurry bioreactors inoculated with microorganisms extracted from PCB-contaminated sediments from the Hudson River have been used to obtain anaerobic dechlorination of PCBS. The onset of dechlorination activity can be accelerated by addition of nutritional amendments and inducers. After 15 weeks of incubation with PCB-contaminated soil and nutrient solution, dechlorination has been observed under several working conditions. The best results show that the average chlorine content steadily dropped from 4.3 to 3.5 chlorines per biphenyl over a 15-week period.

  17. Anaerobic Sulfur Metabolism Coupled to Dissimilatory Iron Reduction in the Extremophile Acidithiobacillus ferrooxidans

    PubMed Central

    Osorio, Héctor; Mangold, Stefanie; Denis, Yann; Ñancucheo, Ivan; Esparza, Mario; Johnson, D. Barrie; Bonnefoy, Violaine; Dopson, Mark

    2013-01-01

    Gene transcription (microarrays) and protein levels (proteomics) were compared in cultures of the acidophilic chemolithotroph Acidithiobacillus ferrooxidans grown on elemental sulfur as the electron donor under aerobic and anaerobic conditions, using either molecular oxygen or ferric iron as the electron acceptor, respectively. No evidence supporting the role of either tetrathionate hydrolase or arsenic reductase in mediating the transfer of electrons to ferric iron (as suggested by previous studies) was obtained. In addition, no novel ferric iron reductase was identified. However, data suggested that sulfur was disproportionated under anaerobic conditions, forming hydrogen sulfide via sulfur reductase and sulfate via heterodisulfide reductase and ATP sulfurylase. Supporting physiological evidence for H2S production came from the observation that soluble Cu2+ included in anaerobically incubated cultures was precipitated (seemingly as CuS). Since H2S reduces ferric iron to ferrous in acidic medium, its production under anaerobic conditions indicates that anaerobic iron reduction is mediated, at least in part, by an indirect mechanism. Evidence was obtained for an alternative model implicating the transfer of electrons from S0 to Fe3+ via a respiratory chain that includes a bc1 complex and a cytochrome c. Central carbon pathways were upregulated under aerobic conditions, correlating with higher growth rates, while many Calvin-Benson-Bassham cycle components were upregulated during anaerobic growth, probably as a result of more limited access to carbon dioxide. These results are important for understanding the role of A. ferrooxidans in environmental biogeochemical metal cycling and in industrial bioleaching operations. PMID:23354702

  18. 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.

  19. Factors involved in anaerobic growth of Saccharomyces cerevisiae.

    PubMed

    Ishtar Snoek, I S; Yde Steensma, H

    2007-01-01

    Life in the absence of molecular oxygen requires several adaptations. Traditionally, the switch from respiratory metabolism to fermentation has attracted much attention in Saccharomyces cerevisiae, as this is the basis for the use of this yeast in the production of alcohol and in baking. It has also been clear that under anaerobic conditions the yeast is not able to synthesize sterols and unsaturated fatty acids and that for anaerobic growth these have to be added to the media. More recently it has been found that many more factors play a role. Several other biosynthetic reactions also require molecular oxygen and the yeast must have alternatives for these. In addition, the composition of the cell wall and cell membrane show major differences when aerobic and anaerobic cells are compared. All these changes are reflected by the observation that the transcription of more than 500 genes changes significantly between aerobically and anaerobically growing cultures. In this review we will give an overview of the factors that play a role in the survival in the absence of molecular oxygen.

  20. Anaerobic and aerobic fitness profiling of competitive surfers.

    PubMed

    Farley, Oliver; Harris, Nigel K; Kilding, Andrew E

    2012-08-01

    Despite widespread popularity of competitive surfing internationally, very little research has investigated the physiological profile of surf athletes and attempted to identify the relationships between physiological measures and surfing performance. This study determined the peak oxygen uptake (V(O2)peak) from an incremental ramp test and anaerobic power (watts) during a 10-second maximal-paddling burst using a surf paddle-specific modified kayak ergometer, customized with a surfboard and hand paddles. Twenty nationally ranked surf athletes volunteered to participate in the VV(O2)peak test, and 8 also participated in the anaerobic power test. The interrelationships between these components of athletic performance and surfing performance, as assessed by season rank, were determined using Pearsons correlations. We found a significant relationship between anaerobic power and season rank (r = 0.55, p = 0.05). No significant relationship between VV(O2)peak and season rank was found (r = -0.02, p = 0.97). Although correlations do not imply cause and effect, such a finding provides theoretical support for the importance of including anaerobic paddling power in assessment batteries and conditioning practice for surf athletes.

  1. Improving products of anaerobic sludge digestion by microaeration.

    PubMed

    Jenicek, P; Celis, C A; Krayzelova, L; Anferova, N; Pokorna, D

    2014-01-01

    Biogas, digested sludge and sludge liquor are the main products of anaerobic sludge digestion. Each of the products is influenced significantly by specific conditions of the digestion process. Therefore, any upgrade of the digestion technology must be considered with regard to quality changes in all products. Microaeration is one of the methods used for the improvement of biogas quality. Recently, microaeration has been proved to be a relatively simple and highly efficient biological method of sulfide removal in the anaerobic digestion of biosolids, but little attention has been paid to comparing the quality of digested sludge and sludge liquor in the anaerobic and microaerobic digestion and that is why this paper primarily deals with this area of researc