Showing papers on "Methanogen published in 2006"
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TL;DR: The simple methanogenic population in the thermophilic anaerobic digester significantly responded to the environmental conditions, especially to the concentration of VFAs.
Abstract: In this study, the microbial community succession in a thermophilic methanogenic bioreactor under deteriorative and stable conditions that were induced by acidification and neutralization, respectively, was investigated using PCR-mediated single-strand conformation polymorphism (SSCP) based on the 16S rRNA gene, quantitative PCR, and fluorescence in situ hybridization (FISH). The SSCP analysis indicated that the archaeal community structure was closely correlated with the volatile fatty acid (VFA) concentration, while the bacterial population was impacted by pH. The archaeal community consisted mainly of two species of hydrogenotrophic methanogen (i.e., a Methanoculleus sp. and a Methanothermobacter sp.) and one species of aceticlastic methanogen (i.e., a Methanosarcina sp.). The quantitative PCR of the 16S rRNA gene from each methanogen revealed that the Methanoculleus sp. predominated among the methanogens during operation under stable conditions in the absence of VFAs. Accumulation of VFAs induced a dynamic transition of hydrogenotrophic methanogens, and in particular, a drastic change (i.e., an approximately 10,000-fold increase) in the amount of the 16S rRNA gene from the Methanothermobacter sp. The predominance of the one species of hydrogenotrophic methanogen was replaced by that of the other in response to the VFA concentration, suggesting that the dissolved hydrogen concentration played a decisive role in the predominance. The hydrogenotrophic methanogens existed close to bacteria in aggregates, and a transition of the associated bacteria was also observed by FISH analyses. The degradation of acetate accumulated during operation under deteriorative conditions was concomitant with the selective proliferation of the Methanosarcina sp., indicating effective acetate degradation by the aceticlastic methanogen. The simple methanogenic population in the thermophilic anaerobic digester significantly responded to the environmental conditions, especially to the concentration of VFAs.
306 citations
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TL;DR: Northern acidic peatlands are important sources of atmospheric methane, yet the methanogens in them are poorly characterized, and examined methanogenic activities and methanogen populations at different depths in twoPeatlands, McLean bog and Chicago bog, finding further evidence for the associations of most organisms in this group with acidic habitats.
Abstract: Northern acidic peatlands are important sources of atmospheric methane, yet the methanogens in them are poorly characterized. We examined methanogenic activities and methanogen populations at different depths in two peatlands, McLean bog (MB) and Chicago bog (CB). Both have acidic (pH 3.5-4.5) peat soils, but the pH of the deeper layers of CB is near-neutral, reflecting its previous existence as a neutral-pH fen. Acetotrophic and hydrogenotrophic methanogenesis could be stimulated in upper samples from both bogs, and phylotypes of methanogens using H2/CO2 (Methanomicrobiales) or acetate (Methanosarcinales) were identified in 16S rRNA gene clone libraries and by terminal restriction fragment length polymorphism (T-RFLP) analyses using a novel primer/restriction enzyme set that we developed. Particularly dominant in the upper layers was a clade in the Methanomicrobiales, called E2 here and the R10 or fen group elsewhere, estimated by quantitative polymerase chain reaction to be present at approximately 10(8) cells per gram of dry peat. Methanogenic activity was considerably lower in deeper samples from both bogs. The methanogen populations detected by T-RFLP in deeper portions of MB were mainly E2 and the uncultured euryarchaeal rice cluster (RC)-II group, whereas populations in the less acidic CB deep layers were considerably different, and included a Methanomicrobiales clade we call E1-E1', as well as RC-I, RC-II, marine benthic group D, and a new cluster that we call the subaqueous cluster. E2 was barely detectable in the deeper samples from CB, further evidence for the associations of most organisms in this group with acidic habitats.
178 citations
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TL;DR: It is demonstrated that the optimum pH for methanogenesis by this organism is lower than that of any previously described methanogen.
Abstract: Microbiologists have succeeded in culturing the most acid-loving methanogen ever discovered. The new species, a member of the Methanomicrobiales group, was found in McLean Bog in New York State. It grows at a preferred pH of around 5, beating the previous record-holder, Methanobacterium espanolae, which has an optimum pH of between 5.5 and 6.0. Although some other methanogens can survive a pH as low as 4.5, the new species is the first to show growth and optimal methanogenesis in such acidic conditions. Microbes living in acidic soils are important sources of atmospheric methane, which is linked to global warming. Acidic peatlands are among the largest natural sources of atmospheric methane and harbour a large diversity of methanogenic Archaea1. Despite the ubiquity of methanogens in these peatlands, indigenous methanogens capable of growth at acidic pH values have resisted culture and isolation2,3,4; these recalcitrant methanogens include members of an uncultured family-level clade in the Methanomicrobiales prevalent in many acidic peat bogs in the Northern Hemisphere1,5,6. However, we recently succeeded in obtaining a mixed enrichment culture of a member of this clade7. Here we describe its isolation and initial characterization. We demonstrate that the optimum pH for methanogenesis by this organism is lower than that of any previously described methanogen.
163 citations
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TL;DR: In this article, microcosm experiments were carried out to examine the acute effects of increasing salinity on the anaerobic cycling of carbon, nutrients (N, P, and S), metals (Fe and Mn), and microbial community structure in sediments from a non-salt-impacted freshwater wetland.
Abstract: Wetlands in many inland catchments are being subjected to increasing salinity. To expand our limited understanding of how increasing salinity will alter carbon and nutrient dynamics in freshwater sediments, we carried out microcosm experiments to examine the acute effects of increasing salinity on the anaerobic cycling of carbon, nutrients (N, P, and S), metals (Fe and Mn), and microbial community structure in sediments from a non-salt-impacted freshwater wetland. Sediments were collected from a wetland on the River Murray floodplain, south eastern Australia and incubated with NaCl concentrations ranging from 0 to 100 mmol L−1. Increasing NaCl concentration led to the immediate release of between about 80 and 190 μmol L−1 ammonium and 235 to 3300 μmol L−1 Fe(II) from the sediments, the amount released ‘increasing with NaCl concentration. Conversely, net phosphate release decreased with increasing NaCl concentration. The overall microbial community structure, determined from phospholipid fatty acid profiles, changed only at the highest NaCl loadings, with evidence of a decrease in microbial diversity. Bacterial community structure, determined by examining terminal restriction fragment length polymorphism (T-RFLP) of the bacterial 16S rRNA gene, showed little response to increasing NaCl concentration. Conversely, the archaeal (methanogen) population, determined by examining T-RFLP of the archaeal 16S rRNA gene, showed significant changes with increasing NaCl loading. This shift corresponded with a significant decrease in methane production from salt-impacted sediments and therefore shows a linkage between microbial community structure and an ecosystem process.
145 citations
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TL;DR: Based on the phylogenetic and phenotypic analyses, the novel species Methanosaeta harundinacea sp.
Abstract: Two methanogenic strains, 8AcT and 6Ac, were isolated from an upflow anaerobic sludge blanket reactor treating beer-manufacture wastewater in Beijing, China. Cells of strains 8AcT and 6Ac were rod-shaped (0·8–1·0×3–5 μm) and non-motile, occurring singly or in pairs; however, at high cell density the cells were arranged in long chains within a common sheath. The two strains used acetate exclusively for growth and methane production. The specific growth rate of strain 8AcT was 0·030 h−1 when growing in acetate (20 mM) at 37 °C. The temperature range for growth was 25–45 °C, with the fastest growth at 34–37 °C. The pH range for growth and methane production was 6·5–9·0, with the fastest growth at pH 7·2–7·6. The G+C content of genomic DNA of strain 8AcT was 55·7 mol%. Phylogenetic analysis based on 16S rRNA gene sequence similarity showed that the novel strains clustered with Methanosaeta species; the 16S rRNA gene sequence similarities between strain 8AcT and Methanosaeta concilii DSM 3013 and ‘Methanosaeta thermophila’ DSM 6194 were 92·5 and 87·3 %, respectively. The sequence similarity levels of mcrA, the gene encoding the α-subunit of methyl-coenzyme M reductase, and of the deduced amino acids of mcrA, between strain 8AcT and Methanosaeta concilii DSM 3671T were 36 and 78·9 %, respectively. Based on the phylogenetic and phenotypic analyses, the novel species Methanosaeta harundinacea sp. nov. is proposed, with strain 8AcT (=JCM 13211T=CGMCC 1.5026T) as the type strain.
134 citations
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TL;DR: Hydrogen production from the inocula with bacterial stress enrichment was 1.9–9.8 times greater when compared with control sludge, and chemical acidification using perchloric acid showed the best hydrogen production potential, irrespective of preacidification.
Abstract: Methodology was evaluated to selectively enrich hydrogen-producing species present in biological sludge produced during organic wastewater treatment. The influence of bacterial stress enrichment on anaerobic hydrogen-producing microorganisms was investigated in batch tests using serum bottles. Enrichment conditions investigated included application of acute physical and chemical stresses: wet heat, dry heat and desiccation, use of a methanogen inhibitor, freezing and thawing, and chemical acidification with and without preacidification of the sludge at pH 3. For each enrichment sample, cultivation pH value was set at an initial value of 7. After application of selective enrichment (by bacterial stress), hydrogen production was significantly higher than that of untreated original sludge. Hydrogen production from the inocula with bacterial stress enrichment was 1.9–9.8 times greater when compared with control sludge. Chemical acidification using perchloric acid showed the best hydrogen production potential, irrespective of preacidification. Enhancement is due to the selective capture of hydrogen-producing sporeformers, which induces altered anaerobic fermentative metabolism.
120 citations
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TL;DR: A mesophilic anaerobic chemostat that was continuously fed with synthetic wastewater containing propionate as the sole source of carbon and energy was constructed and it was demonstrated that rRNA genes affiliated with the genus Syntrophobacter predominated at the low dilution rate, whereas r RNA genes affiliated with the phylum Firmicutes predominated with the higher dilution rates.
Abstract: We constructed a mesophilic anaerobic chemostat that was continuously fed with synthetic wastewater containing propionate as the sole source of carbon and energy. Steady-state conditions were achieved below the critical dilution rate of 0.3 d −1 with almost complete substrate degradation. The propionate-degrading methanogenic communities in the chemostat at dilution rates of 0.01, 0.08, and 0.3 d −1 were analyzed using molecular biological techniques. Fluorescence in situ hybridization with archaeal and bacterial domain-specific probes showed that archaeal cells predominated throughout the three dilution rates. Archaeal-16S rRNA gene clone library analysis and quantitative real-time polymerase chain reaction studies showed that hydrogenotrophic methanogen rRNA genes closely related to Methanoculleus was detected at a dilution rate of 0.01 d −1 , whereas rRNA genes closely related to the Methanoculleus and Methanospirillum genera were detected at dilution rates of 0.08 and 0.3 d −1 . The aceticlastic methanogen, Methanosaeta , was detected throughout the three dilution rates. Bacterial-rRNA gene clone library analysis and denaturing gradient gel electrophoresis demonstrated that rRNA genes affiliated with the genus Syntrophobacter predominated at the low dilution rate, whereas rRNA genes affiliated with the phylum Firmicutes predominated at the higher dilution rates. A significant number of rRNA genes affiliated with the genus Pelotomaculum were detected at dilution rate of 0.3 d −1 . The diversity of genes encoding acetate kinase agreed closely with the results of the rRNA gene analysis. The dilution rates significantly altered the archaeal and bacterial communities in the propionate-fed chemostat.
92 citations
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TL;DR: A study of the performance and microbial communities of a continuous stirred tank reactor (CSTR) treating two-phases olive mill solid wastes (OMSW) was carried out at laboratory-scale and the Firmicutes were the most abundant group, followed by the Chloroflexi and the Gamma-Proteobacteria (Pseudomonas species as the major representative).
85 citations
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TL;DR: This study fingerprint and identify the methanogens present in three different types of UASB granules that had been used to treat winery, brewery and peach-lye canning effluents using polymerase chain reaction (PCR)-based denaturing gradient gel electrophoresis (DGGE) and DNA sequence analysis.
75 citations
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TL;DR: In this paper, the molecular and carbon isotopic compositions of polar isopranyl glycerol ether lipids, which are direct indicators of viable archaea, were investigated in near surface sediments from a methane seep in the Nankai Trough (off central Japan).
69 citations
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TL;DR: Two methanogenic cultures were enriched from acidic peat soil using a growth medium buffered to c.
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TL;DR: Methane production was negligible in the three youngest fen sites and showed the highest rates in the oligotrophic fen site (site 4), and successful PCR amplification revealed the presence of a methanogen community in all five sites along the study transect.
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TL;DR: Research designed to determine how long certain species of methanogens can survive desiccation on a Mars soil simulant, JSC Mars-1, found that Methanosarcina barkeri survived Desiccation for 10 days, while Methanobacterium formicicum and Methanothermobacter wolfeii were able to survive for 25 days.
Abstract: The relatively recent discoveries that liquid water likely existed on the surface of past Mars and that methane currently exists in the martian atmosphere have fueled the possibility of extant or extinct life on Mars. One possible explanation for the existence of the methane would be the presence of methanogens in the subsurface. Methanogens are microorganisms in the domain Archaea that can metabolize molecular hydrogen as an energy source and carbon dioxide as a carbon source and produce methane. One factor of importance is the arid nature of Mars, at least at the surface. If one is to assume that life exists below the surface, then based on the only example of life that we know, liquid water must be present. Realistically, however, that liquid water may be seasonal just as it is at some locations on our home planet. Here we report on research designed to determine how long certain species of methanogens can survive desiccation on a Mars soil simulant, JSC Mars-1. Methanogenic cells were grown on JSC Mars-1, transferred to a desiccator within a Coy anaerobic environmental chamber, and maintained there for varying time periods. Following removal from the desiccator and rehydration, gas chromatographic measurements of methane indicated survival for varying time periods. Methanosarcina barkeri survived desiccation for 10 days, while Methanobacterium formicicum and Methanothermobacter wolfeii were able to survive for 25 days.
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TL;DR: As butyrate appears to be an important mediator of colonic health, the inverse relationship with methanogen uncovered here suggests that methanogens may be useful biomarkers of bowel health.
Abstract: Background : We have examined the relationship between the presence and numbers of methanogenic archaea in the faeces of humans and levels of the short chain fatty acids (SCFAs), especially butyrate, to gain insight into factors that may influence bowel health. In doing so, we have carried out the first cultivation-independent, molecular analysis of methanogen diversity and abundance in the human gastrointestinal tract. Materials and methods : The faeces of eight healthy individuals on their normal diets were collected weekly over a 12 week period. DNA was extracted from the faeces and PCR-based assays, using methanogen-specific 16S rRNA gene primer sets, were used in conjunction with denaturing gradient gel electrophoresis (DGGE) to identify and enumerate methanogens present. Results : Methanogens were detected in all faecal samples from five of the eight individuals tested. Three distinct methanogen phylotypes were found, with two or three phylotypes present in some individuals. DNA sequencing of DGGE bands indicated that all phylotypes were closely related to Methanobrevibacter smithii (99-100%). Real-time PCR analyses revealed that faecal methanogen numbers varied significantly between individuals and over time by up to two orders of magnitude. Concentrations of acetate, butyrate and propionate in faeces also varied significantly between individuals and with time. There was a negative correlation between mean faecal butyrate concentration and methanogen abundance (R=-0.729, p<0.05, n=8), but no significant relationship existed for acetate, propionate or total SCFAs, and no relationship was found between total bacterial abundance and pH, SCFA concentration or methanogen abundance. Conclusion : As butyrate appears to be an important mediator of colonic health, the inverse relationship with methanogens uncovered here suggests that methanogens may be useful biomarkers of bowel health. Key words: methanogens, butyrate, colorectal cancer
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TL;DR: Analysis of the 16S rRNA gene libraries from DNA extracted directly from the sediment samples revealed phylotypes that were either distantly related to cultivated methanogens or possible anaerobic methane oxidizers related to the ANME-1 andANME-2 groups of the Archaea, suggesting that methanogen represented only a small proportion of the archaeal community.
Abstract: Little is known about the methanogenic degradation of acetate, the fate of molecular hydrogen and formate or the ability of methanogens to grow and produce methane in cold, anoxic marine sediments. The microbes that produce methane were examined in permanently cold, anoxic marine sediments at Hydrate Ridge (44°35' N, 125°10' W, depth 800 m). Sediment samples (15 to 35 cm deep) were collected from areas of active methane ebullition or areas where methane hydrates occurred. The samples were diluted into enrichment medium with formate, acetate or trimethylamine as catabolic substrate. After 2 years of incubation at 4 °C to 15 °C, enrichment cultures produced methane. PCR amplification and sequencing of the rRNA genes from the highest dilutions with growth suggested that each enrichment culture contained a single strain of methanogen. The level of sequence similarity (91 to 98%) to previously characterized prokaryotes suggested that these methanogens belonged to novel genera or species within the orders Methanomicrobiales and Methanosarcinales. Analysis of the 16S rRNA gene libraries from DNA extracted directly from the sediment samples revealed phylotypes that were either distantly related to cultivated methanogens or possible anaerobic methane oxidizers related to the ANME-1 and ANME-2 groups of the Archaea. However, no methanogenic sequences were detected, suggesting that methanogens represented only a small proportion of the archaeal.
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TL;DR: This report is the first description of psychrotolerant as well as marine butyrate--and propionate-oxidizing syntrophic organisms.
Abstract: Two anaerobic, psychrotolerant, syntrophic strains were enriched from permanently cold, shallow anoxic marine sediments in Skan Bay, Alaska. One strain, AK-B(T), oxidized butyrate syntrophically and was isolated in defined coculture with a H(2)-using methanogen or in a dixenic coculture that also contained an acetate-scavenging methanogen. The other enrichment culture syntrophically oxidized propionate. The growth of these syntrophic cultures was very slow: approximately 1 year for cocultures of strain AK-B(T) to form colonies and >1 year for the propionate-oxidizing enrichment to form colonies. Neither culture grew axenically when supplied with the catabolic substrates crotonate, pyruvate, malate, or sulfate plus butyrate or propionate. Strain AK-B(T) catabolized iso-butyrate in syntrophic coculture but did not catabolize valerate or caproate. Phylogenetic analyses of the 16S rRNA gene sequence suggested that strain AK-B(T) was only distantly related to cultivated sulfate-reducing bacteria, and that this strain represented a new genus. We propose Algorimarina butyrica, with strain AK-B(T) (=OCM 842(T)), as the type strain. This report is the first description of psychrotolerant as well as marine butyrate--and propionate-oxidizing syntrophic organisms.
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TL;DR: In this article, the authors analyzed the interrelations between gas formation and sediment physical, chemical and biological qualities, and found that the extent and amplitude of each phase varied strongly between sediment and could be correlated well with only a few standard analytical parameters, despite the strong heterogeneity of sediment with respect to chemical, physical, and biological characteristics.
Abstract: Under anoxic conditions typically prevailing in disposal sites for dredged sediment, methanogenesis is the terminal step during microbial degradation of sediment organic matter. Sediment gas production may pose several problems to site management and post-closure utilisation. Depending on the magnitude of gas/methane formation and the intended utilisation of the site, countermeasures will have to be effected during and after deposition of the dredged material. For this purpose it may be of interest to pre-estimate the extent of gas formation from simple sediment variables. Therefore, the aim of the investigations presented here was to analyse the interrelations between gas formation and sediment physical, chemical and biological qualities. Freshly sampled riverbed sediment from nine German federal waterways was analysed for standard solid physical and chemical parameters, pore water composition, cell counts of methanogenic and sulfate-reducing bacteria, and gas formation over a period of 500 days. Particle size and density fractionation were carried out in order to characterise organic matter quality. Correlations between methane formation and sediment chemical, physical and microbiological characteristics were tested using linear and multiple correlation analysis. The selected sediments, including two with marine influence, differed strongly regarding texture, chemical parameters, pore water composition, and methanogen cell counts. The course of methane formation was found to follow distinct phases. The commencement of methane formation was preceded by a lag phase of variable duration. The lag phase was followed by a strong increase of the methane formation rate up to a sediment-characteristic maximum of 5–30 nmol CH4 h–1 g dw–1. Eventually, the rate of methane formation decreased and reached a more stable, long-term level. The extent and amplitude of each phase varied strongly between sediments and could be correlated well with only a few standard analytical parameters, despite the strong heterogeneity of sediment with respect to chemical, physical, and biological characteristics. Lag phase duration depended strongly on the content of inorganic electron acceptors and also on the number of methanogens present at the beginning of the experiment. Maximum and steady state methanogenesis were mainly determined by sediment total nitrogen. As analysis of sediment density fractions revealed that total nitrogen reflected the share of readily degradable macroorganic matter. The results imply that the observed methane formation is a function of the temporally changing balance of the availability of electron acceptors and H2, and the share of easily degradable organic matter. For fresh riverbed sediments, the latter may be deduced from total nitrogen content. Overall, the results showed that methane formation by freshly dredged material may well be pre-estimated from standard analytical data within the first few years of deposition. However, the differently degradable organic matter pools will change over time with respect to size, chemical nature and association with the sediment mineral phase. It can thus be expected that the correlations found in this study will not be readily transferable to older materials. Further studies on the gas formation and organic matter quality by older sediments, e.g. from older dredged material disposal sites of known age, should be conducted and results should be combined with existing organic matter degradation models in order to improve the prediction of sediment gas formation over time.
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TL;DR: Process performances of an upflow anaerobic filter treating olive mill wastewater and the response of methanogenic Archaea to increasing volumetric organic load were studied, indicating that VOL variation affected the methanogen PCR titre but not the archaeal community structure.
Abstract: Process performances of an upflow anaerobic filter treating olive mill wastewater and the response of methanogenic Archaea to increasing volumetric organic load (VOL) were studied. At a VOL of 15 g chemical oxygen demand (COD) L -1 day -1 , 90% of the influent COD was removed. Following a VOL increase from 6 to 15 g COD L -1 day -1 , the polymerase chain reaction (PCR) titre of hydrogenotrophic Methanobacterium, determined by magnetic capture of the target DNA and group-specific PCR based on the 16S rRNA gene, decreased from 10 11 to 10 8 cells g -1 sludge, while that of Methanomicrobiaceae and relatives increased from 10 4 to 10 6 cells g -1 sludge. Methanosaeta-like acetoclastic methanogens were less affected by VOL variation and dominated at high VOL with a 16S rRNA gene PCR titre of 10 9 cells g -1 sludge. Single-strand conformation polymorphism analysis of the PCR-amplified archaeal 16S rRNA gene showed a stable band pattern, indicating that VOL variation affected the methanogen PCR titre but not the archaeal community structure.
01 Jan 2006
TL;DR: In this article, the influence of trace metals, like cobalt, nickel, tungsten and molybdenum on the conversion of methanol and propionate were studied.
Abstract: Trace metals are essential for the growth and metabolism of anaerobic microorganisms, duo to their roles in key enzymes or cofactors of metabolic pathways. The requirement of trace metals has been recognized. But, proper dosing of these metals in anaerobic treatment system as nutrient still is a great challenge, since dosing of a metal at a high concentration is toxic for growth of microorganisms, and dosing of a specific metal may lead out-compete of one group of microorganisms by the other. In order to obtain knowledge for optimization of metal dosing of anaerobic treatment system, the influence of trace metals, like cobalt, nickel, tungsten and molybdenum on the conversion of methanol and propionate were studied in this research. By using cobalt-sufficient medium, a methanogenic enrichment culture was enriched from a thermophilic lab-scale UASB reactor fed with methanol as carbon and energy source. From which a novel thermophilic obligate methylotrophic methanogenic archaeon , strain L2FAW T , was isolated and characterized as Methanomethylovorans thermophila . The growth of strain L2FAW T on methanol is stimulated by the addition of cobalt; the optimal cobalt concentration is 0.5 to 2 M. therefore, cobalt is important for direct methanol conversion by this methanogen. On the other hand, a syntrophic coculture of methanol degradation was enriched from the same sludge by using cobalt deficient medium, which consisted of a homoacetogen and a hydrogenotrophic methanogen. This coculture degrades methanol partially to acetate and partially to methane, depending on the presence of cobalt. Acetate is the main product when cobalt is presence at high concentration; otherwise methane is formed as dominant products. Therefore, cobalt plays a role in the regulation of the pathway of methanol conversion. The optimal cobalt concentration of the coculture for complete methanogenesis from methanol is about 0.1 M. A thermophilic spore-forming bacteria, strain AMP, was isolated from the coculture , and it is most closely related to Moorella thermoacetica based on 16S rRNA analysis. Despite its high DNA-DNA homology with M. thermoacetica , strain AMP differs from M. thermoacetica on its inability to use glucose, formate and H 2 /CO 2 , and its unique hydrogenogenic growth on CO. Moreover, strain AMP can grow on formate in a coculture with a hydrogenotrophic methanogen. It is described for the first time that a bacterium can grow on the conversion of formate to H 2 and bicarbonate provided that hydrogen is consumed by a methanogen. The effect of cobalt and nickel on the corrinoid and F430 content and on growth of Methanosarcina barkeri on methanol was studied. Cobalt and nickel limitation was achieved and competition between cobalt and nickel uptake was observed. Uptake efficiency of cobalt was high at low cobalt concentration and decreased when the cobalt concentration in the medium was increased. Corrinoid and F430 content correlated positively with the cell content of the corresponding metal, but incorporation in the corrinoid and F430 was significant less at low cell metal contents, ranging from 35% to 80% for corrinoid and 5% to 15% for F430. The trace elements tungsten and molybdenum play an essential role in the growth of anaerobic microorganisms. Depletion of tungsten and/or molybdenum in the media did not affect axenic growth of Syntrophobacter fumaroxidans on propionate+fumarate , indicating under these conditions this organism does not have a high tungsten or molybdenum requirement. However, growth of Methanospirillum hungatei on either formate or hydrogen and carbon dioxide required tungsten, and molybdenum can replace tungsten to some extent. Growth of the Syntrophobacter-Methanospirillum coculture on propionate is significantly affected by the addition of these two metals. Measurement of enzyme levels in cell extracts of syntrophically grown cells indicated that the levels of hydrogenase and formate dehydrogenase activity were correlated with the methane formation rates by the cocultures , which suggests both hydrogen and formate play important role in syntrophic propionate oxidation.
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TL;DR: It appears that aerobic manipulations for relatively short periods of time with at least a few species of methanogens may not lead to loss of viability.
Abstract: The recent discovery of methane in the martian atmosphere is arguably one of the most important discoveries in the field of astrobiology. One possible source of this methane could be a microorganism analogous to those on Earth in the domain Archaea known as methanogens. Methanogens are described as obligately anaerobic, and methods developed to work with methanogens typically include anaerobic media and buffers, gassing manifolds, and possibly anaerobic chambers. To determine if the time, effort, and supplies required to maintain anaerobic conditions are necessary to maintain viability, we compared anaerobically washed cells with cells that were washed in the presence of atmospheric oxygen. Anaerobic tubes were opened, and cultures were poured into plastic centrifuge tubes, centrifuged, and suspended in fresh buffer, all in the presence of atmospheric oxygen. Washed cells from both aerobic and anaerobic procedures were inoculated into methanogenic growth media under anaerobic conditions and incubated at temperatures conducive to growth for each methanogenic strain tested. Methane production was measured at time intervals using a gas chromatograph. In three strains, significant differences were not seen between aerobically and anaerobically washed cells. In one strain, there was significantly less methane production observed following aerobic washing at some time points; however, substantial methane production occurred following both procedures. Thus, it appears that aerobic manipulations for relatively short periods of time with at least a few species of methanogens may not lead to loss of viability. With the discovery of methane in the martian atmosphere, it is likely that there will be an increase in astrobiology-related methanogen research. The research reported here should simplify the methodology.
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TL;DR: Diverse yet unidentified rumen methanogen species exist in the co-cultures with anaerobic fungi isolated from the goat rumen, with the lowest similarity of DGGE profiles at 34.7%.
Abstract: Rumen methanogen diversity in the co-cultures with anaerobic fungi from goat rumen was analyzed. Mix-cultures of anaerobic fungi and methanogens were obtained from goat rumen using anaerobic fungal medium and the addition of penicillin and streptomycin and then subcultured 62 times by transferring cultures every 3 - 4d. Total DNA from the original rumen fluid and subcultured fungal cultures was used for PCR/DGGE and RFLP analysis. 16S rDNA of clones corresponding to representative OTUs were sequenced. Results showed that the diversity index (Shannon index) of the methanogens generated from DGGE profiles reduced from 1.32 to 0.99 from rumen fluid to fungal culture after 45 subculturing, with the lowest similarity of DGGE profiles at 34.7%. The Shannon index increased from 0.99 to 1.15 from the fungal culture after 45 subculturing to that after 62 subculturing, with the lowest similarity at 89.2% . A total of 5 OTUs were obtained from 69. clones using RFLP analysis and six clones representing the 5 OTUs respectively were sequenced. Of the 5 OTUs, three had their cloned 16S rDNA sequences most closely related to uncultured archaeal symbiont PA202 with the same similarity of 95 %, but had not closely related to any identified culturable methanogen. The rest two OTUs had their cloned 16S rDNA sequences sharing the same closest relative, uncultured rumen methanogen 956, with the same similarity of 97% .Their 16S rDNA sequences of these two OTUs also showed 97% similar to the closest identified culturable methanogen Methanobrevibacter sp. NT7. In conclusion, diverse yet unidentified rumen methanogen species exist in the co-cultures with anaerobic fungi isolated from the goat rumen.
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08 Nov 2006
TL;DR: In this paper, the authors proposed a method of co-producing hydrogen and methane with biomass and solid organic waste and through fermentation, which includes pyruvic acid, short chain fatty acid and small amount of H2 and CO2.
Abstract: The present invention relates to hydrogen and methane producing method and especially method of co-producing hydrogen and methane with biomass and solid organic waste and through fermentation. The method includes hydrolyzing and acidifying biomass and solid organic waste to produce pyruvic acid, short chain fatty acid and small amount of H2 and CO2; fermenting the mixture of pyruvic acid and short chain fatty acid under the action of fermenting hydrogenogen to produce great amount of hydrogen as well as small molecular weight side products ethanol, acetic acid, propionic acid and butyric acid; and further fermenting to convert the small molecular weight side products into methane under the action of methanogen. The apparatus can treat waste effectively to produce clean energy source material, and has high energy source converting rate and high matrix utilizing rate.
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TL;DR: Samples from an oil storage tank, which experienced unwanted periodic odorous gas emissions, contained up to 2,400/ml of thermophilic, lactate-utilizing, sulfate-reducing bacteria, indicated the presence of bacteria related to Garciella nitratireducens, Clostridium sp.
Abstract: Samples from an oil storage tank (resident temperature 40 to 60 degrees C), which experienced unwanted periodic odorous gas emissions, contained up to 2,400/ml of thermophilic, lactate-utilizing, sulfate-reducing bacteria. Significant methane production was also evident. Enrichments on acetate gave sheathed filaments characteristic of the acetotrophic methanogen Methanosaeta thermophila of which the presence was confirmed by determining the PCR-amplified 16S rDNA sequence. 16S rDNA analysis of enrichments, grown on lactate- and sulfate-containing media, indicated the presence of bacteria related to Garciella nitratireducens, Clostridium sp. and Acinetobacter sp. These sulfidogenic enrichments typically produced sulfide to a maximum concentration of 5-7 mM in media containing excess lactate and 10 mM sulfate or thiosulfate. Both the production of sulfide and the consumption of acetate by the enrichment cultures were inhibited by low concentrations of nitrite (0.5-1.0 mM). Hence, addition of nitrite may be an effective way to prevent odorous gas emissions from the storage tank.
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TL;DR: A comparison between the 14C content of the methane and dissolved inorganic carbon (DIC) in deep, terrestrial subsurface systems was used to assess the timing of microbial methanogenesis contributing to gases in fracture water samples from three mines in the Witwatersrand Basin, South Africa as discussed by the authors.
Abstract: A comparison between the 14C content of the methane and dissolved inorganic carbon (DIC) in deep, terrestrial subsurface systems was used to assess the timing of microbial methanogenesis contributing to gases in fracture water samples from three mines in the Witwatersrand Basin, South Africa. The results demonstrated that the majority of methane was produced over geologic timescales. In four of the samples, the methane contained no significant radiocarbon, indicating that the estimated 90% microbial methane in these samples was produced in the geologic past by indigenous microbial communities. In two samples from different mines, methane Δ14C levels indicated a primarily ancient origin for the microbial methane with the potential for more recent contributions from ongoing indigenous microbial activities constrained to between 0 and 40%, and 0 and 24%, respectively. Microbiological evidence for methanogenic archaea was observed in both of these samples. One sample had a Δ14C CH4 that was higher than the co...
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TL;DR: In experiments where liquid fractions from the soil simulant and water mixtures were used in place of the buffer, two out of three of the species demonstrated significantly greater methane production compared to the buffer.
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31 Mar 2006
TL;DR: In this article, a method for detecting a methanogen and an acid forming bacterium, which exist in the treated sludge obtained by subjecting organic waste, waste water or the like to methane fermentation and are related to methanation, was provided.
Abstract: PROBLEM TO BE SOLVED: To provide a method for detecting a methanogen and an acid forming bacterium, which exist in the treated sludge obtained by subjecting organic waste, waste water or the like to methane fermentation and are related to methanation, and evaluating the activity of the methanogen and consequently to provide an adequate operation management index of a methane fermentation apparatus and a method for controlling a process. SOLUTION: The method for controlling an anaerobic treatment process is characterized in that the ratio of a volatile organic acid forming rate to a methanation rate in a methane fermentation system is kept equal to or lower than 10.0. COPYRIGHT: (C)2008,JPO&INPIT
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TL;DR: Four methanogenic granules taken from an anaerobic reactor in different periods were investigated by FISH and DGGE and the eubacterial and archaeal community in these granules was researched and the phylogenetic analysis of dominant archaea was studied.
Abstract: Four methanogenic granules taken from an anaerobic reactor in different periods were investigated by FISH and DGGE, the eubacterial and archaeal community in these granules was researched and the phylogenetic analysis of dominant archaea was also studied. The FISH results indicated that the quantity of eubacteria was much more than archaea in the methanogenic granule and most eubacteria were located in the out layer of granule, while most archaea were located in the inner layer. The DGGE fingerprints indicated that as the organic loading rate of the reactor increased and the operating time elapsed, the eubacterial community was kept stable relatively, while the archaeal community was changed significantly, which resulted in the gradual decrease of the archaeal varieties. As seven typical bands were cut and sequenced, the results indicated that the dominant species of archaea in granule of the last period were Methanocor pusculum, Methanobacterium, Methanosaeta, and etc.
01 Jan 2006
TL;DR: Methane production potential showed that FACE promoted methane release, especially under UN condition, and methanotrophs activities under UN and HR conditions were restrained except at heading stage.
Abstract: A free-air CO2 enrichment (FACE) experiment was conducted during rice-growing season in 2005 in paddy fields at Jiangdu of Jiangsu province with two different N fertilization levels (Usual N - UN and Low N - LN) and two levels of rice-straw-returning-back-to-field (HR, NR) to evaluate population changes of methanogens and methanotrophs by the most-probable-number (MPN) method as well as methane production and oxidizing potential by gas chromatography. Results showed that elevated atmospheric CO2 concentrations increased methanogens population at tillering stage, but restrained methanogens activity at heading and harvest stages under HR condition. Rising atmospheric CO2 concentrations increased methanotrophs activity under LN condition, and methanotrophs population in FACE condition was significantly higher than that of Ambient in heading stage. But methanotrophs activities under UN and HR conditions were restrained except at heading stage. Methane production potential showed that FACE promoted methane release, especially under UN condition. High methane oxidizing activity was found under UN condition with enough exterior-CH4 and rising atmospheric CO2 concentrations.
16 Aug 2006
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12 Jan 2006
TL;DR: In this article, the authors proposed a technology for mass production of microbial protein, a biodegradable plastic and methane gas by using incomplete combustion gases of a dry biomass and an organic waste as raw materials and making good use of it as a substrate for methanogen.
Abstract: PROBLEM TO BE SOLVED: To provide a technology for mass producing three of microbial protein, a biodegradable plastic and methane gas by using incomplete combustion gases of a dry biomass and an organic waste as raw materials and making good use of it as a substrate for methanogen. SOLUTION: (1) A dry biomass such as lumber, etc., and an organic waste such as plastic, etc., are partially oxidized at a high temperature to give carbon monoxide gas, hydrogen gas and carbon dioxide gas, which are used as a substrate for methanogens to mass produce methanogens and to make a food and a feed (microbial protein) from microbial cells. (2) An organic waste is partially oxidized at a high temperature to give carbon monoxide gas, hydrogen gas, carbon dioxide gas, etc., which are used as a substrate for methanogens to produce a biodegradable plastic such as a poly-3-hydroxybutyric acid, etc. (3) An organic waste is partially oxidized at a high temperature to give carbon dioxide gas, hydrogen gas and carbon dioxide gas, which are used as a substrate for methanogens to mass produce methane gas. COPYRIGHT: (C)2007,JPO&INPIT