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1.
Environ Sci Pollut Res Int ; 26(34): 35131-35139, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31680200

RESUMO

Water column and sediment samples were collected in the southern Gulf of Mexico (GoMex) during 3 oceanographic cruises: XIXIMI-04 (September 2015), XIXIMI-05 (June 2016), and XIXIMI-06 (August 2017). DNA that was extracted from the samples was analyzed by qPCR to detect and quantify bacterial groups that have been reported to metabolize alkanes (Alcanivorax) and aromatic hydrocarbons (Cycloclasticus) and are involved in methane production (Methanomicrobiales). The results were then analyzed with regard to the water masses that are currently detected in the GoMex. Generally, we observed a decrease in the proportion of Alcanivorax and a rise in those of Cycloclasticus and Methanomicrobiales in samples from the surface to deep waters and in sediment samples. Scatterplots of the results showed that the relative abundance of the 3 groups was higher primarily from the surface to 1000 m, but the levels of Cycloclasticus and Methanomicrobiales were high in certain water samples below 1000 m and in sediments. In conclusion, oil-degrading bacteria are distributed widely from the surface to deep waters and sediments throughout the southern GoMex, representing a potential inoculum of bacteria for various hydrocarbon fractions that are ready for proliferation and degradation in the event of an oil spill from the seafloor or along the water column.


Assuntos
Biodegradação Ambiental , Sedimentos Geológicos/microbiologia , Microbiologia da Água , Alcanivoraceae , Alcanos/análise , Bactérias/metabolismo , Monitoramento Ambiental , Golfo do México , Hidrocarbonetos/análise , Methanomicrobiales , Petróleo/metabolismo , Poluição por Petróleo/análise , Poluentes Químicos da Água/análise
2.
Bioresour Technol ; 280: 158-164, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30771570

RESUMO

The applicability of a dynamic membrane (DM) was examined in the anaerobic treatment of high-strength food waste. A DM was established on woven polyester with a pore size of 50 µm, which achieved a solids retention time to hydraulic retention time ratio of 2.1:12.1. The highest average rate of methane production (1.1 L CH4/L/d) was achieved with an organic loading rate (OLR) of 5.0 g chemical oxygen demand (COD)/L/d. Propionate was the most abundant volatile fatty acid (VFA) for OLRs above 3.1 g/L/d, but concentrations were maintained below 0.9 g/L. Up to 82% of the VFAs in the mixed liquor was reduced in the effluent, implying high methanogenic activity of the DM. Microbial assays confirmed a higher archaeal and bacterial content in the DM than in the mixed liquor at shear velocities above 1.0 cm/s. Methanolinea tarda, which is known to be propionate tolerant, was the predominant archaea in the DM.


Assuntos
Reatores Biológicos , Alimentos , Microbiota , Anaerobiose , Análise da Demanda Biológica de Oxigênio , Euryarchaeota/metabolismo , Ácidos Graxos Voláteis/biossíntese , Metano/biossíntese , Methanomicrobiales/metabolismo
3.
Bioresour Technol ; 280: 1-8, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30743054

RESUMO

In-situ upgrading of biogas in a mesophilic anaerobic digester of sewage sludge by sparging H2 through a membrane was studied. Large gas recirculation rates were required to facilitate H2 transfer to the bulk liquid phase; at  ∼200 L Lreactor-1 d-1, H2 utilization efficiency averaged 94% and the specific CH4 production increased from 0.38 L Lreactor-1 d-1, during conventional digestion, to 0.54 L Lreactor-1 d-1. Sludge digestion was not compromised by elevated H2 partial pressure nor by the associated rise in the pH (8.1) because of CO2 removal. In this regard, VFA accumulation was not detected and the performance of VS removal was similar to the observed without H2 supply. Microbial analysis revealed that homoacetogens were outcompeted by hydrogenotrophic methanogens. Methanoculleus sp., Methanospirillum sp., Methanolinea sp. and Methanobacterium sp. were the hydrogenotrophic archaea present over the experiment.


Assuntos
Biocombustíveis , Hidrogênio/metabolismo , Esgotos/microbiologia , Anaerobiose , Reatores Biológicos/microbiologia , Methanomicrobiales/metabolismo
4.
Chemosphere ; 221: 81-88, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30634152

RESUMO

This study evaluated how tylosin (TYL), ciprofloxacin (CIP), and sulfadimidine (SM2) affected biogas and CH4 production during anaerobic digestion (AD) via their effects on the key genes related to methane production and the methanogenic community. The results showed that TYL, CIP, and SM2 reduced the production of methane during AD by 7.5%, 21.9%, and 16.0%, respectively. After AD for five days, CIP strongly inhibited the mcrA gene, where its abundance was 49% less than that in the control. TYL and SM2 decreased the abundances of Spirochaeta and Fibrobacteres during AD. High-throughput sequencing identified 10 methanogen genera, where Methanocorpusculum, Methanobrevibacter, and Methanosarcina accounted for 99.1% of the total archaeal reads. TYL and SM2 increased the efficiency of the acetoclastic methanogen pathway (Methanosarcina) by 29.04% and 52.79%, respectively. Redundancy analysis showed that Spirochaeta, Fibrobacteres, and Methanosarcina had positive correlations with CH4 and mcrA. We found that 30 mg kg-1 CIP had a strong inhibitory effect on methane production by influencing the abundances of Methanobrevibacter and Methanosarcina during AD.


Assuntos
Ciprofloxacino/farmacologia , Esterco/microbiologia , Metano/biossíntese , Methanomicrobiales/efeitos dos fármacos , Sulfametazina/farmacologia , Tilosina/farmacologia , Anaerobiose , Animais , Reatores Biológicos/microbiologia , Bovinos , Enzimas de Restrição do DNA/genética , Metano/metabolismo , Methanomicrobiales/metabolismo , Methanosarcinales/metabolismo
5.
J Dairy Sci ; 102(3): 2275-2282, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30692015

RESUMO

Rumen cannulation is a widely employed technique in ruminant nutrition research. However, the gap between skin and rumen cannula can cause leakage of fermentation gases and influx of atmospheric air, which may adversely affect the anaerobic environment in the rumen. The present study was designed to investigate the effects of rumen cannulation on headspace gases, dissolved gases, fermentation end products, and methanogen community in the rumen of dairy cows. Eight Holstein cows were used in the experiment. Four cows were surgically fitted with rumen cannulas, whereas the other 4 intact cows were used as control. Rumen cannulation decreased gaseous hydrogen and methane concentrations, dissolved carbon dioxide concentration, and relative abundances of Methanosphaera, and increased the saturation factor of dissolved hydrogen and dissolved methane, dissolved methane concentration, volatile fatty acid concentration, 16S ribosomal RNA gene copies of methanogens, and Simpson index of methanogen community. In summary, rumen cannulation causes a reduction in headspace gaseous hydrogen and gaseous methane, which may not decrease dissolved gas concentrations due to an increase in saturation factors. Furthermore, rumen cannulation alters methanogen community with increased methanogen population and decreased relative abundances of Methanosphaera.


Assuntos
Bovinos/microbiologia , Bovinos/fisiologia , Microbioma Gastrointestinal/fisiologia , Methanomicrobiales/fisiologia , Rúmen/microbiologia , Rúmen/fisiologia , Animais , Cateterismo/veterinária , Indústria de Laticínios , Feminino , Gases/metabolismo , Lactação , Metano/metabolismo
6.
J Environ Sci (China) ; 76: 238-248, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30528014

RESUMO

Anaerobic sludge from a sewage treatment plant was used to acclimatize microbial colonies capable of anaerobic oxidation of methane (AOM) coupled to sulfate reduction. Clone libraries and fluorescence in situ hybridization were used to investigate the microbial population. Sulfate-reducing bacteria (SRB) (e.g., Desulfotomaculum arcticum and Desulfobulbus propionicus) and anaerobic methanotrophic archaea (ANME) (e.g., Methanosaeta sp. and Methanolinea sp.) coexisted in the enrichment. The archaeal and bacterial cells were randomly or evenly distributed throughout the consortia. Accompanied by sulfate reduction, methane was oxidized anaerobically by the consortia of methane-oxidizing archaea and SRB. Moreover, CH4 and SO42- were consumed by methanotrophs and sulfate reducers with CO2 and H2S as products. The H3CSH produced by methanotrophy was an intermediate product during the process. The methanotrophic enrichment was inoculated in a down-flow biofilter for the treatment of methane and H2S from a landfill site. On average, 93.33% of H2S and 10.71% of methane was successfully reduced in the biofilter. This study tries to provide effective method for the synergistic treatment of waste gas containing sulfur compounds and CH4.


Assuntos
Sulfeto de Hidrogênio/isolamento & purificação , Sulfeto de Hidrogênio/metabolismo , Metano/isolamento & purificação , Metano/metabolismo , Anaerobiose , Biodegradação Ambiental , Deltaproteobacteria/metabolismo , Desulfotomaculum/metabolismo , Methanomicrobiales/metabolismo , Methanosarcinales/metabolismo , Oxirredução
7.
Biotechnol Adv ; 36(7): 1971-1983, 2018 11 15.
Artigo em Inglês | MEDLINE | ID: mdl-30144516

RESUMO

Exposure of a small amount of oxygen/air (microaeration) has been reported to benefit the anaerobic digestion (AD) process in enhancing hydrolysis, improving methane yield, stabilizing the process and scavenging hydrogen sulfide among others. The underlying mechanism of enhancing AD process via microaeration is the augmentation of activity and diversity of the microbial consortia that promotes syntrophic interactions among different microbial groups, thereby creating a more stable process. To design and implement a microaeration-based AD process, fundamental insights about the mechanism of the AD system at process, microbial and molecular levels must be fully explored. This review critically examines microaeration-based AD processes through our recent understandings of the effect of oxygen on microbial community structure, enzymatic, energetic, physiological, and biochemical aspects of the microbial-mediated process. Syntrophic interactions between hydrolytic, fermentative, sulfate reducing, syntrophic bacteria and methanogens under microaerobic conditions are examined to reveal putative mechanism and factors that need to be considered when implementing microaeration in AD process. Further studies are needed to better understand the microbial pathways and bioenergetics of the microaerobic AD process by adopting advanced molecular techniques such as metagenomics, transcriptomics, and proteomics.


Assuntos
Bactérias/metabolismo , Sulfeto de Hidrogênio/metabolismo , Metano/metabolismo , Methanomicrobiales/metabolismo , Consórcios Microbianos/fisiologia , Oxigênio/metabolismo , Anaerobiose , Reatores Biológicos , Fermentação , Perfilação da Expressão Gênica , Hidrólise , Redes e Vias Metabólicas , Metagenômica , Oxirredução , Proteômica
8.
Extremophiles ; 22(3): 447-459, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29429010

RESUMO

Permafrost thaw can bring negative consequences in terms of ecosystems, resulting in permafrost collapse, waterlogging, thermokarst lake development, and species composition changes. Little is known about how permafrost thaw influences microbial community shifts and their activities. Here, we show that the dominant archaeal community shifts from Methanomicrobiales to Methanosarcinales in response to the permafrost thaw, and the increase in methane emission is found to be associated with the methanogenic archaea, which rapidly bloom with nearly tenfold increase in total number. The mcrA gene clone libraries analyses indicate that Methanocellales/Rice Cluster I was predominant both in the original permafrost and in the thawed permafrost. However, only species belonging to Methanosarcinales showed higher transcriptional activities in the thawed permafrost, indicating a shift of methanogens from hydrogenotrophic to partly acetoclastic methane-generating metabolic processes. In addition, data also show the soil texture and features change as a result of microbial reproduction and activity induced by this permafrost thaw. Those data indicate that microbial ecology under warming permafrost has potential impacts on ecosystem and methane emissions.


Assuntos
Efeito Estufa , Metano/metabolismo , Methanomicrobiales/metabolismo , Methanosarcinales/metabolismo , Pergelissolo/microbiologia , Proteínas Arqueais/genética , Proteínas Arqueais/metabolismo , Methanomicrobiales/crescimento & desenvolvimento , Methanosarcinales/crescimento & desenvolvimento , Microbiota
9.
Water Res ; 130: 376-387, 2018 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-29258049

RESUMO

The effect of chitosan on the development of granular sludge in upflow anaerobic sludge blanket reactors (UASB) when treating wastewater polluted with the organic solvents ethanol, ethyl acetate, and 1-ethoxy-2-propanol was evaluated. Three UASB reactors were operated for 219 days at ambient temperature with an organic loading rate (OLR) of between 0.3 kg COD m-3 d-1 and 20 kg COD m-3 d-1. One reactor was operated without the addition of chitosan, while the other two were operated with the addition of chitosan doses of 2.4 mg gVSS-1 two times. The three reactors were all able to treat the OLR tested with COD removal efficiencies greater than 90%. However, the time required to reach stable operation was considerably reduced in the chitosan-assisted reactors. The development of granules in the reactors with chitosan was accelerated and granules larger than 2000 µm were only observed in these reactors. In addition, these granules exhibited better physicochemical characteristics: the mean particle diameter (540 and 613 µm) was approximately two times greater than in the control reactor (300 µm), and the settling velocities exceeded 35 m h-1. The extracellular polymeric substances (EPS) in the reactors with the chitosan was found to be higher than in the control reactor. The protein-EPS content has been correlated with the granule size. The analyses of the microbial communities, performed through denaturing gradient gel electrophoresis and high-throughput sequencing, revealed that the syntrophic microorganisms belonging to genus Geobacter and the hydrogenotrophic methanogen Methanocorpusculum labreanum were predominant in the granules. Other methanogens like Methanosaeta species were found earlier in the chitosan-assisted reactors than in the control reactor.


Assuntos
Reatores Biológicos/microbiologia , Quitosana , Solventes , Eliminação de Resíduos Líquidos/métodos , Anaerobiose , Análise da Demanda Biológica de Oxigênio , Geobacter/metabolismo , Methanomicrobiales/metabolismo , Microbiota/genética , Microbiota/fisiologia , Tamanho da Partícula , Polímeros , Esgotos , Eliminação de Resíduos Líquidos/instrumentação , Águas Residuárias/química , Poluentes Químicos da Água
10.
Microb Ecol ; 75(3): 811-818, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29018917

RESUMO

The red macroalga Asparagopsis taxiformis has been shown to significantly decrease methane production by rumen microbial communities. This has been attributed to the bioaccumulation of halogenated methane analogues produced as algal secondary metabolites. The objective of this study was to evaluate the impact of A. taxiformis supplementation on the relative abundance of methanogens and microbial community structure during in vitro batch fermentation. Addition of A. taxiformis (2% organic matter) or the halogenated methane analogue bromoform (5 µM) reduced methane production by over 99% compared to a basal substrate-only control. Quantitative PCR confirmed that the decrease in methane production was correlated with a decrease in the relative abundance of methanogens. High-throughput 16S ribosomal RNA gene amplicon sequencing showed that both treatments reduced the abundance of the three main orders of methanogens present in ruminants (Methanobacteriales, Methanomassiliicoccales and Methanomicrobiales). Shifts in bacterial community structure due to the addition of A. taxiformis and 5 µM bromoform were similar and concomitant with increases in hydrogen concentration in the headspace of the fermenters. With high potency and broad-spectrum activity against rumen methanogens, A. taxiformis represents a promising natural strategy for reducing enteric methane emissions from ruminant livestock.


Assuntos
Metano/análogos & derivados , Microbiota/efeitos dos fármacos , Rodófitas/metabolismo , Rúmen/microbiologia , Alga Marinha/metabolismo , Animais , Bactérias/classificação , Bactérias/efeitos dos fármacos , Bactérias/metabolismo , DNA Bacteriano/genética , Fermentação , Halogenação , Hidrogênio/metabolismo , Técnicas In Vitro , Gado/microbiologia , Metano/metabolismo , Methanobacteriales/efeitos dos fármacos , Methanobacteriales/metabolismo , Methanomicrobiales/efeitos dos fármacos , Methanomicrobiales/metabolismo , Microbiota/genética , RNA Ribossômico 16S/genética , Trialometanos/farmacologia
11.
J Microbiol ; 55(11): 862-870, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-29076069

RESUMO

Minerals that contain ferric iron, such as amorphous Fe(III) oxides (A), can inhibit methanogenesis by competitively accepting electrons. In contrast, ferric iron reduced products, such as magnetite (M), can function as electrical conductors to stimulate methanogenesis, however, the processes and effects of magnetite production and transformation in the methanogenic consortia are not yet known. Here we compare the effects on methanogenesis of amorphous Fe (III) oxides (A) and magnetite (M) with ethanol as the electron donor. RNA-based terminal restriction fragment length polymorphism with a clone library was used to analyse both bacterial and archaeal communities. Iron (III)-reducing bacteria including Geobacteraceae and methanogens such as Methanosarcina were enriched in iron oxide-supplemented enrichment cultures for two generations with ethanol as the electron donor. The enrichment cultures with A and non-Fe (N) dominated by the active bacteria belong to Veillonellaceae, and archaea belong to Methanoregulaceae and Methanobacteriaceae, Methanosarcinaceae (Methanosarcina mazei), respectively. While the enrichment cultures with M, dominated by the archaea belong to Methanosarcinaceae (Methanosarcina barkeri). The results also showed that methanogenesis was accelerated in the transferred cultures with ethanol as the electron donor during magnetite production from A reduction. Powder X-ray diffraction analysis indicated that magnetite was generated from microbial reduction of A and M was transformed into siderite and vivianite with ethanol as the electron donor. Our data showed the processes and effects of magnetite production and transformation in the methanogenic consortia, suggesting that significantly different effects of iron minerals on microbial methanogenesis in the iron-rich coastal riverine environment were present.


Assuntos
Óxido Ferroso-Férrico/metabolismo , Sedimentos Geológicos/microbiologia , Metano/metabolismo , Methanomicrobiales/metabolismo , Consórcios Microbianos/fisiologia , Rios/microbiologia , Anaerobiose , Compostos Férricos/metabolismo , Compostos Férricos/farmacologia , Geobacter/efeitos dos fármacos , Geobacter/metabolismo , Ferro/metabolismo , Methanomicrobiales/efeitos dos fármacos , Methanosarcina/efeitos dos fármacos , Methanosarcina/metabolismo , RNA Ribossômico 16S/genética
12.
Astrobiology ; 17(10): 1053-1066, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28949766

RESUMO

As many of the methanogens first encountered at hydrothermal vents were thermophilic to hyperthermophilic and comprised one of the lower roots of the evolutionary tree, it has been assumed that methanogenesis was one of the earliest, if not the earliest, pathway to life. It being well known that hydrothermal springs associated with serpentinization also bore abiotic methane, it had been further assumed that emergent biochemistry merely adopted and quickened this supposed serpentinization reaction. Yet, recent hydrothermal experiments simulating serpentinization have failed to generate methane so far, thus casting doubt on this assumption. The idea that the inverse view is worthy of debate, that is, that methanotrophy was the earlier, is stymied by the "fact" that methanotrophy itself has been termed "reverse methanogenesis," so allotting the methanogens the founding pedigree. Thus, attempting to suggest instead that methanogenesis might be termed reverse methanotrophy would require "unlearning"-a challenge to the subconscious! Here we re-examine the "impossibility" of methanotrophy predating methanogenesis as in what we have termed the "denitrifying methanotrophic acetogenic pathway." Advantages offered by such thinking are that methane would not only be a fuel but also a ready source of reduced carbon to combine with formate or carbon monoxide-available in hydrothermal fluids-to generate acetate, a target molecule of the first autotrophs. And the nitrate/nitrite required for the putative oxidation of methane with activated NO would also be a ready source of fixed nitrogen for amination reactions. Theoretical conditions for such a putative pathway would be met in a hydrothermal green rust-bearing exhalative pile and associated chimneys subject to proton and electron counter gradients. This hypothesis could be put to test in a high-pressure hydrothermal reaction chamber in which a cool carbonate/nitrate/nitrite-bearing early acidulous ocean simulant is juxtaposed across a precipitate membrane to an alkaline solution of hydrogen and methane. Key Words: Green rust-Methanotrophy-Nitrate reduction-Emergence of life. Astrobiology 17, 1053-1066.


Assuntos
Exobiologia/métodos , Fontes Hidrotermais/microbiologia , Metano/biossíntese , Methanomicrobiales/metabolismo , Origem da Vida , Monóxido de Carbono/química , Hidrogênio/química , Fontes Hidrotermais/química , Metano/química , Nitratos/química , Nitritos/química , Oxirredução
13.
J Appl Microbiol ; 123(4): 933-943, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28736977

RESUMO

AIMS: Pit mud is essential for the quality and yield of Chinese Luzhou-flavoured liquor. A reliable and fast method based on the use of microbial indicators combined with environmental factors coupled with metrology tools is needed to discriminate and classify different maturity levels of Luzhou-flavoured pit muds. METHODS AND RESULTS: Firmicutes, Bacteroidetes, Actinobacteria, Lactobacillus, Bacillus, Methanosarcina, Methanocorpusculum, Methanoculleus and Clostridium kluyveri were microbial indicators in Luzhou-flavoured pit muds. They were detected by real-time quantitative PCR. Environmental factors investigated included moisture content, pH, total acid and ammonia nitrogen. Principal component analysis (PCA) and partial least square-discriminant analysis were employed to explore the structure of the data and construct discrimination and classification models by reduction in the data dimensionality. Pit muds were distinguished and classified as new, trend to-be aged and aged. Moisture content and pH were significantly negatively correlated with new pit mud, while pH, total acid, amino nitrogen, Firmicutes, Bacteroidetes, Actinobacteria, Methanosarcina, Methanoculleus and C. kluyveri were significantly positively correlated with aged pit mud. CONCLUSIONS: Microbial indicators combined with environmental factors coupled to metrology tools can reliably and quickly discriminate and classify different maturity levels of Luzhou-flavoured pit muds. SIGNIFICANCE AND IMPACT OF THE STUDY: Modern techniques and metrology tools verified the correctness of the traditional sensory evaluation used in controlling the quality of pit mud, and will contribute to distinguishing different maturity levels of Chinese Luzhou-flavoured pit muds.


Assuntos
Bebidas Alcoólicas/microbiologia , Fermentação , Actinobacteria/genética , Actinobacteria/isolamento & purificação , Actinobacteria/metabolismo , Bacillus/genética , Bacillus/isolamento & purificação , Bacillus/metabolismo , Bacteroidetes/genética , Bacteroidetes/isolamento & purificação , Bacteroidetes/metabolismo , Firmicutes/genética , Firmicutes/isolamento & purificação , Firmicutes/metabolismo , Aromatizantes , Humanos , Concentração de Íons de Hidrogênio , Lactobacillus/genética , Lactobacillus/isolamento & purificação , Lactobacillus/metabolismo , Methanomicrobiaceae/genética , Methanomicrobiaceae/isolamento & purificação , Methanomicrobiaceae/metabolismo , Methanomicrobiales/genética , Methanomicrobiales/isolamento & purificação , Methanomicrobiales/metabolismo , Methanosarcina/genética , Methanosarcina/isolamento & purificação , Methanosarcina/metabolismo , Paladar
14.
Microb Ecol ; 74(1): 6-9, 2017 07.
Artigo em Inglês | MEDLINE | ID: mdl-28070677

RESUMO

The Watson River drains a portion of the SW Greenland ice sheet, transporting microbial communities from subglacial environments to a delta at the head of Søndre Strømfjord. This study investigates the potential activity and community shifts of glacial microbiota deposited and buried under layers of sediments within the river delta. A long-term (12-month) incubation experiment was established using Watson River delta sediment under anaerobic conditions, with and without CO2/H2 enrichment. Within CO2/H2-amended incubations, sulphate depletion and a shift in the microbial community to a 52% predominance of Desulfosporosinus meridiei by day 371 provides evidence for sulphate reduction. We found evidence of methanogenesis in CO2/H2-amended incubations within the first 5 months, with production rates of ~4 pmol g-1 d-1, which was likely performed by methanogenic Methanomicrobiales- and Methanosarcinales-related organisms. Later, a reduction in methane was observed to be paired with the depletion of sulphate, and we hypothesise that sulphate reduction out competed hydrogenotrophic methanogenesis. The structure and diversity of the original CO2/H2-amended incubation communities changed dramatically with a major shift in predominant community members and a decline in diversity and cell abundance. These results highlight the need for further investigations into the fate of subglacial microbiota within downstream environments.


Assuntos
Sedimentos Geológicos/microbiologia , Camada de Gelo/microbiologia , Microbiota , Rios/microbiologia , Groenlândia , Metano , Methanomicrobiales , Methanosarcinales , Peptococcaceae , Sulfatos
15.
Appl Biochem Biotechnol ; 181(1): 91-111, 2017 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-27465037

RESUMO

Silage and dry are the two typical cornstalk forms. Either form could be used as substrate in biogas plants and might be replaced by another when shortage occurred. This study focused on the feeding sequence of these two kinds of feedstocks, aiming to discuss their specific methane potential (SMP). A 15-day hydraulic retention time was chosen for semi-continuous experiments based on the batch test results. In semi-continuous experiments, before and after feedstocks were exchanged, the significantly decreased and comparable SMPs of silage and dry cornstalks indicated that a basis of unstable digestion would result in incomplete methane release from the subsequent digestion. A higher similarity of bacterial community structure and greater quantity of bacteria were shown in acidified silage cornstalk digestion through band similarity analysis. Methanosaetaceae and methanomicrobiales were the predominant methanogens, and aceticlastic methanogenesis was the main route for methane production. The different feeding sequences affected the hydrolysis course and further influenced the methanogenic proliferation. Our work suggests that silage cornstalk digestion should be conducted before dry cornstalk digestion.


Assuntos
Metano/metabolismo , Methanomicrobiales/metabolismo , Methanosarcinales/metabolismo , Zea mays/metabolismo , Anaerobiose , Hidrólise , Metano/biossíntese , Metano/química , Methanomicrobiales/química , Methanosarcinales/química , Silagem , Especificidade por Substrato , Zea mays/química
16.
ISME J ; 11(1): 87-99, 2017 01.
Artigo em Inglês | MEDLINE | ID: mdl-27552639

RESUMO

Members of the order Methanomicrobiales are abundant, and sometimes dominant, hydrogenotrophic (H2-CO2 utilizing) methanoarchaea in a broad range of anoxic habitats. Despite their key roles in greenhouse gas emissions and waste conversion to methane, little is known about the physiological and genomic bases for their widespread distribution and abundance. In this study, we compared the genomes of nine diverse Methanomicrobiales strains, examined their pangenomes, reconstructed gene flow and identified genes putatively mediating their success across different habitats. Most strains slowly increased gene content whereas one, Methanocorpusculum labreanum, evidenced genome downsizing. Peat-dwelling Methanomicrobiales showed adaptations centered on improved transport of scarce inorganic nutrients and likely use H+ rather than Na+ transmembrane chemiosmotic gradients during energy conservation. In contrast, other Methanomicrobiales show the potential to concurrently use Na+ and H+ chemiosmotic gradients. Analyses also revealed that the Methanomicrobiales lack a canonical electron bifurcation system (MvhABGD) known to produce low potential electrons in other orders of hydrogenotrophic methanogens. Additional putative differences in anabolic metabolism suggest that the dynamics of interspecies electron transfer from Methanomicrobiales syntrophic partners can also differ considerably. Altogether, these findings suggest profound differences in electron trafficking in the Methanomicrobiales compared with other hydrogenotrophs, and warrant further functional evaluations.


Assuntos
Genoma Arqueal , Methanomicrobiales/genética , Aclimatação , Adaptação Fisiológica , Ecossistema , Genômica , Metano/metabolismo , Methanomicrobiales/classificação , Methanomicrobiales/isolamento & purificação , Methanomicrobiales/fisiologia , Filogenia , Solo , Microbiologia do Solo
17.
J Microbiol ; 54(12): 814-822, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27888460

RESUMO

We have previously identified a sulfate methane transition zone (SMTZ) within the methane hydrate-bearing sediment in the Ulleung Basin, East Sea of Korea, and the presence of ANME-1b group in the sediment has been shown by phylogenetic analysis of a 16S rRNA gene. Herein, we describe taxonomic and functional profiling in the SMTZ sample by metagenomic analysis, comparing with that of surface sediment. Metagenomic sequences of 115 Mbp and 252 Mbp were obtained from SMTZ and surface sediments, respectively. The taxonomic profiling using BLASTX against the SEED within MG-RAST showed the prevalence of methanogens (19.1%), such as Methanosarcinales (12.0%) and Methanomicrobiales (4.1%) predominated within the SMTZ metagenome. A number of 185,200 SMTZ reads (38.9%) and 438,484 surface reads (62.5%) were assigned to functional categories, and methanogenesis-related reads were statistically significantly overrepresented in the SMTZ metagenome. However, the mapping analysis of metagenome reads to the reference genomes, most of the sequences of the SMTZ metagenome were mapped to ANME-1 draft genomes, rather than those of methanogens. Furthermore, the two copies of the methyl-coenzyme M reductase gene (mcrA) segments of the SMTZ metagenome were clustered with ANME-1b in the phylogenetic cluster. These results indicate that ANME-1b reads were miss-annotated to methanogens due to limitation of database. Many of key genes necessary for reverse methanogenesis were present in the SMTZ metagenome, except for N 5,N 10-methenyl-H4MPT reductase (mer) and CoB-CoM heterodisulfide reductase subunits D and E (hdrDE). These data suggest that the ANME-1b represents the primary player the anaerobic methane oxidation in the SMTZ, of the methane hydrate-bearing sediment at the Ulleung Basin, East Sea of Korea.


Assuntos
Archaea/genética , Euryarchaeota/genética , Euryarchaeota/metabolismo , Metagenoma , Metagenômica , Metano/metabolismo , Anaerobiose , Archaea/classificação , Archaea/isolamento & purificação , DNA Arqueal/genética , Euryarchaeota/classificação , Euryarchaeota/isolamento & purificação , Sedimentos Geológicos/microbiologia , Methanomicrobiales/genética , Methanomicrobiales/isolamento & purificação , Methanomicrobiales/metabolismo , Methanosarcinales/genética , Methanosarcinales/isolamento & purificação , Methanosarcinales/metabolismo , Oceanos e Mares , Oxirredução , Filogenia , RNA Ribossômico 16S , República da Coreia
18.
Int J Syst Evol Microbiol ; 66(11): 4900-4904, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27499051

RESUMO

A recent Request for an Opinion has raised the issue of the inter-relationship between Methanocorpusculum parvum Zellner et al. 1988, the type species of the genus Methanocorpusculum Zellner et al. 1988 as defined at the time of valid publication of the genus name and the subsequent recognition of Methanocorpusculum aggregans (Ollivier et al., 1985) Xun et al.1989 as an earlier heterotypic synonym. Examination of the relevant literature indicates that there are a number of misunderstandings that have arisen. In particular misinterpretation of Rule 15 of the International Code of Nomenclature of Prokaryotes continues to be a source of confusion. Additional problems centre on whether the nomenclatural type of a taxon continues to be the nomenclatural type even if that name is not treated as the correct name and would not appear in a list of names in a given classification. It would be appropriate to clarify these issues.


Assuntos
Methanomicrobiales/classificação , Filogenia , Terminologia como Assunto
19.
Bioresour Technol ; 218: 796-806, 2016 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27423547

RESUMO

For evaluating the methanogenesis from typical methanogenic precursors (formate, acetate and H2/CO2), CH4 production kinetics were investigated at 37±1°C in batch anaerobic digestion tests and stimulated by modified Gompertz model. The results showed that maximum methanation rate from formate, acetate and H2/CO2 were 19.58±0.49, 42.65±1.17 and 314.64±3.58NmL/gVS/d in digested manure system and 6.53±0.31, 132.04±3.96 and 640.16±19.92NmL/gVS/d in sewage sludge system during second generation incubation. Meanwhile the model could not fit well in granular sludge system, while the rate of formate methanation was faster than from H2/CO2 and acetate. Considering both the kinetic results and microbial assay we could conclude that H2/CO2 methanation was the fastest methanogenic step in digested manure and sewage sludge system with Methanomicrobiales as dominant methanogens, while granular sludge with Methanobacteriales as dominant methanogens contributed to the fastest formate methanation.


Assuntos
Acetatos , Formiatos , Metano , Acetatos/química , Acetatos/metabolismo , Reatores Biológicos/microbiologia , Dióxido de Carbono/química , Dióxido de Carbono/metabolismo , Formiatos/química , Formiatos/metabolismo , Hidrogênio/química , Hidrogênio/metabolismo , Cinética , Metano/análise , Metano/química , Metano/metabolismo , Methanomicrobiales/química , Methanomicrobiales/metabolismo , Esgotos/microbiologia
20.
Chemosphere ; 161: 53-60, 2016 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27421101

RESUMO

In this study, a fed-batch acidogenic reactor was operated at a 3 d hydraulic retention time (HRT) and fed with alkaline pre-treated sludge to investigate salinity effects on methanogens' abundance, activities and their consumption of produced acetic acid (HAc) and total volatile fatty acids (VFAs). The salinity concentration was increased step-wise by adding sodium chloride. At 3‰ (parts per thousand) salinity, the average produced volatile fatty acids (VFAs) concentration was 2410.16 ± 637.62 mg COD L(-1) and 2.70 ± 0.36 L methane was produced daily in the acidogenic reactor. Further batch tests indicated methanogens showed a HAc degradation rate of 3.81 mg COD g(-1) VSS h(-1) at initial HAc concentration of 1150 mg COD L(-1), and showed tolerance up to 16‰ salinity (3.76 g Na(+) L(-1)) as indicated by a constant HAc degradation rate. The microbiological study indicated this can be related to the predominance of acetate-utilizing Methanosarcinaceae and Methanomicrobiales in the reactor. However, with salinity increased to 20‰ and 40‰, increases in VFAs and HAc production and decreases in methane production, methanogens population, acidogenic bacteria population and acidification extent were observed. This study demonstrated presence of acetate-utilizing methanogens in an acidogenic reactor and their high tolerance to salinity, as well as their negative impacts on net VFAs production. The results would suggest the presence of methanogens in the acidogenic reactor should not be ignored and the recovery of methane from the acidogenic reactor needs to be considered to avoid carbon loss.


Assuntos
Ácido Acético/análise , Reatores Biológicos/microbiologia , Methanomicrobiales/crescimento & desenvolvimento , Esgotos/microbiologia , Purificação da Água/métodos , Anaerobiose , Carbono/análise , Carbono/metabolismo , Ácidos Graxos Voláteis/análise , Concentração de Íons de Hidrogênio , Metano/análise , Metano/metabolismo , Salinidade , Esgotos/química
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