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1.
Water Res ; 223: 118993, 2022 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-36007401

RESUMO

A better understanding of the interaction between nanoplastics and archaea is crucial to fill the knowledge gaps regarding the ecological safety of nanoplastics. As a vital source for global methane emissions, methanogenic archaea have unique cell membranes that are distinctly different from those in all other forms of life, little is known about their interaction with nanoplastics. Here, we show that polystyrene nanoparticles functionalized with sulfonic acid (PS-SO3H) and amino (PS-NH2) interact with this methanogenic archaeon in distinct ways. Although both of them have no significant phenotype effects on Methanosarcina acetivorans C2A, these nanoparticles could affect DNA-mediated transposition of this methanogenic archaeon, and PS-SO3H also downregulated nitrogen fixation, nitrogen cycle metabolic process, oxidoreductase activity, etc. In addition, both nanoplastics decreased the protein contents in the extracellular polymer substances (EPS), with distinct binding sequences to the functional groups of the EPS. The single particle atomic force microscopy revealed that the force between the amino group and the M. acetivorans C2A was greater than that of sulfonic acid group. Our results exhibit that the surface groups of polystyrene nanoparticles control their risk on the methanogenic archaea, and these effects might influence their contribution on global methane emission.


Assuntos
Methanosarcina , Nanopartículas , DNA/metabolismo , Metano/metabolismo , Methanomicrobiales/metabolismo , Methanosarcina/genética , Microplásticos , Nitrogênio/metabolismo , Oxirredutases , Poliestirenos , Ácidos Sulfônicos/metabolismo
2.
Viruses ; 13(10)2021 09 26.
Artigo em Inglês | MEDLINE | ID: mdl-34696364

RESUMO

Today, the number of known viruses infecting methanogenic archaea is limited. Here, we report on a novel lytic virus, designated Blf4, and its host strain Methanoculleus bourgensis E02.3, a methanogenic archaeon belonging to the Methanomicrobiales, both isolated from a commercial biogas plant in Germany. The virus consists of an icosahedral head 60 nm in diameter and a long non-contractile tail of 125 nm in length, which is consistent with the new isolate belonging to the Siphoviridae family. Electron microscopy revealed that Blf4 attaches to the vegetative cells of M. bourgensis E02.3 as well as to cellular appendages. Apart from M. bourgensis E02.3, none of the tested Methanoculleus strains were lysed by Blf4, indicating a narrow host range. The complete 37 kb dsDNA genome of Blf4 contains 63 open reading frames (ORFs), all organized in the same transcriptional direction. For most of the ORFs, potential functions were predicted. In addition, the genome of the host M. bourgensis E02.3 was sequenced and assembled, resulting in a 2.6 Mbp draft genome consisting of nine contigs. All genes required for a hydrogenotrophic lifestyle were predicted. A CRISPR/Cas system (type I-U) was identified with six spacers directed against Blf4, indicating that this defense system might not be very efficient in fending off invading Blf4 virus.


Assuntos
Vírus de Archaea/genética , Vírus de Archaea/metabolismo , Methanomicrobiaceae/virologia , Archaea/virologia , Vírus de Archaea/classificação , Sequência de Bases/genética , Genoma Viral/genética , Especificidade de Hospedeiro/genética , Methanomicrobiaceae/genética , Methanomicrobiaceae/metabolismo , Methanomicrobiales/genética , Methanomicrobiales/virologia , Filogenia , Análise de Sequência de DNA/métodos , Vírus/genética
3.
PLoS One ; 16(8): e0256048, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34379691

RESUMO

An in vivo study was conducted to compare the enteric methane emissions and diversity of ruminal methanogens in cattle and buffaloes kept in the same environment and fed on the same diet. Six cattle and six buffaloes were fed on a similar diet comprising Napier (Pennisetum purpureum) green grass and concentrate in 70:30. After 90 days of feeding, the daily enteric methane emissions were quantified by using the SF6 technique and ruminal fluid samples from animals were collected for the diversity analysis. The daily enteric methane emissions were significantly greater in cattle as compared to buffaloes; however, methane yields were not different between the two species. Methanogens were ranked at different taxonomic levels against the Rumen and Intestinal Methanogen-Database. The archaeal communities in both host species were dominated by the phylum Euryarchaeota; however, Crenarchaeota represented <1% of the total archaea. Methanogens affiliated with Methanobacteriales were most prominent and their proportion did not differ between the two hosts. Methanomicrobiales and Methanomassillicoccales constituted the second largest group of methanogens in cattle and buffaloes, respectively. Methanocellales (Methanocella arvoryza) were exclusively detected in the buffaloes. At the species level, Methanobrevibacter gottschalkii had the highest abundance (55-57%) in both the host species. The relative abundance of Methanobrevibacter wolinii between the two hosts differed significantly. Methanosarcinales, the acetoclastic methanogens were significantly greater in cattle than the buffaloes. It is concluded that the ruminal methane yield in cattle and buffaloes fed on the same diet did not differ. With the diet used in this study, there was a limited influence (<3.5%) of the host on the structure of the ruminal archaea community at the species level. Therefore, the methane mitigation strategies developed in either of the hosts should be effective in the other. Further studies are warranted to reveal the conjunctive effect of diet and geographical locations with the host on ruminal archaea community composition.


Assuntos
DNA Arqueal/genética , Dieta/veterinária , Metano/metabolismo , Methanomicrobiales/classificação , Methanomicrobiales/isolamento & purificação , Rúmen/metabolismo , Animais , Búfalos , Bovinos , DNA Arqueal/análise , Masculino , Metano/análise , Methanomicrobiales/genética , Methanomicrobiales/metabolismo , Rúmen/microbiologia
4.
PLoS One ; 16(1): e0244755, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33395690

RESUMO

The obstacle to optimal utilization of biogas technology is poor understanding of biogas microbiomes diversities over a wide geographical coverage. We performed random shotgun sequencing on twelve environmental samples. Randomized complete block design was utilized to assign the twelve treatments to four blocks, within eastern and central regions of Kenya. We obtained 42 million paired-end reads that were annotated against sixteen reference databases using two ENVO ontologies, prior to ß-diversity studies. We identified 37 phyla, 65 classes and 132 orders. Bacteria dominated and comprised 28 phyla, 42 classes and 92 orders, conveying substrate's versatility in the treatments. Though, Fungi and Archaea comprised 5 phyla, the Fungi were richer; suggesting the importance of hydrolysis and fermentation in biogas production. High ß-diversity within the taxa was largely linked to communities' metabolic capabilities. Clostridiales and Bacteroidales, the most prevalent guilds, metabolize organic macromolecules. The identified Cytophagales, Alteromonadales, Flavobacteriales, Fusobacteriales, Deferribacterales, Elusimicrobiales, Chlamydiales, Synergistales to mention but few, also catabolize macromolecules into smaller substrates to conserve energy. Furthermore, δ-Proteobacteria, Gloeobacteria and Clostridia affiliates syntrophically regulate PH2 and reduce metal to provide reducing equivalents. Methanomicrobiales and other Methanomicrobia species were the most prevalence Archaea, converting formate, CO2(g), acetate and methylated substrates into CH4(g). Thermococci, Thermoplasmata and Thermoprotei were among the sulfur and other metal reducing Archaea that contributed to redox balancing and other metabolism within treatments. Eukaryotes, mainly fungi were the least abundant guild, comprising largely Ascomycota and Basidiomycota species. Chytridiomycetes, Blastocladiomycetes and Mortierellomycetes were among the rare species, suggesting their metabolic and substrates limitations. Generally, we observed that environmental and treatment perturbations influenced communities' abundance, ß-diversity and reactor performance largely through stochastic effect. Understanding diversity of biogas microbiomes over wide environmental variables and its' productivity provided insights into better management strategies that ameliorate biochemical limitations to effective biogas production.


Assuntos
Biocombustíveis/microbiologia , Metagenômica/métodos , Microbiota/genética , Archaea/genética , Bactérias/genética , Bactérias Anaeróbias/genética , Bactérias Anaeróbias/metabolismo , Biodiversidade , Reatores Biológicos/microbiologia , Euryarchaeota/metabolismo , Fermentação , Fungos/genética , Quênia , Metano/metabolismo , Methanomicrobiales/metabolismo , Microbiota/fisiologia , Filogenia , RNA Ribossômico 16S
5.
Appl Environ Microbiol ; 87(6)2021 02 26.
Artigo em Inglês | MEDLINE | ID: mdl-33361366

RESUMO

Hydrogenotrophic methanogens produce CH4 using H2 as an electron donor to reduce CO2 In the absence of H2, many are able to use formate or alcohols as alternate electron donors. Methanogens from the order Methanomicrobiales are capable of growth with H2, but many lack genes encoding hydrogenases that are typically found in other hydrogenotrophic methanogens. In an effort to better understand electron flow in methanogens from the Methanomicrobiales, we undertook a genetic and biochemical study of heterodisulfide reductase (Hdr) in Methanoculleus thermophilus Hdr catalyzes an essential reaction by coupling the first and last steps of methanogenesis through flavin-based electron bifurcation. Hdr from M. thermophilus copurified with formate dehydrogenase (Fdh) and only displayed activity when formate was supplied as an electron donor. We found no evidence of an Hdr-associated hydrogenase, and H2 could not function as an electron donor, even with Hdr purified from cells grown on H2 We found that cells catalyze a formate hydrogenlyase activity that is likely essential for generating the formate needed for the Hdr reaction. Together, these results highlight the importance of formate as an electron donor for methanogenesis and suggest the ability to use formate is closely integrated into the methanogenic pathway in organisms from the order MethanomicrobialesIMPORTANCE Methanogens from the order Methanomicrobiales are thought to prefer H2 as an electron donor for growth. They are ubiquitous in anaerobic environments, such as in wastewater treatment facilities, anaerobic digesters, and the rumen, where they catalyze the terminal steps in the breakdown of organic matter. However, despite their importance, the metabolism of these organisms remains understudied. Using a genetic and biochemical approach, we show that formate metabolism is closely integrated into methanogenesis in Methanoculleus thermophilus This is due to a requirement for formate as the electron donor to heterodisulfide reductase (Hdr), an enzyme responsible for catalyzing essential reactions in methanogenesis by linking the initial CO2 fixing step to the exergonic terminal reaction of the pathway. These results suggest that hydrogen is not necessarily the preferred electron donor for all hydrogenotrophic methanogens and provide insight into the metabolism of methanogens from the order Methanomicrobiales.


Assuntos
Formiatos/metabolismo , Methanomicrobiales , Oxirredutases , Methanomicrobiales/genética , Methanomicrobiales/crescimento & desenvolvimento , Methanomicrobiales/metabolismo , Oxirredução , Oxirredutases/genética , Oxirredutases/metabolismo
6.
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
7.
J Equine Vet Sci ; 72: 56-63, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30929784

RESUMO

Greenhouses gas emission mitigation is a very important aspect of earth sustainability with greenhouse gasses reduction, a focus of agricultural and petrochemical industries. Methane is produced in nonruminant herbivores such as horses because they undergo hindgut fermentation. Although equine produce less methane than ruminant, increasing population of horses might increase their contribution to the present 1.2 to 1.7 Tg, estimate. Diet, feeding frequency, season, genome, and protozoa population influence methane production equine. In population, Methanomicrobiales, Methanosarcinales, Methanobacteriales, and Methanoplasmatales are the clade identified in equine. Methanocorpusculum labreanum is common among hindgut fermenters like horses and termite. Naturally, acetogenesis and interrelationship between the host and the immune-anatomical interaction are responsible for the reduced methane output in horses. However, to reduce methane output in equine, and increase energy derived from feed intake, the use of biochar, increase in acetogens, inclusion of fibre enzymes and plant extract, and recycling of fecal energy through anaerobic gas fermentation. These might be feasible ways to reducing methane contribution from horse and could be applied to ruminants too.


Assuntos
Euryarchaeota , Metano , Animais , Cavalos , Methanomicrobiales , Methanosarcinales , Ruminantes
8.
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
9.
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
10.
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
11.
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
Ciprofloxacina/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
12.
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
13.
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
14.
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
15.
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
16.
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 , Poluentes Químicos da Água
17.
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
18.
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
19.
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
20.
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
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