scholarly journals Identification of Methanoculleus spp. as Active Methanogens during Anoxic Incubations of Swine Manure Storage Tank Samples

2012 ◽  
Vol 79 (2) ◽  
pp. 424-433 ◽  
Author(s):  
Maialen Barret ◽  
Nathalie Gagnon ◽  
Martin L. Kalmokoff ◽  
Edward Topp ◽  
Yris Verastegui ◽  
...  

ABSTRACTMethane emissions represent a major environmental concern associated with manure management in the livestock industry. A more thorough understanding of how microbial communities function in manure storage tanks is a prerequisite for mitigating methane emissions. Identifying the microorganisms that are metabolically active is an important first step. Methanogenic archaea are major contributors to methanogenesis in stored swine manure, and we investigated active methanogenic populations by DNA stable isotope probing (DNA-SIP). Following a preincubation of manure samples under anoxic conditions to induce substrate starvation, [U-13C]acetate was added as a labeled substrate. Fingerprint analysis of density-fractionated DNA, using length-heterogeneity analysis of PCR-amplifiedmcrAgenes (encoding the alpha subunit of methyl coenzyme M reductase), showed that the incorporation of13C into DNA was detectable atin situacetate concentrations (∼7 g/liter). Fingerprints of DNA retrieved from heavy fractions of the13C treatment were primarily enriched in a 483-bp amplicon and, to a lesser extent, in a 481-bp amplicon. Analyses based on clone libraries of themcrAand 16S rRNA genes revealed that both of these heavy DNA amplicons corresponded toMethanoculleusspp. Our results demonstrate that uncultivated methanogenic archaea related toMethanoculleusspp. were major contributors to acetate-C assimilation during the anoxic incubation of swine manure storage tank samples. Carbon assimilation and dissimilation rate estimations suggested thatMethanoculleusspp. were also major contributors to methane emissions and that the hydrogenotrophic pathway predominated during methanogenesis.

2013 ◽  
Vol 80 (5) ◽  
pp. 1684-1691 ◽  
Author(s):  
Baozhan Wang ◽  
Yan Zheng ◽  
Rong Huang ◽  
Xue Zhou ◽  
Dongmei Wang ◽  
...  

ABSTRACTAll cultivated ammonia-oxidizing archaea (AOA) within theNitrososphaeracluster (former soil group 1.1b) are neutrophilic. Molecular surveys also indicate the existence ofNitrososphaera-like phylotypes in acidic soil, but their ecological roles are poorly understood. In this study, we present molecular evidence for the chemolithoautotrophic growth ofNitrososphaera-like AOA in an acidic soil with pH 4.92 using DNA-based stable isotope probing (SIP). Soil microcosm incubations demonstrated that nitrification was stimulated by urea fertilization and accompanied by a significant increase in the abundance of AOA rather than ammonia-oxidizing bacteria (AOB). Real-time PCR analysis ofamoAgenes as a function of the buoyant density of the DNA gradient following the ultracentrifugation of the total DNA extracted from SIP microcosms indicated a substantial growth of soil AOA during nitrification. Pyrosequencing of the total 16S rRNA genes in the “heavy” DNA fractions suggested that archaeal communities were labeled to a much greater extent than soil AOB. Acetylene inhibition further showed that13CO2assimilation by nitrifying communities depended solely on ammonia oxidation activity, suggesting a chemolithoautotrophic lifestyle. Phylogenetic analysis of both13C-labeledamoAand 16S rRNA genes revealed that most of the active AOA were phylogenetically closely related to the neutrophilic strainsNitrososphaera viennensisEN76 and JG1 within theNitrososphaeracluster. Our results provide strong evidence for the adaptive growth ofNitrososphaera-like AOA in acidic soil, suggesting a greater metabolic versatility of soil AOA than previously appreciated.


2016 ◽  
Vol 82 (8) ◽  
pp. 2363-2371 ◽  
Author(s):  
Kaitlin C. Esson ◽  
Xueju Lin ◽  
Deepak Kumaresan ◽  
Jeffrey P. Chanton ◽  
J. Colin Murrell ◽  
...  

ABSTRACTThe objective of this study was to characterize metabolically active, aerobic methanotrophs in an ombrotrophic peatland in the Marcell Experimental Forest, in Minnesota. Methanotrophs were investigated in the field and in laboratory incubations using DNA-stable isotope probing (SIP), expression studies on particulate methane monooxygenase (pmoA) genes, and amplicon sequencing of 16S rRNA genes. Potential rates of oxidation ranged from 14 to 17 μmol of CH4g dry weight soil−1day−1. Within DNA-SIP incubations, the relative abundance of methanotrophs increased from 4%in situto 25 to 36% after 8 to 14 days. Phylogenetic analysis of the13C-enriched DNA fractions revealed that the active methanotrophs were dominated by the generaMethylocystis(type II;Alphaproteobacteria),Methylomonas, andMethylovulum(both, type I;Gammaproteobacteria). In field samples, a transcript-to-gene ratio of 1 to 2 was observed forpmoAin surface peat layers, which attenuated rapidly with depth, indicating that the highest methane consumption was associated with a depth of 0 to 10 cm. Metagenomes and sequencing of cDNApmoAamplicons from field samples confirmed that the dominant active methanotrophs wereMethylocystisandMethylomonas. Although type II methanotrophs have long been shown to mediate methane consumption in peatlands, our results indicate that members of the generaMethylomonasandMethylovulum(type I) can significantly contribute to aerobic methane oxidation in these ecosystems.


2015 ◽  
Vol 81 (14) ◽  
pp. 4607-4615 ◽  
Author(s):  
Xiaoqing Wang ◽  
Christine E. Sharp ◽  
Gareth M. Jones ◽  
Stephen E. Grasby ◽  
Allyson L. Brady ◽  
...  

ABSTRACTThe exopolysaccharides (EPSs) produced by some bacteria are potential growth substrates for other bacteria in soil. We used stable-isotope probing (SIP) to identify aerobic soil bacteria that assimilated the cellulose produced byGluconacetobacter xylinusor the EPS produced byBeijerinckia indica. The latter is a heteropolysaccharide comprised primarily ofl-guluronic acid,d-glucose, andd-glycero-d-mannoheptose.13C-labeled EPS and13C-labeled cellulose were purified from bacterial cultures grown on [13C]glucose. Two soils were incubated with these substrates, and bacteria actively assimilating them were identified via pyrosequencing of 16S rRNA genes recovered from13C-labeled DNA. Cellulose C was assimilated primarily by soil bacteria closely related (93 to 100% 16S rRNA gene sequence identities) to known cellulose-degrading bacteria. However,B. indicaEPS was assimilated primarily by bacteria with low identities (80 to 95%) to known species, particularly by different members of the phylumPlanctomycetes. In one incubation, members of thePlanctomycetesmade up >60% of all reads in the labeled DNA and were only distantly related (<85% identity) to any described species. Although it is impossible with SIP to completely distinguish primary polysaccharide hydrolyzers from bacteria growing on produced oligo- or monosaccharides, the predominance ofPlanctomycetessuggested that they were primary degraders of EPS. Other bacteria assimilatingB. indicaEPS included members of theVerrucomicrobia, candidate division OD1, and theArmatimonadetes. The results indicate that some uncultured bacteria in soils may be adapted to using complex heteropolysaccharides for growth and suggest that the use of these substrates may provide a means for culturing new species.


2012 ◽  
Vol 78 (23) ◽  
pp. 8245-8253 ◽  
Author(s):  
Kristina Paul ◽  
James O. Nonoh ◽  
Lena Mikulski ◽  
Andreas Brune

ABSTRACTTheEuryarchaeotacomprise both methanogenic and nonmethanogenic orders and many lineages of uncultivated archaea with unknown properties. One of these deep-branching lineages, distantly related to theThermoplasmatales, has been discovered in various environments, including marine habitats, soil, and also the intestinal tracts of termites and mammals. By comparative phylogenetic analysis, we connected this lineage of 16S rRNA genes to a large clade of unknownmcrAgene sequences, a functional marker for methanogenesis, obtained from the same habitats. The identical topologies of 16S rRNA andmcrAgene trees and the perfect congruence of all branches, including several novel groups that we obtained from the guts of termites and cockroaches, strongly suggested that they stem from the same microorganisms. This was further corroborated by two highly enriched cultures of closely related methanogens from the guts of a higher termite (Cubitermes ugandensis) and a millipede (Anadenobolussp.), which represented one of the arthropod-specific clusters in the respective trees. Numerous other pairs of habitat-specific sequence clusters were obtained from the guts of other termites and cockroaches but were also found in previously published data sets from the intestinal tracts of mammals (e.g., rumen cluster C) and other environments. Together with the recently describedMethanomassiliicoccus luminyensisisolated from human feces, which falls into rice cluster III, the results of our study strongly support the idea that the entire clade of “unculturedThermoplasmatales” in fact represents the seventh order of methanogenic archaea, for which the provisional name “Methanoplasmatales” is proposed.


2014 ◽  
Vol 81 (2) ◽  
pp. 604-613 ◽  
Author(s):  
David Wilkins ◽  
Xiao-Ying Lu ◽  
Zhiyong Shen ◽  
Jiapeng Chen ◽  
Patrick K. H. Lee

ABSTRACTMethanogenic archaea play a key role in biogas-producing anaerobic digestion and yet remain poorly taxonomically characterized. This is in part due to the limitations of low-throughput Sanger sequencing of a single (16S rRNA) gene, which in the past may have undersampled methanogen diversity. In this study, archaeal communities from three sludge digesters in Hong Kong and one wastewater digester in China were examined using high-throughput pyrosequencing of the methyl coenzyme M reductase (mcrA) and 16S rRNA genes.Methanobacteriales,Methanomicrobiales, andMethanosarcinaleswere detected in each digester, indicating that both hydrogenotrophic and acetoclastic methanogenesis was occurring. Two sludge digesters had similar community structures, likely due to their similar design and feedstock. Taxonomic classification of themcrAgenes suggested that these digesters were dominated by acetoclastic methanogens, particularlyMethanosarcinales, while the other digesters were dominated by hydrogenotrophicMethanomicrobiales. The proposed euryarchaeotal orderMethanomassiliicoccalesand the uncultured WSA2 group were detected with the 16S rRNA gene, and potentialmcrAgenes for these groups were identified. 16S rRNA gene sequencing also recovered several crenarchaeotal groups potentially involved in the initial anaerobic digestion processes. Overall, the two genes produced different taxonomic profiles for the digesters, while greater methanogen richness was detected using themcrAgene, supporting the use of this functional gene as a complement to the 16S rRNA gene to better assess methanogen diversity. A significant positive correlation was detected between methane production and the abundance ofmcrAtranscripts in digesters treating sludge and wastewater samples, supporting themcrAgene as a biomarker for methane yield.


2014 ◽  
Vol 64 (Pt_10) ◽  
pp. 3538-3545 ◽  
Author(s):  
Crystal N. Johnson ◽  
Terence R. Whitehead ◽  
Michael A. Cotta ◽  
Robert E. Rhoades ◽  
Paul A. Lawson

A species of a previously unknown Gram-positive-staining, anaerobic, coccus-shaped bacterium recovered from a swine manure storage tank was characterized using phenotypic, chemotaxonomic, and molecular taxonomic methods. Comparative 16S rRNA gene sequencing studies and biochemical characteristics demonstrated that this organism is genotypically and phenotypically distinct, and represents a previously unknown sub-line within the order Clostridiales , within the phylum Firmicutes . Pairwise sequence analysis demonstrated that the novel organism clustered within the genus Peptoniphilus , most closely related to Peptoniphilus methioninivorax sharing a 16S rRNA gene sequence similarity of 95.5 %. The major long-chain fatty acids were found to be C14 : 0 (22.4 %), C16 : 0 (15.6 %), C16 : 1ω7c (11.3 %) and C16 : 0 ALDE (10.1 %) and the DNA G +C content was 31.8 mol%. Based upon the phenotypic and phylogenetic findings presented, a novel species Peptoniphilus stercorisuis sp. nov. is proposed. The type strain is SF-S1T ( = DSM 27563T = NBRC 109839T). In addition, it is proposed to accommodate the genera Peptoniphilus , Anaerococcus , Anaerosphaera , Finegoldia , Gallicola , Helcococcus , Murdochiella and Parvimonas in a new family of the order Clostridiales , for which the name Peptoniphilaceae fam. nov. is proposed; the type genus of the family is Peptoniphilus .


2020 ◽  
Vol 86 (23) ◽  
Author(s):  
Wei-Wei Xia ◽  
Jun Zhao ◽  
Yan Zheng ◽  
Hui-Min Zhang ◽  
Jia-Bao Zhang ◽  
...  

ABSTRACT Long-term nitrogen field fertilization often results in significant changes in nitrifying communities that catalyze a key step in the global N cycle. However, whether microcosm studies are able to inform the dynamic changes in communities of ammonia-oxidizing bacteria (AOB) and archaea (AOA) under field conditions remains poorly understood. This study aimed to evaluate the transcriptional activities of nitrifying communities under in situ conditions, and we found that they were largely similar to those of 13C-labeled nitrifying communities in the urea-amended microcosms of soils that had received different N fertilization regimens for 22 years. High-throughput sequencing of 16S rRNA genes and transcripts suggested that Nitrosospira cluster 3-like AOB and Nitrososphaera viennensis-like AOA were significantly stimulated in N-fertilized fresh soils. Real-time quantitative PCR demonstrated that the significant increase of AOA and AOB in fresh soils upon nitrogen fertilization could be preserved in the air-dried soils. DNA-based stable-isotope probing (SIP) further revealed the greatest labeling of Nitrosospira cluster 3-like AOB and Nitrosospira viennensis-like AOA, despite the strong advantage of AOB over AOA in the N-fertilized soils. Nitrobacter-like nitrite-oxidizing bacteria (NOB) played more important roles than Nitrospira-like NOB in urea-amended SIP microcosms, while the situation was the opposite under field conditions. Our results suggest that long-term fertilization selected for physiologically versatile AOB and AOA that could have been adapted to a wide range of substrate ammonium concentrations. It also provides compelling evidence that the dominant communities of transcriptionally active nitrifiers under field conditions were largely similar to those revealed in 13C-labeled microcosms. IMPORTANCE The role of manipulated microcosms in microbial ecology has been much debated, because they cannot entirely represent the in situ situation. We collected soil samples from 20 field plots, including 5 different treatments with and without nitrogen fertilizers for 22 years, in order to assess active nitrifying communities by in situ transcriptomics and microcosm-based stable-isotope probing. The results showed that chronic N enrichment led to competitive advantages of Nitrosospira cluster 3-like AOB over N. viennensis-like AOA in soils under field conditions. Microcosm labeling revealed similar results for active AOA and AOB, although an apparent discrepancy was observed for nitrite-oxidizing bacteria. This study suggests that the soil microbiome represents a relatively stable community resulting from complex evolutionary processes over a large time scale, and microcosms can serve as powerful tools to test the theory of environmental filtering on the key functional microbial guilds.


2014 ◽  
Vol 80 (7) ◽  
pp. 2240-2247 ◽  
Author(s):  
Gerald W. Tannock ◽  
Blair Lawley ◽  
Karen Munro ◽  
Ian M. Sims ◽  
Julian Lee ◽  
...  

ABSTRACTKnowledge of the trophisms that underpin bowel microbiota composition is required in order to understand its complex phylogeny and function. Stable-isotope (13C)-labeled inulin was added to the diet of rats on a single occasion in order to detect utilization of inulin-derived substrates by particular members of the cecal microbiota. Cecal digesta from Fibruline-inulin-fed rats was collected prior to (0 h) and at 6, 12, 18 and 24 h following provision of the [13C]inulin diet. RNA was extracted from these cecal specimens and fractionated in isopycnic buoyant density gradients in order to detect13C-labeled nucleic acid originating in bacterial cells that had metabolized the labeled dietary constituent. RNA extracted from specimens collected after provision of the labeled diet was more dense than 0-h RNA. Sequencing of 16S rRNA genes amplified from cDNA obtained from these fractions showed thatBacteroides uniformis,Blautia glucerasea,Clostridium indolis, andBifidobacterium animaliswere the main users of the13C-labeled substrate. Culture-based studies of strains of these bacterial species enabled trophisms associated with inulin and its hydrolysis products to be identified.B. uniformisutilized Fibruline-inulin for growth, whereas the other species used fructo-oligosaccharide and monosaccharides. Thus, RNA–stable-isotope probing (RNA-SIP) provided new information about the use of carbon from inulin in microbiota metabolism.


2021 ◽  
Author(s):  
Ömer K. Coskun ◽  
Aurèle Vuillemin ◽  
Florence Schubotz ◽  
Frieder Klein ◽  
Susanna E. Sichel ◽  
...  

AbstractThermodynamic models predict that H2 is energetically favorable for seafloor microbial life, but how H2 affects anabolic processes in seafloor-associated communities is poorly understood. Here, we used quantitative 13C DNA stable isotope probing (qSIP) to quantify the effect of H2 on carbon assimilation by microbial taxa synthesizing 13C-labeled DNA that are associated with partially serpentinized peridotite rocks from the equatorial Mid-Atlantic Ridge. The rock-hosted seafloor community was an order of magnitude more diverse compared to the seawater community directly above the rocks. With added H2, peridotite-associated taxa increased assimilation of 13C-bicarbonate and 13C-acetate into 16S rRNA genes of operational taxonomic units by 146% (±29%) and 55% (±34%), respectively, which correlated with enrichment of H2-oxidizing NiFe-hydrogenases encoded in peridotite-associated metagenomes. The effect of H2 on anabolism was phylogenetically organized, with taxa affiliated with Atribacteria, Nitrospira, and Thaumarchaeota exhibiting the most significant increases in 13C-substrate assimilation in the presence of H2. In SIP incubations with added H2, an order of magnitude higher number of peridotite rock-associated taxa assimilated 13C-bicarbonate, 13C-acetate, and 13C-formate compared to taxa that were not associated with peridotites. Collectively, these findings indicate that the unique geochemical nature of the peridotite-hosted ecosystem has selected for H2-metabolizing, rock-associated taxa that can increase anabolism under high H2 concentrations. Because ultramafic rocks are widespread in slow-, and ultraslow-spreading oceanic lithosphere, continental margins, and subduction zones where H2 is formed in copious amounts, the link between H2 and carbon assimilation demonstrated here may be widespread within these geological settings.


2011 ◽  
Vol 77 (11) ◽  
pp. 3773-3785 ◽  
Author(s):  
Sindy Hunger ◽  
Oliver Schmidt ◽  
Maik Hilgarth ◽  
Marcus A. Horn ◽  
Steffen Kolb ◽  
...  

ABSTRACTMethanogenesis in wetlands is dependent on intermediary substrates derived from the degradation of biopolymers. Formate is one such substrate and is stimulatory to methanogenesis and acetogenesis in anoxic microcosms of soil from the fen Schlöppnerbrunnen. Formate dissimilation also yields CO2as a potential secondary substrate. The objective of this study was to resolve potential differences between anaerobic formate- and CO2-utilizing prokaryotes of this fen by stable isotope probing. Anoxic soil microcosms were pulsed daily with low concentrations of [13C]formate or13CO2(i.e., [13C]bicarbonate). Taxa were evaluated by assessment of 16S rRNA genes,mcrA(encoding the alpha-subunit of methyl-coenzyme M reductase), andfhs(encoding formyltetrahydrofolate synthetase). Methanogens, acetogens, and formate-hydrogen lyase-containing taxa appeared to compete for formate. Genes affiliated withMethanocellaceae,Methanobacteriaceae,Acetobacteraceae, andRhodospirillaceaewere13C enriched (i.e., labeled) in [13C]formate treatments, whereas genes affiliated withMethanosarcinaceae,Conexibacteraceae, andSolirubrobacteraceaewere labeled in13CO2treatments. [13C]acetate was enriched in [13C]formate treatments, but labeling of known acetogenic taxa was not detected. However, several phylotypes were affiliated with acetogen-containing taxa (e.g.,Sporomusa).Methanosaetaceae-affiliated methanogens appeared to participate in the consumption of acetate. Twelve and 58 family-level archaeal and bacterial 16S rRNA phylotypes, respectively, were detected, approximately half of which had no isolated representatives.Crenarchaeotaconstituted half of the detected archaeal 16S rRNA phylotypes. The results highlight the unresolved microbial diversity of the fen Schlöppnerbrunnen, suggest that differing taxa competed for the same substrate, and indicate thatMethanocellaceae,Methanobacteriaceae,Methanosarcinaceae, andMethanosaetaceaewere linked to the production of methane, but they do not clearly resolve the taxa responsible for the apparent conversion of formate to acetate.


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