<i>Gracilibacteraceae fam. nov</i>

Lee, Yong‐Jin; Onyenwoke, Rob U.; Wiegel, Juergen

doi:10.1002/9781118960608.fbm00131

Cited by 1 publication

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“…In terms of overall community composition ( Figure 6 B), modules 232, 234, 245, and 246 showed close taxonomic patterns dominated by Firmicutes and Bacteroidetes , taxa similar to those found in animal GITs from which most of the known Methanomassiliicoccales have been enriched or isolated so far [ 20 , 21 , 22 , 26 ]. These modules were predominantly composed of Bacteroidales ( Dysgonomonadaceae and Rikenellaceae ) and various Clostridiales ( Christensenellaceae R-7 group, Gracilibacteraceae , Hungateiclostridiaceae , Oscillospiraceae , Ruminococcaceae ) mainly reported to be able to produce acetate and/or H 2 as fermentative end products and sometimes to form partnerships with hydrogen-consuming methanogens (i.e., Methanospirillum hungatei , Methanobrevibacter smithii ) ( Table S5 ) [ 82 , 126 , 127 , 128 , 129 , 130 , 131 , 132 ]. Such bacteria pattern could possibly be explained by the utilization of a medium rich in organic compounds which could be used as substrates for fermentation or acetogenesis.…”

Section: Resultsmentioning

confidence: 99%

New Insights into the Ecology and Physiology of Methanomassiliicoccales from Terrestrial and Aquatic Environments

et al. 2020

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Members of the archaeal order Methanomassiliicoccales are methanogens mainly associated with animal digestive tracts. However, environmental members remain poorly characterized as no representatives not associated with a host have been cultivated so far. In this study, metabarcoding screening combined with quantitative PCR analyses on a collection of diverse non-host-associated environmental samples revealed that Methanomassiliicoccales were very scarce in most terrestrial and aquatic ecosystems. Relative abundance of Methanomassiliicoccales and substrates/products of methanogenesis were monitored during incubation of environmental slurries. A sediment slurry enriched in Methanomassiliicoccales was obtained from a freshwater sample. It allowed the reconstruction of a high-quality metagenome-assembled genome (MAG) corresponding to a new candidate species, for which we propose the name of Candidatus ‘Methanomassiliicoccus armoricus MXMAG1’. Comparison of the annotated genome of MXMAG1 with the published genomes and MAGs from Methanomassiliicoccales belonging to the 2 known clades (‘free-living’/non-host-associated environmental clade and ‘host-associated’/digestive clade) allowed us to explore the putative physiological traits of Candidatus ‘M. armoricus MXMAG1’. As expected, Ca. ‘Methanomassiliicoccus armoricus MXMAG1’ had the genetic potential to produce methane by reduction of methyl compounds and dihydrogen oxidation. This MAG encodes for several putative physiological and stress response adaptations, including biosynthesis of trehalose (osmotic and temperature regulations), agmatine production (pH regulation), and arsenic detoxication, by reduction and excretion of arsenite, a mechanism that was only present in the ‘free-living’ clade. An analysis of co-occurrence networks carried out on environmental samples and slurries also showed that Methanomassiliicoccales detected in terrestrial and aquatic ecosystems were strongly associated with acetate and dihydrogen producing bacteria commonly found in digestive habitats and which have been reported to form syntrophic relationships with methanogens.

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