%0 Journal Article %A Yashiro, Yuto %A Sakai, Sanae %A Ehara, Masayuki %A Miyazaki, Masayuki %A Yamaguchi, Takashi %A Imachi, Hiroyuki %T Methanoregula formicica sp. nov., a methane-producing archaeon isolated from methanogenic sludge %D 2011 %J International Journal of Systematic and Evolutionary Microbiology, %V 61 %N 1 %P 53-59 %@ 1466-5034 %R https://doi.org/10.1099/ijs.0.014811-0 %K UASB, upflow anaerobic sludge blanket %K FISH, fluorescence in situ hybridization %I Microbiology Society, %X A novel methane-producing archaeon, strain SMSPT, was isolated from an anaerobic, propionate-degrading enrichment culture that was originally obtained from granular sludge in a mesophilic upflow anaerobic sludge blanket (UASB) reactor used to treat a beer brewery effluent. Cells were non-motile, blunt-ended, straight rods, 1.0–2.6 μm long by 0.5 μm wide; cells were sometimes up to 7 μm long. Asymmetrical cell division was observed in rod-shaped cells. Coccoid cells (0.5–1.0 μm in diameter) were also observed in mid- to late-exponential phase cultures. Growth was observed between 10 and 40 °C (optimum, 30–33 °C) and pH 7.0 and 7.6 (optimum, pH 7.4). The G+C content of the genomic DNA was 56.2 mol%. The strain utilized formate and hydrogen for growth and methane production. Based on comparative sequence analyses of the 16S rRNA and mcrA (encoding the alpha subunit of methyl-coenzyme M reductase, a key enzyme in the methane-producing pathway) genes, strain SMSPT was affiliated with group E1/E2 within the order Methanomicrobiales. The closest relative based on both 16S rRNA and mcrA gene sequences was Methanoregula boonei 6A8T (96.3 % 16S rRNA gene sequence similarity, 85.4 % deduced McrA amino acid sequence similarity). The percentage of 16S rRNA gene sequence similarity indicates that strain SMSPT and Methanoregula boonei 6A8T represent different species within the same genus. This is supported by our findings of shared phenotypic properties, including cell morphology and growth temperature range, and phenotypic differences in substrate usage and pH range. Based on these genetic and phenotypic properties, we propose that strain SMSPT represents a novel species of the genus Methanoregula, for which we propose the name Methanoregula formicica sp. nov., with the type strain SMSPT (=NBRC 105244T =DSM 22288T). %U https://www.microbiologyresearch.org/content/journal/ijsem/10.1099/ijs.0.014811-0