文摘
A novel mesophilic, methylotrophic, methanogenic archaeon, designated strain EK1T, was enriched and isolated from wetland sediment. Phylogenetic analysis showed that strain EK1T was affiliated with the genus Methanomethylovorans within the family Methanosarcinaceae, and shared the highest 16S rRNA and methyl-coenzyme M reductase alpha-subunit gene sequence similarity with the type strain of Methanomethylovorans hollandica (98.8 and 92.6%, respectively). The cells of strain EK1T were observed to be Gram-negative, non-motile and irregular cocci that did not lyse in 0.1% (w/v) sodium dodecyl sulfate. Methanol, mono-, di- and trimethylamine, dimethyl sulfide and methanethiol were found to be used as catabolic and methanogenic substrates, whereas H2/CO2, formate, 2-propanol and acetate were not. Growth was observed at 250 (optimum, 37), at pH 5.5.5 (optimum, pH 6.0.5) and in the presence of 0.1M NaCl (optimum, 0M). Growth and methane production rates were stimulated in the presence of H2/CO2 although methane production and growth yields were not significantly affected; acetate, formate, 2-propanol and CO/CO2/N2 did not affect methane production. CoCl2 (0.6.0) and FeCl2 (25mg/l) stimulated growth, while yeast extract and peptone did not. The DNANA hybridization experiment revealed a relatedness of <20% between EK1T and the type strains of the genus Methanomethylovorans. The DNA G+C content of strain EK1T was determined to be 39.2mol%. Based on the polyphasic taxonomic study, strain EK1T represents a novel species belonging to the genus Methanomethylovorans, for which the name Methanomethylovorans uponensis sp. nov. is proposed. The type strain is strain EK1T(=NBRC 109636T=KCTC 4119T=JCM 19217T).