Methanococcoides orientis sp. nov., a methylotrophic methanogen isolated from sediment of the East China Sea

Abstract

A novel methylotrophic methanogen Methanococcoides orientis sp. nov. was isolated from East China Sea sediment. Type strain LMO-1T of Methanococcoides orientis sp. nov. was irregular 1–2 µm cocci without flagella. Strain LMO-1T could utilize a variety of methylated compounds including methanol, methylamine, dimethylamine and trimethylamine for growth and methanogenesis, while H2/CO2 or acetate could not be used for growth or methanogenesis. Optimum growth temperature was 30–35 °C, optimum pH range for growth was 7.0–7.5, while the optimum salinity spectrum for growth was 1.0%–5.0% NaCl. Based on 16S rRNA gene similarity, strain LMO-1T belongs to Methanococcoides, with the highest sequence similarity to Methanococcoides methy-lutens DSM 2657T (99.8 %), Methanococcoides vulcani SLH33T(99.4 %), followed by Methanococcoides alaskense AK-5T(98.1 %), Methanococcoides burtonii DSM 6242T (98.0 %). Digital DNA–DNA hybridization also showed highest similarity with Methanococ-coides methylutens DSM 2657T, with the value of 58.4 %. The average nucleotide identity between strain LMO-1T and Methano-coccoides methylutens DSM 2657T was 94.06 %. In summary, LMO-1T represents a novel species of the genus Methaococcoides, for which the name Methanococcoides orientis sp. nov. is proposed. The type strain is LMO-1T (=MCCC 4K00106T=JCM 39195T).