Abstract
A novel methylotrophic methanogen Methanococcoides orientis sp. nov. was isolated from East China Sea sediment. Type strain LMO-1(T) of Methanococcoides orientis sp. nov. was irregular 1-2 mu m cocci without flagella. Strain LMO-1(T) could utilize a variety of methylated compounds including methanol, methylamine, dimethylamine and trimethylamine for growth and methanogenesis, while H 2/CO 2 or acetate could not be used for growth or methanogenesis. Optimum growth temperature was 30-35 degrees 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-1(T) belongs to Methanococcoides, with the highest sequence similarity to Methanococcoides methylutens DSM 2657(T) (99.8 %), Methanococcoides vulcani SLH33(T)(99.4 %), followed by Methanococcoides alaskense AK-5(T)(98.1%), Methanococcoides burtonii DSM 6242(T) (98.0%). Digital DNA-DNA hybridization also showed highest similarity with Methanococcoides methylutens DSM 2657(T), with the value of 58.4 %. The average nucleotide identity between strain LMO-1(T) and Methanococcoides methylutens DSM 2657(T) was 94.06%. In summary, LMO-1(T) represents a novel species of the genus Methaococcoides, for which the name Methanococcoides orientis sp. nov. is proposed. The type strain is LMO-1(T) (=MCCC 4K00106(T)=JCM 39195(T)).