Stewart Lucy C, Jung Jong-Hyun, Kim You-Tae, Kwon Soon-Wo, Park Cheon-Seok, Holden James F
Department of Microbiology, University of Massachusetts, Amherst, MA 01003, USA.
Research Division for Biotechnology, Korea Atomic Energy Research Institute, Jeongeup 580-185, Republic of Korea.
Int J Syst Evol Microbiol. 2015 Apr;65(Pt 4):1280-1283. doi: 10.1099/ijs.0.000097. Epub 2015 Jan 29.
A hyperthermophilic methanogen, strain JH146(T), was isolated from 26 °C hydrothermal vent fluid emanating from a crack in basaltic rock at Marker 113 vent, Axial Seamount in the northeastern Pacific Ocean. It was identified as an obligate anaerobe that uses only H2 and CO2 for growth. Phylogenetic analysis based on 16S rRNA gene sequences showed that the strain is more than 97% similar to other species of the genus Methanocaldococcus . Therefore, overall genome relatedness index analyses were performed to establish that strain JH146(T) represents a novel species. For each analysis, strain JH146(T) was most similar to Methanocaldococcus sp. FS406-22, which can fix N2 and also comes from Marker 113 vent. However, strain JH146(T) differs from strain FS406-22 in that it cannot fix N2. The average nucleotide identity score for strain JH146(T) was 87%, the genome-to-genome direct comparison score was 33-55% and the species identification score was 93%. For each analysis, strain JH146(T) was below the species delineation cut-off. Full-genome gene synteny analysis showed that strain JH146(T) and strain FS406-22 have 97% genome synteny, but strain JH146(T) was missing the operons necessary for N2 fixation and assimilatory nitrate reduction that are present in strain FS406-22. Based on its whole genome sequence, strain JH146(T) is suggested to represent a novel species of the genus Methanocaldococcus for which the name Methanocaldococcus bathoardescens is proposed. The type strain is JH146(T) ( = DSM 27223(T) = KACC 18232(T)).
从东北太平洋轴海山113号标记处玄武岩裂缝中涌出的26℃热液喷口流体中分离出一株嗜热产甲烷菌，菌株JH146(T)。它被鉴定为专性厌氧菌，仅利用氢气和二氧化碳生长。基于16S rRNA基因序列的系统发育分析表明，该菌株与甲烷热球菌属的其他物种相似度超过97%。因此，进行了全基因组相关性指数分析，以确定菌株JH146(T)代表一个新物种。在每次分析中，菌株JH146(T)与能固定氮气且也来自113号标记处喷口的甲烷热球菌属菌株FS406-22最为相似。然而，菌株JH146(T)与菌株FS406-22的不同之处在于它不能固定氮气。菌株JH146(T)的平均核苷酸同一性得分是87%，基因组到基因组直接比较得分是33 - 55%，物种鉴定得分是93%。在每次分析中，菌株JH146(T)都低于物种划分界限。全基因组基因共线性分析表明，菌株JH146(T)和菌株FS406-22有97%的基因组共线性，但菌株JH146(T)缺少菌株FS406-22中存在的固氮和同化硝酸盐还原所需的操纵子。基于其全基因组序列，建议菌株JH146(T)代表甲烷热球菌属的一个新物种，为此提出了“Methanocaldococcus bathoardescens”这个名称。模式菌株是JH146(T)（=DSM 27223(T)=KACC 18232(T)）。
