Roseomonas alkaliterrae sp. nov., isolated from an alkali geothermal soil sample in Tengchong, Yunnan, south-west China

Abstract

An alkalitolerant, thermotolerant and Gram-stain negative bacterium, designated strain YIM 78007(T), was isolated from an alkaline geothermal soil sample from Hehua hot spring, Tengchong, Yunnan province, south-west China. Cells of strain YIM 78007(T) were observed to be aerobic and short rod-shaped. The colonies were observed to be orange-red, convex and circular. 16S rRNA gene sequence-based phylogenetic analysis showed that strain YIM 78007(T) clustered with members of the genus Roseomonas (with similarities from 97.2 to 92.2%). Optimal growth of strain YIM 78007 occurs at 40-50°C and pH 8.0-10.0. The predominant ubiquinone was identified as Q-10 and the major fatty acids were identified as C18:1 ω7c and C16:0. The polar lipids were identified as diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, two unidentified aminolipids and one unknown phospholipid. The G+C content of the genomic DNA was determined to be 63mol%. The levels of DNA-DNA hybridization relatedness between strain YIM 78007(T) and its closet neighbours (Roseomonas lacus JCM 13283(T) and Roseomonas terrae JCM 14592(T)) were well below the threshold required for the proposal of a novel species. The results of physiological and biochemical characteristics, the phylogenetic analysis, as well as low DNA-DNA hybridization values, allowed the phenotypic and genotypic differentiation of strain YIM 78007(T) from its closest phylogenetic neighbours. Therefore, strain YIM 78007(T) is considered to represent a novel species of the genus Roseomonas, for which the name Roseomonas alkaliterrae sp. nov. is proposed. The type strain is YIM 78007(T) (=BCRC 80644(T)=JCM 19656(T)).