Elioraea thermophila sp. nov., a thermophilic bacterium from hot spring of the class Alphaproteobacteria, emended description of the genus Elioraea and proposal of Elioraeaceae fam. nov.

Abstract

A Gram-staining-negative, aerobic, curved rod-shaped and thermophilic bacterial strain, designated YIM 72297T, was isolated from a sediment sample collected from a hot spring in Tengchong county, Yunnan province, south-west China. Growth was observed at pH 5.0-9.0 with an optimum of pH 7.0-7.5, and at 45-60 °C with an optimum of 55 °C. Positive for catalase and oxidase. The 16S rRNA gene sequence comparison indicated that strain YIM 72297T was most closely related to Elioraea tepidiphila DSM 17972T (96.9 %) and showed <91 % sequence similarities to members of the order Rhodospirillales. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain YIM 72297T formed a distinct lineage within the genus Elioraea, and revealed that the genus Elioraea formed a novel family-level clade in the order Rhodospirillales. The ANI and the dDNA-DNA hybridization estimate values between strains YIM 72297T and Elioraea tepidiphila DSM 17972T were 70.8 and 20.1 %, respectively. Strain YIM 72297T contained Q-10 as the predominant ubiquinone. The major fatty acids (>5 %) were summed C18 : 0 (35.8 %), summed feature 8 (30.1 %), C16 : 0 (12.6 %), C18 : 1 2OH (5.6 %) and C16 : 0 2OH (5.4 %). The polar lipids consisted of phosphatidylcholine, phosphatidylethanolamine, diphosphosphatidylglycerol and phosphatidylglycerol in addition to two unidentified aminolipids. The DNA G+C content of YIM 72297T was 70.8 mol% (draft genome). On the basis of the polyphasic taxonomic evidence presented in this study, strain YIM 72297T should be classified as representing a novel species of the genus Elioraea, for which the name Elioraea thermophila sp. nov. is proposed, with the type strain YIM 72297T (=CCTCC AB 2017169T=KCTC 62323T). In addition, a novel family, Elioraeaceae fam. nov., is proposed to accommodate the genus Elioraea.