Stenotrophobium rhamnosiphilum gen. nov., sp. nov., isolated from a glacier, proposal of Steroidobacteraceae fam. nov. in Nevskiales and emended description of the family Nevskiaceae.

A Gram-stain-negative strain, designated GT1R17T, was isolated from an ervoconite sample collected from Gawalong glacier in the Tibet Autonomous Region, PR China. Strain GT1R17T was catalase- and oxidase-positive, and grew optimally at 20-25°C and pH 7.0. The highest level of 16S rRNA gene sequence similarities were found to members of the genera Nevskia(92.27-93.15 %) and Hydrocarboniphaga(91.92-92.96 %). Phylogenetic analyses based on 16S rRNA gene sequences and genomic data revealed that the strain GT1R17T belonged to the family Nevskiaceae, but could not be assigned to any known genera. The genomic DNA G+C content was 54.4 mol%. The major fatty acids were summed feature 3 (C16 : 1ω6c and/or C16 : 1ω7c), summed feature 8 (C18 : 1 ω7c and/or C18 : 1ω6c), C16 : 0, iso-C16 : 0 and summed feature 2 (C14 : 0 3OH and/or iso-C16 : 1 I). The polar lipids were phosphatidylglycerol, phosphatidylethanolamine and one unidentified lipid. The ubiquinone was Q-8. On the basis of the phenotypic, chemotaxonomic, genotypic and phylogenetic data, a novel species of a new genus,Stenotrophobiumrhamnosiphilum gen. nov., sp. nov. within the family Nevskiaceae, is proposed, with GT1R17T (=CGMCC 1.16137T=NBRC 113346T) as the type strain. In addition, phylogenetic analyses revealed that Steroidobacter and Povalibacter formed an independent clade in the order Nevskiales and were away from the families Nevskiaceae, Algiphilaceae and Salinisphaeraceae. Therefore, we propose to remove Steroidobacter and Povalibacter from the family Nevskiaceae and propose a new family Steroidobacteraceae in the order Nevskiales.