Virgibacillus tibetensis sp. nov., isolated from salt lake on the Tibetan plateau of China.

Abstract

One bacterial strain, designated as C22-A2^T, was isolated from Lake LungmuCo in Tibet. Cells of strain C22-A2^T were long rod-shaped, Gram-stain-negative, non-spore-forming, with positive catalase and oxidase activity. Optimal growth occurred at 20-25 °C, pH 8.0 and with 3.0-7.0% (w/v) NaCl. Phylogenetic analysis of 16S rRNA gene and whole genome sequences revealed that strain C22-A2^T belonged to the genus Virgibacillus, showing the highest 16S rRNA gene similarity to Virgibacillus halodenitrificans DSM 10037^T (97.6%). The average nucleotide identity values between strain C22-A2^T and the type strains of related species in the genus Virgibacillus were less than 74.4% and the digital DNA-DNA hybridization values were less than 20.2%, both below the species delineation thresholds of 95 and 70% respectively. The genome analysis revealed that strain C22-A2^T harboured genes responsible for osmotic and oxidative stress, enabling it to adapt to its surrounding environment. In terms of biochemical and physiological characteristics, strain C22-A2^T shared similar characteristics with the genus Virgibacillus, including the predominant cellular fatty acid anteiso-C_15 : 0, the major respiratory quinone MK-7, as well as the polar lipids phosphatidylglycerol and diphosphatidylglycerol. Based on the comprehensive analysis of phylogenetic, phylogenomic, morphological, physiological and biochemical characteristics, strain C22-A2^T is proposed to represent a novel species of the genus Virgibacillus, named as Virgibacillus tibetensis sp. nov. (=CGMCC 1.19202^T=KCTC 43426^T).