Virgibacillus sediminis sp. nov., a moderately halophilic bacterium isolated from a salt lake in China

Abstract

A Gram-positive, moderately halophilic, alkalitolerant, strictly aerobic, oxidase- and catalase-positive, rod-shaped bacterium, strain YIM kkny3T, was isolated from a sediment sample collected from a salt lake in the Qaidam Basin of north-west China. Cells were motile by means of peritrichous flagella and formed ellipsoidal endospores lying in subterminal swollen sporangia. Growth occurred with 1-20% (w/v) total salts (optimum, 5-10%) and at pH 6.0-10.5 (optimum, pH 7.5-8.0) and 10-55 degrees C (optimum, 35-40 degrees C). It was unable to grow with NaCl as the only salt. meso-Diaminopimelic acid was present in the cell-wall peptidoglycan. The strain contained menaquinone 7 (MK-7) as the predominant respiratory quinone and diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and an unidentified phospholipid as polar lipids. The major cellular fatty acids were anteiso-C15:0 and anteiso-C17:0. The DNA G+C content was 40.9 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain YIM kkny3T belonged to the genus Virgibacillus, and was most closely related to the type strains of Virgibacillus olivae (97.1% similarity), Virgibacillus marismortui (97.0%) and Virgibacillus kekensis (96.8%). Levels of DNA-DNA relatedness between strain YIM kkny3T and the type strains of V. olivae, V. marismortui and V. kekensis were 12.4, 10.6 and 15.7%, respectively. The combination of phylogenetic analysis, genotypic data, phenotypic characteristics and chemotaxonomic differences indicated that strain YIM kkny3T represents a novel species of the genus Virgibacillus, for which the name Virgibacillus sediminis sp. nov. is proposed. The type strain is YIM kkny3T (=CCTCC AA 207023T=DSM 19797T=KCTC 13193T).