Gracilibacillus kekensis sp. nov., a moderate halophile isolated from Keke Salt Lake

A novel moderately halophilic bacterium, designated strain K170(T), was isolated from Keke Salt Lake in Qinghai, China. The strain grew with 0-22 % (w/v) NaCl, at 4-50 °C and at pH 6-11, with optimum growth in 3 % (w/v) NaCl, at 40 °C and at pH 8. The predominant respiratory quinone was menaquinone 7 (MK-7). The polar lipids included diphosphatidylglycerol, phosphatidylglycerol, unidentified phospholipids, aminolipids and glycolipids. The major cellular fatty acids were anteiso-C(15 : 0), iso-C(15 : 0) and anteiso-C(17 : 0). The DNA G+C content was 35.8 mol%. Phylogenetic analysis based on the full-length 16S rRNA gene sequence revealed that strain K170(T) was a member of the genus Gracilibacillus. High levels of 16S rRNA gene sequence similarity were found between strain K170(T) and Gracilibacillus boraciitolerans DSM 17256(T) (97.3 %) and Gracilibacillus thailandensis JCM 15569(T) (97.1 %). 16S rRNA gene sequence similarities between strain K170(T) and the type strains of other recognized members of the genus Gracilibacillus were below 97 %. The DNA-DNA hybridization values of strain K170(T) with G. boraciitolerans DSM 17256(T) and G. thailandensis JCM 15569(T) were 21.9 % and 34.3 %, respectively. On the basis of these results, strain K170(T) is considered to represent a novel species of the genus Gracilibacillus, for which the name Gracilibacillus kekensis sp. nov. is proposed; the type strain is K170(T) ( = CGMCC 1.10681(T) = DSM 23178(T)).