A Gram-positive, alkaliphilic bacterium, designated strain Zby6(T), was isolated from Zhabuye Lake in Tibet, China. The strain was able to grow at pH 8.0-11.0 (optimum at pH 10.0), in 0-8 % (w/v) NaCl (optimum at 3 %, w/v) and at 10-45 A degrees C (optimum at 37 A degrees C). Cells of the isolate were facultatively anaerobic and spore-forming rods with polar flagellum. The predominant isoprenoid quinone was MK-7, and its cell wall peptidoglycan contained meso-diaminopimelic acid. The major cellular fatty acids were iso-C-15:0, C-16:0 and anteiso-C-15:0. The major polar lipids consisted of phosphatidylglycerol, diphosphatidylglycerol, and phosphatidylethanolamine. The genomic DNA G+C content of the isolate was 38.9 mol%. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain Zby6(T) was a member of the genus Bacillus and most closely related to Bacillus cellulosilyticus DSM 2522(T) (97.7 % similarity). The DNA-DNA relatedness value between strain Zby6(T) and B. cellulosilyticus DSM 2522(T) was 59.2 +/- A 1.8 %. Comparative analysis of genotypic and phenotypic features indicated that strain Zby6(T) represents a novel species of the genus Bacillus, for which the name Bacillus alkalicola sp. nov. is proposed; the type strain is Zby6(T) (=CGMCC 1.10368(T) = JCM 17098(T) = NBRC 107743(T)).