A novel Gram-stain-positive, motile, catalase- and oxidase-positive, endospore-forming, aerobic, rod-shaped bacterium, designated strain JSM 099021(T), was isolated from an oyster collected from Naozhou Island in the South China Sea. Growth occurred with 0-15% (w/v) NaCl (optimum 2-4%) and at pH 6.0-10.0 (optimum pH 7.5) and at 10-45°C (optimum 30-35°C). meso-Diaminopimelic acid was present in the cell-wall peptidoglycan. The predominant respiratory quinone was menaquinone 7 (MK-7) and the major polar lipids consisted of diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol. The major cellular fatty acids were anteiso-C15:0, anteiso-C17:0, iso-C15:0 and iso-C16:0. The genomic DNA G + C content was 39.5 mol%. A phylogenetic analysis based on 16S rRNA gene sequences indicated that strain JSM 099021(T) belongs to the genus Bacillus, and was most closely related to the type strains of Bacillus halmapalus (sequence similarity 99.0%), Bacillus horikoshii (98.4%) and Bacillus cohnii (98.0%). The combination of phylogenetic analysis, DNA-DNA hybridization, phenotypic characteristics and chemotaxonomic data supported the proposal that strain JSM 099021(T) represents a new species of the genus Bacillus, for which the name Bacillus zhanjiangensis sp. nov. is proposed. The type strain was JSM 099021(T) (=DSM 23010(T) = KCTC 13713(T)).