A low-G+C-content Gram-positive bacterium, designated CV53T, phylogenetically related to species of the genus Bacillus, was isolated from a highly alkaline non-saline groundwater environment (pH 11.4). This organism comprised rod-shaped cells, was aerobic, did not display spore formation, was catalase- and oxidase-negative, had an optimum growth temperature of 40 degrees C and had an optimum pH of approximately 7.0-8.5. Optimal growth was observed in the absence of NaCl, but growth did occur at NaCl concentrations up to 3.0%. The strain possessed an A1gamma-type peptidoglycan cell wall and the major respiratory quinone was MK-7. The predominant fatty acids were anteiso-C15:0, iso-C15:0 and anteiso-C17:0. The G+C content of the DNA was 43.1 mol%. Phylogenetic analyses of the 16S rRNA gene sequence revealed that the novel isolate is closely related to the type strain of Bacillus jeotgali, forming a coherent cluster supported by bootstrap analysis at a confidence level of 90%. The pairwise similarity of the 16S rRNA gene sequences of the two strains is 97.7%. On the basis of the phylogenetic analyses and the distinct phenotypic characteristics, strain CV53T represents a novel species within the genus Bacillus, for which we propose the name Bacillus foraminis sp. nov. The type strain is CV53T (=LMG 23174T=CIP 108889T).