At the subspecies level, the gyrB gene sequence could be used to discriminate B. subtilis subsp. subtilis from B. subtilis subsp. spizizenii (5 %sequence divergence). This result was consistent with that of gyrA gene sequence analysis (4.8 % sequence divergence). The 16S rRNA gene sequences of all Bacillus strains tested revealed more than 98 % similarity.These results indicate that the gyrB gene is more useful than the 16S rRNA gene for species and subspecies identification in the B. subtilis group.