Phylogenetic analysis of Bacillus subtilis and related taxa based on partial gyrA gene sequences

Partial gyrA sequences were determined for twelve strains belonging to Baci llus amyloliquefaciens, B. atrophaeus, B. licheniformis, B. mojavensis,B. s ubtilis subsp. subtilis, B. subtilis subsp. spizizenii and B. vallismortis. The average nucleotide and translated amino acid similarities for the seve n type strains were 83.7 and 95.1%, respectively, whereas the corresponding value for the 16S rRNA sequences was 99.1%. All of the type strains were s harply separated; the closest relationship was found between B. atrophaeus and B. mojavensis which shared a nucleotide similarity of 95.8%. Phylogenet ic trees were inferred from gyrA nucleotide sequences using the neighbor-jo ining, Fitch-Margoliash and maximum parsimony algorithms. The test strains were divided into four groups, which generally reflected results previously reported in restriction digest and DNA-DNA hybridization studies. It is co ncluded from the comparative sequence analysis that the gyrA sequences prov ide a firm framework for the rapid and accurate classification and identifi cation of Bacillus subtilis and related taxa.