Taxonomy of alkaliphilic Bacillus strains

The DNA base compositions of 78 alkaliphilic Bacillus strains were determined. These strains were grouped as follows: DNA group A, guanine-plus-cytosine (G+C) content of 34.0 to 37.5 mol% (17 strains); DNA group B, G+C content of 38.2 to 40.8 mol% (33 strains); and DNA group C, G+C content of 42.1 to 43.9 mol% (28 strains). DNA group A includes the type strain of Bacillus alcalophilus Vedder 1934. DNA-DNA hybridization studies with DNA group A strains revealed that only one strain, strain DSM 2526, exhibited a high level of DNA homology with B. alcalophilus DSM 485T (T = type strain). Neither strain DSM 485T nor any other DNA group A strain is homologous to any of the Bacillus type strains with comparable base compositions. Six strains formed a distinct group containing three highly homologous strains and three strains exhibiting greater than 50% DNA homology.