Reidentification of facultatively alkaliphilic Bacillus firmus OF4 as Bacillus pseudofirmus OF4.

With a view toward verifying the original classification of alkaliphilic Bacillus firmus OF4, physiological and biochemical characteristics were more extensively catalogued than in original studies, and this catalog was supplemented with 16S rDNA sequence homology and more extensive DNA-DNA hybridization analyses. Phylogenetic analysis of this alkaliphile based on the comparison of multiple 16S rDNA sequences from Bacillus species indicated that this strain is most closely related to Bacillus pseudofirmus. Consistently, in the DNA-DNA hybridization analysis of the alkaliphile and Bacillus reference strains, the highest level of DNA-DNA relatedness (96%) was found between the alkaliphile and the B. pseudofirmus type strain (DSM 8715(T)). The findings support the conclusion that this alkaliphile strain is more closely related to B. pseudofirmus than to B. firmus, and we propose the future use of the designation B. pseudofirmus OF4.