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Title: RELATIONSHIP OF BACILLUS SUBTILIS CLADES ASSOCIATED WITH STRAINS 168 AND W23: A PROPOSAL FOR BACILLUS SUBTILIS SUBSPECIES SUBTILIS AND BACILLUS SUBTILIS SUBSPECIES SPIZIZENI

Author
item Nakamura, Lawrence
item ROBERTS, M - MICHIGAN STATE UNIVERSITY
item COHAN, F - WESLEYAN UNIVERSITY

Submitted to: International Journal of Systematic and Evolutionary Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/8/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary: A number of bacteria were isolated from desert environments. Preliminary studies suggested that these organisms belong to a species named Bacillus subtilis and consist of two subgroups. Interbreeding studies, comparison of genetic (gene) structures, and measurement of chromosomal (genetic) similarity confirmed that Bacillus subtilis was made up of two closely related but unique genetic subgroups. Interestingly, these subgroups were closely related to two historically important strains named W23 and 168.

Technical Abstract: Earlier phylogenetic studies based on the inferred DNA sequences of the polC, rpoB, and gyrA genes suggested that Bacillus subtilis was a composite of two closely related taxa, one containing laboratory strain 168 and another containing laboratory strain W23. Significant sexual isolation was found between strain 168 and members of the group containing W23, but there was no sexual isolation between strain 168 and other members of the 168 group. The extent of DNA reassociation between the two groups ranged from 58 to 69%, and intragroup DNA relatedness ranged from 82 to 100%. Because group 168 strains were highly related to the B. subtilis type strain, they were considered bona fide members of the species. About 99.5% sequence identity was observed between 16S rRNA gene of the 168 and W23 groups. These observations revealed two closely related but genetically distinct groups within Bacillus subtilis which correspond to two historically important strains. Subspecies distinction is proposed for th 168 and W23 groups, with the names Bacillus subtilis subsp. subtilis and Bacillus subtilis subsp. spizizeni, respectively.