Submitted to: International Journal of Systematic and Evolutionary Microbiology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/23/2008
Publication Date: 10/1/2009
Citation: Rooney, A.P., Price, N.P., Erhardt, C., Swezey, J.L., Bannan, J.D. 2009. Phylogeny and Molecular Taxonomy of the Bacillus subtilis species Complex and the Description of Bacillus subtilis subsp. inaquosorum subsp. nov. International Journal of Systematic and Evolutionary Microbiology. 59(Pt 10):2429-2436. Interpretive Summary: This manuscript describes work on the taxonomy of bacteria species within the genus Bacillus that have agricultural, biomedical and/or biotechnological significance. The existence of two new species was uncovered by this research, and formal species descriptions were reported in the manuscript. In addition, a novel molecular phylogenetic framework was developed for the recognition of Bacillus species, facilitating current and future research efforts by scientists working to identify novel strains of Bacillus for various agricultural or biotechnological purposes.
Technical Abstract: The Bacillus subtilis species complex is a tight assemblage of closely related species. For many years, it has been recognized that these species cannot be differentiated on the basis of phenotypic characteristics. Recently, it has been shown that phylogenetic analysis of the 16S ribosomal RNA gene also fails to differentiate species within the complex due to the highly conserved nature of the gene, yet DNA-DNA hybridization values fall well below 70% for these same species comparisons. As a complimentary approach, we propose that phylogenetic analysis of multiple protein-coding loci can be used as a means to define Bacillus species. In applying this approach, we show that the use of the subspecies rank for B. s. subtilis and B. s. spizizenii should be abandoned in order to avoid rendering B. subtilis paraphyletic. Instead, B. s. spizizenii should be recognized as a distinct species and a closely related clade newly identified in this study should be recognized as a novel taxon, B. inaquosus.