The next species to consider in the B. subtilis species complex phylogeny are B. atrophaeus and B. mojavensis. As with the previously discussed two species, certain B. atrophaeus strains are potentially useful for industrial applications (Schmidt et al., 1979). Strains of B. atrophaeus typically produce dark brown to black pigments but are otherwise indistinguishable from B. subtilis and related species on the basis of other phenotypic, morphological, physiological or biochemical characteristics. B. mojavensis is a desert-adapted species and is similarly difficult to distinguish from B. subtilis, except for minor differences in cell-wall fatty acid content (Roberts et al., 1994). Two species described by Ruiz-Garcı ́a et al. (2005a), B. malacitensis and B. axarquiensis, were found to be very closely related to B. mojavensis, but Wang et al.reclassified these two species as later heterotypic synonyms of B. mojavensis. Similarly, the results of our phylogenetic analyses (Fig. 1 and Supplementary Fig. S1) show that strains NRRL B-41617T and NRRL B-41618T (the type strains of B. axarquiensis and B. malacitensis, respectively) cluster with the B. mojavensis type strain as well as another reference strain of that species.