The species B. amyloliquefaciens is the next to branch off from the remainder of the B. subtilis species complex (Fig. 1 and Supplementary Fig. S1). B. amyloliquefaciens is an industrially important species that is used for a number of applications, most notably for the production of a-amylase. Recently, Ruiz-Garcı ́a et al. (2005a) described a group of strains closely related to B. amyloliquefaciens as representing a novel species, B. velezensis. The latter is also potentially valuable to a number of industries, as certain strains were shown to produce high levels of surfactins. However, Wang et al. (2008) reclassified B. velezensis as a later heterotypic synonym of B. amyloliquefaciens on the basis of DNA–DNA hybridization data. In our study, B. amyloliquefaciens and B. velezensis (NRRL B-41580T) were found to be very closely related and could not be reliably differentiated from one another or other B. subtilis complex species without the use of gene sequence data.