Phylogenetic analysis of transformable strains of thermophilic Bacillus species

Few strains of thermophilic Bacillus spp are readily transformable with pla smid DNA. Given the considerable phylogenetic and phenotypic diversity amon gst thermophilic bacilli, we have examined whether transformability is a tr ait associated with a particular phylogenetic group, by sequencing the 16S ribosomal RNA genes from transformable strains NUB3621, K1041, and NRRL1174 . Although all of these strains were described in the literature as B. stea rothermophilus, only NRRL1174 is closely related to the type strain of this species. Based on its 16S rDNA sequence and physiological data K1041 appea red to belong to the species B. thermodenitrificans, while NUB3621 showed a slightly closer relationship to B. thermoglucosidasius than to B. stearoth ermophilus. Therefore we conclude that the trait of transformability, thoug h possibly strain-specific, is not limited to a single species of thermophi lic Bacillus. (C) 1999 Federation of European Microbiological Societies. Pu blished by Elsevier Science B.V. All rights reserved.