Correlation of 16S ribosomal DNA signature sequences with temperature-dependent growth rates of mesophilic and psychrotolerant strains of the Bacillus cereus group

Sequences of the 16S ribosomal DNA (rDNA) from psychrotolerant and mesophil ic strains of the Bacillus cereus group revealed signatures which were spec ific for these two thermal groups of bacteria. Further analysis of the geno mic DNA from a wide range of food and soil isolates showed that B. cercus g roup strains have between 6 and 10 copies of 16S rDNA. Moreover, a number o f these environmental strains have both rDNA operons with psychrotolerant s ignatures and rDNA operons with mesophilic signatures, The ability of these isolates to grow at low temperatures correlates with the prevalence of rDN A operons with psychrotolerant signatures, indicating specific nucleotides within the 16S rRNA to play a role in psychrotolerance.