The Bacillus cereus sensu lato group comprises six related species: B. cereus, B. anthracis, B. thuringiensis, B. mycoides, B. pseudomycoides and B. weihenstephanensis. Bacillus thuringiensis is a mesophile. It is distinguished from other members of the B. cereus group by the apparition of an inclusion body upon sporulation. B. weihenstephanensis, however, is a psychrotolerant. It grows at 7 degrees C but not at 43 degrees C. It is further characterised by the presence of specific signature sequences on two genes, the 16S rRNA gene (the small subunit ribosomal RNA gene) and cspA (encoding the major cold shock protein). Five B. thuringiensis serovars selected from previous studies, bolivia, vazensis, navarrensis, azorensis and asturiensis were studied here for their capability to grow at 7 degrees C but not at 43 degrees C. Next, their 16S rRNA and cspA genes were analysed for the presence of B. weihenstephanensis-specific signature sequences. Bacillus thuringiensis serovars bolivia, vazensis and navarrensis met the description of B. weihenstephanensis.