speculated about an uncommon specific niche for the moderate thermotolerant group VII Bacilli (i.e.B. cytotoxicus). In our study B. cytotoxicus was isolated from one sample
of raw potatoes (product category E in Table 1). Although being far from
statistically relevant, this finding rather supports the assumption that
the natural habitat of B. cytotoxicus could be the soil and consequently
that potatoes can be considered to be a likely source for this species in
the samples tested in this study. A possible explanation for the fact
that B. cytotoxicus had so far only rarely been identified and reported
could be its phenotypic resemblance as well as its biochemical close
relatedness to B. cereus. Strains isolated according to Anonymous,
2004, the official method for the isolation of B. cereus from food, are
summarised under the term “presumptive B. cereus”, a collective name
comprising B. cereus sensu stricto, B. thuringiensis and other closely
related Bacilli. Hence B. cytotoxicus might usually just be subsumed
under the label of “presumptive B. cereus”. Moreover, B. cytotoxicus is
probably overgrown by the present plant and/or soil flora in food
samples incubated under standard conditions (i.e. 30 °C), making incubation
at 50 °C an important selective step.