Fig. 3

PCA clustering of B. cereus group isolates based on virulence gene presence/absence. PCA analysis was carried out using the data on presence/absence of 30 virulence genes that had variable presence across the analyzed 69 isolates. Reference isolates are color-coded according to the previously identified species, and all 22 dairy-associated isolates are labeled as “B. cereus group”. The figure demonstrates clustering of analyzed isolates based on the PC 1 (x axis), PC 4 (y axis) and PC 3 (dot size). PC 2 was omitted, as it specifically characterized a single isolate carrying genes that encode the cereulide biosynthetic pathway. The B. cereus and B. anthracis and B. cereus isolates carrying anthrax toxin and poly-γ-D-glutamate capsule genes form a clearly separated group on the bottom left side of the figure, while environmental isolates and B. cytotoxicus tend to cluster on the upper right side. Isolates carrying genes associated with diarrheal foodborne disease cluster on the bottom right side