Genomic and phenotypic characterization of type strains and dairy-associated isolates in the Bacillus cereus group indicates considerable intra-clade variability in toxin production and cytotoxicity.

Genomic and phenotypic characterization of type strains and dairy-associated isolates in the Bacillus cereus group indicates considerable intra-clade variability in toxin production and cytotoxicity. Appl Environ Microbiol. 2018 Jan 12;: Authors: Miller RA, Jian J, Beno SM, Wiedmann M, Kovac J Abstract While some species in the B. cereus group are well-characterized human pathogens (e.g., B. anthracis and B. cereus s.s.), the pathogenicity of other species (e.g., B. pseudomycoides) either has not been characterized or is presently not well understood. To provide an updated characterization of the pathogenic potential of species in the B. cereus group, we classified a set of 52 isolates, including 8 type strains and 44 environmental isolates from dairy-associated sources, into 7 phylogenetic clades and characterized them for (i) the presence of toxin genes, (ii) phenotypic characteristics used for identification, and (iii) cytotoxicity to human epithelial cells. Overall, we found that B. cereus toxin genes are broadly distributed, but are not consistently present within individual species and/or clades. After growth at 37°C, isolates within a clade did not typically show a consistent cytotoxicity phenotype, except for clade VI (B. weihenstephanensis/mycoides), where none of the isolates were cytotoxic, and isolates in clade I (B. pseudomycoides), which consistently displayed cytotoxic activity. Importantly, our study highlights that ...
Source: Applied and Environmental Microbiology - Category: Microbiology Authors: Tags: Appl Environ Microbiol Source Type: research