The Bacillus cereus group is now attracting the greatest interest among researchers working on bacilli and other gram-positive bacteria. One of the fundamental and practical questions being asked is how the ecological adaptation of these bacteria results in pathogens for animals and insects (like B. anthracis or some B. thuringiensis lines). This has inspired intensive phylogenetic studies, revealing the epidemic structure of this bacterial population. B. cereus includes strains that are presumably innocuous (some strains are used as animal probiotics) and strains that have caused food poisoning, either emetic or diarrheic. All emetic strains, as well as B. anthracis, seem to represent a single clone, but at the moment, diarrheic strains cannot be easily discriminated from one other. The existence of foodborne pathogenic strains and psychrotrophic strains (i.e., strains able to live at low temperatures) within the same cluster is the real challenge for food safety.
Genomic studies of several representatives of this group have started to unveil the subtle features of genome organization that may be related to pathogen emergence. Gathering more such data will certainly inspire new ideas about the short time evolution of these bacteria, which should allow scientists to predict, and if necessary to stop, its potential pathogenic emergence. There is a large research community studying B. cereus, B. anthracis, and B. thuringiensis, and the scope of issues being studied is very broad. The B. cereus group, representing important insect and animal pathogens, raises specific practical questions about phylogeny, ecology, bacterium-host interactions, pathogen-related regulation, and stress resistance.
CSP project participants: Alexei Sorokin (proposer), S. Dusko Ehrlich, Didier Lereclus, Vincent Sanchis Stéphane Aymerich, Michel Gohar, Christophe Nguyen-the, Veronique Broussole, (INRA, France); Michio Ohta and Keizo Torii (Nagoya Univ.); and Ken Kurokawa (Osaka Univ.).