Chapter 2 – Bacillus cereus Group Diagnostics: Chromogenic Media and Molecular Tools

The genus Bacillus comprises a highly heterogeneous endospore-forming group of bacteria. Owing to their ubiquity, the spores represent the most important contaminating form of these bacteria. Bacillus spores can contaminate food production at diverse stages, becoming a potential risk to consumers because certain strains may produce various toxins. However, other diseases are also due to Bacillus species, such as anthrax and skin, wound, and systemic infections. For this reason, not only in food microbiological diagnostics, conventional culture-based methods have been proposed, standardized by International Organization for Standardization or Food and Drug Administration protocols, for a conventional diagnostic. The DNA-based identification methods, which have increased since 1995 in diagnostic microbiology and have diffused into laboratory routine analysis, have shown a high genetic heterogeneity within the genus Bacillus at the species and strain levels, highlighting the importance of the virulence factor. For this reason, DNA-based methods have been utilized more and more, accompanying the classical culture methods. Culture and chromogenic media, biochemical approaches, and molecular tools will be treated in this chapter, focusing on their diversity, sensitivity, and capacity, not only for species identification, but also for revealing toxic and nontoxic strains.