The megaplasmid pCER270 of <i>Bacillus cereus</i> emetic strain affects the timing of the sporulation process, spore resistance properties, and germination

The acquisition of new mobile genetic elements, such as plasmids, is essential for the pathogenesis and adaptation of bacteria belonging to the <i>Bacillus cereus</i> group. This can confer new phenotypic traits and beneficial functions that enable bacteria to adapt to changing environments and colonize new ecological niches. Emetic <i>B. cereus</i> strains cause food poisoning linked to the production of cereulide, the emetic toxin whose synthesis is due to the presence of plasmid pCER270. In the environment, cereulide provides a competitive advantage in producing bacteria against various competitors or predators. This study demonstrates that pCER270 also regulates the sporulation process, resulting in spores with improved heat resistance and germination capacity. The transfer of plasmid pCER270 among different strains of the <i>B. cereus</i> group may enhance their adaptation to new environments. This raises the question of the emergence of new pathogenic strains, which could pose a serious threat to human health.