BClysin

Bacillus cereus is the second most frequent causative agent of confirmed and suspected foodborne outbreaks in France in 2020 and also an important spoilage microorganism in the food industry. Because of its ability to adhere to surfaces and form biofilm, B. cereus can lead to serious hygiene problems and economic loss due to food spoilage and equipment impairment. Current methods to eradicate biofilms are not always successful and some bacteria within the biofilm show a reduced susceptibility to antimicrobial agents due to their dormant phenotype. Therefore, the development of new antibacterial approaches targeting persister cells, non-toxic for humans and friendly for the environment, is of importance to control biofilm formation. Bacteriophage-derived lytic enzymes (endolysins) provide us with nearly ideal tools for the development of such strategy. Endolysins are peptidoglycan hydrolases characterized by an enzymatically active domain that catalyzes cell wall breakdown, and a cell wall-binding domain (CBD) that directs the enzymes to their substrates by recognizing specific cell wall-associated ligand molecules. BClysin project proposed, with an unbiased approach and multidisciplinary technics (genetic, bioinformatic, biochemistry, microscopy), to (i) identify genes implicated in endolysins ligands biosynthesis (CBD targets), by screening a transposon mutant library and a collection of B. cereus strains (ii) characterize genes identified and build a general scheme of the complex biochemical pathways that enable envelope assembly in B. cereus, leading to ligands endolysins identification (iii) Evaluate the antimicrobial effect of endolysins on B. cereus biofilms formation and disruption. This project will identify new targets to prevent Bc growth or biofilm formation and give new knowledge to develop tools to prevent and disrupt B. cereus biofilm in food industry in order to improve food safety.