6533b82bfe1ef96bd128d2c9

RESEARCH PRODUCT

Biogenesis and roles of Lacticaseibacillus casei BL23 membrane vesicles

subject

description

Gram-positive bacteria of the species Lacticaseibacillus casei (formerly known as Lactobacillus casei) are fermentative bacilli found in dairy products that are known for their anti-inflammatory properties and beneficial effects against pathogens. Like all living organisms, L. casei produces nanostructures of 20 to 400 nm in diameter bounded by a lipid membrane called membrane vesicles (MVs). MVs have been shown to contain various cellular constituents and exert multiple functions. However, despite the growing interest in Gram-positive MVs over the past 10 years, the mechanisms of biogenesis and the roles played by these vesicles remain poorly characterized. In this context, the objectives of this thesis project are (i) to characterize the MVs released by the L. casei strain BL23, (ii) to identify the biogenesis mechanisms and finally (iii) to study the roles played by these MVs. In this work, we demonstrated the production of MVs by L. casei BL23 using electron microscopy, then the size and protein composition of the purified MVs were examined. Based on the characterization results, the contribution of L. casei BL23 prophages to the biogenesis of MVs was investigated by a site-directed mutagenesis approach. Our results suggest a contribution of the PLE2 prophage in the production of MVs by L. casei BL23 in the absence or presence of genotoxic stress. Furthermore, we also showed that the MVs of L. casei BL23 exhibited an antibiofilm activity against several pathogenic and spoilage bacteria. These results pave the way for the use of MVs of L. casei BL23 to fight against the formation of bacterial biofilms.