CONICET | Buscador de Institutos y Recursos Humanos

Archaea, bacteria, and eukaryotes secrete extracellular vesicles (EVs) as a mechanismfor intercellular communication. We reported the isolation and characterization of EVsfrom the Lacticaseibacillus casei BL23, a strain that exhibits probiotic properties. Using aproteomic approach (LC-MS), we identified a total of 103 proteins; 13 exclusivelypresent in the EVs. The EVs content included cell envelope associated and secretoryproteins, heat and cold shock proteins, several metabolic enzymes, proteases, structuralcomponents of the ribosome, membrane transporters, cell wall-associated hydrolasesand phage-related proteins. We identified proteins described as mediators ofLacticaseibacillus probiotic effects such as p40, p75 and the product of LCABL_31160,annotated as an adhesion protein. More recently, we conducted LC-MS/MS (tandemmass spectrometry) analysis of L. casei BL23 EVs. Only six major EV protein bands wereexcised to reduce the complexity of the sample and thus improve the sensitivity of thetechnique. Bands were in gel-digested, and tryptic peptides were separated by 1DULTRA nanoLC and analyzed by a mass spectrometer nanoESI qQTOF. Aftercomparison against protein databases in ProteinPilot v 5.0 software, the mostabundant identified bands corresponded with membrane proteins, cell wall hydrolasesand enzymes involved in metabolic pathways. Some of the latter, such as GAPDH andenolase, were reported to translocate to the surface of lactobacilli, where they canfunction as adhesins, and enhance the adhesion of EVs to the intestine. The presenceof these proteins suggests a role for the EVs in the bacteria-gastrointestinal cellsinterface. Studies are being carried out by our group to confirm the presence of theseproteins and shed light on how probiotics have beneficial effects on the host.