Carlos Eduardo Serrano Maldonado
National Autonomous University of Mexico, Mexico
Title: Bacteriocin production by Enterococcus spp. strains isolated from cotija cheese
Biography
Biography: Carlos Eduardo Serrano Maldonado
Abstract
Cotija cheese is an artisanal mexican food produced from whole raw milk. No thermal step, neither starter cultures are used in the process. After a three month ripening stage, it presents an acceptable microbiological quality and no pathogenic bacteria have been detected in it. This could be caused by the production of antibacterial compounds by lactic acid bacteria (LAB), like peptidoglucan hydrolases and bacteriocins. The LAB genus most commonly isolated from Cotija cheese is Enterococcus and several strains have shown antibacterial activity against Listeria monocytogenes and Staphylococcus aureus. Enterocin A is a pediocin-like bacteriocin produced by some Enterococcus faecium and E. faecalis strains. It belongs to class IIa bacteriocins which display a high anti-listerial activity that could be interesting for application as a food bio-preservative. In this work seven Enterococcus strains were isolated from artisanal Cotija cheese, which were identified as E. faecalis (QA1 and QB3) and E. faecium (QC4, QD2, QE2, QG5 and A5-1). They are non-pathogenic and they showed antibacterial activity against Listeria monocytogenes by agar diffusion assay. A specific PCR reveals that six of the seven strains harbor the gene that codes for enterocin A (entA). Its expression was detected by identification of mRNA, Tris-Tricine gel electrophoresis and zymography. These strains have a biotechnological potential for their direct application in fermented foods or to produce antimicrobial peptides for food formulation.