Bacteriocinogenic anti-listerial properties and safety assessment of Enterococcus faecium and Lactococcus garvieae strains isolated from Brazilian artisanal cheesemaking environment

This study aimed to prospect and isolate LAB from an artisanal cheese production environment, to assess their safety, and to explore their bacteriocinogenic potential against Listeria monocytogenes. Samples were collected from surfaces of an artisanal-cheese production facility and after rep-PCR and 16S rRNA sequencing analysis, selected strains were identified to be belonging to Lactococcus garvieae (1 strain) and Enterococcus faecium (14 isolates, grouped into 3 clusters) associated with different environments (worktables, cheese mold, ripening wooden shelves). All of them presented bacteriocinogenic potential against L. monocytogenes ATCC 7644 and were confirmed as safe (γ-hemolytic, not presenting antibiotic resistance, no mucus degradation properties and no proteolytic or gelatinase enzyme activity). Additionally, cell growth, acidification and bacteriocins production kinetics, bacteriocin stability in relation to different temperatures, pH and chemicals were evaluated. According to performed PCR all studied strains generated positive evidence for presence of entA and entP genes (for production of enterocins A and enterocins P, respectively). However, pediocin PA-1 associated gene were recorded only DNA from E. faecium ST02JL and Lc. garvieae ST04JL. It is worth considering the application of these safe LAB or their bacteriocins in situ as an alternative means of controlling L. monocytogenes in cheese production environments alone or in combination with other antimicrobials.