Influence of Culturing Temperature on Bacteriocin Production and Safety Behavior on Bacteriocinogenic cocci With Antimicrobial and Probiotic Potential

The selection of novel probiotic candidates requires rigorous evaluation of safety and functional properties. This study aimed to assess safety, bacteriocin production and probiotic potential of four bacterial strains isolated from artisanal cheeses: Enterococcus faecium ST02JL and ST03JL, Lactococcus garvieae ST04JL, and Staphylococcus epidermidis ST0409KOC. Experiments were conducted at 37°C and 39°C to simulate physiological and thermal stress conditions. All strains were phenotypically safe, negative for gelatinase, hemolytic activity, and biogenic amine production, featured absence of virulence factors and antibiotic resistance genes. The isolates exhibited resilience to simulated gastrointestinal conditions and produced predominant L(+)-lactic acid. We evidenced the thermal modulation of bacteriocin activity; S. epidermidis showed a four-fold increase in anti-Listeria activity at 39°C. Resistance to vancomycin was dependent on culturing temperature. Our results demonstrate that the studied strains are safe for use in the dairy industry. Our findings confirmed that, under thermal stress, the biopreservative traits of S. epidermidis ST0409KOC are highly inducible.