Bioprotective Effect of a Bacteriocin-Producing Lactococcus lactis Strain Against Enterococcus faecium Isolated from Egyptian Tallaga Cheese

<b>Background/Objectives</b>: Tallaga cheese is an artisanal form of traditional Egyptian soft white Damietta cheese, characterized by high moisture, elevated salinity, and a limited shelf life, which collectively increase its vulnerability to microbial contamination. Typically produced from raw or minimally heated cow or buffalo milk, Tallaga cheese represents a relevant model for studying emerging food safety challenges. <b>Methods/Results</b>: This study revealed marked variability among commercial samples and, unexpectedly, a general absence of typical lactic acid bacteria (LAB) such as <i>Lactococcus</i> spp. Instead, enterococci, microorganisms increasingly associated with antimicrobial resistance and virulence traits, emerged as the dominant LAB group, with the detection of <i>Enterococcus faecium</i> strains posing particular concern for dairy safety. To address these challenges, the antimicrobial potential of isolated LAB was evaluated against <i>Latilactobacillus sakei</i> (CECT 906). Twelve bacteriocin-producing strains were identified: ten <i>Enterococcus faecalis</i>, one <i>E. faecium</i>, and one <i>Lactococcus lactis</i>. Enterococci demonstrated robust tolerance to stress conditions, including high salt concentrations, emphasizing their persistence in dairy environments. Given the relevance of controlling resistant and potentially virulent strains such as <i>E. faecium</i>, the bioprotective capacity of two bacteriocinogenic <i>L. lactis</i> strains (IPLA 1064 and AHRI ST9) was assessed using a laboratory-scale cheese model. Both strains effectively inhibited <i>E. faecium</i> AHRI CH4, achieving reductions of 2.6 and 3.6 log units (99.9%). <b>Conclusions</b>: These findings underscore the relevance of bacteriocin-producing <i>L. lactis</i> as natural biopreservatives to mitigate emerging threats related to antimicrobial-resistant food-borne pathogens in dairy products.