Probiotic potential of Enterococcus faecalis CAUM157 Probiotic potential and safety assessment of bacteriocinogenic Enterococcus faecalis CAUM157

Arxel G. ElnarGeun-Bae Kim^*

• Chung-Ang University, Seoul, Republic of Korea

The potential of bacteriocin-producing Enterococcus faecalis CAUM157 (KACC81148BP), isolated from raw cow's milk, was examined as a probiotic strain. Genomic analyses revealed virulence factors associated with adhesion, biofilm formation, and anti-phagocytosis. Various enzymes and antimicrobial resistance genes that confer resistance to aminoglycosides, lincosamides, macrolides, streptogramins A and B, and tetracyclines were also identified.Although generally regarded as detrimental, virulence factors are crucial to colonization, niche establishment, and subsequent manifestation of the beneficial effects of the strain, as evident in other probiotic lactic acid bacteria. Notably, CAUM157 was sensitive to clinically important antibiotics like ampicillin (MIC, 4.0 µg/mL) and vancomycin (MIC, 1.0 µg/mL), congruent with its ST21 MLST typing. CAUM157 survived in acidic conditions (pH 3.0 and pH 2.0) with 100.72 ± 0.20% and 97.28 ± 2.19% survival rates, respectively, and showed high survival rates when exposed to 0.3% (104.16 ± 3.42%) and 0.5% (90.65 ± 1.22%) bile extract, attributed to the enzymatic activity of bile salt hydrolase. CAUM157 also exhibited robust auto-aggregation and co-aggregation when interacting with Listeria monocytogenes. Finally, the ability to produce a broad-spectrum bacteriocin in conjunction with other factors indicates a potentially efficient mechanism for mitigating the pathogenicity of detrimental bacteria, including Staphylococcus aureus, Clostridium perfringens, and Streptococcus mutans. Overall, E.faecalis CAUM157 may be a potential probiotic candidate in the food and feed industries.