Unveiling the probiotic potential of Enterococcus spp.: Mechanisms and roles in animal and human health, A comprehensive review.

Enterococci, a subset of lactic acid bacteria, are ubiquitous in a variety of ecosystems, including the gastrointestinal tracts of mammalian and avian species. Due to their extreme adaptability, enterococci thrive in exceptionally unfavorable conditions characterized by high salinity levels, exposure to bile salts, a wide range of pH variations and high-temperature thresholds. Investigation into enterococcal strains as potential probiotics has encompassed the fields of human health, animal husbandry and companion animal welfare. In the context of human applications, the objectives are related to increasing immune responses, reducing cholesterol levels and providing anti-inflammatory and antioxidant attributes. Similarly, the livestock sector has recognized the potential of enterococci to stimulate growth, inhibit pathogen proliferation and amplify immune reactivity. Pet health interventions using enterococci aim to balance the microbiota, boost immune function and improve the animal's general well-being. The mechanisms of probiotic effects mediated by enterococci are manifold, including the production of enterocins, improvement of cholesterol levels, immunomodulation, antioxidant activities, attenuation of inflammatory cascades and the support of liver functions. While enterococcal probiotics hold great promises for optimizing human and animal health, safety considerations must be taken into account. Given the pathogenic character of enterococci and their capacity to carry antibiotic resistance determinants, rigorous evaluation of safety profiles is an imperative prelude to their judicious use as probiotics.