A review on the ecological niche and functional properties of enterococci in health promotion.

Enterococci are ubiquitous lactic acid bacteria (LAB) that mainly inhabit the gastrointestinal tracts of humans and animals and are also widely present in foods and the environment due to their robust survival capacity. While many studies have focused on their pathogenic potential, increasing attention is being given to their probiotic properties. In this review, we summarized the ecological niches of enterococci in the genus, habitats, and food systems, and comprehensively discuss their functional metabolites, including organic acids, enterocins, exopolysaccharides, and surface layer proteins, as well as their roles in fermentation and health promotion, such as inhibiting Listeria monocytogenes, alleviating metabolic disorders, hypercholesterolemia, and cancer development. Importantly, unlike previous reviews that emphasized pathogenesis with only a brief mention of probiotic traits, this review provides an integrated and mechanism-oriented perspective on enterococci as probiotics, and highlights future research directions, including their interactions with food matrices and host gastrointestinal systems, as well as the application of artificial intelligence and machine learning for the rigorous screening of safe enterococcal probiotics.