Functional Insights of Mucin Foraging Enterococcus durans G322S from Healthy Human Feces

The human gastrointestinal tract is a home to several novel, diverse and complex microbial species that maintain a commensal relationship with the host. In this study, a Gram-positive, cocci-shaped mucin-degrading bacterium was isolated from human feces and identified as Enterococcus durans G322S, which can utilize mucin as the sole carbon source. The qualitative data in the form of a halo around the colony confirmed the mucolytic activity and quantitative degradation evident 70 ± 2.1% decrease in oligosaccharide content and 35 ± 2.9% protein content. The extracellular glycosidase activities data further supported the notion regarding the involvement of enzymes in degradation of mucin glycans. Notably, this study moves beyond conventional mucin degradation isolation by functionally characterizing a safe, mucus-adapted strain with promising probiotic attributes. The G322S strain exhibited no virulence traits, i.e., hemolysis, gelatinase, biofilm, and exopolysaccharide production (EPS). It survived well under simulated gastrointestinal conditions and exhibited survivability at low pH (40–55%) and high bile salt concentrations (≥ 60% cell viability). Moreover, the strain showed considerable in vitro binding to mucin (~15%) and low antibiotic resistance rate (16.3%). It showed antagonistic activity ranging from 12–19 mm against Staphylococcus lentus, Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa. These integrated functional traits such as mucin foraging, enzymatic profile, antimicrobial activity, and safety, collectively suggest E. durans G322S as a promising next-generation probiotic candidate for mucus niche. Further work is needed to unearth the molecular mechanisms underpinning the degradation of mucin oligosaccharides in the human gut and their consequences on the microbial flora.