Priestia flexa KS1: A new bacterial strain isolated from human faeces implicated in mucin degradation

The human gut acts as a habitat for diverse microbial communities, including mucin utilizers that play a significant role in host health and diseases. In this study, a gram-positive, rod-shaped mucin degrading bacterium was isolated from human faeces that belonged to the Priestia flexa species. Priestia isolate was analyzed for mucin-degrading ability and found that the KS1 strain could grow on mucin as the sole carbon source. The experimental results of the mucolytic zone around the colony and a 58% decrease in carbohydrate concentration confirmed the ability of Priestia to degrade mucin. The intracellular and extracellular glycosidase assay data supported the above results suggesting the ability of P. flexa to produce glycan hydrolysis enzymes that convert complex mucin oligosaccharide chains into simple glycans. The survival ability of the KS1 strain in simulated gastrointestinal conditions revealed that it could tolerate low pH (≥ 50% cell viability at pH 1.0) and 0.5% bile salt concentration (≥ 85% cell viability). The strain showed low hydrophobicity towards n-hexadecane (26.51 ± 0.92%) and xylene (21.71 ± 0.54%). Moreover, the KS1 culture was resistant to cefixime, clavulanic acid/ceftazidime, nafallin, methicillin, trimethoprim, kanamycin, and nalidixic antibiotic. Our results highlight the isolation of P. flexa KS1 strain that degrade mucin under in vitro conditions and show its better acclimatization within the GI environment. Further studies are required to unearth the molecular mechanisms involved in the degradation of mucin oligosaccharides in the human gut, advancing our understanding of health and disease.