Staphylococcus warneri MN336185 from Fermented Rice Water: a Multifunctional Probiotic with Anti-pathogenic and...

Fermented ecosystems serve as critical reservoirs for functionally diverse microorganisms with applications in food safety and nutraceuticals. This study focuses on Staphylococcus warneri MN336185 (SW), a non-traditional probiotic strain isolated from fermented rice water and evaluating its probiotic and bio-preservative properties. SW demonstrated significant gastrointestinal and oxidative stress tolerance, high epithelial cytocompatibility (> 80%), non-hemolytic safety, and an exceptional cholesterol assimilation efficiency of 85%. Moreover, whole-genome sequencing (WGS) confirmed genomic biosafety, establishing the absence of acquired enterotoxins, superantigens, ica-dependent biofilm determinants, and most transmissible antibiotic resistance elements. Studies on the host-microbe interface confirmed strong adherence of SW to HT-29 cells with proportionate competitive anti-adhesion potential against Salmonella enterica and Escherichia coli. The strain could also upregulate tight-junction proteins, claudins and zona occludens, indicating barrier-protective effects. In Caenorhabditis elegans, supplementation of SW as live feed enhanced lifespan, pharyngeal pumping, locomotory abilities, and resistance to pathogens. Further, challenge tests involving incorporation of live cells or cell-free supernatant of SW into rice-based matrices resulted in significant, time-dependent reduction of pathogens with a 4 log₁₀ CFU decrease during refrigerated storage. Collectively, these observations could establish S. warneri MN336185 as a multifunctional probiotic strain with potential application in functional food and natural biopreservation strategies.