A sapropel-derived Lactiplantibacillus plantarum with antimicrobial activity improves intestinal architecture and remodels gut microbiota.

Identifying safe probiotic strains with potent antimicrobial activity is essential for the development of next-generation microbial therapeutics. Here we report a novel sapropel-derived strain, Lactiplantibacillus plantarum (L. plantarum) JH-N1, exhibiting antibacterial activity together with favorable probiotic traits. In vitro safety evaluation showed no mucin degradation, β-haemolytic activity or cytotoxic effects on Caco-2 cells. L. plantarum JH-N1 displayed marked tolerance to simulated gastrointestinal stress, surviving exposure to pH 2 and bile salts, and showed strong cell-surface hydrophobicity, auto-aggregation and co-aggregation with multiple pathogens. The strain also adhered efficiently to Caco-2 cells and remained susceptible to most clinically relevant antibiotics. In vivo, acute and subacute toxicity studies in mice revealed no adverse effects on body weight, organ indices, tissue histology, hematological parameters or serum biochemical markers. Notably, L. plantarum JH-N1 improved intestinal morphology by promoting villus development and increasing crypt depth in multiple gut segments. Moreover, administration of L. plantarum JH-N1 reshaped the gut microbiota, increasing beneficial bacterial populations while reducing potentially harmful taxa. Together, these findings identify L. plantarum JH-N1 as a safe and functionally robust probiotic candidate with promise for animal husbandry and biomedical applications.