Evaluation of probiotic properties and genome analysis of the new Pediococcus acidilactici strain 46A isolated from Chinese young adults: in vitro and in vivo studies

Background: The human gut microbiota plays a key role in intestinal homeostasis and inflammatory diseases, prompting the search for novel probiotic strains with strain-specific functional properties. Dierences in dietary habits and cultural backgrounds represent a valuable source for isolating previously uncharacterized gut bacteria. Given the increasing use of probiotics, rigorous safety assessment, including antimicrobial resistance (AMR) evaluation, is required, and the integration of whole-genome sequencing with phenotypic characterization is recommended. Objectives: This study evaluated the probiotic potential of Pediococcus acidilactici strain 46A, isolated from fecal samples of healthy Chinese student volunteers, through whole-genome analysis and in vitro and in vivo functional assessments. Methods: Strain identification was performed by MALDI-TOF mass spectrometry and 16S rRNA gene sequencing. In vitro assays assessed tolerance to simulated gastrointestinal conditions, bile salt resistance, antimicrobial activity, and adhesion to HT-29 intestinal epithelial cells. Whole-genome sequencing was used to evaluate safety- and functionality-related genetic traits. The protective eect of P. acidilactici 46A was investigated in a dextran sulphate sodium (DSS)-induced murine model of colitis, including histological evaluation, inflammatory marker analysis, and gut microbiota profiling. Results: P. acidilactici 46A showed high survival under simulated gastrointestinal conditions and bile exposure, antimicrobial activity against Gram-positive and Gram-negative bacteria and yeasts, and strong adhesion to HT-29 cells compared with other tested strains. Genomic analysis confirmed the absence of virulence factors and clinically relevant antibiotic resistance genes. In DSS-treated mice, oral administration of P. acidilactici 46A significantly reduced colitis severity, preserved colonic mucosal architecture, and decreased inflammatory markers, including IL-1β and IL-6. Conclusion: Pediococcus acidilactici 46A is a safe and functionally active probiotic candidate that attenuates intestinal inflammation and preserves mucosal integrity in a murine model of colitis, supporting its potential application in the prevention or adjunctive treatment of inflammatory gut disorders.