Exploring Safety and Antioxidant Activity of Lactiplantibacillus plantarum F190 and Optimizing Its Exopolysaccharide...

Lactiplantibacillus plantarum F190 with an exopolysaccharide (EPS) yield of 513.38 mg/L was screened from strains isolated from traditional dairy products in Xinjiang, China. In vitro safety evaluation showed that this strain was nonhemolytic, sensitive to common antibiotics, and exhibited low biogenic amine formation. Whole-genome sequencing provided supportive evidence for its favorable safety profile through analyses of virulence factor and antibiotic resistance genes. In vitro antioxidant assays suggested that the fermented supernatant (FS) might serve as a primary active fraction contributing to the antioxidant activity of strain F190, with its DPPH, ABTS, and hydroxyl radical scavenging rates measured at 87.93 ± 0.11%, 37.49 ± 0.36%, and 49.81 ± 1.42%, respectively; EPS-2, purified from F190-EPS, could be an important bioactive fraction exerting antioxidant activity in F190-EPS and was observed to possess radical scavenging capacities of 72.58 ± 0.97% for ABTS, 50.48 ± 0.77% for DPPH, 49.02 ± 0.59% for hydroxyl radical, and 45.22 ± 1.47% for superoxide anion. The fermentation conditions for EPS production were optimized through single-factor experiments and response surface methodology with EPS yield as the response variable, resulting in a 36.97% increase in EPS yield. This study provides a theoretical foundation for the industrial production of EPS from L. plantarum F190 and the application of its antioxidant potential.