Screening and Probiotic Property Analysis of High Exopolysaccharide-Producing Lactic Acid Bacteria from Sayram Yogurt

Exopolysaccharides (EPSs) produced by lactic acid bacteria (LAB) are bioactive polymers with significant potential for human health. This study aimed to isolate and systematically evaluate the in vitro probiotic properties of high exopolysaccharide-producing LAB strains from traditional Sayram yogurt. From fifteen strains, six strains with high exopolysaccharide production were identified using 16Sr DNA sequencing. We assessed their probiotic potential by testing acid resistance, bile salt tolerance, tolerance to artificial gastrointestinal fluid, self-aggregation, hydrophobicity, safety, antibacterial activity, and antioxidant capacity. Results showed these six strains exhibited a strong tolerance to acid, bile salts, and artificial gastrointestinal fluids, and had high self-aggregation abilities and surface hydrophobicity. The isolated strains exhibited varying degrees of sensitivity to the tested antibiotics, with no hemolysis, suggesting good safety. In addition, their cell-free supernatants significantly inhibited the growth of Staphylococcus aureus and showed stronger antioxidant activity than cell lysates. In conclusion, the six LAB strains screened in this study possess excellent in vitro probiotic properties and have potential value for further development, providing a preliminary strain reserve and theoretical reference for subsequent research and related product development.