Helicobacter pylori is a cause of gastric cancer. We extracted the exopolysaccharide (EPS) of Lactobacillus plajomi PW-7 for antibacterial activity versus H. pylori, elucidating its biological activity and structural characteristics. The minimum inhibitory concentration (MIC) of EPS against H. pylori was 50 mg/mL. Disruption of the cell membranes of pathogenic bacteria by EPS was indicated via the antibacterial mechanism test and confirmed through electron microscopy. EPS also has antioxidant capacity. The IC50 of EPS for 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical, superoxide anions, and hydroxyl radicals were 300 μg/mL, 180 μg/mL, and 10 mg/mL, respectively. The reducing power of EPS was 2 mg/mL, equivalent to 20 μg/mL of ascorbic acid. EPS is a heteropolysaccharide comprising six monosaccharides, with an approximate molecular weight of 2.33 × 104 Da. Xylose had a significant effect on H. pylori. EPS from L. plajomi PW-7 showed potential as an antibacterial compound and antioxidant, laying a foundation for the development of EPS-based foods.
Keywords: Helicobacter pylori; Lactobacillus plajomi; antibacterial activity; antioxidant activity; exopolysaccharide.