Screening of High-yield Exopolysaccharide Lactic Acid Bacteria in Fermented Pickles in Changbai Mountain and Antioxidant Properties of Polysaccharides

This study aimed to screen lactic acid bacteria with high extracellular polysaccharide yield from fermented pickles, and the antioxidant activity of polysaccharide was studied in order to find a natural source of safe antioxidant. In this study, 160 lactic acid bacteria were isolated from more than 300 fermented pickles samples collected in Yanji City, where 10 lactic acid bacteria with high yield of exopolysaccharides were obtained according to the colony viscosity method. Finally, top three strains (A63, A120 and A128) were selected for further study. The crude exopolysaccharides were extracted and the yields were 0.806, 0.663 and 0.630 g/L, respectively. Moreover, all of the three strains were identified as Lactiplantibacillus plantarum by 16S rDNA and pheS gene sequence alignment analysis. The antioxidant activity of crude exopolysaccharides was evaluated by DPPH radical, ABTS⁺ radical and hydroxyl radical scavenging rate. The results showed that the exopolysaccharides of the three strains had higher ability to scavenge free radicals, where the scavenging rates of DPPH, ABTS⁺ and OH free radicals for L. plantarum A63 exopolysaccharides (10 mg/mL) were 90.47%, 51.67% and 35.08%, respectively, which was significantly higher than (P<0.05) that of other two kinds of exopolysaccharides at the same concentration, so it could be used as a potential source of natural antioxidants.