Screening of Exopolysaccharide-producing Lactobacillus Strains and Study of Exopolysaccharide Properties
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Abstract:
Exopolysaccharide (EPS)-producing Lactobacillus strains were screened from the digestive glands of seafood from the Dalian area, and the functional properties of the produced EPSs were studied. One target strain was selected, the corresponding EPS was isolated and purified, and the relative molecular weights of all purified polysaccharide components were measured. Strains with relatively high EPS-producing ability were identified as Lactobacillus plantarum subsp. plantarum-4, Lactobacillus plantarum-12, and Lactobacillus plantarum subsp. plantarum-49. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging abilities of the three Lactobacillus plantarum strains and their EPSs were measured. When the EPS produced by Lactobacillus plantarum-12 was at a concentration of 0.5 mg/mL, the DPPH free radical scavenging rate was 48.82±3.88%, significantly higher than those of other two strains (p<0.05). The effect of EPS produced by Lactobacillus plantarum strains on the inhibition of the adhesion of Escherichia coli ATCC 25922 to HT-29 cells was measured. When the EPS produced by Lactobacillus plantarum-12 was at a concentration of 0.2 mg/ml, the inhibitory rate was 78.23%±2.46%, significantly higher than those of other two strains (p<0.05). The EPS produced by Lactobacillus plantarum-12 could significantly inhibit IL-8 production by HT-29 cells stimulated by E. coli ATCC 25922 (p<0.05). The crude EPS produced by Lactobacillus plantarum-12 was purified by DEAE-Sepharose anion-exchange, Sepharose CL-6B, and Sephacryl HR S200 chromatography columns; two fractions were obtained, and their relative molecular weights were 8.5×104 u and 7.4×104 u.
