Antioxidant activity of exopolysaccharides from lacttic acid bacteria

Abstract

Despite of the great importance of lactic acid bacteria exopolysaccharides in both food and pharmaceutical industries they also play a critical role as potent antioxidânt. In this study, after the screening of nine strains for EPS production, four strains (Lb. curvatus Bj432, St. salivarius ssp thermophilus St.sa, Lactobacil/us sp. 05, Le. lactis ssp. cremoris CHT24) possessing high level were selected. Extracted EPS were further quantified and their antioxidant activity was evaluated. Lb. curvatus Bj432 acquired the highest amount of EPS (35.4mg/l) which exhibited the stronger DPPH free radical scavenging activity (61 %), besides, the higher hydroxyl radical scavenging activity (42%) was obtained by EPS from St. salivarius ssp thermophilus St.sa. However, all extracted EPS have shown excellent iron ion chelating ability (70-75%). Furthermore, in order to be qualified as probiotic strain, the survival rate under acidic conditions (pH 2.0) and 1 % bile salt during 4h of Lactobacillus sp. 05 was evaluated, obtained results showed good tolerance in both cases .