Production, partial characterization and antioxidant properties of exopolysaccharide α-d-glucan produced by Leuconostoc lactis KC117496 isolated from an idli batter.

Exopolysaccharide (EPS) produced from Leuconostoc lactis KC117496 isolated from the naturally fermented idli batter has been reported earlier. Here, study aimed to optimize the carbon source to enhance the yield of EPS production, partial characterization and antioxidant activity of α-d-glucan EPS. Among different disaccharides (sucrose, maltose, lactose) and monosaccharides (glucose, galactose and fructose), combination of sucrose and glucose at 2% showed highest EPS production of 4.55 g/L in MRS medium. The molecular weight was identified as ~ 4.428 × 103 kDa with MALDI-TOF mass spectroscopy. 1D and 2D NMR results exhibited the presence of α-1-6 and α-1-3 linked glucose revealed EPS as a glucan. Antioxidant properties of glucan (500 µg/mL) revealed the significant oxidation alleviation potential such as DPPH (74%) and Hydroxyl radical activity (97.8%), whereas metal chelating activity (70%) was lower as compare to control standard. These characteristics of glucan EPS reveals its potential application in food and pharmaceutical industry.