Exopolysaccharide Production by a Lactic Acid Bacteria, Leuconostoc lactis Isolated from Ethnically Fermented Beverage

Ethnic tribals of Northeast India are known to prepare local beverages using indigenous technology. Exopolysaccharide (EPS) producing lactic acid bacteria are responsible for the alteration of wine and other fermented beverages. Isolated from ethnically fermented beverage (Kyiad pyrsi), Leuconostoc lactis in the present study, was investigated for EPS production. EPS productions were evaluated on MRS sucrose media and Ruthenium red milk agar plate. It was found that L. lactis had the yield of EPS (340.82 mg/l) which was found to be lower than Leuconostoc mesenteroides reported from wine which produced 904 mg/l. Microtiter plate assay on biofilm of the isolates was used for optimization of EPS production. Fructose, glucose, galactose, mannose, lactose, sucrose and ribose were used as carbohydrate sources, while pH of 5.0, 5.5, 6.0, 6.5 7.0, 8.0 and temperatures of 28, 37 and 45 A degrees C were considered for production optimization. Sucrose, pH 6.5 and incubation temperature of 28 A degrees C were found to be optimal conditions for EPS production by the isolate.