Fermentation Characteristics of Exopolysaccharide-Producing Lactic Acid Bacteria from Sourdough and Assessment of the Isolates for Industrial Potential

Lactic acid bacteria (LAB) with antimicrobial activity and high exopolysaccharide (EPS) production ability isolated from sourdough were studied for their fermentation characteristics as potential new starter cultures. The values of pH, titratable acidity, and viable cell counts were log CFU/ml, respectively. In order to select probiotics with a high survival rate in the gut, isolates were tested to assess resistance against the artificial gastric acid and bile juice. Viable LAB counts were significantly (p0.07 log for S. thermophilus St-Body-1, >7.980.03 log for E. flavescens DU-10, >7.950.05 log for E. faecium DU-12, and 3.150.06 log for L. amylovorus DU-21. Among the strains, L. amylovorus DU-21 was the only strain that had bile tolerance under simulated gastrointestinal conditions. In order to improve EPS production by L. amylovorus DU-21, the influence of carbon source was studied. When glucose was used as a carbon source, EPS production dramatically increased to 17.190.28 g/l (p>0.012 log CFU/ml) and EPS production (18.710.19 g/l) were achieved when 15 g/l of glucose was employed as the carbon source.