Isolation and identification of lactic acid bacteria from sourdough with high exopolysaccharide production ability

To isolate lactic acid bacteria having high exopolysaccharides (EPS) production ability, 50 strains were initially isolated from the sourdough. Twenty-one strains formed highly mucoid colonies on the sucrose agar medium, which are indicative of active EPS synthesis. DU-07, DU-10, DU-12, DU-19, and DU-21 produced 11.51±0.167, 13.09±0.193, 12.72±0.108, 11.61±0.284, and 13.32±0.094 g/L EPS, respectively, in MRS medium. The isolated strains, DU-10, DU-12, and DU-21, were identified as Enterococcus flavescens, Enterococcus faecium, and Lactobacillus amylovorus, respectively, by using API 50CHL kit and determining partial sequences of their 16S rDNA. Especially, L. amylovorus DU-21 showed the highest production of EPS, as well as the highest inhibitory activities against pathogenic (p<0.05). Interestingly, the L. amylovorus DU-21 seem to be endemic to sourdough fermentations, as they have not been isolated from other environments.