Simultaneous saccharification and L-(+)-lactic acid fermentation of protease-treated wheat bran using mixed culture of lactobacilli

Protease-treated wheat bran (20% w/v) of particle size less than 300 microm containing 65% (w/w) starch was used for the simultaneous saccharification and L-(+)-lactic acid fermentation by the mixed cultures of Lactobacillus casei and Lactobacillus delbrueckii. Maximum lactate yield after various process optimizations was 123 g l(-1) with a productivity of 2.3 g l(-1) h(-1) corresponding to a conversion of 0.95 g lactic acid per gram starch after 54 h at 37 degrees C. By using protease-treated wheat bran around tenfold decrease in supplementation of the costly medium component, like yeast extract, was achieved together with a considerable increase in the production level.