Brewer's yeast autolysate utilization for lactic acid production in batch fermentor

Abstract

Lactic acid production in this study was carried out in a batch fermentor using lactic acid bacteria Lactobacillus salivarius subsp. salivarius ATCC 11741.Glucose from cassava starch hydrolysate (CSH) and brewer’s yeast autolysate (BYA) were used as carbon and nitrogen source for the producing lactic acid. The effect of pH, commercial grade glucose (CG) concentration, glucose from cassava starch hydrolysate (CSH) concentration, yeast extract concentration (YE) and brewer’s yeast autolysate (BYA) concentration on cell growth and lactic acid production were investigated. In addition, the comparison between CG and CSH, YE and BYA were studied. Moreover, we studied the effect of the bitterness of BYA on lactic acid production. We found that the CG and YE had more good effect for lactic acid production than CSH and BYA. Whereas, a higher lactic acid yields were investigated from using CSH and BYA as a carbon and nitrogen source, so it recommends that the blending of CG with CSH and YE with BYA for lactic acid production is the one choice for reduce the cost of carbon and nitrogen source. The optimum pH, commercial grade glucose (CG) concentration, cassava starch hydrolysate (CSH) concentration and brewer’s yeast autolysate (BYA) concentration for lactic acid production were found to be 5.5, 70 g/l, 70 g/l and 48 ml/l, respectively. Moreover, the result shows that the bitterness of BYA didn’t effect the lactic acid production but the debittering of the bitterness was good for cell growth.