A media design program for lactic acid production coupled with extraction by electrodialysis

The aim of this study was to investigate industrial media for lactic acid fermentation to reduce the cost of nitrogen sources. Corn steep liquor (CSL) was successfully used at 5% (v/v) in batch fermentations. Use of soluble CSL improved the productivity approximately 20% with an advantage of clearer fermentation broth. Yeast extract (YE)-complemented CSL media further increased the productivity. It was found that 3.1 g L-1 yeast extract and 5% CSL could be an effective substitute for 15 g L-1 yeast extract in 10% glucose medium. Spent brewery yeast was also used as a sole nitrogen source equivalent to 5% CSL. Lactic acid was recovered by electrodialysis from the cell free broth. Depleted cell free broth supplemented with 5 g L-1 of yeast extract performed reasonably in batch cultures. Reuse of the fermentation broth may reduce the cost of raw materials as well as minimize the fermentation wastes. (c) 2005 Elsevier Ltd. All rights reserved.