Batch and repeated batch production of l (+)-lactic acid by Enterococcus faecalis RKY1 using wood hydrolyzate and corn steep liquor
2006
Wee, Y.J. | Yun, J.S. | Kim D. | Ryu, H.W.
Lactic acid production was investigated for batch and repeated batch cultures of Enterococcus faecalis RKY1, using wood hydrolyzate and corn steep liquor. When wood hydrolyzate (equivalent to 50 g l-1 glucose) supplemented with 15-60 g l-1 corn steep liquor was used as a raw material for fermentation, up to 48.6 g l-1 of lactic acid was produced with, volumetric productivities ranging between 0.8 and 1.4 g l-1 h-1. When a medium containing wood hydrolyzate and 15 g l-1 corn steep liquor was supplemented with 1.5 g l-1 yeast extract, we observed 1.9-fold and 1.6-fold increases in lactic acid productivity and cell growth, respectively. In this case, the nitrogen source cost for producing 1 kg lactic acid can be reduced to 23% of that for fermentation from wood hydrolyzate using 15 g l-1 yeast extract as a single nitrogen source. In addition, lactic acid productivity could be maximized by conducting a cell-recycle repeated batch culture of E. faecalis RKY1. The maximum productivity for this process was determined to be 4.0 g l-1 h-1.
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