Lactic acid production through cell-recycle repeated-batch bioreactor.
The effect of various nitrogen sources on cell growth and lactic acid production was investigated. The most effective nitrogen source was yeast extract; more yeast extract gave higher cell growth and lactic acid productivity. Yeast extract dosage and cell growth were proportional up to a yeast extract concentration of 30 g/L, and lactic acid productivity was linearly correlated up to a yeast extract dosage of 25 g/L. However, increasing the yeast extract content raises the total production cost of lactic acid. Therefore, we attempted to find the optimum yeast extract dosage for a repeated-batch operation with cell recycling. The results show that when using Enterococcus faecalis RKY1 only 26% of the yeast extract dosage for a conventional batch fermentation was sufficient to produce the same amount of lactic acid, whereas the lactic acid concentration in the product stream (92-94 g/L) and lactic acid productivity (6.03-6.20 g/[L x h]) were similar to those of a batch operation. Furthermore, long-term stability was established.
Faculty of Applied Chemical Engineering, Institute of Bioindustrial Technology, Chonnam National University, Gwangju 500-757, Korea.
Hurok
H
Oh
Young-Jung
YJ
Wee
Jong-Sun
JS
Yun
Hwa-Won
HW
Ryu
D019149:Bioreactors; D001709:Biotechnology / Q000295:instrumentation / Q000379:methods; D002455:Cell Division; D003247:Conservation of Natural Resources / Q000379:methods; D004867:Equipment Design; D005285:Fermentation; D005947:Glucose / Q000378:metabolism; D019344:Lactic Acid / Q000302:isolation & purification* / Q000378:metabolism; D015003:Yeasts / Q000254:growth & development
D019344:Lactic Acid; D005947:Glucose