Utilization of sugar molasses for economical l(+)-lactic acid production by batch fermentation of Enterococcus faecalis
ABSTRACT Lactic acid production from sugar molasses by batch fermentation of Enterococcus faecalis RKY1 was investigated in order to reduce the manufacturing cost of lactic acid. When the fermentation was carried out at pH 7.0, 95.7 g/l of lactic acid was obtained with a yield of 94.9% and productivity of 4.0 g/l h. Lactic acid fermentation using molasses was significantly affected by yeast extract concentrations. The maximum lactic acid productivity was obtained to 5.3 g/l h at 20 g/l of yeast extract. The final lactic acid increased with the increase of molasses concentrations, whereas the lactic acid productivity decreased probably due to substrate inhibition. When the medium containing 15 g/l of yeast extract was used, the maximum lactic acid concentration (134.9 g/l) and the maximum productivity (4.3 g/l h) were obtained at molasses concentrations of 333 g/l (equivalent to 170 g/l of total sugar) and 130 g/l (equivalent to 68 g/l of total sugar), respectively. In addition, l(+)-lactic acid content of lactic acid produced from molasses was above 98% in all cases experimented in this study.
- [show abstract] [hide abstract]
ABSTRACT: Lactic acid production from cellulosic biomass by cellulase and Lactobacillus delbrueckii was studied in a fermenter-extractor employing a microporous hollow fiber membrane (MHF). This bioreactor system was operated under a fed-batch mode with continuous removal of lactic acid by anin situ extraction. A tertiary amine (Alamine 336) was used as an extractant for lactic acid. The extraction capacity of Alamine 336 is greatly enhanced by addition of alcohol. Long-chain alcohols serve well for this purpose since they are less toxic to micro-organism. Addition of kerosene, a diluent, was necessary to reduce the solvent viscosity. A solvent mixture of 20% Alamine 336, 40% oleyl alcohol, and 40% kerosene was found to be most effective in the extraction of lactic acid. Progressive change of pH from an initial value of 5.0 down to 4.3 has significantly improved the overall performance of the simultaneous saccharification and extractive fermentation over that of constant pH operation. The change of pH was applied to promote cell growth in the early phase, and extraction in the latter phase.Applied Biochemistry and Biotechnology 02/1997; 63-65:435-48. · 1.89 Impact Factor
- [show abstract] [hide abstract]
ABSTRACT: A process for the fermentative production of lactic acid from whole-wheat flour consisting of starch and bran containing nutrients is presented and an economical evaluation of the lactic acid production cost performed. Bottlenecks were identified and alternative processes were evaluated and compared. The costs of raw material, the sodium hydroxide in the fermentation step, and the conversion of lactate to lactic acid using electrodialysis were found to contribute considerably to the total production cost. Performing the fermentation step as a batchwise step was economically better than continuous fermentation. The lactic acid production cost can be reduced by lowering the pH and/or by recycling the sodium hydroxide produced by electrodialysis to the fermentor. Using higher wheat flour concentrations reduced the lactic acid production cost and numerical optimisation of the process, with respect to the wheat flour concentration, showed that the optimal concentration corresponded to 116 g glucose/l, which resulted in a production cost of 0.833 US$/kg product. A Monte Carlo simulation of the total production cost for this concentration when the investment and operational cost and the price of the raw material were varied showed that the probability that the production cost could be lower than 0.90 or 1.0 US$/kg was 61% or 91%, respectively.Bioresource Technology. 01/2000;
- Analytical Chemistry. 01/2002; 28(3):350-356.