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.
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ABSTRACT: Lactic acid bacteria (LAB) have long been used in industrial applications mainly as starters for food fermentation or as biocontrol agents or as probiotics. However, LAB possess several characteristics that render them among the most promising candidates for use in future biorefineries in converting plant-derived biomass – either from dedicated crops or from municipal/industrial solid wastes – into biofuels and high value-added products. Lactic acid, their main fermentation product, is an attractive building block extensively used by the chemical industry, owing to the potential for production of polylactides as biodegradable and biocompatible plastic alternative to polymers derived from petrochemicals. LA is but one of many high-value compounds which can be produced by LAB fermentation, which also include biofuels such as ethanol and butanol, biodegradable plastic polymers, exopolysaccharides, antimicrobial agents, health-promoting substances and nutraceuticals. Furthermore, several LAB strains have ascertained probiotic properties, and their biomass can be considered a high-value product. The present contribution aims to provide an extensive overview of the main industrial applications of LAB and future perspectives concerning their utilization in biorefineries. Strategies will be described in detail for developing LAB strains with broader substrate metabolic capacity for fermentation of cheaper biomass.Biotechnology Advances 08/2014; 32(7). DOI:10.1016/j.biotechadv.2014.07.005 · 8.91 Impact Factor
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ABSTRACT: Sugarcane bagasses are one of the most extensively used agricultural residues. Using acid hydrolysis and fermentation, conversion of sugarcane bagasses to lactic acid was technically and economically feasible. This research was concerned with the solubility of lignin in ammonium hydroxide, acid hydrolysis and lactic acid fermentation by Lactococcus lactis, Lactobacillus delbrueckii, Lactobacillus plantarum, and Lactobacillus casei. The lignin extraction results for different ammonium hydroxide concentrations showed that 10 % (v/v) NH4OH was favorable to lignin dissolution. Acid hydrolysis can be enhanced with increasing acid concentration and reaction temperature. The optimum glucose and xylose concentrations occurred at 121 ○C for 1 hour hydrolysis time in 10% sulphuric acid solution were 32 and 11 g/l, respectively. In order to investigate the significance of medium composition on lactic acid production, experiments were undertaken whereby a culture of Lactococcus lactis was grown under various glucose, peptone, yeast extract and xylose concentrations. The optimum medium was composed of 5 g/l glucose, 2.5 g/l xylose, 10 g/l peptone and 5 g/l yeast extract. Lactococcus lactis represents the most efficient for lactic acid production amongst those considered. The lactic acid fermentation by Lactococcus lactis after 72 hours gave the highest yield of 1.4 (g lactic acid per g reducing sugar).World Journal of Engineering and Technology 01/2012; 66:173-178.
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ABSTRACT: The present study was conducted to investigate the influence of initial sucrose concentration, pH and aeration rate on biomass and inulinase production by Kluyveromyces marxianus var. bulgaricus in a stirred batch reactor. Maximum inulinase activity (15.29 UmL-1) was obtained at a sucrose concentration of 10 g L-1, pH 5.0 and aeration rate of 1 vvm. The 20 g L-1 sucrose concentration was suitable for cell growth; however, enzymatic activity at this concentration was inhibited due to catabolic repression. The increase in aeration rate caused a reduction in enzyme activity with no relevant biomass increase.Brazilian Archives of Biology and Technology 06/2010; 53(3):701-707. DOI:10.1590/S1516-89132010000300027 · 0.45 Impact Factor