为增加酵母抽提物鲜度以更好地满足其在食品领域的需求,在10 L发酵罐水平研究了柠檬酸钠-糖蜜补料策略对酿酒酵母J-5生长及胞内谷氨酸合成的影响。糖蜜流加补料发酵中存在显著的溢流代谢,乙醇浓度(10 h)高达 22 g/L,干重和胞内谷氨酸分别达到36.36 g/L(21 h)和2.28%(质量分数)(18 h)。而3~14 h采用50 mL/h的初始速度流加糖蜜(体积1.8 L,含72 g柠檬酸钠)和每2 h流速增加50 mL的策略,能有效地减少碳溢流代谢,乙醇质量浓度(10 h)仅为对照的54.5%。同时,显著提高了胞内谷氨酸合成效率,其峰值含量达到了3.7%(质量分数)(11 h),比优化前提高了62.3%。该文确定了柠檬酸钠浓度/峰值菌体干重为0.238±0.007的优化参数,为工业化放大实验提供了参数依据。
In order to enhance the freshness of yeast extract to better meet its needs in food industries, the effects of sodium citrate-molasses feeding strategy on the growth and intracellular glutamate synthesis in Saccharomyces cerevisiae J-5 were studied at a 10 L fermenter level. During molasses-fed fermentation, there was a significant overflow metabolism, and the ethanol concentration reached 22 g/L in 10 h. Besides, the dry weight and intracellular glutamate reached 36.36 g/L in 21 h and 2.28% in 18 h, respectively. Adding 1.8 L molasses that contained 72 g sodium citrate from 3 h to 14 h at an initial rate of 50 mL/h with an increasing flow rate of 50 mL every 2 h, the carbon overflow metabolism was effectively reduced. Moreover, the ethanol concentration in 10 h was only 54.5% of the control. Furthermore, the intracellular glutamate synthesis efficiency significantly improved, and the peak content reached 3.7% in 11 h, which was 62.3% higher than that of the control. In addition, the parameter of citrate content/the maximal cell dry weight under the optimized condition was 0.238±0.007, which provides a reference for industrial scale-up experiments.
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