酵母菌利用糖蜜发酵产麦角甾醇的工艺条件优化

Improving ergosterol production from molasses by Saccharomyces cerevisiae

摘要:

麦角甾醇是由酵母菌产生的具有重要经济价值的代谢产物。为了提高酵母菌利用糖蜜发酵生产麦角甾醇的产量，通过响应面分析法优化了发酵培养基配方，并在5 L发酵罐对发酵过程pH控制和底物流加补料方式进行了优化。结果表明，利用优化后的发酵培养基，即糖蜜总糖40 g/L，KH2PO4 1 g/L，K2HPO4 1.86 g/L，CuSO4·5H2O 17.5 mg/L，FeSO4·7H2O 13.9 mg/L，MgSO4·5H2O 12.3 mg/L，玉米浆10 mL/L，麦角甾醇产量比优化前提高了29.5%；利用恒定pH控制策略，在5 L发酵罐进行分批发酵，使麦角甾醇产量提高了62.1%；进一步采用底物流加补料策略，使麦角甾醇产量达到1 953.85 mg/L，是分批发酵的3.2倍，而且麦角甾醇产率比分批发酵提高了42.7%。为酵母菌发酵糖蜜产麦角甾醇的产业化应用奠定了基础。

Abstract:

Ergosterol is an economically important metabolite produced by yeast. To improve the production of ergosterol by Saccharomyces cerevisiae YEH56 (pHXA42) from molasses, a cheap and regenerative material, different strategies were applied. First, Plackett-Burman design and central composite design were applied to screen the significant factors in fermentation medium using ergosterol yield (g/L) as the response value. Ergosterol yield reached 371.56 mg/L by using the optimal fermentation medium in shake-flask culture (total sugar in molasses 40 g/L, KH2PO4 1 g/L, K2HPO4 1.86 g/L, CuSO4·5H2O 17.5 mg/L, FeSO4·7H2O 13.9 mg/L，MgSO4·5H2O 12.3 mg/L, corn steep liquor 10 mL/L), which was increased by 29.5% compared with the initial culture. Second, ergosterol yield was increased by 62.1% using a pH-control strategy in a 5-L bioreactor. Third, ergosterol production was improved further by using molasses feeding strategy. After 38 h fermentation, ergosterol yield reached 1 953.85 mg/L, which was 3.2 times of that in batch fermentation. Meanwhile, ergosterol production rate was increased by 42.7% compared with that in the batch culture.