为了提高富硒产朊假丝酵母的性能，本文在摇瓶培养和分批培养的基础上，考察了不同pH控制方式对流加培养条件下富硒产朊假丝酵母细胞生长、谷胱甘肽（GSH）合成和有机硒转化的影响，结果发现：在12 h将pH从3.5切换至5.5（pH 3.5→5.5）的两阶段pH控制方式最有利于富硒产朊假丝酵母胞内GSH和有机硒含量的提高。在pH 3.5→5.5条件下，富硒产朊假丝酵母胞内GSH含量、有机硒含量和有机硒转化率分别达到最大值13.09 mg/g、1.88 mg/g和94.69%。通过对酵母胞内GSH合成关键酶活性、氧化还原酶活性和能量代谢物质ATP水平进行测定，发现pH 3.5→5.5两阶段pH控制方式提高了富硒酵母胞内过氧化氢酶活性，降低了丙二醛含量，为酵母进行有机硒富集与转化以及GSH合成与积累提供了合适的氧化还原环境，并最终提高了富硒酵母的性能。

Effects of different pH control modes on yeast cell growth, glutathione biosynthesis and organic selenium (Se) transformation during fed-batch culture of Se-enriched Candida utilis were investigated. Based on the results derived from both flask culture and batch culture, the fed-batch culture was carried out to improve the performance of Se-enriched C. utilis. A two-stage pH control strategy of shifting pH from 3.5 to 5.5 at 12 h (pH 3.5→5.5) was found to be the optimum condition for the increase in intracellular GSH and organic Se contents of Se-enriched C. utilis. The maximal intracellular glutathione, organic selenium content and organic selenium bioconversion rate of 13.09 mg/g, 1.88 mg/g and 94.69% were achieved, respectively, under pH 3.5→5.5. According to the assay of key enzyme activity involved in glutathione biosynthesis, the measurement of intracellular oxidoreductases, and the determination of energy metabolism substance ATP, the two-stage pH control strategy of pH 3.5→5.5 was found to favor the increase in catalase activity and the decrease in malondialdehyde content of Se-enriched C. utilis. Results indicated that pH 3.5→5.5 provided appropriate intracellular redox environment for selenium assimilation and transformation, as well as glutathione biosynthesis and accumulation, all of which ultimately improved the performance of Se-enriched yeast.

国家自然科学基金资助项目（21506136）；苏州市应用基础研究计划项目（SNG201606）