重组大肠杆菌发酵生产谷胱甘肽的氨基酸添加策略优化

摘要

对表达双功能谷胱甘肽合成酶的重组大肠杆菌发酵生产谷胱甘肽（Glutathione，GSH）进行氨基酸添加策略优化，结果表明：基本培养基中未添加氨基酸时GSH产量为0.81 g/L；诱导2 h后添加17 mmol/L半胱氨酸GSH产量为1.16 g/L，比不加氨基酸提高43%；添加17 mmol/L的3种前体氨基酸，GSH产量达到3.86 g/L，比只添加半胱氨酸提高2.33倍；进一步提高3种氨基酸添加量至25 mmol/L，GSH产量可达4.64 g/L，比不添加氨基酸提高4.73倍，总生产强度高达317.8 mg/（L·h），半胱氨酸转化为谷胱甘肽达到0.60 mol/mol；考察氨基酸添加模式发现一次性添加25 mmol/L氨基酸较恒速流加模式生产速率提高了29.8%。后续在50 L罐放大生产GSH，产量为4.31 g/L，总生产强度达到310.1 mg/（L·h），为工业化放大生产GSH奠定了基础。%The condition of amino acids was optimized in the production of glutathione(GSH)by recombinant Escherichia coli expressing bifunctional glutathione synthetase. Only 0.81 g/L of GSH was produced without adding any amino acid, whereas 1.16 g/L of GSH was formed when 17 mmol/L of cysteine was fed into the medium after 2 h induction, increasing 43%compared to no amino acid added. With the feeding 17 mmol/L of 3 precusor amino acids, the production was improved significantly and achieved at 3.86 g/L, which was 2.33 times of single cysteine addition. By increasing the amount of 3 amino acids to 25 mmol/L, GSH was 4.64 g/L, 4.73 times as no amino acid added, and the overall productivity was 317.8 mg/(L·h), the conversion rate of cysteine to glutathione was 0.60 mol/mol. While concerning the addition mode, the production rate of GSH was 3.09 g/(L·h)when 25 mmol/L of amino acids was once added to the fermenter, only 2.38 g/(L·h) when 25 mmol/L of amino acids added at constant speed and continuously, so the productivity increased 29.8%by adding once. The process was successfully scaled up in the 50 L fermenter and 4.31 g/L of GSH was produced with an overall productivity of 310.1 mg/(L·h), which laid a foundation for the industrial production of GSH.