产腺苷甲硫氨酸酿酒酵母半胱氨酸补料工艺的研究

Study on Cysteine Addition in Fed-Batch Fermentation of S-Adenosylmethionine Production by Saccharomyces Cerevisiae

对酿酒酵母生物合成腺苷甲硫氨酸(S-adenosylmethionine,SAM)发酵过程进行工艺优化,研究了半胱氨酸添加量、半胱氨酸添加时间、碳源对菌体浓度和SAM产量的影响。结果表明,在10 L发酵罐中,发酵16 h时,补加半胱氨酸至浓度2 mmol/L,发酵36 h时菌体(DCW)和SAM浓度分别达到15.40 g/L和4.11 g/L;在此基础上,更换糖蜜为碳源,并在还原糖浓度低于5 g/L时,流加糖蜜,相当于还原糖的流加速率为0.8 g/L.h,发酵36 h时菌体浓度和SAM产量分别为15.50 g/L和5.02 g/L;经过发酵工艺优化,发酵液中SAM浓度提高了43.8%。

In order to improve the S-adenosylmethionine （SAM）yields, the fermentation process of SAM biosynthesis by Saccharomycescerevisiae CGMCC 2842 was optimized, adding different concentrations of cysteine as 0,2,4,6,8 mmol/L at 20 h , adding 2 mmol/L cysteine at different time as 0,12,16,20,24 h and different carbon sources of glucose, maltose, sucrose, and molasses on biomass concentration and production of SAM after 36 h fermentation in 250 mL flasks, then chose the best fermentation conditions in 10 L stirred. The results indicated that in 250 mL flasks, adding 2 mmol/L cysteine at 16 h and used molasses as carbon source ,the SAM productions was obviously higher than others. In 10 L stirred, using glucose as carbon source without cysteine addition, the dry cell weight （DCW） reached maximum of 15.4 g/L at 20 h,the SAM accumulation reached maximum of 3.48 g/L at 24 h. Then, also using glucose as carbon source but adding cysteine as 2 mmol/L at 16 h, the DCW nearly reached 15.4 g/L and the maximum concentration of SAM reached 4. 11 g/L in 36 h fermentation, using molasses as carbon source and adding cysteine as 2 mmol/L at 16 h,the maximum DCW decreased to 14. 2 g/L at 26 h,but the maximum concentration of SAM increased to 4. 90 g/L at 28 h. Accordingly, using molasses as carbon source and adding molasses when the concentration of reducing sugar was below 5 g/L which was equivalent to reducing sugar feeding as 0. 8 g/L. h in fed-batch, after 16 h then adding 2 mmol/L cysteine, the maximum DCW reached 15.50 g/L at 26 h and the concentration of SAM was improved to 5.02 g/L at 34 h in 36 h fermentation. After optimization of fermentation process, concentration of SAM in fermented liquid increased by 43.8% than using glucose as carbon source without addition of cysteine. In this study, both molasses as carbon source and cysteine addition were helpful to improve the SAM accumulation.