对酿酒酵母工程菌Saccharomyces cerevisiae mls1△acs2-MetK在20 L发酵罐中合成腺苷甲硫氨酸(S-adenosyl-L-methionine,SAM)的补料分批培养工艺进行优化,增加糖蜜的流加时间,提高溶解氧水平;在此基础上,测定发酵过程中前体甲硫氨酸的消耗曲线,在发酵后期流加前体甲硫氨酸以提高SAM产量.结果表明,在32 ～ 72 h流加糖蜜发酵,最终SAM产量和生物量分别达到6.16 g/L和20.83 g/L.将溶解氧水平提高至30％,发酵136 h,最终SAM产量和生物量分别达到11.40 g/L和25.24 g/L.在此基础上,从96 h开始流加甲硫氨酸至发酵结束,最终SAM产量和生物量分别达到15.23 g/L和28.81 g/L.与未优化的工艺相比,SAM产量提高了147.24％.通过流加糖蜜、甲硫氨酸,提高溶解氧,可以有效提高酿酒酵母在20 L发酵罐中的SAM产量和生物量;该工艺在工业化生产中具有潜在的应用价值.“,”S-adenosyl-L-methionine (SAM) is a kind of very important metabolic product with various physiological activities.This study aimed to optimize the fed-batch fermentation process in 20-L fermenter,and to improve the SAM production with the engineered Saccharomyces cerevisiae,in order to satisfy the industrial and medical demand of SAM.In this study,the fed-batch fermentation of the engineered Saccharomyces cerevisiae was conducted in 20-L fermenter.The strategies of molasses feeding,dissolved oxygen regulation and methionine (Met) feeding were optimized to enhance the SAM accumulation in 20-L fermenter.Meanwhile,the concentrations of dry cell weight,reducing sugar and SAM were determined during the fermentation process.The obtained data revealed that,after molasses feeding from 32 h to 72 h,the final SAM production and dry cell wet (DCW) reached 6.16 g/L and 20.83 g/L at 136 h in 20-L fermenter.On this basis,after improving the dissolved oxygen to 30％,the final SAM production and DCW in the fermentation broth reached 11.40 g/L and 25.24 g/L after 136 h fermentation.Next,the Met concentration during the fermentation process in fermentation broth was determined by high-performance liquid chromatography (HPLC) method.The Met consumption curve in 136 h fermentation process revealed that the Met concentration in the fermentation broth was lower than 0.3 g/L after 96 h.Then the Met feeding strategy was operated in the fed-batch fermentation.Subsequently,with the molasses feeding,30％ dissolved oxygen and Met feeding,the SAM production and DCW reached 15.23 g/L and 28.81 g/L after 136 h fermentation.Above all,the SAM production under optimized fermentation condition in 20-L fermenter was improved by 147.24％,compared wtih the initial fermentation condition.The SAM production and DCW were obviously improved after molasses feeding,dissolved oxygen regulation and Met feeding,and finally reached 15.23 g/L and 28.81 g/L,which might have potential to satisfy the industrial scale production of SAM in the future.