Abstract: S-adenosylmethionine (SAM) is a physiological active substance involved in a range of biochemical reactions of all living organisms, the intracellular level of ATP is one of the factors that restrict the synthesis of SAM in yeast. This study cloned and overexpressed the Adk1 gene in Saccharomyces cerevisiae CGMCC 2842. The results showed that the overexpression of Adk1 gene increased  intracellular  ATP  level  by 47.1% and SAM accumulation by 47%. When 6 g·L-1 sodium citrate feeding was investigated at 16 h after inoculation, the level of isocitrate dehydrogenase gene mRNA and IDH activity efficiently increased, which improved the intracellular level of ATP by 39.4% at 24 h. Compared with CK, the SAM accumulation and biomass yield were improved by 79% and 78.8%, respectively. Above results indicated the increase of intracellular ATP levels promoted the transformation of Met into SAM, which provided a strong theoretical basis for the regulation of ATP metabolism and the improvement of SAM synthesis.

Key words: yeast, S-adenosylmethionine, ATP metabolism, Adk1 overexpression, sodium citrate supplement

摘要： S-腺苷甲硫氨酸（SAM）是参与生物体众多生化反应的生理活性物质，酵母胞内ATP的水平是限制胞内SAM合成的因素之一。在酿酒酵母CGMCC 2842中克隆并过表达Adk1基因，发现Adk1基因的过表达使得酵母胞内ATP水平提高47.1%，SAM积累量提高47%；发酵16 h向发酵液中添加6 g·L-1柠檬酸钠，异柠檬酸脱氢酶基因mRNA水平和IDH酶活显著提高，在发酵24 h时胞内ATP水平提高39.4%，与对照相比，SAM积累量和对生物量得率分别提高79%和78.8%，表明胞内ATP水平的提高促进Met转化为SAM，这为ATP代谢调控而改善SAM合成提供有力的理论依据。

关键词: 酵母, S-腺苷甲硫氨酸, ATP代谢, Adk1过表达, 柠檬酸钠补料