In the present study, the ability of Escherichia coli to produce L-serine by fermentation using glycerol and glucose was investigated. The results showed that the maximum accumulation of L-serine in glycerol and glucose medium was 634.37 mg/L and 459.27 mg/L, respectively. Transcriptome sequencing was then applied to explore the reasons for this difference, and showed: (1) A total of 2041 differentially expressed genes (DEGs) were screened, and these DEGs were mainly concentrated in biosynthesis of amino acids and histidine metabolism；(2) In the biosynthesis of amino acids, the key genes (e.g., tdcG、ilvA and tdcB) involved in the degradation of L-serine to pyruvate were significantly down-regulated; (3) The key genes (e.g., ilvB、ilvN and ilvM etc) involved in the degradation of pyruvate to branched-chain amino acids were significantly down-regulated; (4) Many up-regulated genes appeared in the glycine anabolic pathway, which may provide a large number of one-carbon units for the growth of E. coli.; and (5) Transcription levels of regulatory genes in histidine metabolism were down-regulated, which may reduce energy consumption. In summary, the present study provides insight at the genetic level into the construction of high-yielding strains for the efficient use of glycerol for L-serine synthesis.

在本研究中，研究了大肠杆菌使用甘油和葡萄糖发酵生产L-丝氨酸的能力。结果表明，L-丝氨酸在甘油和葡萄糖培养基中的最大积累分别为634.37 mg/L和459.27 mg/L。随后应用转录组测序探究造成这种差异的原因，结果表明：（1）共筛选出2041个差异表达基因（DEGs），这些DEGs主要集中在氨基酸生物合成和组氨酸代谢方面；（2）在氨基酸的生物合成中，参与L降解的关键基因（如tdcG、ilvA和tdcB ）-丝氨酸到丙酮酸显着下调；(3)参与丙酮酸降解为支链氨基酸的关键基因(如ilvB、ilvN和ilvM等)显着下调；(4)甘氨酸合成代谢途径中出现许多上调基因，可能为大肠杆菌的生长提供大量的单碳单元；(5) 组氨酸代谢调控基因的转录水平下调，可能降低能量消耗。总之，本研究提供了在遗传水平上构建高产菌株以有效利用甘油合成L-丝氨酸的见解。