Enhanced production of L-serine in Escherichia coli by fermentation process optimization and transcriptome sequencing

In this study, the performance of Escherichia coli fermentation for L-serine production was improved by fermentation process optimization and transcriptomic analysis. The induction point, induction temperature, dissolved oxygen level and nitrogen source addition in the fed batch fermentation were studied separately to determine the optimal fermentation process. And transcriptome sequencing was applied to the fermentation process to reveal the key metabolic pathways affecting L-serine production. The results showed that the highest titer of L-serine reached 45.66 g/L with a yield of 0.39 g/g when the induction point, induction temperature, dissolved oxygen level and nitrogen source addition were OD600 = 15, 39 ℃, 40% and 10%, respectively. Transcriptome sequencing results showed that cysteine and methionine metabolism were closely related to L-serine synthesis, and the addition of L-cysteine to the medium promoted cell growth and sustained accumulation of L-serine.