Efficient biosynthesis of (2S)-pinocembrin from d-glucose by integrating engineering central metabolic pathways with a pH-shift control strategy. (October 2016) - Wu, Junjun
Graphical abstract: Highlights: An efficient de novo one-step (2S)-pinocembrin production process was established. CRISPR interference system was employed to improve malonyl-CoA concentration. Effect of culture pH on operation of overall synthetic pathway was investigated. A two-stage pH control strategy was used to effectively operate overall pathway. Abstract: Microbial fermentations promise to revolutionize the conventional extraction of (2S)-pinocembrin from natural plant sources. Previously an Escherichia coli fermentation system was developed for one-step (2S)-pinocembrin production. However, this fermentation platform need supplementation of expensive malonyl-CoA precursor malonate and requires morpholinopropane sulfonate to provide buffering capacity. Here, a clustered regularly interspaced short palindromic repeats interference was constructed to efficiently channel carbon flux toward malonyl-CoA. By exploring the effects of different culture pH on microbial fermentation, it was found that high pH values favored upstream pathway catalysis, while low pH values favored downstream pathway catalysis. Based on this theory, a two-stage pH control strategy was proposed. The pH was controlled at 7.0 during 0–10 h, and was shifted to 6.5 after 10 h. Finally, the (2S)-pinocembrin titers increased to 525.8 mg/L. These results were attained in minimal medium without additional precursor supplementation, thus offering opportunities for industrial scale low-cost production of flavonoids.