Promoter-Library-Based Pathway Optimization for Efficient (2S)-Naringenin Production from p-Coumaric Acid in Saccharomyces cerevisiae

Pathway optimization plays an important role in fine-tuning metabolic pathways. In most conditions, more than three genes are involved in the biosynthesis pathway of a specific target product. To improve the titer of products, rational regulation of a group of genes by a series of promoters with different strengths is essential. On the basis of a series of RNA-Seq data, a set of 66 native promoters was chosen to fine-tune gene expression in Saccharomyces cerevisiae. Promoter strength was characterized by measuring the fluorescence strength of the enhanced green fluorescent protein through fluorescence-activated cell sorting. The expressions of PTDH1, PPGK1, PINO1, PSED1, and PCCW12 were stronger than that of PTDH3, whereas those of another 15 promoters were stronger than that of PTEF1. Then, 30 promoters were chosen to optimize the biosynthesis pathway of (2S)-naringenin from p-coumaric acid. With a high-throughput screening method, the highest titer of (2S)-naringenin in a 5 L bioreactor reached 1.21 g/L from p-coumaric acid, which is the highest titer according to the currently available reports.