Efficient Biosynthesis of (2)-Eriodictyol from (2)-Naringenin in through a Combination of Promoter Adjustment and Directed Evolution.

The compound (2)-eriodictyol is an important flavonoid that can be derived from (2)-naringenin through flavonoid 3'-hydroxylase (F3'H) catalyzation. F3'H is a cytochrome P450 enzyme that requires a cytochrome P450 reductase (CPR) to function. However, P450s have limited applications in industrial scale biosynthesis, owing to their low activity. Here, an efficient F3'H and a matched CPR were identified from . To improve the efficiency of F3'H, we established a high-throughput detection method for (2)-eriodictyol, in which the promoter combination of F3'H and CPR were optimized in . The results revealed that F3'H/CPR should be expressed by using promoters with similar and strong expression levels. Furthermore, directed evolution was applied to further improve the efficiency of F3'H/CPR. With the optimized promoter and mutated combinations F3'H/CPR, the (2)-eriodictyol titer was improved to 3.3 g/L, the highest titer in currently available reports. These results indicated that is an ideal platform for functional expression of flavonoid related P450 enzymes.