Fig. 7.

Fermentation process optimization to improve (2S)-sakuranetin production.

(A) The accumulation of (2S)-sakuranetin when rpoS and secB were co-expressed with methylation-strengthening genes. (B) Effects of different (2S)-naringenin addition time on the production of (2S)-sakuranetin. The final concentration of (2S)-naringenin was 700 mg/L. (C) Effects of different Mg²⁺

levels on the production of (2S)-sakuranetin. (2S)-Naringenin was first added after IPTG was added for 3 h, and different concentrations of Mg²⁺

were added at the same time. The final concentration of (2S)-naringenin was 700 mg/L. (D) Strain NS34 was fermented in a 5-L bioreactor, and (2S)-naringenin was added in batches to a final concentration of 4 g/L.