Gao Song, Zhou Jingwen, Chen Jian
National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, Wuxi 214122, Jiangsu, China.
School of Biotechnology, Jiangnan University, Wuxi 214122, Jiangsu, China.
Sheng Wu Gong Cheng Xue Bao. 2020 Dec 25;36(12):2838-2849. doi: 10.13345/j.cjb.200178.
(2S)-taxifolin is an important flavonoid that has anti-inflammatory and anti-oxidation effects. It is widely used in pharmaceutical and nutraceutical industries. Flavone 3-hydroxylase (F3H) can catalyze the synthesis of (2S)-taxifolin and other 3-hydroxylated flavonoids from (2S)-eriodictyol. Due to the low catalytic efficiency of F3H, the titer of many 3-hydroxyflavones, such as taxifolin, synthesized by microbial method is relatively low. In this study, a SmF3H was identified from the transcriptome of Silybum marianum (L.) Gaertn. The results of fermentation showed that SmF3H can catalyze the flavone 3-hydroxylation reaction, and its catalytic efficiency was significantly higher than that of commonly used SlF3H from Solanum lycopersicum. Six promoters with different transcription strength were selected to optimize the synthesis pathway from the flavonoid precursor (2S)-naringenin to (2S)-taxifolin. The results showed that the highest titer of (2S)-taxifolin (695.90 mg/L in shake flask) could be obtained when the P(GAL7) promoter was used to control the expression of SmF3H. The titer of (2S)-taxifolin was further improved to 3.54 g/L in a 5-L fermenter, which is the highest titer according to current available literatures.
（2S）-紫杉叶素是一种重要的黄酮类化合物，具有抗炎和抗氧化作用。它广泛应用于制药和营养保健品行业。黄酮3-羟化酶（F3H）可以催化从（2S）-圣草酚合成（2S）-紫杉叶素和其他3-羟基化黄酮类化合物。由于F3H的催化效率较低，通过微生物方法合成的许多3-羟基黄酮（如紫杉叶素）的产量相对较低。在本研究中，从水飞蓟的转录组中鉴定出一种SmF3H。发酵结果表明，SmF3H可以催化黄酮3-羟基化反应，其催化效率显著高于常用的来自番茄的SlF3H。选择六个具有不同转录强度的启动子来优化从黄酮类前体（2S）-柚皮素到（2S）-紫杉叶素的合成途径。结果表明，当使用P（GAL7）启动子控制SmF3H的表达时，可以获得最高产量的（2S）-紫杉叶素（摇瓶中为695.90 mg/L）。在5-L发酵罐中，（2S）-紫杉叶素的产量进一步提高到3.54 g/L，这是根据目前现有文献报道的最高产量。
