海洋拟诺卡氏菌株HY-G转化大豆异黄酮苷的发酵条件的优化

目的：优化大豆异黄酮苷微生物转化的发酵条件。方法：利用本实验室筛选出的海洋拟诺卡氏菌株HY-G进行生物转化，采用单因素和正交试验，对发酵条件和培养基组成及条件进行优化。结果：筛选的最佳发酵工艺为在高氏一号基础培养基中加入1g/100mL蔗糖、0.03g/100mL硫酸铵和200mg/L诱导物的培养基进行培养，培养基装液量150mL/250mL，起始pH8.0，培养温度40℃，摇瓶转速120r/min，培养72h。优化后的酶活力分别达3621U/mL(对染料木素)和4862U/mL(对大豆苷元)。结论：经过优化，得出了较好的产酶发酵工艺，有利于进一步采用大规模发酵法转化大豆异黄酮苷元。

Optimization of Fermentation Conditions for Soybean Isoflavone Biotransformation by Marine Nocardiopsis sp. HY-G

Objective: Nocardiopsis sp. HY-G, a strain isolated from marine environment by our laboratory, has been found to produce large amounts of hydrolases that can transform soybean isoflavones (SI) into genistein and daidzein during fermentation. In this study, medium composition and fermentation conditions for decomposing SI by the strain were optimized. Methods: Single factor and orthogonal array design methods were combinedly used for the optimization of fermentation conditions and medium composition. Results: The optimal fermentation medium was Gausse No.1 medium fortified with 1 g/100 mL sucrose, 0.03 g/100 mL (NH4)2SO4, 200 mg/L SI and initial pH 8.0. Fermentation temperature of 40 ℃, rotation speed of 120 r/min and fermentation time of 72 h in a 250 mL shake flask with 150 mL of medium were found optimum for culturing the strain. The activity towards the substrate genistein of the resulting product was 3621 U/mL and the activity towards daidzin was 4862 U/mL. Conclusion: The optimum fermentation conditions obtained after optimization are true and reliable, which will be helpful for large scale biotransformation of SI.