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目的:以熊果酸为底物,用长柄链格孢菌AS3.2875对熊果酸进行生物转化,并对培养基和转化条件进行优化。方法:以熊果酸的消耗率和28-O-β-D-吡喃葡萄糖熊果酸酯苷的生成率为指标,考察不同起始pH,磷酸盐,不同种类金属离子,孢子浓度,底物加入量,温度,转速,培养时间对熊果酸在长柄链格孢菌培养液中转化的影响,得到长柄链格孢菌对熊果酸的最佳转化条件。结果:优化后的培养条件为初始pH 5.0,0.25 g.L-1MgSO4,1.0 g.L-1K2HPO4,0.083 g.L-1FeSO4,孢子浓度为4%,底物加入量0.3 g.L-1,转速140 r.min-1,28℃,培养3 d。结论:长柄链格孢菌转化熊果酸生成28-O-β-D-吡喃葡萄糖熊果酸酯苷的生成率稳定在5%左右。
OBJECTIVE: Using ursolic acid as substrate, the ursolic acid was biotransformed with Alternaria elongatus AS3.2875, and the medium and transformation conditions were optimized. Methods: According to the consumption rate of ursolic acid and the production rate of 28-O-β-D-glucopyranose ursoside, different initial pH, phosphate, different kinds of metal ions, spore concentration, The effects of amount, temperature, rotation speed and culture time on the transformation of ursolic acid in Alternaria longus were studied. The optimal transformation conditions for ursolic acid were obtained. Results: The optimized culture conditions were initial pH 5.0, 0.25 gL-1MgSO4, 1.0 gL-1K2HPO4 and 0.083 gL-1FeSO4. The spore concentration was 4%, the substrate concentration was 0.3 gL- 28 ℃, cultured for 3 d. CONCLUSION: The yield of 28-O-β-D-glucopyranose ursoside produced by Ursolic acid converting ursolic acid is about 5%.