目的 为提高短刺小克银汉霉对马钱子中马钱子碱与士的宁的转化率，构建高效的短刺小克银汉霉微生物转化体系。方法 根据菌种的生长代谢规律，采用单因素实验法，以马钱子碱硫酸盐和士的宁硝酸盐作为底物，以对底物的转化率作为指标，对可能的影响因素进行了考察。结果 获得了优化的转化工艺，即接种量为4%、发酵时间为2.5 d、底物质量浓度为20 mg/L、转化时间为3 d、培养温度为28 ℃、培养基初始pH值为6.5、摇床转速为150 r/min。在此工艺条件下，2种底物的平均转化率分别达到了77.75%与77.10%。结论 短刺小克银汉霉对2种底物的平均转化率分别提高了约17%与22%，此微生物转化体系能够满足马钱子减毒存效研究的需要。

Objective To enhance the transformation rate of brucine and strychnine in Strychnos nux-vomica and establish a high efficient microbial transformation system by Cunninghamella blakesleeana. Methods Based on the growth and metabolic rule of C. blakesleeana, through single-factor experiments, by using brucine sulphate and strychnine nitrate as substrates and the transformation rate of each substrate as index, several influential factors were investigated. Results The optimal transformation condition was inoculation amount at 4%, fermentation time at 2.5 d, substrate concentration at 20 mg/L, transformation time at 3 d, culture temperature at 28 ℃, initial pH of medium at 6.5, and shaking speed at 150 r/min. Under the above condition, the average transformation rates of brucine sulphate and strychnine nitrate were approximate 77.75% and 77.10%, respectively. Conclusion The average transformation rates of brucine sulphate and strychnine nitrate are increased by about 17% and 22%, respectively by C. blakesleeana, and this microbial transformation system could meet the need of the study on “toxicity attenuation and efficacy reservation” of S. nux-vomica.

江苏省高校优势学科建设工程资助项目（ysxk-2010）；南京中医药大学青年自然科学基金资助项目（11XZR13）