RESUMO
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°C, 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.