A novel one-step microbial transformation of betulin to betulinic acid catalysed by Cunninghamella blakesleeana

► Cunninghamella blakesleeana can be used to convert betulin into betulinic acid. ► The transformation of betulin by cultured cell was proposed. ► We report the optimised bioconversion conditions for betulinic acid by cultured cells. Betulinic acid and its derivatives are potential bioactive compounds present in nature. This study investigated the biotransformation of betulin to betulinic acid by Cunninghamella blakesleeana cells. LC–MS analysis demonstrated that betulin could be transformed into at least five products from cultured C. blakesleeana cells, among which betulinic acid was the most important. The presented method provides an attractive alternative approach to chemical synthesis, because is less time-consuming and more environmentally friendly. C. blakesleeana can transform betulin into potent derivatives with high pharmacological activities.