Content: The epothilones, macrolide agents with the similar anticancer mechanism to paclitaxel (Taxol), were originally isolated from culture extracts ofSorangium cellulosum strain So ce90 in 1987.Since then a large number of S.cellulosum strains have been screened, among which only 2％ were capable of producing epothilones.Up to date, the So0157-2 and So ce90 strains are two comprehensively studied epothilone producers.