The growing need of highly potent anticancer agents has stimulated the investigation of streptomycetes producing daunomycin-type anthracyclines. This review compares the features of production strains and their mutants and emphasizes the necessity of application of biochemical and biophysical analytical methods for better understanding these microorganisms and, above all, their further improving and practical usage.

Semisynthetic derivatives of daunomycinone with 7,9-isopropylacetal, 7-O-methyl, 7-O-(4-penten-2-yl), and 7-O-(2-hydroxyethyl) substituents were converted by Streptomyces peucetius var. caesius (an adriamycin-blocked mutant) into 7-deoxy-13-dihydrodaunomycinone, while daunomycinone was transformed into 13-dihydrodaunomycinone (predominantly) and 7-deoxy-13-dihydrodaunomycinone. S. coeruleorubidus mutants 24-74 (accumulating aclavinone derivatives instead of daunomycin and related compounds) and 96-85 (producing no anthracycline substances), and S. aureofaciens B-96 (a tetracycline-blocked mutant) transformed the above substrates into the corresponding 13-dihydro derivatives, with the exception of 7,9-isopropylacetal daunomycinone which remained intact. 7-O-Propyn-1-yl daunomycinone was not transformed by any of the strains used under the conditions.