NEW MATERIAL:An anticancer substance crucivin, having the following physicochemical properties, and obtained by cultivating a microorganism capable of producing the crucivin. (1) Polypeptide. (2) Melting point: Showing no specific value. (3) Specific rotatory power [α]D20=-112°(measured by using a 0.5% solution in M/15 phosphoric acid buffer solution of pH 7.2). (4) Solubility: Soluble in water; readily soluble in 0.2W5% aqueous solution of common salt, sulfate or phosphate (pH=6W8); insoluble in methanol, acetone, benzene, etc. (5) Positive to the biuret and Sakaguchi reactions. (6) Molecular weight:7,000(column gel filtration method).

USE: An anticancer agent.

PROCESS: A microorganism, e.g. Pseudomonas cruciviae IFO 12047, capable of producing crucivin is preferably cultivated at pH 6.8W7.0 and 30W32°C for 4W20 days by the stationary calture method. The resultant substance is then extracted and purified.