The microorganism used in this study was M. purpureus NRRL1992. Stock cultures were maintained on Sabouraud dextrose agar plates and subcultured periodically. Cultures reactivated by transferring onto fresh Sabouraud plates and cultured at 30 1C for 8–12 days were used for inoculum preparation. The submerged culture media contained the carbon and nitrogen sources (as specified below) and in g/l: K2HPO4 (5.0), KH2PO4 (5.0), MgSO4 7H2O (0.01), CaCl2 (0.01) and ZnSO4 7H2O (0.01). The initial pH of the medium was adjusted to 6.0. Erlenmeyer flasks (125ml)
containing 25ml of medium were inoculated with 250 mlof a mycelium/spores suspension (in a 0.85% NaCl sterile solution) with an O.D.620 of approximately 0.4. The flasks were incubated at 2573 1C for 9 days in a rotatory shaker at 100 rpm. The concentration of extracellular red pigment was estimated by measuring the absorbance of filtrates at 500 nm, taking the dilution factor into consideration.