Co-production of aflatoxins and cyclopiazonic acid in isolates of Aspergillus flavus.

The distribution of total aflatoxin (AFT) and cyclopiazonic acid (CPA) between conidia and mycelial matrix was studied in five isolates of Aspergillus flavus Link cultured on maize grain for 20 days at 30 degrees C. Total aflatoxin and CPA production differed between the isolates with Aspergillus flavus F2R4FP 1-5 producing the most AFT (conidia-0.245 microgram/g; mycelial matrix-83 micrograms/g) and CPA (conidia-0.091 microgram/g; mycelial matrix-37 micrograms/g). The production of AFT and CPA by this isolate was compared in liquid (malt-extract-yeast-extract-glucose) and solid substrates (yeast extract sucrose agar and maize) at 30 degrees C. The ratio of AFT:CPA in maize decreased from 16.6:1 to 1.6:1 between 7 and 21 days' incubation. In liquid culture and yeast extract sucrose agar, the ratios were reversed and ranged from 1:3 to 1:9 and 1:22 to 1:28, respectively, the greatest difference in both media occurring after 15 days.