Aflatoxin B1and G1Production in Developing Zea mays Kernels from Mixed Inocula of Aspergillus flavus and A. parasiticus

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Abstract
Yields of aflatoxin B1 for various fungal conidial proportions used as inocula (0/100% A. flavus only, 25/75, 50/50, 75/25 and 100/0% A. parasiticus only) were relatively constant for all inoculation treatments. But the yields of aflatoxin G1, produced only by A. parasiticus in the mixed inocula showed marked significant decreases from that produced by A. parasiticus alone. Ratios calculated from the aflatoxin G1 and B1 produced, remained relatively constant for each inoculum regardless of the inoculation treatment, but G1/B1 ratios for each treatment decreased significantly as the proportion of A. flavus conidia in the inocula increased. Production of aflatoxin G1 and B1 was significantly greater in the thin- than in the thick-pericarp hybrid. The highest amounts of aflatoxin G1 and B1 were observed when the husks of the ears were pulled back and the kernels either razor- or pinboard-injured before inoculation. The lowest amounts were observed for the widely-used hypodermic-syringe method. A. parasiticus in mixtures is apparently significantly limited from developing fully by A. flavus in competing for the same corn substrate. This may help explain why A. flavus routinely is found present in naturally aflatoxin-contaminated corn and A. parasiticus only rarely.