Influence of gamma rays and sodium chloride on aflatoxin production by Aspergillus flavus.

The rate of Aspergillus flavus growth and production of aflatoxin in yeast extract sucrose medium generally decreased as the concentrations of NaCI increased from 2 to 12%. Maximum production and accumulation of aflatoxin at 28°C occurred after 7 days in the presence of NaCI concentrations. The number of colony forming units of A. flavus after 1.0 or 2.0 kGy irradiation was lower than in the unirradiated controls and the mould was eliminated at 3.0 kGy. Aflatoxin B 1 decreased from the control level of 46 μg kg -1 to 10 μg kg -1 at an irradiation dose level of 2.0 kGy. Viable gamma irradiated conidia (2.0 kGy) of A. flavus showed increased sensitivity to NaCI concentrations, indicating γ-ray injury. The levels of aflatoxin produced by 2.0 kGy irradiated conidia of A. flavus decreased in the presence of 2, 4 or 6% NaCI, and the detoxification rate was 94.1, 100 and 100%, respectively, after 21 days of incubation at 28°C compared with the effect of γ-rays or sodium chloride alone.