Abstract
The filamentous fungi Aspergillus niger, Mucor racemosus, Alternaria alternata and Rhizopus oryzae and the bacterium Bacillus stearothermophilus were isolated as natural contaminants of Thailand maize. Aspergillus flavus alone or in association with each of these microorganisms was inoculated onto irradiation-sterilized maize seeds and incubated aseptically in microporous bags at 30 °C and 0·95 aw and analyzed for total aflatoxins at days 5 and 10. After 5 d all combinations yielded less total aflatoxins than the single culture of A. flavus. Continued cultivation for 10 d resulted in an approximately 20% decrease in aflatoxin levels in the single A. flavus control with similar decreases in dual culture with the other microorganisms except Rhizopus oryzae and A. niger with levels of 27 and 32% respectively. Incubation at 40° after an initial 5 d incubation at 30° gave increased degradation of aflatoxin by the single culture of A. flavus (40%) with similar results with dual cultivation with Mucor racemosus, and Alternaria alternata. However, dual cultivation with A. niger, Rhizopus oryzae and Bacillus stearothermophilus resulted respectively in 80, 70 and 87% degradation of total aflatoxins; subsequent inoculation of these three microorganisms onto killed (autoclaved) 5-d A. flavus/maize cultures demonstrated the ability of each microorganism to degrade aflatoxin.
Published Version
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