Effects of Low Oxygen on the Growth of Aspergillus Flavus and Aflatoxin Production.

Mycotoxins, a known carcinogen, are contaminating corn kernels in West and Central Africa even when stored in PICS bags (Purdue Improved Crop Storage bags) which were designed to minimalize the effects of insect damage to stored grain and seed.  It was hypothesized that if a modification was made to make the bags air tight by removing air from the bags that this might be effective in preventing the contamination and spread of the carcinogenic mycotoxins.  The objective of this study was to evaluate the impact of low oxygen levels to reduce Aspergillus flavus and Aflatoxin production in corn seed stored at various levels of moisture content.  Corn at four moisture levels (12, 15, 18, and 21 percent) was placed into mason jars, half of which were air tight sealed and the other half had holes in the lids to promote some gas exchange. Ten inoculated kernels were placed in each jar, the kernels were colonized with a GFP  (Green Fluorescence Protein) hybrid strain of A. flavus, the kernels were used to identify the growth rate of the fungus. The air tight jars were sealed with greased lids to prevent airflow, while the other jars had three small holes in the lid.  Every air by moisture level treatment was replicated in triplicate and were incubated at 28°C for one month.  At the end of the experiment the jars were opened and a UV light was used to detect the fluorescence of the GFP A. flavus, and to determine how effectively the fungus spread under the different environmental conditions. Samples were taken, purified and analyzed by HPLC.   Spread of GFP A. flavus was low, yet observed only in non-sealed jars at 15 and 18% moisture contents.  Whereas in the highest moisture contents (18 and 21 %) the A. flavus toxin producing strain was the primary fungus and out competed the GFP hybrid strain.