Characterization of aflatoxin producing Aspergillus flavus from food and feed samples

Aspergillus flavus is one of the major producers of aflatoxin and can contaminate wide range of agricultural commodities either in field or in storage. 15 presumptive Aspergillus flavus has been isolated from 30 feed and grain samples. All the isolates were morphologically similar to Aspergillus flavus type strains. All the isolates were found to be aflatoxigenic. DNA sequencing of 5.8 s rDNA confirmed all of them to be Aspergillus flavus. Only 1 isolate possessed all the seven toxigenic gene (aflR, aflS, aflQ, aflP, aflD, aflM, and aflO) while aflP & aflQ were most prevalent in the isolates. All the isolates possessed at least three toxigenic genes. Toxin producing ability in solid culture media showed that 11 isolates isolates were able to produce both aflatoxin B1 & B2. More than 90% isolates produced aflatoxin B1 ranging 7-22 mu g/g of agar. This study alarms us about the potential risks of Aspergillus flavus to public health if contaminate agricultural commodities such as grains or raw materials such as poultry feed. Proper harvest and storage management is required to reduce the risk of aflatoxin in feed and grains.