The molecular and analytical methods reveal aflatoxin B1-producing Aspergillus flavus isolated from ready-to-eat peanut samples are resistant to the antifungal agent methyl-thiophanate

Abstract

The peanut is a product of high nutritive value and an economically important crop. However, peanuts can be contaminated during storage with Aspergillus flavus, which produces aflatoxins. In humans, aflatoxins can cause hepatocellular carcinoma. Exposure of animals to aflatoxins can result in weight loss and generate residues in meat and milk. The objective of this study was to isolate and identify aflatoxigenic fungi, to quantify the production of aflatoxin B1, and to correlate its production with resistance to the antifungal agent methyl-thiophanate (MT) in ready-to-eat peanuts samples. Nine of the 50 samples selected were found to be contaminated with A. flavus by PCR amplification of the ITS region. In addition, three genes of the aflatoxin B1 biosynthesis pathway were amplified. HPLC analysis revealed that the isolates produced high levels of aflatoxins ranging from 4 to 285 μg/mL. Furthermore, the isolate producing the highest concentration of aflatoxin (285 μg/mL) exhibited the highest resistance to antifungal MT (MIC ≥ 250 μg/mL), factors that might be related. The present results confirm the presence of aflatoxin-producing fungi resistant to MT in peanut samples, which may pose health risks to consumers.