Fungal contaminants and aflatoxin quantification in peanut (Arachis hypogaea L.) from Gedeo Zone of Southern Ethiopia

Abstract

Peanut (Arachis hypogaea L.) is one of the most important oil crops and agricultural export commodities. Its export can be affected by mycotoxigenic fungi. However, the quality of peanut is contaminated with aflatoxins, a group of mycotoxins produced by mycotoxigenic fungi of the genus Aspergillus, Penicillium and Fusarium. The aim of this study is to assess the occurrence and abundance of mycotoxigenic fungi in peanuts. Fungal abundance in peanut samples was evaluated using morphological and microscopic characterization techniques. The totals of 16 samples were collected from Dilla, Wenago, Bule and Yirgachefe districts from Gedeo zone of Ethiopia. All samples were collected randomly. Potato Dextrose Agar was used for isolation and identification of fungi. Quantitative analysis of mycotoxins was done by using ELISA method. The result indicated that total mycotoxigenic fungal counted up to 86.7% from locally collected peanut samples. Five fungal genera were identified namely, Aspergillus spp. (40 %), Penicillium spp. (31.7%), Fusarium spp. (15%), Rhizopus spp. (8.3%), and Mucor spp. (6.7%). Although peanut samples from different places resulted in different percentages of mycotoxigenic fungi genera, the chi-square analysis resulted that there were no significant differences among the five fungi isolates. Thus, the results showed all the five fungi isolates had the same response on peanut samples. The concentration of mycotoxins detected from peanuts samples ranged from 0 μg/kg to 1932.2 μg/kg. The susceptibility of peanuts samples to various fungal genera is a considerable economical challenge for peanut producers. Therefore, this study confirmed that further in-depth studies are required to determine the type of mycotoxin produced by toxigenic fungal species in peanut.