Isolation of Aspergillus flavus strains from Bambara groundnut (Vigna subterranea (L.) Verdcourt) seeds and screening for the production of aflatoxin B1 and B2

Abstract

In Burkina Faso, Bambara groundnut is the second most important food legume after cowpea, especially in rural areas. However, this crop, due to certain conditions of production, storage or preservation is susceptible to be contaminated by potential mycotoxin producing fungi. The aim of this study was to evaluate the aflatoxinogenic capacity of Aspergillus flavus isolates isolated from Bambara groundnut seeds produced in Burkina Faso. Thus, 198 isolates of fungi belonging to section Flavi were isolated from 99 samples of Bambara groundnut seeds collected in the three agro-ecological zones of Burkina Faso. From the 198 isolates, 28 were identified as Aspergillus flavus. Then, we investigated their potential for aflatoxin B1 (AFB1) and B2 (AFB2) production by growing them on rice at 25°C for 7 days. AFB1 and AFB2 were extracted and quantified by liquid chromatography–mass spectrometry (LC-MS/MS). All of the strains (28) produced AFB1 at concentrations ranging from 46.987 μg kg^–1 to 1080.320 μg kg^–1. However, AFB2 was produced by 26 strains with concentrations ranging from 47.200 μg kg–1 to 1760.240 μg kg^–1. Globally, most of the tested strains produced higher levels of AFB1 than AFB2. The results obtained point out the risk associated with post-harvest fungi and the need for the development of storage technics to control them, for food security.