Isolation of Aspergillus section Flavi and determination of aflatoxins in Bambara groundnut sold in Cotonou main markets (Benin)

Abstract

Legumes such as cowpea (Vigna ungiculata) and Bambara groundnut (Vigna subterranean) are the most sought in Benin and in the West Africa sub-region. These legumes are an important protein source because of their high content of essentials amino acids. But, like many dried agricultural and food products, they are subject to contamination by molds and mycotoxins during storage. In order to assess the contamination of Bambara groundnuts, by the most dangerous and widespread mycotoxins in Africa (aflatoxins), especially in Benin, this study was conducted in Cotonou (Benin) main markets. Thirty-five (35) samples of Bambara groundnuts were collected from six (6) different markets in Cotonou. The fungi are isolated and identified morphologically on different media after direct culture. The species of Aspergillus section Flavi aflatoxigenic potential are evaluated and the contamination of samples by aflatoxins was determined by Thin Layer Chromatography (TLC). The results of this study showed that the average water content of Bambara groundnuts samples ranged from 4.85 to 9.35%. The main species of mold isolated are Mucor spp., Rhizopus spp., Alternaria sp., and Aspergillus spp. Forty-six (46) strains of Aspergillus section Flavi were isolated on Potatoes Dextrose Agar (PDA). All of them have been identified as aflatoxigenic strains and were divided into different groups according to their morphological appearance and secondary metabolites. Twentytwo samples (62.85%) of Bambara groundnuts were contaminated by aflatoxins. This study showed that Bambara groundnuts which sold in the main markets of Cotonou constitute a health risk for populations.