Molecular Identification of Aflatoxigenic Fungi in Some Foods from Selected Markets in Lagos

Abstract

Aflatoxigenic fungi are species of fungi that produce aflatoxins in food commodities. This study was aimed at screening different food samples in our local market for aflatoxigenic fungi using the aflatoxin regulatory gene (aflR gene). Six food samples (wheat, cowpea, rice, maize, melon and groundnut), were sourced from three different markets in Lagos metropolis (Mushin, Oyingbo and Mile 12). Fungi were isolated from these food samples and identified morphologically and microscopically. The genomic DNA was obtained using DNA isolation kits. The aflR gene was amplified from genomic DNA, nested, subjected to agarose gel electrophoresis and gel imaging. The Internal Transcribed Spacer (ITS) was also amplified from the genomic DNA for molecular identification of the organisms. The results showed that Aspergillus flavus were isolated from all the food samples from the three markets, while Aspergillus niger was present in rice, melon and wheat from Mile 12 market, maize and groundnut from Mushin market, rice and cowpea from Oyingbo market. A. flavus and A.niger were isolated from all the food samples when similar food samples from different market were mixed together. Only A. flavus amplicon from the nested polymerase chain reaction (PCR) showed approximately 400bp DNA fragment on the gel. This study has shown that PCR amplification of aflR gene has high specificity for detection of aflatoxigenic fungi in food samples thus, may be employed in screening food samples for contamination by aflatoxigenic fungi.