Level of Aflatoxins in Selected Cereals in Ekiti State, Nigeria

Abstract

Aflatoxins are family of toxins produced by certain fungi found on agricultural crops such as maize (corn), peanuts, cottonseed, and nuts. The ingestion of such mycotoxin contaminated grains by animals and human beings has enormous public health significance. This has necessitated the evaluation of effects of Asparagus africanus (Lam - whole plant) extracts on aflatoxins production by fungi isolated from selected foods in Ekiti State, Nigeria. A total of 240 food samples were collected across the 16 Local Government areas in rural open markets. The food samples analyzed were: Igbemo rice Oryza sativa igbemo curtivar), maize (Zea mays) and groundnut (Arachis hypogaea). Aflatoxin-producing fungi and non aflatoxin producing fungi were isolated and identified using morphological method of identification on PDA and microscopic with lactophenol cotton blue stain. The molecular identification of the isolates was done using internal transcribe spacer (ITS) region. A total of 70 samples that contain Aspergillus spp were subjected to ELISA test to quantify and identify types of aflatoxins that were present in them. It was revealed that four types of aflatoxins were present in the food samples (AFB1, AFB2, AFG1, and AFG2). Also, different species of isolates were obtained from the samples viz: Aspergillus flavus, Aspergillus niger, Rhizopus stolonifer, Mucor mucedo, A. parasiticus, Neurospora crassa, Botrytis cinerea, Fusarium oxyporum and Penicillium oxalicum. Aspergillus flavus was prevalent among the isolates. The molecular identification showed three of the isolates were Aspergillus flavus with different percentage of ITS4 rDNA identity. The level of aflatoxins in some of the food samples analyzed is of great concern because of its ability to cause disease (in man and animal) and these toxins are introduced mostly during storage, that is, post-harvest.