Isolation of Fungal Species and Aflatoxin Detection from Grinded Cereals Sold in Dutsin-Ma Metropolis

Abstract

Aflatoxins are the most common and potent mycotoxins produced mainly, by Aspergillus species, often found contaminating cereals. This study was aimed at isolating fungal species and detecting aflatoxins from grinded cereals sold in Dutsin-ma metropolis of Katsina State, Nigeria. Forty (40) cereal samples (Maize, Millet, Sorghum and Wheat), 10 of each were collected randomly from 3 different locations in Dutsin-ma metropolis. Standard microbiological procedures were used to isolate and identify fungal species on Potato Dextrose Agar (PDA) and fungal ATLAS [1,2] respectively. The predominant fungi isolated were species of Aspergillus, Mucor and Fusarium. Aspergillus niger had the highest incidence of 32.1%, Aspergillus flavus had 20.2%, followed by Mucor spp. with 13.1%, Aspergillus fumigatus with 11.9%, Aspergillus parasiticus had 8.3%, then Aspergillus lentulus and Fusarium oxysporum had 7.14% each. Presence of Aflatoxins were tested (out of the four aflatoxin types) in the samples using High-Performance Liquid Chromatography (H.P.L.C) (UV-VIS detector) by comparing the retention time of standards to the time on the peaks obtained from the samples during the HPLC analysis. Aflatoxins were detected in all three samples that were tested with the maize sample having the highest % height of B1 (48.10%), Millet had the highest % height of G1 (29.88%). G2 was not detected on the millet samples. All the other 2 samples had all three aflatoxins detected. Percentage height of aflatoxin peaks ranged from 16.60% – 48.10. This study revealed high contamination of grinded cereals by species of Aspergillus, Mucor and Fusarium. Aflatoxins B1, G1 and G2 were also detected, which makes their consumption a public health risk. Proper pre-harvest and post-harvest management of cereals coupled with proper cooking of cereal products before eating are recommended so as to reduce contamination and prevent possible intake of these toxins.