Molecular Characterization of Mycotoxin Producing Moulds and Mycotoxins Determination from Stored Grains and Legumes

Cereals and legume are among the staple food sources for people living in developing countries. 160 samples of the stored rice, maize, wheat and groundnuts were randomly collected from 3 different markets. They were stored for a period of 4 months in different packaging materials and analysed for the presence of mycotoxigenic moulds and mycotoxins production. Standard microbiological and molecular methods were used in the isolation and identification of moulds. A multimycotoxin method based on Liquid Chromatography tandem mass spectrometry was applied to investigate both the qualitative and quantitative occurrence of mycotoxins. Mycotoigenic moulds species identified using 18S rRNA sequences as well as their percentage occurrence were Aspergillus flavus (46%) followed by Aspergillus tamarii (23%), Aspergillus niger (18%), and Penicillium chrysogenum (9%) while the least was Aspergillus brunneoviolaceus (4%). The mycotoxins detected were Aflatoxin B1, Aflatoxin B2, Aflatoxin G1, Aflatoxin G2, Ochratoxin A, Citrinin, Dihydrocitrinone, Fumonisin B1, Fumonisin B2, Fumonisin B3, Fumonisin B4, Zearalenone, Deoxynivalenol and Nivalenol. The largest concentration of mycotoxins detected from stored grains and legumes were fumonisin (1350 ± 10.000 µg/kg), followed by aflatoxins (1265.3 ± 1.327 µg/kg), then Citrinin (Dihydrocitrrinone) (709.8 ± 1.039 µg/kg), Trichothecenes: (Nivalenone Deoxynivalenone) (642.2 ± 1.900 µg/kg), Ochratoxin A (371.8 ± 1.616 µg/kg), and the least being Zearalenone (358.5 ± 2.500 µg/kg). Rice (1286.3 ± 29.689 µg/kg) contained the largest amount of the various mycotoxins, followed by wheat (1166.8 ± 0.901 µg/kg), and then groundnuts (1142.9 ± 10.488 µg/kg) while maize (1111.6 ± 9.810 µg/kg) had the least quantity of mycotoxins. The stored grains and legumes were mainly contaminated with Aspergillus species and contained different mycotoxins of public health importance. The need for proper harvest and storage of grains and legumes cannot be overemphasized.