Fungi Associated with Maize and Sorghum Grains and their Potential for Amylase and Aflatoxins Production

Abstract

USING direct-plating technique, thirty-nine species belonging to 16 fungal genera were isolated from maize and sorghum grain samples (20 samples each) on Czapek's agar (Cz) and Czapek's supplemented with 40% sucrose agar (Cz40S) media at 28 degrees C. Widest spectrum of genera and species were recorded on sorghum (16 genera and 35 species) compared with maize grains (8 and 19). The highest total count (139 CFUs/100 grains) and the number of genera (14) and species (27) were identified from sorghum grains on Cz medium. The most common fungi on the grains tested were Aspergillus flavus, A. niger, Eurotium amstelodami, E. rubrum, E. repens, Fusarium verticillioides and Rhizopus stolonifer. Among 129 isolates screened for their abilities to produce amylase enzyme, 102 isolates could produce this enzyme, of which A. terreus exhibited the highest production (EI=1.73). HPLC analysis revealed that out of 6 strains of A. flavus tested, strain No. AUMC 11311 showed the highest production of aflatoxin B-1 and B-2 while the highest value of aflatoxin G(2) was produced by strain No. AUMC 11317. It could be concluded that fungi growing on grains and have the abilities of producing enzymes and/or aflatoxins might cause deterioration and spoilage to these grains.