BIODIVERSITY OF MYCOBIOTA IN PEANUT SEEDS, CORN AND WHEAT GRAINS WITH SPECIAL REFERENCE TO THEIR AFLATOXIGENIC ABILITY

Abstract

The fungal biodiversity in 30 samples, 10 of each of peanut seeds, corn and wheat grains were estimated on two isolation media (AFPA and DRBC). The aflatoxigenic ability of isolates related to Aspergillus section Flavi using CAM agar plates was also assessed. The results indicated that the mean moisture content was relatively low in peanut (8.05%) while it was relatively high in corn samples (10.45%). A limited number of peanut seeds but a large number of corn grains were fungi-free on both media. On AFPA, the aflatoxigenic species contaminated 9, 5 and 7 of peanut, corn and wheat samples respectively. On AFPA and DRBC, the total number of genera and species recorded on wheat were higher than those on corn and peanut and only three genera, Aspergillus, Penicillium and Fusarium were isolated from the three substrates. Aspergillus possessed more propagules on peanut than on corn and wheat, whereas Fusarium and Penicillium had more propagules on corn than on peanut and wheat. The aflatoxigenic species A. flavus, and A. niger were isolated from the three substrates. These two species showed higher propagules on peanut and corn than on wheat. P. chrysogenum, P. duclauxii and F. verticillioides were recorded from corn and wheat grains, P. aurantiogriseum and F. chalamydosporum from corn and P. brevicompactum, P. funiculosum from wheat and P. pinophilum and F. oxysporum from peanut only. Flourescence at 365 nm of 43 A. flavus and other 4 fungal strains recovered from the analyzed substrates and grown on CAM agar plates revealed that all A. flavus strains showed blue color with different intensities indicating aflatoxin B production, while the other 4 non-A. flavus strains showed negative results.