Thesis (M.Sc.) - Cairo University - Faculty of Science - Department of Botany Microbiology

This study was aimed at investigating the impact of microwave heating and gamma radiation effect on some fungi isolated from different food stuffs. The study included phenotypic, biochemical and molecular studies. Fifty six fungal isolates were obtained and identified. The most common fungi belong to two main genera, aspergillus and penicillium. The identified fungal species were treated with microwave radiation at two different power levels (540 and 720 W) for different exposure times started from 10 to 180 s. Gamma irradiation was applied on the fungal species, the irradiation was carried out at doses of (0.1, 0.2, 0.3, 0.4, 0.5, 1, 2, 3 and 5 kGy), at dose rate of 1.1 kGy/h. Aspergillus niger was selected to be the studied fungal species as it showed a morphological changes after irradiation. Three phenotypically different mutants were obtained and purified on Czapeck Dox{u2019}s agar media. A mutant M1 was isolated after microwave irradiation at 720 W for 120 s, while two mutants M2 and M3 were isolated after gamma irradiation at doses of 1 and 3 kGy, respectively. SEM micrographs showed clear morphological changes in conidiophores, conidial heads and conidia among all strains. The studied ultrastructure by TEM microscope illustrated occurrence of slight damage to the obtained mutants in comparison with the parent strain

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