الفهرس 
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Abstract
English Summary
Food and feed spoilage mould fungi cause great economic losses worldwide. These fungi cause losses in dry matter or quality and some species can produce health-damaging mycotoxins. White, yellow corn grains and groundnut seeds were collected from cereal stores of four different districts of great Cairo governorate namely; Gesr El-Suez, Hadeik El-Kobba, El Zeitoun and El Haram. Seed borne fungi were isolated from these cereals on 3 different media (PDA, Nash and Coon’s) using standard agar plate method. Sixteen different fungal species belonging to 7 genera were isolated and identified mycologically, however 5 fungal isolates known of causing diseases and producing mycotoxins on cereals were selected for further research namely; P. carryophylum, F. verticilliodes, A. flavus, A. terreus and F. oxysporum.
Leaves of Mulberry plant (Morus nigra) were collected from Dekernis, Mansoura governorate-Egypt, and its aqueous extract was prepared and used for the preparation of silver nanoparticles (AgNPs). characterization of these green synthesized AgNPs using Uv/Vis absorbance and TEM showed that they were spherical in shape with nano size ranging from 4 to 8 nm.
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In vitro antifungal activities of the plant extract and AgNPs were evaluated against the selected seed borne fungi using poisoned food technique and agar well diffusion assay. The plant extract and AgNPs showed potent antifungal potential against the selected fungi which increased with increasing their corresponding concentrations in both assays.
Maximum reduction of the diameter of radial growth of the fungi using poisoned food technique were recorded at the high concentrations of plant extract and AgNPs (0.8%), causing reduction percentages against P. carryophylum, F. verticilliodes, A. flavus, A. terreus and F. oxysporum reached 23, 20%, 55, 49%, 26, 20%, 35, 22% and 28, 21%, respectively, compared to the non-treated fungi and those treated with Dithane M-45 fungicide.
In agar well diffusion assay, the plant extract and AgNPs caused considerable inhibition of radial growth of the seed borne fungi on PDA medium. At concentration of 1.6%, both agents inhibited the growth of the 5 selected fungi at percentages of 9, 18%; 20, 25%; 9, 11%; 10, 11% and 20, 30%, respectively, compared to the non-treated control and those treated with the synthetic fungicide. Statistical analysis for these results revealed
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the higher antifungal potency of the AgNPs compared with the plant extract.
The MIC of the plant extract and AgNPs using poisoned food technique were very low about 0.1%, however, in the agar well diffusion assay it was much higher for all tested fungi reaching at least 0.2% for P. carryophylum, F. verticilliodes and F. oxysporum in case of using AgNPs, and 0.4% on using the plant extract. The plant extract and AgNPs caused considerable reduction in the mycelial dry wt. of all selected seed borne fungi, in percentages ranging from 5.8-84%, compared to the non-treated control and those treated with the fungicide.
The plant extract and AgNPs showed potent antimycotoxin potential, as they reduced the level of total aflatoxins in corn grains treated with both agents separately, and infested with aflatoxigenic isolate of A. parasiticus into 0.35 and 0.13 μg total aflatoxins/ kg corn grain, respectively, compared with the corn grains treated with the aflatoxigenic isolate only having a concentration of 5.03 μg total aflatoxins/ kg corn grain.