Nefisa M.A. El-Shayeb

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The effects of black pepper, cinnamon, peppermint, cumin, ginger and clove on growth and aflatoxin formation of Aspergillus flavus were studied in rice powdercorn steep (RC) medium. The effects of the first five spices were judged to be inhibition of aflatoxin formation rather than of mycelial growth. Clove completely inhibited both mycelial growth and(More)
The activities of three natural coumarins, xanthotoxin and bergapten (fromAmmi majus, Umbelliferae) and psoralene (fromFicus cycomorus, Moraceae), were tested against mycelial growth and aflatoxin production of a toxigenic strain ofAspergillus flavus grown in a rice/corn steep liquor medium. Two other natural chromones, khellin and visnagin (fromAmmi(More)
Aspergillus niger β-glucosidase was modified by covalent coupling to periodate activated polysaccharides (glycosylation). The conjugated enzyme to activated starch showed the highest specific activity (128.5 U/mg protein). Compared to the native enzyme, the conjugated form exhibited: a higher optimal reaction temperature, a lower Ea (activation energy), a(More)
Rice powder-corn steep (RC) medium proved to be the most suitable among 6 nutrient liquid media for both aflatoxin formation and mycelial growth by the Aspergillus flavus strain No. 182, isolated locally. The production of aflatoxins by the mould was studied in relation to some cultural conditions on RC medium. Highest aflatoxin yields (2527 microgram/50(More)
A study was conducted to determine the ability of five marine algae of the phaeophyta class, namely, Sargassum despiense, Turbinaria decurrense, Dilophus ligulatus, Cystoseira myrica and Padina pavonia, to act against mycelial growth and/or aflatoxin accumulation by a toxigenic strain of Aspergillus flavus, at different levels, in rice corn steep medium.(More)
In all the fifteen investigated Aspergillus flavus and A. parasiticus strains the maximum quantities of aflatoxins, produced on rice powder-corn steep (RC) medium, ranged from 1.17 to 23.29 times as much as those produced on yeast extract-sucrose (YES) medium. The shake cultures lowered aflatoxin formation. The maximum yields of aflatoxins did not coincide(More)
In all the investigated Aspergillus ochraceus and A. alliaceus strains the maximum quantities of ochratoxins produced on yeast extract-sucrose (YES) medium exceeded that detected on wheat solid medium except A. ochraceus 67. The shake cultures lowered ochratoxins formation. The maximum yields of ochratoxins did not coincide with maximum fungal growth. In(More)
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