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

Not all A. flavus and A. parasiticus are aflatoxigenic. - Eight strains were aflatoxigenic and three were non aflatoxigenic out of eleven strains. Five strains of aflatoxinogenic fungi were A. flavus var. columnaris, two strains were A. parasiticus, and one strain was A. flavus. Three isolates were n o n-aflatoxinogenic. Two of which were A. flavus var columnaris and one A. flavus. - All aflatoxin-producing strains could release both aflatoxin B and G groups - Aflatoxin production was affected by broth type as shown in A. flavus var. columnaris strains 9022, 9024, 9025, 9030, 9031 A. flavus strain 9027 and A. parasiticus strains 9029, 9032. - In spite of, TLC distinguished between aflatoxin-producing and non-producing strains, it failed in some cases to detect aflatoxin- producing strains because instability of aflatoxin production may occur in certain toxinogenic strains. - Multiplex RT-PCR for the selected genes also showed a good correlation between aflatoxin gene expression and aflatoxin production. - Expression of nor-1 (Afl-D), omt- B (Afl-O), omt-A ((Afl-P)) and ord-A (Afl-Q) genes provided useful differentiation of aflatoxigenic and non- aflatoxigenic strains of A. flavus and A. parasiticus. - The expression of the selected genes varied with regard to the aflatoxin- producing ability and types of media

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