An official website of the United States government.
Isolation and characterization of experimentally-induced non-aflatoxigenic variant strains of Aspergillus parasiticus. Identification of the morphological variations in these strains. Determination of chemical, biochemical, and genetic characteristics of these variant strains with respect to development and aflatoxin production. Genetic evaluation of other A. parasiticus mutant strains with reduced sporulation, altered conidial morphology, and sclerotia formation.
Variant or mutant strains of Aspergillus parasiticus, with altered secondary metabolite production, will be produced either by serial transfers of nonsporulating mycelia on solid media or by genetic engineering involving specific aflatoxin pathway genes. A comparison of the morphological, biochemical, and molecular profiles of these parental aflatoxingeic A. parasiticus strains with their derivative variant or mutant strains will be made by (1) scanning electron microscopy demonstrating specific morphological differences in the mycelia, conidiophores, and sclerotia; (2) measurement of secondary metabolite profiles and bioconversion of aflatoxin pathway intermediates for assessing the biochemical parameters affecting altered toxigenicity; (3) genetic studies to determine the presence and expression of aflatoxin pathway and regulatory genes in wild-type and mutant strains; and (4) molecular measurements to determine the global regulatory elements governing fungal development and aflatoxin elaboration.