Studies on The Fungus Flora and Aflatoxin Production of Cotton Seeds in Egypt

Eleven genera and 31 species in addition to 2 species varieties were isolated from stored cotton seeds collected from different localities in Egypt. The most common species encountered on 2% glucose-Czapek's agar at 28°C using the dilution and the seed plate methods were: Aspergillus niger, A. flavus, A. terreus, A. tamarii, Mucor racemosus and Rhizopus stolonifer. On 2% cellulose-Czapek's agar, A. niger, A. flavus, A. terreus, A. fumigatus, A. zonatus, Mucor racemosus and Rhizopus stolonifer were more frequently encountered. Screening of fungal species and strains isolated for aflatoxin production by the fluorescence technique revealed that, only two strains of A. flavus, two strains of A. oryzae and one strain of A. fumigatus were positive for aflatoxin production. Only aflatoxin B2 was produced by A. flavus and the optimal conditions for toxin production on synthetic agar medium is described.