Mycobiota and mycotoxins of Egyptian peanut (Arachis hypogeae L.) seeds

Abstract

Sixty-three species in addition to 3 varieties of 21 genera were isolated from 20 samples of each of untreated (51 species + 3 varieties of 21 genera and 51.24 × 103 cfu g_1 dry weight seeds), roasted (28 + 2 of 12 and 11.5×103 cfu) and roasted with salt (28 + 2 of 7 and 7.5×103 cfu) on dextrose-Czapek's agar at 28°C using dilution-plate method. The dominant fungal genera with their respective species on three types of seeds were Aspergillus (A. niger, A. flavus and A. ficuum), Penicillium (P. citrinum) and Fusarium (F. oxysporum). Based on biological, TLC, spectrophotometeric and ELISA assays, fourteen samples (23.3%) out of 60 tested proved to be toxic with different mycotoxins; aflatoxins, sterigmatocystin, ochratoxins, diacetoxyscirpenol and zearalenone. Also, mycoflora and myctoxins of six cultivars, widely cultivated in Upper Egypt were studied as pre-storage and post-storage in normal store for 3, 6, 12 and 24 months. A total of 28 species belonging to 14 genera were identified on dextrose-Czapek's agar medium (25 species of 12 genera) and cellulose-Czapek's agar medium (24 of 12) using dilution-plate method at 28°C. Aspergillus (A. niger, A. flavus and A. fumigatus), Fusarium (F. oxysporum) and Penicillium (P. citrinum) were the most prevalent fungal genera and species and their counts increased with lengthening of storage period. Cultivars were non-toxic, but toxins production appeared after 12 and 24 months of storage on two and three cultivars, respectively. © 2008 Asian Network for Scientific Information.