Illustration of Pre-harvest Peanut Seeds Mycoflora and Mycotoxins

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Authors

1 Botany and Microbiology Department, Faculty of Science, Sohag University, Sohag 82524, Egypt.

2 Plant Pathology Institute, Agriculture Research Centre, Giza, Egypt.

Abstract

Of pre-harvest peanut seeds (folded seeds), on two isolation media (1 % glucose and 1 % cellulose Czapeck’s agar), the gross fungal counts on glucose (325 colonies) was higher than on cellulose (272 colonies) per 20 samples (each, 10 seeds). Where, the average number of colonies per 10 seeds was higher on glucose (7-32 colonies) than on cellulose (3-21 colonies). Also, 6 % and 7.5 % of the seeds were free of filamentous fungi on the two isolation media, respectively. Using seed-plate method and without surface disinfection, 7 species of 5 genera were isolated and identified from peanut seeds on glucose (6 species of 5 genera) and cellulose (7 of 5) Czapeck’s agar at 18 ± 10 C. Of isolated genera, Aspergillus was superior in count (56 % and 53.3 % of fungal count, respectively) and frequency (85 % and 90 % of samples, respectively) on the isolation media. Of the genus, A. flavus had the highest count (34.5 % and 29.4 %) and frequency (each, 80 %). A. niger was less in count (21 % and 17.4 %) and in occurrence (each, 55 %) on the two media. Two species (Fusarium oxysporum and Penicillium citrinum) were detected in moderate frequencies (40 % and 30 % of the samples on the two media, respectively). F. oxysporum had the higher count (14.2 % and 16.2 % on the two media) compared with P. citrinum (each, 11.4 %). Cladosporium cladosporioides was low in occurrence (each, 20% of the samples) with counts 12 % and 11.4 %. A. fumigatus appeared on cellulose medium only whereas, Nectria haematococca on glucose only. Based on biological assay (brine shrimp test) and chemical detection (TLC and UV spectra), the ethyl acetate extracts of pre-harvest peanut seeds (approx. 15-20 days before harvest) proved to be non-toxic and mycotoxin free.

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