Determination of Aspergillus section Flavi andtheir aflatoxin and cyclopiazonic acidproduction patterns in naturally dried figs

摘要

Aspergillus section Flavi contamination in naturally dried figs were investigated in samples collected from orchards. Isolated fungi were identified using morphological and phenotypic characteristics. Isolates in Aspergillus section Flavi from fig were tested for aflatoxin (AF) and cyclopiazonic acid (CPA) production using thin-layer chromatography (TLC)-high performance liquid chromatography (HPLC) and TLC respectively. Of fig samples collected from 115 different orchards before any treatment, forty three (37.4%) were contaminated with Aspergillus flavus, whereas Aspergillus parasiticus contamination was rare - only in 4 samples (3.5%) of dried figs for two consecutive years. A. flavus is the predominant species among Aspergillus section Flavi members for figs (85.7%). In some sample groups, both nontoxic and aflatoxins B1 and B2 producing A. flavus strains were found together on the same fig sample; also both A. flavus (producing aflatoxins B1 and B2) and A. parasiticus (producing aflatoxins B1, B2, G1 and 02) were found together on the same fig sample. All aflatoxin producing A. flavus isolates also produced CPA. Most of the A. flavus strains produced aflatoxins 131 and B2 and CPA at the same time during the first and second year, with ratios of 71.9% and 62.5% respectively, averaging to 68.7%. A. flavus strains producing only AFB, and CPA were rare, with a ratio of 7.9% and 0% with an average of 6.2% for the first and second year,respectively. All A. parasiticus strains produced only aflatoxins B1, B2, GI and G2 but no CPA. A. tamarii, another member of Aspergillus section Flavi, is rarely present in Turkish figs.