Identification of ochratoxin A-producing micromycetes
2025
Pivka Soňa | Jevinová Pavlina | Pipová Monika | Regecová Ivana
This study focused on the identification of microscopic filamentous fungi isolated from food commodities (chicken eggs, fermented green coffee beans, and dried marjoram) and the evaluation of their ability to produce ochratoxin A (OTA). A total of 179 isolates (93 from eggshells, 34 from coffee, 52 from marjoram) underwent phenotypic and genotypic identification. Phenotypic traits were assessed macroscopically and microscopically; genotypic identification was performed using conventional PCR and verified by ITS (internal transcribed spacers) region sequencing. Three complementary methods were used to assess OTA production: detection of the otanpsPN gene, cultivation on coconut cream agar, and thin-layer chromatography. Identified species included Aspergillus niger, A. ochraceus, A. westerdijkiae, A. carbonarius, A. tubingensis, and Penicillium verrucosum. Molecular analysis corrected the misclassification of two A. carbonarius and one A. tubingensis isolate, reidentified as A. niger. OTA production was confirmed by all methods in most isolates. Notably, only one A. niger isolate from coffee carried the biosynthetic gene. Two A. tubingensis isolates, despite being considered non-ochratoxigenic, also showed OTA production. The findings underscore the importance of combining morphological and molecular tools in fungal identification and highlight the need for multi-method approaches in evaluating the toxigenic risk of foodborne fungi.
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