Genetic Diversity, Ochratoxin A and Fumonisin Profiles of Strains of Aspergillus Section Nigri isolated from Dried Vine Fruits
Abstract
We investigated ochratoxin A (OTA) contamination in raisin samples purchased from Slovak markets and determined the diversity of black-spored aspergilli as potential OTA and fumonisin (FB1 and FB2) producers. The taxonomic identification was performed using sequences of the nuclear ITS1-5.8s-ITS2 region, the calmodulin and beta-tubulin genes.
We obtained 239 isolates from eight fungal genera, of which 197 belonged toAspergillus(82%) and 42 strains (18%) to other fungal genera. OTA contamination was evidenced in 75% of the samples and its level ranged from 0.8 to 10.6 mu g/kg.
The combination of all three markers used enabled unambiguous identification ofA. carbonarius,A. luchuensis,A. niger,A. tubingensisandA. welwitschiae. The dominant coloniser, simultaneously having the highest within-species diversity isolated from our raisin samples, wasA. tubingensis.
Out of all analysed strains, onlyA. carbonariuswas found to produce OTA, but in relatively high quantity (2477-4382 mu g/kg). The production of FB1 and FB2 was evidenced inA. nigerstrains only.