Occurrence of potentially toxigenic mould species in fresh salads of different kinds of ready-for-use vegetables

Abstract

In the mycological survey of fresh salads of different vegetables, the collected samples were tested for total counts of moulds with special attention paid to the presence of potentially toxigenic species. The survey also included the isolation and the identification of species, as well as the evaluation of mycotoxin biosynthesis ability of potential producers of ochratoxin A (OA) and sterigmatocystin (STC). Mould counts ranged from 10.0 to 4.7×10 2 cfu g-1. The most common moulds found in fresh salads were Cladosporium (42.89%), Pénicillium (25.78%), Aspergillus (14.67%) and Alternaria (6.89%). C. cladosporioides (40.44%), followed by A. niger (10.22%), P. aurantiogriseum (7.55%), A. alternata (6.89%) and Fusarium spp. (3.11%) were the most dominating species. Other species were represented with 2.22% (Eurotium spp.), 1.56% (Botrytis spp.), 0.67% (Phoma spp.), 0.44% (Geotrichum spp., Mucor spp., Phialophora spp.) and 0.22% (Emericella spp., Paecilomyces spp., Trichoderma spp., Xeromyces spp.). Twenty-two of 41 identified mould species were potentially toxigenic, which accounted for 46.18% of the total isolated population. The most frequent were the potential producers of ochratoxin A (17.77%). Potential producers of moniliformin were isolated in 3.11% of samples, while producers offumonisin and STC were found in 2.67% and 2.44% of samples, respectively. The tested isolates of OA producers did not demonstrate the ability to biosynthetise this mycotoxins, but two out of five isolates of A. versicolor were found to biosynthesise STC in doses of 109.2 ng mL-1 and 56.3 ng mL-1. The obtained results indicate that such products may threaten human health, considering that isolated species were potentially toxigenic, while isolates of A. versicolor also biosynthesised STS.