engleski

Occurrence of mycotoxin-producing aspergilli in medicinal herbs

Microbial contamination of medicinal herbs occurs in the field, during harvest, transportation or storage. Since contamination with mycotoxins and mycotoxin producing moulds represents a special health hazard, 91 randomly sampled products with medicinal herbs (seeds, fruits and roots) collected in Zagreb were investigated for the presence of moulds and their in vitro mycotoxin-producing ability. Results showed that 69.2% of samples were contaminated with moulds with total yeast/mould count (TYMC) lower than 103/g. Among identified moulds, the most prevalent were Aspergillus species (61.9%). A. glaucus (30 %) was dominant species, followed by A. niger (25%), A. fumigatus (15%), A. nidulans (5 %), A. versicolor (3.33%), A. flavus (3.33%), A. candidus (3.33%), A. ochraceus (1.92%) and Aspergillus spp. (13.33%). HPLC (UV Vis or FLD detection) was used for analysis of toxigenic potential of isolated aspergilli in YES broth. A. niger (1/15) and 1/1 A. ochraceus were found to produce ochratoxin A (OTA) at concentrations 7.048 ng/mL and 20.795 ng/mL, respectively. A. nidulans (1/3) produced sterigmatocystin (STC) at 5.462 g/mL. Among A. glaucus strains 5/9 produced both OTA (44.46-4293.58 ng/mL) and STC (7.61-15.49 g/ml), while 12/22 produced only STC (0.70-72.82 g/mL). Aspergillus spp. (2/5) produced aflatoxins (AFs) at concentrations 0.36 and 13.08 ng/mL. Producers of OTA, AFs and STC were tested for mycotoxin production on cranberry and fennel fruits and nettles root as well. OTA-positive A. ochraceus strain produced OTA on nettles root and fennel fruits, AFs-positive A. parasiticus produced AFs only on fennel fruits, while STC-positive A. versicolor produced STC only on nettles root. The results indicate that some medicinal herbs are good substrate for growth of mycotoxin-producing Aspergillus species which present a potential health hazard due to mycotoxin hepatotoxicity, nephrotoxicity and carcinogenicity.

Aspergillus ; aflatoxin ; ocrhratoxin ; sterigmatocystin ; medicinal herbs

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