Mycoflora of fresh chokeberry (Aronia melanocarpa) and ochratoxin-producing ability of Penicillium isolates

Black chokeberry (Aronia melanocarpa) is a plant with unique health-promoting properties due to the high content of vitamins and polyphenols in its fruits. Despite their high resistance to spoilage, chokeberry fruits may get contaminated with mycotoxin-producing fungi. In the present study, samples of chokeberry fruits were collected from seven different sites in Bulgaria and their fungal profile was investigated. The most common moulds in fresh chokeberry were Penicillium sp. (77.5% out of all isolates), followed by Alternaria sp. (14.5%) and Bothrytis sp. (8%). Eighteen randomly chosen Penicillium isolates were further screened by enzyme-linked immuno sorbent assay (ELISA) for their ability to produce ochratoxin A (OTA) in liquid yeast extract sucrose medium. Four of the tested isolates (no. 11 from the region of Panagiurishte, no. 2 and 10 from the region of Plovdiv and no. 47 from the region of Koprivshtitsa) showed ability to produce OTA in concentrations 15.42, 14.62, 19.75 and 20.97 ng/ml, respectively (ELISA screening). High-performance liquid chromatography with post column fluorescence derivatisation analysis was also performed for all OTA-positive isolates. The maximum estimated OTA concentration was 27.47 ng/ml for isolate 47 from the region of Koprivshtitsa.