SPECIES OF GENUS ASPERGILLUS ON GRAPE SLOVAK ORIGIN

Abstract

The aim of this study was to detect species of genus Aspergillus from wine grapes (berries, surface sterilized berries - endogenous mycobiota, from damaged berries and grape juice) of Slovak origin. We analyzed 20 samples of grapes, harvested in 2011 from various wine-growing regions. For the isolation of species we used the method of direct plating berries, surface-sterilized berries (using 0.4% freshly pre-pared chlorine), and damaged berries on DRBC (Dichloran Rose Bengal Chloramphenicol agar). For the determination of fungal contamination of grape juice, we used plate-dilution method and DRBC as medium. The cultivation in all modes of inoculation was carried at 25±1°C, for 5 to 7 days. After incubation Aspergillus isolates were inoculated on the identification media. Representatives of the genus Aspergillus were isolated from 13 samples berries, 7 samples of surface-sterilized berries, 4 samples of damaged berries and 9 samples of grape juice. Overall, representatives of aspergilli were detected in 90% of samples (75 isolates). In this work we focused on the detection of potential producers of ochratoxin A belonging to the genus Aspergillus. Isolates, potential producers of ochratoxin A (Aspergillus niger aggregate and Aspergillus westerdijkiae), were after their identification inoculated on YES medium (Yeast Extract Sucrose Agar) and after 14 days of incubation at 25±1°C, in the dark, we tested them for their ability to produce ochratoxin A using thin layer chromatography. Out of the 16 isolates from isolated potential producers of ochratoxin A none of the isolates of Aspergillus niger aggregate (13 tested) produced ochratoxin A. The isolate of Aspergillus westerdijkiae (1), isolated from the surface-sterilized berries, produced ochratoxin A.