Abstract
The aim of study was to detect the microscopic filamentous fungi from wine surface of sterilized grapes berries of Slovak origin. We analyzed 21 samples of grapes, harvested in the year 2012 of various wine-growing regions. For the isolation of species we used the method of direct plating surface-sterilized berries (using 0.4% freshly pre-pared chlorine) on DRBC (Dichloran Rose Bengal Chloramphenicol agar). The cultivation was carried at 25±1°C, for 5 to 7 days. A total number of 2541 fungal isolates pertaining to 18 genera including Mycelia sterilia were recovered. Isolates of genus Alternaria were found in all of tested samples with the highest relative density 56.4%. The second highest isolation frequency we detected for genus Fusarium (90.48% positive samples), but with low relative density (31 isolates and 2.99% RD). Another genera with higher isolation frequency were Cladosporium (Fr 85.71%, RD 14.6%), Mycelia sterilia (Fr 85.71%, RD 4.25%), Penicillium (Fr 80.95%, RD 13.42%), Botrytis (Fr 71.43%, RD 2.95%) Rhizopus (Fr 66.66%, RD 1.34%), Aspergillus (Fr 57.14%, RD 0.87%), Epicoccum (Fr 47.62%, RD 1.22%), Trichoderma (Fr 42.86%, RD 1.26%). Isolation frequency of another eight genera (Arthrinium, Dichotomophtora, Geotrichum, Harzia, Chaetomium, Mucor, Nigrospora and Phoma) was less than 10% and relative density less than 0.5%. Chosen isolates of potential producers of mycotoxin (species of Alternaria, Aspergillus, Fusarium and Penicillium) were tested for the ability to produce relevant mycotoxins in in vitro conditions using TLC method. None isolate of Aspergillus niger aggregate (13 tested) did not produce ochratoxin A – mycotoxin monitored in wine and another products from grapes berries. Isolates of potentially toxigenic species recovered from the samples were found to produce another mycotoxins: aflatoxin B1, altenuene, alternariol, alternariol monomethylether, citrinin, diacetoxyscirpenol, deoxynivalenol, HT-2 patulin, penitrem A and T-2 toxin in in vitro conditions. In conclusion, another research should be performed to detect the occurrence of these mycotoxins in grapes, must, wine and another products from grape.
Highlights
MATERIAL AND METHODSThe grape microbiota is complex and includes filamentous fungi, yeasts and bacteria with different physiological characteristics and effects on wine production (Rousseaux et al, 2014; Barata et al, 2012)
Mycotoxins are secondary metabolites produced by filamentous fungi that have been detected in food commodities, including grapes and wine (Serra et al, 2005)
Ochratoxin A is a secondary metabolite produced by filamentous fungi of the genera Aspergillus and Penicillium present in a wide variety of foodstuffs (Amézqueta et al, 2012)
Summary
The grape microbiota is complex and includes filamentous fungi, yeasts and bacteria with different physiological characteristics and effects on wine production (Rousseaux et al, 2014; Barata et al, 2012). Mycotoxins are secondary metabolites produced by filamentous fungi that have been detected in food commodities, including grapes and wine (Serra et al, 2005). Ochratoxin A is a secondary metabolite produced by filamentous fungi of the genera Aspergillus and Penicillium present in a wide variety of foodstuffs (Amézqueta et al, 2012). It has been classified as a possible human carcinogen (group 2B) by the International Agency of Research of Cancer (IARC, 1993). The ability of isolates of potentially toxigenic species to produce the most important mycotoxins was determined by the means of thin layer chromatography
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