ABSTRACT
The microbiological characteristics of the grapes are made up of a wide variety of microorganisms, including filamentous fungi. Their presence in grapes is traditionally associated with deterioration in quality. The health of the grapes is very important for obtaining quality wine. The objective of this study was to investigate the diversity of mycobiota on the surface and inside of different grapevine varieties at harvest time in the temperate climate of Slovakia and to identify potentially pathogenic isolates of Aspergillus and Penicillium producing selected mycotoxins. During the 2021 grape harvest, grapes were collected from the Small Carpathians wine region. Eleven grape samples were analyzed by the plating method and plating method with surface disinfection. Emphasis was placed on Aspergillus and Penicillium species because of their importance in mycotoxin production. Of the 605 fungal strains detected, 11 genera were identified in the exogenous mycobiota. The most common and abundant genera were Alternaria and Botrytis. In the genus Aspergillus, A. section Nigri is the most abundant, while in the genus Penicillium, P. raistrickii reached the highest frequency and abundance. Of the 379 strains detected and identified from the endogenous mycobiota, the most common genera were again Alternaria and Botrytis and the most abundant genus was Botrytis. Penicillium species were detected in 17% of all fungi found, with P. raistrickii dominating. The A. section Nigri reached only 4% of the relative density of all isolates. Potentially toxigenic Aspergillus and Penicillium species were tested for toxinogenity by thin layer chromatography. The most important mycotoxin-producing species found were A. section Nigri but without ochratoxin A production.
ABSTRACT
The aim of the study was to analyse selected aspects of the natural variability of selected varieties of Vitis vinifera. Grapevine is one of the most popular and desirable crops in the world due to the great tradition of wine production, but grape extracts also have a wide range of pharmaceutical effects on the human body. It is important to identify different varieties for the conservation of genetic resources, but also for commercial and cultivation purposes. The variability of conserved DNA-derived polymorphism profiles, as well as microbial characteristics, were analysed in this study. Six different varieties of Vitis vinifera L. were used in the study: Cabernet Savignon, Chardonney, Welschriesling, Weisser Riesling, Gewurztramines and Gruner Veltliner. Genetic polymorphism was analysed by CDDP markers for WRKY genes. Polymorphic amplicon profiles were generated by all primer combinations used in the study. Gruner Veltliner and Welschriesling were the most similar, with a similarity value at 0.778. Microbiological quality of grape and antimicrobial activity against Gram-positive and Gram-negative bacteria and yeasts were analysed further. The plate diluting method for microbial quality and the disc diffusion method for antimicrobial activity were evaluated. The number of total count of bacteria ranged between 3.12 in Cabernet Sauvignon to 3.62 log cfu/g in Gruner Veltliner. The best antimicrobial activity showed Gewurztramines against Salmonella enterica, Yersinia enterocolitica, Pseudomonas aeroginosa, Staphylococcus aureus, Listeria monocytogenes, Candida albicans, Candida krusei, and Candida tropicalis. The best antimicrobial activity was found against Enterococcus faecalis in variety Weisser Riesling.
