The aim of the thesis was to present the properties of acetic acid bacteria and microbial community in apple and balsamic vinegar. Vinegar is a solution of acetic acid that is processed through completion of sequential fermentations. Firstly, in alcoholic fermentation yeasts convert fermentative sugars to ethanol, followed by acetic acid fermentation, where the acetic acid is produced from ethanol by acetic acid bacteria. The diversity of acetic acid bacteria has significant affect in the production process and consequently also on sensory properties of the vinegar. Acetic acid bacteria predominate in both vinegars. The microbial community of apple cider is mostly made up of species Acetobacter pasteurianus, Komagataeibacter oboedinens, and K. saccharivorans, while species Gluconobacter europaeus, A. pasteurianus and A. malorum are most frequently present in balsamic vinegar. Besides acetic acid bacteria in vinegar, there are also found yeast and lactic acid bacteria. The most frequently present yeasts species in apple vinegar are Saccharomyces ludwigii, S. cerevisiae, Candida ethanolica and Pichia Membranifaciens, while the most frequently lactic acid bacteria genus present are Oenococcus and Lactobacillus. In balsamic vinegar appear yeast species C. lactis-condensi, C. stellata, Zygosaccharomyces bailii, Z. pseudorouxii, Z. mellis, Z. bisporus, Z. rouxii and S. cerevisiae.
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