Isolation and Identification of Indigenous Wine Yeasts and their Use in Alcoholic Fermentation

Abstract

Research background. In our study, spontaneous alcoholic fermentations were carried out to isolate non-Saccharomyces and Saccharomyces yeasts from grape must from different wine growing regions in Slovenia. Additionally, the diversity of native Saccharomyces cerevisiae strains was evaluated during the process. Experimental approach. During spontaneous alcoholic fermentations the yeast population of non-Saccharomyces and Saccharomyces yeasts was sampled. We used eleven microsatellite markers to determine the genetic diversity of S. cerevisiae strains. In addition, different proportions of the indigenous strains of S. cerevisiae, Hanseniaspora uvarum and Starmerella bacillaris were tested for their possible use in inoculated AF by monitoring the course of alcoholic fermentation and measuring the content of aroma compounds in wine. Results and conclusions. Sequencing of the ITS regions of ribosomal DNA showed that of 64 isolates 46 strains represent S. cerevisiae and 18 strains belong to non-Saccharomyces yeasts. The identified non-Saccharomyces yeast species were H. uvarum, Pichia kudriavzevii, Saturnispora diversa and S. bacillaris. The dendrogram grouped S. cerevisiae strains into 14 groups. The number of S. cervisiae strains isolated from the musts was 10 (Posavje), 11 (Podravje) and 25 (Primorska vine-growing region). On the other hand, the inoculated AF, in which the native S. cerevisiae strain predominated over H. uvarum and S. bacillaris, gave the most promising result due to the highest alcohol content, the lowest acetic acid concentration and the significantly higher concentrations of volatile thiols (3MHA and 3MH), 2-methylpropanol, 2-methylbutanol, 3-methylbutanol and 2-phenyl ethanol in the wine produced. Novelty and scientific contribution. We confirmed the potential use of indigenous S. cerevisiae and non-Saccharomyces yeasts in inoculated AFs, which allows the positive properties of the yeast strains to be expressed and good quality wines to be produced. Thus, the results are encouraging for winemakers to create different wine styles associated with a particular terroir using indigenous yeasts.