Preservation of diversity and oenological properties of wine yeasts during long-term laboratory maintenance: A study of strains of a century-old Tokaj wine yeast collection

Abstract

The effect of long-term laboratory maintenance on the biological diversity and certain oenolological properties of wine yeasts was investigated by the analysis of 17 strains isolated from Tokaj (Hungary) wines more than a century ago and maintained since then in culture collections. The analysis of the D1/D2 domains of the large subunit ribosomal RNA genes and the ITS sequences assigned them all to S. cerevisiae but divided them into two groups. One group showed sequence identity with wine strains occurring mainly in countries of the region. The combined results of the interdelta, RAPD, microsatellite-primed PCR (MSP), mtDNA and karyotype analyses found both groups diverse and defined each strain as unique, demonstrating that the long period of maintenance under identical conditions has not resulted in convergent evolution in their genomes. High diversity was detected also in certain phenotypic traits of oenological relevance (osmotolerance, killer phenotype, production of glycerol, ethanol, H2S and volatile acids). In the microvinification experiments all strains performed better than the laboratory strain S288c and were comparable to the industrial strain used as a control or even surpassed it in certain parameters. Thus, the oenological abilities of wine yeasts can be preserved over long periods of maintenance under laboratory conditions.