Alcoholic fermentation is a polimicrobial process involving a large number of genera and species of yeast and bacteria. The major yeast genera involved in this process belongs to the Saccharomyces spp. The aim of this study was the isolation, identification and determination of genetic diversity of indigenous Saccharomyces cerevisiae natural population taken from cv. Plavac mali from secluded wine growing areas of Southern Croatia. Must samples were taken during the spontaneous alcoholic fermentation followed by yeast isolation. A total of 40 isolates that were physiologically confirmed to belong to the Saccharomyces sensu stricto group were furthermore differentiated by molecular methods. PCR-RFLP analyses of the internal transcribed spacer (ITS1) region of the 18S ribosomal DNA identified 37 of the isolates as S. cerevisiae and two of the isolates as S. bayanus/pastorianus. All isolates were further analyzed by RAPD fingerprinting. The results of this study showed that in some cases the RAPD assay may be useful to separate species within the Saccharomyces sensu stricto group. The molecular analysis confirmed genetic diversity of S. cerevisiae indigenous population and additionally the involvement of indigenous S. paradoxus and S. bayanus was determined.
The population structure of Saccharomyces cerevisiae has indicated that each vineyard is characterized with particular S. cerevisiae microflora. It is an important step towards the preservation and exploitation of yeast biodiversity in Southern Croatia
