Isolation of culturable yeasts from market wines and evaluation of the 5·8S-ITS rDNA sequence analysis for identification purposes

Abstract

Aims: To test the possibility that wines available in the marketplace may contain culturable yeasts and to evaluate the 5·8S‐ITS rDNA sequence analysis as adequate means for the identification of isolates. Methods and Results: As a case study, typical Greek wines were surveyed. Sequence analysis of the 5·8S‐ITS rDNA was tested for its robustness in species or strain identification. Sixteen isolates could be assigned into the species Brettanomyces bruxellensis, Saccharomyces cerevisiae and Rhodotorula pinicola, whereas four isolates could not be safely identified. B. bruxellensis was the dominant species present in house wines, while non‐Saccharomyces sp. were viable in aged wines of high alcohol content. Conclusions: Yeast population depends on postfermentation procedures or storage conditions. Although 5·8S‐ITS rDNA sequence analysis is generally a rapid method to identify wine yeast isolates at the species level, or even below that, it may not be sufficient for some genera. Significance and Impact of the Study: This is the first report to show that commercial wines may possess diverse and potentially harmful yeast populations. The knowledge of yeasts able to reside in this niche environment is essential towards integrated quality assurance programmes. For selected species, the 5·8S‐ITS rDNA sequence analysis is a rapid and accurate means.