title: Authentication and identification of Saccharomyces cerevisiae 'flor' yeast races involved in sherry ageing.
abstract: Yeasts involved in velum formation during biological ageing of sherry wine have to date been classified into four races of Saccharomyces cerevisiae (beticus, cheresiensis, montuliensis, rouxii) according to their abilities to ferment different sugars. It has been proposed that race succession during biological ageing is essential for the development of the organoleptical properties of sherry wines. In this work we studied the physiological characteristics, the molecular differentiation and the phylogenetic relationships of the four races employing type and reference strains from culture collections and natural environments. Using restriction analysis of the ribosomal region that includes the 5.8S rRNA gene and internal transcribed regions (5.8S-ITS) we were able to differentiate 'flor' and non-'flor' S. cerevisiae yeast strains. However, no correlation between fermentation profile, mitochondrial DNA restriction analysis or chromosomal profiles and these races was found. Moreover, sequences of the D1/D2 domain of the 26S rRNA gene and the 5.8S-ITS region from these strains were analysed and no genetic differences were noted suggesting that 'flor' yeast cannot be grouped into four different races and the four races are identified as S. cerevisiae. Since the yeasts isolated from velum in sherry wine present a unique 5.8S rRNA pattern different from the rest of the Saccharomyces cerevisiae strains we propose that they should be included as a single race or variety inside the S. cerevisiae taxon.
authors.affiliation: Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos (CSIC), PO Box 73, 46100 Burjassot, València, Spain; CECT (Spanish Type Culture Collection), Universitat de València, Burjassot, València, Spain.
authors.forename: Braulio
authors.initials: B
authors.lastname: Esteve-Zarzoso
authors.forename: M Teresa
authors.initials: MT
authors.lastname: Fernández-Espinar
authors.forename: Amparo
authors.initials: A
authors.lastname: Querol
mesh_terms: D001483:Base Sequence; D050260:Carbohydrate Metabolism; D017931:DNA Primers; D005285:Fermentation; D005511:Food Handling; D016133:Polymerase Chain Reaction; D015203:Reproducibility of Results; D012441:Saccharomyces cerevisiae / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D013030:Spain; D014920:Wine / Q000382:microbiology*
chemical_list: D017931:DNA Primers