Diversity and evolution of non-Saccharomyces yeast populations during wine fermentation: effect of grape ripeness and cold maceration.

We have evaluated the effect of grape maturity and cold maceration prior to fermentation on the yeast ecology during wine fermentation. Non-Saccharomyces strains were selectively isolated and identified using two rapid PCR techniques, namely enterobacterial repetitve intergenic consensus-PCR and PCR-intron splice sites, in various wine fermentation conditions. These identifications were further complemented and confirmed by restriction fragment length poymorphism and sequencing analysis of the 5.8S-ITS and D1/D2 ribosomal regions, respectively. Eleven species belonging to five genera were identified. Candida stellata, Hanseniaspora uvarum and Hanseniaspora osmophila were the dominant species, representing almost 90% of the isolates. Minor strains presented different species of the genera Candida, Issatchenkia, Zygoascus and Zygosaccharomyces. Selective isolation made it possible to isolate some species that were hardly related to the wine-making process, such as Issatchenkia hanoiensis, a new species that has only been described recently.