Yeast population dynamics in spontaneous fermentations: Comparison betweentwo different wine-producing areas over a period of three years

Yeast ecology, biogeography and biodiversity are important and interesting topics of research. The population dynamics of yeasts in several cellars of two Spanish wine-producing regions was analysed for three consecutive year s (1996 to 1998). No yeast starter cultures had been used in these wineries which therefore provided an ideal winemaking environment to investigate th e dynamics of grape-related indigenous yeast populations. Non-Saccharomyces yeast species were identified by RFLPs of their rDNA, while Saccharomyces species and strains were identified by RFLPs of their mtDNA. This study con firmed the findings of other reports that non-Saccharomyces species were li mited to the early stages of fermentation whilst Saccharomyces dominated to wards the end of the alcoholic fermentation. However, significant differenc es were found with previous studies, such as the survival of non- Saccharom yces species in stages with high alcohol content and a large variability of Saccharomyces strains (a total of 112, all of them identified as Saccharom yces cerevisiae) with no clear predominance of any strain throughout all th e fermentation, probably related to the absence of killer phenotype and lac k of previous inoculation with commercial strains.