Biodiversity of Saccharomyces yeast strains from grape berries of wine-producing areas using starter commercial yeasts

Abstract

The use of commercial wine yeast strains as starters has been extensively generalised over the past two decades. In this study, a large scale sampling plan was devised over a period of three years in three different vineyards in the south of France, to evaluate autochthonous wine yeast biodiversity in vineyards around wineries where active dry yeasts have been used as fermentation starters during more than 5 years. 72 spontaneous fermentations were performed from a total of 106 grape samples, of which 2160 colonies were isolated. Among these, 608 Saccharomyces strains were identified and 104 different chromosomal patterns found. The large majority of these (91) were found as unique patterns, indicating a great biodiversity. This differed according to the vineyard and year, showing that biodiversity of Saccharomyces strains is influenced by climatic conditions and specific factors associated to the vineyards such as age or size. Strains that for their wider geographical distribution or perennial behaviour were terroir yeast candidates were not found. Biodiversity of S. cerevisiae strains after harvest was similar to that of the early campaign; this fact together with the differences in biodiversity level between the vineyards and the years studied, verifies that other factors were more important than commercial yeast utilisation in the biodiversity of the vineyard.