Occurrence of wine yeasts on grapes subjected to different pesticide treatments

As a contribution to the study and preservation of indigenous wine yeast po pulations, the A. A. initiated a programme of isolation and characterizatio n of yeast strains from grapes of the Italian region of Marche. During the 1996 vintage, grape samples were collected From three groups of vineyards d iffering in the pesticide treatments given, of the 279 yeasts isolated, thi rty-nine were assigned to the species Saccharomyces cerevisiae. The majorit y of the isolates and all thirty-nine 5. cerevisiae came from vineyards whi ch had not been treated with systemic pesticides, indicating that these pes ticides may exert a negative effect on the biodiversity of the grape microf lora, and in particular on the occurrence of S. cerevisiae on grapes. The t hirty-nine S. cerevisiae isolated were subjected to microfermentation trial s, in which ten of them showed promising Fermentative capabilities.