Genetic characterization of commercial saccharomyces cerevisiae isolates recovered from vineyard environments

Abstract

One hundred isolates of the commercial S. cerevisiae strain Zymaflore VL1 were recovered from spontaneous fermentations carried out with grapes collected from vineyards located close to wineries in the Vinho Verde Wine Region (Portugal). Isolates were differentiated based on their mitochondrial DNA restriction patterns and the evaluation of genetic polymorphisms was carried out by microsatellite analysis, interdelta sequence typing and pulse field gel electrophoresis. Genetic patterns were compared to the ones obtained for 30 isolates of the original commercialized Zymaflore VL1 strain. Among the 100 recovered isolates we found a high percentage of chromosomal size variations, most evident for the smaller chromosomes III and VI. Complete loss of heterozygosity was observed for two isolates that also lost chromosomal heteromorphism; their growth and fermentative capacity in a synthetic must medium was also affected. Considerably higher number of variant patterns for interdelta sequence amplifications was obtained for grape-derived strains compared to the original VL1 isolates. Our data show that the permanence of strain VL1 in natural grapevine environments induced genetic changes that can be detected different fingerprinting methods. The observed genetic changes may reflect adaptive mechanisms to changed environmental conditions that yeast cells encounter during their permanence in nature.