No abstract

Pichia membranifaciens strain FY-101, isolated from grape skins, was found to be antagonistic to Botrytis cinerea, the causal organism of the grey mould disease of the grapevine. When grown together on solid as well as liquid media, the yeast brings about the inhibition of this parasitic fungus, coagulation and leakage of its cytoplasm, and suppression of its ability to produce the characteristic grey mould symptoms on the grapevine plantlets. In vitro experiments confirm that this yeast can be used as a biological control organism against B. cinerea. An account of the molecular characterisation of P. membranifaciens (complete sequence of the ITS region of its ribosomal DNA, GenBank accession No. AF 270935), as well as the interaction between B. cinerea and the yeast, are given here.

Aims The yeast community structure associated with grapes is an essential part of the wine‐growing chain with a significant effect on wine quality. The aim of the present study was to evaluate the effect of the varietal factor on the yeast community assembly on grapes and during must fermentation. Methods and Results We analysed the wine yeast populations associated with four different grape varieties from the Greek national collection vineyard of Lykovryssi. The vintage effect was also considered by sampling the grapes for two consecutive years. Fourteen yeast species were recovered and genotyped to distinct subpopulations. A relatively stable yeast community structure was detected across vintages, with Hanseniaspora guilliermondii being the core species of the vineyard under study. The detected species subpopulations shared a relatively high genetic similarity with several genotypes persisting across vintages. Conclusions It was shown that different grape cultivars were associated with distinct yeast communities, pointing to their possible implication on wine chemical diversity. Significance and Impact of the Study Present findings show that the varietal factor is an important sharpener of the vineyard‐associated wine yeast community, which may interfere with the organoleptic profile of the resulting wines.