Yeasts

Wine is the end product of the fermentative activity of yeast and bacteria. The microbiota of grape juice fermentation can vary significantly as over 40 genera and 100 different species of yeast have been isolated from grapes or wine. Although the genera listed are commonly identified in surveys of grape mycobiota, some yeast species are more universally found than others, and numerous factors impact the composition of the yeast microbial community of grapes and their persistence during fermentation. Saccharomyces cerevisiae is the primary agent responsible for the conversion of grape sugars into alcohol but other yeast, collectively known as non-Saccharomyces yeast, and bacteria may also contribute to the aroma and flavor profile of the wine. Thus interspecies as well as intraspecies diversity plays an important role in the evolution of wine composition.