Isolation and Identification of the Indigenous Yeast Population during Spontaneous Fermentation of Isabella ( Vitis labrusca L.) Grape Must

Grape must harbors a complex community of yeast species responsible for spontaneous alcoholic fermentation. Although there are detailed studies on the microbiota of L. grapes, less is known about the diversity and behavior of yeast communities present on fermenting grape must from other species of . In this work, we used a culture-dependent method to study the identity and dynamics of the indigenous yeast population present during the spontaneous fermentation of Isabella ( L.) grape must. Alcoholic fermentation was conducted using standard enological practices, and the associated non- and yeast community was analyzed using selective growth media and 5.8-ITS DNA sequencing. (synonym ), , and were the main non- species identified on Isabella fermenting must. , a yeast species rarely found on L. grapes, was also recognized on Isabella grape must. and , identified in this work on Isabella fermenting must, have not previously been found on L. grape must. Interestingly, and have recently been isolated from the surface of L. grapes from vineyards in the Azores archipelago, suggesting that specific -yeast species associations are formed independently of geographic origin. We suggest that , and are yeast species preferentially associated with L. grapes. Specific biological interactions between grapevines and yeast species may underlie the assembly of differential -microbial communities.