A microbial overview of Txakoli wine: the case of three appellations of origin

Igor Baroja-Careaga¹, Elena García de la Peña², Andone Estonba¹, Dario Cantu³, Iratxe Zarraonaindia^1,4
1 Department of Genetics, Physical Anthropology and Animal Physiology, University of the Basque Country, Leioa, Spain
2 Ardoatek, Camillo Villabaso, Bilbao, Vizcaya, Spain
3 Department of Viticulture & Enology, University of California, Davis, CA, USA
4 IKERBASQUE, Basque Foundation for Science, Bilbao, Spain

Email contact: igor.baroja@ehu.eus

The Txakoli, a white wine produced in the Basque Country (North of Spain), has recently gained popularity due to wine quality improvement and increase in both acreages of production and wine consumption. The aim of this study was to characterize the chemical and microbiological differences between Txakoli wines made with grapes from different sites.  Our analysis included Txakoli vineyards from three appellations of origin: Bizkaiko, Getariako, and Arabako Txakolina D.O.

 To describe the microbial composition, we sequenced using next generation sequencing the v4 domain of the 16S rRNA gene from 41 vineyard soils and grapes collected in 2016 and 2017. Metadata information (slope, orientation, soil edaphic properties, grape physical factors, etc.) was also collected and used to identify the potential environmental and factors responsible for the differences in the microbial composition of soils and grapes.

Soil pH significantly associated with differences in soil bacterial composition, grouping the 41 vineyards into 5 clusters, regardless of vintage or appellation. The historical land usage of the properties was found to be also a significant factor determining soil bacterial composition. Interestingly, the bacterial composition of grape berries significantly depended on rootstock type, supporting a strong influence of the rootstock genotype on the fruit-microbial associations. When removing rootstock as a factor, sugar content and pH significantly correlated with microbial composition differences between sites, revealing grape maturity as an additional important factor that drives microbial associations in the fruit.