Characterization of Indigenous Microbial Communities in Vineyards Employing Different Agronomic Practices: The Importance of Trunk Bark as a Source of Microbial Biodiversity

Microbiomes are essential to viticulture and winemaking since various fungi and bacteria can exert positive and negative effects on grape health and wine quality. The current work evaluates the communities of culturable fungi and bacteria associated with Corvina vines derived from two vineyards from a similar terroir (within the Valpolicella DOC area, Italy) but on which different management practices were employed: organic and conventional farming. Samples of bark and grapes were collected in four spatial points for each vineyard. Populations of bark-associated microorganisms were monitored during ripening season (at veraison and at harvest time), and results were integrated with data from grape-associated microorganisms, sampled right before harvest. Culturable populations of fungi and bacteria were determined by plate counting on WL and PCA culture media. For fungi, biodiversity was also assayed on all samples through molecular methods, by ITS-RFLP analysis. Although this does not represent a comprehensive evaluation of the microbiome, since culturable and countable microorganisms only represent a portion of microbial biodiversity, our results emphasize the importance of vine trunk bark, not only as an interesting habitat to be characterized for monitoring microbial biodiversity in vineyards but also as a potential source of microbial viable species for further isolation.