Grapevine treatment with bagasse vermicompost changes the microbiome of Albariño must and wine and improves wine quality

Abstract

Winemaking is a well-known process comprising several steps to produce must and wine. Grape marc is a byproduct of wine production that can be vermicomposted and used as organic fertiliser. Grape marc vermicompost has a richer and more stable microbiome than grape marc alone and when added to the soil of vineyards it can improve grape production and wine quality. We compared Albariño must and wine microbiotas from grapevines treated with vermicompost derived from Albariño grape marc and controls (standard fertilisation). We hypothesised that observed microbial changes are connected to improved organoleptic properties observed in fertilised must and wine. Treated Albariño vines showed increased grape production and the final wine showed improved organoleptic properties. Metataxonomic analyses of the 16S rRNA and ITS gene regions showed that the Albariño must and wine microbiome varied in their taxonomic composition. Must bacteriotas showed no significant (p < 0.05) variation in alpha or beta-diversity, while wine bacteriotas and must and wine mycobiotas showed significant differences in richness and evenness, as well as in microbial structure (beta-diversity) between treated and control grapevines. Must and wine bacteriotas also showed significant (p < 0.05) changes in their predicted metabolic pathways. Our study suggests that changes in the abundance of specific bacterial and fungal taxa and the metabolic processes they carry out during Albariño winemaking can improve the productivity of the grapevine and the organoleptic properties of the wine.