Microbial biogeography of wine grapes is conditioned by cultivar, vintage, and climate

TLDR

Wine grapes exhibit a unique biogeographic pattern of microbial biodiversity that influences quality, consumer acceptance, and economic value, yet the determinants of regional characteristics remain unclear and are often attributed solely to viticultural or geological factors. The study aims to show that regional, site‑specific, and grape‑variety factors shape the fungal and bacterial communities on wine‑grape surfaces. High‑throughput short‑amplicon sequencing was employed to profile the fungal and bacterial consortia on grape surfaces. Microbial assemblages were found to correlate with climatic features, indicating that regional climate and site factors create a nonrandom “microbial terroir” that shapes wine fermentation inputs.

Abstract

Wine grapes present a unique biogeography model, wherein microbial biodiversity patterns across viticultural zones not only answer questions of dispersal and community maintenance, they are also an inherent component of the quality, consumer acceptance, and economic appreciation of a culturally important food product. On their journey from the vineyard to the wine bottle, grapes are transformed to wine through microbial activity, with indisputable consequences for wine quality parameters. Wine grapes harbor a wide range of microbes originating from the surrounding environment, many of which are recognized for their role in grapevine health and wine quality. However, determinants of regional wine characteristics have not been identified, but are frequently assumed to stem from viticultural or geological factors alone. This study used a high-throughput, short-amplicon sequencing approach to demonstrate that regional, site-specific, and grape-variety factors shape the fungal and bacterial consortia inhabiting wine-grape surfaces. Furthermore, these microbial assemblages are correlated to specific climatic features, suggesting a link between vineyard environmental conditions and microbial inhabitation patterns. Taken together, these factors shape the unique microbial inputs to regional wine fermentations, posing the existence of nonrandom "microbial terroir" as a determining factor in regional variation among wine grapes.