Di Liu, Pangzhen Zhang, Qinglin Chen, Jean-Luc Legras, Deli Chen, and Kate Howell*
*University of Melbourne, Building 194, Grattan Street, Parkville, Victoria 3010, Australia (khowell@unimelb.edu.au)

Microbial biogeography contributes to regional distinctiveness of agricultural products and is important to determine wine quality and marketing. To evaluate the microbial influence on wine characteristics, this study investigated the microbial biogeography of wine, the interplay between microbial patterns and affecting factors, and how these patterns drive wine quality and styles. Samples of soils, plant, grapes, must, and wine were collected in grapegrowing regions across Victoria, Australia. Genomic DNA was extracted for microbial diversity profiling of fungi and bacteria and gas chromatography-mass spectrometry was used to separate and identify volatile compounds in the headspace of wine. At a large scale (~400 km), we found that vineyard ecosystems are structured and distinguished by fungal communities, that the fungal microbiome is an important component of vineyard ecosystems, and that it correlates with regional distinctiveness of wine. Further studies considered a smaller scale of microbiota and investigated the changes in fungal community composition and diversity during the annual growth cycle of the grapevine. We found that fungal ecology is dependent on the grapevine habitat (root zone soil, root, leaf, flower, and grape) and plant developmental stage (flowering, fruit set, veraison, and harvest). We characterized the first core microbiota of grapevines that existed over space and time to drive seasonal community succession in the vineyard ecosystem. The influence of microbial biogeographic patterns decreased during wine fermentation as the fungal populations were dominated by Saccharomyces spp. yeasts. Further investigation of the strain diversity and dynamics of Saccharomyces cerevisiae showed that this yeast can shape geographic patterns at a small scale and determine wine characteristics within a single region. Our findings describe a comprehensive scenario of wine microbial biogeography, providing further evidence for microbial contributions to wine terroir and perspectives for maintaining microbial diversity to produce quality wine.

Funding Support: Wine Australia; University of Melbourne