Abstract
Winemaking involves a microbial ecosystem where yeast diversity, shaped by terroir and winemaking conditions, determines wine characteristics. Understanding the microbial diversity of vineyards and spontaneous fermentation is crucial for explaining a winery's typical wine profile. Studying and inoculating indigenous strains make it possible to produce high quality wines, reflecting the production environment. This study analyzes the yeast species involved in 16 spontaneous fermentations (8 in 2022 and 8 in 2023) from grapes of four distinct vineyards under two sets of winemaking conditions. A total of 1100 yeast colonies were identified by MALDI-TOF and DNA sequencing techniques. Saccharomyces (S.) cerevisiae and Hanseniaspora uvarum were the most prevalent species, alongside significant populations of non-Saccharomyces yeasts such as Lachancea thermotolerans and Metchnikowia pulcherrima, which were the most abundant ones. Minor yeast species, including Aureobasidium pullulans, Starmerella bacillaris, Kazachstania servazzi, and other Hanseniaspora spp., were also detected. The results demonstrated that yeast diversity in spontaneous fermentations varied according to vineyard origin and winemaking conditions. Differences between the two vintages studied indicated that annual climatic conditions significantly influenced yeast diversity, especially among non-Saccharomyces species. This substantial diversity represents a valuable source of indigenous yeasts for preserving the typicity of a winery's wines under controlled conditions.