6533b7d3fe1ef96bd125fd5e

RESEARCH PRODUCT

Fungal biodiversity in a new winery and population dynamics in the winery (Saccharomyces cerevisiae) and in aging cellar (Brettanomyces bruxellensis)

subject

description

The interspecific fungal biodiversity (Illumina Mi-Seq) and the dynamics of Saccharomyces cerevisiae and Brettanomyces bruxellensis species were studied in a new winery and/or in 3 aging cellars, more specifically on the floor, the walls, the equipment and the outside of the barrels. In the new winery, an initial fungal consortium (yeasts and molds) is already present on all the winery environments before the arrival of the first harvest. This consortium consists of fungal genera such as Aureobasidium, Alternaria, Didymella and Filobasidium. These genera, that persist during two vintages, are not specific to the winery environment and seem to be adapted to natural or anthropic environments due to their ubiquitous character. The initial consortium is enriched by oenological genera (e.g. Hanseniaspora, Saccharomyces) that are introduced into the winery either by the harvest or by potential transfers between the different environments of the winery. However, these genera do not seem to persist or establish due to their low adaptation to the stressful conditions of the winery environment. The dynamics of wild S. cerevisiae in the new winery was also studied. No isolates belonging to this species were found before the arrival of the first harvest, confirming that this species is not specific to the winery environment and its presence is related to the alcoholic fermentation activity. However, the results obtained suggest a potential colonization of the new winery environment by certain S. cerevisiae strains. These so-called « colonizing » strains showed a higher capacity to form biofilms compared to non-implanted strains. This study highlights the importance of the winery environment that constitutes a true ecological niche for fungal populations capable of implantation during the winemaking process. In the environment of the 3 aging cellars, the equipment and the outside of the barrels (in direct contact with wine) are the environments that seem to be favorable for the development and installation of cultivable microbial populations (yeasts and lactic acid bacteria) and spoilage microorganisms (acetic acid bacteria and B. bruxellensis), unlike the floor and the walls where low microbial populations were found. Recurrent strains of B. bruxellensis have been found on both the equipment and the outside of the barrels and could be the cause of wine contamination during aging. These recurrent strains showed greater biofilm formation and resistance capacities which could explain the persistence of B. bruxellensis in aging cellars. These results highlight the importance of equipment cleaning and the regular monitoring of wines during aging in order to limit the contaminations.