IMPACT OF ABIOTIC AND BIOTIC FACTORS ON BIOADHESION PROPERTIES OF BRETTANOMYCES BRUXELLENSIS

Abstract

Brettanomyces bruxellensis is an ubiquitous yeast associated with different fermentation media such as beer and kombucha, where its presence is beneficial to bring an aromatic typicity. However, it is a main spoilage yeast in wines, in which it produces volatile phenols responsible for organoleptic deviations causing significant economic losses (Chatonnet et al., 1992). Cellar and winery equipment’s are considered as the first source of contamination, during fermentation and wine ageing process (Connel et al., 2002). Indeed, it is possible to find B. bruxellensis in the air, on walls and floors of the cellars, on small materials, vats and barrels. Furthermore, specific strains are recurrently isolated in wines of certain wineries, thus showing the ability of the species to be resident in the cellar for long periods (Cibrario et al., 2019). Bioadhesion phenomena and biofilm formation are protective mechanisms that could explain the persistence of B. bruxellensis in the winery and recurrent wine contaminations. A subset of 17 B. bruxellensis strains, representative of the species genetic diversity and showing contrasting bioadhesion phenotypes, were selected to study the impact of pH and ethanol concentration on electronegativity (Zeta potential), hydrophobic character (MATS) and bioadhesion on stainless steel by confocal microscopy. The experimental design consisted in multi-strains and multi-species bioadhesions in order to observe potential interactions. Our results show that pH and ethanol concentrations do not impact the phenotypes but that the strains and genetic groups are the main factors explaining the variance suggesting the role of genetic mechanisms on bioadhesion properties. Regarding multispecies bioadhesion, a decrease in the bioadhesion of B. bruxellensis is observed in association with lactic acid and acetic acid bacteria. Multi-strains bioadhesion of B. bruxellensis show that the most bioadhesive strain is present in higher proportions during the first stages of the bioadhesive process comparing with other strains. This study provides new insights into the impact of environmental factors on B. bruxellensis lifestyles as bioadhesion in response to stressful environments, with major consequences on surface colonization in food industry and wine spoilage.