Genotype-dependent sulphite tolerance of Australian Dekkera (Brettanomyces) bruxellensis wine isolates

Aims: The aim of this study was to determine sulphite tolerance for a large number of Dekkera bruxellensis isolates and evaluate the relationship between this phenotype and previously assigned genotype markers. Methods and Results: A published microplate-based method for evaluation of yeast growth in the presence of sulphite was benchmarked against culturability following sulphite treatment, for the D.bruxellensis type strain (CBS 74) and a reference wine isolate (AWRI 1499). This method was used to estimate maximal sulphite tolerance for 41 D.bruxellensis isolates, which was found to vary over a fivefold range. Significant differences in sulphite tolerance were observed when isolates were grouped according to previously assigned genotypes and ribotypes. Conclusions: Variable sulphite tolerance for the wine spoilage yeast D.bruxellensis can be linked to genotype markers. Significance and Impact of the Study: Strategies to minimize risk of wine spoilage by D.bruxellensis must take into account at least a threefold range in effective sulphite concentration that is dependent upon the genotype group(s) present. The isolates characterized in this study will be a useful resource for establishing the mechanisms conferring sulphite tolerance for this industrially important yeast species.