SELECTED NATIVE YEASTS

Two of the more troublesome yeasts that grow in juice and wine are Brettanomyces sp. and its sporulating ( perfect ) equivalent, Dekkera sp. Historically, the wine community has viewed Brettanomyces as producing frank 

Despite the traditionally negative connotations surrounding these yeasts, some winemakers question whether or not some Brett character is beneficial in certain styles of wine. In these cases, the organism is thought to play a positive role in flavor and bouquet complexity as well as imparting aged characters in the case of some young red wines. 

Unfortunately, much of what is known (or believed) about Brett, from the winemaker s point of view, is based on sensory changes occurring in the wine. In surprisingly few instances, are these observations supported by laboratory validation or conclusive identification of the organism (s) involved. 

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In addition to identifying protein partners, yeast two-hybrid technology can be used to identify and study in detail the interaction domains between two proteins. Here, bait and/or fish truncation or deletion constructs of the parent proteins are engineered and characterized as described earlier (see 3.1 Selection and characterization of bait constructs). These are then investigated for association in a yeast two-hybrid interaction assay. Once the BD has been identified, it can be further refined by mutagenesis. The same caveat applies to these studies as for the identification of associating proteins, i.e., it is assumed that the respective fusion proteins fold and adopt the same or a similar three-dimensional conformation to the native protein. This is not always the case and results should be interpreted with caution and if possible, always validated by an alternative experimental approach. O Table 19-1 shows an example of mapping the... 

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