The genus of yeast which are particularly adapted to fermentation of strong sugar solutions and which thus produce high levels of alcohol. Saccharomyces cereisiae is the traditional brewing yeast and produces the typical flavour balance characteristic of beer. Other Saccharomyces yeasts also ferment but produce high levels of other flavours such as the spicy 4-vinyl guaiacol or the butterscotch diacetyl which are not so desirable. These Saccharomyces yeasts would be considered contaminants and may be termed wild yeasts. Saccharomyces diastaticus is a particularly undesirable contaminant in that it has the ability to ferment dextrins by producing amylase enzymes. As a result the beer becomes over fermented and lacks the body provided by the unfermentable sugars.