The Fermentation of Trehalose by Yeasts and its Taxonomic Implications

Abstract

In the classification of yeasts it is customary to use an infusion of bakers'' yeast as the basal medium for fermentation tests. This extract frequently contains variable amounts of trehalose. A number of yeasts were observed to ferment yeast extract and trehalose. The fermentation of yeast extract is serious from a taxonomic point of view, since it gives the impression of positive fermentation of a sugar which actually may not be fermentable. Dilute yeast autolysate should be used as the basal fermentation medium since during autolysis trehalose is destroyed. Tests of yeasts representing 20 genera and 73 spp. suggest that the fermentation of trehalose is worthy of consideration in differentiating certain spp. of Candida and perhaps other yeasts.