COMPOSITION OF THE CELL-WALLS OF SEVERAL YEAST SPECIES

Cell walls, representing 26%-32% of the cell dry weight, were prepared from several strains of the yeasts Kloeckera apiculata, Debaryomyces hansenii, Zygosaccharomyces bailii, Kluyveromyces marxianus and Saccha romyces cerevisiae. Extraction of the walls with potassium hydroxide a t 4 degrees C, followed by saturation of the alkali-soluble extract wi th ammonium sulphate gave fractions of mannoprotein, alkali-soluble gl ucan and alkali-insoluble glucan. Chitin was associated with the alkal i-insoluble glucan. The proportions of the different fractions within the walls varied with the species and strain. Mannoprotein comprised b etween 25% and 34% of the walls, the content of alkali-insoluble gluca n ranged from 15% to 48%, and the content of alkali-soluble glucan ran ged from 10% to 48%. There was significant variation in the physical a ppearance of the alkali-soluble glucans and the relative viscosity of suspensions of these glucans. The yeasts could represent novel sources of polysaccharides with industrial and medical applications.