Cell wall components of various species of yeasts

Abstract

Cell walls were obtained from three species of yeasts, Torulopsis aeris, Oospora suaveolens and Geotrichum lactis, and their components were analysed. The monosaccharide constituents found were glucose and mannose in T. aeris, and the same, plus galactose, in O. suaveolens and G. lactis. The only amino sugar in all three cases is glucosamine. An increase in total nitrogen and hexosamine was observed, together with a decrease in total sugars, as the morphological characteristics approached those of filamentous fungi. The mannan content of the wall of O. suaveolens was directly related to the age of the culture. Three polysaccharide-protein complexes were isolated from each species. Glucose, mannose and galactose were present in quantities which varied from fraction to fraction in each case, but not in the strict proportions which have been found by other authors. There is no qualitative difference to be observed in the amino acid content of each fraction, the twelve most common in protein being present. Our analyses do not suggest that these fractions represent, as such, structural units in the cell wall. Examination of one fraction revealed that the original form of the cell remains in some cases. In these cases a large amount of hexosamine was present, which suggests that the fraction concerned contains the chitin of the original cell wall.