Susceptibility of the cell walls of some yeasts to lysis by enzymes of Helix pomatia

Abstract

Cells of Torulopsis glabrata, Candida albicans, and Saccharomyces cerevisiae were assayed during different phases of their growth cycles to compare their susceptibility to the action of helicase, an extract from Helix pomatia. Substantial differences were found in their reaction to the enzymes. The susceptibility of T. glabrata to muralysis disappeared completely within 2 h during the transition from exponential to stationary phase of growth, while in C. albicans and S. cerevisiae susceptibility diminished gradually during the stationary phase. It is postulated that such alterations in susceptibility are due to changes in the chemical composition of the wall concomitant with depletion of metabolites in the medium. Such changes could involve increases in the wall phosphomannan content or possibly a more extensive cross-linking of existing glucan and mannan polymers in the wall.Loss of walls, changes in volume, and the general appearance of these yeasts during treatment were followed by dark-field and phase-contrast microscopy, as well as by thin-section electron micrography.