CHANGES IN MEMBRANE ELECTRICAL PARAMETERS OF YEAST FOLLOWING CHEMICALTREATMENT FOR PROTOPLAST ISOLATION

The yeast strains Saccharomyces species and Candida tropicalis were us ed, In each case, the electrorotation spectra were recorded for normal untreated yeast cells, beta-mercaptoethanol-treated cells and isolate d protoplasts. In order to obtain realistic information on the passive electrical membrane parameters associated with each step of protoplas t isolation, a theoretical analysis of the simulated electrorotation s pectra for shelled ellipsoids was performed, As a consequence, the par ameters chosen for fitting of the experimental spectra were the electr ical conductivities of the cell compartments, the membrane permittivit y and the scaling factor, beta-Mercaptoethanol was found to have signi ficant action at the membrane level: (1) at high concentration (2%), s igma(m) was increased dramatically; (2) in mild incubation conditions (0.1%), sigma(m) was decreased slightly. Treatment with the enzyme com plex led to a decrease in internal conductivity, probably due to a los s of the ionic equilibrium balance.