| Abstract: | The study of glucose-induced proton fluxes in Saccharomyces cerevisiae NCYC 431 showed a decrease of proton net efflux by ethanol across the plasma membrane of energized cells. Furthermore a negative net proton efflux (an influx) occurred from a given ethanol concentration (between 1.3 and 1.5 M) whatever the experimental conditions used, thus allowing the definition of a nil-net exchange step where no net movement of protons across the plasma membrane could be observed. A new technique of ethanol tolerance determination in yeast based upon a correlation for the same ethanol concentration between both the collapse of the proton gradient and the growth cessation in cultures supplemented with ethanol after 8 h incubation was proposed. The defined method also showed a cumulated effect of temperature and ethanol on Saccharomyces cerevisiae NCYC 431. |
