CHARACTERIZATION OF MEMBRANE-BOUND ATPASE ACTIVITY OF LEUCONOSTOC-OENOS - GROWTH-CONDITIONS

A protocol for Leuconostoc oenos plasma membrane isolation, which was improved for studying lipidic and proteic constitution according to gr owth conditions, allowed us to determine some kinetic properties of me mbrane-bound ATPase activity: optimum pH, 5.6; the Michaelis constant (K-m) for ATP, 1.1 mM; Mg2+-dependence. L. oenos membrane-bound ATPase activity was regulated according to cell growth phase, growth medium and extracellular conditions. The regulation mode of this activity was not investigated but it was very rapid: differences in level of activ ity were observed in less than Ih when extracellular pH was modified o r when ethanol was added. Wine induced a large decrease in ATPase acti vity of L. oenos. This may explain the loss of cell viability after di rect inoculation into wine, when malolactic fermentation was not spont aneously obtained.