Selective penetration of ammonia and alkylamines into Streptococcus fecalis and their effect of glycolysis

Abstract

Evidence was presented for the selective penetration of free base into Streptococcus fecalis cells suspended in solutions of NH4Cl, CH3NH3Cl, (CH3)2NH2Cl and (CH3)3NHCl at pH 7.0 or below. The selective penetration was measured by automatic continuous titration of the appearance of H+ and was found to be practically instantaneous. Selective penetration of NH3 was freely reversible and led to passive accumulation of NH4+. A mathematical equation was developed which satisfactorily describes the observed relation between amine uptake and extracellular amine concentration at constant pH. This equation permits an estimation of the intracellular pH and the rise in intracellular pH following penetration of free amine. Tentatively the intracellular pH of S. fecalis cells obtained from stationary growth phase is estimated to be about 5.0. Glycolysis in “aged” cells is retarded but is restored immediately following selective penetration of NH3 or alkylamines at constant extracellular pH. K+ and Na+ also restored glycolysis but their action was slower. K+ and Na+ were found to elicit an efflux of H+ at constant extracellular pH from non-glycolyzing cells possibly by ion exchange. It is concluded from these findings and a number of others as well that glycolysis in “aged” cells is inhibited by their low intracellular pH and is restored when the intracellular pH is raised.