The Coupling of Phosphate Accumulation to Acid Production by a Non-growing Streptococcus

Abstract

S U M M A R YAccumulation of phosphate by washed, stored suspensions of stationary phase streptococcal strain SL-I is strictly energy-dependent, essentially unidirectional and coupled stoichiometrically to acid production. At saturating concentrations of extracellular glucose and phosphate, incubation at varying pH values alters the rates of phosphate accumulation and concomitant fermentation of glucose such that coupling remains intact. Extracellular pH, while not affecting the coupling of phosphate accumulation to acid production, determines the total capacity for accumulation of phosphate and consequently the point of uncoupling of these processes. The conditions of cell storage profoundly affect the pH dependency of phosphate accummulation. During phosphate accumulation, the intracellular o-P04 pool contracts by more than 50%. About half of the accumulated phosphate appears in a high molecular weight fraction (i.e. insoluble in cold HClOJ under conditions which contraindicate net nucleic acid synthesis, protein synthesis or the incorporation of exogenous glucose carbon into high molecular weight cell constituents. The data are consistent with the hypothesis that stationary phase streptococcus SL-I synthesizes inorganic polyphosphates.

The Effect of Sucrose Application Frequency and Basal Nutrient Conditions on the Calcium and Phosphate Content of Experimental Dental Plaque

“…Inorganic phosphate has often been thought to be lost from plaque partly by uptake by microorganisms in metabolic phosphorylation reactions [Luoma, 1964;Tanzer et al, 1969]. While Dawes and Jenkins [1962] claimed that a sugar rinse decreases plaque P i , Tatevossian [1987] and Tatevossian and Jenkins [1969] were unable to consistently confirm this finding.…”

“…The effect of sugar on the inorganic orthophosphate (P i ) content of plaque is not so clear [Tatevossian et al, 1975;Ashley and Wilson, 1977a]. P i is taken up by fermenting cells and used in sug-ar phosphorylation and other anabolic processes [Luoma, 1964;Tanzer et al, 1969] and organic phosphate content may be slightly higher in plaque after extensive sugar exposure [Wilson and Ashley, 1988].…”

Relation of Saliva and Plaque to Caries

“…Several investigators have noted the high uptake of phosphorus by cariogenic streptococci and the increase in uptake in the presence of sucrose. 85,86 Recently, Luoma87 showed that the source of the phosphorus could be tooth enamel. Bowden, Nash, and Speirs88 found that uptake of phosphorus was not only dependent on carbohydrate but on viability of the bacterial cells as well.…”

Effect of in situ plaque mineral supplementation on the state of saturation of plaque fluid during sugar‐induced acidogenesis

“…The rise in Ca 2z concentration in plaque¯uid when pH falls (4,5), possibly originating from cell wall-bound Ca (6) and/or plaque mineral deposits (7), would tend to counteract the effect of H z on apatite saturation. Phosphate and¯uoride levels in plaque¯uid, on the other hand, do not appear to change signi®cantly after sugar rinsing (8,9) and, while pHsensitive release mechanisms have been postulated (10,11), these effects may be more or less negated by simultaneous uptake by bacterial cells through metabolic phosphorylation reactions (12) and intracellular diffusion of HF (13).…”