Effect of salivary supernatant on the glycolytic activity of the bacteria in salivary sediment

Abstract

The salivary supernatant of the suspended salivary sediment (SSS) system stimulates the glycolytic activity of the sediment bacteria under aerobic conditions. Evidence for such glycolytic stimulation in the experiments carried out at low glucose concentration was a more rapid utilization of glucose and a more rapid rise and fall in the concentration of lactic acid. Although supernatant enhanced glycolysis, after a 4-hr incubation those sediment mixtures without supernatant contained more acid and showed a much larger decrease in the pH than those mixtures with supernatant. At high glucose concentration the amount of glucose catabolized and the amount of total acid formed were much greater in those mixtures containing supernatant. The decrease in pH, however, was approximately the same. The smaller pH fall with low glucose and the almost equal fall with high glucose indicate that in the presence of supernatant there is increased base formation counteracting the enhanced glycolysis. With low glucose concentrations, the extent of the pH fall was dependent upon the supernatant concentration, whereas at high glucose concentration it was not.