A study of the enhancement of glycolysis in human saliva

Abstract

The oxygen uptake and acid production of the salivary microorganisms is enhanced by addition of salivary supernatant. This enhancement was found to be primarily due to a stimulation of the use of the glucose added and not to the use of supernatant as a substrate in addition to the glucose. Under anaerobic conditions, addition of the salivary secretion alone gave a rate of acid production that was much too low to account for the enhancement observed when glucose was present. Under aerobic conditions, however, with a range of concentrations of salivary secretion, the secretion added as the only substrate gave rates of respiration that coincided exactly with the enhancement measured when glucose was present. Nevertheless, the increased uptake of glucose observed on enhancement of respiration showed that most of the increased respiration was due to the use of glucose and not the supernatant. It is postulated that utilization of glucose is stimulated by the provision of nutrients by the salivary supernatant. This permits growth and thus creates a requirement for more energy; this energy is produced by an increase in glucose catabolism. The salivary micro-organisms with supernatant present grew at the same rate both with and without glucose present. This finding supports the view that the rate of respiration obtained does not depend on the amount of substrate for respiration provided by the supernatant. When glucose is present, however, it is used by the microorganisms in preference to the substrate in the supernatant.