Intracellular flux of glucose metabolism in streptococcal cells by simultaneous monitoring of fluorescence dependent on reduced nicotinamide adenine nucleotide and acid excretion under strictly anaerobic conditions

Reduced nicotinamide adenine nucleotide (NADH)-dependent fluorescence and a cid excretion during glucose pulse to washed Streptococcus mutans cells wer e monitored simultaneously at pH 7.0 with a fluorescence spectrophotometer and a pH-stat. Acid excretion started with addition of glucose. At the same time, the fluorescence dropped quickly to a minimum level and increased to a plateau level, suggesting that pyruvate metabolism started immediately a fter addition of glucose, then the rate of the pyruvate metabolism became a lmost equal to the rate of glycolysis. When the acid excretion stopped, the fluorescence increased rapidly from the plateau to the maximum level, sugg esting that the pyruvate metabolism stopped first, and then began to decrea se to the original level, The system used in this study for simultaneously monitoring the level of NADH and acid excretion gives us a crucial tool to clarify a biochemical mechanism of the control of sugar metabolism by strep tococci.