On the mechanism of xylitol-dependent inhibition of glycolysis in streptococcus sobrinus OMZ 176

Abstract

1. 1. The mechanism of xylitol-dependent inhibition of glycolysis in Streptococcus sobrinus OMZ 176 was investigated in aerobically and anaerobically grown cells. 2. 2. Glucose-stimulated glycolysis was followed polarographically, by radio-HPLC-analyses of glycolytic intermediates, by measurement of ATP generated, and spectrophotometric monitoring of extent of NAD(P) +/NADPH-status. 3. 3. Xylitol added to suspensions of S. sobrinus inhibited O 2 uptake by approximately 20%, and led to a corresponding decrease in rate of lactate formation in aerobic and anaerobic cells. 4. 4. Xylitol also delayed the onset of the glucose-dependent rapid reduction of NAD(P) + by approximately 1 min, although the total extent of reduction was not significantly affected compared to control cells. 5. 5. The inhibitory effect of xylitol on glucose dependent ATP synthesis, however, was decreased by 70–80%. 6. 6. Hence the dramatic decrease in glucose-dependent synthesis of ATP may be the direct cause of decreased bacterial growth in the presence of xylitol. 7. 7. A mechanism explaining the observed phenomena is proposed.