NADH-peroxidase activity and H2O2 decomposition in a peroxidogenic strain of Streptococcus durans.

Streptococcus durans S-76 can accumulate hydrogen peroxide to high concentrations under aerobic conditions when it is previously grown anaerobically. An NADH-peroxidase enzyme protects this bacterium from the bactericidal effect of H2O2. The relationship between oxygen uptake and H2O2 excretion into the medium has been investigated in cultures containing or lacking glucose under various conditions of incubation. The results obtained suggest that neither oxygen nor H2O2 regulate the cellular levels of NADH-peroxidase whose activity seems to be controlled exclusively by the availability of reduced NADH.