The Role of Hydrogen Peroxide in Environmental Adaptation of Oral Microbial Communities

Abstract

Oral streptococci are able to produce growth-inhibiting amounts of hydrogen peroxide (H2O2) as byproduct of aerobic metabolism. Several recent studies showed that the produced H2O2is not a simple byproduct of metabolism but functions in several aspects of oral bacterial biofilm ecology. First, the release of DNA from cells is closely associated to the production of H2O2inStreptococcus sanguinisandStreptococcus gordonii. Extracellular DNA is crucial for biofilm development and stabilization and can also serve as source for horizontal gene transfer between oral streptococci. Second, due to the growth inhibiting nature of H2O2, H2O2compatible species associate with the producers. H2O2production therefore might help in structuring the initial biofilm development. On the other hand, the oral environment harbors salivary peroxidases that are potent in H2O2scavenging. Therefore, the effects of biofilm intrinsic H2O2production might be locally confined. However, taking into account that 80% of initial oral biofilm constituents are streptococci, the influence of H2O2on biofilm development and environmental adaptation might be under appreciated in current research.