Oxygen uptake and H2O2 production by fermentative Mycoplasma spp.

Oxygen uptake and H2O2 accumulation during the metabolism of glucose and glycerol by whole cells, and of L-alpha-glycerophosphate (GP) and NADH by cells lysed with Triton, was determined for the type strains of six fermentative Mycoplasma species. Oxidation of glucose and of NADH by M. mycoides, M. pneumoniae and M. putrefaciens was accompanied by the accumulation of relatively small quantities of H2O2 (less than 0.05 mol/mol O2), though larger quantities (0.17-0.24 mol/mol O2) were produced by M. dispar. M. fermentans and M. canis were distinguished from the other strains used in that O2 uptake in the presence of glucose could not be demonstrated. However, metabolism of glucose was indicated by a reduction in the pH of the suspending medium and lysed cells oxidised NADH with the production of approximately 1.0 mol H2O2/mol O2 taken up. Glycerol was oxidised by all the strains studied except M. fermentans, and large quantities of H2O2 (0.48-1.07 mol/mol O2) accumulated. Cells of the glycerol-oxidising strains, lysed with Triton, oxidised GP with the production of approximately 1.0 mol H2O2/mol O2 utilised, which indicated the presence of a GP oxidase. The importance of H2O2 production as a factor in the pathogenicity of some mycoplasmas might depend upon the availability of glycerol in vivo.