STUDIES ON OXIDATION AND REDUCTION BY PNEUMOCOCCUS : III. REDUCTION OF METHYLENE BLUE BY STERILE EXTRACTS OF PNEUMOCOCCUS.

1. Sterile broth extracts of unwashed pneumococci, entirely free from living or intact cells, actively reduce methylene blue. 2. Sterile extracts prepared by extracting washed pneumococci in phosphate solution are unable by themselves to reduce methylene blue. Upon the addition of meat infusion or yeast extract, these washed cell extracts actively reduce methylene blue. 3. The system or systems in pneumococcus extracts responsible for methylene blue reduction are destroyed by exposure to temperatures practically identical with those which have been previously found to destroy the peroxide-forming activity of the same extracts. 4. It is suggested that peroxide formation and methylene blue reduction by pneumococcus extracts are functions of the same or closely related systems, the particular reaction induced depending upon whether molecular oxygen or methylene blue serves as hydrogen acceptor or oxygen donator.