Studies on Oxidation and Reduction by Pneumococcus. Iii. Reduction of Methylene Blue by Sterile Extracts of Pneumococcus

The two preceding papers of this series have dealt with the phenomenon of peroxide formation by pneumococcus. The first of these studies (1) concerned itself with the conditions under which this compound is formed when air is admitted to cultures of pneumococci which have been grown anaerobically. Under these conditions peroxide is formed at reactions and at temperatures inhibiting active cell multiplication. These facts suggest that the mechanism of peroxide production is dependent upon an interaction of oxygen and cell constituents, and that under experimental conditions, at least, this reaction may proceed independently of cell growth. This view is further supported by the data presented in the second paper (2) on the formation of peroxide by sterile extracts of pneumococci. The fact that soluble extracts of pneumococcus cells form peroxide when exposed to molecular oxygen is convincing evidence that this function is not dependent upon the presence of living, formed cells. Just as the admission of air to sterile pneumococcus extracts was found to give rise to the prompt formation of peroxide, so in the present experiments it will be shown that the addition of methylene blue to these same extracts results in rapid reduction of the dye to its colorless base. The admission of air or the addition of dye to pneumococcus extracts, in the absence of living cells, induces reactions which although yielding dissimilar products, may be alike in nature, depending upon whether molecular oxygen or methylene blue serves as hydrogen acceptor.