Aerobic respiration of Streptococcus pyogenes and pneumococcus Type 1 are strongly inhibited by KCN, NaN3, and Na2S. The anaerobic glycolysis of glucose by pneumococcus is also inhibited by KCN and NaN3.

Streptococcus pyogenes, E. coli, pneumococcus Type 1, B. subtilis, B. proteus, and Staphylococcus aureus did not catalyze the oxygen uptake by p-phenylenediamine in the presence of added cytochrome c or in its absence. Yeast cells, B. subtilis, and B. pyocyaneus oxidized p-phenylenediamine to a dark purple meriquinoid substance in contrast to the other bacteria mentioned above.

Streptococcus pyogenes in contrast to pneumococcus Type 1 catalyzed the oxygen uptake by cysteine. Neither of these bacteria catalyzed the oxygen uptake by tyrosine, adrenaline, pyrocatechin, xanthine, and hypoxanthine.

Streptococcus pyogenes, pneumococcus Type 1, and E. coli, boiled and not boiled, gave positive peroxidative tests with benzidine showing the presence of hematin compounds.

The results discussed in the light of the interpretations offered by Keilin and Harpley show that Streptococcus pyogenes and pneumococcus Type 1 contain cyanide-sensitive respiratory systems which are different from the cytochrome c-cytochrome oxidase system.

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