A study is made of the DOPA oxidase of 4 strains of P. aeruginosa with an electrophotometer. Regarding a glycerol broth of detected 3 or 5 days culture, DOPA oxidase is highest in the cultured fluid of the strains producing pyocyanin; rather in a slight degree in a supernate whose cells has been centrifuged.
The melanin producing strain shows little oxidation in the cultured fluid or in the supernate. Cultured of the white strain (no pigment producing strain) seems to inhibit oxidation as a whole but it demonstrates oxidation in the supernate. If strains grown on an agar medium are washed and added with DOPA solution, either the pyocyanin strains or the melanin strain function little; the cell suspension of the white strain reveals a considerable inhibition of oxidation at the initial stage.
