A comparison between Nitrosomas europaea and Thiobacillus novellus on the basis of their oxidation systems of inorganic compounds.

Nitrosomonas europaea and Thiobacillus novellus were compared with each other on the basis of the biochemical properties of their inorganic compound-oxidizing systems. Cytochromes c of the two organisms differ considerably from each other; N. europaea cytochrome c-552 belongs to the "bacterial-type" cytochrome c, while T. nouellus cytochrome c-550 resembles eucaryolic cytochrome c. The specificity of cytochrome oxidase for cytochrome c as the electron donor is different between the two organisms; T novellus oxidase reacts rapidly with cytochromes c of the organisms which seem to be higher than the organisms whose cytochromes c react rapidly with N. europaea oxidase. On the basis of these facts, N. europaea seems to be older organism than T. novellus in terms of evolution.