Effects of low environmental manganese concentrations on the respiratory chains of Paracoccus denitrificans

Paracoccus denitrificans was cultivated in continuous culture in media deficient in manganese, or copper or both metals and the effects on growth and the respiratory chains studied. Manganese deficiency had no effect on growth yield or the levels of cytochrome c oxidase but the amount of c-type cytochromes was decreased to about 35% of control values and a CO-binding b-type cytochrome was also produced. However, the major functioning oxidase was still cytochrome c oxidase. The ESR and optical signals of copper were present or absent if cells were grown in the presence or absence of copper respectively, independent of the concentration of manganese available. This allows the ESR properties of the native and copper-deficient cytochrome c oxidase to be studied as the spectra are now not obscured by signals from manganese.