Changes in cytochrome content and electron transport patterns in Pseudomonas putida as a function of growth phase

Optical absorbance difference spectra of membrane vesicles prepared from aerobically grown Pseudomonas putida indicated that, when harvested in logarithmic phase, the cells contained one c-type cytochrome and two or three b-type cytochromes, one of which was cytochrome o. As the cells grew into stationary phase and the oxygen concentration of the medium dropped to essentially zero, an additional component believed to be cytochrome d was produced. Both the o- and d-type cytochromes might function as terminal oxidases. No a-type cytochromes could be detected at any stage of growth. Polarographic measurement of oxygen utilization revealed that cyanide and azide are effective inhibitors of the oxidation of ascorbate coupled with 2,6-dichlorophenolindophenol or N,N,N',N'-tetramethyl-p-phenylenediamine in respiratory particles from either log-phase or stationary-phase cells. Reduced nicotinamide adenine dinucleotide- or succinate-dependent oxygen utilization, however, was sensitive to these inhibitors only in log-phase particles. These results indicate that an alternate terminal oxidase may be synthesized by this organism in response to restricted oxygen availability and that branching of the respiratory system may result.