Oxygen inhibition of the photoassimilation of CO2 in Rhodopseudomonas capsulata

The photoassimilation of ¹⁴CO₂ by washed cells of the photosynthetic bacterium Rhodopseudomonas capsulata was greatly inhibited in air. The inhibition was partially reversed by either sparging with argon or by adding inhibitors, e.g. CO [50% (v/v) in air] and NaN₃ (0.2 mM), which at these concentrations effectively restricted respiration. The effect of oxygen on the photoassimilation of ¹⁴CO₂ may be associated with a change in the redox state of the cells resulting in less reducing equivalents being available for this process.