Reversible Photo-oxidation of a Cytochrome Pigment in Photosynthesizing Rhodospirillum rubrum

Abstract

THE investigation reported here is a continuation of experiments¹ on reversible changes in light absorption in purple bacteria induced by irradiation. It presents evidence which indicates that, in living bacteria in the absence of oxygen and in the presence of substrate, a cytochrome pigment is oxidized by illumination and is reduced in the dark. The bacteria used were vigorously growing, one or two days old, Rhodospirillum rubrum, strains 1 and 4. The growth medium for strain 1 was tap-water containing 1 per cent peptone, and for strain 4 tap-water with 1 per cent peptone and 0.5 per cent sodium chloride.