On the rôle of the carotenoids in photosynthesis in Rhodospirillum rubrum

Abstract

The photosynthetic action spectrum of Rhodospirillum vubrum Esmarck strain 4 was determined. Some carotenoids were found capable of absorbing photosynthetically active light. Apparently, however, the main carotenoid, spirilloxanthin, does not participate in photosynthesis.

Maxima and minima of the action spectra of photosynthesis and of phototaxis were found to coincide. Thus the correctness of Manten's hypothesis concerning a direct connection betweenboth processes is strongly supported.

The carotenoid action seemed to be less pronounced in phototaxis than it is in photosynthesis. In the discussion a hypothetical explanation of this phenomenon has been given.