Contributions of Respiratory and Photosynthetic Pathways during Growth of a Facultative Photoautotrophic Cyanobacterium, Aphanocapsa 6714

Abstract

Growth parameters and photosynthetic capacities of cells of Aphanocapsa 6714 under various growth conditions were compared. No enzymic regulation of CO2/glucose assimilation takes place in this strain. Functioning of photodependent phosphorylating pathways turns off oxidative ATP synthesis. No efficient regulation of pigment synthesis exists in these cells. Most modulations of photosynthetic activities probably occur through structural modifications of the photosynthetic membranes (a small proportion of the pigments might appear as a nonintegrated pool in the cell and be sensitive to synthesis regulation). Photosystem II activity would be dependent on light intensity in a discontinuous way, the consequence of this property being the appearance of 2 successive exponential phases during phototrophic growth in adequate light conditions.