Effect of Substrate Salinity on the Ability for Protein Synthesis in Pea Roots

Abstract

The contribution of the reductive pentose phosphate cycle to the photometabolism of carbon dioxide and to carbon metabolism in Rhodospirillum rubrum grown photoheterotrophically with l-malate as the carbon source is nil, unlike autotrophically grown R. rubrum. Glycolic acid appears to be the first stable product of CO₂ fixation in R. rubrum cultured photoheterotrophically on l-malate. The results obtained in ¹⁴CO₂ fixation experiments suggest that the photometabolism of CO₂ through glycolate into malate is a major pathway of CO₂ fixation in such cells. However, l-malate was a much more efficient precursor of phosphate esters, and of glutamic acid, than was carbon dioxide; l-malate is therefore, in this case, a far more important source of cell carbon than is carbon dioxide.