CO2-fixing Enzymes in Pseudomonas fluorescens

Abstract

P. fluorescens grown on glucose or glutamate at 1.degree. or 20.degree. C, or on acetate at 20.degree. C, as sole carbon sources, contained pyruvate carboxylase [EC 6.4.1.1] and phosphoenolpyruvate carboxylase [EC 4.1.1.31]. Pyruvate carboxylase was insensitive to acetyl-CoA and L-aspartate, and its level in cell-free extracts was markedly dependent on the C source for growth, the highest specific activity being attained in glucose-grown cells. Phosphoenolpyruvate carboxylase, although less dependent on the nature of the C source, showed its highest level in acetate-grown cells; the enzyme activity required acetyl-CoA and was strongly inhibited by L-aspartate. The microorganism also had a phosphoenolpyruvate carboxykinase [EC 4.1.1.32], which showed its highest specific activity in cells grown on acetate, and a NADP-linked malate enzyme, [malate dehydrogenase, EC 1.1.1.40], apparently repressed by acetate and showing its highest specific activity in glutamate-grown cells.