The Metabolism of Acetate by the Blue-green Algae , Anabaena variabilis and Anacystis nidulans

The utilization of acetate by blue-green algae was examined and the activities of enzymes involved in its metabolism measured. Although acetate did not stimulate the endogenous respiration of these organisms, the oxidation of acetate was followed by the rate of release of [14C] carbon dioxide from [I-~~CC] and [2-l4CC] sodium acetate. Similarly, sodium acetate did not alter the rate of growth of Anabaenu variahilis and Anacystis nidulans but in A . variabilis it was found to contribute 7-2 "/b of the dry weight when cultures were gassed with air+CO, (95+5, vlv), and 16.9% when gassed with air alone. The presence of acetate in the growth medium did not alter the activity of the acetate-activating enzymes, glyoxylate cycle enzymes or two tricarboxylic acid cycle enzymes. The failure to show enzyme adaption by these organisms when supplied with an exogeneous substrate is discussed in relation to their hitherto apparently autotrophic nature.