Efficiency of energy conversion by aerobic glucose metabolism in Aphancapsa 6714.

Efficiency of adenosine triphosphate (ATP) formation from glucose oxidation in Aphanocapsa 6714 was estimated by quantitative measurement of phosphorylated intermediary metabolites and glycogen (polyglucose) formed from (14)C-glucose. P/2e ratios based on oxygen uptake ranged from 2.62 to 3.08, whereas those based on (14)CO(2) evolution ranged from 1.66 to 1.72. The synthesis of glycogen, which is the dominant energy-consuming process in resting cells exposed to exogenous glucose, was almost totally inhibited under anaerobic conditions, and the cellular concentration of ATP decreased steadily. Thus, both net synthesis of ATP and the steady-state concentration of ATP are obligatorily linked to respiration in this heterotrophic unicellular blue-green alga.