KINETICS OF PHOSPHATE TRANSPORT BY SYNECHOCOCCUS LEOPOLIENSIS (CYANOPHYTA): EVIDENCE FOR DIFFUSION LIMITATION OF PHOSPHATE UPTAKE1

The kinetics of phosphate transport by Synechococcus leopoliensis (Racih.) Komarek was investigated. Deviations from Michaelis-Menten kinetics were observed at law concentrations of phosphate and the deviations were consistent with diffusion limitation of transport. Activation energy analysis of the transport process at two concentrations, one at carrier saturation and the other at zero added phosphate yielded activation energies of 11.9 and 5.6 kcal/mole respectively at 25° C. The first is consistent with an enzyme limited process and the second with diffusion limitation through the unstirred layer.