The properties of a system for octanoate transport in Pseudomonas oleovarans are described. Transport is inducible and energy dependent, shows saturation kinetics, and concentrates against a gradient. Optimal transport is at pH 6.0 and 28 C. Apparent K(m) and V(max) values are, respectively, 7.0 muM octanoate and 0.68 nmol of octanoate transported per min per mg (dry mass) of cells. Fatty acids from C(7) to C(12) are competitive inhibitors, whereas alkanes, alkenes, and esters of the same carbon chain lengths show no inhibition. The K(i) values for heptanoate, nonanoate, decanoate, undecanoate, and dodecanoate are 17, 3.4, 3.2, 1.2, and 2.4 muM, respectively. The molecular specificity of this transport system is a linear hydrocarbon chain of no less than 6 to at least 11 carbon atoms and a carboxyl group.