The uptake of glucose and gluconate is under inductive control in Pseudomonas putida. Glucose, gluconate, and 2-ketogluconate were each good nutritional inducers of these transport abilities. Glucose and gluconate uptake obeyed saturation kinetics: the apparent Km for glucose was 6 mM and that for gluconate was 0.5 mM. Therefore, transport of both substrates appears to be mediated by enzyme-like carriers. Glucose and gluconate are parallel inhibitors for their uptake9 Strains selected for their inability totransport glucose were found to be deficient in gluconate uptake. The reverse was alsotrue: mutations affecting gluconate entry also blocked the uptake of glucose. These results demonstrate that a common carrier is involved in the uptake of both glucose and gluconate by P. putida cells.