The transport of glucose, fructose, and mannitol by specifically induced cells of Pseudomonas aeruginosa was energy and temperature dependent, obeyed saturation kinetics, and was inducible. These properties were commensurate with active transport mediated by an enzyme-like carrier.Cells of P. aeruginosa were induced to active transport of glucose by growth on either glucose, fructose, or mannitol, but not on succinate. Active transport of fructose was induced by growth on either fructose or mannitol, but not on glucose; and active transport of mannitol was induced by growth on mannitol, but not on fructose or glucose. Facilitated diffusion was not detected via counterflow experiments by induced cells that had been poisoned by sodium azide plus iodoacetate. It was hypothesized that transport of sugars by P. aeruginosa occurred by active transport and by passive diffusion only.When induced cells were incubated with these sugars for 10 s and then extracted with hot water, either free sugar alone or, in the case of fructose or mannitol, free sugar plus fructose 6-phosphate were detected. These data were interpreted to indicate that carbohydrates were transported as free sugars by P. aeruginosa and were trapped intracellularly by phosphorylation.