Genetic data suggest that the oligotrophic freshwater bacterium Caulobacter crescentus metabolizes D-xylose through a pathway yielding -ketoglutarate, comparable to the recently described L-arabinose degradation pathway of Azospirillum brasilense. Enzymes of the C. crescentus pathway, including an NAD -dependent xylose dehydrogenase, are encoded in the xylose-inducible xylXABCD operon (CC0823-CC0819).