Production of D- and L-xylulose by mutants of Klebsiella pneumoniae and Erwinia uredovora.

D-Xylulose and L-xylulose were produced biologically by the oxidation of a corresponding pentitol. A Klebsiella pneumoniae mutant was constructed for the oxidation of D-arabitol to D-xylulose. This mutant constitutively synthesized the D-arabitol permease system and D-arabitol dehydrogenase but was unable to produce the D-xylulokinase of the D-arabitol pathway or the D-xylose isomerase and D-xylulokinase of the D-xylose pathway. An Erwinia uredovora mutant which constitutively synthesized a novel xylitol-4-dehydrogenase but could not synthesize L-xylulokinase was used for the oxidation of xylitol to L-xylulose. Washed cell suspensions of either mutant incubated with 0.5% pentitol would oxidize 60 to 65% of the pentitol to the corresponding ketopentose in 18 h and excrete the ketopentose into the medium. Ketopentoses were rapidly purified from the remaining pentitol by hydroxyl affinity chromatography.