Growth of a mutant of Escherichia coli K-12 on xylitol by recruiting enzymes for -xylose and 1,2-propanedol metabolism

Wild type Escherichia coli K-12 cannot grow on xylitol and we have been unsuccessful in isolating a mutant directly which had acquired this new growth ability. However, a mutant had been selected previously for growth on -1,2-propanediol as the sole source of carbon and energy. This mutant constitutively synthesized a propanediol dehydrogenase. Recently, we have found that this dehydrogenase fortuitously converted xylitol to -xylose which could normally be metabolized by E. coli K-12. In addition, it was also discovered that the -xylose permease fortuitously transported xylitol into the cell. A second mutant was thus isolated from the -1,2-propanediol-growing mutant that was constitutive for enzymes of the -xylose pathway. This mutant could indeed grow on xylitol as the sole source of carbon and energy, by utilizing the enzymes normally involved in -xylose and -1,2-propanediol metabolism.