E. coli K12 cannot grow on D arabitol, L arabitol, ribitol or xylitol. Using a mutant of E coli K12 (strain 3) that can grow on L 1,2 propanediol, a second stage mutant was isolated which can utilize D arabitol as sole source of carbon and energy for growth. D Arabitol is probably transported into the bacteria by the same system as that used for the transport of L 1,2 propanediol. The second stage mutant constitutively synthesizes a new dehydrogenase, which is not present in the parent strain 3. This enzyme, whose native substrate may be D galactose, apparently dehydrogenates D arabitol to D xylulose, and its structural gene is located at 68.5 ±1 min on the E coli genetic map. D Xylulose is subsequently catabolized by the enzymes of the D xylose metabolic pathway.
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