Biosynthesis of amino sugars by Pseudomonas saccharophila.

Pseudomonas saccharophila growing on specifically labeled glucose incorporated isotope into cell wall glucosamine and muramic acid with less than 5% randomization of carbons. Glucosamine contained isotope in both the 1 and 6 positions when cells were grown on either galactose-6-(14)C or gluconate-6-(14)C. With galactose-1-(14)C, only muramic acid was labeled. Specific activities of the carboxyl group of muramic acid obtained from the glucose-grown cells did not indicate whether the origin of the side chain of muramic acid is pyruvate or phosphoenolpyruvate. However, the high specific activity obtained from galactose-1-(14)C suggested that induced cells preferentially incorporate C-1 of galactose into the side chain of muramic acid. Addition of unlabeled glucosamine to growing cultures repressed incorporation of substrate isotope into glucosamine, but muramic acid contained activity in the lactyl side chain.