D-Mannitol l-Phosphate Dehydrogenase and D-Sorbitol 6-Phosphate Dehydrogenase in Aerobacter aerogenes”

n-Mannitol has been used as a carbon source for the growth of many microorganisms. Some bacteria contain diphosphopyridine nucleotide-dependent dehydrogenases that will oxidize n-mannitol to n-fructose at the nonphosphorylated level (2-5). On the other hand, Wolff and Kaplan (6, 7) have reported the presence of a diphosphopyridine nucleotide-dependent n-mannitol l-phosphate dehydrogenase that oxidizes n-mannitol l-phosphate to n-fructose g-phosphate in certain strains of the coli-aerogenes group, Lactobacillus casei, Lactobacillus plantarum, Leuconostoc mesenteroides, and Saccharomyces cerevisiae. Marmur and Hotchkiss (8, 9) have also found n-mannitol l-phosphate dehydrogenase activity in transformable strains of Diplococcus pneumoniae, whereas we find the enzyme to be present in extracts of Bacillus subtilis. It is interesting to note that Baddiley et al. (10) have reported that Lactobacillus arabinosus contains substantial amounts of n-mannitol l-phosphate. The oxidation of n-sorbitol by some bacteria may also occur at the phosphorylated or nonphosphorylated level comparable to n-mannitol oxidation to yield n-fructose or n-fructose 6-phosphate (2, 6, 11, 12). n-Sorbitol is structurally related to n-mannitol, the 2 molecules merely differing in the spatial configuration around 1 carbon atom. Previous work (1,7, 11) has shown that extracts of Aerobacter aerogenes, ATCC 8724 contain specific DPN-dependent dehydrogenases which oxidize n-mannitol l-phosphate and n-sorbitol 6-phosphate to n-fructose 6-phosphate, as indicated by the following equation.