Hexitol metabolism in Escherichia coli

D-Sorbitol and dulcitol (galactitol), which, to-gether with D-mannitol, are the three naturally occurring hexitols, have been known since the last quarter of the nineteenth century. Many fungi can utilize sorbitol for growth, but dulcitol is assimilated poorly by Aspergillus niger and a few yeasts. Among bacterial fermen-tations of these hexitols the best known are those by members of the Acetobacter group. These species will readily oxidize mannitol to fructose, sorbitol to sorbose, glycerol to dihy-droxyacetone, and erythritol to L-erythrulose, but most of the organisms will not attack dulcitol. In a study of oxidation by Acetobacter suboxydans, King and Cheldelin (1952) found that the initial step of sorbitol oxidation (1 atom of oxygen) in resting cells was not affected by 4 X 10-4 M 2,4-dinitrophenol, and thus they concluded that this step to sorbose was independent of the esterifica-tion of inorganic phosphate. Closely related to Acetobacter organisms are the pseudomonads studied by Sebek and Randles (1952). Only one strain of Pseudomonas fltores-cens grew on sorbitol; none of the seven strains showed growth on dulcitol. As growth on the hexitols was adaptive, the nature of their oxi-dation products could be studied by the tech-nique of "simultaneous adaptation " as well as by actual isolation. The former indicated fructose to be the product of sorbitol oxidation, while I Contribution No. 111 from the McCollum-Pratt Institute. The data in this paper are take