Erythritol Metabolism by Propionibacterium pentosaceum

Randomly labeled erythritol-14C has been synthesized and incubated with fluoride-poisoned suspensions of dried cells of Propionibacterium pentosoceum. Therefrom labeled glycerol-d-P, glyceric acid-j-P, erythritol-l-P, ribose-5-P, xyhalose-5-P, glucose-6-P, fructosed-P, mannosed-P, fructose-1 ,6-di-P, and sedoheptulose-7-P were isolated. Erythritol-W-1-P accumulated more rapidly than did the other phosphates. Even under conditions in which its dephosphorylation is inhibited it was metabolized to the same products as was erythritol-14C. Also, ln short term experiments the addition of unlabeled L-erythritol-1 -P to cell preparations actively metabolizing erythritol-i4C reduced the amount of label normally found as glycerlc acid-3-P. This supports the view that in P. pentosaceum erythrltol metabolism proceeds via a series of phosphorylated intermediates, of which L-erythritol-1 -P is the primary member. L-Erythritol1-P can serve as hydrogen donor for the reduction of 2,6dichloroindophenol in cell-free extracts. Although the product of the oxidation was not isolated, indirect evidence suggests that it is L-erythrulose-1-P and that this compound is the next intermediate in the erythrltol fermentation. Labeling dilution experiments indicated that D-erythrose4-P is not a direct intermediate in the sequence. The formation of labeled formaldehyde in the reaction mixtures lends support to the view that L-erythrulose-l-P, formed from L-erythrltol-l-P, undergoes cleavage between the Ca and Cc positions to yield formaldehyde and dihydroxyace-