Studies on the Formation Ofd-Arabitol by Osmophilic Yeasts

The formation of D-arabitol by a strain of osmophilic yeast has been studied. Both D-ribulose and D-xylulose were good substrates for the respiration of yeast, but D-xylulose was a better growth substrate than D-ribulose and produced larger amounts of D-arabitol. The utilization of D-xylulose-5-C 14 by the yeast resulted in the production of D-arabitol having two-thirds of the radioactivity in carbon-1. Extracts of the yeast contain an enzyme system which reduces D-xylulose to arabitol in the presence of NADH. The enzymatic activity increases with decreasing pH to 4.5, but the activity is readily destroyed below pH 7. The data presented suggests that D-xylulose is a precursor in the formation of D-arabitol by the osmophilic yeast.