PRODUCTION OF POLYHYDRIC ALCOHOLS BY OSMOPHILIC YEASTS

Abstract

Cultures of osmophilic yeasts were isolated from fermenting honey, brood comb pollen, flower parts, and other sources and tested for glycerol production. Most of the strains tested produced one or more of the sugar alcohols glycerol, erythritol, D-arabitol, and mannitol, in quantities varying with the strain of yeast and the conditions of growth. Study of factors affecting the production of glycerol and D-arabitol by one strain showed that yields were influenced by the nitrogen source and by the rate of aeration. Increasing the concentration of yeast extract in the medium increased the rate of glucose utilization, the ratio of glycerol to D-arabitol, and the actual yield of glycerol. Addition of small quantities of urea, ammonium sulphate, ammonium tartrate, or ammonium phosphate gave similar results, and urea had the greatest effect. More vigorous aeration reduced the rate of glucose utilization, reduced the yield of ethanol, and increased the yield of glycerol, without affecting the D-arabitol yield. As much as 60% of the glucose dissimilated was converted to polyhydric alcohols.