STUDIES ON REACTIONS RELATING TO CARBOHYDRATES AND POLYSACCHARIDES. XXXV. POLYSACCHARIDE SYNTHESIS BY THE ACTION OF ACETOBACTER XYLINUS ON CARBOHYDRATES AND RELATED COMPOUNDS

Abstract

The action of Acetobacter xylinus, when cultivated in nutrient solutions containing certain carbohydrates or polyhydric alcohols, in forming surface polysaccharide membranes has been confirmed. The nutrient substrate necessary for the effective synthesis of nitrogen and ash-free polysaccharides from such carbon compounds has been carefully determined, and the necessity for the presence of a small amount of ethyl alcohol definitely proved. This type of synthesis appears to be specific for this organism, in that only the hexoses, their anhydrides and compounds which presumably yield hexoses as a result of the bacterial action, give rise to polysaccharide formation. When the carbon compound used is not a free hexose, nor one apparently capable of conversion into a hexose, as in the case of pentoses such as arabinose and xylose, glycols, polyglycols and erythritol, no membrane formation takes place. On the other hand mannitol, which is known to undergo oxidation with the formation of fructose under the experimental conditions, gives rise to a high yield of a synthetic polysaccharide. Glycerol behaves similarly, due presumably to a primary oxidation to dihydroxy acetone and conversion of this to fructose, the latter then yielding the polysaccharide membrane. The introduction of a methyl group into glycerol and glucose, with the formation of α-methyl glycerol and α-methyl glucoside, respectively, inhibits polysaccharide formation. The product obtained from glucose was found to be very closely related to cellulose, if not identical with it (13). Galactose is much less reactive than glucose, while mannose appears to be relatively inactive with the strain of A. xylinus employed. The highest yield of the polysaccharide was obtained from fructose, a result presumably connected with the recognized fact that this bacterium forms little or no acid from this sugar.