Direct utilization of maltose by Escherichia coli.

In the course of genetic studies, a mutant strain of Escherichia coli was developed which is characterized by rapid fermentation and oxidat,ion of maltose but not of glucose. Since this mutant offered an excellent opportunity to invest,igate the so called direct utilization of disaccharides (l), a study of the enzyme systems involved in maltose decomposition was undertaken. Experiments with dry cell preparations from the mutant strain led to the conclusion that maltose is initially transformed to polysaccharide and glucose. This reaction is followed by the phosphorolytic decomposition of the polysaccharide and the usual sequence of glycolytic steps. While the work was in progress, Monod and Torriani reported the discovery of a polysaccharide-forming enzyme in E. coli which they called ‘(amylomaltase” and described a method of separating it from other enzymes involved in fermentation (2). They showed that neither phosphate nor glucose-lphosphate is involved in the transformation of maltose to polysaccharide and that the enzyme is adaptive in nature, being formed only when maltose is used as substrate for the bacteria. They represent the action of “amylomaltase” on maltose by the following equation: