CARBOHYDRATE METABOLISM OF PULLULARIA PULLULANS

Abstract

Pullularia pullulans, ATCC No. 11942, has constitutive enzymes for the utilization of galactose, glucose, maltose, mannose, raffinose, sucrose, and trehalose, but not for lactose. The organism oxidized mannose more rapidly, and maltose and raffinose more slowly, than any of the other sugars. Moreover, it utilized galactose and glucose at approximately the same rate, but more rapidly than trehalose; the oxidation of sucrose, however, was very slow at first and then very rapid. When resting cells were incubated with glucose-1-C14, the carbon dioxide immediately produced was highly radioactive; when glucose-6-C14 was used, however, a considerable time elapsed before the production of noticeable amounts of radioactive carbon dioxide. The ratio of the activity of the carbon dioxide produced from glucose-1-C14 to that produced from glucose-6-C14 was greater in young cells than in old. The results indicated that resting cells catabolize glucose in such a manner that most of the carbon dioxide comes from carbon 1 of glucose. Extracts from cells were found to have an active phosphoglucomutase, glucose-6-phosphate dehydrogenase, 3-phosphoglyceraldehyde dehydrogenase, and fructose diphosphate aldolase. Both dehydrogenases were TPN-linked. The extracts also oxidized ribose-5-phosphate but not ribose. The organism has enzymes, therefore, to catabolize glucose by some of the reactions of the Embden–Meyerhof system as well as by those of the pentose phosphate cycle.