Glucose uptake by the cellulolytic ruminal anaerobe Bacteroides succinogenes

Abstract

Glucose uptake by Bacteroides succinogenes S85 was measured under conditions that maintained anaerobiosis and osmotic stability. Uptake was inhibited by compounds which interfere with electron transport systems, maintenance of proton or metal ion gradients, or ATP synthesis. The most potent inhibitors were proton and metal ionophores. Oxygen strongly inhibited glucose uptake. Na+ and Li+, but not K+, stimulated glucose uptake. A variety of sugars, including alpha-methylglucoside, did not inhibit glucose uptake. Only cellobiose and 2-deoxy-D-glucose were inhibitory, but neither behaved as a competitive inhibitor. Metabolism of both sugars appeared to be responsible for the inhibition. Cells grown in cellobiose medium transported glucose at one-half the rate of glucose-grown cells. Spheroplasts transported glucose as well as whole cells, indicating glucose uptake is not dependent on a periplasmic glucose-binding protein. Differences in glucose uptake patterns were detected in cells harvested during the transition from the lag to the log phase of growth compared with cells obtained during the log phase. These differences were not due to different mechanisms for glucose uptake in the cell types. Based on the results of this study, B. succinogenes contains a highly specific, active transport system for glucose. Evidence of a phosphoenolpyruvate-glucose phosphotransferase system was not found.