EFFECTS OF SOME POTENTIAL ELECTRON ACCEPTORS ON GLUCOSE AS A SOLE ENERGY SOURCE FOR THE GROWTH OF LACTOBACILLUS VACCINOSTERCUS

The growth of Lactobacillus vaccinostercus on hexose as a sole energy source varies from no growth to slow, poor growth. The poor growth of L. vaccinostercus on glucose as a sole energy source was extensively studied. It was demonstrated that potential electron acceptors, i.e., pyruvate, acetoin, and acetone are required for good growth on glucose medium. The products of hexose fermentation were constantly equimolar quantities of lactate, ethanol, and CO2 even in the presence of these potential electron acceptors; it seems that the latter are utilized for electron transfer of the anabolic reaction rather than that of the catabolic tion. Good growth on pentose or gluconate as a sole energy source was reacfound without these potential electron acceptors. Their reduction by NADH2 or NADPH2 was demonstrated in the cell-free extracts of L. vaccinostercus from glucose medium, but the cell-free extracts from a pentose medium either did not catalyze, or only slightly so, this reduction with the exception of pyruvate. NADP-dependent reduction activities of acetoin and acetone were especially highly induced by the addition of these substances to glucose medium. From these results, the slow and poor growth of L. vaccinostercus was presumed to be due to the distortion of electron transfer in the growing cell.