The alcoholic fermentation of glucose by Moniliformis dubius (Acanthocephala), in vitro

Abstract

Adult Moniliformis dubius, obtained from freshly killed rats, were incubated in Tyrode's saline containing known amounts of D-[U-$^{14}$C]glucose under nitrogen or air. The worms appeared to remain in a healthy condition throughout the incubations which lasted for as long as 2$\cdot $5 h. Nearly all the radioactivity was recovered either within the worms or in the incubation vessel in the form of CO$_{2}$, excretory products and unmetabolized glucose. For incubations in nitrogen of 2$\cdot $5 h, about 95% of the original glucose was utilized and about 60% of this was excreted into solution or as CO$_{2}$. Under anaerobic and aerobic conditions, most of the carbohydrate catabolized was recovered as ethanol and CO$_{2}$, the end products of alcoholic fermentation. Small amounts were catabolized to lactate, succinate, acetate and butyrate. During the anaerobic incubations for 2$\cdot $5 h, nearly half the added glucose utilized by the worms was converted to ethanol and CO$_{2}$ and about one ethanol molecule in four was derived from this glucose. The radioactivity recovered as ethanol was twice that recovered as CO$_{2}$. About 97% of the radioactivity excreted into solution was present as ethanol and lactate in the ratio of approximately 6 molecules of ethanol to one of lactate. The remaining radioactivity was associated with succinate, acetate and butyrate. These results are compared with those obtained by other workers on M. dubius and other acanthocephalan worms. An important function for the excreted ethanol is postulated and the effect of this demonstration of alcoholic fermentation on contemporary concepts on the carbohydrate metabolism of intestinal helminths is discussed.