Formation of Hydrogen and Formate by Ruminococcus albus

AUTOR(ES)
RESUMO

Radioisotopic growth studies with specifically labeled 14C-glucose confirmed that Ruminococcus albus, strain 7, ferments glucose mainly by the Embden-Myerhof-Parnas pathway to acetate, ethanol, formate, CO2, H2, and an unidentified product. Cell suspensions and extracts converted pyruvate to acetate, H2, CO2, and a small amount of ethanol. Formate was not produced from pyruvate and was not degraded to H2 and CO2, indicating that formate was not an intermediate in the production of H2 and CO2 from pyruvate. Cell extract and 14C-glucose growth studies showed that the H2-producing pyruvate lyase reaction is the major route of H2 and CO2 production. An active pyruvate-14CO2 exchange reaction was demonstrable with cell extracts. The 14C-glucose growth studies indicated that formate, as well as CO2, arises from the 3 and 4 carbon positions of glucose. A formate-producing pyruvate lyase system was not demonstrable either by pyruvate-14C-formate exchange or by net formate formation from pyruvate. Growth studies with unlabeled glucose and labeled 14CO2 or 14C-formate suggest that formate arises from the 3 and 4 carbon positions of glucose by an irreversible reduction of CO2. The results of the studies on the time course of formate production showed that formate production is a late function of growth, and the rate of production, as well as the total amount produced, increases as the glucose concentration available to the organism increases.

ACESSO AO ARTIGO

Documentos Relacionados