Formate-Dependent Acetogenic Utilization of Glucose by the Fecal Acetogen Clostridium bovifaecis

Abstract

The acetyl-CoA pathway is an ancient pathway of CO 2 fixation, which converts 2 mol of CO 2 into acetyl-CoA. Autotrophic growth with H 2 and CO 2 via the acetyl-CoA pathway as the terminal electron accepting process is the most unique feature of acetogenic bacteria. However, the fecal acetogen Clostridium bovifaecis strain BXX displayed poor metabolic capabilities of autotrophic acetogenesis, and acetogenic utilization of glucose occurred only with the supplementation of formate. The formate-dependent acetogenic growth of Clostridium bovifaecis was associated with its lack of a gene encoding formate dehydrogenase, which may result from adaption to a formate-rich intestinal environment. This study gave insight into a unique metabolic feature of fecal acetogens. Because of the requirement of formate for the acetogenic growth of certain acetogens, the ecological impact of acetogens could be more complex and important in the formate-rich environment due to their trophic interactions with other microbes.