FIG. 1.

Benzoyl-CoA degradation pathway in anaerobic bacteria. Benzoyl-CoA is reduced to cyclohexa-1,5-diene-1-carboxyl-CoA by an ATP-dependent (facultative anaerobes) or ATP-independent (obligate anaerobes) benzoyl-CoA reductase. Further reactions of the upper degradation pathway include a hydratase, dehydrogenases, and a ring-opening hydrolase. The lower pathway comprises modified β-oxidation reactions. In facultative anaerobes, glutaryl-CoA is dehydrogenated and decarboxylated to crotonyl-CoA by a single GDH; in some obligate anaerobes, these reactions are catalyzed by separated nondecarboxylating GDH and membrane-bound glutaconyl-CoA decarboxylase.