FIG. 3.

Three routes for 3-chlorobenzoate dehalogenation. (A) Reductive dechlorination of 3-chlorobenzoate as it occurs in D. tiedjei (18). 3-Chlorobenzoate is the terminal electron acceptor in halorespiration, and thus benzoate is the final product of the reaction sequence. (B) A proposed reaction series for 3-chlorobenzoate degradation that has not been observed but is analogous to the 4-chlorobenzoate utilization pathway of several species of aerobic bacteria (5). The free aromatic acid that is formed following dechlorination is degraded to tricarboxylic acid cycle intermediates by means of oxygen-requiring pathways for aromatic compound utilization. (C) Formation of 3-chlorobenzoyl–CoA followed by reductive dechlorination to form benzoyl-CoA as proposed here for R. palustris. Benzoyl-CoA is further metabolized to acetyl-CoA and carbon dioxide.