FIG. 1.

Illustration of the 2,4-D degradation pathway in R. eutropha JMP134, the archetype 2,4-D degrader (13). The catabolic genes tfdA, tfdB, and tfdC were originally discovered in strain JMP134 and encode a 2,4-D/2-oxoglutarate dioxygenase, a chlorophenol hydroxylase, and a chlorocatechol 1,2-dioxygenase, respectively (14, 33). Other tfd genes are involved in the further transformation to products of the tricarboxylic acid cycle (14).