The pathway of breakdown of 2:4-dichloro- and 4-chloro-2-methyl-phenoxyacetic acid by bacteria.

SUMMARY: The metabolism of 2:4-dichlorophenoxyacetic acid and 4-chloro-2-methylphenoxyacetic acid by a strain of Flavobacterium peregrinum and an Achromobacter sp., respectively, has been studied. Bacteria from young cultures were more active than those from older ones in oxidizing these substrates. Evidence is presented that adapted organisms dissimilate 2:4-dichlorophenoxyacetic acid through 2:4-dichlorophenol and 4-chlorocatechol, and that 4-chloro-2-methylphenoxyacetic acid is dissimilated through 5-chloro-2-cresol. Bacteria grown on 2:4-dichlorophenoxyacetic acid do not oxidize any of the other five possible isomers, but can oxidize 2:4-dibromo-, 4-bromo-2-chloro-, 4-chloro-, and, to a small extent, 2-chlorophenoxyacetic acids.