STUDIES ON A SOIL ACHROMOBACTER WHICH DEGRADES 2,4-DICHLOROPHENOXYACETIC ACID

Abstract

Cells of an Achromobacter sp. possess what appears to be an adaptive system that is capable of oxidizing 2,4-dichlorophenoxyacetic acid (2,4-D). The 2,4-D oxidizing system was most active at 30 °C. at pH 6.0 or lower, and in barbital buffer. The organism can oxidize a wide variety of 2,4-D analogues, and 2,4-dichloroplienol without prior adaptation, making analysis of mechanisms difficult. For rates of oxidation comparable with that of 2,4-D the organism appeared to have the following structural requirements: a free ortho position and, more important, an unchlorinated ortho position; a free carboxyl group on the side chain preferably β to the ethereal linkage; a chlorine atom in the para position and no more than two chlorine atoms in the ring whether or not an ortho position is free. Proposed and established pathways for the degradation of 2,4-D are presented and a possible new pathway involving 2,4-dichloroanisole is suggested.