METABOLISM OF THE HERBICIDE 2,4-D BY A NOCARDIOIDES-SIMPLEX STRAIN

The ability of Nocardioides simplex strain 3E to grow on and decompose the herbicide 2,4-D (dichlorophenoxyacetic acid), was studied. The initial degradation products of the herbicide - 2,4-dichlorophenol (2,4-DCP) and 3,5-dichloropyrocatechol (3,5-DCPC) were identified. It is shown that further conversion of 3,5-DCPC takes place, not along the known catechol pathway, but through hydroxylation of the ring with the formation of 3,5-dichlorohydroxy hydroquinone. Activity of hydroxyhydroquinone-1,2-dioxygenase an enzyme catalyzing splitting of the aromatic ring, with unsubstituted and 6-chlorohydroxyhydroquinone, was found, although this does not rule out the possibility of splitting of the incompletely dechlorinated ring. A scheme of the initial stages of decomposition of the herbicide is suggested.