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 in itial degradation products of the herbicide - 2,4-dichlorophenol (2,4- DCP) and 3,5-dichloropyrocatechol (3,5-DCPC) were identified. It is sh own that further conversion of 3,5-DCPC takes place, not along the kno wn catechol pathway, but through hydroxylation of the ring with the fo rmation of 3,5-dichlorohydroxy hydroquinone. Activity of hydroxyhydroq uinone-1,2-dioxygenase an enzyme catalyzing splitting of the aromatic ring, with unsubstituted and 6-chlorohydroxyhydroquinone, was found, a lthough this does not rule out the possibility of splitting of the inc ompletely dechlorinated ring. A scheme of the initial stages of decomp osition of the herbicide is suggested.