[Microbial breakdown of acid anilide fungicides (author's transl)].

o-Toluylanilide, 2.5-dimethylfuran-3-carboxanilide, 5.6-dihydro-2-methyl-1.4-oxathiine-3-carboxanilide and other acid anilides are systemic fungicides which act selectively on rusts and smuts. From garden soil a Nocardia sp. was isolated which can grow with acid anilide fungicides as the only source of carbon. From this Nocardia sp. it was possible to produce mutants which are blocked genetically at various steps of the breakdown pathway of these acid anilide fungicides. It was possible to follow the breakdown pathway with the aid of accumulates of the rough I strain and of the mutants as well as by growth and enzyme tests. Breakdown starts with hydrolytic splitting of the acid amide bond by an acylamidase. The acid components of the fungicides are accumulated in the medium; they do not affect the growth. The aniline component is oxidized to pyrocatechol by a dioxygenase. Methyl and chloro-derivatives of aniline which are formed in the soil due to the hydrolysis of herbicides and fungicides, are also converted into the respective pyrocatechol derivatives. By orthocleavage cis-cis muconic acid forms from pyrocatechol. This compound is metabolized into succinate and acetyl CoA via the beta ketoadipate pathway.