Metabolism of 14C-chlorobenzilate and 14C-chloropropylate by Rhodotorula gracilis.

Rhodotorula gracilis metabolizes Chlorobenzilate (ethyl 4,4'-dichlorobenzilate) and Chloropropylate (isopropyl 4,4'-dichlorobenzilate) to several metabolites in a basal medium supplemented by sucrose and by several intermediates of the citric acid cycle. Three identified metabolites resulting from the degradation of either acaricide, were 4,4'-dichlorobenzilic acid, 4,4'-dichlorobenzophenone, and carbon dioxide. Chlorobenzilate, i.e., ethyl ester of 4,4'-dichlorobenzilic acid, was more easily hydrolyzed than Chloropropylate, i.e., isopropyl ester of this acid, so that larger amounts of carbon dioxide and 4,4'-dichlorobenzophenone were obtained from Chlorobenzilate degradation. Regardless of acaricides used, longer incubation caused a higher accumulation of 4,4'-dichlorobenzophenone. The probable steps of the degradation pathway are: Chlorobenzilate (or Chloropropylate) --> 4,4'-dichlorobenzilic acid --> 4,4'-dichlorobenzophenone plus carbon dioxide. It appears that the decarboxylation of 4,4'-dichlorobenzilic acid to 4,4'-dichlorobenzophenone was hindered by alpha-ketoglutarate and enhanced by succinate.