MINERALIZATION OF 3-PHENOXYBENZOATE BY A 2-MEMBERED BACTERIAL COCULTURE

3-Phenoxybenzoic acid is an intermediate in the degradation of several pyrethroid insecticides in soil. Two pseudomonads were isolated together on vitamin-supplemented nutrient agar from 3-phenoxybenzoate enrichment of an agricultural soil. One isolate, designated 13b, grew on 3-phenoxybenzoate in mineral salts medium producing stoichiometric amounts of phenol. It degraded 3-[phenoxy-14C(U)]phenoxybenzoate to [14C(U)]phenol and did not assimilate any 14C from this molecule. It metabolized [carboxyl-14C]3-phenoxybenzoate but not [14C(U)]phenol. It also produced 4-chlorophenol and p-cresol from 3-(4-chlorophenoxy)benzoate and 3-(4-methylphenoxy)benzoate, respectively. This indicated that isolate 13b transformed the benzoate but not the phenoxy moiety of 3-phenoxybenzoate. The second isolate, designated 13a, did not metabolize 3-phenoxybenzoate but grew on and mineralized phenol. Incubation of 3-phenoxybenzoate with isolates 13a and 13b together resulted in the degradation of both aromatic nuclei.