Cooperative Biodegradation of Procymidone and Its Toxic Metabolite 3,5-Dichloroaniline by a Microbial Consortium

Procymidone is a dicarboximide fungicide; its persistence and the formation of the toxic metabolite 3,5-dichloroaniline (3,5-DCA) pose environmental risks. A microbial strategy was developed to enhance the degradation of procymidone and its intermediates via complementary bacterial metabolism. A procymidone-degrading bacterium, Prescottella equi strain YW-05, was previously isolated from agricultural soil with long-term procymidone application. Strain YW-05 degraded 86% of procymidone (10 mg L−1) within 7 days in mineral medium, exhibiting a half-life of 2.6 days. However, the strain showed a limited ability to degrade the intermediate metabolite 3,5-DCA. Pseudomonas putida strains were screened to degrade dichloroaniline isomers, and Pseudomonas putida KACC 10270T exhibited the highest degradation activity toward 3,5-DCA. Co-inoculation with strain YW-05 and P. putida KACC 10270T enhanced 3,5-DCA degradation, reaching 90.5% removal within 14 days and 92.8% within 28 days. In soil microcosms, co-inoculation accelerated the early removal of 3,5-DCA, with 80.3% removed within 3 days compared with 52.3% in the uninoculated control, and reduced the half-life to 1.4 days. Metabolite analysis using LC-MS/MS revealed 4-chlorocatechol and cis,cis-muconic acid and suggested procymidone degradation proceeded through hydrolytic cleavage, followed by dechlorination and aromatic ring cleavage. These findings highlight the use of complementary microbial consortia as an effective strategy for detoxifying pesticide residues and their toxic intermediates in agricultural soils.