Aerobic biodegradation kinetics and pathway of the novel herbicide ZJ0273 in soils

Degradation of ZJ0273, a recently developed pyrimidynyloxybenzoic-based herbicide, was investigated in five different soils under aerobic conditions. ZJ0273 degradation rate was strongly affected by soil physico-chemical characteristics and the inoculation of ZJ0273-degrading bacteria. Greater organic matter (OM) content, neutral pH and inoculation of ZJ0273-degrading bacteria can increase degradation rate and decrease the half-life value (DT50). At 30 degrees C the biodegradation rate of ZJ0273 reached 4185% in natural (unsterilized) soils. It ranged from 69 to 96% at 90 days after treatment (DAT) in five different types of soils after re-inoculation of Amycolatopsis sp. M3-1 and DT50 decreased by 34 , 81, 16, 20 and 32 days, respectively, in soils S1, S2, S3, S4 and S5. Furthermore, using the six metabolites (M1M6) identified six metabolites (M1M6) by liquid chromatography-mass spectrometry (LC-MS) and their behaviour, a biodegradation pathway of ZJ0273 in soils was proposed. New metabolites, M5 and M6, were found in soils. Biodegradation of ZJ0273 involved continuous biocatalytic reactions, such as de-estering, hydrolysis, acylation, C-N cleavage, de-methyl and ether cleavage reactions. Finally, ZJ0273 was bio-transformed into M4 and M6, which could be degraded and oxidized into CO2 and H2O through the tricarboxylic acid (TCA) cycle.