Bioremediation and metabolism of clothianidin by mixed bacterial consortia enriched from contaminated soils in Chinese greenhouse

Clothianidin has been widely used for the long-term control of a variety of insect pests. However, extensive use of this pesticide is leading to serious environmental concerns. In this study, the degradation of clothianidin by bacterial consortia SCAH constructed using four potential strains isolated from contaminated soils in vegetable greenhouse was investigated. The strains in the consortia were Ochrobactrum anthropi, Acinetobacter johnsonii, Pseudomonas sp. and Stenotrophomonas maltophilia. In the mineral salt medium, 79.3% of clothianidin (500 mg L-1) was degraded by bacterial consortia SCAH after 15 days. Three metabolites of clothianidin were identified by LC-MS. Results revealed that the consortia SCAH metabolized clothianidin by transformation of the nitroimino moiety to the urea compound and the cleavage of different bonds. The bacterial consortia was applied to bioremediate clothianidin contaminated soil in the presence or absence of additional nutrients. For the treatment with the addition of nutrients, the degradation rate of clothianidin was enhanced in the whole process compared with the treatment without added nutrients, and the clothianidin was almost completely degraded after 45 days. Meanwhile, in the treatment where only consortia SCAH were added, the degradation rate of clothianidin was obviously higher than the natural attenuation (CK) and biostimulation (BS).