Abstract:[Background] Quinclorac (QNC) is a highly selective, hormonal, and low-toxic herbicide. It is mainly used to control barnyard grass in rice fields with a long duration. And the growth and development of subsequent crops are easily affected by QNC accumulated in the soil. In addition, the growth and development of animals will be affected by the residual QNC in the environment, as well as the community structure and the abundance of microorganisms also will be affect. [Objective] To isolate and screen a strain of degrading the herbicide QNC from the paddy soil, and determine its degradation-characteristics. [Methods] The strain was identifiedby morphological, physiological and biochemical tests, phospholipid fatty acid (PLFA) microbial identification, 16S rRNA gene sequence. The degradation characteristics of strains with single factor analysis was carried out. [Results] The QNC-degradation strain numbered 15# was screened and identified as Achromobacter sp. The results of the research on the degradation characteristics show that the optimum conditions for strain 15# were 30℃, pH 6.0, initial QNC concentration 100 mg/L, inoculation amount 7%, and added mass fraction 0.1% of yeast extract powder and nitrogen source are peptone. Under the conditions, the degradation rate of QNC could reach 43.0% after cultured 21 d. [Conclusion] A new strain was screened for microbial degradation of QNC and provided a theoretical basis for further research on this strain.
