Liu Chun-guang;Yang Xin;Lai Yang;Lu Hong-gang;Zeng Wei-min;Geng Gui;Yang Feng-shan

Minist Educ, Engn Res Ctr Agr Microbiol Technol, Harbin 150501, Peoples R China;Heilongjiang Univ, Life Sci Coll, Key Lab Microbiol, Harbin 150080, Peoples R China;Chinese Acad Agr Sci, Sugar Beet Res Inst, Harbin 150080, Peoples R China;Heilongjiang Univ, Crop Res Inst, Harbin 150080, Peoples R China

imazamox;biodegradation;Acinetobacter baumannii;metabolites;herbicide

Herbicidal residues of imazamox are hazardous to some sensitive rotational aftercrops. The aim of the study was to isolate and identify a microbial strain capable of degrading imazamox. The strain 85, capable of efficiently degrading imazamox, was isolated from an imazamox-contaminated soybean field in Heilongjiang Province, China. It was found to degrade 98.61% of 400 mg L-1 imazamox within 48 h by high-performance liquid chromatograph. Through morphological, physiological and biochemical characterization, and the 16S rDNA sequencing, the strain was identified as Acinetobacter baumannii. An optimal degradation condition was obtained and verified: 400 mg L-1 imazamox, 0.1% (volume ratio) initial inoculum, 37 degrees C and pH 7.0. Four main products were captured in the liquid chromatograms and mass spectra, and a pathway for imazamox degradation by IB5 was proposed. This work provides a new suitable candidate for imazamox biodegradation and theoretical evidence for imazamox residue bioremediation. A. baumannii is a common clinical bacteria, but its imazamox-degrading feature has not been reported previously.