title: Degradation of abamectin by newly isolated Stenotrophomonas maltophilia ZJB-14120 and characterization of its abamectin-tolerance mechanism.
abstract: An abamectin (ABM)-degrading bacterium, Stenotrophomonas maltophilia ZJB-14120, was isolated and identified. This strain is capable of degrading 84.82% of ABM at an initial concentration of 200 mg/L over a 48 h incubation period. This strain showed efficient biodegradation ability (7.81 mg/L/h) to ABM and high tolerance (1000 mg/L) to all macrolides tested. In addition to ABM, emamectin, erythromycin and spiramycin can also be degraded by this strain. Modifications involving either reduction of the double bond between C22-C23 or replacement of the C25-group of ABM with a cyclohexyl group can completely inhibit biodegradation of ABM. The ABM-degrading capability of strain ZJB-14120 is likely to be intrinsic to its metabolism and could be inhibited by incubating with erythromycin, azithromycin, spiramycin or rifampicin. A new and successive degradation pathway was proposed based on metabolite analysis. Although there is evidence for metabolite inhibition, this strain has high ABM degradation activity and reusability. Further investigation showed that activated macrolide efflux pump(s) and an undetermined mechanism for regulating the intracellular ABM concentration are responsible for normal uptake of essential metabolites while pumping out excess harmful compounds. Strain ZJB-14120 may provide efficient treatment of water and soil contaminated by toxic levels of abamectin and emamectin.
authors.affiliation: Institute of Bioengineering, Zhejiang University of Technology, No. 18, Chaowang Road, Hangzhou, Zhejiang 310014, PR China; Engineering Research Center of Bioconversion and Biopurification of Ministry of Education, Zhejiang University of Technology, No. 18, Chaowang Road, Hangzhou, Zhejiang 310014, PR China. Electronic address: yuanshan@zjut.edu.cn.
authors.forename: Yuan-Shan
authors.initials: YS
authors.lastname: Wang
authors.affiliation: Institute of Bioengineering, Zhejiang University of Technology, No. 18, Chaowang Road, Hangzhou, Zhejiang 310014, PR China; Engineering Research Center of Bioconversion and Biopurification of Ministry of Education, Zhejiang University of Technology, No. 18, Chaowang Road, Hangzhou, Zhejiang 310014, PR China. Electronic address: zhengxingchang@qq.com.
authors.forename: Xing-Chang
authors.initials: XC
authors.lastname: Zheng
authors.affiliation: Institute of Bioengineering, Zhejiang University of Technology, No. 18, Chaowang Road, Hangzhou, Zhejiang 310014, PR China; Engineering Research Center of Bioconversion and Biopurification of Ministry of Education, Zhejiang University of Technology, No. 18, Chaowang Road, Hangzhou, Zhejiang 310014, PR China. Electronic address: hudei92@sina.com.
authors.forename: Qi-Wei
authors.initials: QW
authors.lastname: Hu
authors.affiliation: Institute of Bioengineering, Zhejiang University of Technology, No. 18, Chaowang Road, Hangzhou, Zhejiang 310014, PR China; Engineering Research Center of Bioconversion and Biopurification of Ministry of Education, Zhejiang University of Technology, No. 18, Chaowang Road, Hangzhou, Zhejiang 310014, PR China. Electronic address: zhengyg@zjut.edu.cn.
authors.forename: Yu-Guo
authors.initials: YG
authors.lastname: Zheng
mesh_terms: D000900:Anti-Bacterial Agents / Q000378:metabolism / Q000494:pharmacology; D001673:Biodegradation, Environmental; D002851:Chromatography, High Pressure Liquid; D004187:Disaccharides / Q000378:metabolism; D007306:Insecticides / Q000378:metabolism* / Q000494:pharmacology; D007559:Ivermectin / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D010802:Phylogeny; D020615:Stenotrophomonas maltophilia / Q000187:drug effects / Q000254:growth & development / Q000302:isolation & purification* / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D004187:Disaccharides; D007306:Insecticides; C048324:abamectin; D007559:Ivermectin; C443359:emamectin
keywords: Bioremediation; Drug efflux pump; Macrolides; Stenotrophomonas maltophilia; Tolerance