title: Biodegradation of chloroacetamide herbicides by Paracoccus sp. FLY-8 in vitro.
abstract: A butachlor-degrading strain, designated FLY-8, was isolated from rice field soil and was identified as Paracoccus sp. Strain FLY-8 could degrade and utilize six chloroacetamide herbicides as carbon sources for growth, and the degradation rates followed the order alachlor > acetochlor > propisochlor > butachlor > pretilachlor > metolachlor. The influence of molecular structure of the chloroacetamide herbicides on the microbial degradation rate was first analyzed; the results indicated that the substitutions of alkoxymethyl side chain with alkoxyethyl side chain greatly reduced the degradation efficiencies; the length of amide nitrogen's alkoxymethyl significantly affected the biodegradability of these herbicides: the longer the alkyl was, the slower the degradation efficiencies occurred. The phenyl alkyl substituents have no obvious influence on the degradation efficiency. The pathway of butachlor complete mineralization was elucidated on the basis of the results of metabolite identification and enzyme assays. Butachlor was degraded to alachlor by partial C-dealkylation and then converted to 2-chloro-N-(2,6-dimethylphenyl)acetamide by N-dealkylation, which subsequently transformed to 2,6-diethylaniline, which was further degraded via the metabolites aniline and catechol, and catechol was oxidized through an ortho-cleavage pathway. This study highlights an important potential use of strain FLY-8 for the in situ bioremediation of chloroacetamide herbicides and their metabolite-contaminated environment.
authors.affiliation: Key Laboratory of Microbiological Engineering of Agricultural Environment, Ministry of Agriculture, Life Sciences College of Nanjing Agricultural University, Nanjing, Jiangsu, People's Republic of China.
authors.forename: Jun
authors.initials: J
authors.lastname: Zhang
authors.forename: Jin-Wei
authors.initials: JW
authors.lastname: Zheng
authors.forename: Bin
authors.initials: B
authors.lastname: Liang
authors.forename: Cheng-Hong
authors.initials: CH
authors.lastname: Wang
authors.forename: Shu
authors.initials: S
authors.lastname: Cai
authors.forename: Ying-Ying
authors.initials: YY
authors.lastname: Ni
authors.forename: Jian
authors.initials: J
authors.lastname: He
authors.forename: Shun-Peng
authors.initials: SP
authors.lastname: Li
mesh_terms: D000081:Acetamides / Q000737:chemistry / Q000378:metabolism*; D001673:Biodegradation, Environmental; D006540:Herbicides / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D010230:Paracoccus / Q000145:classification / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D010802:Phylogeny; D012988:Soil Microbiology
chemical_list: D000081:Acetamides; D006540:Herbicides; C013874:chloroacetamide