title: Biodegradation of butachlor by Rhodococcus sp. strain B1 and purification of its hydrolase (ChlH) responsible for N-dealkylation of chloroacetamide herbicides.
abstract: Rhodococcus  sp. strain B1 could degrade 100 mg/L butachlor within 5 days. Butachlor was first hydrolyzed by strain B1 through N-dealkylation, which resulted in the production of butoxymethanol and 2-chloro-N-(2,6-dimethylphenyl)acetamide. Butoxymethanol could be further degraded and utilized as the carbon source for the growth of strain B1, whereas 2-chloro-N-(2,6-dimethylphenyl)acetamide could not be degraded further. The hydrolase designated ChlH, responsible for the N-dealkylation of the side chain of butachlor, was purified 185.1-fold to homogeneity with 16.1% recovery. The optimal pH and temperature of ChlH were observed to be 7.0-7.5 and 30 °C, respectively. This enzyme was also able to catalyze the N-dealkylation of other chloroacetamide herbicides; the catalytic efficiency followed the order alachlor > acetochlor >butachlor > pretilachlor, which indicated that the alkyl chain length influenced the N-dealkylation of the chloroacetamide herbicides. This is the first report on the biodegradation of chloroacetamide herbicides at the enzyme level.
authors.affiliation: College of Life Science, Nanjing Agriculture University, Nanjing, People's Republic of China.
authors.forename: Hong-Ming
authors.initials: HM
authors.lastname: Liu
authors.forename: Li
authors.initials: L
authors.lastname: Cao
authors.forename: Peng
authors.initials: P
authors.lastname: Lu
authors.forename: Haiyan
authors.initials: H
authors.lastname: Ni
authors.forename: Yun-Xiang
authors.initials: YX
authors.lastname: Li
authors.forename: Xin
authors.initials: X
authors.lastname: Yan
authors.forename: Qing
authors.initials: Q
authors.lastname: Hong
authors.forename: Shun-Peng
authors.initials: SP
authors.lastname: Li
mesh_terms: D000081:Acetamides / Q000378:metabolism*; D000083:Acetanilides / Q000378:metabolism*; D000478:Alkylation; D002852:Chromatography, Ion Exchange; D004591:Electrophoresis, Polyacrylamide Gel; D006867:Hydrolases / Q000378:metabolism*; D012240:Rhodococcus / Q000201:enzymology / Q000378:metabolism*; D013379:Substrate Specificity
chemical_list: D000081:Acetamides; D000083:Acetanilides; C078188:2-chloro-N-(ethoxymethyl)-N-(2-methyl-6-(trifluoromethyl)phenyl)acetamide; C054409:butachlor; D006867:Hydrolases