title: Characterization of the propanil biodegradation pathway in Sphingomonas sp. Y57 and cloning of the propanil hydrolase gene prpH.
abstract: In our previous study, the isoproturon-degrading strain Sphingomonas sp. Y57 was isolated from the wastewater treatment system of an herbicide factory. Interestingly, this strain also showed the ability to degrade propanil (3,4-dichloropropionamilide). The present work reveals that Y57 degrades propanil via the following pathway: propanil was initially hydrolyzed to 3,4-dichloroaniline (3,4-DCA) and then converted to 4,5-dichlorocatechol, which was then subjected to aromatic ring cleavage and further processing. N-acylation and N-deacylation of 3,4-DCA also occurred, and among N-acylation products, 3,4-dichloropropionanilide was found for the first time. The gene encoding the propanil hydrolase responsible for transforming propanil into 3,4-DCA was cloned from Y57 and was designated as prpH. PrpH was expressed in Escherichia coli BL21 and purified using Ni-nitrilotriacetic acid affinity chromatography. PrpH displayed the highest activity against propanil at 40°C and at pH 7.0. The effect of metal ions on the propanil-degrading activity of PrpH was also determined. To our knowledge, this is the first report of a strain that can degrade both propanil and 3,4-DCA and the first identification of a gene encoding a propanil hydrolase in bacteria.
authors.affiliation: Key Lab of Microbiological Engineering of Agricultural Environment, Ministry of Agriculture, College of Life Science, Nanjing Agriculture University, 210095, Nanjing, Jiangsu Province, People's Republic of China.
authors.forename: Ji
authors.initials: J
authors.lastname: Zhang
authors.forename: Ji-Quan
authors.initials: JQ
authors.lastname: Sun
authors.forename: Qiao-Yun
authors.initials: QY
authors.lastname: Yuan
authors.forename: Chao
authors.initials: C
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: D000814:Aniline Compounds / Q000302:isolation & purification; D001673:Biodegradation, Environmental; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics; D005798:Genes, Bacterial; D006867:Hydrolases / Q000235:genetics*; D010957:Plasmids; D011411:Propanil / Q000302:isolation & purification*; D020578:Sphingomonas / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development*; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*
chemical_list: D000814:Aniline Compounds; D014874:Water Pollutants, Chemical; C014464:3,4-dichloroaniline; D011411:Propanil; D006867:Hydrolases