title: Biotransformation of benzonitrile herbicides via the nitrile hydratase-amidase pathway in rhodococci.
abstract: The aim of this work was to determine the ability of rhodococci to transform 3,5-dichloro-4-hydroxybenzonitrile (chloroxynil), 3,5-dibromo-4-hydroxybenzonitrile (bromoxynil), 3,5-diiodo-4-hydroxybenzonitrile (ioxynil) and 2,6-dichlorobenzonitrile (dichlobenil); to identify the products and determine their acute toxicities. Rhodococcus erythropolis A4 and Rhodococcus rhodochrous PA-34 converted benzonitrile herbicides into amides, but only the former strain was able to hydrolyze 2,6-dichlorobenzamide into 2,6-dichlorobenzoic acid, and produced also more of the carboxylic acids from the other herbicides compared to strain PA-34. Transformation of nitriles into amides decreased acute toxicities for chloroxynil and dichlobenil, but increased them for bromoxynil and ioxynil. The amides inhibited root growth in Lactuca sativa less than the nitriles but more than the acids. The conversion of the nitrile group may be the first step in the mineralization of benzonitrile herbicides but cannot be itself considered to be a detoxification.
authors.affiliation: Institute of Microbiology of the Academy of Sciences of the Czech Republic, Vídeňská 1083, 14220 Prague, Czech Republic.
authors.forename: Alicja B
authors.initials: AB
authors.lastname: Veselá
authors.forename: Helena
authors.initials: H
authors.lastname: Pelantová
authors.forename: Miroslav
authors.initials: M
authors.lastname: Sulc
authors.forename: Martina
authors.initials: M
authors.lastname: Macková
authors.forename: Petra
authors.initials: P
authors.lastname: Lovecká
authors.forename: Markéta
authors.initials: M
authors.lastname: Thimová
authors.forename: Fabrizia
authors.initials: F
authors.lastname: Pasquarelli
authors.forename: Martina
authors.initials: M
authors.lastname: Pičmanová
authors.forename: Miroslav
authors.initials: M
authors.lastname: Pátek
authors.forename: Tek Chand
authors.initials: TC
authors.lastname: Bhalla
authors.forename: Ludmila
authors.initials: L
authors.lastname: Martínková
mesh_terms: D000577:Amides / Q000378:metabolism / Q000633:toxicity; D000581:Amidohydrolases / Q000378:metabolism*; D001549:Benzamides / Q000378:metabolism; D001711:Biotransformation; D006540:Herbicides / Q000737:chemistry / Q000378:metabolism*; D006836:Hydro-Lyases / Q000378:metabolism*; D006868:Hydrolysis; D007462:Iodobenzenes / Q000378:metabolism; D018545:Lactuca / Q000187:drug effects / Q000254:growth & development; D009570:Nitriles / Q000737:chemistry / Q000378:metabolism* / Q000633:toxicity; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D012240:Rhodococcus / Q000378:metabolism*
chemical_list: D000577:Amides; D001549:Benzamides; D006540:Herbicides; D007462:Iodobenzenes; D009570:Nitriles; C008161:ioxynil; C014356:benzonitrile; C057454:2,6-dichlorobenzamide; D000581:Amidohydrolases; C019665:amidase; D006836:Hydro-Lyases; C048831:nitrile hydratase; C584256:chloroxynil; C006826:bromoxynil; C055869:dichlobanil