title: Induction of the halobenzoate catabolic pathway and cometabolism of ortho-chlorobenzoates in Pseudomonas aeruginosa 142 grown on glucose-supplemented media.
abstract: The aerobic cometabolism of ortho-substituted chlorobenzoates by Pseudomonas aeruginosa strain 142 growing on glucose-supplemented medium was analyzed. The strain, which can use 2-chlorobenzoate (2-CBA) and 2,4-dichlorobenzoate (2,4-DCBA) as sole carbon and energy sources, showed high rates of 2-CBA metabolism in glucose-fed cells. In contrast, 2,4-DCBA was metabolized only after extended incubation of the full grown culture and depletion of glucose. In addition to the ortho-dehalogenation (ohb142) genes encoding the alpha and beta subunits of the oxygenase component of a 2-halobenzoate dioxygenase, strain 142 harbours a closely related ohbABCDFG gene cluster previously identified in P. aeruginosa JB2 (ohbJB2). The genes for the chlorocatechol ortho-catabolic pathway were identified and sequenced in this strain, showing a near complete identity with the clcABD operon of the pAC27 plasmid. Relative quantification of mRNA by RT-PCR shows a preferential induction of ohb142 by 2-CBA, which is abolished in glucose-grown cultures. The alternate ohbJB2 and clc genes were expressed preferentially in 2,4-DCBA grown cultures. Only ohbJB2 appears to be expressed in the presence of the carbohydrate. Detection of chlorocatechol-1,2-dioxygenase activity in 2,4-DCBA plus glucose grown cultures suggests the presence of an alternate system for the ortho-cleavage of chlorobenzoates. The recruitment of elements from two halobenzoate dioxygenase systems with different induction patterns, together with a chlorocatechol degradative pathway not repressed by carbon catabolite, may allow P. aeruginosa 142 to cometabolize haloaromatics in carbohydrate grown cultures.
authors.affiliation: Departamento de Bioquímica y Biología Molecular IV, Facultad de Veterinaria, Universidad Complutense de Madrid, Spain.
authors.forename: M E
authors.initials: ME
authors.lastname: Corbella
authors.forename: A
authors.initials: A
authors.lastname: Garrido-Pertierra
authors.forename: A
authors.initials: A
authors.lastname: Puyet
mesh_terms: D001673:Biodegradation, Environmental; D050548:Catechol 1,2-Dioxygenase; D002723:Chlorobenzoates / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D003470:Culture Media; D004269:DNA, Bacterial / Q000235:genetics / Q000302:isolation & purification; D049308:Dioxygenases; D005947:Glucose / Q000378:metabolism*; D007527:Isoenzymes / Q000096:biosynthesis; D007700:Kinetics; D010105:Oxygenases / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D011550:Pseudomonas aeruginosa / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D002723:Chlorobenzoates; D003470:Culture Media; D004269:DNA, Bacterial; D007527:Isoenzymes; D010105:Oxygenases; D049308:Dioxygenases; D050548:Catechol 1,2-Dioxygenase; D005947:Glucose