title: Kinetics of chlorobenzene biodegradation under reduced oxygen levels.
abstract: Focussing on the role of chlorocatechol 1,2-dioxygenase (CC12O), an oxygen-dependent key enzyme in the aerobic catabolism of chlorobenzene (CB), Pseudomonas veronii strain UFZ B549, Acidovorax facilis strain UFZ B530, and a community of indigenous groundwater bacteria were amended with CB degradation under either oxic or hypoxic conditions. All cultures readily degraded CB at high oxygen availability, but had differing abilities to completely degrade CB when exposed to oxygen limitation. For the three cultures very distinct oxygen half-saturation constants (0.3-11.7 muM) for the respective CC12Os were obtained and protein analysis showed that high affinity-type A. facilis and low affinity-type P. veronii express CC12Os, which belong to different structural clusters. From this a functional relation between CC12O type and the ability to cope with efficient ring fission under oxygen limitation is anticipated. Extremely high oxygen affinities for CC12Os support the assumption that truly oxic environments are not an essential requirement to degrade chloro(aromatic) compounds. Tiny quantities of oxygen permanently re-supplied will sufficiently maintain the growth of microaerophilic specialists with the ability to transform chloro(aromatics) via catechol intermediates.
authors.affiliation: Department of Hydrogeology, UFZ, Helmholtz Centre for Environmental Research, Theodor-Lieser-Strasse 4, Halle/Saale, Germany. gerd.balcke@metanomics.de
authors.forename: Gerd Ulrich
authors.initials: GU
authors.lastname: Balcke
authors.forename: Silke
authors.initials: S
authors.lastname: Wegener
authors.forename: Bärbel
authors.initials: B
authors.lastname: Kiesel
authors.forename: Dirk
authors.initials: D
authors.lastname: Benndorf
authors.forename: Michael
authors.initials: M
authors.lastname: Schlömann
authors.forename: Carsten
authors.initials: C
authors.lastname: Vogt
mesh_terms: D000595:Amino Acid Sequence; D001419:Bacteria / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D002722:Chlorobenzenes / Q000378:metabolism*; D002853:Chromatography, Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D007700:Kinetics; D008969:Molecular Sequence Data; D010100:Oxygen / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid
chemical_list: D001426:Bacterial Proteins; D002722:Chlorobenzenes; C031294:chlorobenzene; D010100:Oxygen