title: Microbial Toluene Removal in Hypoxic Model Constructed Wetlands Occurs Predominantly via the Ring Monooxygenation Pathway.
abstract: In the present study, microbial toluene degradation in controlled constructed wetland model systems, planted fixed-bed reactors (PFRs), was queried with DNA-based methods in combination with stable isotope fractionation analysis and characterization of toluene-degrading microbial isolates. Two PFR replicates were operated with toluene as the sole external carbon and electron source for 2 years. The bulk redox conditions in these systems were hypoxic to anoxic. The autochthonous bacterial communities, as analyzed by Illumina sequencing of 16S rRNA gene amplicons, were mainly comprised of the families Xanthomonadaceae, Comamonadaceae, and Burkholderiaceae, plus Rhodospirillaceae in one of the PFR replicates. DNA microarray analyses of the catabolic potentials for aromatic compound degradation suggested the presence of the ring monooxygenation pathway in both systems, as well as the anaerobic toluene pathway in the PFR replicate with a high abundance of Rhodospirillaceae. The presence of catabolic genes encoding the ring monooxygenation pathway was verified by quantitative PCR analysis, utilizing the obtained toluene-degrading isolates as references. Stable isotope fractionation analysis showed low-level of carbon fractionation and only minimal hydrogen fractionation in both PFRs, which matches the fractionation signatures of monooxygenation and dioxygenation. In combination with the results of the DNA-based analyses, this suggests that toluene degradation occurs predominantly via ring monooxygenation in the PFRs.
authors.affiliation: Department of Environmental Biotechnology, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany Department of Environmental Microbiology, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany.
authors.forename: P M
authors.initials: PM
authors.lastname: Martínez-Lavanchy
authors.affiliation: Department of Environmental Biotechnology, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany.
authors.forename: Z
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Department of Environmental Biotechnology, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany Department of Proteomics, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany.
authors.forename: V
authors.initials: V
authors.lastname: Lünsmann
authors.affiliation: Department of Environmental Biotechnology, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany.
authors.forename: V
authors.initials: V
authors.lastname: Marin-Cevada
authors.affiliation: Microbial Interactions and Processes Research Group, Helmholtz Centre for Infection Research, Braunschweig, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Vilchez-Vargas
authors.affiliation: Microbial Interactions and Processes Research Group, Helmholtz Centre for Infection Research, Braunschweig, Germany.
authors.forename: D H
authors.initials: DH
authors.lastname: Pieper
authors.affiliation: Department of Environmental Biotechnology, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany.
authors.forename: N
authors.initials: N
authors.lastname: Reiche
authors.affiliation: Department of Environmental Biotechnology, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany.
authors.forename: U
authors.initials: U
authors.lastname: Kappelmeyer
authors.affiliation: Department of Environmental Biotechnology, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany.
authors.forename: V
authors.initials: V
authors.lastname: Imparato
authors.affiliation: RG Microbial Ecology: Metabolism, Genomics, and Evolution/CorpoGen, Bogota, Colombia.
authors.forename: H
authors.initials: H
authors.lastname: Junca
authors.affiliation: Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany.
authors.forename: I
authors.initials: I
authors.lastname: Nijenhuis
authors.affiliation: Department of Environmental Biotechnology, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany.
authors.forename: J A
authors.initials: JA
authors.lastname: Müller
authors.affiliation: Department of Environmental Biotechnology, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany.
authors.forename: P
authors.initials: P
authors.lastname: Kuschk
authors.affiliation: Department of Environmental Biotechnology, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany hermann.heipieper@ufz.de.
authors.forename: H J
authors.initials: HJ
authors.lastname: Heipieper
mesh_terms: D000693:Anaerobiosis; D001419:Bacteria / Q000145:classification / Q000235:genetics; D058448:Biota; D001711:Biotransformation; D002244:Carbon / Q000378:metabolism; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D004783:Environmental Microbiology; D004785:Environmental Pollutants / Q000378:metabolism*; D006859:Hydrogen / Q000378:metabolism; D053858:Metabolic Networks and Pathways; D046228:Microarray Analysis; D006899:Mixed Function Oxygenases / Q000378:metabolism*; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D014050:Toluene / Q000378:metabolism*; D053833:Wetlands
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D004785:Environmental Pollutants; D012336:RNA, Ribosomal, 16S; D014050:Toluene; D002244:Carbon; D006859:Hydrogen; D006899:Mixed Function Oxygenases