title: Geochemical Parameters and Reductive Dechlorination Determine Aerobic Cometabolic vs Aerobic Metabolic Vinyl Chloride Biodegradation at Oxic/Anoxic Interface of Hyporheic Zones.
abstract: Hyporheic zones mediate vinyl chloride (VC) biodegradation in groundwater discharging into surface waters. At the oxic/anoxic interface (OAI) of hyporheic zones subjected to redox oscillations, VC is degraded via coexisting aerobic ethenotrophic and anaerobic reductive dechlorination pathways. However, the identity of aerobic VC degradation pathways (cometabolic vs metabolic) and their interactions with reductive dechlorination in relation to riverbed sediment geochemistry remain ill-defined. We addressed this using microcosms containing OAI sediments incubated under fluctuating oxic/anoxic atmosphere. Under oxic atmosphere, aerobic metabolic VC oxidation was absent in sediments with high total organic carbon (TOC) and VC was reductively dechlorinated to ethene. Ethene was oxidized by ethenotrophs that can degrade VC cometabolically. Contrastingly, VC was metabolically oxidized by ethenotrophs in low-TOC sediments with low reductive dechlorination potential. Accordingly, enrichment and isolation of metabolic VC-oxidizing ethenotrophs was successful only from the low-TOC sediment. Sequence analysis of etnE genes from the microcosms as well phylogenetic typing of the isolates showed that ethenotrophs in the sediments were facultative anaerobic Proteobacteria capable of coping with OAI-associated redox fluctuations. Our results suggest that local sediment heterogeneity supports/selects divergent VC degradation processes at the OAI and that high reductive dechlorination potential suppresses development of aerobic metabolic VC oxidation potential.
authors.affiliation: Laboratory of Microbiology, Wageningen University & Research , Stippeneng 4, 6708 WE Wageningen, The Netherlands.|Flemish Institute for Technological Research (VITO), Separation and Conversion Technology, Boeretang 200, 2400 Mol, Belgium.|KU Leuven , Division of Soil and Water Management, Kasteelpark Arenberg 20, B-3001 Heverlee, Belgium.
authors.forename: Siavash
authors.identifier: 0000-0002-2793-2321
authors.initials: S
authors.lastname: Atashgahi
authors.affiliation: Laboratory of Microbiology, Wageningen University & Research , Stippeneng 4, 6708 WE Wageningen, The Netherlands.
authors.forename: Yue
authors.initials: Y
authors.lastname: Lu
authors.affiliation: Laboratory of Microbiology, Wageningen University & Research , Stippeneng 4, 6708 WE Wageningen, The Netherlands.
authors.forename: Javier
authors.initials: J
authors.lastname: Ramiro-Garcia
authors.affiliation: Laboratory of Microbiology, Wageningen University & Research , Stippeneng 4, 6708 WE Wageningen, The Netherlands.
authors.forename: Peng
authors.initials: P
authors.lastname: Peng
authors.affiliation: Laboratory of Microbiology, Wageningen University & Research , Stippeneng 4, 6708 WE Wageningen, The Netherlands.
authors.forename: Farai
authors.initials: F
authors.lastname: Maphosa
authors.affiliation: Laboratory of Microbiology, Wageningen University & Research , Stippeneng 4, 6708 WE Wageningen, The Netherlands.
authors.forename: Detmer
authors.initials: D
authors.lastname: Sipkema
authors.affiliation: Flemish Institute for Technological Research (VITO), Separation and Conversion Technology, Boeretang 200, 2400 Mol, Belgium.
authors.forename: Winnie
authors.initials: W
authors.lastname: Dejonghe
authors.affiliation: Laboratory of Microbiology, Wageningen University & Research , Stippeneng 4, 6708 WE Wageningen, The Netherlands.
authors.forename: Hauke
authors.initials: H
authors.lastname: Smidt
authors.affiliation: KU Leuven , Division of Soil and Water Management, Kasteelpark Arenberg 20, B-3001 Heverlee, Belgium.
authors.forename: Dirk
authors.initials: D
authors.lastname: Springael
mesh_terms: D001673:Biodegradation, Environmental; D060587:Groundwater / Q000382:microbiology; D010084:Oxidation-Reduction; D010802:Phylogeny; D014752:Vinyl Chloride / Q000378:metabolism*
chemical_list: D014752:Vinyl Chloride