title: Molecular and carbon isotopic characterization of an anaerobic stable enrichment culture containing Dehalobacterium sp. during dichloromethane fermentation.
abstract: Biodegradation of dichloromethane (DCM) under reducing conditions is of major concern due to its widespread detection in contaminated groundwaters. Here, we report an anaerobic enrichment culture derived from a membrane bioreactor operating in an industrial wastewater treatment plant, capable of fermenting DCM and the brominated analogue dibromomethane (DBM). Comparative analysis of bacterial 16S rDNA-DGGE profiles from fresh liquid medium inoculated with single colonies picked from serial dilution-to-extinction agar vials showed that cultures degrading DCM contained a predominant band belonging to Dehalobacterium, however this band was absent in cultures unable to degrade DCM. Analysis of the microbial composition of the enrichment by bacterial 16S rRNA gene amplicon paired-end sequencing confirmed the presence of Dehalobacterium together with three additional phylotypes belonging to Acetobacterium, Desulfovibrio, and Wolinella, representing all four operational taxonomic units >99.9% of the retrieved sequences. The carbon isotopic fractionation (ε) determined for DCM degradation in this culture was -27±2‰. This value differs from the ε previously reported for the DCM-fermentative bacteria Dehalobacter (-15.5±1.5‰) but they are both significantly different from those reported for facultative methylotrophic organisms (ranging from -45 to -61‰). This significant difference in the ε allows differentiating between hydrolytic transformation of DCM via glutathione-dependent dehalogenases and fermentation pathway.
  The carbon isotopic fractionation of dichloromethane by an enriched Dehalobacterium-containing culture has significant potential to monitor biodegradation of DCM in groundwaters.
authors.affiliation: Departament d'Enginyeria Química, Biològica i Ambiental, Universitat Autònoma de Barcelona (UAB), Carrer de les Sitges s/n, 08193 Bellaterra, Spain.
authors.forename: Alba
authors.initials: A
authors.lastname: Trueba-Santiso
authors.affiliation: Departament de Genètica i Microbiologia, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain.
authors.forename: Eloi
authors.initials: E
authors.lastname: Parladé
authors.affiliation: Grup de Mineralogia Aplicada i Geoquímica de Fluids, Departament de Mineralogia, Petrologia i Geologia Aplicada, Facultat de Ciències de la Terra, Universitat de Barcelona (UB), Martí Franquès s/n, 08028 Barcelona, Spain.
authors.forename: Mònica
authors.initials: M
authors.lastname: Rosell
authors.affiliation: Departament de Genètica i Microbiologia, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain.
authors.forename: Marc
authors.initials: M
authors.lastname: Lliros
authors.affiliation: Departament d'Enginyeria Química, Biològica i Ambiental, Universitat Autònoma de Barcelona (UAB), Carrer de les Sitges s/n, 08193 Bellaterra, Spain.
authors.forename: Siti Hatijah
authors.initials: SH
authors.lastname: Mortan
authors.affiliation: Departament de Genètica i Microbiologia, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain.
authors.forename: Maira
authors.initials: M
authors.lastname: Martínez-Alonso
authors.affiliation: Departament de Genètica i Microbiologia, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain.
authors.forename: Nuria
authors.initials: N
authors.lastname: Gaju
authors.affiliation: Departament d'Enginyeria Química, Biològica i Ambiental, Universitat Autònoma de Barcelona (UAB), Carrer de les Sitges s/n, 08193 Bellaterra, Spain.
authors.forename: Lucía
authors.initials: L
authors.lastname: Martín-González
authors.affiliation: Departament d'Enginyeria Química, Biològica i Ambiental, Universitat Autònoma de Barcelona (UAB), Carrer de les Sitges s/n, 08193 Bellaterra, Spain.
authors.forename: Teresa
authors.initials: T
authors.lastname: Vicent
authors.affiliation: Departament d'Enginyeria Química, Biològica i Ambiental, Universitat Autònoma de Barcelona (UAB), Carrer de les Sitges s/n, 08193 Bellaterra, Spain. Electronic address: ernest.marco@uab.es.
authors.forename: Ernest
authors.initials: E
authors.lastname: Marco-Urrea
mesh_terms: D001673:Biodegradation, Environmental; D002247:Carbon Isotopes / Q000032:analysis*; D005285:Fermentation; D008752:Methylene Chloride / Q000378:metabolism*; D010459:Peptococcaceae / Q000378:metabolism*; D012336:RNA, Ribosomal, 16S; D062065:Wastewater
chemical_list: D002247:Carbon Isotopes; D008752:Methylene Chloride; D012336:RNA, Ribosomal, 16S; D062065:Wastewater
keywords: Biodegradation; Dehalobacter; Dehalobacterium; Dense non-aqueous phase liquid; Isotopic fractionation; Methylene chloride