Dual C-Br isotope fractionation indicates distinct reductive dehalogenation mechanisms of 1,2-dibromoethane in dehalococcoides - and dehalogenimonas -containing cultures
Brominated organic compounds such as 1,2-dibromoethane (1,2-DBA) are highly toxic groundwater contaminants. Multi-element compound-specific isotope analysis bears the potential to elucidate the biodegradation pathways of 1,2-DBA in the environment, which is crucial information to assess its fate in...
| Autores: | , , , , , , , , , |
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| Formato: | artículo |
| Fecha de publicación: | 2023 |
| País: | España |
| Recursos: | Universitat Autònoma de Barcelona |
| Repositorio: | Dipòsit Digital de Documents de la UAB |
| Idioma: | inglés |
| OAI Identifier: | oai:ddd.uab.cat:273363 |
| Acesso em linha: | https://ddd.uab.cat/record/273363 https://dx.doi.org/urn:doi:10.1021/acs.est.2c07137 |
| Access Level: | acceso abierto |
| Palavra-chave: | Brominated organic compounds Groundwater contamination Biodegradation Organohalide-respiring bacteria Compound-specific isotope analysis |
| Resumo: | Brominated organic compounds such as 1,2-dibromoethane (1,2-DBA) are highly toxic groundwater contaminants. Multi-element compound-specific isotope analysis bears the potential to elucidate the biodegradation pathways of 1,2-DBA in the environment, which is crucial information to assess its fate in contaminated sites. This study investigates for the first time dual C-Br isotope fractionation during in vivo biodegradation of 1,2-DBA by two anaerobic enrichment cultures containing organohalide-respiring bacteria (i.e., either Dehalococcoides or Dehalogenimonas). Different ε C values (-1.8 ± 0.2 and -19.2 ± 3.5‰, respectively) were obtained, whereas their respective ε Br values were lower and similar to each other (-1.22 ± 0.08 and -1.2 ± 0.5‰), leading to distinctly different trends (Λ = Δδ 13 C/Δδ 81 Br ≈ ε C /ε Br) in a dual C-Br isotope plot (1.4 ± 0.2 and 12 ± 4, respectively). These results suggest the occurrence of different underlying reaction mechanisms during enzymatic 1,2-DBA transformation, that is, concerted dihaloelimination and nucleophilic substitution (S2-reaction). The strongly pathway-dependent Λ values illustrate the potential of this approach to elucidate the reaction mechanism of 1,2-DBA in the field and to select appropriate ε C values for quantification of biodegradation. The results of this study provide valuable information for future biodegradation studies of 1,2-DBA in contaminated sites. New insights into the reaction mechanisms of microbial reductive dehalogenation of brominated ethanes and information relevant to the application of CSIA in field studies. |
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