title: Microbial degradation of the brominated flame retardant TBNPA by groundwater bacteria: laboratory and field study.
abstract: In the present study, the biodegradation of the brominated flame retardant tribromoneopentylalcohol (TBNPA) by a groundwater enrichment culture was investigated using a dual carbon ((13)C/(12)C)- bromine ((81)Br/(79)Br) stable isotope analysis. An indigenous aerobic bacterial consortium was enriched from the polluted groundwater underlying an industrial site in the northern Negev Desert, Israel, where TBNPA is an abundant pollutant. Aerobic biodegradation was shown to be rapid, with complete debromination within a few days, whereas anaerobic biodegradation was not observed. Biodegradation under aerobic conditions was accompanied by a significant carbon isotope effect with an isotopic enrichment factor of ɛCbulk = -8.8‰ ± 1.5‰, without any detectable bromine isotope fractionation. It was found that molecular oxygen is necessary for biodegradation to occur, suggesting an initial oxidative step. Based on these results, it was proposed that H abstraction from the C-H bond is the first step of TBNPA biodegradation under aerobic conditions, and that the C-H bond cleavage results in the formation of unstable intermediates, which are rapidly debrominated. A preliminary isotopic analysis of TBNPA in the groundwater underlying the industrial area revealed that there are no changes in the carbon and bromine isotope ratio values downstream of the contamination source. Considering that anoxic conditions prevail in the groundwater of the contaminated site, the lack of isotope shifts in TBNPA indicates the lack of TBNPA biodegradation in the groundwater, in accordance with our findings.
authors.affiliation: Department of Environmental Hydrology & Microbiology (EHM), The Zuckerberg Institute for Water Research (ZIWR), The Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Israel. Electronic address: balabannoa@gmail.com.
authors.forename: Noa
authors.initials: N
authors.lastname: Balaban
authors.affiliation: Department of Environmental Hydrology & Microbiology (EHM), The Zuckerberg Institute for Water Research (ZIWR), The Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Israel. Electronic address: anatbern@bgu.ac.il.
authors.forename: Anat
authors.initials: A
authors.lastname: Bernstein
authors.affiliation: Geological Survey of Israel, 30 Malkhei Israel St., Jerusalem 95501, Israel. Electronic address: faina@gsi.gov.il.
authors.forename: Faina
authors.initials: F
authors.lastname: Gelman
authors.affiliation: Department of Environmental Hydrology & Microbiology (EHM), The Zuckerberg Institute for Water Research (ZIWR), The Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Israel. Electronic address: zeevrone@bgu.ac.il.
authors.forename: Zeev
authors.initials: Z
authors.lastname: Ronen
mesh_terms: D001419:Bacteria / Q000378:metabolism*; D001673:Biodegradation, Environmental; D001966:Bromine; D002244:Carbon; D005411:Flame Retardants / Q000378:metabolism*; D060587:Groundwater / Q000382:microbiology*; D054879:Halogenation; D007554:Isotopes; D020005:Propanols / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000378:metabolism*
chemical_list: D005411:Flame Retardants; D007554:Isotopes; D020005:Propanols; D014874:Water Pollutants, Chemical; C545216:tribromoneopentyl alcohol; D002244:Carbon; D001966:Bromine
keywords: Biodegradation; Brominated flame retardants; Bromine isotopes; Carbon isotopes; Compound-specific isotope analysis; Groundwater