Stable isotope fractionation of gamma-hexachlorocyclohexane (lindane) during reductive dechlorination by two strains of sulfate-reducing bacteria.
Carbon isotope fractionation factors were determined with the dichloro elimination of gamma-hexachlorocyclohexane (gamma-HCH) by the sulfate-reducing bacteria Desulfococcus multivorans DSM 2059 and Desulfovibrio gigas DSM 1382. Both strains are known for cometabolic HCH dechlorination. Degradation experiments with gamma-HCH in concentrations of 22-25 gammaM were carried out using benzoate (for D. multivorans) and lactate (for D. gigas) as electron donors, respectively. Gamma-HCH was dechlorinated by both bacterial strains within four weeks, and the metabolites gamma-3,4,5,6-tetrachlorocyclohexene (gamma-TCCH), chlorobenzene (CB), and benzene were formed. The carbon isotope fractionation of gamma-HCH dechlorination was quantified by the Rayleigh model, using a bulk enrichment factor (epsilon C) of -3.9 +/- 0.6 for D. gigas and -3.4 +/- 0.5 for D. multivorans, which correspond to apparent kinetic isotope effect (AKIEc) values of 1.023 +/- 0.004 or 1.02 +/- 0.003 for stepwise Cl-C bond cleavage. The extent and range of isotope fractionation suggest that gamma-HCH dechlorination can be monitored in anoxic environments by compound-specific isotope analysis (CSIA).
Badea
Silviu-Laurentiu
SL
Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research-UFZ, Permoserstrasse 15, 04318 Leipzig, Germany.
Vogt
Carsten
C
Weber
Stefanie
S
Danet
Andrei-Florin
AF
Richnow
Hans-Hermann
HH
D000693:Anaerobiosis; D001673:Biodegradation, Environmental; D002247:Carbon Isotopes; D005591:Chemical Fractionation; D045286:Desulfovibrio gigas / Q000378:metabolism; D054879:Halogenation; D001556:Hexachlorocyclohexane / Q000737:chemistry* / Q000302:isolation & purification*; D010084:Oxidation-Reduction; D016999:Sulfur-Reducing Bacteria / Q000378:metabolism*
D002247:Carbon Isotopes; D001556:Hexachlorocyclohexane