Stable Carbon Isotope Fractionation During 1,2-Dichloropropane-to-Propene Transformation by an Enrichment Culture Containing Dehalogenimonas Strains and a dcpA Gene

Abstract

A stable enrichment culture derived from Besòs river estuary sediments stoichiometrically dechlorinated 1,2-dichloropropane (1,2-DCP) to propene. Sequential transfers in defined anaerobic medium with the inhibitor bromoethanesulfonate produced a sediment-free culture dechlorinating 1,2-DCP in the absence of methanogenesis. Application of previously published genus-specific primers targeting 16S rRNA gene sequences revealed the presence of a Dehalogenimonas strain, and no amplification was obtained with Dehalococcoides-specific primers. The partial sequence of the 16S rRNA amplicon was 100% identical with Dehalogenimonas alkenigignens strain IP3-3. Also, dcpA, a gene described to encode a corrinoid-containing 1,2-DCP reductive dehalogenase was detected. Resistance of the dehalogenating activity to vancomycin, exclusive conversion of vicinally chlorinated alkanes, and tolerance to short-term oxygen exposure is consistent with the hypothesis that a Dehalogenimonas strain is responsible for 1,2-DCP conversion in the culture. Quantitative PCR showed a positive correlation between the number of Dehalogenimonas 16S rRNA genes copies in the culture and consumption of 1,2-DCP. Compound specific isotope analysis revealed that the Dehalogenimonas-catalyzed carbon isotopic fractionation (εC(bulk)) of the 1,2-DCP-to-propene reaction was -15.0 ± 0.7‰ under both methanogenic and nonmethanogenic conditions. This study demonstrates that carbon isotope fractionation is a valuable approach for monitoring in situ 1,2-DCP reductive dechlorination by Dehalogenimonas strains.

Integrative isotopic and molecular approach for the diagnosis and implementation of an efficient in-situ enhanced biological reductive dechlorination of chlorinated ethenes

“…CEs concentrations were analysed from 500 µL headspace samples by gas chromatography (GC) coupled to a flame ionization detector (FID) as reported by Martín-González et al (2015). VFAs (lactate, pyruvate, acetate, formate) were analysed by high performance liquid chromatography (HPLC) from filtered liquid samples as described elsewhere (Mortan et al, 2017).…”

“…All microcosms were prepared in an anoxic glovebox and incubated in the dark at 25 °C. Microcosms that fully dechlorinated CEs were reamended with TCE and transferred to sterilized anoxic synthetic medium (3-7% v/v) described elsewhere (Martín-González et al, 2015) during the exponential degradation phase of CEs.…”

Use of C–Cl CSIA to elucidate origin and fate of DCM in complex contaminated field sites

“…For all samples, concentrations of target contaminants were quantified by analysing bottles headspace as indicated elsewhere [15]. Lactate and other short fatty-acids were monitored by HPLC [16].…”

Unravelling long-term source removal effects and chlorinated methanes natural attenuation processes by C and Cl stable isotopic patterns at a complex field site

“…For the SO 4 2− isotopic analysis, the dissolved SO 4 2− was precipitated as BaSO 4 according to (Dogramaci et al, 2001 Carbon isotope analyses of CMs (δ 13 C CT , δ 13 C CF and δ 13 C DCM ) were also performed at the CCiT-UB by headspace (HS)-solid phase microextration (HS-SPME) coupled to GC-isotope ratio mass spectrometry (IRMS) Martín-González et al, 2015). Notation is expressed in terms of δ (‰) relative to VPDB (Vienna Pee Dee Belemnite).…”