Stable carbon isotope fractionation of chlorinated ethenes by a microbial consortium containing multiple dechlorinating genes

Completely dechlorinating of trichloroethene by a Dehalococcoides mccartyi-containing microbial consortium in the absence of cobalamin

“…8,the -carbon value of TCE in P0 is calculated to be -7.17 ± 0.50‰, the -carbon values of TCE in NC3, NC5B and NC3A likewise are determined to be -7.41 ± 0.63‰, -7.34 ± 0.72‰ and -7.50 ± 0.51‰, respectively. TCE dechlorination by the subcultures with exogenous cobalamin omitting from the culture medium apparently obtained similar -carbon values of TCE with P0, which are all within the extreme boundaries of the 95% CI of the standard condition by this microbial consortium (-7.24 ± 0.59%) (Liu et al, 2018). In consideration of RDases harbouring cobalamin as cofactor within D.mccartyi are directly responsible for TCE reduction, the comparablecarbon values of TCE in P0, NC3, NC5B and NC3A provide de nitive evidence that certain cobalamin biosynthesis organisms within this microbial consortium are crucial to D.mccartyi to resist the starvation of exogenous cobalamin.…”

“…The stable carbon isotope compositions of the TCE were determined using gas chromatography combustion isotope ratio mass spectrometer (GC-C-IRMS; GC, Agilent Technologies, CA, USA; IRMS, Isoprime 100, Elementar, Germany) as described previously (Liu et al, 2018). The 10 mL glass vials were pre-incubated at 60°C in the auto sampler system prior to subsequent isotope analysis, a 60 m DB-624 capillary column with a 0.25 mm internal diameter was applied to chromatographic separation of the headspace samples, and the oven temperature was 45°C for 4 min, then ramped to 80°C within 3.5 min, nally ramped by 15°C/min to 130°C and held for 3 min.…”

“…The 10 mL glass vials were pre-incubated at 60°C in the auto sampler system prior to subsequent isotope analysis, a 60 m DB-624 capillary column with a 0.25 mm internal diameter was applied to chromatographic separation of the headspace samples, and the oven temperature was 45°C for 4 min, then ramped to 80°C within 3.5 min, nally ramped by 15°C/min to 130°C and held for 3 min. The carbon isotope ratios (δ 13 C) as well as the carbon isotopic enrichment factors ( -carbon) of TCE were calculated using the equations available in previous research (Breukelen and Boris, 2007;Coplen, 2011;Liu et al, 2018).…”

“…Meanwhile, partial dechlorination of TCE to less chlorinated intermediates including isomers of dichloroethylenes (DCEs) and vinyl chloride (VC) by organohalide-respiring bacteria is still problematic since their greater threat to environment than TCE generated (Anam et al, 2019;Liu et al, 2018).…”

“…Nowadays, genus of D.mccartyi is a starlit TCE dechlororespirator ever isolated that is specialized in completely metabolizing TCE to non-chlorinated ethene (ETH), and manifold RDases encoded by dechlorinating genes (i.e., tceA, bvcA and vcrA) within these D.mccartyi are directly in charge of the throughout degradation process (Brisson et al, 2012;Liu et al, 2018;Rong et al, 2018).…”