QuantArray®-Chlor: Bioremediation Testing for Chlorinated Compounds

Comprehensive Microbial Analysis for Chlorinated Solvent Remediation

QuantArray^®-Chlor analysis quantifies twenty-nine key microorganisms (e.g., Dehalococcoides, Dehalobacter, Dehalogenimonas, etc.) and functional genes (e.g., vinyl chloride reductase, methane monooxygenase, etc.) to assess the potential for reductive dechlorination and aerobic cometabolism of chlorinated solvents as well as competing biological processes.

QuantArray^®-Chlor results simultaneously yet economically illuminate degradation pathways for a broad spectrum of common chlorinated compounds, including chlorinated ethenes, chlorinated ethanes, chlorinated methanes, chlorinated propanes, chlorinated phenols, chlorinated benzenes, and polychlorinated biphenyls (PCBs). When combined with chemical and geochemical groundwater monitoring programs, QuantArray^® provides actionable data that can be used to better understand the subsurface microbial community and increase confidence in site management decisions.

HOW TO USE QUANTARRAY^®-CHLOR:

Along with contaminant concentrations and geochemical parameters, the concentrations of specific microorganisms and functional genes responsible for contaminant biodegradation are a key component of remedy selection and performance monitoring at sites impacted by chlorinated solvents.

Use QuantArray^® to help answer…

• How feasible is MNA? Is enhanced bioremediation needed? Is bioaugmentation needed?
  • What are the concentrations of contaminant degraders under existing conditions?
  • Are degrader concentrations greater in impacted wells than background wells?
  • Based on the MI Database, are concentrations of contaminant degraders low, medium, or high in the plume?

 

• Is enhanced bioremediation effective?
  • Did concentrations of contaminant degraders and functional genes increase in response to treatment?
  • Are additional types of degraders and functional genes now detected that were previously below detection limits?

GENE TARGETS INCLUDED IN A SINGLE QUANTARRAY^®-CHLOR qPCR ANALYSIS

TARGET	CODE	RELEVANCE / DATA INTERPRETATION
Dehalococcoides	DHC	Dehalococcoides (DHC) is the only known bacterial group capable of complete reductive dechlorination of PCE to ethene. Lu et al. have proposed a Dehalococcoides concentration of 1 x 10^4 cells/mL as a screening criterion to identify sites where biological reductive dechlorination is predicted to proceed at “generally useful” rates.
Functional Genes	TCE, BVC, VCR	Three functional genes encoding reductive dehalogenases for TCE, DCE and VC to evaluate the potential for complete reductive dechlorination to ethene.
Dehalobacter	DHBt	Capable of reductive dechlorination of PCE and TCE to cis-DCE but also utilize chlorinated ethanes, common co-contaminants at TCE sites.
Dehalobacter DCM	DCM	Dichloromethane can support growth of a distinct group of Dehalobacter strains via fermentation. The Dehalobacter DCM assays targets the 16S rRNA gene of these strains.
Dehalogenimonas	DHG	Dehalogenimonas spp. are best known for dichloroelimination of chlorinated alkanes. However, the Dehalogenimonas WBC-2 culture and Dehalogenimonas strain GP have been shown to be capable of reductive dechlorination of trans-1,2-dichloroethene and vinyl chloride, respectively.
cerA Reductase	CER	Targets the vinyl chloride reductase gene from Dehalogenimonas strain GP, the only known organism other than Dehalococcoides capable of vinyl chloride reduction.
trans-1,2-DCE Reductase	TDR	Targets the gene for trans-1,2-dichloroethene reductive dehalogenase (TdrA) from Dehalogenimonas sp. WBC-2 involved in the dechlorination of trans-DCE to vinyl chloride.
Desulfitobacterium	DSB	Reductive dechlorination of PCE and TCE to cis-DCE.
Dehalobium chlorocoercia	DECO	Dehalobium chlorocoercia DF-1 has been shown to be capable of reductive dechlorination of HCB, PeCB and 1,2,3,5-TeCB.
Desulfuromonas spp.	DSM	Reductive dechlorination of PCE and TCE to cis-DCE using acetate as an electron donor.
PCE-1 Reductase	PCE-1	Targets the pceA reductase genes for the sequential reductive dechlorination of PCE to cis-DCE by Sulfurospirillum species. In mixed cultures, partial dechlorinators like Sulfurospirillum and Geobacter may be responsible for the majority of reductive dechlorination of PCE to cis-DCE with Dehalococcoides functioning as cis-DCE and vinyl chloride reducing specialists.
PCE-2 Reductase	PCE-2	Targets the pceA reductase genes responsible for the sequential reductive dechlorination of PCE to cis-DCE by Geobacter species.
Chloroform Reductase	CFR	Targets the cfrA gene of Dehalobacter spp. that encodes a reductase enzyme responsible for dechlorination of chloroform and 1,1,1-TCA.
1,1 DCA Reductase	DCA	Targets the 1,1-dichloroethane reductive dehalogenase gene found in some strains of Dehalobacter.
1,2 DCA Reductase	DCAR	Targets the 1,2-dichloroethane reductive dehalogenase gene from members of Desulfitobacterium and Dehalobacter , which dechlorinate 1,2-DCA to ethene.
Soluble Methane Monooxygenase	SMMO	Targets the gene encoding soluble methane monooxygenases which can co-oxidize a broad range of chlorinated compounds including TCE, cis-DCE, and vinyl chloride. Furthermore, soluble methane monooxygenases are generally believed to support greater rates of aerobic cometabolism.
Toluene Dioxygenase	TOD	Toluene dioxygenase has relatively relaxed substrate specificity and mediates the incorporation of both atoms of oxygen into the aromatic ring of benzene and substituted benzenes (toluene and chlorobenzene). Comparison of TOD levels in background and source zone samples from a CB impacted site suggested that CBs promoted growth of TOD containing bacteria
Phenol Hydroxylase	PHE	Phenol hydroxylase catalyzes the continued oxidation and in some cases, the initial oxidation of a variety of monoaromatic compounds. In an independent study, significant increases in numbers of bacteria containing PHE genes corresponded to increases in biodegradation of DCB isomers.
Trichlorobenzene Dioxygenase	TCBO	The TCBO assay targets the genes encoding aromatic dioxygenases responsible for initiating aerobic biodegradation of a number of chlorinated benzenes including chlorobenzene, 1,2-dichlorobenzene, 1,2,4-trichlorobenzene, and 1,2,4,5-tetrachlorobenzene.
Toluene Monooxygenase 2	RDEG	Also targets the ring-hydroxylating toluene monooxygenase genes (toluene-2-monooxygenase). As with RMO, toluene-2-monooxygenases are capable of cometabolism of TCE.
Toluene Monooxygenase	RMO	Targets a group of genes encoding ring-hydroxylating toluene monooxygenase (toluene-3- and toluene-4-monooxygenases) capable of co-oxidation of TCE. In some laboratory studies, TCE or a degradation product has been shown to induce expression of toluene monooxygenases, raising the possibility of TCE cometabolism with alternative (non-aromatic) growth substrates.
Ethene Monooxygenase	ETN	Enumerates functional genes (etnC and etnE) involved in ethene utilization and vinyl chloride (co)metabolism. The ethene monooxygenase (EtnABCD) converts ethene and vinyl chloride to their respective epoxyalkanes, while epoxyalkane:CoM transferase (EtnE) mediates conjugation and breaking of the epoxide.
Dichloromethane Dehalogenase	DCMA	Targets the dcmA gene responsible for aerobic biodegradation of dichloromethane by methylotrophs.
Total Eubacteria	EBAC	Index of total bacterial biomass
Sulfate Reducing Bacteria	APS	Quantification of sulfate reducing bacteria provides an additional line of evidence when evaluating redox conditions and terminal electron accepting processes.
Methanogens	MGN	Methanogens utilize hydrogen and can compete with halorespiring bacteria for available electron donor.