MICROBIAL MONITORING DURING BIOAUGMENTATION WITH DEHALOCOCCOIDES - Bioaugmentation for Groundwater Remediation - page 170

Trichloroethene (TCE)
tceA gene
cis -1,2-Dichloroethene ( cis -1,2-DCE)
tceA gene
Vinyl chloride (VC)
vcrA or bvcA gene
Ethene
Legend
Carbon atom
Chlorine atom
Hydrogen atom
Figure 6.1. Dehalococcoides reductive dechlorinase genes.
6.2 MBTS FOR CHLORINATED ETHENE
BIODEGRADATION
The key microbes with the ability to efficiently dechlorinate chlorinated ethenes, including
dichloroethenes (DCEs) and vinyl chloride (VC), to ethene are Dhc , and a link between Dhc
presence and complete dechlorination to ethene has been established (Ellis et al., 2000 ; He et al.,
2003 ; Hendrickson et al., 2002 ; Lu et al., 2006 ). Bioremediation of contaminated aquifers using
both biostimulation (i.e., electron donor additions) and bioaugmentation with Dhc -containing
consortia or groundwater have been successfully implemented (Lendvay et al., 2003 ; Lookman
et al., 2007 ; Major et al., 2002 ; Ritalahti et al., 2005 ).
Biomarkers have been developed to indicate both Dhc presence and abundance, and
Dhc -specific prognostic and diagnostic tool kits have been designed (Cupples, 2008 ; Holmes
et al., 2006 ;L¨ffler et al., 2000 ; Regeard et al., 2004 ; Ritalahti et al., 2005 , 2006 ). Although the
available tools have been rigorously tested in laboratory settings and are commercially avail-
able, the applications of these tools are still being refined. The correlation between Dhc
biomarker concentrations and evidence of reductive dechlorination in the field has been
explored (Lu et al., 2006 ; Da Silva and Alvarez, 2008 ; Lebr ´ n et al., 2011a ). Studies have
identified a consistent relationship between Dhc cell titers and potential for complete dechlori-
nation to ethene (Lebr ´ n et al., 2011a ).