Biomedical Engineering Reference
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Figure 7.1. cis-DCE that accumulates from incomplete reductive dechlorination can be completely
mineralized by Polaromonas sp. JS666.
Despite such obstacles, the cometabolic oxidation of cis -DCE has been demonstrated in the
field (Azizian et al., 2005 , 2007 ; Semprini et al., 1990 , 2007 ).
Polaromonas sp. strain JS666 is the first isolate capable of using cis -DCE as its sole carbon
and energy source under aerobic conditions (Coleman et al., 2002a ). It is a promising candidate
for bioaugmentation at cis -DCE-contaminated sites where cis -DCE has migrated downgradient
into an aerobic zone (Figure 7.1 ). Addition of the strain can circumvent the problems associated
with cometabolic oxidation as a bioremediation strategy because it catalyzes rapid degradation
without the addition of a cosubstrate, and the requirements for oxygen are much lower than for
cometabolic transformations. The metabolic capabilities of JS666, development of a molecular
probe for process monitoring, microcosm assessment of site suitability and the preliminary
results of a field-scale study are discussed in this chapter.
7.2 POLAROMONAS SP. STRAIN JS666
Preliminary evidence for the aerobic oxidation of cis -DCE was noted in stream-bed
sediments (Bradley and Chapelle, 1998a , b ), and the microbial mineralization of cis -DCE
was confirmed by the sequential transfer of the sediment from microcosms to defined
medium (Bradley and Chapelle, 2000 ). The organism(s) responsible for cis -DCE transforma-
tion in the sediment were not identified, however, because cis -DCE concentrations were too
low to support significant growth (Bradley and Chapelle, 2000 ). The results provided the first
evidence that cis -DCE could serve as a primary substrate in aerobic metabolism.
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