Perchlorate binds weakly to soil, is extremely water soluble, and therefore is highly mobile when released into the environment. Fortunately, some bacteria are capable of using perchlorate as a growth supporting electron acceptor producing chloride ion as an end product. Biodegradation of perchlorate is dependent upon three main factors: availability of an electron donor (carbon and energy source), in situ redox conditions/competing electron acceptors, and the presence of organisms capable of perchlorate reduction. A CENSUS® qPCR assay is available to quantify perchlorate reductase genes to evaluate the potential for perchlorate biodegradation during MNA or in response to electron donor addition.
| TARGET | CODE | RELEVANCE / DATA INTERPRETATION |
|---|---|---|
| Perchlorate Reductase | pcrA | Quantifies the gene encoding perchlorate reductase which catalyzes the initial, rate-limiting step in the biodegradation of perchlorate. In some organisms, perchlorate reductase also catalyzes the reduction of chlorate to chlorite. |
| Perchlorate Reductase Sedimenticola spp. | pcrAS | Quantifies the gene encoding perchlorate reductase in Sedimenticola spp. which catalyzes the initial, rate-limiting step in the biodegradation of perchlorate as well as the reduction of chlorate to chlorite. |
| Denitrifying Bacteria | DNF | The DNF assay quantifies the two types of nitrite reductase genes (nirS and nirK, respectively) encoding the second key step in denitrification. While important in any situation where nitrate is serving as the dominant electron acceptor, quantification of denitrifying bacteria can be critical at perchlorate impacted sites. Many, but not all, perchlorate reducing bacteria will utilize nitrate as an electron acceptor potentially limiting perchlorate reduction. |
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