Publication Detail

Community Composition and Abundance of Bacteria Inside a Permeable Reactive NITREX™ Barrier

Kenley Hiller, Collin Knauss, Sarah Feinman, Jennifer L. Bowen
1 pp.
MITSG 13-28
$5.50 DOM / $7.50 INT

Eutrophication is a growing problem in coastal systems. Increased nitrate flowing into estuaries causes phytoplankton and macroalgal blooms, which lead to hypoxia and losses in diversity. Scientists at the Marine Biological Laboratory in Woods Hole, MA therefore installed a prototype permeable reactive barrier (PRB) to test its efficacy at removing this excess nitrate from groundwater. The barrier consists of woodchips that, by providing a source of organic matter, support a large community of denitrifying bacteria. We hypothesize that the barrier will facilitate removal of nitrate, that there will be more denitrifiers in the barrier than upgradient or adjacent to it, and that the community structure of the denitrifiers will be different relative to a control site with no barrier. Previously collected geochemical data indicate that the barrier’s bacteria remove much of the nitrate in groundwater. However, no molecular work has been done to analyze the denitrifying bacteria themselves. To elucidate the different nitrate-reduction pathways occurring in the barrier, we examined the community structure and abundance of the nirS gene. This encodes a nitrite reductase enzyme that facilitates a key step in denitrificaction. Data thus far indicate that the copy number of nirS gene is higher within the barrier than outside it, indicating that more denitrifying bacteria are present within the barrier relative to a control site. Mitigation strategies such as the PRB, which enhance the community of denitrifying bacteria, offer one way to combat eutrophication.

type: General reports, fact sheets, posters

Parent Project

Project No.: 2012-R/RC-129
Title: Microbial community composition of permeable reactive barriers: who is really doing the work?