Tracking Genes and Bacteria Responsible for Organohalide Reduction in the Raritan River Basin

News | Raritan River Initiatives | Water Quality

The Raritan River receives wastewater treatment plant (WWTP) effluent, stormwater runoff, combined sewer overflow (CSO), and groundwater infiltration from a variety of sites contaminated with organohalide pollutants. Organohalides are known or suspected carcinogens and some bioaccumulate and enter the food chain, leading to human exposure. In New Jersey, organohalides are present as groundwater and sediment pollutants and drive site remediation needs across the state.  Along the Raritan River there are many organohalide contaminated sites (e.g., American Cyanamid and Kin-Buc Landfill).

Naturally occurring bacteria — the organohalide respiring bacteria (OHRB) — have reductive dehalogenase enzymes (rdhs) that dechlorinate (remove chlorines from the compound) and thus detoxify these compounds. The OHRB are important microbial agents in bioremediation of contaminated sites and in natural attenuation of pollutants.  Donna E. Fennell, Ph.D., Professor and Associate Chair in the Department of Environmental Sciences at the School of Environmental and Biological Sciences in New Brunswick, along with her students, investigated the presence of OHRB and their activity in sediments from the Raritan River and soils from the Rutgers New Brunswick campuses.

Surface sediments were collected via the R/V Rutgers from four river locations. Additionally, dozens of Rutgers University students including freshmen from Professor Fennell’s Byrne Seminar and senior Bioenvironmental Engineers collected soil samples from across the New Brunswick campuses. The Raritan River sediments and Rutgers soil samples were tested to find out if a common organohalide pollutant, trichloroethene (TCE) was dechlorinated by OHRB microbes living in these environments. Students established microcosms—sediment slurries in sealed bottles—to assess the dechlorination of TCE. The river sediment microorganisms dechlorinated TCE, producing less chlorinated end products.  Some Rutgers soils samples also exhibited the same activity.  DNA was extracted from the Raritan River sediments and sequencing indicated the presence of OHRB, including members of the genera Dehalococcoides, Desulfomonile, Dehalobacter, Dehalogenimonas and Dehalobium.

Bacteria that dechlorinate organohalides are present and active in Raritan River sediments and in the soils of Rutgers University.  This project is a novel educational activity for Rutgers students and highlights the importance of specialized microorganisms that degrade toxic pollutants in our local environment. Their ongoing work will further identify the microorganisms and their functional genes in the sediments and soils. Professor Fennell’s students are also mapping this activity to show the distribution of these organisms in our Rutgers environment.

For more information, contact Donna Fennell at  This work was performed with the support of a Rutgers Raritan River Consortium mini-grant.