Dechlorinating and Iron Reducing Bacteria Distribution in a TCE-Contaminated Aquifer

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Abstract

Dehalorespiration bioremediation has been considered for chlorinated compound removal from two trichloroethene contaminated groundwater plumes in the OU 5 area of Hill Air Force Base, Utah. The distributions and population densities of the 16S rRNA genes of Bacteria, Dehalococcoides ethenogenes, Desulfuromonas michiganensis, Geobacter spp. and Rhodoferax ferrireducens-like bacteria, as well as the functional genes trichloroethene reductive dehalogenase (tceA) and vinyl chloride reductase (vcrA) were determined in contaminated aquifer material samples. The influence of aquifer physical and chemical properties, including iron availability, on these distributions was evaluated. Twenty aquifer cores were collected. DNA was extracted and analyzed using real-time quantitative polymerase chain reaction (RT-qPCR) to quantify the gene densities. Dehalococcoides population densities were low and unevenly distributed. D. michiganensis was found in 12 cores while Geobacter spp. were found in 8 cores. Rhodoferax ferrireducens-like bacteria were widely distributed. The vcrA gene distribution was relatively uniform and broad but the tceA gene was detectable in only 2 cores. Gene distribution was not related to core clusters derived from physical/chemical characteristics.

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