%0 Journal Article
%T Spatial Distribution of PCB Dechlorinating Bacteria and Activities in Contaminated Soil
%A Birthe V. Kjellerup
%A Piuly Paul
%A Upal Ghosh
%A Harold D. May
%A Kevin R. Sowers
%J Applied and Environmental Soil Science
%D 2012
%I Hindawi Publishing Corporation
%R 10.1155/2012/584970
%X Soil samples contaminated with Aroclor 1260 were analyzed for microbial PCB dechlorination potential, which is the rate-limiting step for complete PCB degradation. The average chlorines per biphenyl varied throughout the site suggesting that different rates of in situ dechlorination had occurred over time. Analysis of PCB transforming (aerobic and anaerobic) microbial communities and dechlorinating potential revealed spatial heterogeneity of both putative PCB transforming phylotypes and dechlorination activity. Some soil samples inhibited PCB dechlorination in active sediment from Baltimore Harbor indicating that metal or organic cocontaminants might cause the observed heterogeneity of in situ dechlorination. Bioaugmentation of soil samples contaminated with PCBs ranging from 4.6 to 265£¿ppm with a pure culture of the PCB dechlorinating bacterium Dehalobium chlorocoercia DF-1 also yielded heterologous results with significant dechlorination of weathered PCBs observed in one location. The detection of indigenous PCB dehalorespiring activity combined with the detection of putative dechlorinating bacteria and biphenyl dioxygenase genes in the soil aggregates suggests that the potential exists for complete mineralization of PCBs in soils. However, in contrast to sediments, the heterologous distribution of microorganisms, PCBs, and inhibitory cocontaminants is a significant challenge for the development of in situ microbial treatment of PCB impacted soils. 1. Introduction Polychlorinated biphenyls (PCBs) are persistent organic pollutants that are still present in the environment despite a U.S. production ban in 1976 [1]. Prior to this, commercial mixtures of PCBs (trade name Aroclor in the U.S.) were used for a range of industrial applications such as high-voltage transformers, insulating materials, and hydraulic liquids [2, 3]. PCBs are hydrophobic with a high affinity for adsorption to soil particles and for bioaccumulation in lipids causing hepato- and immunotoxicity, carcinogenesis, and affecting endocrine organs and reproduction in humans [4, 5] and animals [6]. Removal of PCBs from impacted sites has, therefore, been a regulatory priority for several decades [7]. Soils contaminated with PCBs can be found worldwide as a result of industrial activity [8]. However, large heterogeneities in contaminant concentration and microbial populations were observed, when the total concentration of PCBs and other contaminants were evaluated on both macro- and microscales [9, 10]. In some cases, the reason for the heterogeneity was caused by the source of contamination
%U http://www.hindawi.com/journals/aess/2012/584970/