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
References
[1]
R. D. Kimbrough, “Polychlorinated biphenyls (PCBs) and human health: An update,” Critical Reviews in Toxicology, vol. 25, no. 2, pp. 133–163, 1995.
[2]
A. Fischbein, J. Thornton, M. S. Wolff, J. Bernstein, and I. J. Selifoff, “Dermatological findings in capacitor manufacturing workers exposed to dielectric fluids containing polychlorinated biphenyls (PCBs),” Archives of Environmental Health, vol. 37, pp. 69–74, 1982.
[3]
H. K. Ouw, G. R. Simpson, and D. S. Siyali, “Use and health effects of Aroclor 1242, a polychlorinated biphenyl, in an electrical industry,” Archives of Environmental Health, vol. 31, no. 4, pp. 189–194, 1976.
[4]
S. Safe, K. Connor, K. Ramamoorthy, K. Gaido, and S. Maness, “Human exposure to endocrine-active chemicals: Hazard assessment problems,” Regulatory Toxicology and Pharmacology, vol. 26, pp. 52–58, 1997.
[5]
S. T. Vater, S. F. Velazquez, and V. J. Cogliano, “A case study of cancer data set combinations for PCBs,” Regulatory Toxicology and Pharmacology, vol. 22, no. 1, pp. 2–10, 1995.
[6]
S. De Flora, M. Bagnasco, and P. Zanacchi, “Genotoxic, carcinogenic, and teratogenic hazards in the marine environment, with special reference to the Mediterranean Sea,” Mutation Research, vol. 258, no. 3, pp. 285–320, 1991.
[7]
K. Kannan, H. Nakata, R. Stafford, G. R. Masson, S. Tanabe, and J. P. Giesy, “Bioaccumulation and toxic potential of extremely hydrophobic polychlorinated biphenyl congeners in biota collected at a superfund site contaminated with Aroclor 1268,” Environmental Science and Technology, vol. 32, no. 9, pp. 1214–1221, 1998.
[8]
C. Backe, I. T. Cousins, and P. Larsson, “PCB in soils and estimated soil-air exchange fluxes of selected PCB congeners in the south of Sweden,” Environmental Pollution, vol. 128, no. 1-2, pp. 59–72, 2004.
[9]
J. M. Becker, T. Parkin, C. H. Nakatsu, J. D. Wilbur, and A. Konopka, “Bacterial activity, community structure, and centimeter-scale spatial heterogeneity in contaminated soil,” Microbial Ecology, vol. 51, no. 2, pp. 220–231, 2006.
[10]
W. A. Lead, E. Steinnes, J. R. Bacon, and K. C. Jones, “Polychlorinated biphenyls in UK and Norwegian soils: spatial and temporal trends,” Science of the Total Environment, vol. 193, no. 3, pp. 229–236, 1997.
[11]
W. Wilcke, W. Zech, and J. Kob？a, “PAH-pools in soils along a PAH-deposition gradient,” Environmental Pollution, vol. 92, no. 3, pp. 307–313, 1996.
[12]
H. Lunsdorf, R. W. Erb, W. R. Abraham, and K. N. Timmis, “‘Clay hutches’: a novel interaction between bacteria and clay minerals,” Environmental Microbiology, vol. 2, pp. 161–168, 2000.
[13]
B. Ramakrishnan, T. Lueders, R. Conrad, and M. Friedrich, “Effect of soil aggregate size on methanogenesis and archaeal community structure in anoxic rice field soil,” FEMS Microbiology Ecology, vol. 32, no. 3, pp. 261–270, 2000.
[14]
J. L. M. Rodrigues, C. A. Kachel, M. R. Aiello et al., “Degradation of aroclor 1242 dechlorination products in sediments by Burkholderia xenovorans LB400(ohb) and Rhodococcus sp. strain RHA1(fcb),” Applied and Environmental Microbiology, vol. 72, no. 4, pp. 2476–2482, 2006.
[15]
A. C. Alder, M. M. H？ggblom, S. R. Oppenheimer, and L. Y. Young, “Reductive dechlorination of polychlorinated biphenyls in anaerobic sediments,” Environmental Science and Technology, vol. 27, no. 3, pp. 530–538, 1993.
[16]
P. B. Hatzinger and M. Alexander, “Effect of aging of chemicals in soil on their biodegradability and extractability,” Environmental Science and Technology, vol. 29, no. 2, pp. 537–545, 1995.
[17]
J. A. Field and R. Sierra-Alvarez, “Microbial transformation and degradation of polychlorinated biphenyls,” Environmental Pollution, vol. 155, no. 1, pp. 1–12, 2008.
[18]
D. H. Pieper and M. Seeger, “Bacterial metabolism of polychlorinated biphenyls,” Journal of Molecular Microbiology and Biotechnology, vol. 15, no. 2-3, pp. 121–138, 2008.
[19]
D. E. Fennell, I. Nijenhuis, S. F. Wilson, S. H. Zinder, and M. M. H？ggblom, “Dehalococcoides ethenogenes Strain 195 Reductively Dechlorinates Diverse Chlorinated Aromatic Pollutants,” Environmental Science and Technology, vol. 38, no. 7, pp. 2075–2081, 2004.
[20]
L. Adrian, V. Dudkova, K. Demnerova, and D. L. Bedard, “Dehalococcoides sp. strain CBDB1 extensively dechlorinates the commercial polychlorinated biphenyl mixture aroclor 1260,” Applied and Environmental Microbiology, vol. 75, pp. 4516–4524, 2009.
[21]
L. A. Cutter, J. E. M. Watts, K. R. Sowers, and H. D. May, “Identification of a microorganism that links its growth to the reductive dechlorination of 2,3,5,6-chlorobiphenyl,” Environmental Microbiology, vol. 3, no. 11, pp. 699–709, 2001.
[22]
S. K. Fagervold, H. D. May, and K. R. Sowers, “Microbial reductive dechlorination of Aroclor 1260 in Baltimore Harbor sediment microcosms is catalyzed by three phylotypes within the Phylum chloroflexi,” Applied and Environmental Microbiology, vol. 73, no. 9, pp. 3009–3018, 2007.
[23]
P. S. G. Chain, V. J. Denef, K. T. Konstantinidis et al., “Burkholderia xenovorans LB400 harbors a multi-replicon, 9.73-Mbp genome shaped for versatility,” Proceedings of the National Academy of Sciences of the United States of America, vol. 103, no. 42, pp. 15280–15287, 2006.
[24]
E. Masai, A. Yamada, J. M. Healy et al., “Characterization of biphenyl catabolic genes of gram-positive polychlorinated biphenyl degrader Rhodococcus sp. strain RHA1,” Applied and Environmental Microbiology, vol. 61, no. 6, pp. 2079–2085, 1995.
[25]
K. Furukawa, “Molecular genetics and evolutionary relationship of PCB-degrading bacteria,” Biodegradation, vol. 5, no. 3-4, pp. 289–300, 1994.
[26]
M. J. Hoostal, G. S. Bullerjahn, and R. M. L. McKay, “Molecular assessment of the potential for in situ bioremediation of PCBs from aquatic sediments,” Hydrobiologia, vol. 469, pp. 59–65, 2002.
[27]
R. W. Erb and I. Wagner-Dobler, “Detection of polychlorinated biphenyl degradation genes in polluted sediments by direct DNA extraction and polymerase chain reaction,” Applied and Environmental Microbiology, vol. 59, no. 12, pp. 4065–4073, 1993.
[28]
A. C. Singer, E. S. Gilbert, E. Luepromchai, and D. E. Crowley, “Bioremediation of polychlorinated biphenyl-contaminated soil using carvone and surfactant-grown bacteria,” Applied Microbiology and Biotechnology, vol. 54, no. 6, pp. 838–843, 2000.
[29]
S. Di Toro, G. Zanaroli, and F. Fava, “Intensification of the aerobic bioremediation of an actual site oil historically contaminated by polychlorinated biphenyls (PCBs) through bioaugmentation with a non acclimated, complex source of microorganisms,” Microbial Cell Factories, vol. 5, article no. 11, 2006.
[30]
B. Kuipers, W. R. Cullen, and W. W. Mohn, “Reductive dechlorination of weathered Aroclor 1260 during anaerobic biotreatment of arctic soils,” Canadian Journal of Microbiology, vol. 49, no. 1, pp. 9–14, 2003.
[31]
Q. Wu, K. R. Sowers, and H. D. May, “Establishment of a polychlorinated biphenyl-dechlorinating microbial consortium, specific for doubly flanked chlorines, in a defined, sediment-free medium,” Applied and Environmental Microbiology, vol. 66, no. 1, pp. 49–53, 2000.
[32]
U. Ghosh, A. S. Weber, J. N. Jensen, and J. R. Smith, “Relationship between PCB desorption equilibrium, kinetics, and availability during land biotreatment,” Environmental Science and Technology, vol. 34, no. 12, pp. 2542–2548, 2000.
[33]
B. V. Kjellerup, X. Sun, U. Ghosh, H. D. May, and K. R. Sowers, “Site-specific microbial communities in three PCB-impacted sediments are associated with different in situ dechlorinating activities,” Environmental Microbiology, vol. 10, no. 5, pp. 1296–1309, 2008.
[34]
M. Berkaw, L. Cutter, K. R. Sowers, and H. D. May, “Site-dependent ortho-, meta-, and para-dechlorination of PCBs by anaerobic estuarine and marine sediments enrichments,” Bergen, Norway, 1996.
[35]
T. R. Pulliam Holoman, M. A. Elberson, L. A. Cutter, H. D. May, and K. R. Sowers, “Characterization of a defined 2,3,5,6-tetrachlorobiphenyl- orthodechlorinating microbial community by comparative sequence analysis of genes coding for 16S rRNA,” Applied and Environmental Microbiology, vol. 64, no. 9, pp. 3359–3367, 1998.
[36]
G. Muyzer, E. C. De Waal, and A. G. Uitterlinden, “Profiling of complex microbial populations by denaturing gradient gel electrophoresis analysis of polymerase chain reaction-amplified genes coding for 16S rRNA,” Applied and Environmental Microbiology, vol. 59, no. 3, pp. 695–700, 1993.
[37]
D. J. Lane, B. Pace, G. J. Olsen, D. A. Stahl, M. L. Sogin, and N. R. Pace, “Rapid determination of 16S ribosomal sequences for phylogenetic analysis,” Proceedings of the National Academy of Sciences of the United States of America, vol. 82, no. 20, pp. 6955–6959, 1985.
[38]
R. Seshadri, L. Adrian, D. E. Fouts et al., “Genome sequence of the PCE-dechlorinating bacterium Dehalococcoides ethenogenes,” Science, vol. 307, no. 5706, pp. 105–108, 2005.
[39]
M. Kube, A. Beck, S. H. Zinder, H. Kuhl, R. Reinhardt, and L. Adrian, “Genome sequence of the chlorinated compound-respiring bacterium Dehalococcoides species strain CBDB1,” Nature Biotechnology, vol. 23, no. 10, pp. 1269–1273, 2005.
[40]
O. Faroon, L. Samuel Keith, C. Smith-Simon, and C. De Rosa, Polychlorinated Biphenyls: Human Health Aspects, World Health Organization, Geneva, Switzerland, 2003.
[41]
M. Berkaw, K. R. Sowers, and H. D. May, “Anaerobic ortho dechlorination of polychlorinated biphenyls by estuarine sediments from Baltimore Harbor,” Applied and Environmental Microbiology, vol. 62, no. 7, pp. 2534–2539, 1996.
[42]
Tetra Tech NUS I, 2005 Soil Sampling Summary Report for Site 9 - Stormwater Drainage Ditch, Bioremediation Pilot Study, Naval Support Activity, Pittsburg, Pa, USA, 2005.
[43]
W. Ludwig, O. Strunk, R. Westram et al., “ARB: a software environment for sequence data,” Nucleic Acids Research, vol. 32, no. 4, pp. 1363–1371, 2004.
[44]
D. H. Pieper, “Aerobic degradation of polychlorinated biphenyls,” Applied Microbiology and Biotechnology, vol. 67, no. 2, pp. 170–191, 2005.
[45]
E. R. Master, V. W. M. Lai, B. Kuipers, W. R. Cullen, and W. W. Mohn, “Sequential anaerobic - Aerobic treatment of soil contaminated with weathered aroclor 1260,” Environmental Science and Technology, vol. 36, no. 1, pp. 100–103, 2002.
[46]
L. J. S. Tsuji, B. C. Wainman, I. D. Martin, J. P. Weber, C. Sutherland, and E. Nieboer, “Abandoned Mid-Canada Radar Line sites in the Western James region of Northern Ontario, Canada: a source of organochlorines for First Nations people?” Science of the Total Environment, vol. 370, no. 2-3, pp. 452–466, 2006.
[47]
A. S. Waller, R. Krajmalnik-Brown, F. E. Loffler, and E. A. Edwards, “Multiple reductive-dehalogenase-homologous genes are simultaneously transcribed during dechlorination by dehalococcoides-containing cultures,” Applied and Environmental Microbiology, vol. 71, pp. 8257–8264, 2005.
[48]
D. L. Bedard, J. J. Bailey, B. L. Reiss, and G. Van Slyke Jerzak, “Development and characterization of stable sediment-free anaerobic bacterial enrichment cultures that dechlorinate aroclor 1260,” Applied and Environmental Microbiology, vol. 72, no. 4, pp. 2460–2470, 2006.
[49]
E. R. Hendrickson, J. A. Payne, R. M. Young et al., “Molecular analysis of Dehalococcoides 16S ribosomal DNA from chloroethene-contaminated sites throughout North America and Europe,” Applied and Environmental Microbiology, vol. 68, no. 2, pp. 485–495, 2002.
[50]
S. K. Fagervold, J. E. M. Watts, H. D. May, and K. R. Sowers, “Sequential reductive dechlorination of meta-chlorinated polychlorinated biphenyl congeners in sediment microcosms by two different Chloroflexi phylotypes,” Applied and Environmental Microbiology, vol. 71, no. 12, pp. 8085–8090, 2005.
[51]
B. Nogales, E. R. B. Moore, E. Llobet-Brossa, R. Rossello-Mora, R. Amann, and K. N. Timmis, “Combined use of 16S ribosomal DNA and 16S rRNA to study the bacterial community of polychlorinated biphenyl-polluted soil,” Applied and Environmental Microbiology, vol. 67, no. 4, pp. 1874–1884, 2001.
[52]
B. Nogales, E. R. B. Moore, W. R. Abraham, and K. N. Timmis, “Identification of the metabolically active members of a bacterial community in a polychlorinated biphenyl-polluted moorland soil,” Environmental Microbiology, vol. 1, no. 3, pp. 199–212, 1999.
[53]
Y. C. Cho, O. S. Kwon, R. C. Sokol, C. M. Bethoney, and G. Y. Rhee, “Microbial PCB dechlorination in dredged sediments and the effect of moisture,” Chemosphere, vol. 43, no. 8, pp. 1119–1126, 2001.
[54]
C. Davis, T. Cort, D. Dai, T. H. Illangasekare, and J. Munakata-Marr, “Effects of heterogeneity and experimental scale on the biodegradation of diesel,” Biodegradation, vol. 14, no. 6, pp. 373–384, 2003.
[55]
M. R. Natarajan, H. Wang, R. Hickey, and L. Bhatnagar, “Effect of oxygen and storage conditions on the metabolic activities of polychlorinated biphenyls dechlorinating microbial granules,” Applied Microbiology and Biotechnology, vol. 43, no. 4, pp. 733–738, 1995.
[56]
K. T. Klasson, J. W. Barton, B. S. Evans, and M. E. Reeves, “Reductive microbial dechlorination of indigenous polychlorinated biphenyls in soil using a sediment-free inoculum,” Biotechnology Progress, vol. 12, no. 3, pp. 310–315, 1996.
[57]
R. B. Payne, H. D. May, and K. R. Sowers, “Enhanced reductive dechlorination of polychlorinated biphenyl impacted sediment by bioaugmentation with a dehalorespiring bacterium,” Environmental Science & Technology, vol. 45, pp. 8772–8779, 2011.
[58]
D. A. Abramowicz, M. J. Brennan, H. M. van Dort, and E. L. Gallagher, “Factors influencing the rate of polychlorinated biphenyl dechlorination in Hudson River sediments,” Environmental Science & Technology, vol. 27, pp. 1125–1131, 1993.
