Microbial reductive dechlorination

Wu Q, DL Bedard, J Wiegel (1997a) Effect of incubation temperature on the route of microbial reductive dechlorination of 2,3,4,6-tetrachlorobiphenyl in polychlorinated biphenyl (PCB)-contaminated and PCB-free freshwater sediments. Appl Environ Microbiol 63 2836-2843. 

Griffin BM, JM Tiedje, FE Loftier (2004) Anaerobic microbial reductive dechlorination of tetrachloroethene to predominantly fra 5-l,2-dichloroethene. Environ Sci Technol 38 4300-4303. 

Bedard DL, JE Quensen III (1995) Microbial reductive dechlorination of polychlorinated biphenyls. In Microbial transformation and Degradation of Toxic Organic Chemicals (Eds LY Yonng, CE Cemiglia), pp. 127-216. Wiley-Liss, New York. 

Tas DO, IN Thomson, FE Loffler, SG Pavlostathis (2006) Kinetics of the microbial reductive dechlorination of pentachloroaniline. Environ Sci Technol 40 4467-4472. 

Lynam, M.M. Kuty, J. Damborsky, J. Koca, and P. Adriaens. 1998. Molecular orbital calculations to describe microbial reductive dechlorination of polychlorinated dioxins. Environ. Toxicol. Chem. 17 988-997. 

Wu et al. (1998) investigated the microbial reductive dechlorination of PCB-1260 in anaerobic slurries of estuarine sediments from Baltimore Harbor, MD. The slurries were amended with 800 ppm PCB-1260 with and without the addition of 2,3,4,5-tetrachlorobiphenyl or 2,3,5,6-tetrachlorobiphenyl and incubated at 30 °C under methanogenic conditions. Without the addition of the tetrachlorobiphenyls, chlorine atoms at the meta and ortho positions on the PCB congeners decreased by 45 and 9%, respectively. When 2,3,4,5-tetrachlorobiphenyl and 2,3,5,6-tetrachlorobiphenyl were added, chlorine atoms at the meta position decreased by 65 and 55% and chlorines at the ortho positions decreased by 18 and 12%, respectively. After 181 d, hexa- and nonachlorobiphenyls decreased by 65, 75, and 88% In PCB-1260 alone, PCB-1260 + 2,3,5,6-tetrachlorobiphenyl, and PCB-1260 + 2,3,4,5-tetrachlorobiphenyl. The investigators concluded that the addition of a single congener stimulated the dechlorination of PCB-1260. 

Pavloststhis, S.G. and Prytula, M.T. Kinetics of the sequential microbial reductive dechlorination of hexachlorobenzene. Environ. Sci TechnoL., 34(18) 4001-4009, 2000. 

Wu, 0., Sowers, K.R., and May, H.D. Microbial reductive dechlorination of Aroclor 1260 in anaerobic slurries of estuarine sediments, Appl Environ. Microbiol, 64 (3) 1052-1058, 1998. 

Following the initial observations and confirmation of microbial reductive dechlorination, a large number of laboratories began to conduct research into this area. Some of this work focused on confirmation and further elucidation of the Hudson River dechlorination (Chen et al., 1988 Rhee et al., 1989, 1993a, b Abramowicz, 1990 Abramowicz et al., 1993). Other work sought evidence for... 

Nies, L. Vogel, T. M. (1991). Identification of the proton source for the microbial reductive dechlorination of 2,3,4,5,6-pentachlorobiphenyl. Applied and Environmental Microbiology, 57, 2771-4. 

Williams, W. A. (1994). Microbial reductive dechlorination of trichlorobiphenyls in anaerobic sediment slurries. Environmental Science Technology, 28, 630-5. 

Yeh, D.H., Pennell, K.D., and Pavlostathis, S.G. (1999). Effect of Tween surfactants on methanogenesis and microbial reductive dechlorination of hexachlorobenzene. Environ. Toxicol. Chem., 18, 1408-1416. 

Bedard D.L., and Quensen, J.F., 111. Microbial reductive dechlorination of polychlorianted biphenyls. In Young, L.Y., and Cemiglia, C.E., editors, Microbial Transformation and Degradation of Toxic Organic Chemicals, John Wiley Sons, Inc., New York, 1995. 

Anaerobic reductive dechlorination of chiral PCBs confirmed that microbial reductive dechlorination in situ was possible in Lake Hartwell [163]. Microcosms with sediments from the same cores [156] spiked with racemic PCB 132 reductively meto-dechlorinated this congener nonenantioselectively to PCB 91, which in mrn was stereoselectively meta-dechlorinated to achiral PCB 51 (Figure4.12). Similarly, PCB 149wasnonstereoselectively /jflra-dechlorinated to PCB 95, in turn enantioselectively meta-dechlorinated to achiral PCB 53 [163]. The enantiomer preferences for PCB 149 dechlorination were consistent between the laboratory microcosms [163] and field observations, suggesting possible similarities in the microbial consortia in both cases. However, PCB 132 was nonracemic in the cores [156], suggesting that either the microbial consortia and/or environmental conditions affecting microbial activity were different between the laboratory and in situ. Much remains unknown about the microbial strains and enzymes involved in PCB anaerobic reductive dechlorination or the factors controlling stereospecificity. 

Figure 4.12 Reductive dechlorination of PCB 132 enantiomers and products in laboratory microcosms of Lake Hartwell sediments over time concentrations (A-C), enantiomer fractions for PCBs 132 (D) and 91 (E). Autoclaved control with racemic PCB 132 added (open circles, crosshatched bars), live treatments with racemic 132 added (filled circles, filled bars). Racemic value of EF —0.5 denoted by dashed line. (Reproduced with permission from Environmental Science and Technology, Changes in Enantiomeric Fractions during Microbial Reductive Dechlorination of PCB 32, PCB 149, and Arocior 1254 In Lake Hartwell Sediment Microcosms, by Usarat Pakdeesusuk, W. jack Jones et al., 37(6), 1100-1107. Copyright (2003) American Chemical Society)...

Bedard, D.L. Quensen J.F. ni. Microbial Reductive Dechlorination of Polychlorinated Biphenyls In Microbial Transformation and Degradation of Toxic Organic Chemicals, L.Y. Young C.E. Cerniglia, editors, Wiley-Liss New York, 1995, p. 127-216. 

Tiedje JM, Quensen IF III, Chee-Sanford J, et al. 1993. Microbial reductive dechlorination of PCBs. Biodegradation 4(4) 231-240. 

Ramsburg, C.A., Abriola, L.M., Pennell, K.D., Loffler, F.E., Gamache, M., Amos, B.K. and Petrovskis, E.A. (2004) Stimulated microbial reductive dechlorination following surfactant treatment at the Bachman road site. Environ. Sci. Technol., 38(22), 5902-5914. 

Booker RS, Pavlostathis SG (2000) Microbial reductive dechlorination of hexachloro-l,3-butadien in a methanogenic enrichment culture, Wat Res 34 (18), 4437-4445. 

Whether these shifts are due to microbial reductive dechlorination which has been observed for toxaphene congeners [51] and for PCBs in sites with relatively high concentrations [52], or is due to shifting SCCP sources is difficult to determine without actual analyses of SCCP enantiomers. If this could be done, it would help to assign sediment half-lives as has been done with PCBs [52], Also, if techniques which detect the tri- and tetrachloro Cjo-Cig alkanes could be employed for analysis of sediment cores, e.g., CACI-MS or MAB-MS, it should be possible to infer the extent of dechlorination (as has been done with toxaphene congeners [51] and for DDT to DDD in sediments [53] since, as noted above, there is evidence from analysis of surface and suspended sediments of greater proportions of CI4 and CI5 homologs than are present in technical products [35],... 

Yeh DH. (2000). Influence of Nonionic Surfactants on the BioavailabiUty and Microbial Reductive Dechlorination of Hexachlorobenzene. PhD Dissertation. Georgia Institute of Technology, Atlanta, GA. 

Figure 19.9. Electrochemically enhanced microbial reductive dechlorination of perchloro-ethene (PCE) and oxidative degradation of vinyl chloride (VC). Stimulated biodegradation is indicated by a chloride increase during electrochemical treatment.

He J, Sung Y, Dollhopf ME, Fathepure BZ, Hedje JM, Loffler EE. (2002). Acetate versus hydrogen as direct electron donor to stimulate the microbial reductive dechlorination process at chloroethene-contaminated sites. Environmental Science Technology 36 3945-3952. 

Another promising approach for the detoxification of PCBs is the finding that anaerobic bacteria dechlorinate PCBs reductively [79, 80]. The authors used anaerobic microorganisms from Hudson River sediment and report that, at PCB concentrations of 700 ppm Aroclor, 63 per cent of the total chlorine was removed in 16 weeks, and the proportion of mono- and dichlorobiphenyls increased from 9 to 88 per cent. Dechlorination occurred primarily from the meta and para positions. These results indicate that reductive dechlorination may be an important environmental fate of PCBs, and suggest that a sequential anaerobic-aerobic biological treatment system for PCBs may be feasible. The proton source for the microbial reductive dechlorination of 2,3,4,5,6-pentachlorobiphenyl has been identified by Nies and Vogel [81]. Tlie authors report that the exact mechanism of the electron transfer for the dechlorination of PCBs is imknown however, they could show that the sotirce of tiie hydrogen atom is the proton from water, and that chloride is released from the PCB. 

Aulenta F et al (2007) Electron transfer from a solid-state electrode assisted by methyl viologen sustains efficient microbial reductive dechlorination of TCE. Environ Sci Technol 41(7) 2554-2559... 

---