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Appl. Environ. Microbiol., Jul 1997, 2836-2843, Vol 63, No. 7
Q Wu, DL Bedard and J Wiegel
We studied the influence of temperature (4 to 66(deg)C) on the microbial
dechlorination of 2,3,4,6-tetrachlorobiphenyl (2,3,4,6-CB) incubated for 1
year in anaerobic sediments from Woods Pond in Lenox, Mass., and Sandy
Creek Nature Center Pond (SCNC) in Athens, Ga. Seven discrete
dechlorination reactions were observed, four of which occurred in both
sediments. These were 2,3,4,6-CB (symbl) 2,4,6-CB, 2,3,4,6-CB (symbl)
2,3,6-CB, 2,4,6-CB (symbl) 2,6-CB, and 2,3,6-CB (symbl) 2,6-CB. Three
additional reactions occurred only in Woods Pond sediment. These were
2,4,6-CB (symbl) 2,4-CB, 2,4-CB (symbl) 2-CB, and 2,4-CB (symbl) 4-CB. The
dechlorination reactions exhibited at least four different temperature
dependencies in SCNC sediment and at least six in Woods Pond sediment. We
attribute the discrete dechlorination reactions to different
polychlorinated biphenyl (PCB)-dechlorinating microorganisms with distinct
specificities. Temperature influenced the timing and the relative
predominance of parallel pathways of dechlorination, i.e., meta versus para
dechlorination of 2,3,4,6-CB and ortho versus para dechlorination of
2,4,6-CB and 2,4-CB. meta dechlorination of 2,3,4,6-CB to 2,4,6-CB
dominated at all tested temperatures except at 18 and 34(deg)C, where para
dechlorination to 2,3,6-CB dominated in some replicates. The dechlorination
of 2,4,6-CB was restricted to (symbl)15 to 30(deg)C in both sediments.
Temperature affected the lag time preceding the dechlorination of 2,4,6-CB
in both sediments and affected the preferred route of its dechlorination in
Woods Pond sediment. para dechlorination dominated at 20(deg)C, and ortho
dechlorination dominated at 15(deg)C, but at 18 and 22 to 30(deg)C the
relative dominance of ortho versus para dechlorination of 2,4,6-CB varied.
These data indicate that field temperatures play a significant role in
controlling the nature and the extent of the PCB dechlorination that occurs
at a given site.
Copyright © 1997, American Society for Microbiology
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
Department of Microbiology and Center for Biological Resource Recovery, University of Georgia, Athens, Georgia 30602, and Environmental Laboratory, GE Corporate Research and Development, Schenectady, New York 12301
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