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Appl. Environ. Microbiol., 12 1997, 4818-4825, Vol 63, No. 12
Q Wu, DL Bedard and J Wiegel
Reductive dechlorination of the Aroclor 1260 residue in Woods Pond (Lenox,
Mass.) sediment samples was investigated for a year at incubation
temperatures from 4 to 66 degrees C. Sediment slurries were incubated
anaerobically with and without 2,3,4,6-tetrachlorobiphenyl (2346-CB; 350
microM) as a primer for dechlorination of the Aroclor 1260 residue.
Dechlorination of the Aroclor residue occurred only in live samples primed
with 2346-CB and only at 8 to 34 degrees C and 50 to 60 degrees C. The
extent and pattern of polychlorinated biphenyl (PCB) dechlorination were
temperature dependent. At 8 to 34 degrees C, the dechlorination resulted in
28 to 65% decreases of the hexathrough nonachlorobiphenyls and
corresponding increases in the tri- and tetrachlorobiphenyls. At 12 to 30
degrees C, 30 to 40% of the hexa- through nonachlorobiphenyls were
dechlorinated in just 3 months. The optimal temperature for overall
chlorine removal was 20 to 27 degrees C. We observed four different
microbial dechlorination processes with different but partially overlapping
temperature ranges, i.e., Process N (flanked meta dechlorination) at 8 to
30 degrees C, Process P (flanked para dechlorination) at 12 to 34 degrees
C, Process LP (unflanked para dechlorination) at 18 to 30 degrees C, and
Process T (a very restricted meta dechlorination of specific hepta- and
octachlorobiphenyls) at 50 to 60 degrees C. These temperature ranges should
aid in the development of strategies for the enrichment and isolation of
the microorganisms responsible for each dechlorination process. The
incubation temperature determined the relative dominance of the four PCB
dechlorination processes and the extent and products of dechlorination.
Hence, understanding the effects of temperature on PCB dechlorination at
contaminated sites should assist in predicting the environmental fate of
PCBs or planning bioremediation strategies at those sites.
Copyright © 1997, American Society for Microbiology
Temperature determines the pattern of anaerobic microbial dechlorination of Aroclor 1260 primed by 2,3,4,6-tetrachlorobiphenyl in Woods Pond sediment
Department of Microbiology, University of Georgia, Athens 30602, USA.
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