Microbial dechlorination of 2,3,5,6-tetrachlorobiphenyl under anaerobic conditions in the absence of soil or sediment.
Bacterial enrichment cultures developed with Baltimore Harbor (BH) sediments were found to reductively dechlorinate 2,3,5, 6-tetrachlorobiphenyl (2,3,5,6-CB) when incubated in a minimal estuarine medium containing short-chain fatty acids under anaerobic conditions with and without the addition of sediment. Primary enrichment cultures formed both meta and ortho dechlorination products from 2,3,5,6-CB. The lag time preceding dechlorination decreased from 30 to less than 20 days as the cultures were sequentially transferred into estuarine medium containing dried, sterile BH sediment. In addition, only ortho dechlorination was observed following transfer of the cultures. Sequential transfer into medium without added sediment also resulted in the development of a strict ortho-dechlorinating culture following a lag of more than 100 days. Upon further transfer into the minimal medium without sediment, the lag time decreased to less than 50 days. At this stage all cultures, regardless of the presence of sediment, would produce 2,3,5-CB and 3,5-CB from 2,3,5,6-CB. The strict ortho-dechlorinating activity in the sediment-free cultures has remained stable for more than 1 year through several transfers. These results reveal that the classical microbial enrichment technique using a minimal medium with a single polychlorinated biphenyl (PCB) congener selected for ortho dechlorination of 2,3,5,6-CB. Furthermore, this is the first report of sustained anaerobic PCB dechlorination in the complete absence of soil or sediment.
Department of Microbiology and Immunology, Medical University of South Carolina, Charleston, South Carolina, USA.
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Cutter
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Sowers
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HD
May
D000693:Anaerobiosis; D001419:Bacteria / Q000302:isolation & purification* / Q000378:metabolism*; D015142:Baltimore; D001673:Biodegradation, Environmental; D003470:Culture Media; D019015:Geologic Sediments / Q000382:microbiology*; D011078:Polychlorinated Biphenyls / Q000378:metabolism*; D014871:Water Microbiology
D003470:Culture Media; D011078:Polychlorinated Biphenyls; C078132:2,3,5,6-tetrachlorobiphenyl