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Appl. Environ. Microbiol., Nov 1995, 3928-3933, Vol 61, No. 11
X Maymo-Gatell, V Tandoi, JM Gossett and SH Zinder
We have been studying an anaerobic enrichment culture which, by using
methanol as an electron donor, dechlorinates tetrachloroethene (PCE) to
vinyl chloride and ethene. Our previous results indicated that H2 was the
direct electron donor for rductive dechlorination of PCE by the
methanol-PCE culture. Most-probable-number counts performed on this culture
indicated low numbers (< or equal to 10(4)/ml)) of methanogens and PCE
dechlorinators using methanol and high numbers (> or equal to 10(6)/ml))
of sulfidogens, methanol-utilizing acetogens, fermentative heterotrophs,
and PCE dechlorinators using H2. An anaerobic H2-PCE enrichment culture was
derived from a 10(-6) dilution of the methanol- PCE culture. This H2-PCE
culture used PCE at increasing rates over time when transferred to fresh
medium and could be transferred indefinitely with H2 as the electron donor
for the PCE dechlorination, indicating that H2-PCE can serve as an electron
donor-acceptor pair for energy conservation and growth. Sustained PCE
dechlorination by this culture was supported by supplementation with 0.05
mg of vitamin B12 per liter, 25% (vol/vol) anaerobic digestor sludge
supernatant, and 2 mM acetate, which presumably served as a carbon source.
Neither methanol nor acetate could serve as an electron donor for
dechlorination by the H2- PCE culture, and it did not produce CH4 or
acetate from H2-CO2 or methanol, indicating the absence of methanogenic and
acetogenic bacteria. Microscopic observatios of the pruified H2-PCE culture
showed only two major morphotypes: irregular cocci and small rods.
Copyright © 1995, American Society for Microbiology
Characterization of an H2-utilizing enrichment culture that reductively dechlorinates tetrachloroethene to vinyl chloride and ethene in the absence of methanogenesis and acetogenesis
Section of Microbiology, Cornell University, Ithaca, New York 14853- 8101, USA.
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