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Appl. Environ. Microbiol., Apr 1997, 1225-1229, Vol 63, No. 4
PJM Middeldorp, J De Wolf, AJB Zehnder and G Schraa
A methanogenic microbial consortium capable of reductively dechlorinating
1,2,4-trichlorobenzene (1,2,4-TCB) was enriched from a mixture of polluted
sediments. 1,2,4-TCB was dechlorinated via 1,4-dichlorobenzene (1,4-DCB) to
chlorobenzene (CB). Lactate, which was used as an electron donor during the
enrichment, was converted via propionate and acetate to methane. Glucose,
ethanol, methanol, propionate, acetate, and hydrogen were also suitable
electron donors for dechlorination, whereas formate was not. The addition
of 5% (wt/vol) sterile Rhine River sand was necessary to maintain the
dechlorinating activity of the consortium. The addition of
2-bromoethanesulfonic acid (BrES) inhibited methanogenesis completely but
had no effect on the dechlorination of 1,2,4-TCB. The consortium was also
able to dechlorinate other chlorinated benzenes via various simultaneous
pathways to 1,3,5-TCB, 1,2-DCB, 1,3-DCB, or CB as an end product. The
addition of BrES inhibited several of the simultaneously occurring
dechlorination pathways of 1,2,3,4- and 1,2,3,5-tetrachlorobenzene and of
pentachlorobenzene, which resulted in the formation of CB as the only final
product. Hexachlorobenzene and polychlorinated biphenyls (PCBs) were
dechlorinated after a lag phase of ca. 15 days, showing a dechlorination
pattern that is different from those observed for lower chlorinated
benzenes: only chlorines with two adjacent chlorines were removed. The
results show that the consortium possesses at least three distinct
dechlorination activities toward chlorinated benzenes and PCBs.
Copyright © 1997, American Society for Microbiology
Enrichment and Properties of a 1,2,4-Trichlorobenzene-Dechlorinating Methanogenic Microbial Consortium
Department of Microbiology, Wageningen Agricultural University, NL-6703 CT Wageningen, The Netherlands
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