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Appl. Environ. Microbiol., Aug 1995, 2943-2949, Vol 61, No. 8
A Magli, FA Rainey and T Leisinger
A strictly anaerobic two-component culture able to grow exponentially with
a doubling time of 20 h on a medium containing dichloromethane as the
carbon and energy source was characterized. On a medium without sulfate, we
observed (per mol of dichloromethane) a mass balance of 2 mol of chloride,
0.26 mol of acetate, 0.05 mol of formate, and 0.25 mol of carbon in
biomass. One component of the culture, strain DMB, was identified by a 16S
ribosomal DNA analysis as a Desulfovibrio sp. The other component, the
gram-positive organism strain DMC, could not be isolated. It was possible,
however, to associate strain DMC on a medium containing dichloromethane in
a coculture with Acetobacterium woodii or Methanospirillum hungatei.
Coculture of strain DMC with the Archaeon M. hungatei allowed us to
specifically amplify by PCR the 16S rRNA gene of strain DMC. A phylogenetic
analysis of the 16S ribosomal DNA sequence revealed that this organism
groups within the radiation of the Clostridium-Bacillus subphylum and
exhibits the highest levels of sequence similarity (89%) with
Desulfotomaculum orientis and Desulfitobacterium dehalogenans. Since the
novel organism strain DMC was able to grow acetogenically with
dichloromethane when it was associated with one of three metabolically
different partners and since, in contrast to strain DMB, strain DMC
contained carbon monoxide dehydrogenase activity, this bacterium is
responsible for both the dehalogenation of dichloromethane and the
acetogenesis observed in the original two-component culture. The obligatory
dependence of strain DMC on a partner during growth with dichloromethane is
thought to stem from the need for a growth factor produced by the
associated organism.
Copyright © 1995, American Society for Microbiology
Acetogenesis from Dichloromethane by a Two-Component Mixed Culture Comprising a Novel Bacterium
Institute of Microbiology, Swiss Federal Institute of Technology, ETH-Zentrum, CH-8092 Zurich, Switzerland, and Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, D-38124 Braunschweig, Germany
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