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  • 1
    Electronic Resource
    Electronic Resource
    Isolation and characterization of Dehalospirillum multivorans gen. nov., sp. nov., a tetrachloroethene-utilizing, strictly anaerobic bacterium (1995)
    Springer
    Archives of microbiology 163 (1995), S. 48-56 
    Details
    ISSN: 1432-072X
    Keywords: Anaerobic dehalogenation ; Reductive dechlorination ; Perchloroethylene ; Tetrachloroethene ; Tetrachloroethene respiration ; cis-1,2-Dichloroethene ; Trichloroethene ; Dehalospirillum multivorans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A strictly anaerobic bacterium dechlorinating tetrachloroethene (perchloroethylene, PCE) via trichloroethene (TCE) to cis-1,2-dichloroethene (DCE) was isolated from activated sludge with pyruvate plus PCE as energy substrates. The organism, called Dehalospirillum multivorans, is a gram-negative spirillum that does not form spores. The G+C content of the DNA was 41.5 mol%. According to 16S rRNA gene sequence analysis, D. multivorans represents a new genus and a new species belonging to the epsilon subdivision of Proteobacteria. Quinones, cytochromes b and c, and corrinoids were extracted from the cells. D. multivorans grew in defined medium with PCE and H2 as sole energy sources and acetate as carbon source; the growth yield under these conditions was 1.4g of cell protein per mol chloride released. Alternatively to PCE, fumarate and nitrate could serve as electron acceptors; sulfate could not replace fumarate, nitrate, or PCE in this respect. In addition to H2, the organism utilized a variety of electron donors for dechlorination (pyruvate, lactate, ethanol, formate, glycerol). Upon growth on pyruvate plus PCE, the main fermentation products formed were acetatc, lactate, DCE, and H2. At optimal pH (7.3–7.6) and temperature (30°C), and in the presence of pyruvate (20mM) and PCE (160μM), a dechlorination rate of about 50 nmol min-1 (mg cell protein)-1 and a doubling time of about 2.5h were obtained with growing cultures. The ability to reduce PCE to DCE appears to be constitutive under the experimental conditions applied since cultures growing in the absence of PCE for several generations immediately started dechlorination when transferred to a medium containing PCE. The organism may be useful for bioremediation of environments polluted with tetrachloroethene.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00262203
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  • 2
    Electronic Resource
    Electronic Resource
    Studies on tetrachloroethene respiration inDehalospirillum multivorans (1996)
    Springer
    Archives of microbiology 166 (1996), S. 379-387 
    Details
    ISSN: 1432-072X
    Keywords: Dehalospirillum multivorans ; Reductive dechlorination ; Tetrachloroethene respiration ; Trichloroethene ; PCE dehalogenase ; Formate dehydrogenase ; Fumarate respiration ; Hydrogenase ; Electron transport chain ; Reversed electron flow ; Ferredoxin ; Menaquinone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Tetrachloroethene (PCE) respiration was studied in the tetrachloroethene-utilizing anaerobe,Dehalospirillum multivorans, with respect to localization of the catabolic enzymes, the electron carriers potentially involved in electron transport, and the response to ionophores and specific inhibitors. Hydrogenase and formate dehydrogenase were recovered in the periplasmic cell fraction and were membrane-associated. Electron-accepting tetrachloroethene dehalogenase was found in the cytoplasmic fraction. In the PCE dehalogenase assay, only artificial electron donors with a standard redox potential of 〈-360 mV were effective electron donors for PCE reduction. Besides these artificial reductants, ferredoxin isolated fromD. multivorans (E′o=-445 mV) could serve as electron donor for PCE reduction. However, the reaction rate with ferredoxin was only 1% of that with methyl viologen, whereas the pyruvate-ferredoxin oxidoreductase exhibited almost the same reaction rates with methyl viologen and ferredoxin as electron acceptors for pyruvate oxidation. Reduced menadione (2-methyl-1,4-naphthoquinone) did not serve as electron donor in the PCE dehalogenase reaction. 2-Heptyl-4-hydroxyquinoline-N-oxide (HOQNO) had no significant effect on PCE dechlorination in cell suspensions and in crude extracts. Whole cells catalyzed the reductive dechlorination of PCE with H2 or formate as electron donors. The dechlorination in cell suspensions rather than in cell extracts was inhibited by the ionophores carbonylcyanide-p-(trifluoromethoxy)-phenylhydrazone (FCCP) and tetrachlorosalicylanilide (TCS), indicating that a membrane potential and/or a pH gradient may be required for the reaction in vivo.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01682983
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  • 3
    Electronic Resource
    Electronic Resource
    Properties of tetrachloroethene and trichloroethene dehalogenase of Dehalospirillum multivorans (1995)
    Springer
    Archives of microbiology 163 (1995), S. 276-281 
    Details
    ISSN: 1432-072X
    Keywords: Tetrachloroethene ; Trichloroethene ; Dichloroethene ; PCE dehalogenase ; TCE dehalogenase ; Corrinoid ; Vitamin B12 ; Dehalospirillum multivorans ; Reductive dechlorination ; Tetrachloroethene respiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Some properties of tetrachloroethene and trichloroethene dehalogenase of the recently isolated, tetrachloroethene-utilizing anaerobe, Dehalospirillum multivorans, were studied with extracts of cells grown on pyruvate plus fumarate. The dehalogenase catalyzed the oxidation of reduced methyl viologen with tetrachloroethene (PCE) or trichloroethene (TCE) as electron acceptor. All other artificial or physiological electron donors tested were ineffective. The PCE and TCE dehalogenase activity was insensitive towards oxygen in crude extracts. When extracts were incubated under anoxic conditions in the presence of titanium citrate as reducing agent, the dehalogenase was rapidly inactivated by propyl iodide (50 μM). Inactivation did not occur in the absence of titanium citrate. The activity of propyl-iodide-treated extracts was restored almost immediately by illumination. The dehalogenase was inhibited by cyanide. The inhibition profile was almost the same under oxic and anoxic conditions independent of the presence or absence of titanium citrate. In addition, N2O, nitrite, and ethylene diamine tetra-acetate (EDTA) were inhibitors of PCE and TCE dehalogenase. Carbon monoxide and azide had no influence on the dehalogenase activity. Trans-1,2-dichloroethene or 1,1-dichloroethene, both of which are isomers of the dechlorination product cis-1,2-dichloroethene, neither inhibited nor inactivated the dehalogenase. PCE and TCE dechlorination appeared to be mediated by the same enzyme since the inhibitors tested had nearly the same effects on the PCE and TCE dehalogenating activity. The data indicated the involvement of a corrinoid and possibly of an additional transition metal in reductive PCE and TCE dechlorination.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00393380
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  • 4
    Electronic Resource
    Electronic Resource
    Isolation and characterization of a methyl chloride utilizing, strictly anaerobic bacterium (1991)
    Springer
    Archives of microbiology 156 (1991), S. 416-421 
    Details
    ISSN: 1432-072X
    Keywords: Methyl chloride utilization ; Homoacetogenic bacteria ; Anaerobic dehalogenation ; Strain MC ; Methylotrophic anaerobes ; Methoxylated aromatic compounds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract From sludge obtained from the sewage digester plant in Stuttgart-Möhringen a strictly anaerobic bacterium was enriched and isolated with methyl chloride as the energy source. The isolate, which was tentatively called strain MC, was nonmotile, gram-positive, and occurred as elongated cocci arranged in chains. Cells of strain MC formed about 3 mol of acetate per 4 mol of CH3Cl consumed, indicating that the organism was a homoacetogenic bacterium fermenting methyl chloride plus CO2 according to: $$\begin{gathered} 4 CH_3 Cl + 2 CO_2 + 2 H_2 O \to 3 CH_3 COO^ - \hfill \\ + 7 H^ + + 4 Cl^ - . \hfill \\ \end{gathered} $$ The organism grew with 2–3% methyl chloride in the gas phase at a doubling time of near 30 h. Dichloromethane was not utilized. The bacterium also grew on carbon monoxide, H2 plus CO2, and methoxylated aromatic compounds. Optimal growth with methyl chloride was observed at 25°C and pH 7.3–7.7. The G+C-content of the DNA was 47.5±1.5%. The methyl chloride conversion appeared to be inducible, since H2 plus CO2-grown cells lacked this ability. From the morphological and physiological characteristics, the isolate could not be affiliated to a known species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00248720
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