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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: Key words 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 1.4 g 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 acetate, lactate, DCE, and H2. At optimal pH (7.3–7.6) and temperature (30°C), and in the presence of pyruvate (20 mM) and PCE (160 μM), a dechlorination rate of about 50 nmol min–1 (mg cell protein)–1 and a doubling time of about 2.5 h 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
    Occurrence of corrinoid-containing membrane proteins in anaerobic bacteria (1987)
    Springer
    Archives of microbiology 148 (1987), S. 52-56 
    Details
    ISSN: 1432-072X
    Keywords: Methanogenic bacteria ; Sulfate-reducing bacteria ; Acetogenic bacteria ; Corrinoid ; Methane formation ; Cobalt ; Membrane cobamide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In Methanobacterium thermoautotrophicum a corrinoid-carrying membrane protein complex has been found, to which a tentative role in methane formation has been ascribed. To test this hypothesis representatives from different orders of methanogenic bacteria were examined for membrane-bound cobamides. These species differed in cell carbon precursor, in methane precursor, in occurrence of cytochromes and of the enzyme CO dehydrogenase, and in the systematic position (Methanobacteriales, Methanomicrobiales). All methanogenic bacteria contained cobamides in the membranes in amounts of about 60 nmol/g cell dry weight, in addition to different amounts of cobamides in the soluble cell fraction. The only central metabolic reaction obviously common to all of these methanogens was methyl coenzyme M reduction to CH4. It is concluded that the membrane corrinoid participates in this energy-conserving reaction. Sulfate-reducing and acetogenic bacteria were included in this survey. They contained different amounts of cobamides in the soluble cell fraction but not in the membrane, a possible exception being Acetobacterium woodii.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00429647
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  • 3
    Electronic Resource
    Electronic Resource
    Studies on tetrachloroethene respiration in Dehalospirillum multivorans (1997)
    Springer
    Archives of microbiology 166 (1997), S. 379-387 
    Details
    ISSN: 1432-072X
    Keywords: Key wordsDehalospirillum 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 from D. 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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  • 4
    Electronic Resource
    Electronic Resource
    Isolation of O-demethylase, an ether-cleaving enzyme system of the homoacetogenic strain MC (1997)
    Springer
    Archives of microbiology 168 (1997), S. 136-142 
    Details
    ISSN: 1432-072X
    Keywords: Key words Corrinoid protein ; Ether cleavage ; Hydrogenase ; Methyltransferase ; O-demethylase ; Strain MC ; Tetrahydrofolate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The O-demethylase of the methylotrophic homoacetogenic bacterium strain MC was purified to apparent homogeneity. The enzyme system consisted of four different components that were designated A, B, C, and D according to their elution sequence from the anionic-exchange chromatography column. All four components were essentially required for catalysis of the transfer of the methyl group from phenyl methyl ethers to tetrahydrofolate. According to gel filtration and SDS-PAGE, components A and B were monomers with apparent molecular masses of approximately 26 kDa (subunit 25 kDa) and 36 (subunit 41 kDa), respectively; component C appeared to be a trimeric protein (195 kDa, subunit 67 kDa); and component D was probably a dimer (64 kDa, subunit 30 kDa). Component A contained one corrinoid per monomer. In crude extracts, component D appeared to be the rate-limiting protein for the complete methyl transfer reaction. Additional requirements for the reaction were ATP and low-potential reducing equivalents supplied by either titanium(III) citrate or H2 plus hydrogenase purified from strain MC.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050479
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  • 5
    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: Key words 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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  • 6
    Electronic Resource
    Electronic Resource
    Tetrachloroethene metabolism of Dehalospirillum multivorans (1994)
    Springer
    Archives of microbiology 162 (1994), S. 295-301 
    Details
    ISSN: 1432-072X
    Keywords: Key words     Dehalospirillum multivorans ; Perchloroethylene ; Tetrachloroethene ; Tetrachloroethene dehalogenase ; Trichloroethene ; Dichloroethene ; Reductive dechlorination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract       Dehalospirillum multivorans is a strictly anaerobic bacterium that is able to dechlorinate tetrachloroethene (perchloroethylene; PCE) via trichloroethene (TCE) to cis-1,2-dichloroethene (DCE) as part of its energy metabolism. The present communication describes some features of the dechlorination reaction in growing cultures, cell suspensions, and cell extracts of D. multivorans. Cell suspensi ons catalyzed the reductive dechlorination of PCE with pyruvate as electron donor at specific rates of up to 150 nmol (chloride released) min–1 (mg cell protein)–1 (300 μM PCE initially, pH 7.5, 25° C). The rate of dechlorination depended on the PCE concentration; concentrations higher than 300 μM inhibited dehalogenation. The temperature optimum was between 25 and 30° C; the pH optimum at about 7.5. Dehalogenation was se nsitive to potential alternative electron acceptors such as fumarate or sulfur; nitrate or sulfate had no significant effect on PCE reduction. Propyl iodide (50 μM) almost completely inhibited the dehalogenation of PCE in cell suspensions. Cell extracts mediated the dehalogenation of PCE and of TCE with reduced methyl viologen as the electron donor at specific rates of up to 0.5 μmol (chloride released) min–1 (mgprotein).–1 An abi otic reductive dehalogenation could be excluded since cell extracts heated for 10 min at 95° C were inactive. The PCE dehalogenase was recovered in the soluble cell fraction after ultracentrifugation. The enzyme was not inactivated by oxygen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00301854
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  • 7
    Electronic Resource
    Electronic Resource
    Comparative studies on tetrachloroethene reductive dechlorination mediated by Desulfitobacterium sp. strain PCE-S (1997)
    Springer
    Archives of microbiology 168 (1997), S. 513-519 
    Details
    ISSN: 1432-072X
    Keywords: Key words Corrinoids ; Dehalospirillum multivorans ; Desulfitobacterium ; Tetrachloroethene dehalogenase ; Propyl iodide ; Reductive dechlorination ; Strain PCE-S ; Tetrachloroethene ; Trichloroethene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Tetrachloroethene reductive dechlorination was studied with cell extracts of a newly isolated, tetrachloroethene-utilizing bacterium, Desulfitobacterium sp. strain PCE-S. Tetrachloroethene dehalogenase mediated the reductive dechlorination of tetrachloroethene and trichloroethene to cis-1,2-dichloroethene with artificial electron donors such as methyl viologen. The chlorinated aromatic compounds tested so far were not reduced. A low-potential electron donor (E 0′ 〈 –0.4 V) was required for tetrachloroethene reduction. The enzyme in its reduced state was inactivated by propyl iodide and reactivated by light, indicating the involvement of a corrinoid in reductive tetrachloroethene dechlorination.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050529
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  • 8
    Electronic Resource
    Electronic Resource
    Purification and characterization of the tetrachloroethene reductive dehalogenase of strain PCE-S (1998)
    Springer
    Archives of microbiology 169 (1998), S. 497-502 
    Details
    ISSN: 1432-072X
    Keywords: Key words Corrinoid protein ; Desulfitobacterium ; Iron-sulfur protein ; N-terminal amino acid sequence ; PCE dehalogenase ; Strain PCE-S ; Tetrachloroethene ; reductive dehalogenase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The membrane-associated tetrachloroethene reductive dehalogenase from the tetrachloroethene-reducing anaerobe, strain PCE-S, was purified 165-fold to apparent homogeneity in the presence of the detergent Triton X-100. The purified dehalogenase catalyzed the reductive dechlorination of tetrachloroethene to trichloroethene and of trichloroethene to cis-1,2-dichloroethene with reduced methyl viologen as the electron donor, showing a specific activity of 650 nkat/mg protein. The apparent K m values of the enzyme for tetrachloroethene, trichloroethene, and methyl viologen were 10 μM, 4 μM, and 0.3 mM, respectively. SDS-PAGE revealed a single protein band with an apparent molecular mass of 65 kDa. The apparent molecular mass of the native enzyme was 200 kDa as determined by gel filtration. Tetrachloroethene dehalogenase contained 0.7 ± 0.3 mol corrinoid, 1.0 ± 0.3 mol cobalt, 7.8 ± 0.5 mol iron, and 10.3 ± 2.0 mol acid-labile sulfur per mol subunit. The pH optimum was approximately 7.2, and the temperature optimum was approximately 50 °C. The dehalogenase was oxygen-sensitive with a half-life of approximately 50 min. The N-terminal amino acid sequence of the enzyme was determined, and no significant similarity was found to any part of the amino acid sequence of the tetrachloroethene (PCE) reductive dehalogenase from Dehalospirillum multivorans.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050602
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  • 9
    Electronic Resource
    Electronic Resource
    Isolation and characterization of a carbon monoxide utilizing strain of the acetogen Peptostreptococcus productus (1987)
    Springer
    Archives of microbiology 148 (1987), S. 305-313 
    Details
    ISSN: 1432-072X
    Keywords: Acetogenic bacteria ; Peptostreptococcus productus ; Carbon monoxide utilization ; Cell wall structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract From sludge obtained from the sewage digester plant in Marburg-Cappel a strictly anaerobic bacterium was enriched and isolated with carbon monoxide as the sole energy source. Based on morphological and physiological characteristics the isolate was identified as a strain of Peptostreptococcus productus, which was called strain Marburg. The organism was able to grow on CO (50% at 200 kPa) as the sole energy source at a doubling time of 3 h and converted this substrate to acetate and CO2. The type strain of P. productus was not able to grow at the expense of CO. Electron microscopic investigations of strain Marburg cells revealed a cell wall which was different from that of other Gram-positive prokaryotes. DNA:DNA hybridization studies of the DNA isolated from strain Marburg and the type strain as well as some morphological and physiological properties of both strains confirmed the low degree or relatedness between the two strains.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00456709
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  • 10
    Electronic Resource
    Electronic Resource
    Studies on methyl chloride dehalogenase and O-demethylase in cell extracts of the homoacetogen strain MC based on a newly developed coupled enzyme assay (1996)
    Springer
    Archives of microbiology 165 (1996), S. 18-25 
    Details
    ISSN: 1432-072X
    Keywords: Key words Strain MC ; Methyl chloride ; Methyl ; chloride dehalogenase ; Methoxylated aromatic ; compounds ; O-Demethylase ; Phenylmethyl ethers ; Methyl tetrahydrofolate ; Methylene tetrahydrofolate ; reductase ; Methylene tetrahydrofolate dehydrogenase ; Enzyme activation ; Homoacetogenic bacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An enzyme assay was developed to determine the activities of methyl chloride dehalogenase and O-demethylase of the homoacetogen strain MC. The formation of methyl tetrahydrofolate from tetrahydrofolate and methyl chloride or from tetrahydrofolate and vanillate was coupled to the oxidation of methyl tetrahydrofolate to methylene tetrahydrofolate mediated by methylene tetrahydrofolate reductase purified from Peptostreptococcus productus (strain Marburg) and to the subsequent oxidation of methylene tetrahydrofolate to methenyl tetrahydrofolate catalyzed by methylene tetrahydrofolate dehydrogenase purified from the same organism. To drive the endergonic methyl tetrahydrofolate oxidation with NAD+ as an electron acceptor, the NADH formed in this reaction was reoxidized in the exergonic lactate dehydrogenase reaction. The formation of NADPH and methenyl tetrahydrofolate in the methylene tetrahydrofolate dehydrogenase reaction was followed photometrically at 350 nm; ε350 was about 29.5 mM–1cm–1 (pH 6.5). Using the coupled enzyme assay, the cofactor requirements, the apparent kinetic parameters, the pH and temperature optima of both enzymes, and the effect of inhibitors were determined. The activity of methyl chloride dehalogenase and of O-demethylase was dependent on the presence of ATP; arsenate severely inhibited both enzyme activities in the absence of ATP. The coupled enzyme assay described allows purification and characterization of methyl chloride dehalogenase and O-demethylase and is also appropriate for the enzymatic determination of methyl tetrahydrofolate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050291
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