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  • Homoacetogenic fermentation  (4)
  • Sulfate-reducing bacterium  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Metabolic pathways and energetics of the acetone-oxidizing, sulfate-reducing bacterium, Desulfobacterium cetonicum (1995)
    Springer
    Archives of microbiology 163 (1995), S. 188-194 
    Details
    ISSN: 1432-072X
    Keywords: Anaerobic degradation ; Acetone ; Carboxylation ; Energetics ; Sulfate-reducing bacterium ; Desulfobacterium cetonicum ; Citric acid cycle ; Glyoxylate cycle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Acetone degradation by cell suspensions of Desulfobacterium cetonicum was CO2-dependent, indicating initiation by a carboxylation reaction. Degradation of butyrate was not CO2-dependent, and acetate accumulated at a ratio of 1 mol acetate per mol butyrate degraded. In cultures grown on acetone, no CoA transfer apparently occurred, and no acetate accumulated in the medium. No CoA-ligase activities were detected in cell-free crude extracts. This suggested that the carboxylation of acetone to acetoacetate, and its activation to acetoacetyl-CoA may occur without the formation of free acetoacetate. Acetoacetyl-CoA was thiolytically cleaved to two acetyl-CoA, which were oxidized to CO2 via the acetyl-CoA/carbon monoxide dehydrogenase pathway. The measured intracellular acyl-CoA ester concentrations allowed the calculation of the free energy changes involved in the conversion of acetone to acetyl-CoA. At in vivo concentrations of reactants and products, the initial steps (carboxylation and activation) must be energy-driven, either by direct coupling to ATP, or coupling to transmembrane gradients. The ΔG′ of acetone conversion to two acetyl-CoA at the expense of the energetic equivalent of one ATP was calculated to lie very close to 0kJ (mol acetone)-1. Assimilatory metabolism was by an incomplete citric acid cycle, lacking an activity oxidatively decarboxylating 2-oxoglutarate. The low specific activities of this cycle suggested its probable function in anabolic metabolism. Succinate and glyoxylate were formed from isocitrate by isocitrate lyase. Glyoxylate thus formed was condensed with acetyl-CoA to form malate, functioning as an anaplerotic sequence. A glyoxylate cycle thus operates in this strictly anaerobic bacterium. Phosphoenolpyruvate (PEP) carboxykinase formed PEP from oxaloacetate. No pyruvate kinase activity was detected. PEP presumably served as a precursor for polyglucose formation and other biosyntheses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00305352
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  • 2
    Electronic Resource
    Electronic Resource
    Fermentative degradation of triethanolamine by a homoacetogenic bacterium (1994)
    Springer
    Archives of microbiology 162 (1994), S. 103-107 
    Details
    ISSN: 1432-072X
    Keywords: Anacrobic degradation ; Triethanolamine ; Homoacetogenic fermentation ; Corrinoids ; Triethanolamine degrading enzyme
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract With triethanolamine as sole source of energy and organic carbon, a strictly anaerobic, gram-positive, rod-shaped bacterium, strain LuTria 3, was isolated from sewage sludge and was assigned to the genus Acetobacterium on the basis of morphological and physiological properties. The G+C content of the DNA was 34.9±1.0 mol %. The new isolate fermented triethanolamine to acetate and ammonia. In cell-free extracts, a triethanolamine-degrading enzyme activity was detected that formed acetaldehyde as reaction product. Triethanolamine cleavage was stimulated 30-fold by added adenosylcobalamin (co-enzyme B12) and inhibited by cyanocobalamin or hydroxocobalamin. Ethanolamine ammonia lyase, acetaldehyde:acceptor oxidoreductase, phosphate acetyltransferase, acetate kinase, and carbon monoxide dehydrogenase were measured in cell-free extracts of this strain. Our results establish that triethanolamine is degraded by a corrinoid-dependent shifting of the terminal hydroxyl group to the subterminal carbon atom, analogous to a diol dehydratase reaction, to form an unstable intermediate that releases acetaldehyde. No anaerobic degradation of triethylamine was observed in similar enrichment assays.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00264381
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  • 3
    Electronic Resource
    Electronic Resource
    Clostridium magnum sp. nov., a non-autotrophic homoacetogenic bacterium (1984)
    Springer
    Archives of microbiology 137 (1984), S. 250-255 
    Details
    ISSN: 1432-072X
    Keywords: Clostridium magnum Species description ; 2,3-Butanediol ; Anaerobic degradation ; Homoacetogenic fermentation ; Syntrophic substrate degradation ; Butanediol formation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A new mesophilic, sporeforming, strictly anaerboic bacterium was isolated form enrichments with 2,3-butanediol as sole substrate and pasteurized freshwater sediment as inoculum. Cells were large, motile rods, and elliptical spores were formed subterminally or centrally. They stained Gram-negative, but no typical outer membrane layer could be observed by electron microscopy of ultrathin sections. 2,3-Butanediol, acetoin, fructose, glucose, sucrose, xylose, malate and citrate served as substrates and were completely converted to acetate with concomitant reduction of carbon dioxide. Growth on glucose (t dmin=1.4 h) was faster than on butanediol (t dmin=3.6 h). No growth occurred on hydrogen/carbon dioxide, on formate or on methanol. The guanine plus cytosine content of the DNA was 29.1%. The new isolate is described as a new species, Clostridium magnum sp. nov.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00414553
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  • 4
    Electronic Resource
    Electronic Resource
    Fermentation of mandelate to benzoate and acetate by a homoacetogenic bacterium (1991)
    Springer
    Archives of microbiology 156 (1991), S. 302-306 
    Details
    ISSN: 1432-072X
    Keywords: Anaerobic degradation ; Mandelate ; Lactate ; Homoacetogenic fermentation ; Mandelate dehydrogenase ; Phenylglyoxylate benzylviologen oxidoreductase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A strictly anaerobic, Gram-positive, rod-shaped bacterium, strain AmMan1, was isolated from freshwater sediment with mandelate (α-hydroxy-phenylacetate) as sole carbon and energy source, and was assigned to the genus Acetobacterium. Only the d-enantiomer of mandelate was degraded, and was fermented to acetate and benzoate. Non-aromatic growth substrates (pyruvate, lactate, malate, glycerol, ethylene glycol, and H2/CO2) were fermented to acetate as sole product. Methoxylated aromatics were demethoxylated to the corresponding phenols. The guanine-plus-cytosine content of the DNA was 36.5±1.5%. Carbon monoxide dehydrogenase, dichlorophenol indophenol-reducing lactate dehydrogenase, NAD-dependent mandelate dehydrogenase, phosphate acetyl transferase, acetate kinase, and pyruvate- or phenylglyoxylate-dependent benzylviologen reductase were measured in mandelate-and/or lactate-grown cells, respectively. A pathway of the homoacetogenic fermentation of mandelate is suggested as another example of incomplete substrate oxidation by homoacetogenic bacteria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00263002
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  • 5
    Electronic Resource
    Electronic Resource
    Metabolic pathways and energetics of the acetone-oxidizing, sulfate-reducing bacterium, Desulfobacterium cetonicum (1995)
    Springer
    Archives of microbiology 163 (1995), S. 188-194 
    Details
    ISSN: 1432-072X
    Keywords: Key words Anaerobic degradation ; Acetone ; Carboxylation ; Energetics ; Sulfate-reducing bacterium ; Desulfobacterium cetonicum ; Citric acid cycle ; Glyoxylate cycle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Acetone degradation by cell suspensions of Desulfobacterium cetonicum was CO2-dependent, indicating initiation by a carboxylation reaction. Degradation of butyrate was not CO2-dependent, and acetate accumulated at a ratio of 1 mol acetate per mol butyrate degraded. In cultures grown on acetone, no CoA transfer apparently occurred, and no acetate accumulated in the medium. No CoA-ligase activities were detected in cell-free crude extracts. This suggested that the carboxylation of acetone to acetoacetate, and its activation to acetoacetyl-CoA may occur without the formation of free acetoacetate. Acetoacetyl-CoA was thiolytically cleaved to two acetyl-CoA, which were oxidized to CO2 via the acetyl-CoA/carbon monoxide dehydrogenase pathway. The measured intracellular acyl-CoA ester concentrations allowed the calculation of the free energy changes involved in the conversion of acetone to acetyl-CoA. At in vivo concentrations of reactants and products, the initial steps (carboxylation and activation) must be energy-driven, either by direct coupling to ATP, or coupling to transmembrane gradients. The ΔG' of acetone conversion to two acetyl-CoA at the expense of the energetic equivalent of one ATP was calculated to lie very close to 0 kJ (mol acetone)–1. Assimilatory metabolism was by an incomplete citric acid cycle, lacking an activity oxidatively decarboxylating 2-oxoglutarate. The low specific activities of this cycle suggested its probable function in anabolic metabolism. Succinate and glyoxylate were formed from isocitrate by isocitrate lyase. Glyoxylate thus formed was condensed with acetyl-CoA to form malate, functioning as an anaplerotic sequence. A glyoxylate cycle thus operates in this strictly anaerobic bacterium. Phosphoenolpyruvate (PEP) carboxykinase formed PEP from oxaloacetate. No pyruvate kinase activity was detected. PEP presumably served as a precursor for polyglucose formation and other biosyntheses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00305352
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  • 6
    Electronic Resource
    Electronic Resource
    Anaerobic degradation of 3-aminobenzoate by a newly isolated sulfate reducer and a methanogenic enrichment culture (1992)
    Springer
    Archives of microbiology 158 (1992), S. 328-334 
    Details
    ISSN: 1432-072X
    Keywords: 3-Aminobenzoate ; Anaerobic degradation ; Sulfate-reducing bacterium ; Methanogenic enrichment culture ; 3-Aminobenzoyl ; CoA synthetase ; 3-Aminobenzoyl-CoA reduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A new rod-shaped, gram-negative, non-sporing sulfate reducer, strain mAB1, was enriched and isolated from marine sediment samples with 3-aminobenzoate as sole electron and carbon source. Strain mAB1 degraded 3-aminobenzoate completely to CO2 and NH3 with stoichiometric reduction of sulfate to sulfide. Cells contained carbon monoxide dehydrogenase, cytochromes, and sulfite reductase P582. Strain mAB1 degraded also benzoate, 4-aminobenzoate, hydroxybenzoates, and some aliphatic compounds. Besides sulfates, also sulfite was reduced with 3-aminobenzoate as electron donor, but not thiosulfate, sulfur, nitrate, or fumarate. The strain grew in sulfide-reduced mineral medium supplemented with 7 vitamins. Strain mAB1 was tentatively affiliated with the genus Desulfobacterium. Experiments with dense cell supsensions showed benzoate accumulation during 3-aminobenzoate degradation under conditions of sulfate limitation or cyanide inhibition. 3-Aminobenzoate was activated to 3-aminobenzoyl-CoA by cell extracts in the presence of ATP, coenzyme A, and Mg2+. Acitivity of 3-aminobenzoyl-CoA synthetase was 16 nmol per min and mg protein, with a KM for 3-aminobenzoate lower than 50 μM. Cell extract of 3-aminobenzoate-grown cells activated also 3-hydroxybenzoate (31.7 nmol per min and mg protein) and benzoate (2.3 nmol per min and mg protein), but not 2-aminobenzoate or 4-aminobenzoate. In the presence of NADH of NADPH, 3-aminobenzoyl-CoA was further metabolized to a not yet identified reduced product. Freshwater enrichments with 3-aminobenzoate in the absence of an extenal electron acceptor led to a stable methanogenic enrichment culture consisting of three types of bacteria. 3-Aminobenzoate was degraded completely to CO2 and stoichiometric amounts of CH4, with intermediary acetate accumulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00245361
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  • 7
    Electronic Resource
    Electronic Resource
    Fermentation of phenoxyethanol to phenol and acetate by a homoacetogenic bacterium (1994)
    Springer
    Archives of microbiology 162 (1994), S. 199-204 
    Details
    ISSN: 1432-072X
    Keywords: Anaerobic degradation ; Phenoxyethanol ; Ether cleavage ; Homoacetogenic fermentation ; Corrinoids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A strictly anaerobic gram-positive, rod-shaped bacterium, strain LuPhet1, was isolated from sewage sludge with phenoxyethanol as sole carbon and energy source, and was assigned to the genus Acetobacterium. The new isolate fermented the alkylaryl ether compound phenoxyethanol stoichiometrically to phenol and acetate, whereas phenoxyacetic acid was not degraded. In cell-free extracts of strain LuPhet1, cleavage of the ether linkage was shown, and acetaldehyde was detected as reaction product. Coenzyme A-dependent acetaldehyde: acceptor oxidoreductase, phosphate acetyltransferase, acetate kinase, and carbon monoxide dehydrogenase were measured in cell-free extracts of this strain. Our results indicate that the ether linkage of phenoxyethanol is cleaved by a shift of the hydroxyl group to the subterminal carbon atom, analogous to a corrinoid-dependent diol dehydratase reaction, to form an unstable hemiacetal that releases phenol and acetaldehyde. Obviously, phenoxyethanol is degraded by the same strategy as in anaerobic degradation of the alkyl ether polyethylene glycol.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00314475
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