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  • Butyrate fermentation  (3)
  • Sulfate-reducing bacterium  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 163 (1995), S. 188-194 
    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.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 154 (1990), S. 342-348 
    ISSN: 1432-072X
    Keywords: Clostridium homopropionicum sp. nov. ; Clostridium propionicum ; α-Dehydration ; γ-Dehydration ; Butyrate fermentation ; Propionate fermentation ; Bioenergetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract From anoxic sewage sludge a new strictly anaerobic, spore-forming bacterium was isolated with 2-hydroxybutyrate as sole substrate. 2-, 3-, and 4-hydroxybutyrate, 4-chlorobutyrate, crotonate, vinylacetate, and pyruvate were fermented to acetate and butyrate. Fructose was converted to acetate, butyrate, butanol, and H2. Lactate and acrylate were fermented to acetate and propionate. Cells pregrown with lactate fermented 2-hydroxybutyrate to butyrate, propionate and acetate. No inorganic electron acceptors were reduced. The DNA base ratio was 32.0±1.0 mol % and was similar to that of Clostridium propionicum, which was determined to be 35.3±0.5 mol %. Strain LuHBu1 is described as type strain of a new species, Clostridium homopropionicum sp. nov. Another isolate obtained from marine sediment degraded 2-and 3-hydroxybutyrate to acetate and butyrate and was in some respects similar to the known species Ilyobacter polytropus.
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  • 3
    ISSN: 1432-072X
    Keywords: Ilyobacter polytropus gen. nov. sp. nov. genus and species description ; Anaerobic degradation ; 3-Hydroxybutyrate ; Butyrate fermentation ; Propionate fermentation ; Ethanol fermentation ; Glycerol degradation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract From marine anoxic mud, a new strictly anaerobic, Gram-negative, non-sporeforming bacterium was isolated with 3-hydroxybutyrate as substrate. 3-Hydroxybutyrate and crotonate were fermented to acetate and butyrate. Glycerol was fermented to 1,3-propanediol and 3-hydroxypropionate. Acetate and formate were the only products of pyruvate or citrate fermentation. Glucose and fructose were fermented to acetate, formate and ethanol. Malate and fumarate were fermented to acetate, formate and propionate. Neither sulfate, sulfur, nor nitrate was reduced. The DNA base ratio was 32.2±0.5 mol% guanine plus cytosine. Strain CuHbu1 is described as type strain of a new genus and species, Ilyobacter polytropus gen. nov. sp. nov., in the family Bacteroidaceae.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 143 (1985), S. 52-59 
    ISSN: 1432-072X
    Keywords: Anaerobic phenol degradation ; Aromatic compounds ; Resorcinol ; Resorcylic acids ; Clostridium sp. ; Interspecies hydrogen transfer ; Butyrate fermentation ; Campylobacter sp.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Anaerobic fermentative degradation of resorcinol and resorcylates was studied in enrichment cultures inoculated with marine or freshwater sediments or digested sludge. α-Resorcylate (3,5-dihydroxybenzoate) was degraded very rapidly to acetate and methane by enrichment cultures inoculated with freshwater sediment or sewage sludge, but degradation was slow in enrichments from marine habitats. The freshwater cultures did not degrade any other related phenolic substrates. Inhibition of methanogenic bacteria by bromoethanesulfonate and acetylene led to enhanced acetate formation indicating homoacetogenic hydrogen oxidation. With resorcinol (1,3-dihydroxybenzene) and β- and γ-resorcylate (2,4- and 2,6-dihydroxybenzoate), two different types of Gram-positive spore-forming strict anaerobes were isolated, which both did not grow with α-resorcylate. Both were assigned to the genus Clostridium. From freshwater enrichments, six strains were isolated in defined coculture with Campylobacter sp. They fermented resorcinol and β- and γ-resorcylate stoichiometrically to acetate and butyrate. No interspecies hydrogen transfer to methanogenic or other anaerobic bacteria was found. None out of numerous organic nutrients tested substituted for Campylobacter sp. as partner in defined cultures; the nutritive dependence of this bacterium could not be elucidated. Isolates from marine sediments formed acetate and hydrogen from resorcyclic compounds, and depended on syntrophic association with hydrogenscavenging anaerobes such as methanogens.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 163 (1995), S. 188-194 
    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.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 158 (1992), S. 328-334 
    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.
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