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  • Methanobacterium thermoautotrophicum  (5)
  • Pyruvate fermentation  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Pyruvate — a novel substrate for growth and methane formation in Methanosarcina barkeri (1994)
    Springer
    Archives of microbiology 161 (1994), S. 33-46 
    Details
    ISSN: 1432-072X
    Keywords: Methanosarcina barkeri ; Pyruvate-utilizing mutant ; Methanogenesis ; Archaea ; Pyruvate fermentation ; Acetate fermentation ; Growth yields (Y ch4 ) ; Ferredoxin ; Pyruvate: ferredoxin oxidoreductase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Methanosarcina barkeri strain Fusaro was found to grow on pyruvate as sole carbon and energy source after an incubation period of 10–12 weeks in the presence of high pyruvate concentrations (100 mM). Growth studies, cell suspension experiments and enzymatic investigations were performed with pyruvate-utilizing M. barkeri. For comparison acetate-adapted cells of M. barkeri were analyzed. 1. Pyruvate-utilizing M. barkeri grew on pyruvate (100 mM) with an initial doubling time of about 25 h (37 °C, pH 6.5) up to cell densities of about 0.8 g cell dry weight/l. The specific growth rate was linearily dependent on the pyruvate concentration up to 100 mM indicating that pyruvate was taken up by passive diffusion. Only CO2 and CH4 were detected as fermentation products. As calculated from fermentation balances pyruvate was converted to CH4 and CO2 according to following equation: Pyruvate-+H++0.5 H2O » 1.25 CH4+1.75 CO2. The molar growth yield (Ych 4) was about 14 g dry weight cells/mol CH4. In contrast the growth yield (Ych 4) of M. barkeri during growth on acctate (Acetate-+H+ » CH4+CO2) was about 3 g/mol CH4. 2. Cell suspensions of pyruvate-grown M. barkeri catalyzed the conversion of pyruvate to CH4, CO2 and H2 (5–15 nmol pyruvate consumed/min x mg protein). At low cell concentrations (0.5 mg protein/ml) 1 mol pyruvate was converted to 1 mol CH4, 2 mol CO2 and 1 mol H2. At higher cell concentration less H2 and CO2 and more CH4 were formed due to CH4 formation from H2/CO2. The rate of pyruvate conversion was linearily dependent on the pyruvate concentration up to about 30 mM. Cell suspensions of acetate-grown M. barkeri also catalyzed the conversion of 1 mol pyruvate to 1 mol CH4, 2 mol CO2 and 1 mol H2 at similar rates and with similar affinity for pyruvate as pyruvate-grown cells. 3. Cell extracts of both pyruvate-grown and acetate-grown M. barkeri contained pyruvate: ferredoxin oxidoreductase. The specific activity in pyruvate-grown cells (0.8 U/mg) was 8-fold higher than in acetate-grown cells (0.1 U/mg). Coenzyme F420 was excluded as primary electron acceptor of pyruvate oxidoreductase. Cell extracts of pyruvate-grown M. barkeri contained carbon monoxide dehydrogenase activity and hydrogenase activity catalyzing the reduction by carbon monoxide and hydrogen of both methylviologen and ferredoxin (from Clostridium). This is the first report on growth of a methanogen on pyruvate as sole carbon and energy source, i.e. on a substrate more complex than acetate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00248891
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  • 2
    Electronic Resource
    Electronic Resource
    Potassium accumulation in growing Methanobacterium thermoautotrophicum and its relation to the electrochemical proton gradient (1984)
    Springer
    Archives of microbiology 140 (1984), S. 247-251 
    Details
    ISSN: 1432-072X
    Keywords: Methanobacterium thermoautotrophicum ; Potassium accumulation ; Membrane potential ; pH gradient ; Energy coupling ; Active transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cultures of Methanobacterium thermoautotrophicum (Marburg) growing on media low in potassium accumulated the cation up to a maximal concentration gradient ([K+]intracellular/[K+]extracellular) of approximately 50,000-fold. Under these conditions, the membrane potential was determined by measuring the equilibrium distribution of the lipophilic cation (14C) tetraphenylphosphonium (TPP+). This cation was accumulated by the cells 350-to 1,000-fold corresponding to a membrane potential (inside negative) of 170–200 mV. The pH gradient, as measured by equilibrium distribution of the weak acid, benzoic acid, was found to be lower than 0.1 pH units (extracellular pH=6.8). The addition of valinomycin (0.5–1 nmol/mg cells) to the culture reduced the maximal concentration gradient of potassium from 50,000-to approximately 500-fold, without changing the membrane potential. After dissipation of the membrane potential by the addition of 12C-TTP+ (2 μmol/mg cells) or tetrachlorosalicylanilide (3 nmol/mg cells), a rapid and complete efflux of potassium was observed. These data indicate that potassium accumulation in the absence of valinomycin is not in equilibrium with the membrane potential. It is concluded that at low extracellular K+ concentrations potassium is not accumulated by M. thermoautotrophicum via an electrogenic uniport mechanism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00454936
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  • 3
    Electronic Resource
    Electronic Resource
    Presence of a Na+/H+ antiporter in Methanobacterium thermoautotrophicum and its role in Na+ dependent methanogenesis (1985)
    Springer
    Archives of microbiology 142 (1985), S. 354-361 
    Details
    ISSN: 1432-072X
    Keywords: Methanobacterium thermoautotrophicum ; Na+ dependent methanogenesis ; Na+/H+ antiporter ; pH regulation ; Membrane potential ; pH gradient
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Methane formation from H2/CO2 by methanogenic bacteria is dependent on Na+ ions. In this communication it is shown with Methanobacterium thermoautotrophicum that a Na+/H+ antiporter plays a role in methane formation from H2 and CO2 and in the regulation of the ΔpH. This is based on the following findings: (i) Li+ ions, an alternative substrate of Na+/H+ antiporters, could replace Na+ in stimulating methanogenesis from H2 and CO2. (ii) Harmaline, amiloride, and NH 4 + , which are inhibitors of Na+/H+ antiporters, inhibited methanogenesis; inhibition was competitive to Na+ or Li+. (iii) Addition of Na+ or Li+ rather than of other cations to cell suspensions resulted in an acidification of the suspension medium. The rate and extent of acidification was affected by those inhibitors, which inhibited methanogenesis competitively to Na+ or Li. (iv) During methane formation from H2 and CO2 the generation of a ΔpH (inside alkaline) was dependent on the presence of Na+ or Li+. However, methanogenesis was also dependent on Na+ or Li+ under conditions where ΔpH was zero. (v) ATP synthesis driven by an electrogenic potassium efflux was significantly enhanced in the presence of Na+ or Li+. Na+ or Li+ were shown to prevent acidification of the cytoplasm under these conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00491903
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  • 4
    Electronic Resource
    Electronic Resource
    Pyruvate metabolism of the hyperthermophilic archaebacterium Pyrococcus furiosus (1991)
    Springer
    Archives of microbiology 155 (1991), S. 366-377 
    Details
    ISSN: 1432-072X
    Keywords: Pyrococcus furiosus ; Hyperthermophilic archabacteria ; Pyruvate fermentation ; Growth yields ; Hydrogen inhibition ; Sulfur stimulation ; Pyruvate:ferredoxin oxidoreductase ; Acetyl-CoA synthetase (ADP forming) ; Adenylate kinase ; ATPase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The hyperthermophilic anaerobe Pyrococcus furiosus was found to grow on pyruvate as energy and carbon source. Growth was dependent on yeast extract (0.1%). The organism grew with doublings times of about 1 h up to cell densities of 1–2×108 cells/ml. During growth 0.6–0.8 mol acetate and 1.2–1.5 mol CO2 and 0.8 mol H2 were formed per mol of pyruvate consumed. The molar growth yield was 10–11 g cells(dry weight)/mol pyruvate. Cell suspensions catalyzed the conversion of 1 mol of pyruvate to 0.6–0.8 mol acetate, 1.2–1.5 mol CO2, 1.2 mol H2 and 0.03 mol acetoin. After fermentation of [3-14C]pyruvate the specific radioactivities of pyruvate, CO2 and acetate were equal to 1:0.01:1. Cellfree extracts contained the following enzymatic activities: pyruvate: ferredoxin (methyl viologen) oxidoreductase (0.2 U mg-1, T=60°C, with Clostridium pasteurianum ferredoxin as electron acceptor; 1.4 U mg-1 at 90°C, with methyl viologen as electron acceptor); acetyl-CoA synthetase (ADP forming) [acetyl-CoA+ADP+Pi⇆acetate+ATP+CoA] (0.34 U mg-1, T=90°C), and hydrogen: methyl viologen oxidoreductase (1.75 U mg-1). Phosphate acetyl-transferase activity, acetate kinase activity, and carbon monoxide:methyl viologen oxidoreductase activity could not be detected. These findings indicate that the archaebacterium P. furiosus ferments pyruvate to acetate, CO2 and H2 involving only three enzymes, a pyruvate:ferredoxin oxidoreductase, a hydrogenase and an acetyl-CoA synthetase (ADP forming).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00243457
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  • 5
    Electronic Resource
    Electronic Resource
    Growth parameters (K s, μmax, Y s) of Methanobacterium thermoautotrophicum (1980)
    Springer
    Archives of microbiology 127 (1980), S. 59-65 
    Details
    ISSN: 1432-072X
    Keywords: Methanobacterium thermoautotrophicum ; Growth rates ; Growth yields ; Nickel ; Maintenance coefficient ; Interspecies hydrogen transfer ; Saturation constants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Methanobacterium thermoautotrophicum was grown on a mineral salts medium in a fermenter gassed with H2 and CO2, which were the sole carbon and energy sources. Under the conditions used the bacterium grew exponentially. The dependence of the growth rate (μ) on the concentration of H2 and CO2 in the incoming gas and the dependence of the growth yield ( $$Y_{CH_4 }$$ ) on the growth rate were determined at pH 7 (the pH optimum) and 65° C (the temperature optimum). The curves relating growth rate to the H2 and CO2 concentration were hyperbolic. From reciprocal plots apparent K s values for H2 and CO2 and μmax were obtained: app. $$K_{{\text{H}}_{\text{2}} }$$ = 20%; app. $$K_{{\text{CO}}_{\text{2}} }$$ = 11%; μ = 0.69 h-1; t δ (max)=1 h. $$Y_{CH_4 }$$ was 1.6 g mol-1 and almost independent of the growth rate, when the rate of methane formation was not limited by the supply of either H2 or CO2. The yield increased to near 3 g mol-1 when H2 or CO2 were limiting. These findings indicate that methane formation and growth are less tightly coupled at high concentrations of H2 or CO2 in the medium than at low concentrations. The physiological significance of these findings is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00414356
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  • 6
    Electronic Resource
    Electronic Resource
    Nickel, cobalt, and molybdenum requirement for growth of Methanobacterium thermoautotrophicum (1979)
    Springer
    Archives of microbiology 123 (1979), S. 105-107 
    Details
    ISSN: 1432-072X
    Keywords: Nickel ; Cobalt ; Molybdenum ; Iron ; Methanobacterium thermoautotrophicum ; Trace elements
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Growth of Methanobacterium thermoautotrophicum on H2 and CO2 as sole energy and carbon sources was found to be dependent on Ni, Co, and Mo. At low concentrations of Ni (〈100 nM), Co (〈10 nM) and Mo (〈10 nM) the amount of cells formed was roughly proportional to the amount of transition metal added to the medium; for the formation of 1 g cells (dry weight) approximately 150 nmol NiCl2, 20 nmol CoCl2 and 20 nmol Na2MoO4 were required. A dependence of growth on Cu, Mn, Zn, Ca, Al, and B could not be demonstrated. Conditions are described under which the bacterium grew exponentially with a doubling time of 1.8 h up to a cell density of 2 g cells (dry weight)/1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00403508
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  • 7
    Electronic Resource
    Electronic Resource
    Studies on the biosynthesis of coenzyme F420 in methanogenic bacteria (1984)
    Springer
    Archives of microbiology 137 (1984), S. 362-365 
    Details
    ISSN: 1432-072X
    Keywords: Coenzyme F420 ; Flavin biosynthesis ; Deazaflavins ; Guanine assimilation ; Methanogenic bacteria ; Methanobacterium thermoautotrophicum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Coenzyme F420 is a 8-hydroxy-5-deazaflavin present in methanogenic bacteria. We have investigated whether the pyrimidine ring of the deazaflavin originates from guanine as in flavin biosynthesis, in which the pyrimidine ring of guanine is conserved. For this purpose the incorporation of [2-14C]guanine and of [8-14C]guanine into F420 by growing cultures of Methanobacterium thermoautotrophicum was studied. Only in the case of [2-14C]guanine did F420 become labeled. The specific radioactivity of the deazaflavin and of guanine isolated from nucleic acids of [2-14C]guanine grown cells were identical. This finding suggests that the pyrimidine ring of the deazaflavin and of flavins are synthesized by the same pathway. F420 did not become labeled when M. thermoautotrophicum was grown in the presence of methyl-[14C] methionine, [U-14C]phenylalanine or [U-14C]tyrosine. This excludes that C-5 of the deazaflavin is derived from the methyl group of methionine and that the benzene ring comes from phenylalanine or tyrosine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00410735
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