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  • 1
    Electronic Resource
    Electronic Resource
    Energetics and regulations of formate and hydrogen metabolism by Methanobacterium formicicum (1993)
    Springer
    Archives of microbiology 159 (1993), S. 57-65 
    Details
    ISSN: 1432-072X
    Keywords: Methanobacterium formicicum ; Formate metabolism ; Methanogenesis from formate ; Methanogenesis from H2 ; H2 metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Accumulation of formate to millimolar levels was observed during the growth of Methanobacterium formicicum species on H2−CO2. Hydrogen was also produced during formate metabolism by M. formicicum. The amount of formate accumulated in the medium or the amount H2 released in gas phase was influenced by the bicarbonate concentration. The formate hydrogenlyase system was constitutive but regulated by formate. When methanogenesis was inhibited by addition of 2-bromoethane sulfonate, M. formicicum synthesized formate from H2 plus HCO inf3 sup- or produced H2 from formate to a steady-state level at which point the Gibbs free energy (ΔG′) available for formate synthesis or H2 production was approximately -2 to -3 kJ/reaction. Formate conversion to methane was inhibited in the presence of high H2 pressure. The relative rates of conversion of formate and H2 were apparently controlled by the ΔG′ available for formate synthesis, hydrogen production, methane production from formate and methane production from H2. Results from 14C-tracer tests indicated that a rapid isotopic exchange between HCOO- and HCO inf3 sup- occurred during the growth of M. formicicum on H2−CO2. Data from metabolism of 14C-labelled formate to methane suggested that formate was initially split to H2 and HCO inf3 sup- and then subsequently converted to methane. When molybdate was replaced with tungstate in the growth media, the growth of M. formicicum strain MF on H2−CO2 was inhibited although production of methane was not Formate synthesis from H2 was also inhibited.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00244265
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  • 2
    Electronic Resource
    Electronic Resource
    Environmental and physiological factors affecting the succinate product ratio during carbohydrate fermentation by Actinobacillus sp. 130Z (1997)
    Springer
    Archives of microbiology 167 (1997), S. 332-342 
    Details
    ISSN: 1432-072X
    Keywords: Key words Phosphoenolpyruvate ; Metabolic fluxes ; Fermentation ; Carbon dioxide fixation ; Fumarate ; reduction ; Succinate ; Actinobacillus sp. 130Z ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Actinobacillus sp. 130Z fermented glucose to the major products succinate, acetate, and formate. Ethanol was formed as a minor fermentation product. Under CO2-limiting conditions, less succinate and more ethanol were formed. The fermentation product ratio remained constant at pH values from 6.0 to 7.4. More succinate was produced when hydrogen was present in the gas phase. Actinobacillus sp. 130Z grew at the expense of fumarate and l-malate reduction, with hydrogen as an electron donor. Other substrates such as more-reduced carbohydrates (e.g., d-sorbitol) resulted in higher succinate and/or ethanol production. Actinobacillus sp. 130Z contained the key enzymes involved in the Embden-Meyerhof-Parnas and the pentose-phosphate pathways and contained high levels of phosphoenolpyruvate (PEP) carboxykinase, malate dehydrogenase, fumarase, fumarate reductase, pyruvate kinase, pyruvate formate-lyase, phosphotransacetylase, acetate kinase, malic enzyme, and oxaloacetate decarboxylase. The levels of PEP carboxykinase, malate dehydrogenase, and fumarase were significantly higher in Actinobacillus sp. 130Z than in Escherichia coli K-12 and accounted for the differences in succinate production. Key enzymes in end product formation in Actinobacillus sp. 130Z were regulated by the energy substrates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050452
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  • 3
    Electronic Resource
    Electronic Resource
    Isolation and characterization of Desulfovibrio growing on hydrogen plus sulfate as the sole energy source (1978)
    Springer
    Archives of microbiology 116 (1978), S. 41-49 
    Details
    ISSN: 1432-072X
    Keywords: Desulfovibrio ; Chemolithotrophic growth ; H2-Oxidation ; Sulfate-reduction ; Growth yields ; Cell carbon synthesis ; Acetate assimilation ; Desulfoviridin ; Cytochrome c3
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two sulfate reducing bacteria (Madison and Marburg strains) that grew on H2 plus sulfate in a mineral salts medium that contained acetate and CO2 as sole carbon source were isolated from diverse environments. During growth in this medium 4.2 mol of H2 were consumed per mol of sulfate reduced to sulfide. Acetate was required for biosynthetic purposes only. Approximately 70% of the cell carbon synthesized was derived from acetate and 30% from CO2. Acetate was not involved in dissimilatory sulfate reduction. Growth of the bacteria on H2 plus sulfate was linear rather than exponential, and a doubling time at the beginning of linear growth of approximately 3 h was observed. The optimal growth temperature was found to be near 35° C. Cultures could be grown up to a density of 500 mg cells (dry weight) per liter. Growth yield studies demonstrated that between 4 and 5 g of cells (dry weight) were formed per mol of sulfate reduced to sulfide. The chemolithotrophically growing sulfate reducing isolates were identified as Desulfovibrio species by being obligately anaerobic, gram negative, non spore forming vibrios that contained desulfoviridin and cytochrome c3 (350–450 nmol/g protein). The organisms were found to be monopolarly and monotrichously flagellated. The abilities of the two strains to grow on electron donors other than H2 and to use electron acceptors other than sulfate differed considerably. The DNA base composition of the Madison and Marburg strains were 60 and 63.5 mol % GC, respectively. The taxonomic status of the strains was discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00408732
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  • 4
    Electronic Resource
    Electronic Resource
    Purification and characterization of membrane-bound hydrogenase from Methanosarcina barkeri MS (1994)
    Springer
    Archives of microbiology 161 (1994), S. 47-54 
    Details
    ISSN: 1432-072X
    Keywords: Methanosarcina barkeri ; Hydrogenase — Membrane bound ; F420 nonreactive ; Cytochrome b ; Hydrogen uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Hydrogenase was solubilized from the membrane of acetate-grown Methanosarcina barkeri MS and purification was carried out under aerobic conditions. The enzyme was reactivated under reducing conditions in the presence of H2. The enzyme showed a maximal activity of 120±40 μmol H2 oxidized · min−1 · min−1 with methyl viologen as an electron acceptor, a maximal hydrogen production rate of 45±4 μmol H2 · min−1 · mg−1 with methyl viologen as electron donor, and an apparent K m for hydrogen oxidation of 5.6±1.7 μM. The molecular weight estimated by gel filtration was 98,000. SDS-PAGE showed the enzyme to consist of two polypeptides of 57,000 and 35,000 present in a 1:1 ratio. The native protein contained 8±2 mol Fe, 8±2 mol S2−, and 0.5 mol Ni/mol enzyme. Cytochrome b was reduced by hydrogen in a solubilized membrane preparation. The hydrogenase did not couple with autologous F420 or ferredoxin, nor with FAD, FMN, or NAD(P)+. The physiological function of the membrane-bound hydrogenase in hydrogen consumption is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00248892
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  • 5
    Electronic Resource
    Electronic Resource
    Crystallization and preliminary X-ray studies of Trp138Phe/Val185Thr xylose isomerases from Thermotoga neapolitana and Thermoanaerobacterium thermosulfurigenes (2001)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 57 (2001), S. 1686-1688 
    Details
    ISSN: 1399-0047
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Xylose isomerases from Thermotoga neapolitana (TNXI) and Thermoanaerobacterium thermosulfurigenes (TTXI) share 70.4% sequence identity and are thermostable. The double mutants Trp138Phe/Val185Thr of TNXI and TTXI have higher catalytic efficiencies than TNXI and TTXI, respectively. The Trp138Phe/Val185Thr TNXI and TTXI mutants were overexpressed in Escherichia coli strain BL21(DE3) and purified. Crystals of the two proteins were grown with polyethylene glycol 8000 as the major precipitant by the hanging-drop vapour-diffusion method. Crystals of the TNXI mutant were obtained in the absence of substrate, in complex with glucose and in complex with fructose. Crystals of the TTXI mutant were obtained complexed with glucose. Diffraction data were collected at 1.9, 2.1 and 2.1 Å resolution for the fructose–TNXI mutant, glucose–TNXI mutant and substrate-unbound TNXI mutant, respectively. The diffraction data for the glucose–TTXI mutant were collected at 2.0 Å resolution. The crystals belong to the orthorhombic space groups C2221 (TNXI mutant) and P212121 (TTXI mutant). The TNXI and TTXI mutant crystals contain two and four monomers in the asymmetric unit, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0907444901012835
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  • 6
    Electronic Resource
    Electronic Resource
    Microbial Decarboxylation of Succinate to Propionate (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 589 (1990), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1990.tb24282.x
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  • 7
    Electronic Resource
    Electronic Resource
    Thermal Stabilization of Xylose Isomerase from Thermoanaerobacterium thermosulfurigenes (1993)
    [s.l.] : Nature Publishing Company
    Nature biotechnology 11 (1993), S. 1157-1161 
    Details
    ISSN: 1546-1696
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: [Auszug] The thermostability of D-xylose isomerase from Thermoanaerobacterium thermosulfurigenes was enhanced by site-directed substitutions of aromatic amino acids in the active site. This enhancement may be explained as the consequence of the reduction of the area of water-accessible hydrophobic surface. ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nbt1093-1157
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  • 8
    Electronic Resource
    Electronic Resource
    Physiological and enzymatic characterization of a novel pullulan-degrading thermophilic Bacillus strain 3183 (1990)
    Springer
    Applied microbiology and biotechnology 33 (1990), S. 340-344 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary A new thermophilic Bacillus strain 3183 (ATCC 49341) was isolated from hot-spring sediments. The organism grew on pullulan as a carbon source and showed optimum pH and temperature at pH 5.5 and 62° C, respectively, for growth. The strain reduced nitrate to nitrite both aerobically and anaerobically. It produced extracellular thermostable pullulanase and saccharidase activities which degraded pullulan and starch into maltotriose, maltose, and glucose. Medium growth conditions for pullulanase production were optimized. The optimum pH and temperature for pullulanase activity were at pH 6.0 and 75° C, respectively. The enzyme was stable at pH 5.5-7.0 and temperature up to 70° C in the absence of substrate. The K m for pullulan at pH 6.0 and 75° C was 0.4 mg/ml. The pullulanase activity was stimulated and stabilized by Ca2+. It was inhibited by ethylenediaminetetraacetate (EDTA), beta and gamma-cyclodextrins but not by alpha-cyclodextrin and reagents that inhibit essential enzyme SH-groups.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00164533
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  • 9
    Electronic Resource
    Electronic Resource
    Metabolic properties and kinetics of methanogenic granules (1993)
    Springer
    Applied microbiology and biotechnology 39 (1993), S. 804-811 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Two types of mesophilic methanogenic granules (R- and F-granules) were developed on different synthetic feeds containing acetate, propionate and butyrate as major carbon sources and their metabolic properties were characterized. The metabolic activities of granules on acetate, formate and H2-CO2 were related to the feed composition used for their development. These granules performed a reversible reaction between H2 production from formate and formate synthesis from H2 plus bicarbonate. Both types of granules exhibited high activity on normal and branched volatile fatty acids with three to five carbons and low activity on ethanol and glucose. The granules performed a reversible isomerization between isobutyrate and butyrate during butyrate or isobutyrate degradation. Valerate and 2-methylbutyrate were produced and consumed during propionate-butyrate degradation. The respective apparent K m (mm) for various substrates in disrupted R- and F-granules was: acetate, 0.43 and 0.41; propionate, 0.056 and 0.038; butyrate, 0.15 and 0.19; isobutyrate, 0.12 and 0.19; valerate, 0.15 and 0.098. Both granules had an optimum temperature range from 40 to 50° C for H2-CO2 and formate utilization and 40° C for acetate, propionate and butyrate utilization and a similar optimum pH.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00164470
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  • 10
    Electronic Resource
    Electronic Resource
    Improved purification and biochemical characterization of extracellular amylopullulanase from Thermoanaerobacter ethanolicus 39E (1993)
    Springer
    Applied microbiology and biotechnology 39 (1993), S. 487-493 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A maltose-limited chemostat culture was used to investigate the expression and excretion of amylopullulanase by Thermoanaerobacter ethanolicus 39E (formerly Clostridium thermohydrosulfuricum 39E). In maltose-limited continuous culture, amylopullulanase was produced and secreted at tenfold higher levels than in batch culture. The extracellular amylopullulanase was purified to homonogeneity by using an inhibitor-linked affinity column matrix. The purified amylopullulanase had a specific activity of 480 units (U)/mg protein for pullulanase and 175 U/mg protein for α-amylase. β-Cyclodextrin inhibited both α-amylase and pullulanase activities, with a substrate inhibition constant (K i) of 0.065 mg/ml.Amylopullulanase had a relative molecular mass (Mr) of 140 000 using sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis and an Mr of 133 000 using gel-filtration chromatography. The N-terminal sequence of the enzyme was Glu-Thr-Asp-Thr-Ala-Pro-Ala. The purified enzyme displayed Michaelis constant (K m) values of 0.35 mg/ml for pullulan and 1.00 mg/ml for amylose. The enzyme had an isoelectric point (pI) of 4.0, and displayed an optimum pH for stability and activity of 6.2 and 5.5, respectively. The enzyme was stable up to 85° C in the presence of Ca2+, and had a half-life of 40 min at 90° C (pH 6.2). Ca2+ was required for thermal stability, but not for activity. Amylose, glycogen, and amylopectin were degrade to maltose, maltotriose, and maltotetraose, whereas only maltotriose was formed from pullulan.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00205038
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