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  • 1
    Electronic Resource
    Electronic Resource
    Pathways and regulation of N2, ammonium and glutamate assimilation by Clostridium formicoaceticum (1983)
    Springer
    Archives of microbiology 134 (1983), S. 167-169 
    Details
    ISSN: 1432-072X
    Keywords: Nitrogenase ; Glutamine synthetase ; Glutamate synthase ; Glutamate dehydrogenase ; Asparagine synthetase ; Alanine dehydrogenase ; β-Methylaspartase ; Clostridium formicoaceticum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Clostridium formicoaceticum possesses the following enzymes for the assimilation of N2 and NH 4 + : nitrogenase, glutamine synthetase, NADH- and NADPH-dependent glutamate synthase, NADH- and NADPH-dependent glutamate dehydrogenase, NADPH-dependent alamine dehydrogenase, and NH 4 + -dependent asparagine synthetase. Nitrogenase and glutamine synthetase are repressed and alanine dehydrogenase is induced by NH 4 + , while the synthesis of the other enzymes is not influenced by the extracellular NH 4 + level. Glutamate is degraded via glutamate mutase and β-methylaspartase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00407953
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Whole cell respiration and nitrogenase activities in Azotobacter vinelandii growing in oxygen controlled continuous culture (1983)
    Springer
    Archives of microbiology 134 (1983), S. 68-72 
    Details
    ISSN: 1432-072X
    Keywords: Azotobacter vinelandii ; Continuous culture ; Oxygen control ; Nitrogen fixation ; Respiratory protection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Azotobacter vinelandii strain OP was grown in continuous culture at various dissolved oxygen concentrations of air (100% air saturation of the medium=225 ±14 μM O2). Sucrose was added as carbon source and either dinitrogen or ammonia as nitrogen sources. Irrespective of the nitrogen source steady state cultures showed the following general responses with dissolved oxygen concentrations increasing from about 1% to 30% air saturation: (i) cell protein levels, (ii) the amount of cell protein formed per sucrose consumed as well as (iii) nitrogenase activity decreased by at least a factor of two while (iv) cellular respiration increased. At higher oxygen concentrations the parameters changed only slightly, if at all. Increasing the sucrose concentration in the inflowing medium (s R) from 3 g/l to 15 g/l increased the total level of cellular respiration with nitrogen-fixing cultures but was more pronounced with ammonium-assimilating cultures. With nitrogen-fixing cultures cell protein levels increased five-fold while the ratio of protein formed per sucrose consumed as well as cellular nitrogenase activity remained unaffected. With ammonium-assimilating cultures the cell protein level was only doubled and the level of cell protein formed per sucrose consumed was decreased at the higher s R. Increasing the dilution rate at a constant oxygen concentration of 45% air saturation resulted in an almost parallel increase of both cellular respiratory and nitrogenase activity at low and moderate dilution rates. At high dilution rates nitrogenase activity increased steeply over the respiratory activity. Nitrogen-fixing cultures adapted to various oxygen concentrations were subjected to oxygen stress by increasing the oxygen concentration for 7 min. In all cases, this resulted in a complete inhibition (‘switch-off’) of nitrogenase activity. Upon restoration of the original oxygen concentration nitrogenase activity returned to a decreased level. The discussion arrives at the conclusion that some of the results are incompatible with the concept of respiratory protection of nitrogenase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00429410
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Relative levels of guanosine 5′-diphosphate 3′-diphosphate (ppGpp) in some N2 fixing bacteria during derepression and repression of nitrogenase (1981)
    Springer
    Archives of microbiology 128 (1981), S. 341-342 
    Details
    ISSN: 1432-072X
    Keywords: Nitrogen fixation ; Regulation ; Guanosine 5′-diphosphate 3′-diphosphate (ppGpp)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Addition of ammonium to N2 fixing cultures of Azotobacter vinelandii, Klebsiella pneumoniae and Clostridium pasteurianum rapidly reduced the intracellular levels of guanosine 5′-diphosphate 3′-diphosphate (ppGpp) by 70–90%. This change might reflect a regulatory role of ppGpp in nitrogen metabolism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00422542
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  • 4
    Electronic Resource
    Electronic Resource
    Relationships between nitrogenase, glutamine synthetase, glutamine, and energy charge in Azotobacter vinelandii (1981)
    Springer
    Archives of microbiology 128 (1981), S. 412-415 
    Details
    ISSN: 1432-072X
    Keywords: Nitrogenase ; Glutamine synthetase ; Repression ; Amino acid pools ; Adenine nucleotide pools ; Azolobacter vinelandii
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract When continuous cultures of Azotobacter vinelandii were supplied with ammonium or nitrate in amounts, which just repressed nitrogenase synthesis completely, both the intracellular glutamine level and the degree of adenylylation of the glutamine synthetase (GS) increased only slightly (from 0.45–0.50 mM and from 2 to 3 respectively), while the total GS level remained unaffected. Higher amounts of ammonium additionally inhibited the nitrogenase activity, caused a strong rise in the intracellular glutamine concentration and adenylylation of the GS, but caused no change in the ATP/ADP ratio. These results are considered as evidence that in A. vinelandii the regulation of nitrogenase synthesis is not linked to the adenylylation state of the GS and to the intracellular glutamine level, and that the inhibition of the nitrogenase activity as a consequence of a high extracellular ammonium level is not mediated via a change in the energy charge.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00405923
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    Paper (German National Licenses)
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