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  • 1
    Digitale Medien
    Digitale Medien
    Possible evolutionary relationships of the nitrogenase proteins (1976)
    Springer
    Journal of molecular evolution 7 (1976), S. 159-165 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Nitrogenases ; ATP-ases ; Amino Acid Compositions ; S△Q ; Evolutionary Relationships
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Comparisons of the amino acid compositions of the nitrogenase proteins from different organisms and their correlation with cross-reactivities and taxonomical data suggest an evolution within bacterial genomes rather than within plasmids. Comparisons of the amino acid compositions of nitrogenases and other ATP-ases show similarities which might be due to the evolution of these ATP-ases from a common ancestral protein.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01732473
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  • 2
    Digitale Medien
    Digitale Medien
    Nodulation pattern and acetylene reduction (nitrogen fixation) activity of some highland and lowland Acacia species of Ethiopia (1998)
    Springer
    Biology and fertility of soils 27 (1998), S. 60-64 
    Details
    ISSN: 1432-0789
    Schlagwort(e): Key words Acacia spp. ; Bradyrhizobium ; Rhizobium ; Nitrogen fixation ; Nitrogen accumulation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Geologie und Paläontologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract  Endosymbionts from the Ethiopian highland acacia species Acacia abyssinica, A. negrii and A. etbaica, and the lowland species A. nilotica, A. prasinata, A.senegal, A. seyal, A. tortilis and Faidherbia (Acacia) albida were isolated and characterized. Seven tree species were found to be nodulated by species of both Rhizobium and Bradyrhizobium. F. (Acacia) albida and A. senegal were nodulated by only Bradyrhizobium or Rhizobium, respectively. In A. abyssinica, both genera were isolated from the same nodule, whereas in A. nilotica and A. tortilis, both strains were isolated from different nodules of the same plant. The nitrogen fixation (acetylene reduction) activities varied considerably and showed no correlation with the nitrogen content of the plant. Highland species were as effective as lowland plants, thus demonstrating good potential for soil reclamation. The endosymbionts isolated proved rather promiscuous, efficiently nodulating other Acacia spp. and some tropical grain legumes, but did not nodulate temperate legumes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s003740050400
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  • 3
    Digitale Medien
    Digitale Medien
    Applicability of arginine ammonification as indicator of microbial activity in different soils (1987)
    Springer
    Biology and fertility of soils 5 (1987), S. 148-151 
    Details
    ISSN: 1432-0789
    Schlagwort(e): Arginine ammonification ; Respiration ; Microbial activity estimation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Geologie und Paläontologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Amendment of soils with arginine resulted in immediate liberation of ammonia. The rate was linear for several hours, and was strongly reduced by toluene treatment or under anaerobic conditions. Together with a strong stimulation of respiration by arginine these results demonstrate that arginine ammonification is due to living microorganisms. Arginine ammonification was strongly related to respiration and correlated significantly with the carbon content of the soil, but not or only poorly with soil pH, ammonia content, percentage clay or the number of microorganisms.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00257650
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  • 4
    Digitale Medien
    Digitale Medien
    Ammonium uptake by nitrogen fixing bacteria (1975)
    Springer
    Archives of microbiology 104 (1975), S. 163-169 
    Details
    ISSN: 1432-072X
    Schlagwort(e): Azotobacter vinelandii ; Nitrogenase ; Glutamine Synthetase ; Ammonium Pool ; Ammonium Transport ; Citrate Transport ; Repression
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Both the changes in the activities of nitrogenase, glutamine synthetase and glutamate dehydrogenase and in the extracellular and intracellular NH4 + concentrations were investigated during the transition from an NH4 + free medium to one containing NH4 + ions for a continuous culture of Azotobacter vinelandii. If added in amounts causing 80–100% repression of nitrogenase, ammonium acetate, lactate and phosphate are absorbed completely, whereas chloride, sulfate and citrate are only taken up to about 80%. After about 1–2 hrs the NH4 + remaining in the medium is absorbed too, indicating the induction or activation of a new NH4 + transport system. One of the new permeases allows the uptake of citrate in the presence of sucrose. Addition of inorganic NH4 + salts leads to acidification of the culture. Anaerobiosis suppresses NH4 + transport. A rise in the extracellular NH4 + level leads to a reversible rise in the glutamine synthetase activity, which is not prevented by chloramphenicol, and to a reversible decrease in nitrogenase activity. During these measurements glutamate dehydrogenase activity remains close to zero. The intracellular NH4 + level of about 0.6 mM does not change when extracellular NH4 + is taken up and repression of nitrogenase starts.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00447319
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  • 5
    Digitale Medien
    Digitale Medien
    Ammonia-excreting mutants of Klebsiella pneumoniae with a pleiotropic defect in nitrogen metabolism (1997)
    Springer
    Archives of microbiology 166 (1997), S. 388-393 
    Details
    ISSN: 1432-072X
    Schlagwort(e): Key words Ammonium metabolism ; glnAntrBC ; Nitrogenase regulation ; Nitrogen control ; Ammonia ; excretion ; Amino acid utilization ; Ntr
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Enterobacterial mutants defective in the nitrogen control regulatory system (Ntr) generally display a pleiotropic phenotype with regard to expression and regulation of several enzymes and transport systems involved in the assimilation of N sources. This report describes the isolation and characterization of similar pleiotropic mutants of Klebsiella pneumoniae that cannot be complemented by ntr genes. The strains excreted ammonia, were unable to grow on a number of N sources, and contained low glutamine:2-oxoglutarate amino transferase and normal, but unmodifiable glutamine synthetase activities and a nitrogenase level largely unaffected by ammonium, but still repressible by an amino acid mixture. Genetic studies suggested that this phenotype is due to overexpression of an unknown regulatory protein.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01682984
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  • 6
    Digitale Medien
    Digitale Medien
    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
    Schlagwort(e): Nitrogenase ; Glutamine synthetase ; Glutamate synthase ; Glutamate dehydrogenase ; Asparagine synthetase ; Alanine dehydrogenase ; β-Methylaspartase ; Clostridium formicoaceticum
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00407953
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  • 7
    Digitale Medien
    Digitale Medien
    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
    Schlagwort(e): Azotobacter vinelandii ; Continuous culture ; Oxygen control ; Nitrogen fixation ; Respiratory protection
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00429410
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  • 8
    Digitale Medien
    Digitale Medien
    Interrelationship between hydrogen peroxide, ammonia, glutamine, hydroxylamine and nitrite metabolism in the cyanobacterium Phormidium uncinatum (1991)
    Springer
    Archives of microbiology 156 (1991), S. 367-369 
    Details
    ISSN: 1432-072X
    Schlagwort(e): Phormidium uncinatum ; Hydrogen peroxide production ; Nitrification ; Ammonia oxidation ; Hydroxylamine metabolism ; Detoxification
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract On transition from nitrogen starvation to ammonia or ammonia/glutamine sufficiency Phormidium uncinatum produces high amounts of H2O2, which is consumed by several oxidative reactions catalyzed by thylakoid membrane bound enzymes. These include: oxidation of glutamine to free hydroxylamine, of ammonia to nitrite, of bound hydroxylamine to nitrite, and dismutation of free hydroxylamine to ammonia and nitrite. A possible role of these transformations for detoxification is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00248712
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  • 9
    Digitale Medien
    Digitale Medien
    Regulation of ammonium uptake and metabolism by nitrogen fixing bacteria. III. Clostridium pasteurianum (1979)
    Springer
    Archives of microbiology 120 (1979), S. 263-270 
    Details
    ISSN: 1432-072X
    Schlagwort(e): Enzyme regulation ; Ammonium metabolism ; Nitrogenase ; Glutamine synthetase ; Glutamate synthase ; Glutamate dehydrogenase ; Asparagine synthetase ; Amino acid pools ; Clostridium pasteurianum
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Addition of ammonium salts to N2 fixing continuous cultures of Clostridium pasteurianum caused immediate stop of nitrogenase synthesis, while the levels of glutamine synthetase, glutamate dehydrogenase and asparagine synthetase remained constant. No evidence for an interconversion of the glutamine synthetase was found. The activities of glutamate synthase in crude extracts were inversely related to the nitrogenase levels. The intracellular glutamine pool rapidly expanded during nitrogenase repression and decreased as fast during derepression while the pool sizes of all other amino acids were not strongly related to the rate of nitrogenase formation. These investigations suggest glutamine as corepressor of nitrogenase synthesis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00423074
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  • 10
    Digitale Medien
    Digitale Medien
    Characterization of a Paracoccus denitrificans mutant pleiotropically impaired in nitrogen metabolism (1993)
    Springer
    Archives of microbiology 160 (1993), S. 166-168 
    Details
    ISSN: 1432-072X
    Schlagwort(e): Paracoccus denitrificans ; Ammonia assimilation pathways ; Nitrogen catabolism regulation ; Ammonium transport ; Glutamine synthetase ; Glutamate synthase ; Aminotransferase
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A Tn5 insertional prototrophic mutant of Paracoccus denitrificans (UBM219) was generated which grew on high (〉1 mM) but not low (〈0.5 mM) ammonium as sole nitrogen source. It did not utilize nitrate and most amino acids except glutamate and aspartate. UBM219 showed more than 10-fold lower levels of ammonium (methylammonium) transport, aspartate and alanine aminotransferase, but more than 10-fold higher activities of glutamate dehydrogenase and glutamate synthase. This pleiotropy indicates a mutation in a regulatory gene affecting nitrogen metabolism in general. — Ammonia assimilation pathways and regulation in Paracoccus resemble the patterns in enterobacteria with the exception, that alanine is generated by amino transfer from glutamate to pyruvate.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00288721
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