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  • Regulation  (84)
  • Methanobacterium thermoautotrophicum  (54)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 112 (1977), S. 283-285 
    ISSN: 1432-072X
    Keywords: Wine yeasts ; Sulfur metabolism ; Regulation ; Sulfate uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Five different strains of wine yeasts were investigated with respect to active uptake of [35S] sulfate and its regulation by methionine. Considerable differences exist between “low” and “high” sulfite-producing strains in the initial velocity of sulfate uptake. Further differences were established in repression of sulfate permease by l-methionine, most evident in a total lack of repression in one of the “high” sulfite producers. These findings explain in part variable sulfite and sulfide formation.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-072X
    Keywords: cAMP ; Regulation ; Chlorophyll synthesis ; Chlorella fusca
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The intracellular concentration of cAMP in the green alga Chlorella fusca was in the range of 2 · 10-9 to 10-8 moles/g dry weight and was strongly dependent on the growth conditions. The cAMP level was high with high light intensity, low nitrate or glucose concentration. Intracellular cAMP increased only by factor of 2 when high amounts (up to 10-3 M) of cAMP were added to the medium. Most of the given cAMP was converted to 5′-AMP. Addition of cAMP had little effect on the chlorophyll content of the cells, only at 10-6 M some enhancement in photoautotrophic cultures was observed. On the other hand high amounts of cAMP in the medium increased the growth rate. DBcAMP* showed a positive effect on chlorophyll synthesis and growth rate at much lower concentrations compared to cAMP. Stimulation effects of exogenous cAMP on the synthesis of chlorophyll were also observed in mixotrophic cultures with a high glucose/nitrate ratio, conditions where chlorophyll synthesis is repressed. Similar to autotrophic conditions DBcAMP was more effective than cAMP. These data indicate that cAMP may act in a system controlling the chlorophyll content of the cells in response to nutrients or light.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-072X
    Keywords: Root nodule symbiosis ; Rhizobium meliloti ; Medicago sativa ; Nitrogenase activity ; Regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Symbiotic nitrogen fixation of Rhizobium meliloti bacteroids in Medicago sativa root nodules was suppressed by several inorganic nitrogen sources. Amino acids like glutamine, glutamic acid and aspartic acid, which can serve as sole nitrogen sources for the unnodulated plant did not influence nitrogenase activity of effective nodules, even at high concentrations. Ammonia and nitrate suppressed symbiotic nitrogen fixation in vivo only at concentrations much higher than those needed for suppression of nitrogenase activity in free living nitrogen fixing bacteria. The kinetics of suppression were slow compared with that of free living nitrogen fixing bacteria. On the other hand, nitrite, which acts as a direct inhibitor of nitrogenase, suppressed very quickly and at low concentrations. Glutamic acid and glutamine enhanced the effect of ammonia dramatically, while the suppression by nitrate was enhanced only slightly.
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  • 4
    ISSN: 1432-072X
    Keywords: Physarum polycephalum ; Amoebae ; Aminopeptidases ; Acid proteases ; Regulation ; Development ; Differential gene activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The cultivation of Physarum polycephalum amoebae in two media with different protein contents revealed a regulation of aminopeptidases and proteases depending on the albumin content of the medium: in growing amoebae and plasmodia the aminopeptidases have similar isoenzyme patterns and relative activities against nitroanilides. One alanine and four leucine aminopeptidase isoenzymes were found within the slightly acid pH range. During growth amoebae secrete—different from plasmodia—leucine aminopeptidase into the medium with low protein content. In an albumin-rich medium additional alanine aminopeptidase activity was found. Out of nine plasmodial proteases four were found in amoebae too. Only one band (pI 3.6) was present in the protein-poor medium. No protease activity could be detected in the proteinrich medium.
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  • 5
    ISSN: 1432-072X
    Keywords: Methanobacterium thermoautotrophicum ; Autotrophic CO2 fixation ; Reductive carboxylic acid cycle ; α-ketoglutarate synthase ; Amino acid synthesis ; Carboxylation reactions ; Succinate incorporation ; Citrate lyase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The involvement of reactions of the tricarboxylic acid cycle in autotrophic CO2 fixation in Methanobacterium thermoautotrophicum was investigated. The incorporation of succinate into glutamate (=α-ketoglutarate), aspartate (=oxaloacetate) and alanine (=pyruvate) was studied. The organism was grown on H2 plus CO2 at pH 6.5 in the presence of 1 mM [U-14C-]succinate. Significant amounts of the dicarboxylic acid were incorporated into cellular material under these conditions. Alanine, aspartate, and glutamate were isolated and their specific radioactivities were determined. Only glutamate was found to be labelled. Degradation of glutamate revealed that C-1 of glutamate was derived from CO2 and C-2-C-5 from succinate indicating that in M. thermoautotrophicum α-ketoglutarate is synthesized via reductive carboxylation of succinyl CoA. The finding that succinate was not incorporated into alanine and aspartate excludes that oxaloacetate and pyruvate are synthesized from α-ketoglutarate via isocitrate or citrate. This is taken as evidence that a complete reductive carboxylic acid cycle is not involved here in autotrophic CO2 fixation.
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  • 6
    ISSN: 1432-072X
    Keywords: Methanobacterium formicicum ; Methanobacterium thermoautotrophicum ; Methanobacterium ruminantium ; Methanobacterium arbophilicum ; Methanobacterium sp. M. o. H. ; Methanobacterium mobile ; Methanococcus ; Methanospirillum hungatii ; Cell wall polymer ; Cell wall composition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cell walls were prepared from freeze-dried samples of 7 strains of Methanobacterium by mechanical disintegration of the cells followed by incubation with trypsin. Electron microscopy revealed the presence of sacculi exhibiting the shape of the original cells, on which no surface structure could be detected. Ultrathin sections of the isolated sacculi showed a homogenously electron dense layer of about 10–15 nm in width. The ash content varied between 8 and 18% of dry weight. The sacculi of all the strains contained Lys: Ala: Glu: GlcNAc or GalNAc in a molar ratio of about 1:1.2:2:1. In one strain (M. ruminantium M 1) alanine is replaced by threonine, however. Neutral sugars and-in some strains-additional amounts of the amino sugars were present in variable amounts, and could be removed by formamide extraction or HF treatment without destroying the sacculi. No muramic acid or d-amino acids typical of peptidoglycan were found. Therefore, the sacculi of the methanobacteria consist of a different polymer containing a set of three l-amino acids and one N-acetylated amino sugar. From cells of Methanospirillum hungatii no sacculi, but tube-like sheaths could be isolated, which tend to fracture perpendicularly to the long axis of the sheath along the fibrills seen on the surface. The sheaths consist of protein containing 18 amino acids and small amounts of neutral sugars. They are resistent to the proteinases tested and are not disintegrated by boiling in 2% sodium dodecylsulfate for 30 min. The three Gram-negative strains Black Sea isolate JR-1, Cariaco isolate JR-1 and Methanobacterium mobile do not contain a rigid sacculus, but merely a SDS-sensitive surface layer composed of regularly arranged protein subunits. This evidence indicates that, within the methanogens, different cell wall polymers characteristic of particular groups of organisms may have evolved during evolution, and supports the hypothesis that the evolution of the methanogens was separated from that of the peptidoglycan-containing procaryotic organisms at a very early stage.
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  • 7
    ISSN: 1432-072X
    Keywords: Streptococcus cremoris ; Cell wall proteinase ; Calcium dependency ; Regulation ; Translational control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The persistent accumulation of proteinase (PIII) activity in the cell wall of Streptococcus cremoris strain AM1 during growth depends on the presence of Ca2+-ions in the medium. In the absence of calcium initial accumulation of activity in the cell wall is observed, followed by a decrease to a low final level. Under this condition no increase of proteolytic activity is found in the extracellular fluid. A possible function of calcium in the stabilization of the enzyme is discussed. Prolonged accumulation of catalytically active proteinase PIII in the cell wall occurs in the absence of messenger ribonucleic acid synthesis. This process involves de novo protein synthesis supported by preformed proteinase-specific messenger ribonucleic acid, which is possibly either intrinsically long-lived or is stabilized following its transcription. The level of the extracellular concentration of amino acids and/or peptides regulates the translation of newly synthesized proteinase-specific messenger ribonucleic acid and, possibly, the growth of the organism in milk.
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  • 8
    ISSN: 1432-072X
    Keywords: Methanobacterium thermoautotrophicum ; Cell wall ; Pseudomurein ; Amino acid sequence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The amino acid sequence of the peptide subunits of the peptide moiety of the sacculus polymer (pseudomurein) of Methanobacterium thermoautotrophicum was elucidated by analysing overlapping peptides obtained from partial acid hydrolysates of isolated sacculi. It is suggested that the peptide subunits are attached to glycan strands via one of their glutamyl residues. Another glutamyl residue may crosslink two adjacent peptide subunits to form a dimer. The calculated molar ratios of the amino acids and the percentages of the N-or C-terminal amino acid residues of the supposed dimers are compatible with those actually found in the sacculus polymer.
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  • 9
    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.
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  • 10
    ISSN: 1432-072X
    Keywords: Collagenase ; Alkaline protease ; Temperature control ; Oxygen control ; Regulation ; Vibrio alginolyticus ; Secretion exoproteins ; Cerulenin ; Quinacrine ; Microbial ecology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The production of an extracellular collagenase and an alkaline protease by Vibrio alginolyticus during stationary phase was inhibited by a temperature shift from 30 to 37°C and by a lack of oxygen. The stability of the exoproteases was unaffected by incubation at 37°C and aeration. The optimum growth temperature for the V. alginolyticus strain was 33.5°C Aeration enhanced the rate of growth of exponential phase cells. Temperature and oxygen did not affect the growth of stationary phase cells when the exoproteases were being produced. Macromolecular synthesis in stationary phase cells was not affected by temperature. There was no rapid release of the exoproteases after temperature shift down and chloramphenicol inhibited the production of the enzymes when added at time of temperature shift down from 37 to 30°C. The regulation of exoprotease production by temperature and oxygen was specific and has implications regarding the ecology of V. alginolyticus. Cerulenin, quinacrine and O-phenanthroline inhibited the production of the exoproteases.
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