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  • 1
    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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  • 2
    ISSN: 1432-072X
    Keywords: Photosynthesis ; Regulation ; Thioredoxin ; Cyanobacterium ; Chromatium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Enzymes that are regulated by the ferredoxin/thioredoxin system in chloroplasts — fructose-1,6-bisphosphatase (FBPase), sedoheptulose-1,7-bisphosphatase purified from two different types of photosynthetic prokaryotes (cyanobacteria, purple sulfur bacteria) and tested for a response to thioredoxins. Each of the enzymes from the cyanobacterium Nostoc muscorum, an oxygenic organism known to contain the ferredoxin/thioredoxin system, was activated by thioredoxins that had been reduced either chemically by dithiothreitol or photochemically by reduced ferredoxin and ferredoxin-thioredoxin reductase. Like their chloroplast counterparts, N. muscorum FBPase and SBPase were activated preferentially by reduced thioredoxin f. SBPase was also partially activated by thioredoxin m. PRK, which was present in two regulatory forms in N. muscorum, was activated similarly by thioredoxins f and m. Despite sharing the capacity for regulation by thioredoxins, the cyanobacterial FBPase and SBPase target enzymes differed antigenically from their chloroplast counterparts. The corresponding enzymes from Chromatium vinosum, an anoxygenic photosynthetic purple bacterium found recently to contain the NADP/thioredoxin sytem, differed from both those of cyanobacteria and chloroplasts in showing no response to reduced thioredoxin. Instead, C. vinosum FBPase, SBPase, and PRK activities were regulated by a metabolite effector, 5′-AMP. The evidence is in accord with the conclusion that thioredoxins function in regulating the reductive pentose phosphate cycle in oxygenic prokaryotes (cyanobacteria) that contain the ferredoxin/thioredoxin system, but not in anoxygenic prokaryotes (photosynthetic purple bacteria) that contain the NADP/thioredoxin system. In organisms of the latter type, enzyme effectors seem to play a dominant role in regulating photosynthetic carbon dioxide assimilation.
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  • 3
    ISSN: 1432-072X
    Keywords: Rhodospirillum rubrum ; Rhodospirillum tenue ; Adaptation to chemotrophy ; Respiration ; Cytochrome c-oxidase ; Regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In spite of previous reports, the activities of respiratory oxygen uptake by whole cells are higher with chemotrophically than with phototrophically grown cells of Rhodospirillum rubrum and Rhodospirillum tenue. The same applies to NADH dependent respiratory reactions as determined with isolated crede membrane preparations. This is largely, but not only, due to an outstandingly high increase in activity of cytochrome c-oxidase measurable upon adaptation of phototrophically grown cells to chemotrophic conditions. In R. rubrum the dependency of the total respiratory chain on the activities of different sections of this chain becomes confused by the presence of differently composed membranes (i.e. cytoplasmic and intracytoplasmic membranes) which under the experimental conditions become functionally differentiated to different extents. But in R. tenue, which does not produce intracytoplasmic membranes, respiration at low activities parallels clearly cytochrome c oxidase activities while high respiratory activities parallel the activities of NADH dehydrogenase. The data are interpreted to indicate that, in cells of facultative phototrophic bacteria, the formation of the respiratory chain, up to certain stages, depends on the formation of the terminal oxidase. At least in R. tenue this is comparable to the role of bacteriochlorophyll in the formation of the photosynthetic apparatus.
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  • 4
    ISSN: 1432-072X
    Keywords: Escherichia coli ; Ether permeabilized cells ; Murein biosynthesis ; Inhibition ; Regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract ETB, ether treated bacteria, from E. coli and other Gram-negative strains, contain in a cell-free system all enzymes necessary for murein biosynthesis. Starting with a variety of combinations of peptidoglycan precursors, high yields of sodium dodecylsulfate (SDS, 4%) insoluble murein or murein like material were synthesized. The amount of newly synthesized SDS insoluble material (NSM) was dependent upon the growing phase at which cells had been harvested for preparation of ETB. This data may provide some insight into the regulation of peptidoglycan biosynthesis. Starting from early peptidoglycan precursors, the cell-free synthesis of NSM was inhibited by specific inhibitors of murein synthesis, such as D-cycloserine, D-fluoroalanine, 2-amino-ethylphosphonate, analogues of D-alanyl-D-alanine and β-lactam antibiotics at appropriate concentrations. Some D-alanyl-D-alanine analogues and 4-chlorodiaminopimelic acid were incorporated into NSM in place of their corresponding natural substrates.
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  • 5
    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.
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  • 6
    ISSN: 1432-072X
    Keywords: Rhizobium japonicum ; Formate utilisation ; Formate dehydrogenase ; Ribulose bisphosphate carboxylase ; Hydrogenase ; Hydrogen uptake ; Regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Rhizobium japonicum CJ1 was capable of growing using formate as the sole source of carbon and energy. During aerobic growth on formate a cytoplasmic NAD+-dependent formate dehydrogenase and ribulose bisphosphate carboxylase activity was demonstrated in cell-free extracts, but hydrogenase enzyme activity could not be detected. Under microaerobic growth conditions either formate or hydrogen metabolism could separately or together support ribulose bisphosphate carboxylase-dependent CO2 fixation. A number of R. japonicum strains defective in hydrogen uptake activity were shown to metabolise formate and induce ribulose bisphosphate carboxylase activity. The induction and regulation of ribulose bisphosphate carboxylase is discussed.
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  • 7
    ISSN: 1432-072X
    Keywords: Ions ; Concentration ; Regulation ; Cytoplasm ; Vacuole ; Yeast ; Saccharomyces carlsbergensis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Intracellular distributions of K+, Mg2+ and orthophosphate under various conditions of cultivation or incubation of the yeast Saccharomyces carlsbergensis were studied by differential extraction of ion pools. The decisive role of vacuolar compartmentation of ions in regulation of K+, Mg2+ and orthophosphate levels in the yeast cytoplasm was shown. The content of intracellular K+ and Mg2+ in yeast increased or decreased primarily depending on the increase or decrease in the vacuolar ion pool. The levels of K+ and Mg2+ in the cytoplasm were practically unchanged. Vacuoles were involved in regulation of Mn2+ concentration in the cytoplasm of the yeast S. carlsbergensis accumulating this ion in the presence of glucose. Alongside the vacuolar compartmentation, the chemical compartmentation, i. e. formation of bound Mg2+, Mn2+ and K+ was, evidently, also involved in the control of ion levels in the cytoplasm. The orthophosphate level in the yeast cytoplasm was regulated by its accumulation in vacuoles and biosynthesis of inorganic polyphosphates in these organelles. The biosynthesis of low-molecular weight polyphosphates occurred parallel to the accumulation of Mg2+ or Mn2+ in vacuoles, thus confirming the availability of the other mechanism for the transport of these ions through the tonoplast differing from the transport mechanism through the plasmalemma.
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  • 8
    ISSN: 1432-072X
    Keywords: Bacillus caldotenax ; Main metabolic Pathways ; Enzyme activities at different growth rates ; Isocitrate lyase ; Regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Bacillus caldotenax was cultivated in chemostat experiments at 65°C with a chemically defined minimal medium. Glycolysis, tricarboxylic acid cycle, pentose phosphate pathway and the respiratory chain were active as demonstrated by measuring the corresponding enzymes. No enzyme activity of the Entner-Doudoroff pathway could be detected. The specific activities of the citrate cycle enzymes were up to 10 times higher as compared to the enzymes of glycolysis. At dilution rates between 0.3 and 2.2 h-1 none of the main metabolic pathways was regulated. In contrast the isocitrate lyase was regulated (drop of activity with increasing growth rates). As a result of a batch culture with glucose and acetate as carbon sources a regulation model was proposed: glucose, or a metabolite of glucose, represses the isocitrate lyase; in the absence of glucose acetate acts as an inducer.
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  • 9
    ISSN: 1432-072X
    Keywords: Cephalosporium acremonium ; Cephalosporin ; Regulation ; Phosphate ; Glucose ; Fed-batch ; Chemostat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The regulation of cephalosporin synthesis in Cephalosporium acremonium was studied in a simple chemically-defined medium with glucose as the carbon source. Antibiotic synthesis depended on the phosphate content of the medium. At phosphate concentrations above 2.75 mM maximum antibiotic titres were not reached while glucose uptake and growth rates were increased. Phosphate exerted its effect indirectly by regulating the rate of glucose consumption. The negative effect of high phosphate concentrations could be overcome completely by controlling the sugar supply in fed-batch and chemostat experiments. High actual concentrations of phosphate or of glucose alone had no direct negative effect on antibiotic synthesis.
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  • 10
    ISSN: 1432-072X
    Keywords: Ammonium transport ; Regulation ; Rhodospirillum rubrum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An ammonium transport system in the phototrophic N2-fixing bacteriumRhodospirillum rubrum was characterized by using the uptake of14C-methylamine as a probe. Uptake showed saturation kinetics with an apparentK m =110 μM. It was competitively inhibited by ammonium (K i =7 μM). Uptake exhibited a narrow pH maximum around pH 7.0. Up to 200-fold gradients across the membrane were formed within 40–60 min. Gradient formation was inhibited by carbon starvation, azide or cyanide. Pre-accumulated methylamine was released by ammonium pulses to more than 80%, indicating only minor metabolization. The synthesis of the transport system was repressed by ammonium in high concentrations.
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