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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.
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  • 2
    ISSN: 1432-072X
    Keywords: Marine luminous bacteria ; Symbiosis ; Vibrio fischeri ; Cleidopus gloriamaris ; Taxonomy ; Ecology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Luminous bacteria isolated from the light organs of the Australian Pinecone fish Cleidopus gloriamaris have been studied. The isolates were from fish from four different geographical estuarine systems on the east coast of Australia. All isolates were found to be strains of Vibrio fischeri, a species not hitherto demonstrated conclusively as forming a symbiotic association. Some ecological considerations are discussed.
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  • 3
    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.
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  • 4
    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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  • 5
    ISSN: 1432-072X
    Keywords: Kluyveromyces marxianus ; Hybridization ; Interfertility ; Conspecificity ; Taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Hybridization studies between strains of Kluyveromyces marxianus and the remaining species of the genus involving the use of auxotrophic mutants, are reported. K. marxianus was found to be interfertile with K. bulgaricus, K. cicerisporus, K. dobzhanskii, K. drosophilarum, K. fragilis, K. lactis, K. phaseolosporus, K. vanudenii and K. wikenii. Accepting interfertility as criterion for conspecificity, these nine syngamous taxa are relegated to the status of biotypes or physiologic races of a single species K. marxianus.
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  • 6
    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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  • 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: 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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  • 9
    ISSN: 1432-072X
    Keywords: Phototrophic bacteria ; Chlorobium ; Chloroflexus ; Lipids ; Taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The lipid compositions of Chlorobium limicola (4 strains) and Chloroflexus aurantiacus (2 strains) have been compared. Both species contained straight-chain, saturated and monosaturated fatty acids as their main fatty acid constituents but the patterns were distinctly different. Chlorobium contained acids of chain-length essentally in the range C12−C18 with n-tetradecanoate, hexadecenoate and n-hexadecanoate predominating. Chloroflexus was characterized by the presence of significant amounts of C17 and C18−C20 fatty acids not detected in Chlorobium. The latter, on the other hand, contained hydroxylated and cyclopropane-substituted acids not detected in Chloroflexus. Simple wax esters (C28−C38) were found solely in Chloroflexus and accounted for 2.5–3.0% of the cell dry weight. Their fatty acid constituents ranged from C12−C19 (both saturated and monounsaturated isomers) whereas the alcohols were generally saturated and of chain-length C16−C19. Waxes in the range C34−C36 accounted for more than 60% of the total. The polar lipid patterns of the two genera also showed marked differences. All strains contained phosphatidyl-glycerol, monogalactosyl diglyceride and sulfoquinovosyldiglyceride. Chlorobium contained in addition cardiolipin, phosphatidylethanolamine, the unidentified “glycolipid II” and several other unidentified glycolipids, whereas phosphatidyl inositol and a diglycosyl diglyceride were specific for Chloroflexus. The latter lipid contained equimolar amounts of glucose and galactose. Phenol-water extraction yielded material comprising 14% of the dry cell weight for Chlorobium but only 2.5% for Chloroflexus. The Chlorobium material contained two 3-hydroxy fatty acids and several uncommon sugars (not identified). The analytical results were inconclusive regarding occurrence of 2-keto-3-deoxyoctonate. No typical lipopoly-saccharide constituents were found in Chloroflexus.
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  • 10
    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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