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  • 1
    Electronic Resource
    Electronic Resource
    Die beim Abbau vonl-Äpfelsäure durch Milchsäurebakterien entstehenden Isomeren der Milchsäure (1970)
    Springer
    Naturwissenschaften 57 (1970), S. 672-672 
    Details
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00598799
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  • 2
    Electronic Resource
    Electronic Resource
    Identification and characterisation of the extracellular sucrases of Zymomonas mobilis UQM 2716 (ATCC 39676) (1994)
    Springer
    Applied microbiology and biotechnology 41 (1994), S. 302-308 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract An investigation was conducted to isolate, and characterise the extracellular sucrases of Zymomonas mobilis UQM 2716. Levansucrase (EC 2.4.1.10) was the only extracellular sucrase produced by this organism. This enzyme was responsible for sucrose hydrolysis, levan formation, and oligosaccharide production. It had a molecular mass of 98 kDa, a Michaelis constant (K m) of 64 mm, and a pH optimum of 5.5. It was inhibited by glucose, but not by fructose, ethanol, sorbitol, NaCl, TRIS or ethylenediaminetetraacetic acid (EDTA). The formation of levan was the principal reaction catalysed by this enzyme at low temperatures. However, levan formation was thermolabile, being irreversibly lost when levansucrase was heated to 35°C. S This did not effect sucrose hydrolysis or oligosaccharide formation, which were optimal at 45°C. Sucrose concentration greatly influenced the type of acceptor molecule used in the transfructosylation reactions catalysed by levansucrase. At low sucrose concentration, the predominant reaction catalysed was the hydrolysis of sucrose to free glucose and fructose. At high sucrose concentrations, oligosaccharide production was the major reaction catalysed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00221223
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  • 3
    Electronic Resource
    Electronic Resource
    Comparative study of d-xylose conversion to ethanol by immobilized growing or non-growing cells of the yeast Pachysolen tannophilus (1988)
    Springer
    Applied microbiology and biotechnology 27 (1988), S. 325-332 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The direct conversion of d-xylose to ethanol was investigated using immobilized growing and non-growing cells of the yeast Pachysolen tannophilus. Both preparations produced ethanol from d-xylose, however the d-xylose conversion to ethanol was much better with immobilized growing cells. Ethanol concentration up to 22.9 g/l and ethanol yield of 0.351 g/g of d-xylose were obtained in batch fermentation by immobilized growing cells whereas only 17.0 g/l and 0.308 g/g of d-xylose were obtained by immobilized non-growing cells. With continuous systems, immobilized growing cells were necessary for the long-term operation, since a steady state ethanol concentration of 17.7 g/l was maintained for only one week by immobilized non-growing cell reactor. With simultaneous control of aeration rate and concentrations of nitrogen sources in feed medium, immobilized growing cells of P. tannophilus showed excellent performance. At a residence time of 25 h, the immobilized cell reactor produced 26.9 g/l of ethanol from 65 g/l of d-xylose in feed medium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00251762
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  • 4
    Electronic Resource
    Electronic Resource
    Identification and characterisation of the extracellular sucrases of Zymomonas mobilis UQM 2716 (ATCC 39676) (1994)
    Springer
    Applied microbiology and biotechnology 41 (1994), S. 302-308 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  An investigation was conducted to isolate, and characterise the extracellular sucrases of Zymomonas mobilis UQM 2716. Levansucrase (EC 2.4.1.10) was the only extracellular sucrase produced by this organism. This enzyme was responsible for sucrose hydrolysis, levan formation, and oligosaccharide production. It had a molecular mass of 98 kDa, a Michaelis constant (K m) of 64 mM, and a pH optimum of 5.5. It was inhibited by glucose, but not by fructose, ethanol, sorbitol, NaCl, TRIS or ethylenediaminetetraacetic acid (EDTA). The formation of levan was the principal reaction catalysed by this enzyme at low temperatures. However, levan formation was thermolabile, being irreversibly lost when levansucrase was heated to 35°C. This did not effect sucrose hydrolysis or oligosaccharide formation, which were optimal at 45°C. Sucrose concentration greatly influenced the type of acceptor molecule used in the transfructosylation reactions catalysed by levansucrase. At low sucrose concentration, the predominant reaction catalysed was the hydrolysis of sucrose to free glucose and fructose. At high sucrose concentrations, oligosaccharide production was the major reaction catalysed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002530050148
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  • 5
    Electronic Resource
    Electronic Resource
    6-Phosphogluconate dehydrogenase in cell free extracts of Escherichia coli K-12 (1968)
    Springer
    Archives of microbiology 63 (1968), S. 214-223 
    Details
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Investigations into the properties of 6-PG dehydrogenase in cell free extracts of Escherichia coli revealed a pH optimum at pH 9.5 with a sharp decline on both sides of the optimum. The addition of 1.0×10-2 m MgCl2 produced maximal activity, whereas higher concentrations caused inhibition. The K m values were 2.5×10-4 m for 6-phosphogluconate and 2.5×10-5 m for NADP+ as substrate. The enzyme was extremely stable for at least 5 hours if stored at 4°C in Tris−NaCl−MgCl2 buffer at pH 7.5. 6-PG dehydrogenase activity was shown to be proportional to cell free extract concentration over the range 0–0.3 mg protein. An assay method based on the new optimal conditions has been established and has been shown to be 33% more sensitive than a number of commonly used methods.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00412837
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  • 6
    Electronic Resource
    Electronic Resource
    Glucose-6-phosphate dehydrogenase in cell free extracts of Zymomonas mobilis (1968)
    Springer
    Archives of microbiology 63 (1968), S. 197-213 
    Details
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Glucose-6-phosphate dehydrogenase activity in cell free extracts o Zymomonas mobilis showed marked differences when compared with the corresponding enzyme of Escherichia coli. It exhibited 3 times higher activity and the reaction rate over 10 min gave linearity only up to a cell free protein concentration of 0.15 mg protein. This different behaviour was not a function of environmental growth conditions of the culture nor of the nine different assay methods employed. A constant relationship existed between the specific G-6-P dehydrogenase protein and the total protein concentration in the cell free extract. The enzyme was stable for at least 5 h at 4°C in Tris-NaCl-MgCl2-buffer. An investigation of the properties of G-6-P dehydrogenase from Z. mobilis revealed a pH optimum of 8.7 with a rapid decline towards the acidic and a small decrease towards the alkaline side. The K m values were 5×10-4 m for glucose-6-phosphate and 3.6×10-5 m NADP+. The addition of 1×10-2 m MgCl2 produced optimal activity but higher concentrations inhibited the enzyme reaction. These results were discussed with those from other sources and found to be unique for Zymomonas mobilis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00412836
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  • 7
    Electronic Resource
    Electronic Resource
    Preparation of extracts of culture liquids for gas-chromatographic determination of non-acidic fermentation products (1966)
    Springer
    Antonie van Leeuwenhoek 32 (1966), S. 373-380 
    Details
    ISSN: 1572-9699
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A simplified extraction method of high efficiency has been worked out to permit the determination of small amounts of alcohols present in fermentation solutions. Methods of extracting are described for large and small amounts of culture media. The proposed method has been successfully applied to known amounts of alcohol in bacterial fermentation solutions. Clostridium acetobutylicum andZymomonas mobilis were used for this investigation. The method is described in details with theClostridium culture.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02097486
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  • 8
    Electronic Resource
    Electronic Resource
    Preparation of extracts of culture liquids for gas-chromatographic determination of acidic fermentation products (1969)
    Springer
    Antonie van Leeuwenhoek 35 (1969), S. 467-478 
    Details
    ISSN: 1572-9699
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An extraction method coupled with gas-chromatographic analysis has been devised for the determination of small amounts of C1-C7 branched and straight-chain saturated fatty acids as well as 18 mono-, di- and tricarboxylic acids and related compounds, the latter being analyzed either as their methylesters or as their trimethylsilyl-derivatives. Methods for extracting non-volatile acids or both volatile and non-volatile acids are described for large and small volumes of culture media. The proposed methods have been successfully applied to the determination of non-acidic fermentation products, known amounts of alcohols, and to volatile and non-volatile acids in bacterial fermentation solutions, namely a batch culture ofLactobacillus casei subsp.rhamnosus ATCC 7469. A carbon balance sheet of this organism's metabolic behaviour throughout growth is proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02219165
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  • 9
    Electronic Resource
    Electronic Resource
    Comparative studies of fructose 1,6-diphosphate aldolase fromEscherichia coli 518 andLactobacillus casei var.rhamnosus ATCC 7469 (1971)
    Springer
    Antonie van Leeuwenhoek 37 (1971), S. 21-31 
    Details
    ISSN: 1572-9699
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A comparative study has been carried out with FDP aldolases fromEscherichia coli 518 andLactobacillus casei ATCC 7469, which had been purified 17.6- and 65-fold, respectively. The aldolase ofL.casei was stable only in the presence of mercaptoethanol, whereas that ofE.coli was strongly inhibited at low (1.0×10−4 m) and activated at high concentrations (2.0×10−1 m) of the same compound.p-Chloromercuric benzoic acid inhibited both aldolases, with 40% inhibition at 2×10−5 m withE.coli aldolase against at 2×10−4 m withL.casei aldolase. Significant differences were also observed in pH optima and Km values.E.coli aldolase exhibited a maximal activity at pH 9.0 and gave a Km value of 1.76×10−3 m FDP with strong substrate inhibition above 7×10−3 m, against pH 6.8–7.0 and a Km of 7.04×10−3 m FDP forL.casei aldolase. Strong resistance ofL.casei aldolase against inhibition by EDTA, Ca2+ and Mn2+ was observed compared with complete inhibition at concentrations of 20mm, 40mm and 20mm, respectively, withE. coli aldolase. Polyacrylamide gel electrophoresis did not reveal any differences between the two enzyme preparations. The differences of the properties of FDP aldolases from different bacterial genera are discussed in relation to other Class II aldolases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02218464
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  • 10
    Electronic Resource
    Electronic Resource
    The influence of dissolved oxygen concentration on phosphofructokinase and the glucose metabolism ofEscherichia coli K-12 (1971)
    Springer
    Antonie van Leeuwenhoek 37 (1971), S. 497-506 
    Details
    ISSN: 1572-9699
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The glucose metabolism and the response of phosphofructokinase activity to oxygen were investigated using glucose-limited chemostat cultures ofE. coli K-12. With a dilution rate of 0.2 hr−1 and a glucose input concentration of 0.83 g/litre, 10 steady states were obtained ranging from 320 to 0 mm HgO2. Dissolved oxygen reached zero level at a pO2 of 25.8 mm Hg. The specific phosphofructokinase activity was constant above 28 mm Hg O2 and increased linearly at lower pO2 levels until it reached highest activity at 0 mm Hg O2. Cell dry weight also started to decrease linearly from 28 to 5.9 mm Hg O2, and fell sharply thereafter. Acid production rate did not start before pO2 reached 25.6 mm Hg, increased progressively with an additional sharp increase below 5.9 mm Hg O2. The main endproducts formed were acetic acid and ethanol with lactic acid appearing below 5.9 mm Hg O2. The results suggest an effect of oxygen on phosphofructokinase synthesis rather than an ATP inhibition of the enzyme.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02218520
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