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  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Archives of environmental contamination and toxicology 15 (1986), S. 669-676 
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract Studies were made with pentachlorophenol (PCP) to determine the effects of temperature, air flow, humidity, carrier solvents, and wood coating systems on the vaporization properties of PCP. Temperature had the greatest effect on PCP vaporization from treated wood. Methylene chloride was associated with the highest air concentrations of PCP. The cosolvent WC-144 was most effective in reducing PCP vaporization, and a bituminous coating and an epoxy paint were the most effective coatings for reducing PCP vaporization from treated wood.
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 136 (1935), S. 548-549 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Now that measurements of upper-atmospheric ionisation can be made, using methods of radio exploration, it is of interest to see whether abnormal values of ionisation density are associated with periods of magnetic activity. We have conducted such an inquiry using the measurements of ionisation ...
    Type of Medium: Electronic Resource
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  • 13
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 24 (1968), S. 1233-1236 
    ISSN: 1600-5740
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
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  • 14
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Gene libraries (“zoolibraries”) were constructed in Escherichia coli using DNA isolated from the mixed liquor of thermophilic, anaerobic digesters, which were in continuous operation with lignocellulosic feedstocks for over 10 years. Clones expressing cellulase and xylosidase were readily recovered from these libraries. Four clones that hydrolyzed carboxymethylcellulose and methylumbelliferyl-β-d-cellobiopyranoside were characterized. All four cellulases exhibited temperature optima (60–65° C) and pH optima (pH 6–7) in accordance with conditions of the enrichment. The DNA sequence of the insert in one clone (plasmid pFGH1) was determined. This plasmid encoded an endoglucanase (celA) and part of a putative β-glucosidase (celB), both of which were distinctly different from all previously reported homologues. CelA protein shared limited homology with members of the A3 subfamily of cellulases, being similar to endoglucanase C from Clostridium thermocellum (40% identity). The N-terminal part of CelB protein was most similar to β-glucosidase from Pseudomonas fluorescens subsp. cellulosa (28% homology). The use of zoolibraries constructed from natural or laboratory enrichment cultures offers the potential to discover many new enzymes for biotechnological applications.
    Type of Medium: Electronic Resource
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  • 15
    Electronic Resource
    Electronic Resource
    Springer
    Applied microbiology and biotechnology 43 (1995), S. 70-75 
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  Hemicellulose hydrolysates of agricultural residues often contain mixtures of hexose and pentose sugars. Ethanologenic Escherichia coli that have been previously investigated preferentially ferment hexose sugars. In some cases, xylose fermentation was slow or incomplete. The purpose of this study was to develop improved ethanologenic E. coli strains for the fermentation of pentoses in sugar mixtures. Using fosfomycin as a selective agent, glucose-negative mutants of E. coli KO11 (containing chromosomally integrated genes encoding the ethanol pathway from Zymomonas mobilis) were isolated that were unable to ferment sugars transported by the phosphoenolpyruvate-dependent phosphotransferase system. These strains (SL31 and SL142) retained the ability to ferment sugars with independent transport systems such as arabinose and xylose and were used to ferment pentose sugars to ethanol selectively in the presence of high concentrations of glucose. Additional fosfomycin-resistant mutants were isolated that were superior to strain KO11 for ethanol production from hexose and pentose sugars. These hyperproductive strains (SL28 and SL40) retained the ability to metabolize all sugars tested, completed fermentations more rapidly, and achieved higher ethanol yields than the parent. Both SL28 and SL40 produced 60 g l-1 ethanol from 120 g l-1 xylose in 60 h, 20% more ethanol than KO11 under identical conditions. Further studies illustrated the feasibility of sequential fermentation. A mixture of hexose and pentose sugars was fermented with near theoretical yield by SL40 in the first step followed by a second fermentation in which yeast and glucose were added. Such a two-step approach can combine the attributes of ethanologenic E. coli for pentoses with the high ethanol tolerance of conventional yeasts in a single vessel.
    Type of Medium: Electronic Resource
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  • 16
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  Gene libraries (“zoolibraries”) were constructed in Escherichia coli using DNA isolated from the mixed liquor of thermophilic, anaerobic digesters, which were in continuous operation with lignocellulosic feedstocks for over 10 years. Clones expressing cellulase and xylosidase were readily recovered from these libraries. Four clones that hydrolyzed carboxymethylcellulose and methylumbelliferyl-β-D-cellobiopyranoside were characterized. All four cellulases exhibited temperature optima (60–65 °C) and pH optima (pH 6–7) in accordance with conditions of the enrichment. The DNA sequence of the insert in one clone (plasmid pFGH1) was determined. This plasmid encoded an endoglucanase (celA) and part of a putative β-glucosidase (celB), both of which were distinctly different from all previously reported homologues. CelA protein shared limited homology with members of the A3 subfamily of cellulases, being similar to endoglucanase C from Clostridium thermocellum (40% identity). The N-terminal part of CelB protein was most similar to β-glucosidase from Pseudomonas fluorescens subsp. cellulosa (28% homology). The use of zoolibraries constructed from natural or laboratory enrichment cultures offers the potential to discover many new enzymes for biotechnological applications.
    Type of Medium: Electronic Resource
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  • 17
    Electronic Resource
    Electronic Resource
    Springer
    Applied microbiology and biotechnology 43 (1995), S. 70-75 
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Hemicellulose hydrolysates of agricultural residues often contain mixtures of hexose and pentose sugars. Ethanologenic Escherichia coli that have been previously investigated preferentially ferment hexose sugars. In some cases, xylose fermentation was slow or incomplete. The purpose of this study was to develop improved ethanologenic E. coli strains for the fermentation of pentoses in sugar mixtures. Using fosfomycin as a selective agent, glucose-negative mutants of E. coli KO11 (containing chromosomally integrated genes encoding the ethanol pathway from Zymomonas mobilis) were isolated that were unable to ferment sugars transported by the phosphoenolpyruvate-dependent phosphotransferase system. These strains (SL31 and SL142) retained the ability to ferment sugars with independent transport systems such as arabinose and xylose and were used to ferment pentose sugars to ethanol selectively in the presence of high concentrations of glucose. Additional fosfomycin-resistant mutants were isolated that were superior to strain KO11 for ethanol production from hexose and pentose sugars. These hyperproductive strains (SL28 and SL40) retained the ability to metabolize all sugars tested, completed fermentations more rapidly, and achieved higher ethanol yields than the parent. Both SL28 and SL40 produced 60 gl−1 ethanol from 120 gl−1 xylose in 60 h, 20% more ethanol than KO11 under identical conditions. Further studies illustrated the feasibility of sequential fermentation. A mixture of hexose and pentose sugars was fermented with near theoretical yield by SL40 in the first step followed by a second fermentation in which yeast and glucose were added. Such a two-step approach can combine the attributes of ethanologenic E. coli for pentoses with the high ethanol tolerance of conventional yeasts in a single vessel.
    Type of Medium: Electronic Resource
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  • 18
    Electronic Resource
    Electronic Resource
    Springer
    Journal of industrial microbiology and biotechnology 16 (1996), S. 374-376 
    ISSN: 1476-5535
    Keywords: soy ; hydrolysate ; nutrient ; fermentation ; ethanol ; amino acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract An optimized soy-based medium was developed for ethanol production byEscherichia coli KO11. The medium consists of mineral salts, vitamins, crude enzymatic hydrolysate of soy and fermentable sugar. Ethanol produced after 24 h was used as an endpoint in bioassays to optimize hydrolysate preparation. Although longer fermentation times were required with soy medium than with LB medium, similar final ethanol concentrations were achieved (44–45 g ethanol L−1 from 100 g glucose L−1). The cost of materials for soy medium (excluding sugar) was estimated to be $0.003 L−1 broth, $0.006 L−1 ethanol.
    Type of Medium: Electronic Resource
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  • 19
    Electronic Resource
    Electronic Resource
    Springer
    Journal of industrial microbiology and biotechnology 20 (1998), S. 132-138 
    ISSN: 1476-5535
    Keywords: Keywords: ethanol; ethanol tolerance; fermentation; xylose; biomass; lignocellulose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Genetically engineered Escherichia coli KO11 is capable of efficiently producing ethanol from all sugar constituents of lignocellulose but lacks the high ethanol tolerance of yeasts currently used for commercial starch-based ethanol processes. Using an enrichment method which selects alternatively for ethanol tolerance during growth in broth and for ethanol production on solid medium, mutants of KO11 with increased ethanol tolerance were isolated which can produce more than 60 g ethanol L−1 from xylose in 72 h. Ethanol concentrations and yields achieved by the LY01 mutant with xylose exceed those reported for recombinant strains of Saccharomyces and Zymomonas mobilis, both of which have a high native ethanol tolerance.
    Type of Medium: Electronic Resource
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  • 20
    Electronic Resource
    Electronic Resource
    Springer
    Journal of industrial microbiology and biotechnology 20 (1998), S. 281-286 
    ISSN: 1476-5535
    Keywords: Keywords: lignocellulose; biomass; fermentation; ethanol; E. coli KO11; xylose; process errors; process upsets
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Escherichia coli KO11 was previously constructed for the production of ethanol from both hexose and pentose sugars in hemicellulose hydrolysates by inserting the Zymomonas mobilis genes encoding pyruvate decarboxylase (pdc) and alcohol dehydrogenase (adhB). This biocatalyst appears relatively resistant to potential process errors during fermentation. Antibiotics were not required to maintain the maximum catabolic activity of KO11 even after deliberate contamination with up to 10% soil. Fermentations exposed to extremes of temperature (2 h at 5°C or 50°C) or pH (2 h at pH 3 or pH 10) recovered after re-adjustment to optimal fermentation conditions (35°C, pH6) although longer times were required for completion in most cases. Ethanol yields were not altered by exposure to extremes in temperature but were reduced by exposure to extremes in pH. Re-inoculation with 5% (by volume) from control fermentors reduced this delay after exposure to pH extremes.
    Type of Medium: Electronic Resource
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