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  • Escherichia coli  (2)
  • E. coil  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Unsaturated fatty acid requirement inEscherichia coli: Mechanism of palmitate-induced inhibition of growth of strain WN1 (1982)
    Springer
    The journal of membrane biology 65 (1982), S. 31-40 
    Details
    ISSN: 1432-1424
    Keywords: lipids ; membranes ; Escherichia coli ; temperature adaptation ; fatty acids ; phase separations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The minimum requirement for unsaturated fatty acids was investigated inE. coli using a mutant impaired in the synthesis of vaccenic acid. Exogenously supplied palmitic acid was incorporated by this mutant which led to a reduction in the proportion of cellular unsaturated fatty acids. Growth was impaired as the level of saturated fatty acids approached 76% at 37°C and 60% at 30°C. The basis of this growth inhibition was investigated. Most transport systems and enzymes examined remained active in palmitate-grown cells although the specific activities of glutamate uptake and succinic dehydrogenase were depressed 50%. Fluorescent probes of membrane organization indicated that fluidity decreased with palmitate incorportation. Temperature scans with parinaric acid indicated that rigid lipid domains exist in palmitategrown cells at their respective growth temperature. Freeze-fracture electron microscopy confirmed the presence of phase separations (particle-free areas) in palmitate-grown cells held at their growth temperature prior to quenching. The extent of this separation into particle-free and particle-enriched domains was equivalent to that induced by a shift to 0°C in control cells. The incorporation of palmitate increased nucleotide leakage over threefold. The cytoplasmic enzyme β-galactosidase was released into the surrounding medium as the concentration of unsaturated fatty acid approached the minimum for a particular growth temperature. Lysis was observed as a decrease in turbidity when cells which had been grown with palmitate were shifted to a lower growth temperature. From these results we propose that leakage and partial lysis are the major factors contributing to the apparent decrease in growth rate caused by the excessive incorporation of palmitate. Further, we propose that membrane integrity may determine the minimum requirement for unsaturated fatty acids inE. coli rather than a specific effect on membrane transport and/or membrane-bound enzymes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01870466
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Parametric studies of ethanol production form xylose and other sugars by recombinant Escherichia coliFlorida Agricultural Experiment Station Publication Number R-01082. (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 38 (1991), S. 296-303 
    Details
    ISSN: 0006-3592
    Keywords: ethanol ; genetic engineering ; Escherichia coli ; lignocellulose ; xylose ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The conversion of xylose to ethanol by recombinant Escherichia coli has been investigated in pH-controlled batch fermentations. Chemical and environmental parameters were varied to determine tolerance and to define optimal conditions. Relatively high concentrations of ethanol (56 g/L) were produced from xylose with excellent efficiencies. Volumetric productivities of up to 1.4 g ethanol/L h were obtained. Productivities, yields, and final ethanol concentrations achieved from xylose with recombinant E. coli exceeded the reported values with other organisms. In addition to xylose, all other sugar constituents of biomass (glucose, mannose, arabinose, and galactose) were efficiently converted to ethanol by recombinant E. coli. Unusually low inocula equivalent to 0.033 mg of dry cell weight/L were adequate for batch fermentations. The addition of small amounts of calcium, magnesium, and ferrous ions stimulated fermentation. The inhibitory effects of toxic compounds (salts, furfural, and acetate) which are present in hemicellulose hydrolysates were also examined.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260380311
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  • 3
    Electronic Resource
    Electronic Resource
    Fermentation of sweet whey by ethanologenic Escherichia coliFlorida Agricultural Experiment Station Publication Number R-01831. (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 40 (1992), S. 41-45 
    Details
    ISSN: 0006-3592
    Keywords: lactose ; whey ; E. coil ; ethanol ; kluyveromyces fragilis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Whey, an abundant byproduct of the dairy industry, contains large amounts of protein and lactose which could be used for fuel ethanol production. We have investigated a new organism as a candidate for such fermentations: recombinant Escherichia coli containing the genes encoding the ethanol pathway from Zymomonas mobilis. The highest level of ethanol achieved, 68 g/L, was produced after 108 hours in Luria broth containing 140 g lactose/L. Fermentations of lower lactose concentrations were completed more rapidly with approximately 88% of theoretical yields. Reconstituted sweet whey (60 g lactose/L)was fermented more slowly than lactose in Luria broth requiring 144 hours to produce 26 g ethanol/L. Supplementing sweet whey with a trace metal mix and ammonium sulfate reduced the required fermentation time to 72 hours and increased final ethanol concentration (28 g ethanol/L). By adding proteinases during fermentation, the requirement for ammonia was completely eliminated, and the rate of fermentation further improved (30 g ethanol/L after 48 hours). This latter incresed in rate of ethanol production and ethanol yield are presumed to result from incorporation of amino acids released by hydrolysis of whey proteins. The fermentation of sweet whey by ethanologenic E. coil reduced the nonvolatile residue by approximately 70%. This should reduce biological oxygen demand and reduce the cost of waste treatment. Whey supplemented with trace metals and small amounts of proteinase may represent an economically attractive feedstock for the production of ethanol and other useful chemicals.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260400107
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