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  • Escherichia coli  (2)
  • cellulase  (2)
  • 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
    Production of recombinant bacterial endoglucanase as a co-product with ethanol during fermentation using derivatives of Escherichia coli KO11 (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 55 (1997), S. 547-555 
    Details
    ISSN: 0006-3592
    Keywords: ethanol ; cellulose ; hemicellulose ; endoglucanase ; cellulase ; lignocellulose ; biomass ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This study demonstrates a new approach to reduce the amount of fungal cellulase required for the conversion of cellulose into ethanol. Escherichia coli KO11, a biocatalyst developed for the fermentation of hemicellulose syrups, was used to produce recombinant endoglucanase as a co-product with ethanol. Seven different bacterial genes were expressed from plasmids in KO11. All produced cell-associated endoglucanase activity. KO11(pLOI1620) containing Erwinia chrysanthemi celZ (EGZ) produced the highest activity, 3,200 IU endoglucanase/L fermentation broth (assayed at pH 5.2 and 35°C). Recombinant EGZ was solubilized from harvested cells by treatment with dilute sodium dodecyl sulfate (12.5 mg/ml, 10 min, 50°C) and tested in fermentation experiments with commercial fungal cellulase (5 filter paper units/g cellulose) and purified cellulose (100 g/L). Using Klebsiella oxytoca P2 as the biocatalyst, fermentations supplemented with EGZ as a detergent-lysate of KO11(pLOI1620) produced 14%-24% more ethanol than control fermentations supplemented with a detergent-lysate of KO11(pUC18). These results demonstrate that recombinant bacterial endoglucanase can function with fungal cellulase to increase ethanol yield during the simultaneous saccharification and fermentation of cellulose. © 1997 Wiley & Sons, Inc. Biotechnol Bioeng 55: 547-555, 1997.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 3
    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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  • 4
    Electronic Resource
    Electronic Resource
    Saccharification and fermentation of Sugar Cane bagasse by Klebsiella oxytoca P2 containing chromosomally integrated genes encoding the Zymomonas mobilis ethanol pathway (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 240-247 
    Details
    ISSN: 0006-3592
    Keywords: lignocellulose ; ethanol ; Klebisella oxytoca ; fermentation ; cellulase ; cellulose ; cellobiose ; biomass ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Pretreatment of sugar cane bagasse is essential for a simultaneous saccharification and fermentation (SSF) process which uses recombinant Klebsiella oxytoca strain P2 and Genencor Spezyme CE. Strain P2 has been genetically engineered to express Zymomonas mobilis genes encoding the ethanol pathway and retains the native ability to transport and metabolize cellobiose (minimizing the need for extracellular cellobiase). In SSF studies with this organism, both the rate of ethanol production and ethanol yield were limited by saccharification at 10 and 20 filter papaer units (FPU) g-1 acid-treated bagasse. Dilute slurries of biomass were converted to ethanol more efficiently (over 72% of theoretical yield) in simple batch fermentations than slurries containing high solids albeit with the production of lower levels of ethanol. With high solids (i.e., 160 g acid-treated bagasse L-1), a combination of 20 FPU cellulase g-1 bagasse, preincubation under saccharification conditions, and additional grinding (to reduce particle size) were required to produce ca. 40 g ethanol L-1. Alternatively, almost 40 g ethanol L-1 was produced with 10 FPU cellulase g-1 bagasse by incorporating a second saccharification step (no further enzyme addition) followed by a second inoculation and short fermentation. In this way, a theoretical ethanol yield of over 70% was achieved with the production of 20 g ethanol 800 FPU-1 of commercial cellulase. © 1994 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260440213
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    Paper (German National Licenses)
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