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  • 1
    Electronic Resource
    Electronic Resource
    Bacteria tolerant to organic solvents (1998)
    Springer
    Extremophiles 2 (1998), S. 229-238 
    Details
    ISSN: 1433-4909
    Keywords: Key words Solvent-tolerant bacteria ; Adaptation ; Resistance ; Toxicity ; Log P ; Stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The toxic effects that organic solvents have on whole cells is an important drawback in the application of these solvents in environmental biotechnology and in the production of fine chemicals by whole-cell biotransformations. Hydrophobic organic solvents, such as toluene, are toxic for living organisms because they accumulate in and disrupt cell membranes. The toxicity of a compound correlates with the logarithm of its partition coefficient with octanol and water (log P ow). Substances with a log P ow value between 1 and 5 are, in general, toxic for whole cells. However, in recent years different bacterial strains have been isolated and characterized that can adapt to the presence of organic solvents. These strains grow in the presence of a second phase of solvents previously believed to be lethal. Different mechanisms contributing to the solvent tolerance of these strains have been found. Alterations in the composition of the cytoplasmic and outer membrane have been described. These adaptations suppress the effects of the solvents on the membrane stability or limit the rate of diffusion into the membrane. Furthermore, changes in the rate of the biosynthesis of the phospholipids were reported to accelerate repair processes. In addition to these adaptation mechanisms compensating the toxic effect of the organic solvents, mechanisms do exist that actively decrease the amount of the toxic solvent in the cells. An efflux system actively decreasing the amount of solvents in the cell has been described recently. We review here the current knowledge about exceptional strains that can grow in the presence of toxic solvents and the mechanisms responsible for their survival.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007920050065
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  • 2
    Electronic Resource
    Electronic Resource
    Carnitine: a novel compatible solute in Lactobacillus plantarum (1994)
    Springer
    Archives of microbiology 162 (1994), S. 243-248 
    Details
    ISSN: 1432-072X
    Keywords: Key words     Lactobacillus plantarum ; Compatible ; solute ; Osmotic stress ; Carnitine ; Betaine ; Acetylcholine ; Succinylcholine ; γ-Butyrobetaine ; Quaternary ammonium compound
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract      The aim of this study was to unravel the identity of compatible solutes accumulated by Lactobacillus plantarum subjected to osmotic stress. Betaine was accumulated simultaneously with a novel compatible solute identified as carnitine, both present in the complex medium applied in this study. Beef extract provided the main source of carnitine in the medium. Both carnitine and betaine were accumulated to maximum concentrations of 248 and 231 μmol.g dry weight–1, respectively. A defined medium was devised devoid of carnitine. Addition of 0.5 mM carnitine to this medium increased the growth rate from 0.1 h–1 to 0.2 h–1 in media with 0.4 M sodium chloride. Also, carnitine made the organism more tolerant to sodium chloride. Growth occurred even when the sodium chloride concentration was raised from 0.5 M to 1.0 M. Quaternary compo unds resembling the structure of carnitine and betaine enhanced the growth yield as well. γ-Butyrobetaine and succinylcholine restored the growth yield up to respectively 91 and 96% compared to non-stressed cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00301845
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  • 3
    Electronic Resource
    Electronic Resource
    Membrane bioreactor with a porous hydrophobic membrane as a gas-liquid contactor for waste gas treatment (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 45 (1995), S. 107-115 
    Details
    ISSN: 0006-3592
    Keywords: biofilm ; waste gas treatment ; hydrophobic microporous membrane ; mass transfer ; propene ; Xanthobacter ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A novel type of bioreactor for waste gas treatment has been designed. The reactor contains a microporous hydrophobic membrane to create a large interface between the waste gas and the aqueous phase. To test the new reactor, propene was chosen because of its high air/water partition coefficient, which causes a low water concentration and hampers its removal from air. Propene transfer from air to a suspension of propene-utilizing Xanthobacter Py2 cells in the membrane bioreactor proved to be controlled by mass transfer in the liquid phase. The resistance of the membrane was negligible. Simulated propene transfer rates agreed well with the experimental data. A stable biofilm of Xanthobacter Py2 developed on the membrane during prolonged operation. The propene flux into the biofilm was 1 × 10-6 mol m-2 s-1 at a propene concentration of 9.3 × 10-2 mol m-3 in the gas phase. © 1995 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260450203
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