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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 119 (1994), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract The periplasmic enzyme β-lactamase was selectively released from Escherichia coli K12 by the amphiphilic quaternary ammonium compound tetradecyl betainate at certain concentration intervals. At low concentrations little enzyme was released, and at high concentrations enzyme inactivation occurred. Greater effects of tetradecyl betainate were seen both with respect to release and inactivation at higher pH. At intermediate concentrations of tetradecyl betainate high yields of β-lactamase were obtained with no detectable contribution of the cytoplasmic marker β-galactosidase. The highest yields of β-lactmase activity were obtained when high concentrations of salt were added 1 min after permeation of the bacteria with tetradecyl betainate.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 91 (1992), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract The uptake of octyl ethanolamine (C8EA) by Pseudomonas pseudoalcaligenes was determined at pH 7.1–10.0. At pH 9.1 the total uptake was nearly three times higher, and at pH 10.0 four times higher than at pH 7.1. Also the initial rate of uptake was lowest at pH 7.1. At pH 7.1 five to ten times higher concentrations of C8EA were needed than at pH 9.1 to achieve the same degree of leakage of cytoplasmic constituents. The results support the hypothesis that penetration of the bacterial cytoplasmic membrane by C8EA in its uncharged form is favoured. This takes place particularly with high pH in the suspending medium. In the cytoplasm, the pH is lower, and C8EA becomes more protonated. This will prevent back diffusion, promote accumulation and enhance membrane interaction and toxicity at high pH.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An electronic particle counter has been used to estimate the disintegration by freeze-pressing baker's yeast. A counter threshold level which just yielded the maximum count for intact cells was selected. The conductivity of the suspending medium was chosen such that maximum counts were obtained. Under these conditions, the electronic counts agreed well with the visual counts. At a certain threshold level the maximum count was obtained at a lower resistivity (higher conductivity) in the suspending solution with the freeze-pressed suspension than with untreated cells, indicating that damage to the permeability barrier may occur without disruntion of the cell envelope.Fresh baker's yeast cells do not behave as nonconducting particles. This has to be taken into account when volume determinations with electronic particle counters are performed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Biochemical and Microbiological Technology and Engineering 2 (1960), S. 453-479 
    ISSN: 0368-1467
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new press (the X-press) has been developed for the disintegration of cells in the frozen state (mostly at -25°C). By forcing the frozen cells contained in a cylinder through a hole much smaller than the diameter of the cylinder but much larger than the size of the cells, a satisfactory disintegration can be obtained.By forcing the cells through the hole repeatedly rather than once, a higher degree of disintegration can be achieved. By making the receiver identical to the charge chamber, repeated operations are possible without uncoupling the press.The disintegrated material is very easily recovered - it is simply taken out of the press in the form of a cylinder containing the frozen, disintegrated material which is then easily homogenized.This principle has been found satisfactory for the disintegration of a large number of cells, viz. bacteria, yeasts, moulds, plant and animal cells and, with regard to biochemical questions, it has been found to be superior to existing methods which do not treat the bacteria in the frozen state. The mechanism of the disintegrating action is discussed.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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