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The effect of composition of the core region of Escherichia coli K-12 lipopolysaccharides on the surface properties of cells

Microbiology (Impact Factor: 0.65). 05/2008; 77(3):293-297. DOI: 10.1134/S0026261708030077

ABSTRACT The pH dependences of electrokinetic potentials (EKP) of the cells of two Escherichia coli K-12 strains (D21 and JM 103) with known lipopolysaccharide (LPS) core composition have been determined by the method of
microelectrophoresis. At pH 4.6–5.2, the negative surface charge of the cells with Re core LPS was reliably higher. It was
shown that the interaction of bacteria with lysozyme results in a decrease of optical density of suspensions due to higher
sensitivity of the cells with complete LPS core to hypotonic shock. LPS release from bacterial cell wall depended also on
bacterial LPS core composition and increased with LPS core extension. Electrokinetic measurements and the study of the interaction
of cells with lysozyme suggest that higher negative surface charge of E. coli JM 103 cells (Re type LPS) is associated with higher quantity and density of LPS packing in the cell wall as compared with
the cells of E. coli D21 (Ra type LPS).

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    ABSTRACT: The electric properties of bacteria determine their non-specific interactions with the environment, in particular their pathogenic activity. The electric polarizability of Escherichia coli HB101 (K-12 strain) was studied while inactivation with ethanol (20–40 vol.%). The current investigation might be regarded as a continuation of previous research on the polarizability of E. coli at lower ethanol concentration (≤ 20 vol.%) and higher frequencies (≥ 20 kHz). The bacteria polarizability at low frequencies (<104 Hz) shows anomalies (unexpected increase in the polarizability at certain ethanol concentrations), while the parameter decreases with an increase in the ethanol concentration at higher frequencies. We investigated for the possible reasons causing the anomalies — in our case reduced to the medium dielectric permittivity, the average cell length and the surface electric charge density distribution, related to bacterial lipopolysaccharides. We suggest a hypothesis for the molecular mechanism of changing the surface charge of E. coli, carried by lipopolysaccharides, induced by the non-ionic ethanol.
    Central European Journal of Chemistry 11(5). · 1.17 Impact Factor