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).
[Show abstract][Hide abstract] 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 05/2013; 11(5). DOI:10.2478/s11532-013-0220-9 · 1.33 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Aqueous solutions containing both four-tailed oligoglycine [Gly(7)-NHCH2-](4)C and lipopolysaccharides (Ra-LPS from Escherichia coli EH100) are studied in the present work. The experimental procedure comprises examination of the properties of interfacial layers at the solution/air boundary and the drainage characteristics of microscopic foam films. Significant decrease of the dynamic and equilibrium surface tension values is established upon raising the content of the oligoglycine in the mixture. This effect is related to the plausible formation of amphiphilic LPS/tectomer complexes. The drainage properties of the films go in line with the notion for the possible onset of amphiphilic entities in the solutions. The reported data may be regarded as experimental evidences for the existence of surface active LPS/tectomer complexes in the investigated systems. The results suggest that aqueous solutions of four-antennary olygoglycines could be used for registration of trace quantities and efficient capture of LPS in aqueous media.
Colloids and Surfaces A Physicochemical and Engineering Aspects 10/2014; 460:130-136. DOI:10.1016/j.colsurfa.2014.01.079 · 2.75 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Struvite and carbonate apatite are the main components of the so-called infectious urinary stones, which are the result of the activity of microorganisms producing urease, mainly from Proteus species. The aggregation of precipitating particles and bacteria is suspected to be one of the primary causes for urinary stone formation. In the present study struvite, carbonate apatite and bacteria are characterized by zeta potential and on this basis their aggregation in artificial urine is studied. The results demonstrate that struvite, carbonate apatite and bacteria show negative zeta potential. Additionally, on the basis of the results it may be stated that from these three components carbonate apatite has the greatest ability to the aggregation.
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