'Soft-particle' analysis of the electrophoretic mobility of a fibrillated and non-fibrillated oral streptococcal strain: Streptococcus salivarius

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    Abstract

    The electrophoretic mobility of microbial cell surfaces can be analysed in terms of a so-called soft layer model, in which the electrophoretic mobility is described as originating from the potentials over the surface charge layer and the membrane fixed charges. Often, the polyelectrolyte layer deforms under the influence of ionic strength variations. In the soft layer analysis of electrophoretic mobilities this is expressed in the softness 1/lambda. Here, we determined the softness of two oral streptococcal strains, S. salivarius HE and HBC12 from particulate microelectrophoresis in KCl solutions of varying ionic strength. Electron microscopy of negatively-stained organisms and X-ray photoelectron spectroscopy showed that strain HE had several classes of proteinaceous fibrils with lengths up to 178 nm on its outermost surface, while variant HBC12 had a bald, peptidoglycan-rich outer surface. The fibrillated strain HE appeared as relatively soft (1/lambda equals 1.4 nm) from analysis of its electrophoretic mobility, while the bald variant HBC12 was hard (1/lambda equals 0.7 nm) due to its comparatively rigid, peptidoglycan-rich outer surface, characteristic to Gram-positive bacteria. The presence of proteinaceous fibrils on strain HE slightly shielded the membrane fixed charges on HBC12. (C) 1998 Elsevier Science B.V. AU rights reserved.

    Original languageEnglish
    Pages (from-to)251-255
    Number of pages5
    JournalBiophysical Chemistry
    Volume74
    Issue number3
    Publication statusPublished - 14-Sept-1998

    Keywords

    • electrophoretic mobility
    • streptococci
    • surface structures
    • softness of polymer layer
    • RAY PHOTOELECTRON-SPECTROSCOPY
    • SURFACE CHARACTERISTICS
    • PROTEIN ANTIGENS
    • CELL
    • MUTANTS
    • MICROORGANISMS
    • ADHESION
    • HB

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