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  • Title: A comparison between the elemental surface compositions and electrokinetic properties of oral streptococci with and without adsorbed salivary constituents.
    Author: van der Mei, Genet MJ, Weerkamp AH, Rouxhet PG, Busscher HJ.
    Journal: Arch Oral Biol; 1989; 34(11):889-94. PubMed ID: 2610623.
    Abstract:
    In order to characterize the functional cell surface, isoelectric points and elemental surface concentration, the ratios of nitrogen, oxygen and phosphorus to carbon of saliva-coated strains were determined by pH-dependent zeta potential measurements and X-ray photoelectron spectroscopy and compared with those of uncoated strains. The measurements of potential were carried out on completely hydrated cells, whereas the spectroscopy was on freeze-dried micro-organisms. The small increase in the nitrogen:carbon surface concentration ratio of saliva-coated streptococci in comparison to uncoated strains varied from 0.001 (Streptococcus mitis BA) to 0.029 (Streptococcus sanguis CH3) and was concurrent with an increase of the isoelectric point, ranging from 0.0 to 0.9. Increases in the oxygen:carbon ratio ranged from 0.006 (Strep. mitis BA) to 0.041 (Streptococcus mutans NS), whereas the phosphorus:carbon surface concentration ratio was unchanged after saliva treatment. Despite the fact that isoelectric and compositional measurements were made in different states of surface hydration, a decrease in the nitrogen:carbon ratio accompanied by an increase in oxygen:carbon ratio, was related to a decrease of the isoelectric point of the saliva-coated strains, and so analogous with previous observations for uncoated strains. Although there were changes in the physico-chemical properties of the strains upon saliva coating, all more or less kept their own surface identity despite adsorption of salivary constituents, possibly indicating some capacity to protect their own physico-chemical identity.
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