Electrostatic Behavior of the Charge-Regulated Bacterial Cell Surface

The electrostatic behavior of the charge-regulated surfaces of Gram-negative Escherichia coli and Gram-positive Bacillus brevis was studied using numerical modeling in conjunction with potentiometric titration and electrophoretic mobility data as a function of solution pH and electrolyte composition...

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Bibliographic Details
Published in:Langmuir 2008-05, Vol.24 (9), p.5003-5009
Main Authors: Hong, Yongsuk, Brown, Derick G
Format: Article
Language:English
Subjects:
Bacillus - chemistry
Bacillus brevis
Biopolymers - chemistry
Cell Wall - chemistry
Chemistry
Colloidal state and disperse state
Electrolytes
Escherichia coli
Escherichia coli - chemistry
Exact sciences and technology
General and physical chemistry
Hydrogen-Ion Concentration
Static Electricity
Surface physical chemistry
Surface Properties
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Summary:The electrostatic behavior of the charge-regulated surfaces of Gram-negative Escherichia coli and Gram-positive Bacillus brevis was studied using numerical modeling in conjunction with potentiometric titration and electrophoretic mobility data as a function of solution pH and electrolyte composition. Assuming a polyelectrolytic polymeric bacterial cell surface, these experimental and numerical analyses were used to determine the effective site numbers of cell surface acid−base functional groups and Ca2+ sorption coefficients. Using effective site concentrations determined from 1:1 electrolyte (NaCl) experimental data, the charge-regulation model was able to replicate the effects of 2:1 electrolyte (CaCl2), both alone and as a mixture with NaCl, on the measured zeta potential using a single Ca2+ surface binding constant for each of the bacterial species. This knowledge is vital for understanding how cells respond to changes in solution pH and electrolyte composition as well as how they interact with other surfaces. The latter is especially important due to the widespread use of the Derjaguin−Landau−Verwey−Overbeek (DLVO) theory in the interpretation of bacterial adhesion. As surface charge and surface potential both vary on a charge-regulated surface, accurate modeling of bacterial interactions with surfaces ultimately requires use of an electrostatic model that accounts for the charge-regulated nature of the cell surface.
ISSN:0743-7463
1520-5827
DOI:10.1021/la703564q