The effect of magnesium ions and Tris buffer on the uptake of cetyl trimethyl ammonium bromide by Escherichia coli

Publisher Website
Google Scholar
Abstract
The uptake of CTAB by E. coli from a glucose-free mineral salts medium occurs in two distinct phases. Increasing the magnesium ion content of the suspending medium emphasizes the diphasic nature of the isotherm. The primary phase is extended and the height of the “saturation” plateau of the secondary phase, as a function of CTAB uptake, is reduced. The CTAB uptake isotherm for E. coli suspended in water is not obviously diphasic and the maximum amount of CTAB taken up by the cells at “saturation” is less than that in medium. The height of this plateau is influenced by Tris buffer, an increase in the Tris concentration increasing the maximum CTAB uptake. A method for the rapid screening of uptake isotherms based on turbidity changes is also discussed.