Influence of low concentration ethanol on membrane permeability of e.coli

Abstract

The electric polarizability of bacteria gives information about their structure and functional state and can be measured electro-optically by orientation of the cells in electric field. The interface polarizability is two kinds: charge dependent (ChD) and Maxwell-Wagner (MW). ChD polarizability depends on the surface charge and the thickness of double electric layer. MW polarizability is determined by the electric properties of the cytoplasm and the membrane (their conductivity and dielectric permittivity). It is known that the bacteria polarizability decreases significantly by adding of ethanol; however the reason for that change is not clear. In the present work we investigate the influence of low concentration of ethanol on the polarizability of Escherichia coli K12. The results show up that the effect of ethanol is related to the cytoplasm MW polarizability which change is due to increasing the cell membrane permeability. This affect on the ionic flow through the membrane, which velocity and direction depends on the relative values of the cytoplasm and the extracellular medium ionic strength. © 2009 Taylor and Francis Group, LLC.