Influence of Cytoplasm Electrolyte Concentration on Maxwell−Wagner Polarizability of Bacteria E. coli

Abstract

The electric polarizability of bacteria is considered in the literature to have a surface charge dependent (ChD) and a Maxwell-Wagner (MW) mechanism. We distinguish experimentally both the types of interface polarizability by the frequency of the electric field and the medium electrolyte concentration. It was shown in a previous work ( Zhivkov , A. M. ; Gyurova , A. Y. Colloids Surf., B 2008 , 66 , 201. ) that the ChD component is shown up on the outer bacteria surface even at megahertz frequencies. The MW polarizability is studied in the present work in the range from 20 kHz to 20 MHz by change in the inner (cytoplasm) electrolyte concentration. The ion transport through the cytoplasmic membrane of alive and fixed by formaldehyde E. coli K12 is accelerated by adding of ethanol in low concentration. The frequency dependence and the kinetics of the electric polarizability and the size of the bacteria are investigated by conservative electric dichroism, based on the alteration of the optical density at orientation of the cells in electric field. The conclusion is that the internal MW component has the main contribution to the change in the total bacteria polarizability, as well as the external MW and the internal ChD components are not shown up.