Comparison of the behavior of negative electrically charged E. coli and E. faecalis bacteria under electric field effect

Abstract

The negative electrical charge of Escherichia coli and Enterococcus faecalis bacteria is an indication that they can be affected by an electric field. To show that the movements of electrically charged bacteria can be controlled, impedance spectroscopy method was used on a porous silicon (PS) structure with 60 % porosity and 7-12 μm pore size. The main purpose of this study is to use the electric charge of these two bacterial species to bring bacteria closer to the sensors with the help of an electric field, and to compare the behavior of these bacterial species in the process. The effect of bacterial contact on porous silicon surface impedance spectra was studied under electrical fields between 0 and 5 kV/cm at a constant bacterial concentration. It was observed that both bacteria can be approximated to the PS surface by the electric field effect. However, the shape and dimensional differences of these two bacterial species caused differences both in their movements in the electric field and in their settlement on the PS surface, and these differences were interpreted. In addition, similar experiments were repeated for dead bacteria and it was determined that the electric field control was not the same as for living bacteria.

Keywords: E. coli; E. faecalis; Electric field; Impedance spectroscopy; Porous silicon.