Changes in Surface Charge, Respiratory Rate and Stainability with Crystal Violet of Resting Escherichia coli B Cells Anaerobically Exposed to an Alternating Current

Abstract

Phosphate buffer suspensions of resting Escherichia coli B cells at pH 7.0 were anaerobically exposed to an alternating current (AC) of 50 Hz at a current density of 600 mA/cm² and 34±3°C. The AC-exposed cells required a higher concentration of a cationic flocculant, poly(methacryloxyethyl-trimethyl-ammonium chloride), to form cell floes than unexposed cells. The electrophoretic mobility of the cells increased after AC-exposure. Oxygen uptake by the exposed cells in a neutral reaction mixture decreased with increasing exposure time. The cells were less easily stained with crystal violet after AC-exposure. These observations show that AC-exposure causes an increase in the amount of the negative surface charge of E. coli cells and changes in some physiological properties.