Effect of Direct Electric Current on the Cell Surface Properties of Phenol-Degrading Bacteria

Abstract

The change in cell surface properties in the presence of electric currents is of critical concern when the potential to manipulate bacterial movement with electric fields is evaluated. In this study, the effects of different direct electric currents on the cell surface properties involved in bacterial adhesion were investigated by using a mixed phenol-degrading bacterial culture in the exponential growth phase. The traits investigated were surface hydrophobicity (measured by adherence to n-octane), net surface electrostatic charge (determined by measurement of the zeta potential), and the cell surface shape and polymers (determined by scanning electron microscope analysis). The results showed that a lower current (less than 20 mA) induced no significant changes in the surface properties of phenol-degrading bacteria, that an electric current of 20 mA could increase the surface hydrophobicity and flatten the cell shape, and that a higher current (40 mA) could increase the surface extracellular substances and the net negative surface electrostatic charge. The results also revealed that the electric current effects on cell hydrophobicity varied with the suspending medium. We suggest that an electric current greater than 20 mA is not suitable for use in manipulation of the movement of the phenol-degrading bacteria, although such a current might favor the electrophoretic movement of the bacterial species.

Enhancement of Enzymatic Process by Electric Potential Application

“…Similar results were previously reported [8] for phenol degrading bacteria in the presence of high electric current. A bioelectrokinetic test suggested that bacterial inactivation might occur by interaction with the surfaces of the electrodes, resulting in cell wall or membrane degradation through oxidation or reduction.…”

“…A bioelectrokinetic test suggested that bacterial inactivation might occur by interaction with the surfaces of the electrodes, resulting in cell wall or membrane degradation through oxidation or reduction. The cell viability may be also affected, at high applied potential or induced field, by irreversible permeabilization of the cell membrane which results in direct oxidation or reduction of the cellular constituents [8,9].…”

Enhanced ex-situ bioremediation of soil contaminated with petroleum refinery waste effluents by biostimulation through electrokinetics and inorganic fertilizer

“…Similar observations have been reported [12,21,35]. Nevertheless, the pH across soil bed was generally maintained between 6.8 and 7.5 which were still favourable for the autochthonous microbial activity; this was possible due to regular reversal of current intensity [12,35].…”

“…Above the 3 days of remediation period, the pH started to increase gradually to 6.83, 7.0 and 7.25 near the anode section and began to decrease to 7.5, 7.6 and 7.7 near the cathode section while it increased to 7.21, 7.35 and 7.50 at 4 cm distance and 7.39, 7.45 and 7.56 at 7 cm distance, respectively, at the end of 15 days of remediation time. The variations in pH values (decrease and increase) observed around the anode section, 4 and 7 cm distances from anode and the cathode section may be due to the migration or movement of acidic and alkaline pH front from one electrode section to the other electrode section [21,35].…”

Effects of Electrical Stimulation on the Degradation of Azo Dye in Three-Dimensional Biofilm Electrode Reactors

“…At the same time, the surface of the GAC was rich in microorganisms and the formation of this biological cathode greatly reduced mass transfer resistance, facilitating electron transfer from the solution to the electrode [25], so that electrons could move with high efficiency, and the removal efficiency increased. However, high current (more than 20 mA) may inactivate the microorganisms [26] and cause them to fall off [27]. In our experiment, the removal efficiency increased when the external voltage rose from 0.5 to 2 V; the current rose from 0.68 to 1.83 mA; and we did not find microbial inactivation or fall-off.…”