Activity and viability of polycyclic aromatic hydrocarbon-degrading Sphingomonas sp LB126 in a DC-electrical field typical for electrobioremediation measures

There has been growing interest in employing electrobioremediation, a hybrid technology of bioremediation and electrokinetics for the treatment of contaminated soil. Knowledge however on the effect of weak electrokinetic conditions on the activity and viability of pollutant-degrading microorganisms is scarce. Here we present data about the influence of direct current ( DC) on the membrane integrity, adenosine triphosphate (ATP) pools, physicochemical cell surface properties, degradation kinetics and culturability of fluorene-degrading Sphingomonas sp. LB126. Flow cytometry was applied to quantify the uptake of propidium iodide ( PI) and the membrane potential-related fluorescence intensities (MPRFI) of individual cells within a population. Adenosine tri-phosphate contents and fluorene biodegradation rates of bulk cultures were determined and expressed on a per cell basis. The cells' surface hydrophobicity and electric charge were assessed by contact angle and zeta potential measurements respectively. Relative to the control, DC-exposed cells exhibited up to 60% elevated intracellular ATP levels and yet remained unaffected on all other levels of cellular integrity and functionality tested. Our data suggest that direct current (X = 1 V cm(-1); J = 10.2 mA cm(-2)) as typically used for electrobioremediation measures has no negative effect on the activity of the polycyclic aromatic hydrocarbon (PAH)-degrading soil microorganism, thereby filling a serious gap of the current knowledge of the electrobioremediation methodology.