Electrolytic stimulation of bacteria Enterobacter dissolvens by a direct current

The effects of a weak electric field on the growth and metabolic behavior of Enterobacter dissolvens were investigated using glucose as the sole carbon source. A direct current (DC) was applied using salt bridge electrodes and platinum electrodes. The best stimulating effects in terms of cell growth and the dehydrogenase activity (DHA) were obtained when a DC of 10 mA was applied for 12 h via the platinum electrodes. In this case, the electrolysis of water was the major electrode reaction, as determined by cyclic voltammetry. The presence of the hydrogen generated a strong reductive environment and led to a reduction of NAD/NADH ratio from 7 to 3. The specific activity of dehydrogenase and glucose consumption increased 2- and 1.5-fold, respectively. The application of the DC via the platinum electrodes also led to accelerated cell death during the later stationary phase. This is possibly due to the presence of anodic intermediates including H2O2, OHcenter dot and O-2(center dot). These results provide more details for understanding the effect of a DC on E. dissolvens, a strain with potential application in the electro-remediation of PAHs contaminated soil. (c) 2005 Elsevier B.V. All rights reserved.