Increasing the ionic strength of the electrolyte in a microbial fuel cell (MFC) can remarkably increase power output due to the reduction of internal resistance. However, only a few bacterial strains are capable of producing electricity at a very high ionic strength. In this report, we demonstrate a newly isolated strain EP1, belonging to Shewanella marisflavi based on polyphasic analysis, which could reduce Fe(III) and generate power at a high ionic strength of up to 1,488 mM (8% NaCl) using lactate as the electron donor. Using this bacterium, a measured maximum power density of 3.6 mW/m(2) was achieved at an ionic strength of 291 mM. The maximum power density was increased by 167% to 9.6 mW/m(2) when ionic strength was increased to 1,146 mM. However, further increasing the ionic strength to 1,488 mM resulted in a decrease in power density to 5.2 mW/m(2). Quantification of the internal resistance distribution revealed that electrolyte resistance was greatly reduced from 1,178 to 50 Omega when ionic strength increased from 291 to 1,488 mM. These results indicate that isolation of specific bacterial strains can effectively improve power generation in some MFC applications.