Geobacter-based microbial fuel cells are becoming increasingly viable as a source of alternative energy. Current research and commercial application have been slowed by the inability of Geobacter species to tolerate the presence of oxygen. Oxidative stress protection enzymes normally play a key role in protecting cells from oxygen damage. This project hypothesizes that the over-expression of two important oxidative stress protection enzymes, catalase and superoxide dismutase, can increase aerotolerance. These genes were amplified from the genome of Geobacter sulfurreducens and cloned into plasmid pRG5 behind the ptaclac promoter. This plasmid was transformed into both E. coli and G. sulfurreducens to examine oxygen tolerance, gene expression, and enzyme activity. Preliminary data show increases in enzyme activity in E. coli and an increase in aerotolerance in G. sulfurreducens for both genes. This seems to be the first example of an increase in an obligate anaerobe's aerotolerance due to the intentional introduction of oxidative stress genes.