Hypotheses

If bacteria in a MFC metabolize the substrates (in an aqueous solution) found in a MFC then the electrical output will spike significantly from the negative control of autoclaved dirt and the positive control of regular soil because as bacteria metabolizes substrates they will create organic acids in a fermentative process generating a shift from chemical energy to electrical energy.
If a MFC contains isolated bacteria from the electrodes of a MFC then it will produce more electrical output than isolated bacteria not found in a MFC because the bacteria found on the electrodes of a MFC will have specialized functions to contribute to the net increase of electron flow (current) of a MFC.
If a MFC contains multiple colonies of bacteria in a MFC then it will produce higher spikes in current of a MFC than isolated bacteria because the colonized bacteria with have more interaction between multiple colonies creating higher production of electrical energy.