Microbial Fuel Cell (MFC) power production and Microbial Electrolysis Cell (MEC) organic production depend strongly on their dynamic environment conditions, like inlet substrate concentration, temperature, etc. This work presents a discrete extremum seeking controller to quickly tune the MFC and MEC electrical settings in order to achieve maximum performance irrespective of these dynamic environment conditions using the successive parabolic interpolation iteration scheme. The controller converges in about 3.5 days within 5% of the cell's maximum performance and in about 5.4 days within 1% for an established MFC model. The proposed discrete parabola controller converges 3x faster than the state-of-theart controllers without requiring a time-consuming calibration procedure. Equally fast convergence speed is achieved on a MEC model.