The main aim of this work is to develop a simple inhibition electrochemical sensor array for detection of heavy metals using bacteria. A series of electrical measurements (cyclic voltammograms) were carried out on samples of two types of bacteria, namely Escherichia coli and Shewanella oneidensis along with optical measurements (fluorescence microscopy, optical density, and flow cytometry) for comparison purposes. As a first step, a correlation between DC electrical conductivity and bacteria concentration in solution was established. The study of the effect of heavy metal ions (Hg2+) on DC electrical characteristics of bacteria revealed a possibility of pattern recognition of inhibition agents. Electrical properties of bacteria in solution were compared to those for immobilized bacteria. Keywords: Inhibition biosensor, Escherichia coli, Shewanella oneidensis, Optical measurements, Electrochemical measurements, Cyclic voltammogram