Bacterial cells possessing a certain zeta potential are immobilized by electrochemical deposition within conducting polymers such as poly(3,4-ethylenedioxythiophene) (PEDOT) and polypyrrole (PPy). These conducting polymers serve as a biocompatible matrix for trapping bacteria on an indium-tin-oxide (ITO)-coated glass substrate. The biological functions of bacteria were not affected by the chemical structure and electrical conductivity of the matrix. The viability of the bacteria on the ITO glass was monitored by dark-field microscopy. The cell density of Escherichia coli increased logarithmically during incubation in nutrient broth medium, leading to definitive formation of a biofilm on PPy. The facultative E. coli anaerobe sustains metabolism under aerobic and anaerobic conditions, but proliferates more extensively in the presence of oxygen. The conducting PPy film also facilitates electrochemical evaluation of the respiratory activity of bacterial cells and establishes that facultative anaerobic and aerobic bacteria exhibit similar respiratory activities under aerobic conditions.