A CHEMICALLY MEDIATED AMPEROMETRIC BIOSENSOR FOR MONITORING EUBACTERIAL RESPIRATION

The development of a novel biosensor system for measuring the respiratory activity of whole eubacterial cells is described. The biosensor incorporates a physically immobilized layer of cells held in intimate contact with an amperometric transducing electrode and uses a chemical mediator, potassium ferricyanide, to divert electrons from the respiratory system of the bacteria to the poised electrode. The current thus produced is proportional to the level of respiratory activity of the immobilized bacterial cells and can be monitored by a computer interface system. The paper outlines the principles of the biosensor and describes the results of a screen of potentially useful eubacteria. Also described are the effects of physical parameters on the sensor and a strategy for the long term preservation of the biosensor by freeze-drying.