Properties Of Whole Living Cell Blosensor And Metabolismic Dynamics Of E.Colis

Escherichia coli (E.coli) is kind of the most common bacteria, belongs to a facultative anaerobic type of bacteria, which aerobic respiration under the condition of aerobic respiration, and can anaerobic respiration or fermentation without oxygen. E. coli can survive in the hard environment conditions, and had been used as recognition components in biological sensors recent years, such as the whole living cell biosensor as biological recognition elements. The single enzyme biosensors only recognizes one component in the sample solution, but the whole living cells biosensor may be used to respond many components with different manners. In this thesis, the E.coli living cells were cultured and embedded in a carbon paste electrode and build up as a biosensor for detection glucose as a nutricent and lead ions as posion, and some results were reported as the followings.In the respiration or fermation in oxygen riched environments, E.coli releases hydrogen peroxide, which can be monitored sensitively by cyclic voltammetry on the carbon paste electrode. The biosensor shows one cathodic peak at-0.50 V. The metabolismic dynamics of glucose as nutrient by E. coli follows an exponential association model with an apparent first order rate constant of 0.01638 min-1. The poisoning dynamics of lead ion to E. coli follows a logistic model with an apparent first order rate constant of 0.0293 min-1. The sensor is very stable during the storagy and usage with a very long lifetime (70 days without loss of its bioactivity) due to the strong survivability of E. coli bacteria embedded in the carbon paste electrode.Monitoring metabolism kinetic process of glucose of biosensor by cyclic voltammetry, the cathodic peak current at-0.50 V exponential changed with contacting time, which gives the dynamic function of the metabolism of glucose, and used for the detection of glucose in solution. The peak current at the lowst point of the dynamic curve is linearly changed with glucose in solution, and the logarithmof characteristic time is proportional to the logarithm of glucose concentration, which can be used for the detection of glucose in solution.Fluorescence spectrometry was used for validating aerobic process of E.coli correlated with oxygen, and moniting the metabolismic dynamic process with an exponential association model in glucose. The fluorent results give the evidence for the electrochemical biosensor results about.