Research On Bacteriostasis And Bioremediation,Detection Of Toxic Substances In Environment Using Electroanalytical Techniques

Piezoelectric quartz crystal has been applied to numerous fields such as analytical chemistry, biochemistry, environmental monitoring, life science and molecular biology because of its advantages such as high sensitivity, broad sensing-spectrum, simple construction and low cost. The electrochemical technique, especially voltammetry, has been used for environmental analysis due to their high sensitivity, ease of application, low cost, high selectivity and accuracy. Based on the high sensitivity response of electroanalytical techniques to the substance of solution, this thesis presents theoretical and applied studies for biomediation and detection of toxic substance in the environment as follows:1. The growth condition of Pseudomonas aeruginosa was monitored by the sensitive response of a Series Piezoelectric Quartz Crystal (SPQC) to the conductivity of solution. Combined with the dimethoate concentration detected by High Performance Liquid Chromatography (HPLC), the dynamic process of dimethoate degradated by Pseudomonas aeruginosa was studied. Meantime, a combined system response model, for microorganism reduction kinetics at pesticide was derived and proved based on the novel system.2. Based on the characteristics of Pseudomonas aeruginosa reduction hexavale chromium served glucose as carbon source, we firstly inspected P. aeruginosa reduction hexavale chromium common in the conditions of citrate in neutral.3. According to the changing of density/viscosity in the solution during the growth of bacteria, the inhibitory characteristics of Nisin to Staphylococcus aureus was studied with piezoelectric impedance analysis technique. Based on the relationship between the amount of Nisin and growth kinetic parameters (A,μm,λ), a new impedance response model reflecting this inhibition effect of Nisin towards Staphylococcus aureus was derived for the first time. And the potency of Nisin unknown was determined by the relationship between the concentration of Nisin and the maximum value of impedance response.4. A new electrochemistry method for determined dimethoate was proposed in this paper. According to the principle of dimethoate hydrolysis generated sulfhydryl in alkaline environment, dimethoate was determined in KOH at gold electrodes using gold nanoparticle enlarging electrochemical signals. The electrochemical deposition method was employed to obtain small sized and dispersed uniformly gold nanoparticles on the gold electrode surface with the aim of an improved analytical performance. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to evaluate the electrochemical behavior of the modified electrodes.