Isolation, Identification Of Methyl Tert-Butyl Ether-Aerobiosis Degradation Strain And Its Degradation Kinetics

Methyl tert-Butyl Ether(MTBE) which can melt in gas well has high research octane number, and is used as a gasline addition to replace alkyl lead. As a result of its widespread use, and its very water-solubility, MTBE can move in the environment almost as fast as groundwater, with practically no retardation due to sorption on soil particles. The studies on the toxicology of MTBE indicated that MTBE was not only an animal carcinogen but also a possible human carcinogen. Biodegradation of MTBE by culture A₁ which can use MTBE as the sole carbon source to grow under aerobic condition in some concentration extension was studied in this paper, and the main factors such as inoculation amount of microbes, pH, temperature , MTBE concentration, heavy metals and cometabolic substrates that may affect the degradation efficiency of MTBE were further studied. Kinetic, mechanism and the. degradation pathway of biodegradation by culture A₁ have been proposed, and the main results are as follows:1) A methyl tert-butyl ether degradation strain A₁ was isolated from the soil under an old Gingko tree. It was identified preliminarily as Comamonas testosteroni by 16Sr DNA scquence analysis.2) The optimum conditions were as following: pH 7.0, temperature 25℃, inoculation amount of microbes was 2ml (OD600=2.523A), initial MTBE concentration 50 mg/L. The results showed that the presence of Al³⁺ or Ba²⁺offers a significantly stimulating effect on MTBE degradation; howerve, Pb²⁺ or Cu²⁺ resulted in less biodegradation at metal concentrations of 2mg·L^-1, and the inhibitory effect was obivious with constantly decreasing value of MTBE degradation rate in the following order Cu²⁺> Pb²⁺. Another, the addition of ethanol as cometabolic substrate could increase the biomass and promote the biodegradation ability; howerer, the presence of toluene would restrain the degradation rate.3) The biodegradation process of MTBE can be well describeibed by enzymatic reaction of high concentration inhibition, with the maximum substrate ultilization rate 0.872d^-1, Michaelis-Menten constant 7.832 mg·L^-1, inhibitory constant 130.75 mg·L^-1 respectively. And the equation of MTBE degradation by culture A₁ is written as:r_i=0.872/1+7.832/C+C/130.75...