芽孢杆菌SeRB-2还原亚硒酸盐的动力学研究

微生物还原亚硒酸盐的动力学研究具有重要的现实意义,可以为Se (IV)污染场地的微生物修复设计提供理论依据。本文研究了兼性厌氧菌Bacillus sp.SeRB-2对亚硒酸钠的还原动力学。通过指数方程模型、对数方程模型和米氏方程模型的分析可知,Se (IV)的细菌还原符合一级反应动力学,还原反应主要集中在对数期和稳定生长前期,米氏方程模型能更好的反映细菌对亚硒酸盐的还原过程。通过对不同Se (IV)浓度下的米氏常数(K_m)和最大反应速率(V_max)的分析发现,当Se (IV)浓度较低时,K_m值较小,V_max值较大,这表明Se (IV)浓度越低,还原亚硒酸盐的酶与Se (IV)的结合能力越强,此时细菌对亚硒酸盐的还原速率越大、还原效率也越高。在本研究中,当Se (IV)浓度为1 mmol/L时,其还原效率最高可达90%,能够有效去除或降低Se (IV)污染,说明该菌在Se (IV)污染场地的生物修复上具有应用潜力。

Study on Kinetics of Selenite Reduction by Bacillus sp. SeRB-2

It is significant to study the bioreduction kinetics of selenite, which may provide a theoretical basis for bioremediation design in the contaminated sites. The kinetics of Se(IV) reduction by facultative anaerobic strain Bacillus sp. SeRB-2 was studied using the index equation model, logarithm equation model and Michaelis-Menten equation model. It is shown that Se(IV) bioreduction fits a first-order reaction, and reacts mainly in the logarithmic phase and early stationary phase. The Michaelis-Menten equation model better reflects the reduction process compared with both index and logarithm equation models. The kinetic parameters K_m and V_max acquired were relevant to Se(IV) concentrations, i.e., the lower the Se(IV) concentrations, the smaller the K_m value and the hither V_max will be. It is indicated that the binding ability between Se-(IV)-reducing enzyme and selenite is stronger, the reducing rate is larger and the reducing efficiency is higher, in a lower Se(IV) medium. In addition, the reduction efficiency is up to 90%, when Se (IV) concentrations are about 1mmol/L, which illustrates that Se(IV) contamination can be effectively reduced or removed by strain SeRB-2. This strain may be suitable for bioremediation in the Se(IV) contaminated sites.