温度和电子传递体AQDS对铁还原细菌Shewanella putrefaciens CN32矿化产物的影响

摘要

The superparamagnetic (SP) magnetite produced by microorganism is an important source of magnetic minerals in sediments and soils. To investigate the behavior of the biomineralization, we compared the reduction of hydrous iron oxide and the formation of magnetite by iron reducing bacteria Sheivanella putrefaciens CN32 at different temperatures (20℃, 30℃,37℃). It was observed that after the addition of bacteria to the system, the Eh began to decrease quickly while the pH and the concentration of ferrous increased, and the formation of magnetite started. Transmission electron microscopy observation and magnetic hysteresis loop of room temperature show that superparamagnetic magnetite was produced. Comparing the variations of susceptibility and isothermal remanent magnetization in different conditions suggests that temperature is the most important factor influencing the biomineralization, the increase of the temperature accelerated the mineralization. The fact that coercivity increased with the temperature and low temperature magnetic measurement suggests that the average blocking temperature (Tb) of the magnetite increased from 95K at 20℃ to 160K at 37℃ , both indicating that the size of the particles increased. Also the addition of AQDS (2, 6-anthraquinone disulphonate) as the electron shuttle accelerated the biomineralization by CN32. These results help us to understand the biomineralization capability of iron reducing bacteria and their contribution to the environmental magnetism.%微生物矿化产生的超顺磁性(SP)磁铁矿是沉积物和土壤中磁性矿物的重要来源.本文比较了三个不同温度下(20℃,30℃,37℃)纯培养铁还原细菌Shewanella putre aciens CN32还原水合氧化铁形成SP磁铁矿的矿化特征.在实验体系中加入细菌CN32后,体系的氧化还原电位Eh迅速下降,酸碱度pH和亚铁离子Fe2浓度随之快速上升,磁铁矿也逐渐开始形成.透射电镜观测和窒温磁滞回线测定表明产物为SP磁铁矿特征.对比三个温度下产物的磁化率和饱和磁化强度变化发现,培养温度是影响细菌CN32矿化的重要因素,温度升高加快了细菌矿化.随培养温度的升高,磁铁矿的矫顽力增大；低温磁学测量结果显示,产物SP磁铁矿颗粒的平均解阻温度Tb从20℃时的95 K升高到37℃时的160 K,都表明生成的磁铁矿的粒径随培养温度的升高而增大.另外,实验体系中加入电子传递体(AQDS,2,6-anthraquinone disulphonate)明显促进了CN32矿化.这些实验模拟结果有助于认识自然环境中铁还原细菌矿化产生磁性矿物的能力和贡献.