中文摘要：

以嗜酸氧化亚铁硫杆菌（Acidthiobacillus ferrooxidans,简称At.f菌,FN811931）为研究对象,探讨了Mg^2＋对其氧化活性的影响规律,并采用Zeta电位及红外光谱分析,考察了其影响的内在机制.结果表明：在Mg^2＋质量浓度小于5.0g/L的体系中,培养35h时,p H值从培养初期的2.00左右下降到1.70左右,氧化还原电位从培养初期的390 m V左右上升到600 m V以上,Fe^2＋氧化率接近100%,细菌生长达到旺盛期;当Mg^2＋质量浓度超过5.0 g/L时,体系p H值下降速率、氧化还原电位上升速率、Fe^2＋氧化率、细菌生长速率均降低,且Mg^2＋质量浓度越大,影响效果越显著.Zeta电位测试结果表明,20.0 g/L镁离子作用下细菌等电点为3.6,高于9K培养基中细菌的等电点2.7,这从宏观上解释了细菌细胞壁结构的变化;红外光谱测试结果显示,Mg^2＋作用下,细菌细胞壁中的官能团发生了交联作用,导致吸收峰N—H的消失和—OH、—C‖O、—CH3、—CH2、—P‖O、—CN的偏移,致使细胞壁表面蛋白质结构发生变化,进而影响了细菌的氧化活性.

英文摘要：

By taking acidophilic bioleaching bacteria （Acidthiobacillus ferrooxidans, At. f for short） as the research objective, this paper discusses the effect of Mg^2＋ on the oxidation activity of At. f and analyzes the corresponding in- ternal mechanism by means of Zeta potential and infrared spectroscopy. The results indicate that, when the mass concentration of Mg^2＋ is less than 5.0 g/L, after a cultivation for 35 h, the pH value of the system decreases from 2.00 to 1.70, the oxidation reduction potential increases from 390mV to more than 600mV, the Fez＋ oxidation rate is up to 100%, and the bacteria are in an exuberant growth period ; and that, when the mass concentration of Mg^2＋ is more than 5.0 g/L, the reduction rate of pH value, the rise rate of the oxidation reduction potential, the oxida- tion rate of Fe^2＋ and the bacteria growth rate all decrease, and the decreasing rate is positive to the mass concentra- tion of Mg^2＋ Zeta potential tests show that the bacteria isoelectric point is 3.6 under the action of 20. 0 g/L magne- sium ions, which is higher than that of the bacteria cultivated in 9K medium, namely 2.7. This is the macroscopic cause of the structure variation of bacterial cell walls. Moreover, IR results show that, under the action of magne- sium ions, the functional groups of the bacterial cell walls crosslink, which results in the disappearance of N--H absorption peak as well as the migration of -OH, --C = O, -CH3, -CH2, -P = O and --CN. Thus, the structure of the cell surface protein changes and the oxidation activity of bacteria decreases.