(1. 东华大学 环境科学与工程学院，上海 201620；
2. 中南大学 资源加工与生物工程学院，长沙 410083)
摘 要: 采用离子可透过模型和不可透过模型，通过数值拟合的方法计算嗜酸氧化亚铁硫杆菌的表面电荷密度、空间电荷密度、表面电位和道南电位等。Zeta电位测定结果表明：以硫为能源培养的细菌细胞等电点(IEP)高于报道的以亚铁培养的细菌的。运用表面基团离子化模型模拟实验数据得出：以硫培养的嗜酸氧化亚铁硫杆菌的 IEP＞2，这主要是由细菌表面蛋白质的氨基电离引起的。采用离子可透过模型分析表明：pH＜5时，细菌表面电位(φ0)和道南电位(φDON)下降较快；细菌表面的pH值等于细胞内的pH(约6~7)后，细菌的φ0和φDon的变化渐缓；计算得到细菌表面的双电层的厚度约为5 nm。细菌表面的双电层将影响浸矿体系中离子迁移和营养物质传输，而细菌彼此表面双电层的相互作用对细菌聚集不利。
关键字: 双电层；道南电位；离子可透过模型；软颗粒
（1. College of Environmental Science and Engineering, Donghua University, Shanghai 201620, China;
2. School of Resources Processing and Bioengineering, Central South University, Changsha 410083, China）
Abstract:The surface charge density, space charge density, surface potential (φ0) and Donnan potential (φDon) on the surface of Acidithiobacillus ferrooxidans cultivated with elemental sulfur (S-A.ferrooxidans) were calculated by numerical simulation using the ion-impenetrable and ion-penetrable models. Zeta potential measurement show that the isoelectric point (IEP) of S-A.ferrooxidans is higher than that of bacterium cultured with Fe2+. It is concluded from fitting data by ionizable surface group model that S-A.ferrooxidans surface probably consists of much proteins, the ionization of amino group of which causes higher IEP (＞2). The ion-penetrable model reveals that φ0 and φDon decrease rapidly at pH＜5 but hardly change when pH is 6−7. The thickness of electrical double layer of S-A.ferrooxidans is estimated as 5 nm. The electrical double layer of bacterial cell surface may have significant implications for ions transfer and nutrient transport, but their interaction is unfavorable for bacterial aggration.
Key words: electrical double layer; Donnan potential; ion-impenetrable model; soft particle
