(1. 東華大學 環(huán)境科學與工程學院，上海 201620；
2. 中南大學 資源加工與生物工程學院，長沙 410083)
摘 要: 采用離子可透過模型和不可透過模型，通過數(shù)值擬合的方法計算嗜酸氧化亞鐵硫桿菌的表面電荷密度、空間電荷密度、表面電位和道南電位等。Zeta電位測定結(jié)果表明：以硫為能源培養(yǎng)的細菌細胞等電點(IEP)高于報道的以亞鐵培養(yǎng)的細菌的。運用表面基團離子化模型模擬實驗數(shù)據(jù)得出：以硫培養(yǎng)的嗜酸氧化亞鐵硫桿菌的 IEP＞2，這主要是由細菌表面蛋白質(zhì)的氨基電離引起的。采用離子可透過模型分析表明：pH＜5時，細菌表面電位(φ0)和道南電位(φDON)下降較快；細菌表面的pH值等于細胞內(nèi)的pH(約6~7)后，細菌的φ0和φDon的變化漸緩；計算得到細菌表面的雙電層的厚度約為5 nm。細菌表面的雙電層將影響浸礦體系中離子遷移和營養(yǎng)物質(zhì)傳輸，而細菌彼此表面雙電層的相互作用對細菌聚集不利。
關鍵字: 雙電層；道南電位；離子可透過模型；軟顆粒
（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
