苏云金芽孢杆菌壁膜结构与钠长石界面作用机制

Interaction mechanism between Bacillus thuringiensis cell-wall membrane structure and albite

摘要:

背景 微生物壁膜结构(cell-wall membrane structure, CWMS)在生物诱导矿化和生物浸矿中发挥着重要作用。目的 探究苏云金芽孢杆菌(Bacillus thuringiensis) JT壁膜结构与钠长石界面作用机制以揭示其在硅酸盐矿物分解中的作用。方法 通过液相色谱-质谱联用(liquid chromatography-mass spectrometry, LC-MS)、傅里叶变换红外光谱(Fourier transform infrared spectroscopy, FTIR)和X射线光电子能谱(X-ray photoelectron spectroscopy, XPS)鉴定菌株JT壁膜成分，利用接触角、Zeta电位、FTIR、XPS探究钠长石与壁膜结构作用前后的表面结构、润湿性、电性，采用密度泛函理论(density functional theory, DFT)计算壁膜小分子片段与钠长石表面的吸附构型、态密度、电荷密度、Mulliken布居。结果 菌株JT壁膜结构含有N-乙酰葡萄糖胺(N-acetylglucosamine, NAG)、N-乙酰胞壁酸(N-acetylmuramic acid, NAM)、磷酸(phosphoric acid, PA)、丙三醇、甘氨酸(glycine, Gly)、D-谷氨酸(D-glutamic acid, D-Glu)和D-丙氨酸(D-alanine, D-Ala)等物质，与钠长石吸附作用强弱为NAM>PA>丙三醇>NAG>D-Glu>Gly>D-Ala。其中，NAG、NAM、PA和丙三醇羟基H与钠长石表面O形成共价键，Gly和D-Glu氨基H通过氢键与表面O发生作用，NAG、NAM、丙三醇羟基O、NAM羰基O、PA双键O、Gly、D-Glu和D-Ala羧基O与表面Al形成配位键，NAG、NAM、丙三醇的含氧基团、磷酸基团与表面硅羟基之间存在氢键。吸附作用导致钠长石晶胞Si-O和Al-O伸长，晶胞骨架疏松，钠离子得以释放，同时使钠长石表面结构、润湿性、电性发生改变。特别地，NAM的羟基和羰基优先作用于钠长石表面，以此为锚点，壁膜结构其余成分随之与其作用。结论 研究了菌株JT壁膜结构与钠长石界面作用机制，为微生物促进硅酸盐矿物分解提供理论基础。

Abstract:

Background Microbial cell-wall membrane structure (CWMS) plays a vital role in microbial-induced mineralization and bioleaching.Objective To reveal the interaction mechanism of Bacillus thuringiensis (JT) CWMS with the albite surface and elucidate the impact during decomposition of silicate minerals.Methods The components of JT CWMS were identified through LC-MS, FTIR, and XPS. The surface wettability, charge, and structure of albite before and after interaction with the CWMS were explored by contact angle measurements, potential analysis, and FTIR and XPS, respectively. DFT calculations were employed to study the adsorption configurations, density of states, charge density, and Mulliken population of small molecular fragments of JT CWMS on the albite surface.Results The JT CWMS contained N-acetylglucosamine (NAG), N-acetylmuramic acid (NAM), phosphoric acid (PA), glycerol, glycine (Gly), D-glutamic acid (D-Glu), and D-alanine (D-Ala). The adsorption strength followed the trend of NAM>PA>glycerol>NAG>D-Glu>Gly>D-Ala. The hydroxyl H of NAG, NAM, PA, and glycerol formed covalent bonds with the O atoms on the albite surface. The amino H of Gly and D-Glu interacted with the O atoms on the surface through hydrogen bonding. The hydroxyl O of NAG, NAM, and glycerol, the carbonyl O of NAM, the double-bond O atom of PA, and the carboxyl O of Gly, D-Glu, and D-Ala formed coordination bonds with the Al atoms on the surface. Additionally, hydrogen bonds existed between the surface silanol groups and oxygen-containing groups of NAG, NAM and glycerol, as well as phosphate groups. The interaction induced the elongation of Si-O and Al-O bonds in the albite unit cell, resulting in a loosened framework structure and the subsequent release of Na⁺. Concurrently, the surface structure, wettability, and charge of albite were altered. Specifically, the hydroxyl and carbonyl groups of NAM preferentially interacted with the albite surface, serving as anchor points for the interaction of the remaining components of the CWMS.Conclusion This study clarifies the interaction between JT CWMS and albite, providing a theoretical basis for microbial promotion of silicate mineral decomposition.