Microbial Attachment to Minerals: Experimental Studies on Mineral-Driven Chemotaxis, & Role of Crystallography & Microtopography in Site-Specific, Oriented Cell Attachmen

为了评估和预测微生物在各种环境中对矿物溶解和沉淀等过程的影响，我们首先需要关于细胞发生在何处的信息。众所周知，环境中的微生物生物量是高度异质性的，并且细胞通常附着在表面而不是自由生活。然而，是什么控制着细胞的分布——实际上是它们附着在什么表面上——人们知之甚少。微生物对表面的附着已经被广泛研究，但很少在可以用来理解自然系统的背景下。迄今为止的研究主要是基于简化的模型，忽略了某些可能是决定细胞自然分布的关键因素。提出的研究重点是确定微生物机制和控制微生物附着在矿物表面的表面力。具体目标包括：1)确定微生物代谢在确定底物附着特异性中的重要性；2)确定晶体化学、晶体结构和表面微形貌（位阻效应）在附着中所起的作用。为了实现这些目标，将进行两条主要的实验路线。为了确定微生物代谢的作用，将对具有特定代谢能力的微生物进行附着试验，目的是定量确定趋化性在底物选择性中所起的作用。为了确定立体效应如何影响附着，实验将与理论计算相结合，考虑细胞类型、细胞壁厚度、细胞大小等因素。微生物细胞和矿物基质之间的特定表面力将通过原子力显微镜（AFM）进行量化。

In order to assess and predict the impact microorganisms have on processes such as mineral dissolution and precipitation over a wide range of environments, we need first information on where cells occur. It is well known that microbial biomass in the environment is highly heterogeneous, and that cells are generally found attached to surfaces rather than free living. Yet what controls cell distribution - in effect what surfaces they attach to - is poorly understood. Microbial attachment to surfaces has been widely studied but rarely in context that can be used to understand to natural systems. Studies to date have largely been based on simplified models that neglect certain factors that may be key in determining the natural distribution of cells.The proposed research focuses on determining the microbial mechanisms and surface forces that govern microbial attachment to mineral surfaces. Specific goals include: 1) determining the importance of microbial metabolism in determining substrate specificity for attachment, and 2) determining what role crystal chemistry, crystal structure, and surface microtopography (steric effects) play in attachment. To achieve these goals, two primary lines of experiments will be conducted. To determine the role of microbial metabolism, attachment assays will be conducted with microorganisms selected for specific metabolic capabilities, with the aim of quantitatively determining the role chemotaxis plays in substrate selectivity. To determine how steric effects impact attachment, experiments will be conducted in concert with theoretical calculations that account for factors such as cell type, cell wall thickness, cell size, etc. Specific surface forces between microbial cells and mineral substrata will be quantified by Atomic Force Microscopy (AFM).