Interactions of Biomolecules and Bacteria with Titanium at the Mineral Microbe Frontier

在这个由化学学部环境化学科学项目资助的项目中，天普大学的Ann Valentine教授正在研究生物分子和整个微生物是如何结合和溶解氧化钛表面的。钛是地球上最丰富的元素之一，但它在生物学中的作用，充其量是模糊的。钛氧化物是钛在环境中最常见的形式，但它们通常是惰性的。清除铁的生物分子开启了一种不受欢迎的活动：将大量钛离子释放到溶液中。这项研究揭示了钛在生物学中的作用，反过来，生物学是如何影响钛的环境化学的。这个项目的重点是清除铁的铁载体和细菌与二氧化钛表面的相互作用，以及这些相互作用的化学后果。“铁载体”介导的钛离子从二氧化钛的动员是定量表征。利用衰减全反射-傅里叶变换红外（ATR-FTIR）光谱以及显微等相关技术对溶解前后和溶解过程中的氧化物表面和材料性质进行了研究。利用橡胶红球菌GIN-1研究了微生物/氧化物和生物分子/氧化物的相互作用，这种细菌能与二氧化钛密切结合，并将钛结合到其生物量中。二氧化钛表面结合蛋白已被鉴定和表征，其丰度和性质与整个生物体现象相关。钛的摄取正在被量化和细胞内钛结合分子的分离。对红杜鹃GIN-1铁载体进行了分离和表征。研究活动与天普大学本科化学入门课程的教学计划相结合。环境生物无机化学是化学外展工作的特色。这项工作的广泛影响包括将有机分子锚定在二氧化钛表面的新策略带来的潜在技术效益，以及第一个天然钛-生物分子复合物和潜在的钛酶的鉴定。

In this project funded by the Environmental Chemical Sciences Program of the Chemistry Division, Professor Ann Valentine of Temple University is studying how biological molecules and whole microorganisms bind to and dissolve titanium oxide surfaces. Titanium is one of the most abundant elements on earth, but its role in biology is, at best, obscure. Titanium oxides are the most prevalent form of titanium in the environment, but they are normally very inert. Iron-scavenging biomolecules unlock an activity that is otherwise disfavored: the release of large quantities of titanium ions into solution. This research is revealing the role of titanium in biology and, conversely, how biology impacts the environmental chemistry of titanium.This project focuses on the interactions of iron-scavenging siderophores and bacteria with titanium dioxide surfaces, and on the chemical consequences of those interactions. The "siderophore"-mediated mobilization of titanium ions from titanium dioxide is being characterized quantitatively. The oxide surface and materials properties before, after, and during dissolution is being probed by using Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy as well as microscopy and related techniques. Microbe/oxide and biomolecule/oxide interactions are being studied by using the bacterium Rhodococcus ruber GIN-1, which adheres avidly to titanium dioxide and incorporates titanium into its biomass. Titanium dioxide surface binding proteins are being identified and characterized, and their abundance and properties correlated to whole-organism phenomena. Titanium uptake is being quantified and intracellular titanium binding molecules isolated. Rhodocuccus ruber GIN-1 siderophores are being isolated and characterized. Research activities are integrated with a program to improve teaching and learning in introductory undergraduate chemistry at Temple University. Environmental bioinorganic chemistry is featured in chemistry outreach efforts. The broader impacts of this work include potential technological benefits from new strategies for anchoring organic molecules to titanium dioxide surfaces, and from the identification of the first native titanium-biomolecule complex and potentially a titanium enzyme.