SusChEM: Engineered protein-based biofilms as functional advanced materials

非技术性：哈佛大学材料研究部生物材料项目授予哈佛大学的SusCheM奖是一项广泛的努力的一部分，目的是为提取稀土金属和材料而“驯化”细菌生物膜。生物膜是生活在自我生成的生物聚合物基质中的细菌细胞群落。该项目旨在对一种非致病的实验室大肠杆菌菌株进行基因工程，以产生具有有益功能的这种生物聚合物基质的改变形式。具体地说，生物膜将被修饰在具有金属结合能力的蛋白质表面。这种修饰将允许生物膜选择性地与稀土元素结合。稀土对各种尖端技术至关重要，包括智能手机显示屏、电动汽车和风力涡轮机。因此，它们的可获得性对美国的技术创新和资源独立至关重要。尽管如此，由于缺乏环保和可持续的技术，世界上90%以上的稀土金属是在美国以外的地方开采和提取的。提出的工程化生物膜研究旨在开发更便宜、可持续、绿色和环境友好的技术来提取美国的稀土金属。与研究计划相结合的是一项密集的学生培训计划，该计划将纳入生物材料和生物工程领域的新教学举措，以及招收和指导几名研究生和本科生，重点是女性和代表性不足的少数族裔学生。本科生将通过在校园内建立的实习计划，接触STEM主题，重点是基因工程。与当地高中协调外展活动，以激发人们对STEM教育的兴趣也是该项目的一部分。技术：该SusCheM项目的总体目标是开发一个平台，用于基因工程细菌生物膜，可用作具有可编程、非自然功能的可扩展材料。凭借这一奖项，首席研究员将研究细菌分泌的生物膜中存在的蛋白质网状表面涂层的基因改造和特征。这种被称为“卷曲”的蛋白质表面涂层含有结构蛋白，这些结构蛋白在生物膜中自组装成一个由淀粉样纤维组成的胶囊网络。这项研究涉及将多肽基序与“卷曲”蛋白进行遗传融合，使融合的多肽位于生物膜中淀粉样纤维的表面。这些修饰的“Curli”蛋白将被研究结构和功能特性，重点是特定的金属结合能力。多肽修饰的生物膜将被生产出来，它们形成细胞外淀粉样蛋白网络的能力将被表征为多肽连接物长度的函数。将使用平板筛选策略来评估工程生物膜的组成和金属结合性能，并确定那些可以选择性和有效地浓缩稀土元素的生物膜。该系统还将集成在实验室规模的连续流动分离设备中，以评估其在工业相关模型中的潜力。最终，这项研究的结果将有助于利用可再生资源开发一系列基于生物膜的材料。这项研究将与跨学科指导计划相结合，在该计划中，研究生和本科生将接受分子生物学、材料科学和化学/生物工程等子领域的培训。

Nontechnical: This SusCheM award by the Biomaterials program in the Division of Materials Research to Harvard University is part of a broad effort to "domesticate" bacterial biofilms for the extraction of rare earth metals and materials. Biofilms are communities of bacterial cells living inside a self-generated biopolymer matrix. This project aims to genetic engineer a non-pathogenic laboratory strain of E. coli to produce altered forms of this biopolymer matrix that have beneficial functions. Specifically, biofilms will be modified the surfaces of proteins with metal binding capabilities. This modification will allow the biofilms to selectively bind to rare earth elements. Rare earths are essential for a variety of cutting edge technologies, including smartphone displays, electric vehicles, and wind turbines. As such, their availability is critical to technological innovation and resource independence in the United States. Despite this, more than 90% of the world's rare earth metals are mined and extracted outside United States because of the lack of environmental and sustainable technologies. The engineered biofilms research proposed aims to develop cheaper, sustainable, green and environment-friendly technologies to extract rare earth metals in USA. Integrated with the research plan will be an intensive student trainings program that will incorporate new teaching initiatives in the fields of biomaterials and bioengineering, and recruiting and mentorship of several graduate and undergraduate students with a focus on women and underrepresented minority students. Undergraduate students will be exposed to STEM topics with a focus on genetic engineering through established internship programs in the Campus. Coordination of outreach activities with local high schools to stimulate interest in STEM education is also part of this project.Technical: The overall goal of this SusCheM project is to develop a platform for genetically engineering bacterial biofilms that can serve as scalable materials with programmable, non-natural functions. With this award, the Principal Investigator will study the genetic modification and characterization of the proteinaceous mesh-like surface coating present in biofilms secreted by bacteria. This proteinaceous surface coating called 'curli' contains structural proteins, which self-assemble into an encapsulating network of amyloid fibers in the biofilm. This research involves genetic fusion of peptide motifs to the 'curli' proteins such that the fused peptides are on the surface of the amyloid fibers in the biofilm. These modified 'curli' proteins will be studied for structural and functional properties with a focus on specific metal binding capabilities. The peptide modified biofilms will be produced, and their ability to form extracellular amyloids networks will be characterized as a function of peptide linker length. A plate-based screening strategy will be used to evaluate the composition and metal binding properties of the engineered biofilms and identify those that can selectively and efficiently enrich rare earth elements. The system will also be integrated in a laboratory scale continuous flow separation apparatus to evaluate its potential in an industrially relevant model. Ultimately, the results of this investigation will facilitate the development of a wide range of biofilm-based materials using renewable sources. The research will be integrated with a cross-disciplinary mentoring plan in which graduate and undergraduate students will be trained in subfields of molecular biology, materials science, and chemical/biological engineering.