CAREER:Fluid Dynamics of bacterial aggregation and formation of biofilm streamers

[150348]由于人类和动物感染、产品污染和膜的生物污染，ardekanibiofilm每年花费美国数十亿美元。除了对地下水中的污染物进行生物修复外，深层地下生物膜还可用于提高石油采收率和碳固存。尽管生物膜具有广泛的意义，但最终导致生物膜流线形成的细菌聚集的潜在流体动力学目前尚不清楚。智力优势：细菌产生的细胞外聚合物质的特性在生物膜的形成中起着重要的作用，这些物质由包围在流体中的大分子的丝状网络组成。为了了解生物膜的形成和生长，必须研究细菌在与细胞外聚合物相互作用的同时，在生态相关的时空尺度上，在水流存在下的聚集动力学。这是一个迄今为止基本上没有答案的挑战。该研究将采用最先进的三维计算流体动力学和实验技术来改变我们对细菌聚集的理解，因为流场、细菌形状、细菌运动和细胞外聚合物的流变性能。文献表明，从微米到厘米大小的刚性颗粒在粘弹性流体的不同流动中牢固地聚集。提出的研究调查了一种假设，即粘弹性流体中的活动微生物受到强大的水动力，导致它们聚集到表面和/或彼此聚集。在如此复杂的流体中，细菌聚集的基本知识可以改变我们对这些微生物过程的理解，并提高控制生物膜形成的能力。更广泛的影响：本研究的意义延伸到重要的生物、环境和海洋学应用。了解细菌聚集和生物膜的形成对人类健康和环境控制至关重要。此外，利用计算流体动力学系统地研究细菌相互作用的能力，同时捕获其在复杂流体中的详细3D响应，对于正确预测粘膜组织和粘膜束中病原体定植的未来状态至关重要。拟议的活动将大大有助于下一代科学家和工程师的跨学科培训。这笔拨款将用于培训两名研究生，以促进PI实验室中最先进工具的开发。将开设一门新的研究生课程，使研究与研究生教育相结合。这项跨学科研究将被用作吸引不同群体的平台，如妇女和代表性不足的少数民族。PI将与南本德（印第安纳州）社区学校公司莱利高中的工程和技术磁石项目合作，领导一个工程教育合作伙伴关系，重点是通过控制大肠杆菌水平来恢复当地小溪的水生生态系统。这项工作将包括学生的动手实验和项目，目的是加强工程分析和设计的基本原理。通过利用既定的衔接关系，来自全女子圣玛丽学院和两所传统黑人学院的女性和代表性不足的少数民族本科生将接受拟议研究的实验和数学方面的培训。

1150348ArdekaniBiofilms cost the U.S. billions of dollars every year due to human and animal infections, product contamination, and biofouling of membranes. Deep subsurface biofilms can be used for enhanced oil recovery and carbon sequestration in addition to bioremediation of contaminants in groundwater. Despite widespread implications of biofilms, the underlying hydrodynamics of bacterial aggregation that eventually leads to formation of biofilm streamers are currently unknown. Intellectual Merit: Properties of bacteria-produced extracellular polymeric substances consisting of a filamentous network of macromolecules surrounded in a fluid play an important role in biofilm formation. In order to understand biofilm formation and growth, the dynamics of bacterial aggregation at ecologically relevant spatiotemporal scales in the presence of flow while interacting with extracellular polymeric substances must be studied. This is a challenge largely unanswered to date. The proposed research will employ state-of-the-art three-dimensional computational fluid dynamics and experimental techniques to transform our understanding of bacterial aggregation due to flow field, bacteria shape, bacteria motility and rheological properties of extracellular polymer. The literature shows that rigid particles ranging in sizes from microns to centimeters robustly aggregate in different flows of viscoelastic fluids. The proposed research investigates a hypothesis that motile microorganisms in viscoelastic fluids undergo strong hydrodynamic forces that result in their aggregation to the surfaces and/or each other. The fundamental knowledge about the aggregation of bacteria in the presence of flow in such complex fluids can transform our understanding of these microbial processes and advance the ability to control biofilm formation. Broader Impact: The implications of this research extend to important biological, environmental, and oceanographic applications. Understanding of bacterial aggregation and formation of biofilms is crucial for human health and environmental control. Additionally, the ability to systematically investigate the interaction of bacteria using computational fluid dynamics, while capturing its detailed 3D response in complex fluids, is essential for correctly predicting the future state of the pathogen colonization in mucosal tissues and tracts. The proposed activity will significantly contribute to interdisciplinary training of the next generation of scientists and engineers. This grant will provide support for training of two graduate students fostering the development of state-of-the-art tools in the PI's laboratory. A new graduate course will be developed to integrate the research into graduate education. This interdisciplinary research will be used as a platform to attract diverse groups such as women and underrepresented minorities. The PI will lead an engineering education partnership with the Engineering and Technology Magnet Program for the South Bend (Indiana) Community School Corporation at Riley High School that focuses on restoring an aquatic ecosystem of a local creek by controlling Escherichia coli levels. The work will include hands-on experiments and projects for the students with the purpose of reinforcing basic principles of engineering analysis and design. By taking advantage of established articulation relationships, female and underrepresented minority undergraduate students from the all women's Saint Mary's and two Historically Black Colleges will be trained in experimental and mathematical aspects of the proposed research.