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

由于人类和动物感染、产品污染和膜生物污染，Ardekani生物膜每年给美国造成数十亿美元的损失。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加强石油回收和碳封存。尽管生物膜具有广泛的影响，但最终导致生物膜流光形成的细菌聚集的潜在流体动力学目前尚不清楚。智力价值：细菌产生的胞外聚合物的特性在生物膜的形成中起着重要作用，这些聚合物是由大分子在液体中形成的丝状网络组成。为了了解生物膜的形成和生长，必须研究细菌在流存在下与胞外聚合物相互作用时在生态相关时空尺度上的聚集动力学。到目前为止，这是一个在很大程度上没有得到回应的挑战。这项拟议的研究将使用最先进的三维计算流体力学和实验技术来改变我们对细菌聚集的理解，这些聚集是由于流场、细菌形状、细菌运动和胞外聚合物的流变性造成的。文献表明，大小从微米到厘米的刚性颗粒在不同的粘弹性流体中强韧地聚集在一起。这项拟议的研究调查了一种假设，即粘弹性流体中的移动微生物受到强大的流体动力力，导致它们聚集在表面和/或彼此之间。关于细菌在这种复杂流体中流动时聚集的基础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：这项研究的影响延伸到重要的生物学、环境和海洋学应用。了解细菌聚集和生物被膜的形成对人类健康和环境控制至关重要。此外，使用计算流体动力学系统地研究细菌之间的相互作用，同时捕获其在复杂流体中的详细3D响应，对于正确预测病原体在粘膜组织和肠道中的未来定植状态至关重要。拟议的活动将大大促进对下一代科学家和工程师的跨学科培训。这笔赠款将支持培训两名研究生，帮助他们在国际和平研究所的实验室开发最先进的工具。将开发一门新的研究生课程，将这项研究纳入研究生教育。这一跨学科研究将被用作吸引妇女和代表性不足的少数群体等不同群体的平台。PI将领导与莱利高中南本德(印第安纳州)社区学校公司的工程和技术磁铁计划的工程教育合作伙伴关系，该计划的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。这项工作将包括为学生提供的动手实验和项目，目的是加强工程分析和设计的基本原理。通过利用已建立的衔接关系，来自全女子圣玛丽学院和两所历史悠久的黑人学院的女性和代表不足的少数族裔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.