Collaborative Research: Understanding Bacterial Flagellar Propulsion

像大肠杆菌和鼠伤寒沙门氏菌这样的细菌通过旋转它们的螺旋鞭毛在流体中游动。了解鞭毛细菌的游动机制是一个具有挑战性的课题，涉及生物，工程，数学和物理科学之间的相互作用。 尽管许多科学家研究了细菌游动，但实验和理论研究都表明，由于鞭毛在运动过程中的复杂几何形状，很难理解鞭毛的动态行为，并且仍然存在许多悬而未决的问题。 该项目将开发和验证这种细菌运动的改进数学模型。本项目的目标是：（1）建立详细的数学模型，并结合数值方法来理解细菌通过鞭毛的运动;（2）分析流体中细胞体产生的多个鞭毛之间复杂的流体动力学相互作用;（3）通过将结果与实验数据进行比较来验证模型;（4）使用这些模型进行预测，并通过进一步的实验进行验证。该项目还大量涉及广义浸入边界方法的自适应版本的开发，该方法将在生物流体动力学中找到许多应用，如超螺旋DNA动力学。新的数值算法将在IBAMR软件中免费在线分发。从这项关于自由游动细菌的研究中获得的结果可能会提供有关感染传播和生物膜形成的新信息，并可能有助于设计由鞭毛自行推进的纳米机器。

Bacteria such as Escherichia coli and Salmonella typhimurium swim through a fluid by rotating their helical flagella. Understanding the swimming mechanism of bacteria with flagella is a challenging subject that involves interactions between the biological, engineering, mathematical, and physical sciences. Although many scientists have studied bacterial swimming, experimental and theoretical studies have both shown that it is difficult to understand the dynamic behavior of the flagellum because of its complex geometry during locomotion, and many open questions remain. This project will develop and validate improved mathematical models for such bacterial motility. The goals of this project are to: (1) develop detailed mathematical models accompanied by the numerical schemes to understand bacterial motility by means of flagella; (2) analyze the complicated hydrodynamic interactions among multiple flagella arising from the cell body in fluids; (3) validate the models by comparing the results to experimental data; and (4) use these models to make predictions that will be verified by further experimentation. This project also heavily involves the development of an adaptive version of the generalized immersed boundary method which will find numerous applications in biological fluid dynamics such as supercoiling DNA dynamics. The new numerical algorithm will be freely distributed on-line within IBAMR software. The results obtained from this research on free swimming bacteria may provide new information about the spread of infections and biofilm formation, and may help to design nanomachines that are self-propelled by flagella.