EAGER:Large-Scale Behavior and Collective Effects in Concentrated Bacterial Suspensions in Mucus

各向异性粘弹性介质中活性自推进颗粒的运动和自组织是当前交叉学科研究的热点。了解细菌和粘液之间的相互作用是开发更好的方法对抗病原体入侵粘膜表面的关键。细菌-粘液相互作用对于一类表现出粘弹性行为和长记忆效应的复杂流体来说是重要的，无论是生物的还是合成的。通过实验和理论建模的结合，PI将探索细菌-粘液相互作用的一个全新领域：在较高的细菌浓度下出现的集体效应是什么作用，以及悬浮介质的粘弹性和记忆如何控制新出现的集体模式。这项研究将刺激细菌-粘液相互作用的实验技术和预测数学工具的变革性变化，更广泛地说，在复杂的生物流体中的微泳者。这项工作有望引发对细菌和其他移动微生物如何在复杂的生物流体中游泳的革命性理解。它对预防许多细菌传播的疾病、治疗不孕不育以及开发更好的方法对抗病原体入侵粘膜表面具有多重意义。开放源码的计算算法将提供给广大的科学和工程界，并可以在支持GPU的台式计算机上运行。通过这项研究，PIS将为学生和博士后提供跨学科的培训和教育，他们将学习应用数学和计算物理的理论技术，以及生物物理和工程中使用的实验技术。将接待来自代表性不足群体的本科生，并启动公共推广计划。粘液是一种粘弹性凝胶，覆盖在暴露在外部环境中的动物器官束细胞和组织的表面。它是防止细菌和病毒等病原体入侵和侵占组织的前线保护。在这个项目中，PI将极大地扩展和加深我们对粘液中浓缩细菌悬浮液中大规模行为和集体效应的出现的知识。PI将探索粘液粘弹性、各向异性和长期记忆如何影响集体行为的性质及其对强制剪切流的反应。为了进一步加深理解，他们将把活性液晶的计算模型推广到有记忆的各向异性粘弹性线形介质的情况。这种实验和理论方法的协同将促进对失衡集体行为的理解。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Motility and self-organization of active self-propelled particles in anisotropic and viscoelastic media is an active area of interdisciplinary research. Understanding the interaction between bacteria and mucus is key to developing better ways to fight the pathogen invasion at mucosal surfaces. Bacteria-mucus interaction is important to a general class of complex fluids exhibiting viscoelastic behavior and long memory effects, both biological and synthetic. By a combination of experiments and theoretical modeling the PIs will explore a fundamentally new area of bacteria-mucus interaction: what is the role of collective effects appearing at higher bacterial concentrations and how the viscoelasticity and memory of the suspending medium control the emerging collective patterns. The research will stimulate the transformative changes in experimental techniques and predictive mathematical tools for bacteria-mucus interaction and, more generally, microswimmers in complex biological fluids. The work is expected to trigger transformative understanding of how the bacteria and other motile microorganisms swim in complex biological fluids. It has multiple implications for the prevention of many bacteria-born illnesses, treatment of infertility, and developing better ways to fight the pathogen invasion at mucosal surfaces. The open-source computational algorithms will be made available to the broad scientific and engineering communities and can be run on a GPU-enabled desktop computer. Through this research the PIs will provide interdisciplinary training and education of students and postdocs who will learn theoretical techniques in applied mathematics and computational physics, as well as experimental techniques employed in biological physics and engineering. Undergraduate students from underrepresented groups will be hosted and public outreach programs will be initiated. Mucus is a viscoelastic gel coating the surfaces of cells and tissues in animal organ tracts exposed to the external environment. It serves as frontline protection against invasion and colonization of tissues by pathogens such as bacteria and viruses. In this project the PIs will significantly expand and deepen our knowledge of the emergence of large-scale behavior and collective effects in concentrated bacterial suspensions in mucus. The PIs will explore how mucus viscoelasticity, anisotropy, and long-term memory affect the properties of collective behavior and its response to imposed shear flow. To further advance the understanding, they will extend the computational model of active liquid crystals to the case of the anisotropic viscoelastic nematogenic medium with memory. This synergy of experimental and theoretical approaches will advance understanding of out-of-equilibrium collective behavior.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.