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

各向异性粘弹性介质中主动自走粒子的运动和自组织是一个活跃的跨学科研究领域。了解细菌和粘液之间的相互作用是开发更好的方法来对抗粘膜表面病原体入侵的关键。细菌-黏液的相互作用对一类具有粘弹性行为和长记忆效应的复杂流体非常重要，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：在较高细菌浓度下出现的集体效应的作用是什么，悬浮介质的粘弹性和记忆如何控制新出现的集体模式。这项研究将刺激实验技术和预测数学工具的革命性变化，用于细菌-粘液相互作用，更广泛地说，用于复杂生物流体中的微游泳者。这项工作有望引发对细菌和其他活动微生物如何在复杂的生物流体中游动的革命性理解。它对预防许多细菌传播的疾病，治疗不孕症，以及开发更好的方法来对抗粘膜表面的病原体入侵具有多重意义。开源计算算法将提供给广泛的科学和工程社区，并可以在支持gpu的台式计算机上运行。通过这项研究，pi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。来自代表性不足群体的本科生将被接待，并将启动公共外展项目。黏液是一种粘弹性凝胶，覆盖在暴露于外界环境的动物器官束的细胞和组织表面。它是防止细菌和病毒等病原体入侵和定植组织的第一线保护。在这个项目中，pi将显著扩展和加深我们对黏液中浓缩细菌悬浮液中大规模行为和集体效应的认识。pi将探讨黏液的粘弹性、各向异性和长期记忆如何影响集体行为的性质及其对施加剪切流的响应。为了进一步加深理解，他们将主动液晶的计算模型扩展到具有记忆的各向异性粘弹性致线虫介质的情况。这种实验和理论方法的协同作用将促进对非平衡集体行为的理解。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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.