CAREER: Microorganisms swimming around microstructural heterogeneity

1252182Fu拟议工作的目标是从根本上了解移动微生物，如细菌，如何能够在复杂的生物环境中移动，例如身体组织或粘液，这些环境通常具有与微生物类似大小的微观结构特征。为了适当地研究这些微结构特征对游泳微生物的影响，将采用能够计算复杂几何形状的流动的数值计算。这些计算还将能够研究微结构和游泳微生物的灵活性，以及这种灵活性对游泳的影响。过去，大多数关于复杂环境中游泳行为的理论研究都只是从平均意义上处理微观结构，这些研究无法确定是什么环境特性控制了游泳行为。预计将微观结构明确地视为移动对象将使人们深入了解哪些特征促进或阻碍了这些环境中的移动。通过数值计算得到的结果将揭示微结构对游泳的影响的物理机制，并与没有明确考虑微结构的研究结果进行比较。微生物在微结构环境中的运动和推进影响着感染、保健和生态。例如，粘液的微观结构可以作为感染的屏障；这项研究可能会导致改变微观结构以阻止感染的方法。需要了解组织渗透，以设计能够精确地将药物输送到靶组织(如癌症肿瘤)的微型机器人，避免对其他组织的副作用。在生态学上，海洋生物的分泌物可以形成一个微结构网络；了解这个网络对游泳微生物的影响可能会改变对微生物觅食效率的估计，从而影响碳循环速率，从而影响全球气候。在环境方面，可以阻止细菌在多孔土壤中的扩散，以防止水污染，或加强细菌在土壤中的扩散，以促进污染物的生物修复。最后，这项拟议的工作还包含一个旨在创建“像微生物一样移动”的教育组成部分，这是一种对微尺度微生物运动的力反馈模拟。它将通过提供微生物如何游泳的动手演示，为公众和K-12学生带来拟议的研究，并解释微生物运动给日常生活带来的后果。

1252182FuThe goal of the proposed work is to obtain a fundamental understanding of how motile microorganisms, such as bacteria, are able to move through complex biological environments, such as bodily tissues or mucus, which often have microstructural features of similar size as the microorganisms. To properly study the effect of these microstructural features on swimming microorganisms, numerical computations capable of calculating the flows around complex geometries will be employed. These computations will also be able to study the flexibility of the microstructures and the swimming microorganisms and the effects of this flexibility on swimming. In the past, most theoretical investigations into swimming in such complex environments have only treated the microstructure in an average sense; these studies have not been able to determine what environmental properties control swimming behavior. It is expected that treating the microstructure explicitly as moving objects will give insight into what features promote or hinder movement through these environments. The results obtained through the numerical computations will expose the physical mechanisms of microstructural influence on swimming and be compared to results from investigations that do not treat the microstructure explicitly. Microorganism locomotion and propulsion in environments with microstructure affects infection, healthcare, and ecology. As examples, the microstructure of mucus can act as a barrier in infection; the research may lead to ways to alter the microstructure to hinder infection. Understanding tissue penetration is needed to design microrobots capable of precise delivery of drugs to targeted tissues such as cancer tumors, avoiding side effects in other tissues. Ecologically, the secretions of marine organisms can form a microstructural network; understanding the effects of this network on swimming microorganisms may alter estimates of microbial foraging efficiency, which affects carbon recycling rates and hence the global climate. Environmentally, bacterial dispersion in porous soils can be hindered to prevent water contamination or enhanced to promote bioremediation of pollutants. Finally, the proposed work also contains an educational component which aims to create "Move Like a Microbe," a force-feedback simulation of microscale microbial locomotion. It will bring the proposed research to life for the public and K-12 students by providing a hands-on demonstration of how microorganisms are able to swim, and explain the consequences of microbial locomotion to everyday life.