Shape, wobble, and roll: adaptation of bacterial morphology to mechanical environments

细菌具有一致的大小和形状，这与它们生活环境的性质有关。球菌(球形)和杆菌(杆状)通常以丛生形式存在于土壤和哺乳动物的胃肠道中，而螺旋形细菌以其在密集介质中高效移动而闻名。这项工作的目的是阐明形状和大小如何决定细菌菌株对具有特定流变性的环境的适应性。这项工作由一台自动跟踪显微镜推动，该显微镜可以在3D中解析自由生活微生物的形状和运动。该项目将采用一种纯粹的机械方法来检查细菌形态在多大程度上是细胞适合性和毒力的指标。这项研究还旨在为机器人微型游泳者的设计提供指导，这些游泳者需要在复杂的流体介质中高效移动，以便及时输送药物或杀死病原体细胞。自动化显微镜的创新将有助于当地一所高中的互动教育项目，高中生将在那里学习如何使用3D打印机设计和优化实验工具。该项目将开发一个框架，将选择性细菌形态映射到生物栖息地的特定流变学属性。这项拟议的研究侧重于回答以下问题：微生物的细胞体如何有助于其游泳运动；不同的细胞形状如何产生显著的流变效应；以及这些环境效应是否可以被用来操纵细胞形状。单个细胞的形态及其三维运动将在自动跟踪显微镜下测量。PI将使用通过光刻制造的微流控设备为每个单独的细菌设计和创建流变学特征的梯度。结合跟踪显微镜，PI将研究周围介质的非牛顿特征对单个细胞运动的直接影响。PI还将创建微流控装置，以引入与时间相关的“选择性”压力，并旨在分离流体环境所偏好的表型。这种装置可以用来直接控制活的生物系统的表型表达，并将阐明表型变化如何使同一物种适应不同的生活环境。最终，这项工作的目的是创造新的方法，通过其流体环境的流体动力学特性来控制微生物的活动和功能。它还将指导未来医疗和工业应用的微型机器人的设计。

Bacteria have consistent sizes and shapes that are linked to the nature of their living environments. Cocci (with spherical shapes) and bacilli (with rod-like shapes) are generally found as clusters in soil and mammalian gastrointestinal tract, while spiral-shaped bacteria are known for their ability to move efficiently through dense media. The aim of this work is to elucidate how shape and size determine the adaptation of a bacterial strain to an environment with specified rheological properties. This work is facilitated by an automated tracking microscope that resolves the shape and motion of free-living microorganisms in 3D. The project will pursue a purely mechanical approach in examining the extent to which bacterial morphology is an indicator of cell fitness and virulence. This study also aims to be a guide to the design of robotic micro-scale swimmers that need to move efficiently through complex fluid media in order to deliver drugs or kill pathogenic cells in a timely manner. The innovation of the automated microscope will contribute to an interactive educational program at a local high school where high school students will be taught how to use a 3D printer to design and optimize experimental implements. This project will develop a framework that maps the selective bacterial morphology to the specific rheological properties of the living habitats. The proposed study focuses on answering the following questions: how the cell body of a microorganism contributes to its swimming motility; how different cell shapes produce marked rheological effects; and whether these environmental effects can be utilized to manipulate cell shapes. The morphology of an individual cell and its three-dimensional movements will be measured under an automated tracking microscope. The PI will design and create gradients of rheological features for each individual bacterium using microfluidic devices fabricated through photolithography. Combined with the tracking microscopy, the PI will study the direct impact of non-Newtonian features of the surrounding media on the motion of individual cells. The PI will also create microfluidic devices to introduce temporal-dependent "selective" pressures, and aim to isolate phenotypes preferred by the fluid environment. Such devices can be used to directly control the phenotypic expressions of live biological systems and will shed light on how phenotype variations allow the same species to adapt to various living habitats. Ultimately, this work aims at creating new approaches for controlling the activities and functions of microorganisms through the hydrodynamic properties of its fluid environment. It will also guide future design of micro-scale robots for medical and industrial applications.