Active Smectic Hydrodynamic Models of Colony Growth.

菌落生长的主动近晶流体动力学模型。

• 批准号: 2295765
• 金额: --
• 依托单位: Loughborough University
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2019
• 资助国家: 英国
• 起止时间: 2019 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2295765
• 关键词: Active; Smectic; Hydrodynamic; Models; Colony

Complex spatial patterns emerge in bacterial communities in response to internal and external pressures. The resulting structure is instrumental in everything from interspecies competition to acquisition of antibacterial resistance. While current massive sequencing efforts yield vast data about community composition, they fail to provide positional information, despite its integral role in bacterial communities. This project will study the spatiotemporal patterning of growing communities by resolving the essential physical principles that drive shape and dynamics on a microcolony-wide scale. Understanding community-wide self-organization within host environments requires predictive mathematical theories that balance conceptual simplicity and polymicrobial complexity. While recent theories for the collective dynamics of cell motion have found some success by employing continuum active nematic liquid crystal models for colony dynamics, there are clear insurmountable shortcomings to reproducing the multiplex internal organization of real microbial colonies. In particular, these nematic models limit the internal ordering of baciliforms to orientational alignment. However, brightfield fluorescence and microscopy images of microcolonies of Pseudomonas aeruginosa for example show internal structuring, including rafts (small clusters of coherent motile baciliforms groupings), multilayers (distinct tiers of vertical strata), interfacial counter-sliding (single lane of baciliforms at the very edge of the colony moving in the opposite direction to the bulk), and in-plane smectic layering (stacked in well-defined planes parallel to the surface). Each of these observed phenomena involves layer ordering of baciliforms, which fundamentally cannot be accounted for by previous nematohydrodynamic theories.Thus, this project proposes that a novel theory for active smectic fluids will allow us to understand active turbulence in baciliform colonies, including intrinsic length scales of in-plane smectic layering and associated collective dynamics. Jack Paget will extend 2D active smectic theory to account for both the in-plane smectic layering and also the multilayer colonies. By implementing a phase field hybrid model to simulate colony/fluid interfaces, he reproduce and understand counter-flowing interfacial monolayers and active stresses on colony interfaces. Our theoretical framework will tightly couple growth to orienational order. Future work will be to hybridize smectic code with reaction-diffusion equations, to produce chemotactic communication between competing colonies and within each colony.

细菌群落中出现了复杂的空间格局，以响应内部和外部的压力。由此产生的结构在从物种间竞争到获得抗菌素耐药性的一切过程中都起到了重要作用。虽然目前的大规模测序工作产生了关于群落组成的大量数据，但它们未能提供位置信息，尽管它在细菌群落中发挥着不可或缺的作用。这个项目将通过解决在微群落范围内驱动形状和动态的基本物理原理来研究不断增长的群落的时空模式。要理解宿主环境中的社区范围的自组织，需要有预测性的数学理论来平衡概念的简单性和多微生物的复杂性。虽然最近关于细胞运动的集体动力学的理论已经通过使用连续统活动向列液晶模型来研究菌落动力学而取得了一些成功，但在再现真实微生物菌落的多重内部组织方面仍存在明显的不可逾越的缺点。特别是，这些向列型模型将杆状结构的内部排序限制为定向排列。然而，例如铜绿假单胞菌微菌落的明亮荧光和显微镜图像显示了内部结构，包括木筏(一小群连贯的可移动的杆菌群)、多层(不同的垂直地层)、界面逆滑动(菌落边缘的单线杆菌沿与主体相反的方向移动)以及面内近晶分层(堆积在与表面平行的明确平面上)。每一种观察到的现象都涉及杆状结构的层序，这是以前的线虫流体动力学理论所不能解释的。因此，这个项目提出了一种新的关于活跃近晶流体的理论将使我们能够理解杆状群体中的活跃湍流，包括面内近晶层化的内在长度尺度和相关的集体动力学。Jack Paget将扩展2D活性近晶理论以解释面内近晶分层和多层团簇。通过实施相场混合模型来模拟群体/流体界面，他再现并理解了逆流界面单分子层和群体界面上的主动应力。我们的理论框架将把增长与方向秩序紧密地联系在一起。未来的工作将是将近晶密码与反应扩散方程混合，在竞争的蜂群之间和每个蜂群内产生趋化通讯。