The dynamical extracellular matrix of bacterial colonies

细菌4型皮利（T4 P）是一种动态的胞外聚合物，对附着宿主细胞、运动性、生物膜形成和水平基因转移至关重要。以前，我们和其他人已经表明，它们的动力学和结合特性决定了淋病奈瑟菌（一种广泛传播的人类病原体）形成的菌落的物理特性。然而，很少有人知道他们的作用，在成熟的生物膜，以及他们如何与其他成分的细胞外基质（ECM）。在这里，我们将通过使用共聚焦成像，定量图像分析，激光镊子和分子生物学的组合来解决这一知识差距。我们将检验淋球菌ECM的机械性质是通过使殖民地稳定的动态T4 P和使殖民地稳定的静态细胞外DNA（eDNA）纤维之间的相互作用来调节的假设。首先，我们将独立地表征个体T4P的动态和三维淋球菌菌落内eDNA网络的形成。随后，我们将专注于它们在单细胞水平上的相互作用，并将结果与集落的结构，机械性能和稳定性联系起来。另一个主要目标是找出外部压力如何影响ECM的形成，反之亦然，基质如何保护细菌免受外部压力的影响。从长远来看，我们的目标是了解ECM如何重塑。我们计划生成具有设计特性的DNA凝胶，并研究这些特性如何影响合成基质的菌落生长和重塑。生物膜的物理性质对于适应变化的环境、增殖和胁迫耐受是重要的。因此，了解ECM如何调节这些特性至关重要。

Bacterial type 4 pili (T4P) are dynamical extracellular polymers that are essential for attachment host cells, motility, biofilm formation, and horizontal gene transfer. Previously, we and others have shown that their dynamics and binding properties govern the physical properties of colonies formed by Neisseria gonorrhoeae, a wide-spread human pathogen. However, little is known about their role during the maturation of biofilms and how they interact with other components of the extracellular matrix (ECM). Here, we will address this gap of knowledge by using a combination of confocal imaging, quantitative image analysis, laser tweezers, and molecular biology. We will test the hypothesis that the mechanical properties of the gonococcal ECM are adjusted by the interplay between dynamic T4P that fluidize the colony and static extracellular DNA (eDNA) fibres that stabilize the colony. First, we will independently characterize the dynamics of individual T4P and the formation of the eDNA network within three-dimensional gonococcal colonies. Subsequently, we will focus on their interaction at the single cell level and link the results to structure, mechanical properties, and stability of colonies. Another major aim will be to find out how external stresses affect ECM formation and, vice versa, how the matrix protects bacteria from external stresses. In the longer term, we aim at understanding how the ECM is remodeled. We plan on generating DNA gels with designed properties and investigate how these properties affect colony growth and remodelling of the synthetic matrix. The physical properties of biofilms are important for adaptation to changing environment, proliferation, and stress tolerance. Thus, it is crucial to understand how the ECM adjusts these properties.