Living active collectives have evolved with remarkable self-patterning capabilities to adapt to the physical and biological constraints crucial for their growth and survival. However, the intricate process by which complex multicellular patterns emerge from a single founder cell remains elusive. In this study, we utilize an agent-based model, validated through single-cell microscopy imaging, to track the three-dimensional (3D) morphodynamics of cells within growing bacterial biofilms encased by agarose gels. The confined growth conditions give rise to a spatiotemporally heterogeneous stress landscape within the biofilm. In the core of the biofilm, where high hydrostatic and low shear stresses prevail, cell packing appears disordered. In contrast, near the gel–cell interface, a state of high shear stress and low hydrostatic stress emerges, driving nematic ordering, albeit with a time delay inherent to shear stress relaxation. Strikingly, we observe a robust spatiotemporal correlation between stress anisotropy and nematic ordering within these confined biofilms. This correlation suggests a mechanism whereby stress anisotropy plays a pivotal role in governing the spatial organization of cells. The reciprocity between stress anisotropy and cell ordering in confined biofilms opens new avenues for innovative 3D mechanically guided patterning techniques for living active collectives, which hold significant promise for a wide array of environmental and biomedical applications.

中文翻译：

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基于代理的生物膜生长中应力各向异性驱动的向列排序建模

活跃的集体已经进化出卓越的自我模式能力，以适应对其成长和生存至关重要的物理和生物限制。然而，复杂的多细胞模式从单个创始细胞中产生的复杂过程仍然难以捉摸。在这项研究中，我们利用通过单细胞显微镜成像验证的基于代理的模型来跟踪琼脂糖凝胶包裹的生长细菌生物膜内细胞的三维 (3D) 形态动力学。受限的生长条件导致生物膜内产生时空异质的应力景观。在生物膜的核心，高静水压力和低剪切应力占主导地位，细胞堆积显得无序。相反，在凝胶-细胞界面附近，出现高剪切应力和低静水应力的状态，驱动向列有序，尽管剪切应力松弛固有的时间延迟。引人注目的是，我们观察到这些受限生物膜内的应力各向异性和向列有序之间存在强大的时空相关性。这种相关性表明应力各向异性在控制细胞的空间组织中发挥关键作用的机制。受限生物膜中应力各向异性和细胞排序之间的相互作用为活体活跃集体的创新 3D 机械引导图案化技术开辟了新途径，这为广泛的环境和生物医学应用带来了重大前景。