Bacterial synthetic multicellular systems are promising platforms for engineered living materials (ELMs) for medical, biosynthesis, environmental, and smart materials applications. Recent advancements in genetically encoded adhesion toolkits have enabled precise manipulation of cell-cell adhesion and the design and patterning of self-assembled multicellular materials. However, in contrast to gene regulation in synthetic biology, the characterization and control of synthetic adhesins remains limited. Here, we demonstrate the quantitative characterization of a bacterial synthetic adhesion toolbox through various biophysical methods. We determine key parameters, including number of adhesins per cell, in-membrane diffusion constant, production and decay rates, and bond-breaking force between adhesins. With these parameters, we demonstrate the bottom-up prediction and quantitative tuning of macroscopic ELM properties (tensile strength) and, furthermore, that cells inside ELMs are connected only by a small fraction of available adhesins. These results enable the rational engineering, characterization, and modeling of other synthetic and natural adhesins and multicellular consortia.

细菌合成多细胞系统是用于医疗、生物合成、环境和智能材料应用的工程活性材料（ELM）的有前景的平台。基因编码粘附工具包的最新进展使得能够精确操纵细胞间粘附以及自组装多细胞材料的设计和图案化。然而，与合成生物学中的基因调控相比，合成粘附素的表征和控制仍然有限。在这里，我们通过各种生物物理方法展示了细菌合成粘附工具箱的定量表征。我们确定关键参数，包括每个细胞的粘附素数量、膜内扩散常数、产生率和衰减率以及粘附素之间的键断裂力。通过这些参数，我们展示了宏观 ELM 特性（拉伸强度）的自下而上预测和定量调整，此外，ELM 内部的细胞仅通过一小部分可用的粘附素连接。这些结果使得其他合成和天然粘附素以及多细胞联合体的合理工程、表征和建模成为可能。