Unraveling the Constrained Cell Growth in Engineered Living Materials

Engineered living materials (ELMs) leverage the integrative advantages of materials science and synthetic biology for advanced functionalities. Predicting and controlling cellular behavior are essential for designing and building ELMs, requiring a fundamental understanding of the growth dynamics of encapsulated cells. Here, we interrogate the interference of constrained growth with the engineered functionalities and cellular physiology of cyanobacteria and unveil the dynamic interaction between cell growth and spatial confinements within photosynthetic ELMs. We observed that engineered cyanobacteria within ELMs exhibited compromised performances in growth, uptake of nonutilizable substrate, and synthesis of customized products, while ELMs could protect encapsulated cells from external stresses. Besides commonly accepted external influences, we identified abnormally high levels of reactive oxygen species and impaired oxygen photosynthesis inside the cells encapsulated in the ELMs. Finally, we illustrated the dynamics of cell growth within the confined spaces enveloped by the material matrices, forming clustered cell aggregates and compressed growth bubbles until the spatial limits. Our study provides a fundamental yet often overlooked connection between cellular behavior and spatial confinement, consolidating the foundation for advanced ELM innovations.