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Living systems have not only the exemplary capability to fabricate materials (e.g., wood, bone) under ambient conditions but they also consist of living cells that imbue them with properties like growth and self-regeneration. Like a seed that can grow into a sturdy living wood, can living cells alone serve as the primary building block to fabricate stiff materials? Here is reported the fabrication of stiff living materials (SLMs) produced entirely from microbial cells, without the incorporation of any structural biopolymers (e.g., cellulose, chitin, collagen) or biominerals (e.g., hydroxyapatite, calcium carbonate) that are known to impart stiffness to biological materials. Remarkably, SLMs are also lightweight, strong, and resistant to organic solvents and can self- regenerate. This living materials technology can serve as a powerful biomanu- facturing platform to design and develop advanced structural and cellular materials in a sustainable manner. 

Petrochemical-based plastics have not only contaminated all parts of the globe, but are also causing potentially irreversible damage to our ecosystem because of their non-biodegradability. As bioplastics are limited in number, there is an urgent need to design and develop more biodegradable alternatives to mitigate the plastic menace. In this regard, we report aquaplastic, a new class of microbial biofilm-based biodegradable bioplastic that is water-processable, robust, templatable and coatable. Here, Escherichia coli was genetically engineered to produce protein-based hydrogels, which are cast and dried under ambient conditions to produce aquaplastic, which can withstand strong acid/base and organic solvents. In addition, aquaplastic can be healed and welded to form three-dimensional architectures using water. The combination of straightforward microbial fabrication, water processability and biodegradability makes aquaplastic a unique material worthy of further exploration for packaging and coating applications. 

Abstract Bacterial cellulose (BC) has excellent material properties and can be produced sustainably through simple bacterial culture, but BC‐producing bacteria lack the extensive genetic toolkits of model organisms such asEscherichia coli(E. coli). Here, a simple approach is reported for producing highly programmable BC materials through incorporation of engineeredE. coli. The acetic acid bacteriumGluconacetobacter hanseniiis cocultured with engineeredE. coliin droplets of glucose‐rich media to produce robust cellulose capsules, which are then colonized by theE. coliupon transfer to selective lysogeny broth media. It is shown that the encapsulatedE. colican produce engineered protein nanofibers within the cellulose matrix, yielding hybrid capsules capable of sequestering specific biomolecules from the environment and enzymatic catalysis. Furthermore, capsules are produced which can alter their own bulk physical properties through enzyme‐induced biomineralization. This novel system uses a simple fabrication process, based on the autonomous activity of two bacteria, to significantly expand the functionality of BC‐based living materials.