Bacterially grown living materials with resistant and on-demand functionality.

Inspired by naturally occurring biomaterials, autonomously grown engineered living materials (ELMs) feature cell-driven growth and programmable biological functions. However, the "livingness" of cells poses a short life span and low tolerance to harsh conditions, limiting the practical use of such materials. Here, we developed materials with programmable and dormant functionalities, grown from a mixture of Komagataeibacter rhaeticus and Bacillus endospores under engineered medium conditions. K. rhaeticus produces the bacterial cellulose (BC) matrix that integrates Bacillus spores within, whereas the confined spores keep dormant and are resistant to harsh conditions in the environment. Bacillus spores can germinate and confer desired functions to the materials. Modulating the binding affinity of spores to the BC matrix with genetic engineering can improve cell loading and therefore enhance the material functionality. These materials can serve as a versatile on-demand platform for applications as biosensors, biocatalytic materials, and in situ transformation of mechanically robust cellulose-based composites.