Mycelium as a scaffold for biomineralized engineered living materials

Summary Engineered living materials (ELMs) are garnering considerable attention as a promising alternative to traditional building materials because of their potentially lower carbon footprint and additional functionalities conferred by living cells. However, biomineralized ELMs designed for load-bearing purposes are limited in their current design and usage for several reasons, including (1) low microbial viability and (2) limited control of specimen internal microarchitecture. We created ‘third generation’ biomineralized ELMs from fungal mycelium scaffolds that were mineralized either by the fungus itself or by ureolytic bacteria. Both self-mineralized (i.e. fungally-mineralized) and bacterially-mineralized scaffolds retained high microbial viability for at least four weeks in room temperature or accelerated dehydration storage conditions, without the addition of protectants against desiccation. The microscale modulus of calcium carbonate varied with the different biomineralized scaffold conditions, and moduli were largest and stiffest for bacterial biomineralization of fungal mycelium. As an example of how mycelium scaffolds can enable the design of complex internal geometries of biomineralized materials, osteonal-bone mimetic architectures were patterned from mycelium and mineralized using ureolytic bacteria. These results demonstrate the potential for mycelium scaffolds to enable new frontiers in the design of biomineralized ELMs with improved viability and structural complexity. Progress and Potential Biomineralized engineered living materials (ELMs) offer new approaches for increasing the sustainability of building materials and processes. However, the design and usage of biomineralized ELMs is constrained by several important limitations, including low microbial viability and limited ability to control internal microarchitecture. Fungal mycelium scaffolds, biomineralized by either fungi or bacteria, achieve much higher viability of ureolytic microorganisms than what has been reported for biomineralized ELMs. Further, mycelium scaffolds permit the manufacturing of complex architectures, such as inspired by the structure of osteonal bone. Mycelium scaffolds have the potential to enable new frontiers in the design and use of biomineralized ELMs. Graphical Abstract