Mycelium as a scaffold for biomineralized engineered living materials

<h2>Summary</h2> Engineered living materials (ELMs) are gaining attention because of their potential for sustainability and living properties, including self-healing, photosynthesis, and environmental responsiveness. While most ELMs are non-structural, biomineralized ELMs can be structural, offering reduced environmental impact compared to concrete while also offering living functionalities. However, challenges such as low microbial viability and a lack of complex internal structure have hindered the application of existing biomineralized ELMs. We created biomineralized ELMs using mycelium scaffolds, from <i>Neurospora crassa</i>, that were mineralized either by the fungus itself or by the bacterium <i>Sporosarcina pasteurii</i>. Self- and bacterially mineralized scaffolds retained microbial viability for at least 4 weeks when stored at 30°C. Biomineralization efficiency and mineral stiffness were greatest for bacterially mineralized scaffolds. To showcase their potential, mineralized mycelium scaffolds with internal geometries mimetic of cortical bone were fabricated. These results demonstrate how mycelium scaffolds can facilitate the production of biomineralized ELMs with greater viability and structural complexity.