(615e) Fungal Hyphae As Natural Scaffolds for Enhancing Biocement Properties

Engineered Living Materials (ELMs) offer a sustainable alternative to traditional concrete, which contributes approximately 8% of global CO₂ emissions. Biocement, an ELM mineralized by Microbially Induced Calcite Precipitation (MICP), can bind aggregates at mesophilic temperatures with minimal carbon emissions. It also offers self-healing potential, making it a promising material for infrastructure. However, mechanical strength, microbial viability, and media cost remain key challenges for biocement.

Our research uses novel cocultures of filamentous fungi and bacteria (Sporosarcina pasteurii) to enhance biocement strength, to improve microbial survival, and to reduce media costs. Both organisms are ureolytic, driving MICP through urea hydrolysis, increasing local pH, and facilitating calcium carbonate precipitation. Negatively charged bacterial cells act as nucleation sites, attracting calcium ions, while fungal hyphae provide a high-surface-area scaffold that promotes extended mineral bridging. This dual mechanism balances fine-grained mineralization with extended calcium carbonate bridges. Biocement columns were generated by alternating microbial and biocementation solutions. Unconfined compressive strength (UCS) was measured at multiple locations using a pocket penetrometer. Columns pre-seeded with fungi and later treated with S. pasteurii achieved the highest UCS, outperforming bacteria-only samples. Ongoing work includes scale-up testing of biocement structures (2-inch cubes) and detailed spatial chemical analyses.

Fungal hyphae are proposed to act as biologically regenerative scaffolds, improving bacterial survival, and enhancing the self-healing potential of biocement. We hypothesize that optimized fungal-bacterial cocultures will improve mineral uniformity, microbial longevity, and long-term repair performance compared to bacteria-only MICP. This research will also quantify cost reductions based on utilizing fungi's ability to grow on low-cost substrates. This work aims to advance biocement as a durable, self-healing, and sustainable construction material by leveraging the synergistic properties of fungal-bacterial systems.