In a new study, scientists have developed a living building material using fungal mycelium that can mineralize itself or be mineralized by bacteria, offering a potentially self-healing, sustainable alternative to concrete.
Study: Mycelium as a scaffold for biomineralized engineered living materials. Image Credit: luchschenF/Shutterstock.com
A recent study published in Cell Reports Physical Science explores a novel approach to sustainable construction materials. Researchers proposed a bio-based building material derived from the root-like mycelium of the fungus Neurospora crassa (N. crassa), which can be mineralized either by the fungus itself or by the bacterium Sporosarcina pasteurii (S. pasteurii). This engineered living material (ELM) has the potential to self-repair, making it a compelling low-emission alternative to conventional concrete.
Background
ELMs are a growing class of materials that incorporate living cells to enable functions like self-healing, self-assembly, and photosynthesis. Among these, some microbes are capable of microbially induced calcium carbonate precipitation (MICP), a form of biomineralization that can strengthen structures while operating at lower temperatures and carbon costs than traditional cement production.
However, current biomineralized ELMs face important constraints. Their viability is typically short-lived, often limited to a few days or weeks, and they require highly controlled environments to remain functional. Moreover, existing processes offer limited control over the internal architecture of the material, a critical factor when optimizing mechanical performance or tailoring biological characteristics.
This study addresses both issues by proposing a fungal-based scaffold. The researchers chose non-pathogenic N. crassa for its ability to perform ureolytic MICP. Its mycelium, which forms a dense, root-like network, offers a biologically structured scaffold that can support complex geometries and facilitate mineralization.
Approach
To explore this concept, the team designed three mineralization pathways: one using the fungus alone, another incorporating bacterial mineralization, and a third relying on chemical (abiotic) precipitation.
In the fungal-induced setup, N. crassa was grown in two media types, FICP-malt and FICP-def, to encourage calcium carbonate formation. Over a ten-day period, researchers sampled the liquid medium to monitor dissolved calcium and urea levels. At the end of the cycle, fungal biomass was collected, filtered, and dried for further testing.
To test bacterial mineralization (BICP), fungal scaffolds were first cultured in nutrient broth without calcium or urea, then sterilized. These autoclaved scaffolds were then inoculated with S. pasteurii, allowing the bacterium to initiate mineralization without interference from the fungal metabolism.
For abiotic mineralization (AICP), sterilized mycelium was placed in a calcium chloride solution, followed by sodium bicarbonate. The pH was then raised using sodium hydroxide to chemically induce calcium carbonate precipitation.
Each method was assessed using colorimetric assays to track calcium and urea levels, and acid digestion to measure how much mineral was deposited. Structural and compositional analyses were performed using scanning electron microscopy (SEM) and X-ray diffraction. To evaluate the material's practical potential, the mineralized scaffolds were also used to fabricate osteon-inspired microstructures—cylindrical forms that mimic natural bone architecture.
Findings
The fungal-only scaffolds mineralized effectively, with both FICP-malt and FICP-def samples losing two to three times more mass during acid digestion than unmineralized controls, indicating substantial mineral deposition. Interestingly, FICP-def scaffolds exhibited 20 % greater mass loss than their FICP-malt counterparts, pointing to more efficient biomineralization, likely driven by higher ureolytic activity or biomass concentration.
In comparison, bacterial mineralization was notably faster and more effective. Within just 24 hours, BICP scaffolds hydrolyzed all dissolved urea and removed nearly 97 % of calcium from solution, far exceeding the performance of the fungal-only systems. For context, planktonic (free-floating) bacteria achieved just 35–39 % removal of these compounds in the same timeframe.
Visual evidence supported these findings. SEM images revealed mineral deposits coating fungal hyphae in the presence of S. pasteurii, while samples lacking calcium showed far less bacterial attachment. These results underscored the effectiveness of bacteria-driven mineralization and the importance of the chemical environment.
Mechanical testing further highlighted performance differences. Nanoindentation revealed that FICP-def scaffolds produced minerals 276 % stiffer than those from the FICP-malt condition. BICP scaffolds delivered even more dramatic improvements—632 % stiffer than FICP-malt and 230 % stiffer than FICP-def. The lower modulus in FICP-malt samples may be due to a softer calcium carbonate phase or organic inclusions during mineral formation.
The osteon-inspired structures created from these scaffolds were structurally distinctive. Both SEM and microcomputed tomography confirmed the presence of concentric mineralized rings. Between sand particles embedded in the scaffold, crushed mineralized mycelium appeared as a less dense filler, showing how the material integrates with granular components.
Conclusion
This study offers compelling evidence that fungal mycelium can serve as a viable scaffold for engineered living materials. Both fungal- and bacteria-based approaches demonstrated strong mineralization potential while maintaining the viability of the living fungal component in the self-mineralizing systems.
Still, there are limitations to address. Co-culturing N. crassa with S. pasteurii wasn’t viable, meaning the fungal scaffold had to be sterilized before bacterial mineralization could proceed. And while the team successfully built structures with intricate internal architecture, their mechanical properties remain a work in progress.
Nonetheless, these early results lay important groundwork for developing sustainable alternatives to traditional building materials. By harnessing the self-organizing properties of fungal mycelium and the mineralizing capabilities of microbes, researchers are edging closer to construction materials that are not only environmentally friendly but also smart, adaptive, and structurally sound.
Journal Reference
Viles, E. et al. (2025). Mycelium as a scaffold for biomineralized engineered living materials. Cell Reports Physical Science, 6(4). DOI: 10.1016/j.xcrp.2025.102517, https://www.cell.com/cell-reports-physical-science/fulltext/S2666-3864(25)00116-X
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