Nature's Blueprint

How Scientists Are Hacking the Tinder Fungus to Grow Sustainable Materials

The Ancient Fungus Powering Our Sustainable Future

For over 5,000 years, humans have carried Fomes fomentarius—the hardy "tinder fungus"—as kindling, from Ötzi the Iceman's toolkit to modern foraging kits ¹ . Today, this unassuming polypore mushroom is poised to revolutionize sustainable manufacturing.

With its ability to transform agricultural waste into durable, biodegradable materials, F. fomentarius offers a solution to our plastic pollution crisis. But until recently, scientists struggled to reliably control the material properties of fungal composites. The breakthrough came when researchers decoded the fungus's genetic instruction manual through transcriptional analysis—revealing how its genes "turn on" during biomaterial production ¹ .

Fomes fomentarius

Also known as the tinder fungus, this species has been used by humans for millennia and now serves as a model for sustainable biomaterials.

The Language of Life: How Genes "Speak" to Build Materials

What Is a Transcriptional Landscape?

Every cell contains thousands of genes, but not all are active at once. The transcriptional landscape maps which genes are "switched on" (transcribed into RNA) under specific conditions—like a real-time blueprint of biological processes. For F. fomentarius, understanding this landscape reveals:

Degradation Machinery: Enzymes that break down wood (e.g., lignin-modifying peroxidases).
Building Blocks: Genes that construct fungal cell walls (e.g., chitin synthases).
Control Systems: Transcription factors (TFs) that act as "master switches" coordinating these processes ¹ ² .

Co-expression networks—computational models linking genes with similar activity patterns—are key to interpreting this landscape. When Gene A and Gene B activate together across 27 different growth conditions, they likely participate in the same biological pathway ¹ .

Co-expression Network

Visualization of gene co-expression patterns in F. fomentarius showing clustered functional groups.

Gene Activation Timeline

Temporal activation of key gene groups during fungal material production.

Decoding the Fungal Factory: A Landmark Experiment

The Quest

Identify genes controlling F. fomentarius's ability to bind hemp/rapeseed waste into robust composites .

Methodology: From Fungus to Data

Cultivation:
- Grown on 9 laboratory substrates (e.g., agar) + 18 biomaterial conditions (e.g., hemp shives, pine/birch wood) ¹ ² .
- Birch wood induced faster growth than pine—a clue to substrate-specific gene activity ² ³ .
RNA Extraction:
- Sampled mycelium at multiple growth stages.
- Extracted RNA using NucleoSpin Kits ⁷ .
Sequencing & Analysis:
- RNA sequenced (~50 million reads/sample).
- Mapped to F. fomentarius genome (14,757 genes) ¹ .
- Built co-expression networks using Spearman correlation and custom scripts ¹ ⁶ .

Research Process

Scientists analyzing fungal samples in the laboratory setting.

Key Results: The Genetic Architects of Biomaterials

Master Regulator Discovered: The TF CacA showed strong co-expression with chitin/glucan synthases and Rho GTPases—genes critical for hyphal branching and adhesion. Engineering CacA could enhance material density ¹ ⁴ .
Degradation Specialists: 104 carbohydrate-active enzymes (CAZymes) were cataloged. Birch (angiosperm) triggered 30% more CAZyme upregulation than pine (gymnosperm), explaining its superior decomposition rate ¹ ² ⁴ .

Key Genes Governing Biomaterial Production

Gene Category	Key Genes	Function in Biomaterials
Transcription Factors	CacA, CalB	Activate chitin/cell wall synthesis
Chitin Synthases	CHS1, CHS3	Strengthen mycelial network
Lignin Modifiers	AA2 (peroxidases), GH10 (xylanases)	Break down plant lignin
Transporters	MFS sugar transporters	Import wood-derived sugars

CAZyme Upregulation in Birch vs. Pine

Comparative transcriptomics of angiosperm/gymnosperm decay ² ⁴

Contiguous Gene Clusters: Unusual "gene neighborhoods" were discovered—like a cluster housing a lipase, kinase, and chitin synthase—all co-expressed and physically adjacent. These may enable rapid response to new substrates ¹ ⁹ .

The Biomaterial Revolution: From Genes to Products

F. fomentarius composites outperform expanded polystyrene (EPS) in compressive strength at 50% strain (0.3 MPa vs. 0.15 MPa) . Transcriptional insights enable precision engineering of these materials:

Substrate Optimization: Birch/hemp waste induces ideal CAZyme profiles for rapid growth.
Strain Design: Overexpressing CacA could accelerate hyphal networking.
Cluster Utilization: Harnessing contiguous gene blocks may boost enzyme efficiency ¹ .

Essential Research Reagents

Reagent/Resource	Role in Research	Example in Study
RNA Extraction Kits	Isolate high-quality RNA	NucleoSpin® RNA Plant Kit ⁷
Co-expression Scripts	Build gene networks	Custom Spearman-based Python scripts ¹
CAZyme Databases	Annotate enzymes	dbCAN2, CAZy ¹
AntiSMASH	Predict gene clusters	Identified 39 non-toxic clusters ¹

Sustainable Future

Fungal-based materials offer a biodegradable alternative to conventional plastics and synthetic materials.

Conclusion: The Future Is Fungal

Transcriptional landscapes are more than just data—they're blueprints for a sustainable revolution. As we edit CacA or design substrates that "talk" to fungal genes, we inch closer to drop-in replacements for plastics, leather, and construction materials. With its 5,000-year human partnership, F. fomentarius reminds us that nature's solutions are often the most enduring ¹ .

"These co-expression networks are like Rosetta Stones—they let us speak the fungus's language and ask: How will you build for us?"

Timothy Cairns, Co-author of the landmark 2025 study ⁹