Scientists Breed Custom Mushrooms for Green Materials

McMaster University researchers have unlocked a new approach to creating sustainable materials by breeding mushrooms with specific genetic traits.

Using the split gill mushroom—a species with extraordinary genetic diversity that includes over 23,000 different mating types—scientists demonstrated how natural genetic variations can be harnessed to produce customized biodegradable materials with dramatically different properties.

The team bred four mushroom strains from around the world to create 12 new genetic combinations, then processed their fungal networks into films that varied widely in strength, flexibility, and water resistance. This genetic approach could revolutionize how manufacturers create eco-friendly alternatives to plastics, textiles, and packaging materials.

The Challenge of Mushroom Manufacturing

While mushroom-based materials are already being used to create everything from vegan leather to foam alternatives, manufacturers face a persistent problem. Even when grown and processed identically, different mushroom strains can produce materials with vastly different properties—some strong but brittle, others flexible but weak.

“This is the first study to examine how genetic variation within a species could potentially influence material properties so we can tailor materials for specific purposes,” explains Jianping Xu, a professor of biology at McMaster University and the study’s senior author.

The split gill mushroom serves as an ideal testing ground for this genetic approach. Found on every continent except Antarctica, this cosmopolitan species possesses remarkable genetic diversity that researchers can tap into for material development.

Breeding Better Materials

The research team selected four mushroom strains from different geographic regions—Ecuador, Mexico, Massachusetts, and Russia—each carrying distinct genetic blueprints. Through controlled breeding, they created 12 new strains with unique combinations of nuclear and mitochondrial DNA.

What makes this approach particularly sophisticated is how the researchers tracked both nuclear genes (inherited from both parents) and mitochondrial genes (inherited from just one parent). This dual inheritance system creates even more genetic combinations than traditional breeding alone would produce.

The team grew these 16 strains in liquid culture to form fluffy mats of mycelium—the thread-like structures that make up a mushroom’s body. These mats were then processed into films using two different chemical treatments: polyethylene glycol and glycerol.

Key Research Findings:

• Films varied dramatically in strength—some were two orders of magnitude stronger than others
• Mitochondrial genetics significantly influenced growth patterns and material yield
• Nuclear-mitochondrial interactions created unique material properties in each strain
• Different chemical treatments revealed hidden genetic potential in the materials
• No single strain was best at everything—each excelled in different properties

The Genetics Behind Material Properties

The study revealed complex interactions between genetics and material performance that extend far beyond what manufacturers currently understand. Strains with different mitochondrial lineages showed distinct growth characteristics, with some growing faster and producing more biomass than others.

More surprisingly, the interaction between nuclear and mitochondrial genetics proved crucial for determining final material properties. This finding suggests that the cellular powerhouses—mitochondria—play an unexpectedly important role in determining how strong or flexible the resulting materials become.

When treated with polyethylene glycol, the materials became stiffer and stronger but more brittle. Glycerol treatment produced softer, more flexible films. However, different genetic strains responded uniquely to each treatment, creating a complex matrix of possible material properties.

Beyond Simple Breeding: The Molecular Picture

Using advanced chemical analysis techniques, the researchers discovered that different genetic strains actually have distinct molecular fingerprints in their cell walls. Fourier transform infrared spectroscopy revealed that strains varied in their protein content, sugar composition, and structural molecules like chitin and beta-glucans.

These molecular differences help explain why some strains respond better to certain treatments than others. The chemical crosslinkers interact differently with each strain’s unique cellular architecture, producing materials with varied properties from the same basic process.

The team also found that surface morphology varied dramatically between treatments and strains. Some films developed dense networks of fibers visible under electron microscopy, while others formed smooth, almost melted-looking surfaces. These structural differences translated directly into different mechanical properties.

What This Means for Green Manufacturing

This genetic approach to material design addresses a fundamental challenge in sustainable manufacturing. Currently, companies working with mushroom-based materials often struggle with inconsistent properties that make it difficult to create reliable products.

“It’s possible to use natural genetic variation that already exists in nature and to make combinations that will potentially fit into all kinds of materials, not just one,” says Xu.

The implications extend beyond simple material replacement. Different applications require different properties—packaging needs water resistance, textiles need flexibility, and building materials need strength. By understanding how genetics influences these properties, manufacturers could breed specific strains for specific applications.

The research also revealed that some genetic combinations that don’t exist in nature could theoretically be created through laboratory techniques. The scientists identified optimal genetic profiles for certain properties that could be achieved through protoplast fusion—a technique that artificially combines cellular components from different strains.

The Untapped Potential of Fungal Diversity

Perhaps most intriguing is what the study suggests about undiscovered potential. The researchers worked with just four parent strains, but the split gill mushroom exists in thousands of naturally occurring varieties worldwide. Each represents a potential source of new material properties.

The team’s analysis showed that even within their limited sample, they could identify genetic profiles that would theoretically produce superior materials—combinations that don’t currently exist in their strain collection but could be created through targeted breeding or genetic techniques.

Additionally, the study focused only on film production, but mushroom materials can be processed into foams, leathers, packaging, and even building materials. Each application might benefit from different genetic optimizations, suggesting vast untapped potential for strain-specific material development.

Challenges and Future Directions

The research does face practical limitations. Some of the most promising genetic combinations produced materials too fragile to test without chemical treatment, limiting researchers’ ability to understand the individual contributions of different genetic factors.

Industrial scaling presents another challenge. While the genetic approach works in laboratory conditions, maintaining consistent genetic profiles in large-scale production requires careful quality control and genetic preservation techniques already used in mushroom farming.

Despite these challenges, the study demonstrates that sustainable materials don’t have to be one-size-fits-all solutions. By harnessing the natural genetic diversity that already exists in mushrooms, manufacturers could develop specialized materials optimized for specific applications—some designed for strength, others for flexibility, and still others for water resistance or other properties.

This represents a shift from trying to engineer better processing techniques to instead engineering better organisms. Rather than fighting against natural variation in mushroom materials, this approach embraces that variation as a feature to be optimized and controlled.

The research opens up exciting possibilities for creating truly sustainable materials that can compete with traditional plastics and textiles not just on environmental grounds, but on performance characteristics tailored to specific applications.