Gene Editing Oyster Mushrooms Could Make Fungal Materials Stronger
- Gauri Khanna
- 14 minutes ago
- 4 min read
Researchers at Kyoto University and Chosun University used CRISPR/Cas9 to disable gene mbp1 in Pleurotus ostreatus, producing mycelium mats that were approximately 30% stiffer and 50% stronger in tension than unedited controls.
The edited fungal strains also produced harder mycelium-based composites under compression testing, and lost the ability to form fruiting bodies, which simplifies industrial production by keeping the fungus in its material-forming growth phase.
This is the first published study demonstrating that targeted genetic modification can directly improve the mechanical performance of mycelium-based composites, opening a new route beyond trial-and-error strain screening.
Researchers in Japan and South Korea have used CRISPR to switch off a single gene in Pleurotus ostreatus, producing denser mycelium and measurably stronger materials. It is the first time molecular breeding has been shown to improve mycelium-based composites.
Why Mycelium Materials Have Hit a Mechanical Ceiling
The appeal of mycelium-based materials is well established: biodegradable, producible at room temperature from agricultural waste, and requiring no synthetic resins. Yet for all the commercial interest in fungal packaging, insulation, and leather alternatives, a persistent weakness has limited wider adoption. Mechanical strength, how well a material resists pulling apart or being crushed, has remained stubbornly modest. Most mycelium composites behave more like polystyrene foam than structural material, with tensile strengths typically well below 1 MPa. Years of optimising cultivation conditions and screening fungal species from nature have yielded incremental gains at best.
A new study published in Applied Microbiology and Biotechnology (Kojima et al., 2026) takes a different approach: rather than changing what fungi are fed or how they are grown, the researchers changed the fungi themselves.
Switching Off a Single Gene Changes How the Fungus Builds Its Cell Wall
The target was a gene called mbp1, which encodes a transcription factor, essentially a molecular switch that controls the activity of other genes, involved in cell wall construction and normal mycelial growth in Pleurotus ostreatus, better known as the oyster mushroom.
Using the CRISPR/Cas9 system (think of it as a precise molecular scissors that can cut and disable a specific gene), the team at Kyoto University disabled mbp1 in both copies of the fungal genome. Because P. ostreatus naturally exists in a two-nucleus cellular state called a dikaryon (which grows faster and is better suited to material production than the single-nucleus form) the researchers generated dikaryotic strains carrying the disruption in both nuclei before testing their properties.
The edited strains grew about 19% more slowly than the control and, notably, lost the ability to produce fruiting bodies (mushrooms) entirely. While the latter might seem like a drawback, it is not necessarily so for material production: a fungus that cannot fruit is less likely to redirect its energy away from mycelial growth and towards reproductive structures, which could improve consistency in manufacturing settings (Chang et al., 2019).
Denser Mats, Stronger Materials: The Mechanical Results
When mycelium mats (the thin sheets of aerial hyphae (the fine filaments that make up fungal tissue) grown on the surface of a substrate) were produced from the edited strains and tested mechanically, the differences were measurable. Young's modulus, a standard measure of material stiffness (how much a material resists deformation under load), increased by approximately 30% in the edited strains compared to the control, reaching around 1,385 MPa versus 1,029 MPa. Ultimate tensile strength (the point at which the material breaks) rose from roughly 7.9 MPa to approximately 11.9 MPa, an increase of around 50% (Kojima et al., 2026).
The underlying reason appears to be density. The edited mats were thinner but weighed about the same as the controls, meaning the fungal tissue was packed more tightly together. A strong positive correlation was found between mat density and Young's modulus (R²=0.80): in plain terms, denser mats were reliably stiffer mats. The researchers attribute this to a reduced ability to form aerial hyphae that extend upward into the air: when hyphae grow outward rather than upward, they produce a more compact, less porous structure.
Chemical analysis using infrared spectroscopy (a technique that identifies molecular components by how they absorb light) found that the edited strains contained less protein relative to polysaccharides (the structural sugars, including glucans and chitin, that form the fungal cell wall). Since proteins are thought to act as plasticisers that make cell walls more flexible rather than rigid, a lower protein-to-polysaccharide ratio likely contributes to increased stiffness (Haneef et al., 2017; Gow and Lenardon, 2023).
From Mats to Composites: The Packaging and Construction Implications
Beyond the mycelium mats, the edited strains also produced harder mycelium-based composites: the denser, substrate-bound materials used in packaging and construction applications. Compressive strength increased from 0.58 MPa in the control to 0.73 MPa in the edited strains, roughly a 25% improvement.
These numbers remain modest in absolute terms; mycelium composites are not competing with steel or structural timber. But the direction of travel is clear, and the significance here is methodological as much as numerical. Previous attempts to improve mycelium materials have largely relied on screening wild fungal strains or adjusting growth substrates: an approach constrained by whatever nature happens to offer. Molecular breeding, by directly editing the genome, opens a more systematic path: identify which genes control density, cell wall composition, or hyphal architecture, and adjust them deliberately.
The same logic that has transformed crop breeding and pharmaceutical production over the past two decades (that targeted genetic modification can improve on what natural variation provides) is now being applied to fungal biomaterials. Whether it will prove similarly transformative depends on how many of the relevant genetic levers remain to be found, and on the regulatory and public acceptance environment for genetically modified organisms in material applications. For now, this study establishes that the levers exist.
