"Fungus fashion" gets genetic fit
Natural DNA shuffles in split-gill mushrooms let designers dial stiffness or stretch at will, no CRISPR required
image: Natural DNA shuffles in split-gill mushrooms let designers dial stiffness or stretch at will, no CRISPR required
Credit: Department of Biology, McMaster University, Ontario L8S 4K1, Canada
Leather that snaps like glass or stretches like spandex can now be grown from the same mushroom simply by choosing its parents. By mating four geographically distant lines of the common split-gill fungus Schizophyllum commune, McMaster scientists generated sixteen unique nuclear-mitochondrial genotypes whose mycelial films cover a three-fold range in strength and a ten-fold span in ductility. The work, published in the Journal of Bioresources and Bioproducts, delivers the first "genetic dial" for tuning pure fungal materials without gene editing or chemical additives.
Mycelium composites already replace foam and animal hide, yet performance swings wildly between batches. Industry blames nutrients, humidity or drying cycles; biology was rarely questioned. The new study flips that script, exploiting S. commune’s hyper-variable mating system in which each monokaryon carries one of thousands of distinct nuclei and mitochondria. Pair-wise crosses produced twelve dikaryons that share nuclear DNA but differ in mitochondrial heritage, creating a living library for materials science.
All strains were grown for twelve days in identical liquid broth, harvested as floating mats and treated with either glycerol or polyethylene glycol 400 before slow dehydration. Glycerol-cured films emerged translucent and rubbery, elongating up to 98 % before tearing. PEG-locked sheets became rigid and opaque, reaching specific stiffness of 0.06 GPa·cm³/g—double the best glycerol counterpart—yet some shattered at 2 % strain. Statistical modelling showed that 60 % of the performance gap traces to the interaction between genotype and cross-linker, not the cross-linker alone.
Microscopy explains why: glycerol melts surface hyphae into a fused, crack-stopping mat, while PEG crystallises around chitin micro-fibrils, petrifying aerial filaments. FT-IR spectra reveal strain-specific ratios of β-glucans, chitin and protein that dictate how each plasticiser couples to the wall. Mitochondrial haplotype alone governs hydrophobicity, with δ-cytoplasm strains producing super-wicking films that absorb water in seconds, whereas γ-mitochondria yield contact angles above 90° without extra coatings.
The team mapped the entire palette onto a materials-selection chart. One dikaryon (nuclear αγ plus mitochondrial γ) delivers the highest energy absorption per gram, out-performing earlier S. commune films made with triple the glycerol. Conversely, a βγ combination optimised for strength sits in the same quadrant as polypropylene, hinting at rigid packaging uses. Because strains are stable through successive sub-cultures, a single spore print could seed continent-scale production of "designer" mycelium.
No transgenes, flammable solvents or rare feedstocks are required—just sterile broth and a Petri dish romance. The authors envisage cataloguing thousands more wild isolates, then using protoplast fusion to custom-blend nuclei and mitochondria à la carte. Such a breeding pipeline would let start-ups pick mechanical specs first and grow the exact fungus second, turning mycelium from a boutique curiosity into a predictable engineering platform.