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Features of disruption mutants of genes encoding for hydrophobin Vmh2 and Vmh3 in mycelial formation and resistance to environmental stress in Pleurotus ostreatus

Summary

This research investigated how two specific proteins (Vmh2 and Vmh3) help oyster mushrooms grow and protect themselves. These proteins create water-repelling surfaces on fungal cells and help the mushroom adapt to different environments. The study revealed that while both proteins work together to create protective surfaces, one protein (Vmh3) is particularly important for helping the fungus resist environmental stresses and grow properly. Impacts on everyday life: – Improved understanding of how mushrooms grow could lead to better cultivation methods for edible mushrooms – Knowledge of natural water-repelling proteins could inspire new water-resistant materials and coatings – Better understanding of fungal growth mechanisms could help control unwanted fungal growth in buildings or crops – Could lead to development of more stress-resistant mushroom strains for food production – May contribute to new biotechnology applications using fungal proteins

Background

Hydrophobins are small-secreted proteins containing approximately 100 amino acids that are exclusively secreted by filamentous fungi. They can self-assemble into amphiphilic films at hydrophobic-hydrophilic interfaces and are typically divided into two classes based on hydrophobicity and solubility. In Pleurotus ostreatus, more than 20 putative hydrophobin genes have been predicted, with vmh2 and vmh3 being predominantly expressed in vegetative mycelium.

Objective

To investigate the physiological functions of Vmh2 and Vmh3 hydrophobins in vegetative growth of P. ostreatus through analysis of single and double disruption mutant strains.

Results

Both Vmh2 and Vmh3 were found essential for maintaining surface hydrophobicity of mycelium. The Δvmh3 and Δvmh2Δvmh3 strains showed slower aerial mycelia formation on liquid medium, while Δvmh2 strains showed no significant changes. Only Δvmh3 and Δvmh2Δvmh3 strains exhibited reduced growth compared to wild-type under stress conditions involving SDS and H2O2. All disruption strains lost the black aggregates localized between cell wall and external environment, with Δvmh2Δvmh3 showing smoother hyphal surfaces.

Conclusion

Vmh2 and Vmh3 play major roles in hydrophobization of vegetative mycelia, with both proteins likely localized at the interface between cell wall and outer environment. Vmh3, but not Vmh2, contributes to mycelial resistance toward environmental stresses and aerial mycelia formation. These findings suggest that Agaricomycetes have evolved multiple hydrophobins with specific functions to adapt to various environments.
  • Published in:FEMS Microbiology Letters,
  • Study Type:Laboratory Research,
  • Source: 10.1093/femsle/fnad036
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