How Mushroom Structures and Chemicals Enhance Their Strength

Jenn Hoskins
14th June, 2024

How Mushroom Structures and Chemicals Enhance Their Strength

The hoof-shaped fruiting body of the fungus Fomes fomentarius (a–d) is composed of four macroscopically distinct segments—the outer crust, trama, hymenium, and central mycelial core—which are identified in a cross-section of the specimen (e).

Image adapted from: Klemm et al. / CC BY (Source)

Key Findings

  • The study by Technische Universität Berlin examined the structural and mechanical properties of the polypore fungus Fomes fomentarius
  • The hymenium segment, despite being the most porous, showed the best mechanical properties due to its high chitin/chitosan content and skeletal hyphae
  • Increased calcium content in the hymenium and crust, confirmed by SEM-EDX, contributes to the fungus's robustness
The natural world has always been a source of inspiration for developing new materials. While the structural properties of wood are well-documented, fungi have not been studied as extensively. A recent study conducted by Technische Universität Berlin delves into the structural and mechanical properties of the polypore fungus Fomes fomentarius[1]. This research could pave the way for the development of advanced materials inspired by the unique characteristics of this fungus. The study focused on the fruiting body of F. fomentarius, which is divided into four segments: crust, trama, hymenium, and mycelial core. Each segment was analyzed for its structural, chemical, and mechanical properties. Special attention was given to the composition of the cell walls, including chitin/chitosan and glucan content, degree of deacetylation (a measure of how much acetyl groups are removed from chitin), and the distribution of trace elements like calcium and potassium. One of the most intriguing findings was that the hymenium, despite being the most porous segment, exhibited the best mechanical properties. This strength is attributed to its high proportion of skeletal hyphae (the thread-like structures that make up the fungus) and the highest chitin/chitosan content in the cell wall. The honeycomb structure of the hymenium also contributes to its robustness. Additionally, an increased calcium content was found in both the hymenium and crust, with calcium oxalate crystals confirmed by scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM-EDX). This study builds on previous research that has highlighted the potential of fungi for various applications. For instance, filamentous fungi from the Basidiomycota phylum have been identified as promising candidates for producing composite materials from agricultural and forestry residues[2]. These fungi can bind and glue loose substrate particles into a mycelial network, creating biological composites that could replace petroleum-based plastics and foams. F. fomentarius has already shown promise in lab-scale production of mycelium composites, demonstrating mechanical properties comparable to synthetic foams like expanded polystyrene (EPS)[2]. Further, the architectural design of F. fomentarius has been a source of inspiration for developing ultralightweight high-performance materials. Previous studies have revealed that F. fomentarius is a functionally graded material with three distinct layers, each exhibiting unique microstructures and mechanical properties due to the synergistic interplay of their features[3]. This new study corroborates these findings by showing how different segments of the fungus have varying structural and compositional characteristics, each contributing to its overall robustness. The chitin-glucan complex (CGC) found in fungi like F. fomentarius is another area of interest. CGC is the main component of fungal cell walls and has various applications in the food and pharmaceutical industries due to its physical and physiological activities[4]. The present study's focus on the chitin/chitosan content and degree of deacetylation in F. fomentarius aligns with earlier research on CGC, further emphasizing the potential of fungi as a sustainable source of valuable materials. In summary, the research conducted by Technische Universität Berlin provides comprehensive insights into the structural and mechanical properties of Fomes fomentarius. By examining the different segments of the fruiting body, the study highlights the importance of considering these varying characteristics when developing fungal-inspired materials. The porous yet robust structure of the hymenium, in particular, offers a promising blueprint for advanced smart materials. This study, along with previous research, underscores the potential of fungi in advancing sustainable material science and contributing to a bio-based circular economy[5].

BiochemPlant ScienceMycology

References

Main Study

1) Hierarchical structure and chemical composition of complementary segments of the fruiting bodies of Fomes fomentarius fungi fine-tune the compressive properties.

Published 13th June, 2024

https://doi.org/10.1371/journal.pone.0304614

Related Studies

2) Establishment of the basidiomycete Fomes fomentarius for the production of composite materials.

https://doi.org/10.1186/s40694-022-00133-y

3) The complex structure of Fomes fomentarius represents an architectural design for high-performance ultralightweight materials.

https://doi.org/10.1126/sciadv.ade5417

4) Characterization of a chitin-glucan complex from the fruiting body of Termitomyces albuminosus (Berk.) Heim.

https://doi.org/10.1016/j.ijbiomac.2019.04.198

5) Growing a circular economy with fungal biotechnology: a white paper.

https://doi.org/10.1186/s40694-020-00095-z


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