Hyphal systems and their effect on the mechanical properties of fungal sporocarps

Abstract

Little is known about the mechanical and material properties of hyphae, the single constituent material of Agaricomycetes fungi, despite a growing interest in fungus-based materials. In the Agaricomycetes (the mushrooms and allies), there are three types of hyphae that make up sporocarps: generative, skeletal, and ligative. All filamentous Agaricomycetes can be categorized into one of three categories of hyphal systems that compose them: monomitic, dimitic, and trimitic. Monomitic systems have only generative hyphae. Dimitic systems have generative and either skeletal (most common) or ligative. Trimitic systems are composed of all three kinds of hyphae. SEM imaging, compression testing, and theoretical modeling were used to characterize the material and mechanical properties of representative monomitic, dimitic, and trimitic sporocarps. Compression testing revealed an increase in the compression modulus and compressive strength with the addition of more hyphal types (monomitic to dimitic and dimitic to trimitic). The mesostructure of the trimitic sporocarp was tested and modeled, suggesting that the difference in properties between the solid material and the microtubule mesostructure is a result of differences in structure and not material. Theoretical modeling was completed to estimate the mechanical properties of the individual types of hyphae and showed that skeletal hyphae make the largest contribution to mechanical properties of fungal sporocarps. Understanding the contributions of the different types of hyphae may help in the design and application of fungi-based or bioinspired materials. Statement of SignificanceThis research studies the material and mechanical properties of fungal sporocarps and their hyphae, the single constituent material of Agaricomycetes fungi. Though some work has been done on fungal hyphae, this research studies hyphae in context of the three hyphal systems found in Agaricomycetes fungi and estimates the properties of the hyphal filaments, which has not been done previously. This characterization was performed by analyzing the structures and mechanical properties of fungal sporocarps and calculating the theoretical mechanical properties of their hyphae. This data and the resulting conclusions may lead to a better design and implementation process of fungi-based materials in various applications using the properties now known or calculated.