Fine-Tuning of Physicochemical Properties and Growth Dynamics of Mycelium-Based Materials.

Plastic pollution is becoming one of the most critical global problems nowadays. On the other hand, polymers are very versatile materials, and their products cannot be eliminated totally, but alternatives must be found. A very promising candidate is fungal mycelium. It is a self-growing, natural material, made of well-organized natural polymers, whose morphology, hydrodynamic, and mechanical properties can be tuned by changing the substrate of growth. In this work, we show that even small modifications in the composition of a standard fungal growth medium, potato dextrose broth (PDB), can induce significant differences in the morphology, chemical, and hydrodynamic properties of mycelium. The growth rate of mycelium is also influenced by the substrate of growth. Mycelium materials grown in PDB enriched with d-glucose are highly porous, thicker, and more apt to adsorb moisture with respect to mycelium materials grown in PDB with a small quantity of lignin. The latter, on the other hand, grow very fast, following a concentric pattern, and are denser and less hydrophilic. All mycelia are, however, hydrophobic, with water contact angles around 120°. Mycelia have interesting properties, tunable at the nanoscale, and are thus suitable for many applications: the methods used in this work can be applied to different strains and conditions and allow for choosing the best mycelium-based material for any use.