Waste-Derived Low-Cost Mycelium Nanopapers with Tunable Mechanical and Surface Properties

Abstract

Mycelium, the vegetative growth of filamentous fungi, has attracted increasing commercial and academic interest in recent years due to its ability to upcycle agricultural and industrial wastes into low-cost, sustainable composite materials. However, mycelium composites typically exhibit foam-like mechanical properties, primarily originating from their weak organic filler constituents. Fungal growth can be alternatively utilised as a low-cost method for ondemand generation of natural nanofibrils, such as chitin and chitosan, which can be grown and isolated from liquid wastes and by-products in the form of fungal micro-filaments. This study characterised polymer extracts and nanopapers produced from a common mushroom reference and various species of fungal mycelium grown on the sugarcane by-product molasses. Polymer yields of ~10-26% were achieved, which is comparable to those of crustacean-derived chitin, and the nanopapers produced exhibited much higher tensile strengths than existing mycelium materials, with values of up to ~25 MPa (mycelium) and ~98 MPa (mushroom), in addition to useful hydrophobic surface properties resulting from the presence of organic lipid residues in the nanopapers. HCl or H 2 O 2 treatments were used to remove these impurities facilitating tuning of mechanical, thermal and surface properties of the nanopapers produced. This potentially enables their use in a wide range of applications including coatings, membranes, packaging and paper.

Crab vs. Mushroom: A Review of Crustacean and Fungal Chitin in Wound Treatment

“…Fungal β-glucans, such as lentinan from L. edodes (shiitake), schizophyllan from S. commune (split gill), zymosan from S. cereviase (baker's yeast), pleuran from P. ostreatus (oyster), and ganoderan from G. lucidum (reishii), have also been extensively studied due to the human immune system's ability to recognize them, promoting immune stimulation, antibacterial, antitumor, anticancer, and antioxidant properties [92][93][94][95]. These findings, coupled with the varying chitin, chitosan, and polysaccharide profiles of the over 5.1 million species of fungi in existence [96] and recent advances in fungal material technology [7,14,17,[97][98][99][100][101], suggest that fungi-derived wound treatments warrant further investigation. In particular, the native chitin-β-glucan composite architecture of fungal chitin could be utilized to achieve scaffolds exceeding the mechanical performance of crustacean chitin [17] and novel antibacterial properties resulting from composite dressings incorporating naturally generated complexes of fungal chitin, chitosan, β-glucans, and exopolysaccharides could pave the way for new low-cost, natural, and mass-producible dressing technologies.…”

“…compared to total source mass, chitin contents, and other major organic and inorganic constituents listed. Data from [14,[18][19][20][21][22][23][24][25][26][27][28][29][30]. Both crustacean and fungal chitin have a similar molecular structure to cellulose, which is the structural component of the primary cell wall of all green plants, algae, and oomycetes.…”

Agricultural and Biomedical Applications of Chitosan-Based Nanomaterials

“…Additionally, chitinous cell wall material was isolated from yeast species Rhodosporidium paludigenum and Saccharomyces cerevisiae [ 8 ]. Fungal mycelium of Allomyces arbuscula , Mucor genevensis , Tranetes versicolor, and the fruiting body of Agaricus bisporus were also utilized as more cost-effective and renewable sources for chitin compared to crustacean shells [ 9 ]. A pest attacking agricultural crop in Mexico and Central America, Schistocerca piceifrons piceifrons (Orthoptera: Acrididae) has also been used for the successful extraction of chitin and chitosan at 11.88% and 9.11% yield, respectively [ 10 ].…”

Fungal mycelium classified in different material families based on glycerol treatment

“…Biomass was harvested (leaving mycelial pellets intact), dried and either or not treated with glycerol. Different from Nawawi et al 9 and Jones et al 10 , no extraction steps were applied. Glycerol treatment changed the material properties from being similar to natural materials to those of polymers and elastomers.…”

“…Chitinglucan complexes from fungal mycelium have attracted attention in the bio-based material field. Paper-like nanomaterials consisting of this complex are obtained by soft-compression of homogenised mycelium or fruiting bodies that have been extracted with hot water and mild alkaline 9,10 . The chitin-glucan materials from Agaricus bisporus mushrooms are characterised by Young's modulus (E) and ultimate tensile strength (σ) of approximately 7 GPa and 100-200 MPa, respectively 9 .…”