Mycelium-Composite Materials-A Promising Alternative to Plastics?

Abstract

Plastic waste inefficiently recycled poses a major environmental concern attracting attention from both civil society and decision makers. Counteracting the phenomenon is an important challenge today. New possibilities are being explored to find alternatives to plastics, and one of them refers to mycelium-composite materials (MCM). Our study aimed at investigating the possibility of using wood and litter inhabiting basidiomycetes, an underexplored group of fungi that grow fast and create strong mycelial mats, to produce biodegradable materials with valuable properties, using cheap by-products as a substrate for growth. Seventy-five strains have been tested for their ability to grow on low-nutrient media and to form compact mycelial mats. Eight strains were selected further for evaluation on several raw substrates for producing in vitro myco-composites. The physico-mechanical properties of these materials, such as firmness, elasticity and impermeability, were analyzed. Abortiporus biennis RECOSOL73 was selected to obtain, at the laboratory scale, a real biodegradable product. Our results suggest that the strain used is a promising candidate with real possibilities for scalability. Finally, corroborating our results with scientific available data, discussions are being made over the feasibility of such technology, cost-effectiveness, scalability, availability of raw materials and, not least, where future studies should be directed to.

Keywords: Abortiporus biennis; biodegradable materials; fungal cultures; mycelial composites.

Figure 1

Obtaining the final material with A. biennis RECOSOL73 strain grown on wheat bran-sawdust substrate ((a–c)—molding the substrate; (d,e)—the final product).

Figure 2

MCMs obtained with A. biennis RECOSOL73, a-f: mycelium growth after 3 weeks incubation on 9 cm diameter Petri dishes; (g–i): dried material ((a,g)—on wheat bran; (b,h)—on wheat straws; (c,i)—on sawdust; (d,j)—on wheat bran + wheat straws; (e,k)—on wheat bran + sawdust; (f,i)—on wheat bran + coconut husk fibers).

Figure 3

Mass increase during water uptake of material when soaked as cut fragments (**** significant differences for p < 0.0001).

Figure 4

Analysis under stereomicroscope (15–35× magnification) of the material structure after exposure to high temperature ((a–c)—inner surface; (d–f)—outer surface; (g–i)—internal section; (a,d,g)—initial structure; (b,e,h)—after 1 h at 150 °C; (c,f,i)—after 2 h at 200 °C).

Figure 5

Structure of the MCM analyzed under stereomicroscope (20–40×): (a,b)—inner surface; (c)—outer surface; (d–h)—section).

Figure 6

Surface structure of dried material seen under electron microscopy (SEM): (a,c,d,f,g)—upper surface; (b,e,h,i,j,k)—bottom surface.