Earth-building materials offer a low-carbon option for construction, but their poor water resistance limits their adoption by the construction industry. Adding biopolymers to earth materials can improve mechanical strength and water resistance but also promote mold mycelium growth that reduces indoor air quality. However, for other applications such as insulation or packaging, the controlled growth of specific mycelium is seen as a promising option for producing natural waterproof materials. These application require heat-inactivation to kill the mycelium and preserve air quality. It is currently unknown if heat-inactivated mold mycelium could improve the water resistance of earth materials. This study explores a new design by promoting the natural growth of molds on biostabilized earth materials and studying the effect on earth material properties after heat inactivation. Earth mortars were prepared by mixing soil, water, and biopolymers (2 % of soil mass) to a consistent texture. Twenty formulations, using two soils and four biopolymers, were subjected to two different 21-day cures, under dry (oven at 50 degrees C) or humid (30 degrees C, 98 % RH) conditions. Mortar properties were investigated after a 48-h 80 degrees C heat treatment to inactivate mold. We found that the humid cure consistently prompted mold growth on biostabilized mortars, which was associated with significantly higher water resistance compared to unexposed mortars. Specifically, capillary water absorption and mass loss after water spray was reduced by 28 % and 64 % respectively. These improvements were achieved with minimal impact on shrinkage, density, and mechanical strength. The amelioration in water resistance was attributed to the hydrophobic mold mycelium filling the earth mortar pore as observed by UV microscopy. Together, this study demonstrates that mycelium could dramatically improve the water resistance of biostabilized earth materials.

This study explored mycelium-based composites (MBCs) as a sustainable alternative to conventional materials, focusing on the role of lignocellulosic substrates in optimizing their physical, mechanical, and biodegradability properties. It also addressed the valorization of agroforestry by-products, particularly European hazelnut shells (HZ) and radiata pine sawdust (SW), in an effort to reduce waste and minimize environmental impacts. The MBCs were obtained using two formulations (HZ100 and HZ75-SW25) of local agroforestry by-products bound together with natural growth of fungal mycelium from Ganoderma sp. We examined the physical and mechanical properties of these novel materials, including the density, shrinkage, water absorption, hydrophobicity, moduli of rupture and elasticity, and internal bond strength. Additionally, we assessed the biodegradability of the MBCs in soil to estimate the time required for complete degradation. The results clearly indicated differences in performance between the MBCs from HZ100 and HZ75-SW25. In general, HZ75-SW25 demonstrated superior mechanical performance compared to HZ100. Water absorption was low in both cases, suggesting a degree of hydrophobicity on the surface. The biodegradation results indicated that the fabricated MBCs could fully decompose in less than one year when buried in soil, confirming that these biocomposites are entirely biodegradable.

This work explored whether partial cellulose bioconversion with fungal mycelium can improve the properties of cellulose fibre-based materials. We demonstrate an efficient approach for producing cellulose-mycelium composites utilizing several cellulosic matrices and show that these materials can match fossil-derived polymeric foams on water contact angle, compression strength, thermal conductivity, and exhibit selective antimicrobial properties. Fossil-based polymeric foams commonly used for these applications are highly carbon positive, persist in soils and water, and are challenging to recycle. Bio-based alternatives to synthetic polymers could reduce GHG emissions, store carbon, and decrease plastic pollution. We explored several fungal species for the biofabrication of three kinds of cellulosic-mycelium composites and characterized the resulting materials for density, microstructure, compression strength, thermal conductivity, water contact angle, and antimicrobial properties. Foamed mycelium-cellulose samples had low densities (0.058 - 0.077 g/cm3), low thermal conductivity (0.03 - 0.06 W/m center dot K at + 10 degrees C), and high water contact angle (118 - 140 degrees). The recovery from compression of all samples was not affected by the mycelium addition and varied between 70 and 85%. In addition, an antiviral property against active MS-2 viruses was observed. These findings show that the biofabrication process using mycelium can provide water repellency and antiviral properties to cellulose foam materials while retaining their low density and good thermal insulation properties.

Mycelium-based composites are a promising avenue for innovating sustainable materials from the hyphae of fungi. This study focuses on the use of fibers from four local fungal species, namely, Pleurotus ostreatus, Pleurotus sajor-caju (Fr. Singer), Auricularia auricula-judae, and Schizophyllum commune Fr., to produce mycelium-based composites from water hyacinth. An inoculum of each of the mushroom species was cultivated on PDA medium at 25 and 30 degrees C to determine the optimal temperature based on the growth rate. The obtained optimal condition was used to grow the fungi on water hyacinth (WH) mixed with rice bran in different proportions (100% WH, 70% WH, and 50% WH) with various numbers of fungal inocula (10, 20, and 30 plugs). The obtained composites were coated with a solution of either starch, chitosan, or epoxy resin. Schizophyllum commune Fr. exhibited the highest growth rate and fiber density, with a growth rate of 1.45 +/- 1.92 mm/day at 30 degrees C. Ten inocula of Schizophyllum commune Fr. incubated at 30 degrees C for seven days on a mixture of 50% WH and 50% rice bran gave the optimal composite. Coating the obtained composite with chitosan improved its mechanical properties, but coating it with epoxy resin improved its water absorbency. Buried in soil, the composite coated with a chitosan solution decomposed within 30 days. The results indicate that Schizophyllum commune Fr. can be used as a binder to produce mycelial composites on a substrate of WH mixed with rice bran. The implications of these results will enable the further development and tuning of mushroom-based materials, especially for the production of sustainable bio-construction materials derived from local mushrooms and bio-waste.

Fungi adapt to their surroundings, modifying their behaviors and composition under different conditions like nutrient availability and environmental stress. This perspective examines how a basic understanding of fungal genetics and the different ways that fungi can be influenced by their surroundings can be leveraged toward the production of functional mycelium materials. Simply put, within the constraints of a given genetic script, both the quality and quantity of fungal mycelium are shaped by what they eat and where they grow. These two levers, encompassing their global growth environment, can be turned toward different materials outcomes. The final properties of myco-materials are thus intimately shaped by the conditions of their growth, enabling the design of new biobased and biodegradable material constructions for applications that have traditionally relied on petroleum-based chemicals.This perspective highlights aspects of fungal genetics and environmental adaptation that have potential materials science implications, along the way touching on key studies, both to situate the state of the art within the field and to punctuate the viewpoints of the authors. Finally, this work ends with future perspectives, reinforcing key topics deemed important to consider in emerging myco-materials research. This perspective aims to critically explore the different levers that can be turned to obtain functional and reliable myco-materials engineered from fungi. These levers include fungal species, encompassing their specific set of genetic information, as well as global environmental cues, encompassing aspects of nutrition, that can be used to coax end material properties toward a desired outcome via fungal adaptation.image