Three-Dimensional Printing of Living Mycelium-Based Composites: Material Compositions, Workflows, and Ways to Mitigate Contamination

Abstract

The construction industry makes a significant contribution to global CO2 emissions. Material extraction, processing, and demolition account for most of its environmental impact. As a response, there is an increasing interest in developing and implementing innovative biomaterials that support a circular economy, such as mycelium-based composites. The mycelium is the network of hyphae of fungi. Mycelium-based composites are renewable and biodegradable biomaterials obtained by ceasing mycelial growth on organic substrates, including agricultural waste. Cultivating mycelium-based composites within molds, however, is often wasteful, especially if molds are not reusable or recyclable. Shaping mycelium-based composites using 3D printing can minimize mold waste while allowing intricate forms to be fabricated. In this research, we explore the use of waste cardboard as a substrate for cultivating mycelium-based composites and the development of extrudable mixtures and workflows for 3D-printing mycelium-based components. In this paper, existing research on the use of mycelium-based material in recent 3D printing efforts was reviewed. This review is followed by the MycoPrint experiments that we conducted, and we focus on the main challenges that we faced (i.e., contamination) and the ways in which we addressed them. The results of this research demonstrate the feasibility of using waste cardboard as a substrate for cultivating mycelia and the potential for developing extrudable mixtures and workflows for 3D-printing mycelium-based components.

3D Bioprinting of Food Grade Hydrogel Infused with Living Pleurotus ostreatus Mycelium in Non-sterile Conditions

“…Contamination is often considered detrimental in the production of functional mycelium objects due to competition from other microorganisms. Mohseni et al described contamination as the main challenge in their 3D bioprinting efforts with living mycelium . However, new evidence suggests that contamination may not be a major concern.…”

“…Mohseni et al described contamination as the main challenge in their 3D bioprinting efforts with living mycelium. 4 However, new evidence suggests that contamination may not be a major concern. McBee et al used nonsterile feedstocks with pre-existing communities of bacterial contaminants and found that G. mycelium still propagated throughout the feedstock to successfully produce mycelium biocomposites.…”

“…Fungal mycelium consists of interwoven filamentous cells called hyphae that form ramified adaptive networks involved in nutrient acquisition and transport, cell–cell communication, and cross-feeding interactions. , Over the past two decades, biofabrication with mycelium has gained considerable interest from academic researchers and industry for the production of environmentally friendly alternatives to conventional plastic materials such as expanded polystyrene foams, which are energy- and carbon-intensive to manufacture . Functional materials prepared with the first generation of mycelium technologies are often referred to as mycelium-based composites or mycelium biocomposites. , Generally, mycelium biocomposites are produced by mixing a fungal inoculum with a sterilized lignocellulosic substrate (such as sawdust), packing this mixture into a template, and maintaining the assembly under specific environmental conditions optimized for growth. Over 1–2 weeks, the mycelium proliferates throughout the substrate, eventually binding the substrate together into a singular object conforming to the template shape.…”

“…3 Functional materials prepared with the first generation of mycelium technologies are often referred to as mycelium-based composites or mycelium biocomposites. 4,5 Generally, mycelium biocomposites are produced by mixing a fungal inoculum with a sterilized lignocellulosic substrate (such as sawdust), packing this mixture into a template, and maintaining the assembly under specific environmental conditions optimized for growth. Over 1−2 weeks, the mycelium proliferates throughout the substrate, eventually binding the substrate together into a singular object conforming to the template shape.…”

“…12 Pleurotus ostreatus (oyster mushroom) mycelium is among the strains most commonly used in mycelium biofabrication. 13 However, studies that have demonstrated 3D bioprinting with P. ostreatus mycelium have largely focused on scale-up of the bioprinting process and in doing so have incorporated low-cost bulking agents such as cardboard 4 and food waste 14 into the hydrogel formulation. These solid additives are not suitable for certain applications.…”