The impact of magnesium sulfate supplementation and growth duration on the properties of mycelium-based composites and chitin expression

Abstract

Mycelium-based composites (MBCs) are eco-friendly renewable alternatives to fossil-fuel based foams and composites, bringing forward resource efficiency, biodegradability, carbon sequestration, and green bioengineering. Produced from agricultural waste and fungal mycelium, the physical and mechanical properties of MBCs vary depending on the growth conditions of material production, after the choice of the substrate and fungal species. The tunability of the key properties of hemp-hurds based MBCs was investigated by varying growth time and supplementation with MgSO4 using Ganoderma lucidum and Trametes pubescens. The properties of the MBCs were investigated through unconfined compression force deflection, Fourier transform infrared (FTIR) spectroscopy, transient thermal conductivity measurement, and various measurements of physical characteristics. Compressive strength at 10% strain ranged between 43.11-73.23 kPa, with the highest strength belonging to the G. lucidum magnesium supplemented short-cultivation treatment. The thermal conductivity of the samples differed minimally within the 0.0495 to 0.055 W.m-1.K-1 range. FTIR analysis suggested that MgSO4 supplementation may increase mycelial chitin content in a species-dependent manner. Overall, T. pubescens produced composites with lower density and Young’s modulus but higher water absorption rate (WAR), characteristics that may be advantageous for certain packaging applications. G. lucidum delivers a biocomposite with higher compressive strength and low WAR, ideal for applications in the construction industry.