Effect of growth factors on the production of mycelium-based biofoam

Abstract

Mycelium-based biofoam has the potential to become an alternative to petroleum-polymeric based-foam by utilising fungal mycelium and lignocellulosic material as the matrix and substrate, respectively. The lignocellulosic materials, which were rice husk, sawdust, and sugarcane bagasse, which is crucial for the production of biofoam, were tested as a substrate for Pleurotus ostreatus mycelium growth during the screening procedure. Three growth factors were varied during mycelium-based biofoam production: incubation temperature, spawn loading, and moisture content. In this study, rice husk was the ideal substrate in the production of mycelium biofoam compared to other fungi. The inhibition of P. ostreatus mycelium growth at 30 °C incubation temperature was due to decay and contamination. On the other hand, by varying the growth factor of mycelium biofoam on rice husk, the optimum dry density of mycelium–biofoam was observed at 50% (w/w) moisture content (1.07 g/cm3), while the optimum compressive strength was observed at 40% (w/w) spawn loading (1.350 MPa). These results showed that varying the growth factor could influence the mechanical behaviour of the material. The morphology of the biofoam was also observed through a scanning electron microscope. Short and highly entangled tube-like structures and compact filaments forming a material were seen, responsible for the lightness characteristic of the material. The functional group of the biofoam was also determined using a Fourier transform infrared spectrophotometer. A new band of proteins and lipids was detected at 1633 cm-1 and 3280 cm-1 in the biofoam. It clearly shows the chemical nature of feeding substrate responsible for the changes of material spectra. Therefore, this study highlighted that the biodegradable mycelium biofoam of P. ostreatus using rice husk as a substrate is a promising alternative to polymeric foam.