Protocol for quantification of fungal biomass in fungal composite materials based on ergosterol extraction

Fungal composite materials are lignocellulosic particles and possible inorganic additives, connected by fungal hyphae. Here, we provide a protocol for extracting the cell membrane constituent ergosterol from dried fungal composite material to quantify the fungal fraction within the fungal composite material. We describe steps for preparing calibration samples and solvent-based ergosterol extraction. This protocol can be applied to quantify fungal abundance inside fungal composite material, providing the amount of fungal biomass as a novel parameter for a more in-depth material characterization.