The mycelium of L. sulphureus and I. hispidus was cultivated under sterile conditions in liquid nutrition medium in shake flasks. Wool was submerged in the culture broth and heated to 90 °C for 1 h. Afterwards, the yarn was washed and used for knitting this scarf.
A detailed description of the cultivation can be found here:
Bergmann, Pia, et al. “Cultivation of Inonotus hispidus in stirred tank and wave bag bioreactors to produce the natural colorant hispidin.” Fermentation 8.10 (2022): 541. https://doi.org/10.3390/fermentation8100541
Bergmann, Pia, et al. “Pilot-scale production of the natural colorant laetiporic acid, its stability and potential applications.” Fermentation 8.12 (2022): 684. https://doi.org/10.3390/fermentation8120684