The potential of mycelium from mushroom-producing fungi in alternative protein production: a focus on fungal growth, metabolism, and nutrition

The growing need for high-quality protein with minimal environmental impact necessitates the expansion of alternative proteins on the market. One area with great opportunity for expansion lies in the phylogenetic diversity of the fungal kingdom. Diversifying the use of fungal species, by assessing species from the phylum of mushroom-producing fungi (Basidiomycota) in solid-state fermentation, could open new avenues to foods with improved nutritional and sensorial properties. To assess these properties, we first determined the potential of basidiomycetes to ferment and colonize cereals and legumes. A phylogenetically diverse selection of eight species of basidiomycetes was analyzed on their radial growth speed and biomass yield. The best performing species were successfully fermented on brown rice (high starch), brewers spent grain (high fiber, high protein), and lupin (high protein, high fiber and high fat), and compared to Rhizopus microsporus var. oligosporus. Large variation in performance was observed between the different basidiomycetes on the three substrates in terms of biomass formation and metabolic behavior. The presence of an easily accessible carbon source, such as starch was needed to prevent deamination and thereby loss of valuable protein. With the correct formulation, basidiomycetes could fully ferment and colonize the substrate, thereby increasing the overall protein content and degrading the anti-nutritional factor phytic acid up to 80%. These results provide a methodology for screening of fungal species and substrates and demonstrate that basidiomycetous mycelia represent a promising source of phylogenetic diversity for novel food fermentations.