Harnessing Fungal Secretion Systems for Precision Fermentation of Food Proteins

Precision fermentation is emerging as an innovative platform for manufacturing high-value food proteins, relocating food production from agricultural fields to controlled bioreactors. Importantly, these proteins must preserve the precise amino acid composition and structural properties that underpin the functionality, texture, and nutritional value of their animal-derived counterparts. However, bulk food proteins are high-volume, low-value products and therefore need to be produced at scale as cheaply as possible. Currently, intracellular protein expression requires costly cell-lysis and downstream purification steps, which comprise product purity and generally result in the product not being cost-competitive with conventional agriculture. Thus, the commercial viability of lab-grown food proteins including animal-free dairy, egg, and collagen hinges on the capacity of microbial hosts, primarily yeasts and filamentous fungi, to export correctly folded proteins into the culture medium at gram-per-liter titers, in a process known as protein secretion. Yeast and fungi are ideal host organisms due to their potential for high-yield secretion and ability to reproduce many eukaryotic post-translational modifications. Accordingly, the protein secretory pathway now sits at the crucial intersection of synthetic biology, protein engineering, and bioprocess optimization. This perspective will address modifications to the secretory pathway that can improve protein secretion efficiency. Deliberate, data-driven engineering of secretion efficiency will determine whether precision-fermented proteins advance from pilot production to routine industrial manufacture. This perspective will also address the issues of cost efficiency and scalability, exploring how protein secretion can overcome these challenges to make lab-grown food a sustainable, ethical, and viable alternative to conventional food sources.