Unlocking the Next-Generation Protein Expression Systems for Animal-Free Cheese Production

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The demand for dairy products is growing globally due to the rising income, increasing population, and dietary changes. Concerningly, dairy production is one of the biggest methane emitters in the world. Animal-free alternatives for dairy products have the potential to reduce pollution by offering sustainable production practices. However, while plant-based alternatives for milk have nearly reached price, taste, and convenience parity to animal-derived milk, plant-based cheese still fails to offer an adequate consumer experience.In the last 10 years, the potential use of precision fermentation -- a process where genetically modified microorganisms are used as cell factories to produce desired biomolecules, such as pharmaceuticals and biofuels -- has been investigated for food protein production. While in principle precision fermentation offers a sustainable and ethical way of producing food proteins, to date no major alternative protein company has been able to offer affordable and scalable solutions to casein -- the main cheese protein -- production.We argue that the lack of progress is mainly due to the attempts to genetically engineer conventional industrial microorganisms such as _E. coli_ and _S. cerevisiae_ that require multiple modifications to utilise cheap food sources, withstand environmental pressures in bioreactors, and produce complex proteins. Indeed, since 2014 the alternative protein sector already saw great improvements after expanding optimisation efforts to less popular but scientifically well-established species of _P. pastoris_ and _T. reesei_. We propose that even larger gains can be achieved by adopting unconventional yeast species that might be naturally more suitable for food production but currently lack the necessary genetic engineering tools.We aim to develop the next-generation microbial factories using unconventional microbial species. Our methodology will be validated in pilot-scale bioreactors evaluating the novel strains for the industrial production of casein proteins. This proof-of-principle project will serve the whole precision fermentation sector by massively expanding the choice of protein expression systems, tailored for industrial level scalability.