Valorisation of spent cultivated meat media for recombinant FGF2 production in GRAS Lactococcus lactis

Innovative strategies for sustainable utilization of waste resources are imperative in the pursuit of a circular economy. Recently, the idea of utilizing mammalian spent media as a valuable resource is gaining traction, offering significant opportunities for innovative uses as a food-grade feedstock for microbial fermentation, especially in the production of alternative proteins for research and food purposes. In this study, we aim to repurpose spent mammalian culture media for production of valuable proteins. Growth factors (GFs) are a family of high-value proteins that naturally stimulate cell proliferation or differentiation. More importantly, these factors also present significant costs for cell culture. Here, we successfully demonstrate the use of spent mammalian culture media for the recombinant production of fibroblast growth factor 2 (FGF2-G3) in Lactococcus lactis. Bioreactor fermentation at a 1 L scale confirmed purified yields of 2.6 mg/L of recombinant FGF2-G3 using spent media. Further functional testing indicated that the recombinant FGF2-G3 can promote cell proliferation on an Anguilla japonica (Japanese eel) pre-adipocytic cell line, suggesting its potential for cultivated meat production. Based on the preliminary results of this study, our calculations indicate that fermenting 1 L spent mammalian waste could yield enough growth factors to efficiently grow approximately 52 L of cultivated meat through fermentation. This prediction emphasizes the potential of waste valorisation to sustainably produce protein, thus contributing to environmental preservation and economic viability. HighlightsO_LISpent mammalian culture media can be repurposed for microbial fermentation. C_LIO_LIGRAS L. lactis was used to express FGF2-G3 in an optimized spent media formulation. C_LIO_LIFunctional FGF2-G3 expression was demonstrated in controlled 1-L bioreactor runs. C_LI