Microalgal co-cultivation meets media recycling: A pathway to serum and amino-acid reduction in cultivated meat

With an ever-increasing global population, demand for protein production per capita will increase. Consequently, sustainable food alternatives such as cultivated meat (CM) are urgently required. However, large-scale CM cell-systems face key challenges, particularly high media costs driven by amino acids and the need for ethically-sourced growth factors. Microalgae offer promising solutions, producing high protein yields with all essential amino acids simply from light, CO 2 , nutrient-rich or spent CM media. We present a path towards a circular CM strategy. It integrates spent CM-industry media to grow Chlorella BDH-1 as a substitute-source for reduced amino acids and serum, and combines the outcome with beneficial mammalian cell-algae co-cultivation, that similarly produces algal biomass. We identified algal growth conditions for maximum protein yield and demonstrated that two recycling rounds using industry-derived spent CM media maximize microalgal biomass yield per unit volume of waste media. We obtained algal lysate, determined thermal processing as the most cost-effective and mammalian cell-beneficial approach, and identified consumed lysate components. Overall, the algal lysate could substitute for reduced serum and amino acids with some conditions even exceeding standard growth medium performance by over 2-fold. We demonstrated synergistic effects of the algal lysate with our co-cultivation. This combination compensated for a 50% reduction in standard amino acid and serum amounts while achieving a 40% cell proliferation improvement. These results illustrate the potential for substantial reduction in reliance on high-cost and resource-intensive media components, providing a strong empirical basis for future techno-economic assessments to advance cost-effective sustainable circular cell culture systems.