From waste to protein: feedstock selection and sustainability in bacterial single-cell protein production

Rising global food demand urges the development of sustainable alternative protein sources. Single-cell protein (SCP), derived from microbial biomass such as bacteria, offers a promising solution due to its efficient production and minimal resource requirements. Recent advances in biotechnology have enabled the conversion of various biowastes into SCP through controlled fermentation processes. However, large-scale application faces challenges related to feedstock sustainability, safety, scalability, and consumer acceptance. Economically viable production requires nutrient-rich, low-cost substrates, such as agricultural residues, food waste, and industrial byproducts. This review highlights the critical role of feedstock in determining the economic and environmental feasibility of bacterial SCP production, and explores scaling-up strategies for industrial application. Future development should prioritize a feedstock-first approach that aligns microbial metabolism with locally available resources and integrates techno-economic and life-cycle analyses, thereby preparing bacterial SCP as a key component of a circular bioeconomy that contributes to global food security. • Bacteria can metabolize different feedstocks. • Feedstock is the key determinant in SCP production. • Industries should be feedstock-driven/feedstock-first.