Trends in Customizable Single-Cell Protein Production Enabled by Synthetic Biology: Carbon-Negative Biomanufacturing and Engineered Functionalities

Global population growth intensifies pressure on conventional protein production, highlighting the need for sustainable alternatives, such as single-cell protein (SCP). While SCP is established in animal feed, its wider adoption faces challenges in feedstock sustainability, production efficiency, and scalability. This review examines how synthetic biology addresses these barriers across the SCP value chain. We trace the evolution of substrates from sugars to waste-derived streams and C1 compounds, emphasizing advances in engineered microbial C1 assimilation. Strain development has progressed from classical screening to rational design and model-driven metabolic engineering for optimized protein biosynthesis. Fermentation has shifted from conventional methods to model-based, digitally enabled precision control for robust, and scalable bioprocessing. Finally, we discuss emerging strategies for nutritional customization in human applications, including programmable sensory attributes and demographic-specific amino acid profiles, positioning SCP as a versatile protein source for sustainable feeds and nutrient-dense, sensorially accepted future foods.