Metabolic Engineering of Microbial Cell Factories for Efficient Heme Biosynthesis: Advances, Challenges, and Future Perspectives

, for efficient heme biosynthesis. While biosynthetic titers have improved significantly through modular optimization and excretion engineering, heme's stability and functional mechanisms under industrial food processing conditions remain unsystematically reviewed. In this work, we also emphasize the thermomechanical fate and catalytic role of microbial heme during food processing. We analyze how biochemical pathway diversity (PPD, CPD, and SHD routes) informs host-specific engineering strategies while examining heme's stability and its role in oxidative cross-linking of proteins under extreme heat and high shear. This review provides a comprehensive framework for engineering next-generation, high-performance sustainable foods.