Microbial Production of Alternative Proteins for Food Applications: Advances, Industrial Challenges, and Regulatory Status.

The escalating global population and the environmentally inefficient nature of livestock-based protein production are intensifying demand for sustainable and scalable protein alternatives. Microbial biosynthesis, employing engineered cell factories, represents a pivotal strategy for producing functional proteins with a reduced ecological footprint. This review comprehensively examines the biosynthesis of alternative proteins (APs) via microbial precision fermentation, encompassing diverse categories including coloring proteins, flavoring and taste proteins, structuring and texturizing proteins, nutritional and functional proteins, food processing and enabling proteins, and special functional proteins. Enabling technologies, from fermentation feedstock and microbial host selection to genome/metabolic engineering, bioprocess optimization via response surface methodology/artificial neural networks, and downstream purification, are critically analyzed. Emerging strategies demonstrate substantial progress in enhancing microbial titers, achieving functional mimicry, and advancing regulatory readiness. However, persistent challenges include precise flavor replication, nutritional completeness, and food safety concerns such as allergenicity and process contaminants. Potential solutions, including advanced metabolic engineering, refined protein extraction, biocontainment strategies, and transparent regulatory frameworks, are discussed. By integrating technological innovation with targeted application mapping and regulatory foresight, this review outlines a roadmap toward scalable, safe, and functionally robust microbial AP platforms, thereby contributing to the transition toward a sustainable food system.