The research is dedicated to the valorization of one-carbon (C1) compounds for feed applications through synthetic biology. C1-assimilating microorganisms, such as Cupriavidus necator and methylotrophs, are employed as microbial chassis. By integrating genetic engineering, enzyme engineering, and metabolic engineering, the metabolic networks of these microorganisms are systematically elucidated and optimized, while biosynthetic pathways for target products are rationally engineered. These efforts enable the development of high-performance microbial cell factories capable of efficiently converting one-carbon compounds into value-added feed ingredients and feed additives.