Fig. 1

Scheme of E. coli-based synthetic formatotrophic strain development. The formate assimilation pathways were constructed in E. coli and adaptive laboratory evolution was carried out with 150 serial subcultures. The red arrows indicate engineered pathways and the black arrows indicate innate pathways. THF, tetrahydrofolate; N¹⁰-fTHF, 10-formyl tetrahydrofolate; 5,10-CH⁺-THF, 5,10-methenyl tetrahydrofolate; 5,10-CH₂-THF, 5,10-methylene tetrahydrofolate; 2PGA, 2-phosphoglycerate; PEP, phosphoenolpyruvate; Pyr, pyruvate; OAA, oxaloacetate; FtfL, formate-tetrahydrofolate ligase; Fch, methenyl tetrahydrofolate cyclohydrolase; MtdA, methylene-tetrahydrofolate dehydrogenase; GlyA, serine hydroxymethyltransferase; Sga, serine-glyoxylate transaminase; Hpr, hydroxypyruvate reductase; Gck, glycerate kinase