To investigate differences in the methyl branch of the Wood-Ljungdahl pathway between Cladapt and Clwt, we performed a second isotopic labeling experiment using C-formate and 12 C-syngas. Cladapt exhibited significantly faster growth, achieving a cell population five times greater than Clwt within four days (Figure ). Cladapt consumed ~25 mM of C-formate within two days, whereas Clwt utilized only ~15 mM over four days (Figure ), resulting in a markedly higher production of C-acetate in Cladapt (3.86 ± 0.11 mM vs. 0.66 ± 0.06 mM) (Figure ). This finding highlights Cladapt's enhanced efficiency in utilizing formate for such as growth and acetate production, reflecting optimized pathway dynamics compared to Clwt. For further discussion, see Supplementary Note 2.