Lignin is a natural UV-blocking material owing to its aromatic structure with numerous phenolic, ketone, and intramolecular hydrogen bonds. To produce high-performance and applicable sunscreen from lignin, various modification methods can be applied.

Among CO ₂ -fixing metabolic pathways in nature, the linear Wood–Ljungdahl pathway (WLP) in phylogenetically diverse acetate-forming acetogens comprises the most energetically efficient pathway, requires the least number of reactions, and converts CO ₂ to formate and then into acetyl-CoA. Despite two genes encoding glycine synthase being well-conserved in WLP gene clusters, the functional role of glycine synthase under autotrophic growth conditions has remained uncertain. Here, using the reconstructed genome-scale metabolic model i SL771 based on the completed genome sequence, transcriptomics, ¹³ C isotope-based metabolite-tracing experiments, biochemical assays, and heterologous expression of the pathway in another acetogen, we discovered that the WLP and the glycine synthase pathway are functionally interconnected to fix CO ₂ , subsequently converting CO ₂ into acetyl-CoA, acetyl-phosphate, and serine. Moreover, the functional cooperation of the pathways enhances CO ₂ consumption and cellular growth rates via bypassing reducing power required reactions for cellular metabolism during autotrophic growth of acetogens.