Engineering nonphotosynthetic carbon fixation for production of bioplastics by methanogenic archaea

Significance Biological carbon fixation provides opportunities to directly utilize CO 2 to synthesize a broad range of value-added compounds, potentially displacing petroleum feedstock use in industry. Chemoautotrophs are particularly interesting as their carbon fixation can be driven chemically by renewable H 2 in place of light, which can limit industrial fermentation of photosynthetic organisms. We describe the development of a methanogenic host, Methanococcus maripaludis , for metabolic engineering. Since redox cofactors used in upstream archaeal carbon fixation pathways are orthogonal to typical downstream biosynthetic pathways, it was necessary to engineer both NADH biosynthesis and turnover. In doing so, we are able to show that methanogenic archaea can, indeed, serve as a platform for the high-yield production of bioplastics and monomers from CO 2 and H 2 .