Direct and Reversible Hydrogenation of CO 2 to Formate by a Bacterial Carbon Dioxide Reductase

Making CO 2 Work for You Converting carbon dioxide (CO 2 ) to formic acid (HCOOH) is an attractive substrate for the storage and recovery of hydrogen (H 2 ) for use as fuel. Because CO 2 is relatively stable, however, its hydrogenation typically requires extreme conditions. Schuchmann and Müller (p. 1382 : see the Perspective by Pereira ) isolated a hydrogen-dependent carbon dioxide reductase from Acetobacterium woodii that is nearly 2000-fold more effective than the fastest known chemical catalysts. The process, which relies on the formation of formate as a chemical intermediate, also works well in whole-cell systems of A. woodii when certain metabolic pathways are inhibited. The enzyme, whether isolated or present in host bacteria, may lead to the design of more efficient fuel cells capable of functioning under less harsh conditions than fuel cells based on chemical reactions alone.