Semisynthetic [FeFe]-hydrogenase with stable expression and H2 production capacity in a photosynthetic microbe

Abstract

Hydrogen (H 2 ) is a promising future chemical energy carrier and feedstock with several renewable production options, including electrolyzers and biological/bioinspired systems. The top H 2 producers in nature are [FeFe]-hydrogenases, high turnover metalloenzymes with a complex maturation process that can be circumvented by artificial synthetic activation. Here, we report the expression and activation of group A and D [FeFe]-hydrogenases in a photosynthetic host organism, the unicellular cyanobacterium Synechocystis PCC 6803. The hydrogenase from Solobacterium moorei (group A) facilitates high in vivo H 2 production from purely photoautotrophically generated substrates and unmistakably links to the metabolism of the photosynthetic host. Cells harboring the non-native, semisynthetic enzyme retain their H 2 production capacity for several days after synthetic activation. This work expands both the number and the diversity of [FeFe]-hydrogenases examined in a photosynthetic background and provides important insights for future investigations into the development and understanding of biological and biohybrid H 2 production systems. Artificial activation of newly discovered [FeFe]-hydrogenases expressed in cyanobacteria Stable expression and significant H 2 production under different environmental conditions Activated, semisynthetic [FeFe]-hydrogenase remains functional in vivo for several days [FeFe]-hydrogenases are hydrogen (H 2 )-producing metalloenzymes with excellent catalytic capacities. Photosynthetic cyanobacteria are promising chassis for large-scale H 2 production due to their fast growth and minimalistic substrate requirement. Wegelius et al. use artificial activation to enable sustainable in vivo H 2 production from newly discovered [FeFe]-hydrogenases expressed in a unicellular cyanobacterium.