In vitro and in vivo coupling of Thiocapsa hydrogenase with cyanobacterial and algal electron mediators

H2 activation by the oxygen-tolerant hydrogenase from the purple sulfur bacterium Thiocapsa roseopersicina, using electron mediators of cyanobacterial and algal origin, has been demonstrated. Ferredoxins, either from the cyanobacterium Synechococcus PCC7942 or the green alga Scenedesmus obliquus, are capable of providing electrons for hydrogenase-mediated H2 evolution. The high-potential cytochrome c6 from Synechococcus PCC7942 proved to be capable of accepting electrons derived from hydrogenase-mediated H2 oxidation. In subsequent experiments, Thiocapsa hydrogenase was introduced into the cells of Synechococcus PCC7942 by electroporation, for enhanced H2 production.