Abstract
Previous studies in our laboratory indicated that disruption of uptake hydrogenase gene (hup) in Anabaena sp. PCC 7120 greatly improved photobiological hydrogen production (4-7 times that of wild-type) and that disruption of bi-directional hydrogenase gene did not improved the production. To see if disruption of hydrogenase genes increases hydrogen productivity in other cyanobacteria also, we have chosen Nostoc sp. PCC 7422 because it was one of the highest hydrogen producing strains among 15 N2-fixing heterocystous cyanobacteria and its Hox activity was low. We have determined the nucleotide sequence of hupSL by cloning and sequencing, and disrupted the hupL gene by homologous recombination. The Δ hupL produced H2 more than 10 times that of wild-type and at a rate of 50-70 μmoles H2 (mg Chl) -1 hr-1. These results indicate that disruption of hup gene is effective for improving hydrogen productivity in nitrogenase-based hydrogen production.
