Photosynthetically produced hydrogen is an attractive, sustainable fuel. Semiartificial in vitro techniques have been successfully implemented in which hydrogenases were attached to isolated photosystems for hydrogen production. However, in vitro systems are in general short lived as metabolic processes that support self-repair and maintenance are missing. So far, photosystem–hydrogenase fusions have been tested in vitro only. Here, we report photosynthetic hydrogen production using a photosystem I–hydrogenase fusion in vivo. The NiFe-hydrogenase HoxYH of the cyanobacterium Synechocstis sp. PCC 6803 was fused to its photosystem I subunit PsaD in close proximity to the 4Fe4S cluster F_B, which ordinarily donates electrons to ferredoxin. The resultant psaD-hoxYH mutant grows photoautotrophically, achieves a high concentration of photosynthetically produced hydrogen of 500 μM under anaerobic conditions in the light and does not take up the generated hydrogen. Our data indicate that photosynthetic hydrogen production in psaD-hoxYH is most likely based on both oxygenic and anoxygenic photosynthesis.

光合作用产生的氢是一种有吸引力的，可持续的燃料。半人工体外技术已成功实施，其中将氢酶连接到分离的光系统以产生氢。然而，由于缺少支持自我修复和维持的代谢过程，体外系统通常寿命很短。到目前为止，光系统-氢酶融合体仅在体外进行过测试。在这里，我们报道了使用光系统I-氢化酶融合体内的光合氢生产。蓝藻Synechocostis sp。的NiFe-氢酶HoxYH 。PCC 6803与它的光系统I亚基PsaD紧密融合，并靠近4Fe4S簇F _B，后者通常向铁氧还蛋白提供电子。所得的psaD-hoxYH突变体以光养方式生长，在厌氧条件下，在光下可达到500μM的光合作用产生的氢的高浓度，并且不吸收产生的氢。我们的数据表明，psaD-hoxYH中光合氢的产生最有可能是基于有氧和无氧光合作用。