Multiple enzymes involved in hydrogen metabolism have been detected in photosynthetic bacterium Rhodospirillum rubrum un-der various growth conditions.To investigate hydrogen metabolic pathways and the contribution of...Multiple enzymes involved in hydrogen metabolism have been detected in photosynthetic bacterium Rhodospirillum rubrum un-der various growth conditions.To investigate hydrogen metabolic pathways and the contribution of each pathway to hydrogen photoproduction in R.rubrum under the artificial illumination condition,three mutants were constructed,including nifHanfDG double mutant lacking both Fe-nitrogenase and Mo-nitrogenase,anfDG mutant lacking Fe-nitrogenase and nifHhupL double mu-tant(uptake hydrogenase deficient mutant).Comparison of the hydrogen production of these 3 mutants with R.rubrum wild type and the uptake hydrogenase deficient mutant showed that there was a third pathway involved in hydrogen production besides Mo-nitrogenase and Fe-nitrogenase,which mainly contributed to hydrogen evolution.Only a small portion of hydrogen was gen-erated by the third pathway.The hydrogen produced by Mo-nitrogenase,Fe-nitrogenase and the third pathway was about 93.5%,4.9%and 1.5%,respectively,while the hydrogen consumed by uptake hydrogenase was about 13.3%.The investigation of the formate-linked hydrogenase activity indicated that the third pathway for hydrogen production was not mediated by the for-mate-linked hydrogenase,but probably by some unknown enzyme.展开更多
基金supported by the National High Technology Research and Development Program of China(Grant No 2006AA05z108)
文摘Multiple enzymes involved in hydrogen metabolism have been detected in photosynthetic bacterium Rhodospirillum rubrum un-der various growth conditions.To investigate hydrogen metabolic pathways and the contribution of each pathway to hydrogen photoproduction in R.rubrum under the artificial illumination condition,three mutants were constructed,including nifHanfDG double mutant lacking both Fe-nitrogenase and Mo-nitrogenase,anfDG mutant lacking Fe-nitrogenase and nifHhupL double mu-tant(uptake hydrogenase deficient mutant).Comparison of the hydrogen production of these 3 mutants with R.rubrum wild type and the uptake hydrogenase deficient mutant showed that there was a third pathway involved in hydrogen production besides Mo-nitrogenase and Fe-nitrogenase,which mainly contributed to hydrogen evolution.Only a small portion of hydrogen was gen-erated by the third pathway.The hydrogen produced by Mo-nitrogenase,Fe-nitrogenase and the third pathway was about 93.5%,4.9%and 1.5%,respectively,while the hydrogen consumed by uptake hydrogenase was about 13.3%.The investigation of the formate-linked hydrogenase activity indicated that the third pathway for hydrogen production was not mediated by the for-mate-linked hydrogenase,but probably by some unknown enzyme.
