We study the photo-oxidation of bacteriochlorophylls （BChls） in peripheral light harvesting complexes （LH2） from rhodobacter sphaeroides by using the steady absorption and the femtosecond pump-probe measurement, t...We study the photo-oxidation of bacteriochlorophylls （BChls） in peripheral light harvesting complexes （LH2） from rhodobacter sphaeroides by using the steady absorption and the femtosecond pump-probe measurement, to realize the detailed dynamics of LH2 in the presence of photo-oxidation. The experimental results reveal that BChl-B850 radical cations may act as an additional channel to compete with the unoxidized BChl-B850 molecules for rapidly releasing the excitation energy, while the B800→B850 energy transfer rate is almost unaffected in the oxidation process.展开更多
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 o...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
To increase H2 yield of Rhodospirillum rubrum in two-stage hydrogen production process, two deletion mutants were constructed. One is single mutant designated R. rubrum UR801 that deleted hupL gene encoding the large ...To increase H2 yield of Rhodospirillum rubrum in two-stage hydrogen production process, two deletion mutants were constructed. One is single mutant designated R. rubrum UR801 that deleted hupL gene encoding the large subunit of uptake hy- drogenase, and the other is a double mutant desig- nated R. rubrum UR805 lacked both draTGB encod- ing regulators for the activity of nitrogenase and hupL. Comparing H2 yields of two mutants with R. rubrum UR2 (wild type) and UR472 (ΔdraTGB) under differ- ent light conditions, the results showed that the H2 yield of R. rubrum UR801 under continuous light is the highest (5700 mL of H2 per liter culture), and it is 1.56, 2.24 and 2.32-fold that of R. rubrum UR2, UR472 and UR805, respectively. However, the total H2 yield of R. rubrum UR805 in two-stage hydrogen production process is the highest (4303 mL/L), and it is 1.35, 1.21 and 1.04-fold that of R. rubrum UR2, UR801 and UR472, respectively. Thus, R. rubrum UR805 might be a valuable strain to produce a large amount of hydrogen in two-stage hydrogen produc- tion process.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 10274013 and 10374020.
文摘We study the photo-oxidation of bacteriochlorophylls （BChls） in peripheral light harvesting complexes （LH2） from rhodobacter sphaeroides by using the steady absorption and the femtosecond pump-probe measurement, to realize the detailed dynamics of LH2 in the presence of photo-oxidation. The experimental results reveal that BChl-B850 radical cations may act as an additional channel to compete with the unoxidized BChl-B850 molecules for rapidly releasing the excitation energy, while the B800→B850 energy transfer rate is almost unaffected in the oxidation process.
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.
文摘To increase H2 yield of Rhodospirillum rubrum in two-stage hydrogen production process, two deletion mutants were constructed. One is single mutant designated R. rubrum UR801 that deleted hupL gene encoding the large subunit of uptake hy- drogenase, and the other is a double mutant desig- nated R. rubrum UR805 lacked both draTGB encod- ing regulators for the activity of nitrogenase and hupL. Comparing H2 yields of two mutants with R. rubrum UR2 (wild type) and UR472 (ΔdraTGB) under differ- ent light conditions, the results showed that the H2 yield of R. rubrum UR801 under continuous light is the highest (5700 mL of H2 per liter culture), and it is 1.56, 2.24 and 2.32-fold that of R. rubrum UR2, UR472 and UR805, respectively. However, the total H2 yield of R. rubrum UR805 in two-stage hydrogen production process is the highest (4303 mL/L), and it is 1.35, 1.21 and 1.04-fold that of R. rubrum UR2, UR801 and UR472, respectively. Thus, R. rubrum UR805 might be a valuable strain to produce a large amount of hydrogen in two-stage hydrogen produc- tion process.
