A PSII reaction center complex consisting of three polypeptides, D_1, D_2 and Cyt. b_(559), was first purified from broad bean leaves. The complex was fairly active inDCIP photoreduction in the presence of DPC, and sh...A PSII reaction center complex consisting of three polypeptides, D_1, D_2 and Cyt. b_(559), was first purified from broad bean leaves. The complex was fairly active inDCIP photoreduction in the presence of DPC, and showed signal Ⅱs either in the dark or under illumination. The complex also contained manganese atoms. Its Mn^(2+)-EPR intensity decreased by about 40% under continuous illumination and recovered to the original level when the complex was transferred to the dark. The above results indicated that the complex reported here contains all of the PSII electron transport chain components from the secondary donor Z to the stable primary electron acceptor Q_A, and it is possible that the complex contains manganese binding sites. The alternation in dark and illumination can induce reversible valence changes of the manganese atoms in the purified complex.展开更多
The salt-tolerant Staphylococcus cohnii strain, isolated from textile wastewater, has been found effective on decolorizing several kinds of azo dyes with different structures. The optimal conditions for azo dye acid r...The salt-tolerant Staphylococcus cohnii strain, isolated from textile wastewater, has been found effective on decolorizing several kinds of azo dyes with different structures. The optimal conditions for azo dye acid red B （ARB） decolorization by S. cohnii were determined to be pH= 7.0 and 30℃. The decolorization efficiency increased with the increase of the salinity concentration, and around 90% of ARB （100mg.L-1） could be decolorized in 24 h when the salinity concentration was up to 50 g-L 1. Moreover, the strain could still decolorize 19% of ARB in 24 h even when the NaC1 concentration was increased to 150 g. L1. Meanwhile, the dependence of the specific decolorization rate by S. cohnii on the ARB concentration could be described with Michaelis-Menten kinetics （Kin = 585.7mg·L-1, Vmax = t09.8mg-g cell ·h ^-1）. The addition of quinone redox mediator, named 2-hydroxy-l,4-naphthoquinone and anthraqui- none-2,6-disulfonate, significantly accelerated the deco- lorization performance ofS. cohnii. Furtherly, the activities of azoreductase （0.55 μmol.mg protein^-1.min-1） and Nicotineamide adenine dinucleotide-dichlorophenol indophenol （NADH-DCIP） reductase （8.9μmol.mg proteinl.min-1） have been observed in the crude cell extracts of S. cohnii. The decolorization products of ARB were analyzed by HPLC-MS, and the results indicated the reductive pathway was responsible for azo dye decoloriza- tion by S. cohnii.展开更多
基金Project supported by the National Natural Science Foundation of China
文摘A PSII reaction center complex consisting of three polypeptides, D_1, D_2 and Cyt. b_(559), was first purified from broad bean leaves. The complex was fairly active inDCIP photoreduction in the presence of DPC, and showed signal Ⅱs either in the dark or under illumination. The complex also contained manganese atoms. Its Mn^(2+)-EPR intensity decreased by about 40% under continuous illumination and recovered to the original level when the complex was transferred to the dark. The above results indicated that the complex reported here contains all of the PSII electron transport chain components from the secondary donor Z to the stable primary electron acceptor Q_A, and it is possible that the complex contains manganese binding sites. The alternation in dark and illumination can induce reversible valence changes of the manganese atoms in the purified complex.
文摘The salt-tolerant Staphylococcus cohnii strain, isolated from textile wastewater, has been found effective on decolorizing several kinds of azo dyes with different structures. The optimal conditions for azo dye acid red B （ARB） decolorization by S. cohnii were determined to be pH= 7.0 and 30℃. The decolorization efficiency increased with the increase of the salinity concentration, and around 90% of ARB （100mg.L-1） could be decolorized in 24 h when the salinity concentration was up to 50 g-L 1. Moreover, the strain could still decolorize 19% of ARB in 24 h even when the NaC1 concentration was increased to 150 g. L1. Meanwhile, the dependence of the specific decolorization rate by S. cohnii on the ARB concentration could be described with Michaelis-Menten kinetics （Kin = 585.7mg·L-1, Vmax = t09.8mg-g cell ·h ^-1）. The addition of quinone redox mediator, named 2-hydroxy-l,4-naphthoquinone and anthraqui- none-2,6-disulfonate, significantly accelerated the deco- lorization performance ofS. cohnii. Furtherly, the activities of azoreductase （0.55 μmol.mg protein^-1.min-1） and Nicotineamide adenine dinucleotide-dichlorophenol indophenol （NADH-DCIP） reductase （8.9μmol.mg proteinl.min-1） have been observed in the crude cell extracts of S. cohnii. The decolorization products of ARB were analyzed by HPLC-MS, and the results indicated the reductive pathway was responsible for azo dye decoloriza- tion by S. cohnii.
