One new triterpcnoid saponin, quinquenoside L17 （1）, was isolated from the leaves and stems of Panax quinquefolium L., and its structure was elucidated as 20-O-[（β-D-xylopyranosyl-（1-6）-O-β-D-glucopyranosy）]-6...One new triterpcnoid saponin, quinquenoside L17 （1）, was isolated from the leaves and stems of Panax quinquefolium L., and its structure was elucidated as 20-O-[（β-D-xylopyranosyl-（1-6）-O-β-D-glucopyranosy）]-6-O-β-D-glucopyranosy1-dammar-24-ene- 3,6,12,20-tetraol, by the combination analysis of one-dimensional NMR and two-dimensional NMR, mass spectrometry, CD spectrum and chemical evidences.展开更多
In microbial fuel cell (MFC), the rate of electron transfer to anode electrode is a key intrinsic limiting factor on the power output of MFCs. Using Klebsiella pneumoniae (K. pneumoniae) strain L17 as biocatalyst, we ...In microbial fuel cell (MFC), the rate of electron transfer to anode electrode is a key intrinsic limiting factor on the power output of MFCs. Using Klebsiella pneumoniae (K. pneumoniae) strain L17 as biocatalyst, we studied the mechanism of electron shuttle via self-producing mediator in a cubic air-chamber MFC. To eliminate the influence of biofilm mechanism, the anode electrode was coated with microfiltration membrane (0.22 μm). Data showed that the microfiltration membrane coated and uncoated MFCs achieved the maximum voltage outputs of 316.2 and 426.2 mV after 270 and 120 h, respectively. When the medium was replaced in MFCs that had the highest power generation, the power output dropped by 62.1% and 8.8%, and required 120 and 48 h to resume the original level in the coated and uncoated MFCs, respectively. The results suggested an electron-shuttle mechanism rather than biofilm mechanism was responsible for electricity generation in the membrane coated MFC. Cyclic voltammetric measurements demonstrated the presence of an electrochemical active compound produced by K. pneumoniae strain L17, which was identified to be 2,6-di-tert-butyl-p-benzoquinon (2,6-DTBBQ) by GC-MS. 2,6-DTBBQ, as a recyclable electron shuttle, could transfer electrons between K. pneumoniae L17 and the anode electrode.展开更多
基金supported by 973 Program(No.2006CB708517)Program for New Century Excellent Talents in University of Peoples Republic of China(No.NCET-04-0289)
文摘One new triterpcnoid saponin, quinquenoside L17 （1）, was isolated from the leaves and stems of Panax quinquefolium L., and its structure was elucidated as 20-O-[（β-D-xylopyranosyl-（1-6）-O-β-D-glucopyranosy）]-6-O-β-D-glucopyranosy1-dammar-24-ene- 3,6,12,20-tetraol, by the combination analysis of one-dimensional NMR and two-dimensional NMR, mass spectrometry, CD spectrum and chemical evidences.
基金supported by the National Natural Science Foundation of China (No 20777013)Natural Science Foundation of Guangdong Province, China (No 07006759)The Sci & Tech Innovation project of Guangdong Academy of Sciences, China (Gtard No CX200704)
文摘In microbial fuel cell (MFC), the rate of electron transfer to anode electrode is a key intrinsic limiting factor on the power output of MFCs. Using Klebsiella pneumoniae (K. pneumoniae) strain L17 as biocatalyst, we studied the mechanism of electron shuttle via self-producing mediator in a cubic air-chamber MFC. To eliminate the influence of biofilm mechanism, the anode electrode was coated with microfiltration membrane (0.22 μm). Data showed that the microfiltration membrane coated and uncoated MFCs achieved the maximum voltage outputs of 316.2 and 426.2 mV after 270 and 120 h, respectively. When the medium was replaced in MFCs that had the highest power generation, the power output dropped by 62.1% and 8.8%, and required 120 and 48 h to resume the original level in the coated and uncoated MFCs, respectively. The results suggested an electron-shuttle mechanism rather than biofilm mechanism was responsible for electricity generation in the membrane coated MFC. Cyclic voltammetric measurements demonstrated the presence of an electrochemical active compound produced by K. pneumoniae strain L17, which was identified to be 2,6-di-tert-butyl-p-benzoquinon (2,6-DTBBQ) by GC-MS. 2,6-DTBBQ, as a recyclable electron shuttle, could transfer electrons between K. pneumoniae L17 and the anode electrode.
