Elementary flux mode （EFM） analysis was used in the metabolic analysis of central carbon metabolism in Saccharomyces cerevisiae based on constructed cellular network. Calculated from the metabolic model, the ethanol...Elementary flux mode （EFM） analysis was used in the metabolic analysis of central carbon metabolism in Saccharomyces cerevisiae based on constructed cellular network. Calculated from the metabolic model, the ethanol-producing pathway No. 37 furthest converts the substrate into ethanol among the 78 elementary flux modes. The in silico metabolic phenotypes predicted based on this analysis fit well with the fermentation performance of the engineered strains, KAM3 and KAMll, which confirmed that EFM analysis is valid to direct the construction of Saccharomyces cerevisiae engineered strains, to increase the ethanol yield.展开更多
Zirconium doped mesoporous KIT-6 samples with different Si/Zr ratios were synthesized by the direct hydrothermal method.Various characterization techniques confirm that highly distributed ZrO_2 nanoparticles and multi...Zirconium doped mesoporous KIT-6 samples with different Si/Zr ratios were synthesized by the direct hydrothermal method.Various characterization techniques confirm that highly distributed ZrO_2 nanoparticles and multicoordinated Zr^(4+) species are incorporated in the mesoporous composites.One-pot synthesis of 5-hydroxymethylfurfura(HMF) from glucose was examined in the presence of Zr-KIT-6(20) the molar ratio of Si to Zr is 20 under aqueous system.The effects of temperature,reaction time,catalyst dosage and biphasic solvent system on the conversion of glucose and the HMF yield were investigated.It was found that the glucose conversion and the HMF yield have been improved from 54.8% to 79.0% and from 19.5% to 34.5% in the biphasic MIBK-water system,respectively.Both the acidity of Zr-KIT-6(20) and the biphasic MIBK-water system are responsible for the improved performance of glucose dehydration to HMF.展开更多
The reactions of exo-cellulase （cellobiohydrolase, CBH） and endo-cellulase （endoglucanase, EG） were investigated by analyzing the insoluble residues of microcrystalline cellulose （MCC） and filter paper cellulose...The reactions of exo-cellulase （cellobiohydrolase, CBH） and endo-cellulase （endoglucanase, EG） were investigated by analyzing the insoluble residues of microcrystalline cellulose （MCC） and filter paper cellulose （FPC） during enzymatic hydrolysis. Molecular parameters including molecular weight and its distribution, degree of polymerization, and radii of gyration were measured by size exclusion chromatography coupled with multi-angle laser light scattering. No significant change in MCC chains was found during the whole reaction period, indicating that CBH digestion follows a layer-by-layer solubilization manner. This reaction mode might be the major reason for slow enzymatic hydrolysis of cellulose. On the other hand, the degree of polymerization of FPC chains decreases rapidly in the initial reaction, indicating that EG digestion follows a random scission manner, which may create new ends for CBH easily. The slopes of the conformation plots for MCC and FPC increase gradually, indicating stronger chain stiffness of cellulose during hvdrolvsis展开更多
基金Supported by the National Natural Science Foundation of China （No.2002AA647040）
文摘Elementary flux mode （EFM） analysis was used in the metabolic analysis of central carbon metabolism in Saccharomyces cerevisiae based on constructed cellular network. Calculated from the metabolic model, the ethanol-producing pathway No. 37 furthest converts the substrate into ethanol among the 78 elementary flux modes. The in silico metabolic phenotypes predicted based on this analysis fit well with the fermentation performance of the engineered strains, KAM3 and KAMll, which confirmed that EFM analysis is valid to direct the construction of Saccharomyces cerevisiae engineered strains, to increase the ethanol yield.
基金Supported by the National Natural Science Foundation of China(21476267)the China–Japan International Cooperation Project(2013DFG50150)the Hunan Provincial Science and Technology Department Plan Project(2016TP1007)
文摘Zirconium doped mesoporous KIT-6 samples with different Si/Zr ratios were synthesized by the direct hydrothermal method.Various characterization techniques confirm that highly distributed ZrO_2 nanoparticles and multicoordinated Zr^(4+) species are incorporated in the mesoporous composites.One-pot synthesis of 5-hydroxymethylfurfura(HMF) from glucose was examined in the presence of Zr-KIT-6(20) the molar ratio of Si to Zr is 20 under aqueous system.The effects of temperature,reaction time,catalyst dosage and biphasic solvent system on the conversion of glucose and the HMF yield were investigated.It was found that the glucose conversion and the HMF yield have been improved from 54.8% to 79.0% and from 19.5% to 34.5% in the biphasic MIBK-water system,respectively.Both the acidity of Zr-KIT-6(20) and the biphasic MIBK-water system are responsible for the improved performance of glucose dehydration to HMF.
基金Supported by the National Natural Science Foundation of China （20976130 and 20806057）, National Science and Technology Pillar Program of China （2007BAD42B02）, Program for New Century Excellent Talents in University of Ministry of Education of China （No. NCET-08-0386）, and the R＆D program of Tianjin Binhai New Area （2010-BK17C004）..
文摘The reactions of exo-cellulase （cellobiohydrolase, CBH） and endo-cellulase （endoglucanase, EG） were investigated by analyzing the insoluble residues of microcrystalline cellulose （MCC） and filter paper cellulose （FPC） during enzymatic hydrolysis. Molecular parameters including molecular weight and its distribution, degree of polymerization, and radii of gyration were measured by size exclusion chromatography coupled with multi-angle laser light scattering. No significant change in MCC chains was found during the whole reaction period, indicating that CBH digestion follows a layer-by-layer solubilization manner. This reaction mode might be the major reason for slow enzymatic hydrolysis of cellulose. On the other hand, the degree of polymerization of FPC chains decreases rapidly in the initial reaction, indicating that EG digestion follows a random scission manner, which may create new ends for CBH easily. The slopes of the conformation plots for MCC and FPC increase gradually, indicating stronger chain stiffness of cellulose during hvdrolvsis
