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
As molecular weight controls the biological activities of polysaccharides, screening the optimal molecular weight of polysaccharides is important in drug research and application. In this study, hydrogen peroxide was ...As molecular weight controls the biological activities of polysaccharides, screening the optimal molecular weight of polysaccharides is important in drug research and application. In this study, hydrogen peroxide was employed as oxidant, and temperature, reaction time, and concentration of polysaccharides and hydrogen peroxide were examined for their effects on the preparation of polysaccharides in different molecular weights from Ulva pertusa. Our experiment suggested that the optimal degradation concentrations for polysac-charides and hydrogen peroxide were 2.5% (w/v) and 8.0% (v/v), respectively. The range of degradation measured by relative viscosity was mainly controlled by temperature and time. Results revealed that 35℃ was the optimal temperature for obtaining low-degradation samples, and 50℃ was the most favorable temperature to accelerate the reaction to yield highly-degraded samples. Four samples in different molecular weights A, B, C and D were finally prepared. The controllability was evaluated by the relative standard deviation (RSD) of relative viscosity, and the peak molecular weights and the polydispersity indexes (Mw/Mn) of molecular weights were measured by high performance gel permeation chromatography (HPGPC).展开更多
Membrane microfiltration fermentation (MMF) with cell recycling was successfully applied to the production of glucose oxidase (GOD). A plate microfiltration module was found suitable for such purpose. By feeding whole...Membrane microfiltration fermentation (MMF) with cell recycling was successfully applied to the production of glucose oxidase (GOD). A plate microfiltration module was found suitable for such purpose. By feeding whole medium in MMF, the productivity of GOD was much higher than that by feeding glucose alone. With increasing dilution rate the enzyme productivity increased and average enzyme activity decreased. The enzyme productivity of MMF under D = 0.12h-1 and 0.20h-1 were 3871 and 3945U·h-1 respectively, which was about 3 times as that of batch fermentation (BF) and the average enzyme activity was still as high as STU·mL-1 under D = 0.12h-1. The relative efficiency of MMF applied to low yield strain was higher than that applied to high yield strain.展开更多
The increasing of tapioca production nowadays effected the production of waste. The waste of tapioca industries consists of two kinds, which were liquid waste and solid waste. Further more, tapioca solid waste treatme...The increasing of tapioca production nowadays effected the production of waste. The waste of tapioca industries consists of two kinds, which were liquid waste and solid waste. Further more, tapioca solid waste treatment was ineffective. Weather solid waste produced from the extraction process still contains high concentration of starch that can be used to produce high quality product, for example, bio ethanol or other alternative energy sources. Objective of these experimental work was utilizing solid waste of tapioca industries and looking for the exactly composition of n-amylase and gluco-amylase enzymes on the hydrolysis processes of the solid waste of tapioca. The exact composition from both enzymes can be expected to increase the yield of glucose. Variables of cx-amylase enzyme for this research were 0.3% （w/w） and 0.5% （w/w） with liquefaction time were 1 hour and 1.5 hours, and variables of glucoamylase enzyme were 0.3% （w/w） and 0.5% （w/w）. To achieve these goals, the experimental work was held in laboratory scale with batch process. Firstly, tapioca solid waste was pretreated at 90 ~C and added u-amylase enzyme for 1 hour and 1.5 hours （variable of liquefaction time）. Then, substrate was cooled down to 60 ~C added with proposed variables of glucoamylase enzyme, and was analysed 24 hours after added. This experiment showed the best ratio between a-amylase and glucoamylase enzymes 0.5%：0.5% with 1 hour of liquefaction time. The highest glucose reaches 8.468% and yields 0.892 （g glucose/g starch） with starch conversion of 59.94%. KM = 0.0468 g/mL and rmax = 0.311 g/mL·h,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This work was supported by the Scientific and Technical Bureau of Shandong Province.
文摘As molecular weight controls the biological activities of polysaccharides, screening the optimal molecular weight of polysaccharides is important in drug research and application. In this study, hydrogen peroxide was employed as oxidant, and temperature, reaction time, and concentration of polysaccharides and hydrogen peroxide were examined for their effects on the preparation of polysaccharides in different molecular weights from Ulva pertusa. Our experiment suggested that the optimal degradation concentrations for polysac-charides and hydrogen peroxide were 2.5% (w/v) and 8.0% (v/v), respectively. The range of degradation measured by relative viscosity was mainly controlled by temperature and time. Results revealed that 35℃ was the optimal temperature for obtaining low-degradation samples, and 50℃ was the most favorable temperature to accelerate the reaction to yield highly-degraded samples. Four samples in different molecular weights A, B, C and D were finally prepared. The controllability was evaluated by the relative standard deviation (RSD) of relative viscosity, and the peak molecular weights and the polydispersity indexes (Mw/Mn) of molecular weights were measured by high performance gel permeation chromatography (HPGPC).
基金Supported by the National Natural Science Foundation of China(No.39170020).
文摘Membrane microfiltration fermentation (MMF) with cell recycling was successfully applied to the production of glucose oxidase (GOD). A plate microfiltration module was found suitable for such purpose. By feeding whole medium in MMF, the productivity of GOD was much higher than that by feeding glucose alone. With increasing dilution rate the enzyme productivity increased and average enzyme activity decreased. The enzyme productivity of MMF under D = 0.12h-1 and 0.20h-1 were 3871 and 3945U·h-1 respectively, which was about 3 times as that of batch fermentation (BF) and the average enzyme activity was still as high as STU·mL-1 under D = 0.12h-1. The relative efficiency of MMF applied to low yield strain was higher than that applied to high yield strain.
文摘The increasing of tapioca production nowadays effected the production of waste. The waste of tapioca industries consists of two kinds, which were liquid waste and solid waste. Further more, tapioca solid waste treatment was ineffective. Weather solid waste produced from the extraction process still contains high concentration of starch that can be used to produce high quality product, for example, bio ethanol or other alternative energy sources. Objective of these experimental work was utilizing solid waste of tapioca industries and looking for the exactly composition of n-amylase and gluco-amylase enzymes on the hydrolysis processes of the solid waste of tapioca. The exact composition from both enzymes can be expected to increase the yield of glucose. Variables of cx-amylase enzyme for this research were 0.3% （w/w） and 0.5% （w/w） with liquefaction time were 1 hour and 1.5 hours, and variables of glucoamylase enzyme were 0.3% （w/w） and 0.5% （w/w）. To achieve these goals, the experimental work was held in laboratory scale with batch process. Firstly, tapioca solid waste was pretreated at 90 ~C and added u-amylase enzyme for 1 hour and 1.5 hours （variable of liquefaction time）. Then, substrate was cooled down to 60 ~C added with proposed variables of glucoamylase enzyme, and was analysed 24 hours after added. This experiment showed the best ratio between a-amylase and glucoamylase enzymes 0.5%：0.5% with 1 hour of liquefaction time. The highest glucose reaches 8.468% and yields 0.892 （g glucose/g starch） with starch conversion of 59.94%. KM = 0.0468 g/mL and rmax = 0.311 g/mL·h,
