The effect of pH of the fermentation medium on cell growth and the production of a novel bioflocculant(named REA-11) by Corynebacterium glutamicum CCTCC M201005 were investigated. The maximum biomass(2.23 g/L) and fl...The effect of pH of the fermentation medium on cell growth and the production of a novel bioflocculant(named REA-11) by Corynebacterium glutamicum CCTCC M201005 were investigated. The maximum biomass(2.23 g/L) and flocculating activity(142.2 U/mL) were simultaneously obtained at the 14th hour when the pH value of the culture medium was maintained at 7.0 during the whole fermentation process. The production of REA-11 kept on a trend of increase till the later phase of fermentation process, which resulted in the ultimate flocculating activity of the culture broth to enhance to nearly 100 U/mL at pH 6.0. A two-stage pH control mode was adopted in REA-11 production in which the pH value of the culture medium was controlled at 7.0 during the first 14 h, then decreased to 6.0 that was maintained until the end of the fermentation process. With the two-stage pH control mode, the maximum flocculating activity reached 178.8 U/mL which was 30% higher than that obtained under the condition of pH 7.0 and the biomass enhanced about 15%. Compared with the fermentation process without pH control, REA-11 production and cell growth via the two-stage pH control mode increased 80% and 25%, respectively.展开更多
D-Glucose, L-arabinose, D-mannose, D-xylose, and cellobiose are saccharification products of lignocellulose and important carbon sources for industrial fermentation. The fermentation efficiency with each of the five s...D-Glucose, L-arabinose, D-mannose, D-xylose, and cellobiose are saccharification products of lignocellulose and important carbon sources for industrial fermentation. The fermentation efficiency with each of the five sugars and the mixture of the two most dominant sugars, D-glucose and D-xylose, was evaluated for acetone- butanol-ethanol （ABE） fermentation by Clostridium acetobutylicum ATCC 824. The utilization efficacy of the five reducing sugars was in the order of D-glucose, L-arabinose, D-mannose, o-xylose and cellobiose, o-Xylose, the second most abundant component in lignocellulosic hydrolysate, was used in the fermentation either as sole carbon source or mixed with glucose. The results indicated that maintaining pH at 4.8, the optimal pH value for solventogenesis, could increase D-xylose consumption when it was the sole carbon source. Different media con- taining D-glucose and D-xylose at different ratios （1：2, 1：5, 1.5：1, 2：1 ） were then attempted for the ABE fermenta- tion. When pH was at 4.8 and xylose concentration was five times that of glucose, a 256.9% increase in xylose utilization and 263.7% increase in solvent production were obtained compared to those without pH control. These results demonstrate a possible approach combining optimized pH control and D-glucose and D-xylose ratio to increase the fermentation efficiency of lignocellulosic hydrolysate.展开更多
By taking advantage of the separation characteristics of nonlinear gain and dynamic sector inside a Hammerstein model, a novel pole placement self tuning control scheme for nonlinear Hammerstein system was put forward...By taking advantage of the separation characteristics of nonlinear gain and dynamic sector inside a Hammerstein model, a novel pole placement self tuning control scheme for nonlinear Hammerstein system was put forward based on the linear system pole placement self tuning control algorithm. And the nonlinear Hammerstein system pole placement self tuning control(NL-PP-STC) algorithm was presented in detail. The identi fication ability of its parameter estimation algorithm of NL-PP-STC was analyzed, which was always identi fiable in closed loop. Two particular problems including the selection of poles and the on-line estimation of model parameters, which may be met in applications of NL-PP-STC to real process control, were discussed. The control simulation of a strong nonlinear p H neutralization process was carried out and good control performance was achieved.展开更多
Methods to optimize the production of gamma-aminobutyric acid （GABA） by Lactobacillus brevis CGMCC 1306 were investigated. Results indicated that cell growth was maximal at pH 5.0, while pH 4.5 was pref-erable to GA...Methods to optimize the production of gamma-aminobutyric acid （GABA） by Lactobacillus brevis CGMCC 1306 were investigated. Results indicated that cell growth was maximal at pH 5.0, while pH 4.5 was pref-erable to GABA formation. The optimal temperature for cell growth （35 °C） was lower than that for GABA forma-tion （40 °C）. In a two-stage pH and temperature control fermentation, cultures were maintained at pH 5.0 and 35 °C for 32 h, then adjusted to pH 4.5 and 40 °C, GABA production increased remarkably and reached 474.79 mmol·L-1 at 72 h, while it was 398.63 mmol·L-1 with one stage pH and temperature control process, in which cultivation con-ditions were constantly controlled at pH 5.0 and 35 °C. In order to avoid the inhibition of cell growth at higher L-monosodium glutamate （L-MSG） concentrations, the two-stage control fermentation with substrate feeding strat-egy was applied to GABA production, with 106.87 mmol （20 g） L-MSG supplemented into the shaking-flask at 32 h and 56 h post-inoculation separately. The GABA concentration reached 526.33 mmol·L-1 at 72 h with the fer-mentation volume increased by 38%. These results will provide primary data to realize large-scale production of GABA by L. brevis CGMCC 1306.展开更多
Pulp and paper industry is responsible for large discharge of highly polluted effluents, which often be treated by biological treatment process. For biological treatment system, pH is an important environmental factor...Pulp and paper industry is responsible for large discharge of highly polluted effluents, which often be treated by biological treatment process. For biological treatment system, pH is an important environmental factor that can influence the activity of microorganisms. In general, the optimal pH for aerobic processes is around neutral pH (7_7.8) and for the anaerobic process is between 6.8_7.2. The control of pH is a difficult link in the biological treatment system due to its nonlinearity and large time-delay. Aiming at the difficult point in the pH control of the biological wastewater treatment system, a mathematical model of pH control is estab-lished in the essay. On this basis, a traditional PID control and a cascade control are adopted to carry out simulation and comparison with MATLAB. The results show that the cascade control has better comprehen-sive effect in terms of response speed, stability and disturbance resistance.展开更多
大豆分离蛋白(Soybean protein isolate,SPI)对外界环境的变化极其敏感,中和工段中pH值微小的变化就会改变蛋白质的结构和功能性质。通过添加NaOH调控凝乳的pH值,利用红外光谱和内源荧光光谱分析SPI的结构及功能性质,研究发现在中性条件...大豆分离蛋白(Soybean protein isolate,SPI)对外界环境的变化极其敏感,中和工段中pH值微小的变化就会改变蛋白质的结构和功能性质。通过添加NaOH调控凝乳的pH值,利用红外光谱和内源荧光光谱分析SPI的结构及功能性质,研究发现在中性条件下SPI具有较好的起泡性,碱性条件时SPI具有较好的乳化性,当体系pH值为7时,SPI的起泡性最佳,当体系pH值为8.5时,SPI的乳化性最佳。建立了25 L大豆SPI中和工段pH值精细调控体系,利用Matlab模拟生产过程,通过动态线性与静态非线性拟合,采用模糊自适应控制结合Wiener模型调控中和罐的加碱量,当将中和罐中pH值调控为7时,调节时间为37.4 s,生产的SPI起泡性指数为57.22%,将中和罐中pH值调控为8.5时,调节时间为33.4 s,生产的SPI乳化活性指数为69.35 m^(2)/g,体系无超调量用碱。展开更多
An inclusion-interaction assembly strategy was used to construct novel pH/redox responsive core-shell micelles with hydrophobic drug as the core and hydrophilic polymer as the shell. At first, a dimer of hydrophobic d...An inclusion-interaction assembly strategy was used to construct novel pH/redox responsive core-shell micelles with hydrophobic drug as the core and hydrophilic polymer as the shell. At first, a dimer of hydrophobic drug 6-mercaptopurine and a hydrophilic β-CD grafted carboxymethyl chitosan were synthesized. Then, a novel amphiphilic inclusion complex was prepared with the dimer being partially embedded into the cavity of β-CD moiety. It self-assembled into pH/redox responsive core-shell micelles in distilled water. TEM confirmed that the micelles possessed a spherical core-shell configuration with a mean size of about 160 nm. DLS showed that the micelles were stable in aqueous solution. Their particle diameters altered with pH values as well as glutathione (GSH) concentrations and respectively attained a maximum value at pH 6.0 and 20 mM GSH. Release profiles of 6-mercaptopurine showed a low release rate (about 27 wt% after 48 h) in pH 7.4 medium with 10 μM GSH, and a marked increase (over 88 wt% after 48 h) in pH 5.0 medium with 20 mM GSH. In vitro cytotoxicity test showed that the micelles had a dose-dependent toxicity for HeLa cells, indicating a great potential for controlled release of 6-mercaptopurine in tumor cells.展开更多
基金Supported by the Innovative Project for Young Scientific Scholars of Fujian Province(No.2 0 0 2 J0 4 4 )
文摘The effect of pH of the fermentation medium on cell growth and the production of a novel bioflocculant(named REA-11) by Corynebacterium glutamicum CCTCC M201005 were investigated. The maximum biomass(2.23 g/L) and flocculating activity(142.2 U/mL) were simultaneously obtained at the 14th hour when the pH value of the culture medium was maintained at 7.0 during the whole fermentation process. The production of REA-11 kept on a trend of increase till the later phase of fermentation process, which resulted in the ultimate flocculating activity of the culture broth to enhance to nearly 100 U/mL at pH 6.0. A two-stage pH control mode was adopted in REA-11 production in which the pH value of the culture medium was controlled at 7.0 during the first 14 h, then decreased to 6.0 that was maintained until the end of the fermentation process. With the two-stage pH control mode, the maximum flocculating activity reached 178.8 U/mL which was 30% higher than that obtained under the condition of pH 7.0 and the biomass enhanced about 15%. Compared with the fermentation process without pH control, REA-11 production and cell growth via the two-stage pH control mode increased 80% and 25%, respectively.
基金Supported by the National Natural Science Foundation of China(20306026 and 21376215)the National High Technology Research and Development Program of China(2012AA022302)
文摘D-Glucose, L-arabinose, D-mannose, D-xylose, and cellobiose are saccharification products of lignocellulose and important carbon sources for industrial fermentation. The fermentation efficiency with each of the five sugars and the mixture of the two most dominant sugars, D-glucose and D-xylose, was evaluated for acetone- butanol-ethanol （ABE） fermentation by Clostridium acetobutylicum ATCC 824. The utilization efficacy of the five reducing sugars was in the order of D-glucose, L-arabinose, D-mannose, o-xylose and cellobiose, o-Xylose, the second most abundant component in lignocellulosic hydrolysate, was used in the fermentation either as sole carbon source or mixed with glucose. The results indicated that maintaining pH at 4.8, the optimal pH value for solventogenesis, could increase D-xylose consumption when it was the sole carbon source. Different media con- taining D-glucose and D-xylose at different ratios （1：2, 1：5, 1.5：1, 2：1 ） were then attempted for the ABE fermenta- tion. When pH was at 4.8 and xylose concentration was five times that of glucose, a 256.9% increase in xylose utilization and 263.7% increase in solvent production were obtained compared to those without pH control. These results demonstrate a possible approach combining optimized pH control and D-glucose and D-xylose ratio to increase the fermentation efficiency of lignocellulosic hydrolysate.
文摘By taking advantage of the separation characteristics of nonlinear gain and dynamic sector inside a Hammerstein model, a novel pole placement self tuning control scheme for nonlinear Hammerstein system was put forward based on the linear system pole placement self tuning control algorithm. And the nonlinear Hammerstein system pole placement self tuning control(NL-PP-STC) algorithm was presented in detail. The identi fication ability of its parameter estimation algorithm of NL-PP-STC was analyzed, which was always identi fiable in closed loop. Two particular problems including the selection of poles and the on-line estimation of model parameters, which may be met in applications of NL-PP-STC to real process control, were discussed. The control simulation of a strong nonlinear p H neutralization process was carried out and good control performance was achieved.
基金Supported by the National＇Naturai Science Foundation of China （30970638, 21176220 and 31240054）, Zhejiang Provincial Natural Science Foundation （Z13B06008） and the National Basic Research Program of China （2007CB714305）.
文摘Methods to optimize the production of gamma-aminobutyric acid （GABA） by Lactobacillus brevis CGMCC 1306 were investigated. Results indicated that cell growth was maximal at pH 5.0, while pH 4.5 was pref-erable to GABA formation. The optimal temperature for cell growth （35 °C） was lower than that for GABA forma-tion （40 °C）. In a two-stage pH and temperature control fermentation, cultures were maintained at pH 5.0 and 35 °C for 32 h, then adjusted to pH 4.5 and 40 °C, GABA production increased remarkably and reached 474.79 mmol·L-1 at 72 h, while it was 398.63 mmol·L-1 with one stage pH and temperature control process, in which cultivation con-ditions were constantly controlled at pH 5.0 and 35 °C. In order to avoid the inhibition of cell growth at higher L-monosodium glutamate （L-MSG） concentrations, the two-stage control fermentation with substrate feeding strat-egy was applied to GABA production, with 106.87 mmol （20 g） L-MSG supplemented into the shaking-flask at 32 h and 56 h post-inoculation separately. The GABA concentration reached 526.33 mmol·L-1 at 72 h with the fer-mentation volume increased by 38%. These results will provide primary data to realize large-scale production of GABA by L. brevis CGMCC 1306.
文摘Pulp and paper industry is responsible for large discharge of highly polluted effluents, which often be treated by biological treatment process. For biological treatment system, pH is an important environmental factor that can influence the activity of microorganisms. In general, the optimal pH for aerobic processes is around neutral pH (7_7.8) and for the anaerobic process is between 6.8_7.2. The control of pH is a difficult link in the biological treatment system due to its nonlinearity and large time-delay. Aiming at the difficult point in the pH control of the biological wastewater treatment system, a mathematical model of pH control is estab-lished in the essay. On this basis, a traditional PID control and a cascade control are adopted to carry out simulation and comparison with MATLAB. The results show that the cascade control has better comprehen-sive effect in terms of response speed, stability and disturbance resistance.
文摘An inclusion-interaction assembly strategy was used to construct novel pH/redox responsive core-shell micelles with hydrophobic drug as the core and hydrophilic polymer as the shell. At first, a dimer of hydrophobic drug 6-mercaptopurine and a hydrophilic β-CD grafted carboxymethyl chitosan were synthesized. Then, a novel amphiphilic inclusion complex was prepared with the dimer being partially embedded into the cavity of β-CD moiety. It self-assembled into pH/redox responsive core-shell micelles in distilled water. TEM confirmed that the micelles possessed a spherical core-shell configuration with a mean size of about 160 nm. DLS showed that the micelles were stable in aqueous solution. Their particle diameters altered with pH values as well as glutathione (GSH) concentrations and respectively attained a maximum value at pH 6.0 and 20 mM GSH. Release profiles of 6-mercaptopurine showed a low release rate (about 27 wt% after 48 h) in pH 7.4 medium with 10 μM GSH, and a marked increase (over 88 wt% after 48 h) in pH 5.0 medium with 20 mM GSH. In vitro cytotoxicity test showed that the micelles had a dose-dependent toxicity for HeLa cells, indicating a great potential for controlled release of 6-mercaptopurine in tumor cells.
