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Yin, Dongfeng,Chu, Cang,Ding, Xueying,Gao, Jing,Zou, Hao,Gao, Shen The Polymer Society of Korea 2009 Macromolecular Research Vol.17 No.1
In order to enhance the gene delivery efficiency and decrease the cytotoxicity of polyplexes, we synthesized Solutol-g-PEI by conjugating polyethyleneimine (PEI) to Solutol (polyoxyethylene (10) stearate), and evaluated its efficiency as a possible nonviral gene carrier candidate. Structural analysis of synthesized polymer was performed by using $^1H$-NMR. Gel retardation assay, particle sizes and zeta potential measurement confirmed that the new gene carrier formed a compact complex with plasmid DNA. The complexes were smaller than 150 nm, which implicated its potential for intracellular delivery. It showed lower cytotoxicity in three different cell lines (Hela, MCF-7, and HepG2) than PEI 25 kDa. pGL3-lus was used as a reporter gene, and the transfection efficiency was in vitro measured in Hela cells. Solutol-g-PEI showed much higher transfection efficiency than unmodified PEI 25 kDa.
Mei Shen,Zhi-Qiang Liu,Yu-Guo Zheng,Yin-Chu Shen 한국생물공학회 2009 Biotechnology and Bioprocess Engineering Vol.14 No.6
The medium components of nitrilase production by Arthrobacter nitroguajacolicus ZJUTB06-99 were optimized in this study. Effects of factors such as carbon sources, nitrogen sources, and inducers on nitrilase production were investigated. Glucose, yeast extract, and ε-caprolactam were chosen as the suitable components. Moreover, experiments were carried out to fix the concentration of three factors for the zero coded level of variables in the subsequent optimization. Response surface methodology (RSM) and central composite design (CCD) were employed for further optimization. A quadratic model was found to fit the nitrilase activity and the variables. The results revealed that the optimized medium contained (%, w/v) 2.80, glucose; 0.57, yeast extract; and 0.42, ε-caprolactam. Validation experiments were carried out under the optimized conditions and nitrilase activity of 107.49 U/L was close to the predicted activity 110.82 U/L. After optimization, the nitrilase activity attained 2.86 fold of activity compared to the unoptimized conditions and the conversion of acrylonitrile was significantly improved. The strain growth curve and nitrilase activity alteration in the course of culture were tested. The cells were suitably harvested after cultured for 72~78 h The medium components of nitrilase production by Arthrobacter nitroguajacolicus ZJUTB06-99 were optimized in this study. Effects of factors such as carbon sources, nitrogen sources, and inducers on nitrilase production were investigated. Glucose, yeast extract, and ε-caprolactam were chosen as the suitable components. Moreover, experiments were carried out to fix the concentration of three factors for the zero coded level of variables in the subsequent optimization. Response surface methodology (RSM) and central composite design (CCD) were employed for further optimization. A quadratic model was found to fit the nitrilase activity and the variables. The results revealed that the optimized medium contained (%, w/v) 2.80, glucose; 0.57, yeast extract; and 0.42, ε-caprolactam. Validation experiments were carried out under the optimized conditions and nitrilase activity of 107.49 U/L was close to the predicted activity 110.82 U/L. After optimization, the nitrilase activity attained 2.86 fold of activity compared to the unoptimized conditions and the conversion of acrylonitrile was significantly improved. The strain growth curve and nitrilase activity alteration in the course of culture were tested. The cells were suitably harvested after cultured for 72~78 h
Zhong-Ce Hu,Yu-Guo Zheng,Yin-Chu Shen 한국생물공학회 2010 Biotechnology and Bioprocess Engineering Vol.15 No.4
This study investigated the effects of DO concentration on DHA fermentation and of DO-stat fed-batch fermentation using a pH control strategy, on 1,3-dihydroxyacetone (DHA) production. The results showed that DO-stat fed-batch fermentation with pH-shift control was the optimal bioprocess for DHA production. DO-stat fedbatch fermentation was carried out at 30% air saturation,and the culture pH was automatically maintained at pH 6.0during the first 20 h and then shifted to pH 5.0 until the end of the fermentation. An optimal DHA concentration of 175.9 ± 6.7 g/L, with a production yield to glycerol of 0.87 ± 0.04 g/g, was obtained at 72 h of DO-stat fed-batch fermentation at 30°C in a 15 L fermenter.
Wang, Yuan-Shan,Xu, Jian-Miao,Zheng, Ren-Chao,Zheng, Yu-Guo,Shen, Yin-Chu The Korean Society for Microbiology and Biotechnol 2008 Journal of microbiology and biotechnology Vol.18 No.12
The R-amidase production by a newly isolated strain of Delftia tsuruhatensis ZJB-05174 was optimized in this paper. Effects of factors such as carbon sources, nitrogen sources, and inducers on amidase production were investigated. The medium composition was optimized using central composite designs and response surface analysis. The optimal medium components for enhanced amidase production were found to be as follows: glucose, 8.23 g/l; yeast extract, 11.59 g/l; 2,2-(R,S)-dimethylcyclopropane carboxamide, 1.76 g/l; NaCl, 1 g/l; ${KH_2}{PO_4}$ 1 g/l; and ${K_2}{HPO_4}$ 1 g/l. A maximum enzyme production of 528.21 U/l was obtained under the optimized conditions, which was 4.7 times higher than that obtained under initial conditions.
Xiao-Long Chen,Yu-Hua Xu,Yu-Guo Zheng,Yin-Chu Shen 한국생물공학회 2010 Biotechnology and Bioprocess Engineering Vol.15 No.6
Optimization of the feeding process for tautomycin production by Streptomyces spiroverticillatus was performed using glucose and/or maleic anhydride. The feeding of glucose was based on the reducing sugar content (lower than 8 g/L) at a cultivation time of 40 h. After addition of 2% (w/v) glucose, the biomass increased from 21 to 28 g/L, and that of tautomycin from 572.06 to 837.6mg/L. Moreover, 1723.1 mg/L of tautomycin (increased by 201.21%) was obtained by feeding 0.2% (w/v) maleic anhydride solution at a pH between 4 and 7 in the broth. For the experiments in the 15 L fermentor, tautomycin content reached its highest level (1714.7 mg/L), which was 199.7% higher than that of control by feeding both glucose and maleic anhydride.