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Jiazhang Lian Shinghua Ding Jin Cai Danping Zhang Zhinan Xu Xiaoning Wang 《Applied microbiology and biotechnology》2009,82(3):463-470
Aquaporin Z (AqpZ), a typical orthodox aquaporin with six transmembrane domains, was expressed as a fusion protein with TrxA
in E. coli in our previous work. In the present study, three fusion partners (DsbA, GST and MBP) were employed to improve the expression
level of this channel protein in E. coli. The result showed that, compared with the expression level of TrxA-AqpZ, five- to 40-fold increase in the productivity of
AqpZ with fusion proteins was achieved by employing these different fusion partners, and MBP was the most efficient fusion
partner to increase the expression level. By using E. coli C43 (DE3)/pMAL-AqpZ, the effects of different expression conditions were investigated systematically to improve the expression
level of MBP-AqpZ in E. coli. The high productivity of MBP-AqpZ (200 mg/l) was achieved under optimized conditions. The present work provides a novel
approach to improve the expression level of membrane proteins in E. coli. 相似文献
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Fangyou Yu Ying Liu Yuanyuan Xu Yongpeng Shang Danping Lou Zhiqiang Qin Chris Parsons Wu Zhou Xiaoying Huang Yuping Li Longhua Hu Liangxing Wang 《PloS one》2013,8(12)
Panton-Valentine leukocidin (PVL; gene designation lukF/S-PV) is likely an important virulence factor for Staphylococcus aureus (S. aureus), as qualitative expression of the protein correlates with severity for specific clinical presentations, including skin and soft tissue infections (SSTIs). Development of genetic approaches for risk-assessment of patients with S. aureus infections may prove clinically useful, and whether lukF/S-PV gene expression correlates with specific clinical presentations for S. aureus has been largely unexplored. In the present study, we quantified lukS-PV mRNA among 96 S. aureus isolates to determine whether expression levels correlated with specific clinical presentations in adults and children. Expression level of lukS-PV mRNA among isolates from skin and soft tissue infections (SSTIs) was significantly greater than among isolates from blood stream infection (BSIs), and expression level of lukS-PV mRNA among BSI isolates from children was significantly greater than for BSI isolates among adults. Moreover, expression level of lukS-PV mRNA among community-acquired (CA) isolates was significantly greater than for hospital-acquired (HA) isolates. These data justify additional studies to determine the potential clinical utility for lukS-PV mRNA quantification as a predictive tool for severity of S. aureus infection. 相似文献
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Zhang H Cai J Dong J Zhang D Huang L Xu Z Cen P 《Applied microbiology and biotechnology》2011,92(2):295-303
Poly (β-l-malic acid) (PMLA) is a water-soluble polyester with many attractive properties in chemical industry and medicine development.
However, the low titer of PMLA in the available producer strains limits further industrialization efforts and restricts its
many potential applications. In order to solve this problem, a new strain with the distinguished high productivity of PMLA
was isolated from fresh plants samples. It was characterized as the candidate of Aureobasidium pullulans based on the morphology and phylogenetic analyses of the internal transcribed spacer sequences. After the optimization of
culture conditions, the highest PMLA concentration (62.27 g l−1) could be achieved in the shake flask scale. In addition, the contribution of the carbon flux to exopolysaccharide (EPS)
and PMLA could be regulated by the addition of CaCO3 in the medium. This high-level fermentation process was further scaled up in the 10 l benchtop fermentor with a high PMLA
concentration (57.2 g l−1) and productivity (0.35 g l−1 h−1), which are the highest level in all the literature. Finally, the suitable acid hydrolysis conditions of PMLA were also investigated
with regard to the production of l-malic acid, and the kinetics of PMLA acid hydrolysis was modeled to simulate the whole degradation process. The present work
paved the road to produce this multifunctional biomaterial (PMLA) at industrial scale and promised one alternative method
to produce l-malic acid in the future. 相似文献
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手性醇是合成医药、农用化学品和其他精细化学品的关键中间体。硫酸酯酶可催化水解硫酸酯键裂解形成无机硫酸盐和相应的仲醇。笔者综述了硫酸酯酶微生物来源、催化反应机制及其应用,也介绍了固定化提高催化稳定性及通过添加金属离子或有机助溶剂提高硫酸酯酶选择性的方法。 相似文献
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Parameter identification of robot manipulators is an indispensable pivotal process of achieving accurate dynamic robot models. Since these kinetic models are highly nonlinear, it is not easy to tackle the matter of identifying their parameters. To solve the difficulty effectively, we herewith present an intelligent approach, namely, a heuristic particle swarm optimization (PSO) algorithm, which we call the elitist learning strategy (ELS) and proportional integral derivative (PID) controller hybridized PSO approach (ELPIDSO). A specified PID controller is designed to improve particles’ local and global positions information together with ELS. Parameter identification of robot manipulators is conducted for performance evaluation of our proposed approach. Experimental results clearly indicate the following findings: Compared with standard PSO (SPSO) algorithm, ELPIDSO has improved a lot. It not only enhances the diversity of the swarm, but also features better search effectiveness and efficiency in solving practical optimization problems. Accordingly, ELPIDSO is superior to least squares (LS) method, genetic algorithm (GA), and SPSO algorithm in estimating the parameters of the kinetic models of robot manipulators. 相似文献