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Wu, Si-Ying,Park, Gil-Yong,Kim, So-Hee,Hulme, John,An, Seong Soo A Dove Medical Press 2016 Drug design, development and therapy Vol.10 No.-
<P>The aim of this study was to investigate the bacteriostatic and bactericidal effects of diminazene aceturate (DA) against five strains of pathogenic bacteria and two strains of nonpathogenic bacteria. The results showed that 5 μg/mL of DA suppressed the growth of pathogenic <I>Escherichia coli</I> by as much as 77% compared with the controls. Enterohemorrhagic <I>E. coli</I> EDL933 (an <I>E. coli</I> O157:H7 strain) was the most sensitive to DA with a minimum inhibitory concentration of 20 μg/mL. Additional investigations showed that DA induced the highest level of intracellular reactive oxygen species in EDL933. A positive correlation between the reactive oxygen species levels and DA concentration was demonstrated. DA (5 μg/mL) was also a potent uncoupler, inducing a stationary phase collapse (70%–75%) in both strains of <I>E. coli</I> O157:H7. Further investigation showed that the collapse was due to the NaCl:DA ratio in the broth and was potassium ion dependent. A protease screening assay was conducted to elucidate the underlying mechanism. It was found that at neutral pH, the hydrolysis of H-Asp-pNA increased by a factor of 2–3 in the presence of DA, implying that DA causes dysregulation of the proton motive force and a decrease in cellular pH. Finally, a commercial verotoxin test showed that DA did not significantly increase toxin production in EDL933 and was a suitable antibacterial agent for Shiga-toxin-producing <I>E. coli</I>.</P>
Recent Trends in the Detection of Pathogenic Escherichia coli O157 : H7
Si-Ying Wu,John P. Hulme,안성수 한국바이오칩학회 2015 BioChip Journal Vol.9 No.3
The rapid and accurate detection of pathogenicEscherichia coli (E. coli) poses a significant healthproblem in both developed and developing countriesaround the world. Conventional microbial detectionmethods can take more than 48 hours to identify a pathogenic organism. Recently new types of nucleic acid chip based methods, microfluidic devices, signal amplification methods, immunoassays and biosensors have been developed capable of detecting very low concentrations of pathogenic E. coli in a few hours. This review examines the current limitations and recent advances in methodologies employed in the rapid detection of pathogenic E. coli O157 : H7.
Ying-Hua Liang,Ping-Zhan Si,Ting-Ting Qi,Xin-You Wang,Fei-Yang Wang,Qiong Wu,Hong-Liang Ge,Jihoon Park,Chul-Jin Choi 한국자기학회 2024 Journal of Magnetics Vol.29 No.1
Both Mn₄C (=Mn₃MnC) and Mn₃GaC have been studied previously. However, the reports on Mn<SUB>3+x</SUB>Ga<SUB>1-x</SUB>C (0 ≤ x ≤ 1) with intermediate compositions are very rare. In this work, the structure and magnetic properties of Mn<SUB>3+x</SUB>Ga<SUB>1-x</SUB>C prepared by using solid state reaction were studied systematically. High purity anti-perovskitetype Mn<SUB>3+x</SUB>Ga<SUB>1-x</SUB>C were obtained in the composition range of 0 ≤ x ≤ 0.5, above which Mn₂₃C₆ precipitates and the fraction of Mn₂₃C₆ in the samples increases with increasing x. The structural stability, lattice parameters, and room temperature saturation magnetization of ferromagnetic Mn<SUB>3+x</SUB>Ga<SUB>1-x</SUB>C (0 ≤ x ≤ 1) decreases with increasing x. The Curie temperature of Mn<SUB>3+x</SUB>Ga<SUB>1-x</SUB>C (0 ≤ x ≤ 1) increases with increasing x. Most Mn<SUB>3+x</SUB>Ga<SUB>1-x</SUB>C with varied x exhibit near-zero coercivity and zero remanent magnetization. This work indicates that the temperature coefficient of magnetization of Mn<SUB>3+x</SUB>Ga<SUB>1-x</SUB>C may be tuned by tuning the fraction of the Ga atoms.
Xiaoqing Hu,Ju Chu,Si-Liang Zhang,Ying-ping Zhuang,Xin Wu,Huaxin Chen,Zhongyuan Lv,Zhongyi Yuan 한국생물공학회 2014 Biotechnology and Bioprocess Engineering Vol.19 No.5
Pichia pastoris is a successful system forexpressing heterologous proteins and its fermentation pH isalways maintained below 7.0. However, particular proteinsare unstable under acidic conditions, such as methionineadenosyltransferase (MAT), and thus fermentation underacidic pH conditions is unsuitable because protein activityis lost owing to denaturation. Here, a strategy employingalkaline pH in the late fermentation period was developedto improve MAT production. Initially, P. pastoris KM71was transformed with the mat gene to overexpress MAT. After 72 h of in vitro incubation at different pH values, theexpressed MAT displayed highest stability at pH 8.0;however, pH 8.0 inhibited cell growth and induced cellrupture, thus affecting protein production. To balance MATstability and Pichia cell viability, different pH controlstrategies were compared. In strategy A (reference), theinduction pH was maintained at 6.0, whereas in strategy B,it was gradually elevated to 8.0 through a 25 h transitionperiod (80 ~ 105 h). MAT activity was 0.86 U/mg (twofoldhigher than the control). However, MAT content wasreduced by 50% when compared with strategy A, becauseof proteases released upon cell lysis. To improve cellviability under alkaline conditions, glycerol was added inaddition to methanol (strategy C). When compared withstrategy B, the MAT-specific activity remained nearlyconstant, whereas the expression level increased to 1.27 g/L. The alkaline pH control strategy presented herein for MATproduction represents an excellent alternative for expressingproteins that are stable only under alkaline conditions.
Algicidal activity of thiazolidinedione derivatives against harmful algal blooming species.
Kim, Yeon-Mi,Wu, Ying,Duong, Thi Uyen,Jung, Seul-Gi,Kim, Si Wouk,Cho, Hoon,Jin, Eonseon Springer-Verlag New York Inc 2012 Marine biotechnology Vol.14 No.3
<P>Thiazolidinedione (TD) derivatives exhibit algicidal activity against harmful algal blooming species such as Chattonella marina, Heterosigma akashiwo, and Cochlodinium polykrikoides, as reported previously. In this study, the efficacies and selectivities of TD derivatives were tested by analyzing the structure-activity relationships of various TD derivatives. To investigate structure-activity relationships for growth inhibition of harmful algae, we added a methylene group between the cyclohexyl ring and oxygen of 5-(3-chloro-4-hydroxybenzylidene)-TD, which decreased the inhibitory potency of compound 17. Interestingly, another addition of a methylene group significantly increased the inhibitory potency against C. polykrikoides. The addition of 1??관M compound 17 resulted in the cell rupture of harmful algae after less than 10??h incubation at 20 °C. Compound 17 was applied to both harmful and non-harmful algae and showed a drastic reduction in the efficiency of photosystem II, resulting in reduced photosynthetic oxygen evolution. Compound 17 at a 5??관M concentration destroyed all of the harmful algae, while algicidal activity against non-harmful algae did not exceed 30% of the control within the concentration range tested. In contrast, a herbicide, 3-(3,4-dichlorophenyl)-1,1-dimethylurea, tested at a 5??관M concentration, exhibited 40-70% algicidal activity relative to that of the control against both harmful and non-harmful algae. Compound 17 is a promising lead compound for the development of algicides to control harmful algal blooming species.</P>