Fine-tuning of the flavonoid biosynthesis pathway by promoter strategies

Jingwen ZHOU 한국생물공학회 2017 한국생물공학회 학술대회 Vol.2017 No.10

Fermentation and Metabolic Pathway Optimization to De Novo Synthesize (2S)-Naringenin in Escherichia coli

( Shenghu Zhou ),( Tingting Hao ),( Jingwen Zhou ) 한국미생물 · 생명공학회 2020 Journal of microbiology and biotechnology Vol.30 No.10

Flavonoids have diverse biological functions in human health. All flavonoids contain a common 2-phenyl chromone structure (C6-C3-C6) as a scaffold. Hence, in using such a scaffold, plenty of highvalue-added flavonoids can be synthesized by chemical or biological catalyzation approaches. (2S)-Naringenin is one of the most commonly used flavonoid scaffolds. However, biosynthesizing (2S)-naringenin has been restricted not only by low production but also by the expensive precursors and inducers that are used. Herein, we established an induction-free system to de novo biosynthesize (2S)-naringenin in Escherichia coli. The tyrosine synthesis pathway was enhanced by overexpressing feedback inhibition-resistant genes (aroG^fbr and tyrA^fbr) and knocking out a repressor gene (tyrR). After optimizing the fermentation medium and conditions, we found that glycerol, glucose, fatty acids, potassium acetate, temperature, and initial pH are important for producing (2S)-naringenin. Using the optimum fermentation medium and conditions, our best strain, Nar-17LM1, could produce 588 mg/l (2S)-naringenin from glucose in a 5-L bioreactor, the highest titer reported to date in E. coli.

Improvement of Scanlan’s Nonlinear Model based on Residual Analysis

Jingwen Yan,Xiaoxia Tian,Qi Zhou,Yanchun Yang 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.1

Scanlan’s semi-empirical nonlinear model has been widely applied in bridge engineering because of its simplicity. However, it is based on the oscillation displacement, and thus it fails to describe the Vortex-induce Vertical Force (VIVF) on a flat closed-box bridge deck. In the study, in order to better depict VIVFs, a new improved model was proposed. First, the residual of the Vortexinduced Vertical Force (VIVF) is regular and maintains the significant quadratic relation with the VIVF reconstructed by Scanlan’s model, which means Scanlan’s model needs to be improved by adding quadratic terms. Second, an appropriate quadratic term was a dot product of dimensionless displacement and velocity, because this term has a significant linear relation with the reconstructed VIVF in the residual plot, and is independent of the other terms in Scanlan’s model. Furthermore, in lock-in range, the maximum oscillation displacement of a blunt body at different wind speeds was predicted by the proposed model. Simulation results showed that the proposed model is suitable for describing the nonlinearity of the VIVF and well fit the measured data. Due to simplicity, validity, and parameters to be easily identified, the proposed model has potential application in engineering.

Proline Enhances Torulopsis glabrata Growth during Hyperosmotic Stress

Sha Xu,Jingwen Zhou,Liming Liu,Jian Chen 한국생물공학회 2010 Biotechnology and Bioprocess Engineering Vol.15 No.2

This study investigated that the importing of compatible solute proline could enhance the growth of the yeast Torulopsis glabrata under hyperosmotic stress. Osmolarity progressively increased from 860 to 2,603mOsmol/kg by accumulation of sodium pyruvate in the culture broth, leading to a significant decrease in cell growth. When 1.0 g/L of proline as a compatible solute was added to the culture medium, it was imported and enhanced cell growth by 59.0% at 2,603 mOsmol/kg. By addition of proline during pyruvate production, the concentration,productivity, and yield of pyruvate increased 22.1, 38.4, and 14.3%, respectively. These results suggested that T. glabrata can import proline as an osmoprotectant against high osmotic stress, thus enhance pyruvate productivity. The improvement of yeast growth and viability under hyperosmotic stress by the addition of proline provided an alternative approach to enhance the organic acids production by yeast.

Effect of MnO Content on the Interfacial Property of Mold Flux and Steel

Wanlin Wang,Jingwen Li,Lejun Zhou,Jian Yang 대한금속·재료학회 2016 METALS AND MATERIALS International Vol.22 No.4

The interfacial property between liquid mold flux and steel has significant impact on the quality of casting slab, and this property is mainly determined by the chemical composition of mold flux and the reaction between the flux and steel. The effect of MnO content on the contact angle and interfacial tension between liquid mold flux and ultra-low carbon steel was investigated by sessile drop method in this article, and the results suggested that both the contact angle and interfacial tension decreased with the increase of MnO content in the mold flux. The increase of Si and Mn and the reduction of Al and Ti in the interaction layer were caused by the chemical reactions occurred in the vicinity of interface between mold flux and steel substrate. Besides, the thickness of the interaction layer increased from 4 μm to 7 μm, then to 9 μm, 11 μm and 15 μm when the MnO content was added from 1 wt% to 3 wt%, then to 5 wt%, 7 wt%, and 9 wt% due to the fact that MnO can simplify the polymerized structure of the melt and improve the penetrability of molten mold flux to make the interfacial reaction easier.

A rapid and sensitive molecularly imprinted electrochemiluminescence sensor for Azithromycin determination in biological samples

Hu, Liqin,Zhou, Tingting,Feng, Jingwen,Jin, Hua,Tao, Yun,Luo, Dan,Mei, Surong,Lee, Yong-Ill Elsevier 2018 Journal of Electroanalytical Chemistry Vol.813 No.-

<P><B>Abstract</B></P> <P>Azithromycin (AZM) is a widely used macrolide antibiotic to treat infections caused by bacteria. Considering the side-effect to human health, a rapid and selective electrochemiluminescence (ECL) sensor was fabricated on the basis of molecularly imprinted polymer (MIP) modified carbon paste electrode as a recognition element. We systematically optimized the factors influencing the processes on the extraction and determination for AZM, including the amount of MIP power and paraffin oil, extraction solution, extraction time and the pH of Ru(bpy)<SUB>3</SUB> <SUP>2+</SUP> solution. Under the optimal condition, the wide linear range was observed from 1.0 × 10<SUP>−10</SUP> to 4.0 × 10<SUP>−7</SUP> mol L<SUP>−1</SUP>, and the limit of detection (LOD) was low as 2.3 × 10<SUP>−11</SUP> mol L<SUP>−1</SUP> (S/N = 3). The spiked recoveries of AZM in urine and blood samples were from 98.4% to 113.5% with RSD changing from 3.7% to 13.2%, respectively. The results of AZM determination by this proposed sensor were in accordance with that of high-performance liquid chromatography–tandem mass spectrometry method. Thus, the developed MIP-based ECL sensor will have a great potential application in rapid and sensitive determination of trace AZM in complex biological samples.</P> <P><B>Highlights</B></P> <P> <UL> <LI> ECL sensor </LI> <LI> MIP modified CP electrode </LI> <LI> Trace AZM determined in biological samples </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Antiviral genes in the Asian swamp eel Monopterus albus: comparison of tissue expression and inducible expression of six interferon regulatory factors

Qiaoqing Xu,Jin Wan,Tingshuang Pan,Jingwen Zhou,Kete Ai,Daiqin Yang 한국유전학회 2015 Genes & Genomics Vol.37 No.5

Interferon regulatory factors (IRFs) play a vital role in the innate and adaptive immune system. The Asian swamp eel (Monopterus albus) is one of the most economically important freshwater fishes in China. Immunological data on the species are scare. In the present study, the expression pattern of six types of interferon regulatory factor (IRF) was studied in the Asian swamp eel. Six IRFs except IRF4 were shown to be constitutively expressed in all tissues examined. Their transcription was significantly higher in lymphoid tissues, such as intestine, skin and spleen. Furthermore, IRF1 and IRF5 was also respectively expressed at a high level in the heart and brain. However, the transcript level of IRF4 was low even undetected in most tissues. After polyinosinic- polycytidylic acid (poly I:C) treatment, the transcript levels of IRF1 and IRF4 increased, while those of IRF5 and IRF7 decreased at some time points. However, IRF2 and IRF10 did not respond to the poly I:C challenge. In addition, infection with bacterial pathogen Aermonas hydrophila and an acanthocephalan could upregulate the IRFs’ expression. The results suggested that IRFs are related to the immune response to viral, bacterial and parasitic infection in Asian swamp eel, which will help to clarify the biological function of IRFs in the immune system.