查找使用阿拉丁产品的科研文献

Efficient multi-enzyme system for icaritin production from naringenin with synchronous prenol utilization in Escherichia coli

Anyi Wu,Junping Zhou,Yinan Xue,Yun Liu,Jidong Shen,Xin Gao,Zhiqiang Liu,Yuguo Zheng

Icaritin (ICT) shows various pharmacological activities and is used as an anti-hepatocellular carcinoma drug. While most of the studies focused on constructing yeast chassis cells for ICT production to replace the ICT extraction of Epimedium species, an efficient multi-enzyme system was first constructed here in the prokaryote Escherichia coli , for the successful biotransformation from naringenin (NAR) and prenol to ICT. The plant-derived flavonoid 3-hydroxylase (F3H) and flavonol synthase (FLS) were screened, and then fused together with protein linkers to efficiently catalyze the conversion of NAR to kaempferol (KAE). The isopentenol utilization (IU) pathway was subsequently introduced to increase dimethylallyl diphosphate (DMAPP) supply, along with catalytic activity improvement of prenyltransferase (PT) using N -terminal truncations and active site pocket engineering. Furthermore, by screening O -methytransferases (OMT) from different sources, EpOMT 4 from Epimedium pseudowushanense was selected for the ICT production. With the combination of these strategies, 80.8 ± 3.6 mg/L ICT could be produced from NAR and prenol in the recombinant E. coli , from the original 0 % degree of conversion. The systematic engineering of multi-enzyme system for ICT biosynthesis has laid the foundation for the large-scale ICT production using the industrially important E. coli chassis cell.

Antibacterial effects and mechanisms of quercetin-β-cyclodextrin complex mediated photodynamic on Escherichia coli O157:H7

Liu Tao,Zhu Yuzhang,Wang Jiahui,Hong Xiangyu,Liu Mi,Kong Chaonan,Zhou Rui,Li Xianke,Yang Lifang

Quercetin is a natural flavonoid with antioxidant, anti-inflammatory, and antibacterial properties. This work aimed to formulate quercetin-cyclodextrin microcapsules (QT-β-CD) while examining their photodynamic antibacterial effects and underlying mechanisms in detail. Characterization of the QT-β-CD was conducted using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The bacteriostatic effects of UV-A irradiation on Escherichia coli O157:H7 ( E. coli O157:H7) were investigated. The photodynamic impact of QT-β-CD was assessed by analyzing hydrogen peroxide (H₂O₂) production. The antimicrobial activity was further elucidated through examinations of cell membrane integrity, protein damage, changes in cellular motility, biofilm formation, and extracellular polysaccharide reduction. The effect of QT-β-CD on LuxS and motA gene expression in E. coli O157:H7 was investigated by RT-qPCR. The findings demonstrated that QT-β-CD exhibited potent photodynamic properties and functioned as an efficient photosensitizer, causing substantial damage to E. coli O157:H7 cells. These results underscore the potential of quercetin as an antimicrobial agent for food preservation.

Phosphate modified zerovalent iron enhances the interfacial hydrogen bond mediated adhesion and inactivation of Escherichia coli

Yuqing Hu,Nuanqin Zhang,Xiang Zhang,Junning Zu,Sicong Ma,Linghao Yu,Chang Guo,Xiaomei Liao,Shaohui Wang,Hao Li,Hongwei Sun,Lizhi Zhang

The microbe-surface interaction plays essential roles in various natural and anthropogenic water processes, and it is of great benefit to tailor their interfacial contact. For instance, zero-valent iron (ZVI) holds great promise as an emerging disinfection agent, but its efficiency remains limited due to the insufficient ZVI-bacteria contact. Herein we modified the surface of ZVI with potassium dihydrogen phosphate (KH 2 PO 4 ) by ball milling (P-ZVI bm ) to facilitate the close adhesion and inactivation of Escherichia coli ( E. coli ). ExDLVO simulation indicated the significantly alleviated Lewis acid-base repulsion between P-ZVI bm and E. coli due to the enhanced hydrogen bonding. ATR-FTIR spectra and DFT calculation suggested that the surface phosphate moiety could form dual hydrogen bonds with the amide domain of bacterial proteins (e.g., membrane proteins, pili, flagella, etc.), significantly shortening the length of hydrogen bonds from 1.784 to 1.781 and 1.646 Å. The enhanced adhesion of E. coli on P-ZVI bm lead to more pronounced oxidative stress and inactivation of the cells. Impressively, P-ZVI bm exhibited superior bactericidal efficiency of 99.2% in batch experiments, far surpassing that of ZVI bm (33.9%, p < 0.001). As a prototype of application, the sand column packed with P-ZVI bm continuously removed E. coli to below 100 CFU/mL from simulated groundwater. This study provided an effective and facile strategy of phosphorylation to modulate the ZVI-bacterium adhesion for contact sterilization, and may shed light on the development of novel disinfection techniques, and the design of biofilm carriers for wastewater treatment, etc.

Strategies for achieving high-level and stable production of toxic Streptomyces phospholipase D in Escherichia coli

Weide Xiong,Xianhai Zeng,Shih-Hsin Ho,Xueping Ling,Liang Shen,Chuanyi Yao,Yinghua Lu

BACKGROUND Phospholipase D (PLD) has great potential in the pharmaceutical and food industries for manufacturing bioactive phospholipids. Overproduction of PLD in Escherichia coli is difficult due to its high cytotoxicity which causes plasmid instability, short-term PLD synthesis, cell lysis and PLD leakage. To address this issue, integrated optimization of PLD production in upstream and downstream processing was performed. RESULTS Effective strategies in upstream processing include the use of plasmids containing the pSC101 par region in recA − E. coli , the use of moderately strong and tightly regulated promoter P BAD , optimization of codon usage and amino acid supplementation, maintaining the best cellular state by supplementing nutrition, and saturation induction at low temperature. Using these strategies, a large amount of PLD (1.2 × 10 5 U L −1 , 81.5 mg L −1 ) was obtained in the batch culture and PLD synthesis lasted 9 h. Additionally, cell lysis did not occur –99% of the recombinant PLD remained in the periplasm. Ultimately, the PLD was purified 327-fold by a four-step downstream process comprising extraction with 10 mmol L −1 Ethylenediaminetetraacetic acid and 0.05% (w/v) sodium deoxycholate, ammonium sulfate precipitation, anion exchange and Ni 2+ -affinity chromatography. CONCLUSION This study provides the basis for large-scale production of PLD in E. coli . © 2018 Society of Chemical Industry

Oral pretreatment with Escherichia coli Nissle 1917 enhances the host's defense against influenza A virus infection

Di Wang,Longhai Yu,Qi Lu,Meiqing Han,Baikui Wang,Xianqi Peng,Min Yue,Yan Li

Influenza A viruses (IAVs) pose a significant threat to global health, causing annual epidemics and occasional pandemics with substantial morbidity and mortality. Despite the availability of vaccines and antiviral therapies, the development of novel preventive and therapeutic strategies remains a critical research focus. In this study, we evaluated the protective effects of orally administering Escherichia coli Nissle 1917 in IAV-infected mice and elucidated its mechanisms of action by analyzing cecal microbiota and plasm metabolome profiles. Oral administration of E. coli Nissle 1917 alleviated respiratory symptoms, reduced weight loss, and mitigated pathological injury in mice infected with H9N2 or H1N1 IAV. These protective effects were mediated through the modulation of gut microbiota diversity, which increased the abundance of Bacteroides and Akkermansia , correlating with elevated pipecolic acid levels and ultimately aiding in defense against IAV infection in mice. Notably, we identified that the circulating metabolic molecule pipecolic acid plays a significant role in fighting IAV infection. Our findings suggest the potential usefulness of E. coli Nissle 1917 or pipecolic acid in influenza prevention. Impact statement In our pursuit of novel or universal antiviral strategies against influenza, we found vigorous anti-influenza activity of orally administered Escherichia coli Nissle 1917 in a mouse model. The protective effects are associated with alterations in the host's gut microbiota and metabolism, as well as the modulation of cytokine expression induced by E. coli Nissle 1917 administration. Elevated levels of specific bacteria, including Bacteroides and Akkermansia , may enhance the secretion of pipecolic acid, thereby contributing to the defense against influenza virus infection. Importantly, our study underscores the potential of E. coli Nissle 1917 and pipecolic acid as promising agents for influenza prevention.

Co-biosynthesis of germacrene A, a precursor of β-elemene, and lycopene in engineered Escherichia coli

Li Meijie,Wen Qifeng,Lv Shuzhe,Yang Rumeng,Cheng Tao,Wang Zhaobao,Yang Jianming

Abstract β-Elemene is the major component of a traditional Chinese medicine ( Rhizoma Curcumae ) for cancer treatment, and plant extraction is the major methods currently. Biosynthesis of β-elemene is a promising and attractive route due to its advantages, including environmentally friendly processes, renewable resources, and sustainable development. In this research, biosynthesis of germacrene A, direct precursor of β-elemene, in Escherichia coli was successfully performed and 11.99 mg/L germacrene A was obtained. Thereafter, a cobiosynthesis system for germacrene A and lycopene, another kind of isoprenoid, was constructed. Furthermore, the cultivation conditions were optimized. The germacrene A production was increased to the highest level reported to date, 364.26 mg/L, threefold increase to the strain with only germacrene A production. The cobiosynthesis system was suggested to promote the metabolic flux for germacrene A production. This research enabled germacrene A production in E. coli , and it highlights the promoting mechanism of the cobiosynthesis system for two chemicals which are both belonging to isoprenoids. Key points • Co-production of germacrene A and lycopene in E. coli. • Promoting mechanism of cobiosynthesis of two isoprenoid compounds in E. coli. • Shake-flask production of germacrene A reached to the highest 364.26 mg/L in E. coli.

Preparation of Gallic Acid-chitosan Copolymer and Its Antibacterial Activity against Staphylococcus Aureus and Escherichia Coli

Yan Chunchao,Xiao Feng,Qiu Tong,Zhang Xueqiong,Zhan Siwen,Lu Mengli,Yang Mengjia,Zhang Juan

To synthesize three different grafting ratios of gallic acid (GA)-chitosan (CS) copolymer by a free radical mediated grafting method, which is further applied to the field of antibacterial materials, crosslinking structures of the compound GA-CS copolymer were characterized, fully indicating that gallic acid is resoundingly grafted onto chitosan. The grafting ratios of three copolymers GA-CS are 45.71% (I), 36.12% (II), and 18.96% (III) were determined by UV-Vis spectrophotometer. The minimum inhibitory concentrations of three GA-CS copolymers are 30 µg/mL against Escherichia coli and are ranged from 250 to 550 µg/mL against Staphylococcus aureus. By counting viable bacterial colonies, it can be found that antibacterial property is preferable by increasing the grafting ratio of GA-CS copolymers. Findings of investigation on aforementioned bacteria experiment indicate that the CFU/mL values of GA-CS (I, II, III) are 2.04×10 6 , 7.56×10 6 , 1.48×10 7 to Staphylococcus aureus , and 2.96×10 6 , 1.01×10 7 , 2.14×10 7 to Escherichia coli after 12 h treatment. In addition, the interaction process between GA-CS copolymer and bacteria can be observed through a transmission electron microscope. The specific manifestation is that the bacterial cell membranes are ruptured after being treated with the copolymer, which causes the cell contents to flow out, and the cell morphology is shrunk and out of shape.

Efficient production of hydroxysalidroside in Escherichia coli via enhanced glycosylation and semi-rational design of UGT85A1

Xinru Wang,Lian Wang,Qihang Chen,Ke Wang,Huijing Wang,Dong Li,Song Gao,Weizhu Zeng,Jingwen Zhou

Hydroxysalidroside is an important natural phenylethanoid glycoside with broad application prospects in the food and pharmaceutical fields. However, its low concentration in plants and complex extraction hinder its production. Despite being a promising way to synthesize hydroxysalidroside in Escherichia coli , glycosylation remains the limiting factor for its production. A de novo biosynthetic pathway for hydroxysalidroside was successfully constructed in E. coli via the screening of glycosyltransferase, overexpressing phosphoglucomutase ( pgm ) and UDP-glucose pyrophosphorylase ( galU ) to ensure a sufficient supply of UDP-glucose (UDPG). Additionally, a semi-rational design of UGT85A1 was conducted to expand the acceptor-binding pocket to eliminate steric hindrance interfering with the binding of hydroxytyrosol. The endogenous genes ushA and otsA were knocked out to further reduce the consumption of UDPG. Finally, a titer of 5837.2 mg/L was achieved in a 5 L fermenter by optimizing the feeding times of carbon sources. This laid the foundation for the subsequent biosynthesis of phenylethanoid glycosides.

Comparison of three palm tree peroxidases expressed by Escherichia coli: Uniqueness of African oil palm peroxidase

Meile Yuan,Hongwei Zhao,Qian Huang,Xianhua Liu,Yanyu Zhou,Xiaoping Diao,Qing X. Li

Palm tree peroxidase has greater catalytic activity, stability and broad application prospects in comparison with horseradish peroxidase . However, slow growth, ecological destruction and high costs prohibit isolation of native peroxidases directly from palm trees. Bioreactor production of palm tree peroxidases would therefore be preferred to overcome such production limitations. Comparison of different recombinant glycan-free palm tree peroxidases would allow understanding the criticality of total glycans to the functions and characteristics. In the present study, African oil palm tree peroxidase expressed by Escherichia coli showed similar stability and 30-100-fold greater activity than that of recombinant royal palm tree peroxidases, but both of their comprehensive indexes were superior to the commercial, native horseradish peroxidase. Recombinant Chamaerops excelsa peroxidase showed no activity possibly due to incorrect protein folding . The results confirmed that recombinant expression by E. coli is potentially an effective means to obtain a mass of palm peroxidases with high activity and stability.

The induced and intrinsic resistance of Escherichia coli to sanguinarine is mediated by AcrB efflux pump

Jian-Sheng Dai,Jian Xu,Hao-Jie Shen,Ni-Pi Chen,Bing-Qi Zhu,Zheng-Jie Xue,Hao-Han Chen,Zhi-Shan Ding,Rui Ding,Chao-Dong Qian

Development of fluorescent artificial receptors for specific recognition and rapid detection of Escherichia coli O157:H7

Qianjin Li,Rui Li,Mengdi Wang,Jinjin Wang,Tingting Wang,Yu Jin,Jianlin Li,Fenying Wang

Development of rapid, low-cost, and sensitive sensors for monitoring Escherichia coli (E. coli) O157:H7 is very necessary and urgent to ensure food safety. In this study, we developed two fluorescent artificial receptor-based sensors via a boronate affinity molecular imprinting strategy targeting E. coli O157:H7. Fluorescein- and rhodamine-grafted artificial receptors were synthesized using bacterial surface glycoproteins and lipopolysaccharides as the molecular-sized templates to create the specific imprinted cavities. The fluorescent sensors can achieve the recognition within 5 min, displaying cross-reactivity factors of 2.6–40.6 (fluorescein) and 1.5–18.4 (rhodamine), and ultra-sensitive detection limits of 7 CFU/mL (fluorescein) and 2 CFU/mL (rhodamine). The fluorescent artificial receptor-based sensors showed spiking recovery rates in the range of 81 %∼101 %, exhibiting high accuracy as the classical plate counting method (71 %∼112 %) in milk and tap water samples. This strategy establishes a universal platform for constructing high-performance fluorescent sensors for rapidly screening pathogenic bacteria in food safety.

Selective detection of Escherichia coli based on BSA/CNTs/ UIO-66-NH2 molecularly imprinted electrochemical sensors

Jiaqi Niu,Jinhui Liu,Ping Guo,Min Du,Wanqing Wu,Ziyang Zhang,Ye Ning,Dedi Zhou,Haidong Cao

As a common contaminating bacterium, Escherichia coli (E. coli) has caused severe harm in various fields such as food, healthcare, and the environment. Traditional detection methods for Escherichia coli, owing to factors like high cost and low efficiency, are unable to meet the detection requirements at the present stage. Therefore, the development of a simple, rapid, and highly efficient detection method for Escherichia coli represents an urgent issue that needs to be addressed promptly. This study focused on the development of a highly selective molecularly imprinted electrochemical sensor for E. coli. Molecularly imprinted polymers (MIPs) were prepared by electropolymerization on the surface of glassy carbon electrode using o-phenylenediamine as the functional monomer, aminated metal-organic frameworks (MOFs) and carbon nanotubes (CNTs) as the composites, and bovine serum albumin (BSA) was added into the polymer film to attenuate the non-imprinting effect. The linear range of the sensor was 10-10 7 CFU/mL and the detection limit was 5.2 CFU/mL. Good recovery rates were shown in real samples of drinking water, milk and orange juice. In addition, the good binding ability of the E. coli template molecule to the functional monomer o-phenylenediamine was verified by molecular docking and molecular dynamics (MD) simulations. This study was able to detect E. coli in 20 min, which provides a more open idea for the application of rapid detection of E. coli on-site, as well as the construction of molecularly imprinted electrochemical sensors and the analysis of the binding mechanism between template molecules and functional monomers.