FOOD CHEMISTRY
·
2024
·
IF 8.5
Bolong Fang,Xin Liu,Juan Peng,Yuzhi Li,Zhiyong Gong,Weihua Lai
In this study, a type of luminescent porous coordination network-224 (PCN-224) in alkaline conditions was synthesized with the dramatic fluorescence enhancement by 20.4 times, which was explained by the fact that the decrease of Zr 4+ content in alkaline conditions resulted in the partial recovery of the electron cloud density of 4,4′,4′′,4′′′-(Porphine-5,10,15,20-tetrayl) tetrakis(benzoic acid) (TCPP). Given the large overlap between the excitation spectrum of PCN-224 and the absorption band of Ag nanoparticles (Ag NPs), the coating of the Ag layer on PCN-224 triggered the fluorescence quenching effect, which was applied to “turn off” fluorescence immunoassay for sensitive detection of Escherichia coli O157:H7 ( E. coli O157:H7) in milk. The proposed immunoassay reached a low limit of detection (LOD) of 3.3 × 10 2 CFU mL −1 , 29.7 times more sensitive than the conventional ELISA. It will provide a novel alternative strategy for sensitively detecting pathogenic bacteria in the field of food safety.
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Analytical Methods
·
2021
·Vol. 13
·期 19
·2209-2214
·
IF 2.896
Yuan Yao,Guoming Xie,Xin Zhang,Jinshan Yuan,Yulei Hou,Hui Chen
Biosensors based on nanomaterials are becoming a research hotspot for the rapid detection of pathogenic bacteria. Herein, a “turn-on” fluorescent biosensor based on a FRET system was constructed for the fast detection of a representative pathogenic microorganism, namely, E. coli, which causes most urinary tract infections. This biosensor was constructed by utilizing synthesized UCNPs as fluorescent donors with stable luminescence performance in complex biological samples and GO@Fe3O4 as a receptor with both excellent adsorption ability and fluorescence quenching ability. A specific ssDNA selected as an aptamer which could recognize E. coli was immobilized on the UCNPs to form UCNP-Apt nanoprobes. The nanoprobes were adsorbed on the surface of GO@Fe3O4 through the π-stacking interactions between aptamers and GO. In the presence of E. coli, UCNP-Apt nanoprobes detached from GO@Fe3O4 due to the specific recognition of aptamers and bacteria, resulting in obvious fluorescence recovery, and the concentration of bacteria was positively correlated with the intensity of the fluorescence signal; such a “turn-on” signal output mode ensures excellent precision. In addition, the easy magnetic separation of GO@Fe3O4 simplifies the operation process, helping the sensor detect bacteria in 30 minutes with a linear range from 103 to 107 CFU mL−1 and a limit of detection of 467 CFU mL−1. Moreover, recovery test results also showed that the sensor has clinical application potential for the rapid detection of pathogenic microorganisms in complex biological samples.
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Foods
·
2026
·Vol. 15
·期 8
·1391
·
IF 6
Luyang Zhao,Yang Song,Guoyang Xie,Hengyi Xu
Sensitive detection ofEscherichia coliO157:H7 (E. coliO157:H7) in food matrices remains an important analytical challenge. Here, a colorimetric biosensor was constructed based on a bimetal oxide nanozyme composed of Ce-Fe oxide. This biosensor achieved sensitive detection ofE. coliO157:H7. The Ce-Fe oxide synthesized on the basis of deep eutectic solvents (DESs) had the advantages of low solvent consumption and short preparation time. By regulating the two key factors of metal valence and oxygen vacancy content, the peroxidase (POD) activity of the nanozyme was significantly improved. Compared with the single-metal oxide nanozyme Fe oxide, the addition of Ce increased the Fe2+/Fe3+ratio from 0.37 to 0.49, implying a possible enhancement of electron transfer between Fe2+and Fe3+. The detection limits (LODs) of the biosensor based on Fe oxide and that based on Ce-Fe oxide were 102CFU/mL and 101CFU/mL, respectively, comparable to existing validated methods. Moreover, these two biosensors achieved satisfactory recovery rates (91–104%) and RSDs (1.2–8.8%) in the spiked lake water, juice, and lettuce samples ofE. coliO157:H7, indicating their high potential for application in spiked sample detection. In summary, the method proposed in this study for improving the POD activity of nanozymes through electron transfer in DES solutions is beneficial to the development of metal oxide nanozymes.
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BIOCHEMICAL ENGINEERING JOURNAL
·
2022
·
IF 4.446
Shuping Zou,Zhentao Jiang,Heng Tang,Feng Cheng,Yaping Xue,Yuguo Zheng
The enzymatic asymmetric synthesis of L -phosphinothricin ( L -PPT) from 2-carboxyl-4-(hydroxymethylphosporyl) butyric acid (PPO) is a green and efficient method. In our previous works, we constructed a glutamate dehydrogenase (GluDH) and glucose dehydrogenase (GDH) co-expression strain, Escherichia coli BL21 (DE3)/pETDuet- gludh-gdh , which can asymmetrically reduce PPO to L -PPT. To improve the stability and recyclability of the biocatalyst , we developed a novel method for whole-cell immobilization with cross-linked cell aggregates (CLCAs) and employed immobilized cells in L -PPT production. Montmorillonite was used as a carrier, and dextran polyaldehyde (DPA) was developed as a new cross-linker for cell immobilization . The highest activity recovery (79.2%) was obtained under the following conditions: 20 g/L cell concentration, 0.9% montmorillonite concentration, 1.2% polyethyleneimine (PEI) concentration, and 1.2% DPA concentration. The half-lives of CLCAs were 169.10 h (35 °C), 17.39 h (45 °C), and 10.65 h (55 °C), which were 1.87-, 3.70-, and 10.78-fold than that of free cells, respectively. The CLCAs showed good reusability, retaining over 85% of their initial activities after 10 cycles of utilization. The total yield of L -PPT reached 667 mmol/g cells, and the enantiomeric excess value was more than 99%. The immobilized whole-cell in the form of CLCAs is a valuable biocatalyst for industrial applications.
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MICROCHIMICA ACTA
·
2024
·Vol. 191
·期 8
·1-10
·
IF 5.3
Wang Panxue,Liu Ying,Li Xiang,Li Cen,Li Guoliang
A ratiometric SERS aptasensor based on catalytic hairpin self-assembly (CHA) mediated cyclic signal amplification strategy was developed for the rapid and reliable determination of Escherichia coli O157:H7. The recognition probe was synthesized by modifying magnetic beads with blocked aptamers, and the SERS probe was constructed by functionalizing gold nanoparticles (Au NPs) with hairpin structured DNA and 4-mercaptobenzonitrile (4-MBN). The recognition probe captured E. coli O157:H7 specifically and released the blocker DNA, which activated the CHA reaction on the SERS probe and turned on the SERS signal of 6-carboxyl-x-rhodamine (ROX). Meanwhile, 4-MBN was used as an internal reference to calibrate the matrix interference. Thus, sensitive and reliable determination and quantification of E. coli O157:H7 was established using the ratio of the SERS signal intensities of ROX to 4-MBN. This aptasensor enabled detection of 2.44 × 10 2 CFU/mL of E. coli O157:H7 in approximately 3 h without pre-culture and DNA extraction. In addition, good reliability and excellent reproducibility were observed for the determination of E. coli O157:H7 in spiked water and milk samples. This study offered a new solution for the design of rapid, sensitive, and reliable SERS aptasensors. Graphical abstract
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BIOCHEMICAL ENGINEERING JOURNAL
·
2017
·
IF 2.892
Ya-Jun Wang,Xiao-Peng Chen,Wei Shen,Zhi-Qiang Liu,Yu-Guo Zheng
In our previous work, we constructed a carbonyl reductase (CR) and glucose dehydrogenase (GDH) co-expression strain E. coli BL21(DE3)/pCDFDuet- gdh - cr , and a biocatalytic process of chiral diol t -butyl 6-cyano-(3 R ,5 R )-dihydroxyhexanoate ((3 R ,5 R )- 2 ) was established by using its free cells. Herein, a (3 R ,5 R )- 2 process with celite-polyethyleneimine (PEI)-glutaraldehyde (GA) immobilized E. coli BL21(DE3)/pCDFDuet- gdh - cr whole cells was developed for the first time. It was demonstrated that immobilization via cross-linking was preferred, and the optimized immobilization conditions were as follows: 0.6% (w/v) celite, 4% (w/v) PEI and 1% (w/v) GA, pH7. The immobilizate can be used at pH 7.0, 30 °C for intermittent 7 batch, yielding a total of 17.5 g (3 R ,5 R )- 2 per gram of celite-PEI-GAimmobilizates in de p (diastereomeric excess) >99.5%. Compared with the free cells, there was a dramatic improvement in celite- PEI-GA immobilizate stability and recyclability. In this way, a promising platform technology based on a combination of cells immobilization and multiple enzymes co-expression is constructed, enabling efficiently converting inexpensive prochiral ketones to high-valued chiral alcohols.
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BIORESOURCE TECHNOLOGY
·
2014
·
IF 5.039
Yu-Cai He,Zhi-Cheng Tao,Xian Zhang,Zhen-Xing Yang,Jian-He Xu
An NADH-dependent reductase (CmCR) from Candida magnoliae was discovered by genome mining for carbonyl reductases. After CmCR was overexpressed in Escherichia coli BL21, a robust reductase-producing strain, recombinant E. coli CCZU-K14, was employed for the efficient synthesis of ethyl ( S )-4-chloro-3-hydroxybutanoate (( S )-CHBE) from the reduction of ethyl 4-chloro-3-oxobutanoate (COBE). After the optimization, the optimum reaction conditions were obtained. Notably, E. coli CCZU-K14 had broad substrate specificity in reducing both aliphatic and aromatic substrates, and excellent enantioselectivity of CCZU-K14 was observed for most of the tested substrates, resulting in chiral alcohols of over 99.9% ee . Moreover, COBE at a high concentration of (3000 mM) could be asymmetrically reduced to ( S )-CHBE in the high yield (>99.0%) and high enantiometric excess value (>99.9% ee ) after 14 h. Significantly, E. coli CCZU-K14 shows high potential in the industrial production of ( S )-CHBE and its derivatives (>99.9% ee ).
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CATALYSIS LETTERS
·
2021
·Vol. 151
·期 9
·2527-2536
·
IF 3.186
Du Hui-Jun,Luo Wei,Appiah Bright,Zou Zhi-Cheng,Yang Zhong-Hua,Zeng Rong,Luo Li
Abstract The intracellular NADPH insufficient supply is the main bottleneck to the synthesis of chiral alcohols by asymmetric reduction with whole-cell catalysis. Herein, we provide a novel strategy to strengthen intracellular NADPH supply through introducing an NADP + -dependent glyceraldehyde 3-phosphate dehydrogenase ( gap B from Bacillus subtilis 168) into the Embden-Meyerhof pathway and a NAD kinase ( yfj B from E. coli MG1655) to further enhance the NADP(H) pool. A recombinant E. coli ( E. coli BL21 (DE3)/pETDuet-1- gap B- yue D&pET28a- yfj B) was constructed to co-express gap B and yfj B with a carbonyl reductase gene yue D together. The result showed that the intracellular NADPH amount increased by 134.4% with the strategy. To the model reaction (asymmetric reduction of acetophenone to S -phenyl ethanol), the yield was 3.7-fold with this strategy compared to the control. This provides a technological route for strengthening the intracellular NADPH supply in E. coli for biocatalysis and biosynthesis. Graphic Abstract
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Nutrients
·
2024
·Vol. 16
·期 10
·1468
·
IF 4.8
Yan Zhang,Hong Huang,Chuanlin Luo,Xinfeng Zhang,Yanjing Chen,Fenfang Yue,Bingqing Xie,Tingtao Chen,Changwei Zou
Cadmium (Cd) is recognized as being linked to several liver diseases. Currently, due to the limited spectrum of drugs available for the treatment of Cd intoxication, developing and designing antidotes with superior detoxification capacity and revealing their underlying mechanisms remains a major challenge. Therefore, we developed the first next-generation probioticE. coli 1917-pSK18a-MT that delivers metallothionein (MT) to overcome Cd-induced liver injury in C57BL/6 mice by utilizing bacterial surface display technology. The results demonstrate thatE. coli 1917-pSK18a-MT could efficiently express MT without altering the growth and probiotic properties of the strain. Moreover, we found thatE. coli 1917-pSK18a-MT ameliorated Cd contamination-induced hepatic steatosis, inflammatory cell infiltration, and liver fibrosis by decreasing the expression of aminotransferases along with inflammatory factors. Activation of the Nrf2-Keap1 signaling pathway also further illustrated the hepatoprotective effects of the engineered bacteria. Finally, we showed thatE. coli 1917-pSK18a-MT improved the colonic barrier function impaired by Cd induction and ameliorated intestinal flora dysbiosis in Cd-poisoned mice by increasing the relative abundance of the Verrucomicrobiota. These data revealed that the combination ofE. coli 1917and MT both alleviated Cd-induced liver injury to a greater extent and restored the integrity of colonic epithelial tissues and bacterial dysbiosis.
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BIORESOURCE TECHNOLOGY
·
2024
·
IF 9.7
Yizhen Zhang,Yu-Cai He,Cuiluan Ma
Lignin is a plentiful and readily accessible renewable resource. Vanillylamine is a crucial raw material used to synthesize pharmaceuticals and high-value furan compounds that can be acquired by aminating lignin-derived vanillin (Van). However, effectually achieving the biocatalytic synthesis of vanillylamine has remained challenging. In this study, a dimethyl sulfoxide (DMSO)-H 2 O (1:9, vol/vol) bioreaction medium was constructed, and a recombinant E. coli ATA1012 carrying ω-transaminase from Caulobacter sp. D5 was used as the ω-transaminase biocatalyst to acquire the effectual biocatalytic synthesis of vanillylamine. Under optimized bioreaction conditions (37 ℃ and pH 7.5) by supplementary of isopropylamine (IPA) (Van/IPA = 1:5, mol/mol), 80–100 mM Van could be effectually converted by ATA1012 whole cells in DMSO-H 2 O (1:9, vol/vol) within 12 h, yielding 91.2 %–95.4 % vanillylamine, with >99 % selectivity. An efficient amination process was developed using ATA1012 with superior transaminase catalytic activity and substrate tolerance to effectively convert Van to vanillylamine in a DMSO-H 2 O medium.
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JOURNAL OF DAIRY SCIENCE
·
2025
·
IF 4.4
Bolong Fang,Yuzhi Li,Xiaole Zhao,Yan Liu,Lin Xu,Qiao Wang,Xin Liu,Zhiyong Gong,Weihua Lai
It is an urgent need of rapid and sensitive method for detection of Escherichia coli O157:H7 ( E. coli O157:H7), a class of hazardous foodborne pathogens in food safety. The traditional enzyme-linked immunosorbent assay (ELISA), a dominant rapid detection technic, takes disadvantages of low test sensitivity due to the insufficient enzyme loading capacity. In this study, we successfully synthesized the self-assembled Au/polydopamine (PDA)/HRP nanocomposites with the high enzyme loading on the outer surface and in the inner space. The high catalytic activity of Au/PDA/HRP was maintained by virtue of its hyperbranched flexible structure. For E. coli O157:H7 detection in milk samples, the proposed immunoassay achieved a visual cut-off value of 10 3 cfu mL −1 and a low limit of detection (LOD) of 2.8 × 10 2 cfu mL −1 , 33 and 46 times more sensitive than the traditional ELISA, respectively. The tremendous advantages of high sensitivity, excellent specificity and adequate recovery make it promising for sensitively monitoring various kinds of pathogenic bacteria in food safety.
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MICROCHIMICA ACTA
·
2017
·Vol. 185
·期 1
·1-9
·
IF 4.58
Zhu Tingfeng,Hu Yongjun,Yang Kang,Dong Ning,Yu Meng,Jiang Ningjing
The authors report on a surface-enhanced Raman scattering (SERS) nanoprobe for the specific detection of Escherichia coli O157:H7 ( E. coli O157:H7). Gold nanoparticles (AuNPs) were coated with a thick silica shell, and the Raman reporter (4,4′-dipyridyl) was embedded between gold nanoparticle and silica shell. This technique prevents any external effects on the AuNPs from the environment and avoids any interaction between the Raman reporter and possible impurities. Compared to the SERS nanoprobe of the conventional AuNP/AgNP type, the present nanoprobe can be applied in complex biochemical circumstances without aggregation because of its excellent stability. The SERS nanoprobeis stable for up to 50 h. The probe was applied to the SERS detection of E. coli O157:H7 by exploiting the Raman band peaking at 1612 cm −1 of 4,4′-dipyridyl (DP). The limit of detection is as low as 10 CFU·mL −1 . The technique was successfully employed to the detection of E. coli O157:H7 in real samples, achieving recoveries between 95.5 and 114.8%.
A novel surface-enhanced Raman scattering (SERS) nanoprobe based on the silica encapsulated gold nanoparticles (SEGNs) combining with the functionalized magnetic nanoparticles (MNPs), detecting E. coli O157:H7 with high sensitivity and specificity.
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