FOOD CONTROL
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2019
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IF 4.248
Yulin Zhu,Changzhu Li,Haiying Cui,Lin Lin
As a non-thermal sterilization method, pulsed light (PL) has been widely applied in food industries to control the microbial contamination, however little is known about the antimicrobial mechanism of PL. This study deeply investigated the antimicrobial mechanism of PL against Escherichia coli O157:H7 ( E. coli O157:H7). The changes of morphology, endoenzyme, entocyte, respiratory metabolism and DNA of E. coli O157:H7 after PL treatment were emphatically studied. TEM and SEM results exhibited that cell integrity was destroyed heavily after PL treatment. Entocyte including proteins, ATP and DNA were reduced remarkably for PL-treated samples. In addition, the activity of ATPase, β-galactosidase, alkaline phosphatase, topoisomerase, as well as the metabolism were inhibited for E. coli O157:H7 with PL treatment. The electron spin resonance spectrum validated the production of hydroxyl radical by PL, thus resulting in the elevation of intracellular reactive oxygen and the acceleration of cell death. Finally, PL displayed better antibacterial activity in carrot juice without adverse effect on its quality.
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MICROCHIMICA ACTA
·
2024
·Vol. 191
·期 8
·1-11
·
IF 5.3
Wang Chunxin,Deng Rong,Li Haiqin,Liu Zhigang,Niu Xiaofeng,Li Xiaochun
An intelligent colorimetric sensing platform integrated with in situ immunomagnetic separation function was developed for ultrasensitive detection of Escherichia coli O157: H7 ( E. coli O157: H7) in food. Captured antibody modified magnetic nanoparticles (cMNPs) and detection antibody/horseradish peroxidase (HRP) co-functionalized AuNPs (dHAuNPs) were firstly synthesized for targeted enrichment and colorimetric assay of E. coli O157: H7, in which remarkable signal amplification was realized by loading large amounts of HRP on the surface of AuNPs. Coupling with the optical collimation attachments and embedded magnetic separation module, a highly integrated optical device was constructed, by which in situ magnetic separation and high-quality imaging of 96-well microplates containing E. coli O157: H7 was achieved with a smartphone. The concentration of E. coli O157: H7 could be achieved in one-step by performing digital image colorimetric analysis of the obtained image with a custom-designed app. This biosensor possesses high sensitivity (1.63 CFU/mL), short detecting time (3 h), and good anti-interference performance even in real-sample testing. Overall, the developed method is expected to be a novel field detection platform for foodborne pathogens in water and food as well as for the diagnosis of infections due to its portability, ease of operation, and high feasibility. Graphical Abstract
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Biomolecules
·
2024
·Vol. 14
·期 4
·452
·
IF 4.8
Bingbing Zong,Yong Xiao,Peiyi Wang,Wei Liu,Mingxing Ren,Changyan Li,Shulin Fu,Yanyan Zhang,Yinsheng Qiu
Porcine extraintestinal pathogenicEscherichia coli(ExPEC) is a pathogenic bacterium that causes huge economic losses to the pig farming industry and considerably threatens human health. The quorum sensing (QS) system plays a crucial role in the survival and pathogenesis of pathogenic bacteria. Hence, it is a viable approach to prevent ExPEC infection by compromising the QS system, particularly the LuxS/AI-2 system. In this study, we investigated the effects of baicalin on the LuxS/AI-2 system of ExPEC. Baicalin at concentrations of 25, 50, and 100 μg/mL significantly diminished the survival ability of ExPEC in hostile environments and could inhibit the biofilm formation and autoagglutination ability in ExPEC. Moreover, baicalin dose-dependently decreased the production of AI-2 and down-regulated the expression level ofluxSin PCN033. These results suggest that baicalin can weaken the virulence of PCN033 by inhibiting the LuxS/AI-2 system. After the geneluxSwas deleted, AI-2 production in PCN033 was almost completely eliminated, similar to the effect of baicalin on the production of AI-2 in PCN033. This indicates that baicalin reduced the production of AI-2 by inhibiting the expression level ofluxSin ExPEC. In addition, the animal experiment further showed the potential of baicalin as a LuxS/AI-2 system inhibitor to prevent ExPEC infection. This study highlights the potential of baicalin as a natural quorum-sensing inhibitor for therapeutic applications in preventing ExPEC infection by targeting the LuxS/AI-2 system.
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ENVIRONMENTAL SCIENCE & TECHNOLOGY
·
2025
·
IF 11.3
Qi Yang,Han Yeong Kaw,Jing Yu,Xuejing Ma,Kun Yang,Lizhong Zhu,Wei Wang
The extensive prescription of fluoroquinolone antibiotics has resulted in their ubiquitous presence in the environment, fueling the ongoing development of antibiotic resistance. Besides antibiotics, fluoroquinolone production intermediates, an overlooked category of pollutants that oftentimes possess the intact fluoroquinolone core structure, may also contribute to this public health crisis. To assess their relative potency and collectively examine the structural effects of fluoroquinolones on resistance development, wild-type Escherichia coli K12 was exposed to ten fluoroquinolone antibiotics and five intermediates at their environmentally relevant concentrations for 30 days. Phenotypic resistance alterations revealed that the absence of the C7 ring system in fluoroquinolones significantly impaired their capacity to induce resistance in E. coli, potentially due to diminished oxidative DNA damage and gyrase-mediated dsDNA breaks. Genetic and transcriptional analyses indicated that a uniform resistance mechanism emerged under both antibiotic and intermediate stress. Quantitative structure–activity relationship (QSAR) analysis further emphasized the positive impact of both basic nitrogenous heterocyclic rings at C7 (particularly the hydrogen-bond-donor pharmacophores) and aromatic rings at N1 in promoting resistance development, while highlighting the adverse effects of hydrophobic and hydrogen-bond-donor groups at N1. A robust QSAR model was developed and applied to assess the relative risks of other 105 fluoroquinolones. This study underscored the direct role of fluoroquinolone production intermediates in promoting environmental antibiotic resistance and illustrated how different structural features of fluoroquinolone pollutants will influence this process, offering theoretical insights for future antibiotic design and environmental regulation efforts.
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APPLIED MICROBIOLOGY AND BIOTECHNOLOGY
·
2016
·Vol. 100
·期 11
·5079-5088
·
IF 3.376
Liu Di,Guo Hua,Zheng Wenyun,Zhang Na,Wang Tianwen,Wang Ping,Ma Xingyuan
Heat-labile enterotoxin (LT) is a protein toxin produced by enterotoxigenic Escherichia coli (ETEC). As a bacterial toxin, LT holotoxin can enter intestinal epithelial cells and cause diarrhea. In addition, LT is also a powerful mucosal adjuvant capable of enhancing the strong immune responses to co-administered antigens. However, the LT immunological mechanism is still not clear in some aspects, especially with the respect to how the LTA subunit functions alone. Here, we discovered that the A 2 domain of LTA could carry a fluorescent protein into cells, whose function is similar to a cell-penetrating peptide. The transmembrane-transporting ability of the A 2 domain is non-specific in its cell-penetrating function, which was shown through testing with different cell types. Moreover, the LTA 2 fusion protein penetrated a fluorescently labeled cell membrane that identified LTA 2 internalization through membrane transport pathways, and showed it finally localized in the endoplasmic reticulum. Furthermore, low-temperature stress and pharmacological agent treatments showed that the LTA 2 internalization route is a temperature-dependent process involving the clathrin-mediated endocytosis and the macropinocytosis pathways. These results could explain the internalization of the LTA subunit alone without the LTB pentamer, contributing to a better understanding of LTA working as a mucosal adjuvant; they also suggest that the A 2 domain could be used as a novel transport vehicle for research and treatment of disease.
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PROCESS BIOCHEMISTRY
·
2017
·
IF 2.497
Hui Zhang,Mengya Li,Jie Li,Guangli Wang,Feng Li,Minghua Xiong
Nitrile hydratase (NHase) has attracted substantial attention for industrial applications to produce large-scale amides. Several NHases have been investigated for functional expression in Escherichia coli ( E. coli ). A Fe-type NHase was obtained from an acetamiprid-degrading bacterium, Pseudoxanthomonas sp. AAP-7 and functionally expressed in E. coli BL21 (DE3). No significant NHase activity was detected from the E. coli expressing either the NHase gene alone or NHase and P46K genes transcribed as one unit. Purified recombinant NHase, co-expressed with P46K on two separate plasmids, exhibited the maximal enzyme activity. Furthermore, a GST tag attached to the N-terminus of α subunit resulted in a slight increase in the solubility and stability of NHase compared with a His tag at the C-terminus of β subunit. When co-expressed with the chaperones GroEL-GroES, the yield of the soluble recombinant NHase was improved substantially, while a small decrease in NHase activity was observed. The putative activator P46K was strictly required for production of the recombinant NHase for full enzyme activity, although the chaperones GroEL-GroES appeared to assist NHase to fold properly. This study of the expression of a fully active Fe-type NHase would provide another example to enhance our understanding of NHase biosynthesis.
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WATER RESEARCH
·
2024
·
IF 11.4
Xiaofeng Han,Long Fu,Jing Yu,Kunting Li,Ziqing Deng,Ruihao Shu,Dali Wang,Jing You,Eddy Y. Zeng
Microplastics (MPs) and antibiotics co-occur widely in the environment and pose combined risk to microbial communities. The present study investigated the effects of erythromycin on biofilm formation and resistance mutation of a model bacterium, E. coli , on the surface of pristine and UV-aged polystyrene (PS) MPs sized 1–2 mm. The properties of UV-aged PS were significantly altered compared to pristine PS, with notable increases in specific surface area, carbonyl index, hydrophilicity, and hydroxyl radical content. Importantly, the adsorption capacity of UV-aged PS towards erythromycin was approximately 8-fold higher than that of pristine PS. Biofilms colonizing on UV-aged PS had a greater cell count (5.6 × 10 8 CFU mg −1 ) and a higher frequency of resistance mutation (1.0 × 10 −7 ) than those on pristine PS (1.4 × 10 8 CFU mg −1 and 1.4 × 10 −8 , respectively). Moreover, erythromycin at 0.1 and 1.0 mg L − 1 significantly ( p < 0.05) promoted the formation and resistance mutation of biofilm on both pristine and UV-aged PS. DNA sequencing results confirmed that the biofilm resistance was attributed to point mutations in rpoB segment of the bacterial genome. qPCR results demonstrated that both UV aging and erythromycin repressed the expression levels of a global regulator rpoS in biofilm bacteria, as well as two DNA mismatch repair genes mutS and uvrD , which was likely to contribute to increased resistance mutation frequency.
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ELECTROANALYSIS
·
2024
·
IF 2.7
Jiaqi Fu,Jincheng Du,Ting Hou,Zhong Wang,Liyuan Sui,Jinlian Li,Yanli Zhao,Ximing Cui,Dongmei Wu
Electrochemistry with purines as indicators may be a promising new method for antibiotic activity testing. However, the traditional electrochemical detection method (S-LSV) requires a long accumulation time for purines and has low signal intensity. High-temperature treatment of bacterial samples may significantly enhance the signal intensity and speed of detection. However, this process may also impact the structure and metabolism of bacteria. Further research is necessary to determine how electrochemical signals respond to antibiotic antibacterial activity. In this paper, the electrochemical detection method based on heat-treated Escherichia coli ( E. coli , H-LSV) was used to investigate the effects of 11 antibiotics with four different antibacterial mechanisms on the electrochemical behavior of E. coli . The results showed that compared to the S-LSV, the electrochemical signal of E. coli detected by the H-LSV increased by 362%, and showed a strong linear relationship with bacterial counts up to 1.88×10 8 CFU/mL, with a detection limit of 1.15×10 6 CFU/mL. The electrochemical signal consistently correlated with changes in viable E. coli counts following treatment with the four different antibacterial mechanisms. HPLC analysis further confirmed that the changes in purine contents in bacteria after antibiotic treatment were consistent with the trends in electrochemical signals. The evaluation of antibiotic antibacterial ability by H-LSV showed good consistency with results from plate counting and turbidity methods, but was closer to the results of plate counting. The inhibition rates of antibiotics on E. coli detected by H-LSV and S-LSV also showed high consistency, indicating that short-term high-temperature treatment of E. coli did not affect the response of the bacterium to the inhibitory activity of antibiotics.
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BIORESOURCE TECHNOLOGY
·
2024
·
IF 9.7
Jing Wang,Min Du,Xin Wang,Junchen He,Alei Zhang,Kequan Chen
To achieve industrial-scale putrescine production, a high efficient bio-synthesis of putrescine involving arginase (ARG, EC 3.5.3.1) and L-ornithine decarboxylase was evaluated here. Among the four arginases tested, ARG BT from Bos Taurus showed the highest activity (1966 U/mg). Compared to the L-arginine decarboxylase (ADC) pathway, the strain expressing ARG BT and L-ornithine decarboxylase (SpeC) produced 28.7 g/L putrescine, a 38.6 % increase. Two pyridoxal phosphate (PLP) salvage pathways were evaluated, and the strain BL-P Tac -PdxK co-expressed pyridoxal kinase (PdxK) performed better. D-Glucose was used as the co-substrate to improve the putrescine titer further. Under optimal conditions, 43.6 g/L putrescine was produced from 87.1 g/L L-arginine, and 76 g/L putrescine was synthesized on a 0.5 L scale. Using L-arginine fermentation broth (60 g/L) as the substrate, a titer of 30 g/L putrescine was achieved. This efficient biotransformation process presented here enables feasible industrial-scale putrescine production.
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Nature Communications
·
2025
·Vol. 16
·期 1
·1-16
·
IF 15.7
Fang Lixia,Hao Xueyan,Fan Jie,Liu Xiaolei,Chen Yaru,Wang Lian,Huang Xiaoying,Song Hao,Cao Yingxiu
Microbial physiology plays a pivotal role in construction of superior microbial cell factories for efficient biosynthesis of desired products. Here we identify that pcnB repression confers improved physiology for overproduction of free fatty acids (FFAs) in Escherichia coli through genome-scale CRISPRi modulation combining fluorescence-activated cell sorting (FACS) and next-generation sequencing (NGS). The repression of pcnB can enhance the stability and abundance of the transcripts of genes involved in the proton-consuming system, thereby supporting global improvements in membrane properties, redox state, and energy level. Based on pcnB repression, further repression of acrD increases FFAs biosynthesis by enhancing FFAs efflux. The engineered strain pcnB i - acrD i - fadR + achieves 35.1 g L −1 FFAs production in fed-batch fermentation, which is the maximum titer reported to date in E. coli . This study highlights the significance of uncovering hidden genetic determinants that confer improved microbial physiology for enhancing the biosynthesis of desired products.
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INTERNATIONAL JOURNAL OF ANTIMICROBIAL AGENTS
·
2024
·
IF 4.9
Haifeng Liu,Ying Zhang,Zeyong Zhong,Yanchun Gong,Pingting Yu,Yuhan Yang,Yichi Zhang,Tieli Zhou,Lijiang Chen
Colistin (COL) was once considered to be the last line of defence against multidrug-resistant bacteria belonging to the family Enterobacteriaceae . Due to the misuse of COL, COL-resistant (COL-R) Enterobacteriaceae have emerged. To address this clinical issue and combat COL resistance, novel approaches are urgently needed. In this study, the in vitro and in vivo antimicrobial and antibiofilm effects of the immunomodulator AS101 were investigated in combination with COL against COL-R Escherichia coli ( E. coli ) and Klebsiella pneumoniae ( K. pneumoniae ). Checkerboard assay, time-kill assay, and scanning electron microscopy confirmed the in vitro antimicrobial phenotype, whereas, crystal violet staining and multidimensional confocal laser scanning microscopy with live/dead staining confirmed the antibiofilm capability of the combination therapy. Moreover, the Galleria mellonella infection model and the mouse infection model indicated the high in vivo efficacy of the combination therapy. Additionally, cytotoxicity experiments performed using human kidney-derived HK-2 cells and hemolysis assays performed using human erythrocytes collectively demonstrated safety at effective combination concentrations. Furthermore, quantification of the expression of inflammatory cytokines via ELISA confirmed the anti-inflammatory advantage of combination therapy. At the mechanistic level, changes in outer and inner membrane permeability and accumulation of ROS levels, which might be potential mechanisms for synergistic antimicrobial effects. In conclusion, this study found that AS101 can restore COL susceptibility in clinical COL-R E. coli and K. pneumoniae and also has synergistic antibiofilm and anti-inflammatory capabilities. This study provided a novel strategy to combat clinical infections caused by COL-R E. coli and K. pneumoniae .
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Food Analytical Methods
·
2025
·
IF 3
Qi Yan,Wang Fengyang,Jiang Yanjun,Ji Lei,Xiong Xiaohui,Liu Yuanjian
Escherichia coli O157:H7 ( E. coli O157:H7) is a foodborne pathogen with high pathogenicity and lethality, capable of producing substantial amounts of Vero toxin (VT), posing a significant threat to human health. Consequently, a platform based on the bipolar electrode-electrochemiluminescence (BPE-ECL) and loop-mediated isothermal amplification (LAMP) was constructed for the detection of E. coli O157:H7. Firstly, LAMP technology is utilized to efficiently obtain the amplified product (double-stranded DNA, dsDNA) of E. coli O157:H7. On the one hand, SYBR Green was added to the amplified product to detect E. coli O157:H7 by colorimetric determination. The concentration of 10 CFU mL −1 E. coli O157:H7 can only obtain qualitative analysis, to determine the presence of the target bacteria. On the other hand, methylene blue (MB) molecules were embedded in the dsDNA through electrostatic interactions. Then, by dropwise adding the mixture onto the cathode of the BPE, the ECL signal of Ru(bpy) 3 2+ onto the anode was generated. Specifically, the BPE-ECL sensor displayed superior sensitivity for E. coli O157:H7 with a detection limit of 10 CFU mL −1 and a wide linear concentration range of 10 1 –10 6 CFU mL −1 . In summary, this sensor can effectively enhance the sensitivity and reliability of detection when compared to traditional colorimetric methods, and achieve qualitative and quantitative detection of E. coli O157:H7 by measuring the anode ECL signal of Ru(bpy) 3 2+ .
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