OBJECTIVE: To explore the genotyping characteristics of human fecal Escherichia coli( E. coli) and the relationships between antibiotic resistance genes (ARGs) and multidrug resistance (MDR) of E. coli in Miyun District, Beijing, an area with high incidence of infectious diarrheal cases but no related data. METHODS: Over a period of 3 years, 94 E. coli strains were isolated from fecal samples collected from Miyun District Hospital, a surveillance hospital of the National Pathogen Identification Network. The antibiotic susceptibility of the isolates was determined by the broth microdilution method. ARGs, multilocus sequence typing (MLST), and polymorphism trees were analyzed using whole-genome sequencing data (WGS). RESULTS: This study revealed that 68.09% of the isolates had MDR, prevalent and distributed in different clades, with a relatively high rate and low pathogenicity. There was no difference in MDR between the diarrheal (49/70) and healthy groups (15/24). CONCLUSION We developed a random forest (RF) prediction model of TEM.1 + baeR + mphA + mphB + QnrS1 + AAC.3-IId to identify MDR status, highlighting its potential for early resistance identification. The causes of MDR are likely mobile units transmitting the ARGs. In the future, we will continue to strengthen the monitoring of ARGs and MDR, and increase the number of strains to further verify the accuracy of the MDR markers.
Humans ; Escherichia coli/genetics* ; Escherichia coli Infections/epidemiology* ; Multilocus Sequence Typing ; Genotype ; Beijing ; Drug Resistance, Multiple, Bacterial/genetics* ; Anti-Bacterial Agents/pharmacology* ; Diarrhea ; Microbial Sensitivity Tests

Fusobacterium nucleatum is an opportunistic pathogenic bacterium that can be enriched in colorectal cancer tissues, affecting multiple stages of colorectal cancer development. The two-component system plays an important role in the regulation and expression of genes related to pathogenic resistance and pathogenicity. In this paper, we focused on the CarRS two-component system of F. nucleatum, and the histidine kinase protein CarS was recombinantly expressed and characterized. Several online software such as SMART, CCTOP and AlphaFold2 were used to predict the secondary and tertiary structure of the CarS protein. The results showed that CarS is a membrane protein with two transmembrane helices and contains 9 α-helices and 12 β-folds. CarS protein is composed of two domains, one is the N-terminal transmembrane domain (amino acids 1-170), the other is the C-terminal intracellular domain. The latter is composed of a signal receiving domain (histidine kinases, adenylyl cyclases, methyl-accepting proteins, prokaryotic signaling proteins, HAMP), a phosphate receptor domain (histidine kinase domain, HisKA), and a histidine kinase catalytic domain (histidine kinase-like ATPase catalytic domain, HATPase_c). Since the full-length CarS protein could not be expressed in host cells, a fusion expression vector pET-28a(+)-MBP-TEV-CarS_cyto was constructed based on the characteristics of secondary and tertiary structures, and overexpressed in Escherichia coli BL21-Codonplus(DE3)RIL. CarS_cyto-MBP protein was purified by affinity chromatography, ion-exchange chromatography, and gel filtration chromatography with a final concentration of 20 mg/ml. CarS_cyto-MBP protein showed both protein kinase and phosphotransferase activities, and the MBP tag had no effect on the function of CarS_cyto protein. The above results provide a basis for in-depth analysis of the biological function of the CarRS two-component system in F. nucleatum.
Humans ; Histidine Kinase/metabolism* ; Fusobacterium nucleatum/metabolism* ; Automobiles ; Protein Kinases/genetics* ; Escherichia coli/metabolism* ; Colorectal Neoplasms

The widespread of tigecycline resistance gene tet(X4) has a serious impact on the clinical efficacy of tigecycline. The development of effective antibiotic adjuvants to combat the looming tigecycline resistance is needed. The synergistic activity between the natural compound β-thujaplicin and tigecycline in vitro was determined by the checkerboard broth microdilution assay and time-dependent killing curve. The mechanism underlining the synergistic effect between β-thujaplicin and tigecycline against tet(X4)-positive Escherichia coli was investigated by determining cell membrane permeability, bacterial intracellular reactive oxygen species (ROS) content, iron content, and tigecycline content. β-thujaplicin exhibited potentiation effect on tigecycline against tet(X4)-positive E. coli in vitro, and presented no significant hemolysis and cytotoxicity within the range of antibacterial concentrations. Mechanistic studies demonstrated that β-thujaplicin significantly increased the permeability of bacterial cell membranes, chelated bacterial intracellular iron, disrupted the iron homeostasis and significantly increased intracellular ROS level. The synergistic effect of β-thujaplicin and tigecycline was identified to be related to interfere with bacterial iron metabolism and facilitate bacterial cell membrane permeability. Our studies provided theoretical and practical data for the application of combined β-thujaplicin with tigecycline in the treatment of tet(X4)-positive E. coli infection.
Humans ; Tigecycline/pharmacology* ; Escherichia coli/metabolism* ; Reactive Oxygen Species/therapeutic use* ; Plasmids ; Anti-Bacterial Agents/metabolism* ; Escherichia coli Infections/microbiology* ; Bacteria/genetics* ; Microbial Sensitivity Tests

The evaluation of the bioavailability of pollutants in soil is crucial to accurately assess the pollution risk, and whole-cell biosensor is one of the important tools for such evaluation. This study aimed to develop a novel whole-cell biosensor for the detection of methyl parathion in soil using. First, a whole-cell biosensor was constructed by the screened methyl parathion hydrolase mpd gene, the existing specific induction element pobR, and the pUC19 plasmid skeleton. Then, the detection method of methyl parathion in soil extracts was established using 96-well microtiter plate as carrier and five whole-cell biosensors as indicator. The method was applied in the detection of methyl parathion in tested and field soil extracts. Taking E. coli DH5α/pMP-AmilCP with the best detection performance as an example, this biosensor had a detection limit of 6.21-6.66 µg/L and a linear range of 10-10 000 µg/L for methyl parathion in four soil extracts. E. coli DH5α/pMP-RFP and E. coli DH5α/pMP-AmilCP methods have good detection performance for the analysis of methyl parathion in soil extract samples. This biosensor method can help to quickly assess the bioavailability of methyl parathion in soil, and thus help to understand the risk of soil pollution caused by organophosphorus pesticide methyl parathion.
Methyl Parathion/analysis* ; Pesticides/analysis* ; Organophosphorus Compounds ; Escherichia coli/genetics* ; Soil ; Farms ; Biosensing Techniques

c-Myc protein encoded by c-Myc (cellular-myelocytomatosis viral oncogene) gene regulates the related gene expression through the Wnt/β-catenin signaling pathway, and has received extensive attention in recent years. The purpose of this study was to express Helicoverpa armigera c-Myc gene (Ha-c-Myc) by using prokaryotic expression system, prepare the polyclonal antibody, examine the spatio-temporal expression profile of Ha-c-Myc, and investigate the possible function of Ha-c-Myc in regulating H. armigera sterol carrier protein-2 (SCP-2) gene expression. The Ha-c-Myc gene was amplified by PCR and cloned into a prokaryotic expression plasmid pET-32a(+). The recombinant plasmid pET-32a-Ha-c-Myc was transformed into Escherichia coli BL21. IPTG was used to induce the expression of the recombinant protein. Protein was purified by Ni²⁺-NTA column and used to immunize New Zealand rabbits for preparing the polyclonal antibody. The Ha-c-Myc expression levels in different developmental stages (egg, larva, prepupa, pupa, and adult) of H. armigera and different tissues (midgut, fat body, head, and epidermis) of the prepupa were determined by real-time quantitative reverse transcription PCR (qRT-PCR). Ha-c-Myc siRNA was synthesized and transfected into H. armigera Ha cells. The relative mRNA levels of Ha-c-Myc and HaSCP-2 in Ha cells were detected by qRT-PCR. Results showed that the pET-32a-Ha-c-Myc recombinant plasmid was constructed. The soluble Ha-c-Myc protein of about 65 kDa was expressed in E. coli. The polyclonal antibody was prepared. Western blotting analysis suggested that the antibody had high specificity. Enzyme linked immunosorbent assay (ELISA) showed that the titer of the antibody was high. Ha-c-Myc gene expressed at all developmental stages, with high levels in the early and late instars of larva, and the prepupal stage. Tissue expression profiles revealed that Ha-c-Myc expressed in various tissues of prepupa, with high expression level in the midgut, but low levels in the epidermis and fat body. RNAi results showed that the knockdown of Ha-c-Myc expression significantly affected transcription of HaSCP-2, leading to a 50% reduction in HaSCP-2 mRNA expression level. In conclusion, the Ha-c-Myc was expressed through a prokaryotic expression system, and the polyclonal anti-Ha-c-Myc antibody was obtained. Ha-c-Myc may promote the expression of HaSCP-2 and play an important role in the lipid metabolism of H. armigera. These results may facilitate further study on the potential role and function mechanism of Ha-c-Myc in H. armigera and provide experimental data for exploring new targets of green pesticides.
Animals ; Rabbits ; Escherichia coli/metabolism* ; Enzyme-Linked Immunosorbent Assay ; Moths/genetics* ; Blotting, Western ; Larva/genetics* ; Isoantibodies/metabolism* ; Antibody Specificity

Objective To prepare a rabbit anti-mouse coiled-coil domain containing 189 (Ccdc189) polyclonal antibody. Methods The pET-28a-Ccdc189 prokaryotic expression plasmid was constructed and transformed into E.coli BL21. IPTG was used to induce the expression of Ccdc189 prokaryotic protein. Adult male New Zealand rabbits were immunized with purified recombinant protein to obtain rabbit anti-mouse Ccdc189 polyclonal antibody. The specificity of the polyclonal antibody was identified by Western blot analysis, indirect ELISA and immunofluorescence histochemical staining. Results The pET-28a-Ccdc189 recombinant plasmid was successfully constructed and the expression of the Ccdc189 recombinant protein was induced. ELISA revealed that the titer of the polyclonal antibody was 1:1 000 000. Western blot and immunofluorescence staining demonstrated that the Ccdc189 polyclonal antibody could specifically identify the Ccdc189 prokaryotic protein and the Ccdc189 protein in adult wild-type mouse testis. Conclusion A polyclonal antibody with high specificity against mouse Ccdc189 was successfully created.
Rabbits ; Male ; Animals ; Mice ; Antibody Specificity ; Antibodies ; Enzyme-Linked Immunosorbent Assay ; Blotting, Western ; Recombinant Proteins ; Escherichia coli/genetics*

Objective To prepare specific mouse monoclonal antibody (mAb) against human adenovirus type 55 Hexon protein (HAdV55 Hexon). Methods The Hexon genes of HAdV55, 3, 4, 7, 16 and 21 were chemically synthesized as templates for PCR amplification. The prokaryotic expression plasmids pET28a-HAdV55 Hexon and eukaryotic expression plasmids pCAGGS-HAdV3, 4, 7, 16, 21 and 55 Hexon were constructed respectively. The pET28a-HAdV55 Hexon plasmid was transformed into E. coli competent cell BL21 (DE3) and was induced by IPTG. After the purified inclusion body was denatured and renatured, Hexon55 protein was purified by tangential flow filtration system. pCAGGS-HAdV55 Hexon was used to immunize BALB/c mice by cupping, and HAdV55 Hexon protein was used to booster immunization. The anti-HAdV55 Hexon mAb was prepared by hybridoma technique and the titer and subclass were determined. The specificity of antibody was identified by Western blot using HEK293T cells transfected with pCAGGS-HAdV55 Hexon and by immunofluorescence assay (IFA) using BHK cells transfected with pCAGGS-HAdV55 Hexon. Both clones with high titer were selected, and the cross-reactivity of pCAGGS-HAdV3, 4, 7, 16, 21 and 55 Hexon transfected cells were analyzed by Western blot analysis and IFA. Results PET28a-HAdV55 Hexon and pCAGGS-HAdV55 Hexon, 3, 4, 7, 16 and 21 expression plasmids were successfully constructed. BL21 transformed with pET28a-HAdV55 Hexon was induced by IPTG. The HAdV55 Hexon protein was mainly expressed in the form of inclusion body. After denaturation and renaturation, the purified HAdV55 Hexon protein was obtained by ultrafiltration. Six hybridoma cell lines secreting HAdV55 Hexon mAb were obtained. The antibody subclass analysis showed that 2 strains were IgG2a subtypes and 4 strains were IgG2b. Two specific HAdV55 Hexon antibodies with high titer were obtained, and there was no cross-reactivity with HAdV3, 4, 7, 16, 21 Hexon. Conclusion The specific mice mAb against HAdV55 Hexon provides an experimental basis for establishing its antigen detection method.
Animals ; Mice ; Humans ; Adenoviruses, Human/genetics* ; Escherichia coli/genetics* ; HEK293 Cells ; Isopropyl Thiogalactoside ; Blotting, Western ; Immunoglobulin G ; Antibodies, Monoclonal ; Antibody Specificity ; Mice, Inbred BALB C

Objective To express the monkeypox virus (MPXV) A23R protein in Escherichia coli and purify by Ni-NTA affinity column, and to prepare mouse antiserum against MPXV A23R. Methods The recombinant plasmid pET-28a-MPXV-A23R was constructed and transformed into Escherichia coli BL21 to induce the expression of A23R protein. After optimizing the conditions of expression, A23R protein was highly expressed. Recombinant A23R protein was purified by Ni-NTA affinity column and identified by Western blot analysis. The purified protein was used to immunize mice for preparing the A23R polyclonal antibody, and the antibody titer was detected by ELISA. Results The expression of A23R recombinant protein reached the peak under the induced conditions of 0.6 mmol/L isopropyl-β-D-thiogalactoside (IPTG), 37 DegreesCelsius and 20 hours. The purity of the protein was about 96.07% and was identified by Western blot analysis. The mice were immunized with recombinant protein, and the titer of antibody reached 1:102 400 at the 6th week after immunization. Conclusion MPXV A23R is expressed highly and purified with a high purity and its antiserum from mouse is obtained with a high titre.
Animals ; Mice ; Monkeypox virus ; Antibodies ; Enzyme-Linked Immunosorbent Assay ; Blotting, Western ; Recombinant Proteins ; Escherichia coli/genetics*

Objective: To investigate the antimicrobial resistance of food-borne diarrheagenic Escherichia coli (DEC) and the prevalence of mcr genes that mediates mobile colistin resistance in parts of China, 2020. Methods: For 91 DEC isolates recovered from food sources collected from Fujian province, Hebei province, Inner Mongolia Autonomous Region and Shanghai city in 2020, Vitek2 Compact biochemical identification and antimicrobial susceptibility testing platform was used for the detection of antimicrobial susceptibility testing (AST) against to 18 kinds of antimicrobial compounds belonging to 9 categories, and multi-polymerase chain reaction (mPCR) was used to detect the mcr-1-mcr-9 genes, then a further AST, whole genome sequencing (WGS) and bioinformatics analysis were platformed for these DEC isolates which were PCR positive for mcr genes. Results: Seventy in 91 isolates showed different antimicrobial resistance levels to the drugs tested with a resistance rate of 76.92%. The isolates showed the highest antimicrobial resistance rates to ampicillin (69.23%, 63/91) and trimethoprim-sulfamethoxazole (59.34%, 54/91), respectively. The multiple drug-resistant rate was 47.25% (43/91). Two mcr-1 gene and ESBL (extended-spectrum beta-lactamase) positive EAEC (enteroaggregative Escherichia coli) strains were detected. One of them was identified as serotype of O11:H6, which showed a resistance profile to 25 tested drugs referring to 10 classes, and 38 drug resistance genes were predicted by genome analysis. The other one was O16:H48 serotype, which was resistant to 21 tested drugs belonging to 7 classes and carried a new variant of mcr-1 gene (mcr-1.35). Conclusion: An overall high-level antimicrobial resistance was found among foodborne DEC isolates recovered from parts of China in 2020, and so was the MDR (multi-drug resistance) condition. MDR strains carrying multiple resistance genes such as mcr-1 gene were detected, and a new variant of mcr-1 gene was also found. It is necessary to continue with a dynamic monitoring on DEC contamination and an ongoing research into antimicrobial resistance mechanisms.
Humans ; Colistin/pharmacology* ; Anti-Bacterial Agents/pharmacology* ; Escherichia coli Infections/epidemiology* ; Escherichia coli Proteins/genetics* ; Drug Resistance, Bacterial/genetics* ; China/epidemiology* ; Escherichia coli ; Plasmids/genetics* ; Microbial Sensitivity Tests

The α-amino acid ester acyltransferase (SAET) from Sphingobacterium siyangensis is one of the enzymes with the highest catalytic ability for the biosynthesis of l-alanyl-l-glutamine (Ala-Gln) with unprotected l-alanine methylester and l-glutamine. To improve the catalytic performance of SAET, a one-step method was used to rapidly prepare the immobilized cells (SAET@ZIF-8) in the aqueous system. The engineered Escherichia coli (E. coli) expressing SAET was encapsulated into the imidazole framework structure of metal organic zeolite (ZIF-8). Subsequently, the obtained SAET@ZIF-8 was characterized, and the catalytic activity, reusability and storage stability were also investigated. Results showed that the morphology of the prepared SAET@ZIF-8 nanoparticles was basically the same as that of the standard ZIF-8 materials reported in literature, and the introduction of cells did not significantly change the morphology of ZIF-8. After repeated use for 7 times, SAET@ZIF-8 could still retain 67% of the initial catalytic activity. Maintained at room temperature for 4 days, 50% of the original catalytic activity of SAET@ZIF-8 could be retained, indicating that SAET@ZIF-8 has good stability for reuse and storage. When used in the biosynthesis of Ala-Gln, the final concentration of Ala-Gln reached 62.83 mmol/L (13.65 g/L) after 30 min, the yield reached 0.455 g/(L·min), and the conversion rate relative to glutamine was 62.83%. All these results suggested that the preparation of SAET@ZIF-8 is an efficient strategy for the biosynthesis of Ala-Gln.
Escherichia coli/genetics* ; Glutamine ; Zeolites/chemistry* ; Amino Acids