• Preventive Nutrition and Food Science
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• 제12권3호
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• pp.135-140
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• 2007

Antibacterial activities of the major phenolic components from Camellia sinensis L. were investigated against several pathogenic microorganisms including Gram-positive strains like Staphylococcus aureus ATCC 29213 and Streptococcus pyogens 308A; and Gram-negative strains like Escherichia coli ATCC 25922, Escherichia coli 078, Pseudomonas aeruginosa 9027, and Enterobacter cloacae 1321E. The MIC values demonstrate that both (-)-epicatechin and (-)-epigallocatechin were more considerably toxic against Staphylococcus aureus ATCC 29213 than the other two catechins like (-)-epicatechingallate and (-)-epigallocatechin-3-gallate. (-)-Epicatechingallate and (-)-epigallocatechin-3-gallate were most inhibitory against Escherichia coli ATCC 25922. As a result, (-)-epicatechin showed predominant antibacterial activities among tea varieties. The contents of major polyphenolic components such as four catechins, theaflavin, and quercetin were different according to fermentation processes. The total contents of four catechins were ranged from 13.81 to 1.33%, with (-)-epigallocatechin-3-gallate being dominant among tea varieties; theaflavin was found the characteristic pigment in fully-fermented black tea.

• 대한수의학회지
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• 제40권2호
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• pp.301-310
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• 2000

The antimicrobial susceptibility, genotypes of enterotoxins(LT, STa) and pili(K88, 987P), and plasmid profiles were investigated with 102 Escherichia coli isolated from piglets showing diarrhea in Korea. Almost of them were susceptible to ceftiofur(99%), cefquinone(97.1%). However they showed resistance to bacitracin(100%), streptomycin(98%), vancomycin(97%), trimethoprim/sulfamethoxazole(87.2%), tetracycline(84.3%) in antimicrobial susceptibility test. Moreover, all of the isolates demonstrated resistance to more than 2, and 78% of them were resistant to more than 8 of total 17 drugs. Multiplex PCRs for genotyping of enterotoxins(LT, STa) and pili(K88, 987P) were established with primers designed based on sequences from Genebank. Seventeen strains(16.6%) of the isolates had STa gene, 11 strains(10.8%) of them had both STa and LT genes, and 18 strains(17.8%) had K88 gene. But none of the isolates harbored a gene exclusively encoding LT. The gene encoding 987P pili was not found in all isolates. Fifty-four strains of 102 isolates(52.9%) had plasmid with various sizes ranging from 125kb to 1.1kb. Numbers of plasmid per isolates were also various, from 1 to 9. Distinctive relationship between plasmid profiles and genotypes of enterotoxins and pili in the isolates was not found. These results might provide the basic knowledge to establish strategies for the treatment and prevention of colibacillosis in piglets.

• Applied Microscopy
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• 제20권2호
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• pp.57-70
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• 1990

Characterization and electron microscopic visualization of the plasmid and the gene expression of Escherichia coli were carried out. Transcriptional units of active structural genes were observed after lysis of Escherichia coli cells. The ribosomes attached to the E. coli genome on mRNA molecule as polyribosomes. From this gradient of polyribosome length, we estimated location of mRNA synthesis initiation site. In this experiment, a granule is ofen present which may correspond to a RNA polymerase at the promoter site. pOX1, pOX7, pOX7A, $pOX7{\Delta}1$, pSTP36, pSTP21, pBR322, and pJH12 were visualized by way of electron microscope, and their estimated sizes were determined to be $5.70{\pm}0.08{\mu}m,\;2.15{\pm}0.10{\mu}m,\;2.14{\pm}0.12{\mu}m,\;7.39{\pm}0.08{\mu}m,\;4.03{\pm}0.04{\mu}m,\;1.50{\pm}0.03{\mu}m\;and\;1.25{\pm}0.09{\mu}m$ respectively. One micrometer of measured length corresponded to about 3.0 Kb. Mica-press adsorption method that allows selectivs visualization of the plasmid DNA released in situ from the bacterial cell is rapid and useful for visualization of plasmids. The released plasmid DNA was adsorbed preferently on mica in a divalent cation-free solution. Miller chromatin-spreading method was useful to observe the plasmid and transcripts. BAC method and cytochrome C monolayer were useful to observe the plasmid DNA. Our ability to visualize ultrastructural aspects of the expression of E. coli has given us a unique tool with which to study the regulation the level of an individual gene.

• Journal of Microbiology and Biotechnology
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• 제20권6호
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• pp.974-977
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• 2010

Cyclophilins contain the conserved activity of cis-trans peptidyl-prolyl isomerase, which is implicated in protein folding, and function as molecular chaperones. When the yeast cyclophilin A gene (cpr1) was subcloned into the prokaryotic expression vector pKM260, it was found that the expression of Cpr1 drastically increased the cell viability of E. coli BL21 when under abiotic stress conditions, as in the presence of cadmium, copper, hydrogen peroxide, heat, and SDS. Therefore, this study illustrates the importance of Cpr1 as a molecular chaperone that can improve the cellular stress responses when E. coli cells are exposed to adverse conditions, while also demonstrating its potential to increase the stability of E. coli strains utilized for the production of recombinant proteins.

• Clinical and Experimental Pediatrics
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• 제60권7호
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• pp.221-226
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• 2017

Purpose: Escherichia coli sequence type (ST) 131, a multidrug-resistant clone causing extraintestinal infections, has rapidly become prevalent worldwide. However, the epidemiological and clinical features of pediatric infections are poorly understood. We aimed to explore the characteristics of ST131 Escherichia coli isolated from Korean children with urinary tract infections. Methods: We examined 114 uropathogenic E. coli (UPEC) isolates from children hospitalized at Chung-Ang University Hospital between 2011 and 2014. Bacterial strains were classified into STs by partial sequencing of seven housekeeping genes (adk, fumC, gyrB, icd, mdh, purA, and recA). Clinical characteristics and antimicrobial susceptibility were compared between ST131 and non-ST131 UPEC isolates. Results: Sixteen UPEC isolates (14.0%) were extended-spectrum ${\beta}-lactamase$ (ESBL)-producers; 50.0% of ESBL-producers were ST131 isolates. Of all the isolates tested, 13.2% (15 of 114) were classified as ST131. There were no statistically significant associations between ST131 and age, sex, or clinical characteristics, including fever, white blood cell counts in urine and serum, C-reactive protein, radiologic abnormalities, and clinical outcome. However, ST131 isolates showed significantly lower rates of susceptibility to cefazolin (26.7%), cefotaxime (40.0%), cefepime (40.0%), and ciprofloxacin (53.3%) than non-ST131 isolates (65.7%, 91.9%, 92.9%, and 87.9%, respectively; P<0.001 for all). ESBL was more frequently produced in ST131 (53.3%) than in non-ST131 (8.1%) isolates (P<0.01). Conclusion: ST131 E. coli isolates were prevalent uropathogens in children at a single medical center in Korea between 2011 and 2014. Although ST131 isolates showed higher rates of antimicrobial resistance, clinical presentation and outcomes of patients were similar to those of patients infected with non-ST131 isolates.

• 대한수의학회지
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• 제57권1호
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• pp.9-15
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• 2017

To construct a novel vaccine candidate against bovine enterotoxigenic Escherichia coli (ETEC), FanC, the major subunit of K99 fimbriae adhesion, was inserted into secretion plasmid pYA3560 containing a ${\beta}-lactamase$ secretion system. This was then transformed into ${\Delta}asd$ ${\Delta}crp$ Salmonella (S.) Typhimurium and designated as JOL950. Secretion of recombinant fanC fimbrial antigens was confirmed by immunoblot analysis. Groups of mice were inoculated with single or double doses of JOL950. Another group was used as a negative control. Compared to control mice, all immunized mice had significantly higher levels (p < 0.05) of serum immunoglobulin (Ig)G, and secretory IgA against FanC. The IgG2a and IgG1 titer assays revealed that immunization highly induced IgG2a compared to that of IgG1, indicating that T helper-1- related cell-mediated immune responses may be elicited by JOL950. The results show that both systemic and mucosal immunities against selected fimbrial antigens of bovine ETEC expressed by a live attenuated S. Typhimurium strain are prominently produced in mice immunized with JOL950 via an oral route.

• Journal of Microbiology and Biotechnology
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• 제23권5호
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• pp.731-737
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• 2013

Seventy-four Shiga toxin-producing Escherichia coli (STEC) isolates belonging to the serotype O91:H21 were isolated from 1,643 asymptomatic human carriers in a STEC outbreak at Gwangju in Korea. Although the isolates did not cause any symptoms, all of them produced Shiga toxins 1 (Stx1) and 2 (Stx2). In order to determine why these strains cause no symptoms, we explored the differences in virulence potential between the asymptomatic STEC O91:H21 isolates and symptomatic STEC O91:H21 strains (ATCC 51435 and ATCC 51434). The asymptomatic STEC O91:H21 isolates showed strongly reduced cytopathic effects compared with the symptomatic strains when intact bacterial cells were used as an inoculant. Moreover, we found a reduced adherence phenotype when testing asymptomatic strains on HeLa cells. Real-time quantitative PCR results suggest that transcriptional repression of the genes encoding type-1 fimbriae occurs in the asymptomatic isolates but not in the symptomatic strains.

• BMB Reports
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• 제31권1호
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• pp.44-47
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• 1998

Asymmetry amongst nucleotide binding sites of Escherichia coli $F_1$-ATPase was examined using $^{19}F$ NMR signal from fluorinated analogs of adenine nucleotides bound to nucleotide binding sites. ADP-$CF_2-{PO_3}^{2-}$ showed no inhibitory effect to $F_1$-ATPase. But ADP-CHF-${PO_3}^{2-}$ (racemic mixture) showed competitive inhibition of $F_1$-ATPase with $K_i$ of $60\;{\mu}m$. ADP-CHF-${PO_3}^{2-}$ shows only negligible binding to $EF_1$ in the absence of $Mg^2+$. With the addition of $Mg^2+$ to the medium, the $^{19}F$ resonance of free ADP-CHF-${PO_3}^{2-}$ disappeared and the new broad resonances appeared. Appearance of more than two new asymmetric resonances following the binding of ADP-CHF-${PO_3}^{2-}$ to $EF_1$ may indicate that at least one of the isomers showed split resonances. This may suggest that the region between ${\alpha}$-and ${\beta}$-phosphate of ADP-CHF-${PO_3}^{2-}$ which is bound to catalytic sites is experiencing a different environment at different sites.

• 생명과학회지
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• 제23권5호
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• pp.703-709
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• 2013

본 연구에서는 ESBL을 생성하는 Escherichia coli의 Extended-spectrum ${\beta}$-lactamase (ESBL) 유전자와 퀴놀론 내성결정부위(qnr)의 유전자형과 항생제 내성 양상을 규명하고자 하였다. 임상검체에서 분리 된 E. coli 274개 균주를 대상으로 double-disk synergy test 검사를 실시하여 42개의 ESBL 생성 균주를 분리하였다. 검체별로는 소변에서 28균주가 분리되었으며, 객담에서 6균주, 농에서 3균주, 상처에서 2균주, 혈액에서 2균주 그리고 조직에서 1균주가 분리되었다. 이 균주들을 대상으로 ESBL 유전자와 퀴놀론 내성 유전자를 PCR을 이용하여 검색하였다. 35개의 균주가 1개 혹은 2개의 ESBL 유전자를 보유하고 있었다. ESBL 유전자의 분포는 CTX-M-1이 가장 많았으며, CTX-M-9과 TEM 유전자 순이었다. SHV, CTX-M-2와 CTX-M-8는 검출되지 않았다. qnr 유전자는 10개 균주에서 검출되었으며 유전형별로는 qnrB4, qnrB1, qnrS 1 순이었다. 2가지 이상의 ESBL 유전자를 동시에 보유한 균주와 ESBL과 qnr 유전자를 동시에 보유한 균주가 검출되었다. ESBL 유전자 보유균주는 cefotaxmie (80.0%), levofloxacin (82.9%)과 ampicillin (100%)에 고도내성을 보였다. qnr 유전자 보유 균주의 cefotaxmie, levofloxacin과 ampicillin에 대한 내성율은 각각 70%, 70%, 100%였다. ESBL 유전자들간의 그리고 qnr 유전자와의 동시 보유가 항생제 내성에 미치는 상승효과는 없었다. qnr 유전자 보유와 퀴놀론에 대한 내성 사이의 상관관계도 없었다.

• Korean Chemical Engineering Research
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• 제58권2호
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• pp.280-285
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• 2020

We have developed a constitutive display system of the Pseudomonas fluorescens SIK W1 TliA lipase on the cell surface of Escherichia coli using E. coli outer membrane protein C (OmpC) as an anchoring motif, which is an economical compared to induced system. For the constitutive expression of truncated OmpC-TliA fusion proteins, gntT104 promoter was employed. Cell growth was not affected by over expression of fusion protein during entire culture time, suggesting cell lysis was not a problem. The localization of truncated OmpC-TliA fusion protein on the cell surface was confirmed by immunofluorescence microscopy and measuring whole cell lipase activity. Constitutively displayed lipase was very stable, retaining activity enantioselectivity throughout the five repeated reactions. These results suggest that OmpC from E. coli be a useful anchoring motif for displaying enzymes on the cell surface without any inducers, and this stable surface display system can be employed for a broad range of biotechnological applications.