• Archives of Pharmacal Research
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• 제19권5호
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• pp.353-358
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• 1996

E. coli 11 and E. coli 101, clinical isolates of Escherichia coli were resistant to various quinolones, especially MICs to norfloxacin of both strains were higher than 100 mg/ml. In the presence of carbonyl cyanide m-chlorophenylhydrazone, a proton gradient uncoupler, norfloxacin uptake in both strains was increased, suggesting that an efflux system play an important role in the norfloxacin resistance. Outer membrane proteins of the susceptible and resistant strains which could affect the route of norfloxacin entry into cells were different. When quinolone resistance determining region(QRDR) of gyrA was amplified using PCR and cut with Hinf I, QRDR in the susceptible strain yielded two fragments while QRDRs in E. coli 11 and E. coli 101 yielded only one uncut fragment. When DNA sequence of QRDR was analyzed, there were two mutations as Ser-83 and Asp-87 in both resistant strains. these residues were changed to Leu-83 and Asn-87, respectively. These results showed that the norfloxacin resistance of E. coli 11 and E. coli 101 was resulted from multiple changes-an altered DNA gyrase A subunit, a change in route of drug entry, and reduction in quinolone concentration inside cells due to an efflux system.

• 대한수의학회지
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• 제31권1호
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• pp.55-61
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• 1991

The correlation between in vitro Congo-red binding properties of E coli and in vivo invasiveness of the organisms in SPF chickens and mice was investigated. Congo-red positive E coli colonies were dark-red color with a typical colonial morphology of rough appearance when grown on Congo-red medium, while Congo-red negative colonies showed pale-pink color and smooth surfaced colonial morphology. Pathogenicity of 10 Congo-red positive E coli for mice was observed in 92.5% but that of 5 Congo-red negative E coli was 45%. Invasiveness of 10 Congo-red positive E coli for chickens was observed in 96% of the SPF chickens tested but that of 5 Congo-red negative E coli was 16% only. These results of pathogenicity studies with E coli isolates indicate a significant correlation between Congo-red binding ability and virulence in avian Escherichia coli.

• 한국미생물·생명공학회지
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• 제13권4호
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• pp.349-354
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• 1985

Plasmid pBR322와 runaway Plasmid pSY343을 vector로 사용하여 E. stearothermophilus IAM 11062내의 $\alpha$-amylase 유전자를 E. coli내에 클로닝 하였다. 이때 얻어진 $\alpha$-amylase유전자는 제한효소 Hind III의 말단을 갖고 있는 4.7kb의 크기였으며 E. coli내에서 이들 유전자는 비교적 안정적 있게 유지되고 발현되었다. 재조합 $\alpha$-amylase유전자가 클로닝된 E. coli는 B. stearothermophilus IAM 11062보다 3배의 $\alpha$-amylase를 더 많이 생성하였다. EDTA를 사용한 osmotic shock 방법에 의하여 E. coli내에서 생성된 $\alpha$-amylase는 그 효소 생성량의 75%정도가 periplasm에 존재함이 밝혀졌다. 재조합된 $\alpha$-amylase 유전자에 의해서 E. coli에서 생성된 $\alpha$-amylase는 최적 작용온도가 55$^{\circ}C$로서 이들의 열안정성과 분자량(61,000)도 B. stearothermophilus IAM 11062의 $\alpha$-amylase와 거의 동일하게 나타나 E. coli와 B. stearothermophilus IAM 11062에서 생성된 $\alpha$-amylase는 효소학적 성질이 같음을 보여주었다.

• 한국미생물·생명공학회지
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• 제29권3호
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• pp.169-175
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• 2001

E coli O157:H7은 식품과 물에 의해서 전염되는 식중독균으로서 이들의 생성하는 vero toxin 이 장관의 상피세포내로 침입되어 질병을 유발시키게 된다. 또한 E coli O157:H7 이 체내에 감염되기 위해서는 유산균과 마찬가지로 장상피세포에 정착하여야 한다. 따라서 본 연구에서는 비피더스균이 E. coli O157:H7의 생육 및 정착에 대해서 억제효과가 있는지를 파악하기 위해서 비피더스균과 E. coli O157:H7을 혼합 배양했을 때의 억제 효과 비피더스균의 Caco-2 세포 정착에 따른 억제 효과 등을 조사하였다. B infantis K9 균주와 E. coli O157:H7을 단독 또는 혼합배양하면서 배양시간에따른 pH 균수 암모니아 함량을 측정하였다. 그결과 배양시간이 결과되어 B infantis K9 균주에 의해서 산성물질이 생성되면서 E. coli O157:H7의 균수는 급격히 감소되는것으로 나타났다. 한편 암모니아 함량은 E. coli O157:H7 단독배양 시료에 비해서 혼합배양 시료에서 8시간 이후부터 감소되는 것으로 볼때 비피더스 균 E. coli O157:H7이 생성하는 암모니아를 이용하는것으로 확인되었다.B infantis K9 균주와 E. coli O.157:H7 P4 균주를 정착시기를 달리하여 Caco-2 세포에 혼합 정착시켰을 때 B. onfantis K9 균준느 정착시기에 상관없이 유사한 정착율을 나타냈다. 반면에 B infantis K9 균주가 2시간 전에 미리 정착되어 있을 때에는 E. coli O157: HP P4 균주의 정착율이 2.6%에서 1.86%로 감소되는 경향을 보였다. 결론적으로 비피더스균의 E coli O157:H7에 대한 생육 및 정착 억제를 검토한 결과 생육억제효과는 비피더스균에 의해서 생성된 산성물질 에 의해서 pH4.40 이하 일때 저해 효과를 보였으며 비피더스균과 E. coli O157:H7 이 정착 부위를 동일하게 이용하지만 비피더스균이 우선적으로 정착이 되었을 때 E. coli O157:H7의 정착율이 저하되는 결과를 나타냈다.

• KSBB Journal
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• 제19권4호
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• pp.331-334
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• 2004

재조합 E. coli를 이용한 MCL-PHA의 생산에서 fatty acid pathway로부터 PHA 생합성 전구체 물질들이 만들어진다는 사실과 함께 이에 관여하는 enzymes이 밝혀지고 있다. 본 논문에서는 protein homology search로부터 탐색된 paaG와 ydbU genes의 PHA 생합성에서의 역할을 확인하기 위하여 paaG와 ydbU gene이 각각 knock-out된 mutant E. coli strains 를 제작하였다. 제작된 mutant E. coli들은 모균주들보다 낮은 PHA 농도와 함량을 가졌으며, 이러한 결과들로부터 paaG와 ydbU는 fatty acid pathway에서 PHA synthesis의 전구체 물질들을 공급한다는 사실을 확인하였다. 또한, 새로운 FadB homologous enzyme YgfG를 탐색하였으며, ygfG gene이 overexpression된 균주와 ygfG mutant를 제작하여 PHA 합성을 실험한 결과 ygfG도 paaG와 ydbU와 유사한 역할을 한다는 사실을 밝혔다. 이러한 연구결과들은 E. coli에서의 MCL-PHA 단량체들의 합성 경로를 확인하여 효과적인 PHA 생산 균주를 제작할 수 있게 할 것이다.

• Clinical and Experimental Reproductive Medicine
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• 제49권1호
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• pp.33-39
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• 2022

Objective: Male genital tract infections have been associated with infertility, and Escherichia coli has drawn increasing attention as an important bacterium in this context. This investigation aimed to characterize and compare the distributions of O-antigen serogroups of E. coli in the semen samples of fertile and infertile men. Methods: In this case-control study, semen samples were collected from 618 fertile and 1,535 infertile men. The E. coli-positive samples were evaluated in terms of concentration, morphology, viability, and motility parameters according to the World Health Organization 2010 guidelines. Finally, different serogroups of E. coli were identified by multiplex polymerase chain reaction targeting the O-antigen variations of the bacterium. Results: The prevalence of E. coli among fertile men was significantly higher than among infertile men (p<0.001). The sperm morphology, viability, and motility in the E. coli-positive fertile group were significantly higher than in the E. coli-positive infertile group (p<0.001). E. coli O6 was the most prevalent serogroup found in both groups. However, there was no significant difference in the frequency of different serogroups of E. coil between the two groups (p=0.55). Conclusion: Despite the higher prevalence of E. coli among fertile men, E. coli had more detrimental effects on semen parameters in infertile men. There was no significant difference in E. coli serogroups between the fertile and infertile groups.

• 대한미생물학회지
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• 제12권1호
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• pp.1-10
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• 1977

40 strains of E. coli isolated from residents of a doctorless area in Korea in 1976 and 40 strains of E. coli isolated from patients of Seoul National University Hospital from 1975 to 1976 were examined for susceptibilities to 14 antimicrobial agents by the agar dilution method. The susceptibilities of the two groups to each antimicrobial agent were compared and correlations in the antimicrobial susceptibility of the 80 strains of E. coli among the 14 antimicrobial agents were also analyzed. The results were obtained as follow: 1. With Tetracycline, Oxytetracycline, Doxycycline and Ampicillin, the mean MIC's of E. coli isolated from patients of Seoul National University Hospital were 8.6 to 14 times higher than. those of E. coli isolated from residents of a doctorless area. 2. With Streptomycin, Minocycline and Carbenicillin, the mean MIC's o{ E. coli isolated from patients of Seoul National University Hospital were 4.1 to 5.6 times higher than those of E. coil isolated from residents of a doctorless area. 3. With Kanamycin, Penicillin and Cotrimoxazole, the mean MIC's of E. coli isolated from patients of Seoul National University Hospital were 2.6 to 3.7 times higher than those of E. coli isolated from residents of a doctorless area. 4. There were no significant differences in susceptibility to Erythromycin respectively between E. coli isolated from patients of Seoul National University coli isolated from residents of a doctorless area. 5. E. coli isolated from patients of Seoul National University Hospital were resistant to Erythromycin(100%), Streptomycin(75%), Tetracycline(72.5%), Oxytetracycline(72.5%), Doxycycline(72.5%), Minocycline(67.5%), Penicillin(82.5%), Ampicillin(60%) and Carbenicillin(65%) respectively and were sensitive to Gentamicin(97.5%), Cephalexin(92.5%) and Kanamycin(72.5%) respectively. 6. E. coli isolated from residents of a doctorless, area were resistant to Erythromycin(100%), Streptomycin(40%) and Penicillin(50%) respectively and were sensitive to Gentamicin(100%), Kanamycin(92.5%), Tetracycline(87.5%), Oxytetracycline(87.5%), Doxycycline(87.5%), Minocycline(87.5%), Ampicillin(95%), Carbenicillin(92.5%) and Cephalexin(97.5%) respectively. 7. There were high correlations among the suscebtibilities of the 80 strains of E. coli to Tetracycline analogues(Tetracycline, Oxytetracycline, Doxycycline and Minocycline) and among susceptibilities of the 80 strains of E. coli to Penicillin analogues(Penicillin, Ampicillin and Carbenicillin). 8. There were relatively high correlations between the susceptibilities of the 80 strains of E. coli to Penicillin analogues and those to Tetracycline analogues, between the susceptibilities to Penicillin analogues and those to Streptomycin and between the susceptibilities to Tetracycline analogues and those to Streptomycin.

• 미생물학회지
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• 제27권1호
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• pp.16-20
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• 1989

The effect of E. coli plasmid DNA sequences contained by chimeric vectors on plasmid replication was investigated. We constructed YRp7- or 2.$\mu$m circle-based plasmids containing E. coli plasmid DNA sequences and those not containing it. By examining their maintenance in yeast, we showed that plasmid without E. coli plasmid DNA sdquences was nore stable and presented higher copy number, and espressed higher level of hepatitis B viral surface antigen as a foreign gene. This result suggested that E. coli plasmid DNA sequences within chimeric plasmid somehow inhibited plasmid replication in yeast.

• 한국식품위생안전성학회지
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• 제31권6호
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• pp.393-398
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• 2016

본 연구에서는 선택배지와 건조필름을 이용하여 신선편이 엽채류 3종(양상추, 양배추, 어린잎채소)에서 병원성 E. coli를 분리하였고, 의심집락 동정을 위해 생화학적 분석법을 사용하여 동정한 후 결과를 비교 분석하였다. 양상추 20 g, 양배추 20 g, 어린잎채소 10 g에 병원성 E. coli 혼합 균액(Enterohemorrhagic E. coli NCCP11142, Enterotoxigenic E. coli NCCP14037, Enteropathogenic E. coli NCCP14038, Enteroaggregative E. coli NCCP14039, Enteropathogenic E. coli NCCP15661)을 최종농도가 1, 2, 3 log CFU/g이 되도록 접종하였고, BPW (80~90 ml)을 넣은 후 60초 동안 균질화하여 분석하였다. 연구결과, 모든 시료에서 건조필름 시험 양성, 양상추 시료 일부(최종농도 3 log CFU/g 접종시료)를 제외한 모든 시료에서 증균배양법을 이용한 정성시험결과가 음성으로 나타났다. 증균배양과 건조필름 시험을 통해 분리한 병원성 E. coli를 이용하여 생화학적 분석을 실시한 결과, 양상추에서 분리한 병원성 E. coli의 경우, API 20E 100% (44/44), Microgen GNA 100% (44/44), Food System 66.7% (10/15)의 동정률이 나타났다. 양배추의 경우, API 20E 64.7% (22/34), Microgen GNA 50% (16/32), Food System 60% (9/15), 어린잎채소의 경우, API 20E 65.1% (28/43), Microgen GNA 62.3% (27/43), Food System 53.3% (8/15)가 병원성 E. coli로 동정되었다. 본 연구의 결과는 신선편이 엽채류에 대한 병원성 E. coli 검출법 선택에 유용하게 이용될 것으로 판단된다.

• 한국식품영양과학회지
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• 제24권2호
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• pp.280-285
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• 1995

To develop natural food preservatives, antimicrobial effect of the ethanol extract of leaf mustard against E. coli and S. aureus were examined in terms of compositions and leakage of cellular materials in the microorganisms treated with the extract. No effect of the concentration of ethanol extract on the fatty acid composition of E. coli and S. aureus at logarithmic phase was showen, but the content of palmitic and palmitoleic acid of E. coli slightly increased and decreased, respectively, and the content of palmitic and margaric acid of S. aureus slightly increased, when compared to each control. Ethanol extract did not affect most of the amino acids E. coli and S. aureus at logarithmic phase ; however, some of them(proline, glycine, valine and histidine of E. coli and proline, methionine and histidine of s. aureus) were elevated and some other amino acid(aspartic acid, glutamic acid, tyrosine and arginine of E. coli and aspartic acid, glutamic acid, glycine, alanine and lysine of Staph. aureus) found to be decreased. The amount of cell body protein leaked from E. coli and S. aureus increased to 1.02 and 0.22mg/g cell weight, respectively, as compared to controls. Similarly, the substances with absorbance at 260 nm from E. coli and s. aureus increased to 0.12 and 0.06mg/g cell weight, respectively.