• 한국식품위생안전성학회지
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• 제12권1호
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• pp.78-82
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• 1997

Surface swab samples from beef (188), pork (240) and chicken (95) carcasses were collected from slaughterhouse in Kangwon and Kyunggi areas from March through July 1996. The samples were examined on the level of E. coli biotype I relevant to fecal contamination due to unsanitary processing control and the existence of verocytotoxin-producing E. coli (VTEC). E. coli biotype I were confirmed from 38.8% of beef, 40.0% of pork, and 69.5% of chicken carcasses. Little variation was noted among three sampling points; rump, flank and neck of beef, ham, belly and jowls of pork. coli O157:H7 was only confirmed from 2 of 188 beef carcasses. E. coli biotype I. All the isolated E. coli O157 showed positive for vero cell cytotoxicity test. Isolation rate of E. coli O157 in summer was higher than in spring. In case of pork and chicken carcasses, E. coli O157 was isolated in summer only.

• 미생물학회지
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• 제26권2호
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• pp.113-121
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• 1988

Ozone, an atmospheric pollutant, can damage similar UV and X-rays DNA and its components. It is possible then that the KNA damage produced by this gas are similar, to some extent, to those of radiations and that they could be repaired by the same DNA repair mechanisms. It has been observed in Escherichia coli that radiosensitive strains such as lex A, rec A and pol A, all deficient to some extent for DNA repair, are more sensitive to ozone than a wild type strain. We have thendetermined the ozone resistance and host-cell reactivation of ozone-damaged T3 phages for the E. coli double mutants pol A, lex A, uvr B, lex A, uvr A, rec A and rec A lox A. According to the results, the DNA polymerase 1 plays a key role in ozone resistance and Type 11 mechanism and/or shory patch excision repair are the most important for it. The interactions between the different DNA repair mechanisms are secondary. There is a strong correlation between ozone resistance and the capacity to reactivate T3 phages damaged by ozone.

• Journal of Microbiology and Biotechnology
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• 제15권6호
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• pp.1346-1352
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• 2005

We have developed a modified gene replacement method using PCR products containing short homologous sequences of 40- to 50-nt. The method required $\lambda$-Red recombination functions provided under the control of a temperature-sensitive CI857 repressor expressed from the $P_{lac}$ promoter in the presence of IPTG on an easily curable helper plasmid. The method promoted the targeted gene replacements in the Escherichia coli chromosome after shifting cultures of the recombinogenic host, which carries the helper plasmid, to $42^{\circ}C$ for 15 min. Since this method employs $\lambda$-Red recombination functions expressed from the easily curable helper plasmid, multiple rounds of gene replacements in the E. coli chromosome would be possible. The procedures described herein are expected to be widely used for metabolic engineering of E. coli and other bacteria.

• Journal of Microbiology and Biotechnology
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• 제24권9호
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• pp.1232-1237
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• 2014

Lycopene, which is a well-known red carotenoid pigment, has been drawing scientific interest because of its potential biological functions. The current study reports that lycopene acts as a bactericidal agent by inducing reactive oxygen species (ROS)-mediated DNA damage in Escherichia coli. Lycopene treatment elevated the level of ROS-in particular, hydroxyl radicals ($^*OH$)-which can damage DNA in E. coli. Lycopene-induced DNA damage in bacteria was confirmed and we also observed cell filamentation caused by cell division arrest, an indirect marker of the DNA damage repair system, in lycopene-treated E. coli. Increased RecA expression was observed, indicating activation of the DNA repair system (SOS response). To summarize, lycopene exerts its antibacterial effects by inducing $^*OH$-mediated DNA damage that cannot be ameliorated by the SOS response. Lycopene may be a clinically useful adjuvant for current antimicrobial therapies.

• Journal of Microbiology and Biotechnology
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• 제27권6호
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• pp.1106-1111
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• 2017

Escherichia coli was engineered to sense methanol by employing a chimeric two-component system (TCS) strategy. A chimeric MxaY/EnvZ (MxaYZ) TCS was constructed by fusing the Paracoccus denitrificans MxaY with the E. coli EnvZ. Real-time quantitative PCR analysis and GFP-based fluorescence analysis showed maximum transcription of ompC and the fluorescence at 0.01% of methanol, respectively. These results suggested that E. coli was successfully engineered to sense methanol by the introduction of chimeric MxaYZ. By using this strategy, various chimeric TCS-based bacterial biosensors can be constructed and used for the development of biochemical-producing recombinant microorganisms.

• 한국동물위생학회지
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• 제30권1호
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• pp.103-113
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• 2007

We monitored antibiotic resistance of Escherichia coli isolates from healthy volunteers of community and chicken butchers from February to July in 2006. From disc diffusion test on 473 E coli isolates from healthy volunteers of the community, the resistance rates of tetracycline, ampicillin, and ticarcillin were 44.8%, 40.8%, and 37.4%, respectively. In the disc diffusion test on 18 E coli isolates from chicken butchers, the resistance rates of tetracycline, nalidixic, streptomycin, and ampicillin were 94.4%, 61.1%, 55.6%, and 50.0%, respectively.

• 대한수의학회지
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• 제55권1호
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• pp.41-46
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• 2015

Increasing presence of wild boar around cities and suburban areas is a growing concern with respect to agronomy, environmental ecology, and public safety. In this study, antibiotic resistance profiles of Escherichia (E.) coli isolated from wild boar and domestic pig fecal samples were compared. Eighty E. coli samples were isolated from wild boars. Resistance of the bacteria to 14 common antimicrobial agents used in human and veterinary medicine was evaluated. Ninety-five E. coli isolates from domestic pig farms were used for comparison. Common and distinct antibiotic resistance patterns were observed when comparing wild boar and domestic pig isolates, indicating that wild boars may significantly influence environmental microbiology.

• 대한수의학회지
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• 제17권1호
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• pp.1-4
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• 1977

Two hundred and twenty-seven strains of Escherichia coli isolated from 25 hens (12 hens received tetracycline neomycin and sulfadimethoxine, and 13 hens not received antibiotics) were studied for the drug resistance and distribution of R factors. About 74 per cent of E. coli strains isolated from hens of a herd received antibiotics were resistance to tetracycline (TC) streptomycin (SM), chloramphenicol (CM), kanamycin (KM), ampicillin (AP) and sulfisomidine (Su), alone or in combination thereof, but only a hen among a herd not received antibiotics excreted E. coli resistant to TC and SM. Among resistant strains, about 7% were found to be resistant to TC and SM, whereas 93% were resistant to three or more antibiotics. The most common pattern was the quadruple resistant to SM, TC, KM and Su (28.7%), and followed by triple ones to SM, TC and Su (25.3%), and SM, TC and KM (24.7%). About 84% of resistant strains carried R factors which were transferable to the recipient by conjugation.

• 한국식품영양학회지
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• 제6권3호
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• pp.169-177
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• 1993

The conversion of glutamate by glutamine synthetase Is the endergonic reaction that demands ATP as its energy source. In order to supply efficiently ATP that is demanded in the conversion of glutamate to glutamine, the ATP- generating system by acetate kinase partially purified from Escherichia coli K-12 was coupled with glutamine synthetase partially purified 5. coli K-12 Pgln6. The optinum conditions of the coupled reaction were investigated. As the result, the highest conversion of glutamate to glutamine was shown In the reaction mixture containing 100mM glutamate, 100mM NHtCl, 50M acetyl phosphate, 5mM ADP, 40M MgCl2, 300mM potassium phosphate buffer (pH 7.5), 5mM MnCl2, Under this condition, the most effective concentrations of enzyme were 70unit/ml glutamine synthetase and 99unit/ml acetate kinase. Under the optinum conditions, 98% of 100mM glutamate was converted to glutamine within 6 hours.

• Journal of Yeungnam Medical Science
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• 제30권2호
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• pp.83-89
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• 2013

Background: The prevalence of extended-spectrum ${\beta}$-lactamase (ESBL)-producing Escherichia coli is increasing rapidly worldwide. Treatment options for ESBL-producing E. coli are limited, and infections caused by this organism are associated with improper antibiotic use, a long hospital stay, and increased mortality. Thus, the assessment and early recognition of the risk factors of nosocomial infections due to ESBL-producing E. coli are important for the infection control and proper treatment. Methods: A case-control study was performed that included nosocomial episodes of ESBL-producing E. coli bacteremia at a tertiary care hospital from January 2004 to December 2007. For each case patient, three controls were randomly selected and data on predisposing factors were collected. Results: Fifty-five cases of nosocomial ESBL-producing E. coli bacteremia were studied. Carbapenem usage (OR: 11.3, 95% CI: 1.1-115.9, p=0.041), quinolone usage (OR: 4.5, 95% CI: 1.1-18.8, p=0.042), biliary obstructive disease (OR: 11.8, 95% CI: 3.0-46.7, p<0.001) and the APACHE II score (OR: 1.3, 95% CI: 1.2- 1.5, p<0.001) were analyzed as independent risk factors of nosocomial ESBL-producing E. coli bacteremia. Conclusion: Our results showed that physicians caring for patients with risk factors of nosocomial bacteremia should consider ESBL-producing E. coli as the causative organisms of the disease.