• Korean Journal of Microbiology
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• v.43 no.2
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• pp.116-123
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• 2007

The purpose of this study was typing the plasmid mediated extended spectrum ${\beta}-lactamases$ produced by enteric bacteria isolated from rivers in Pusan. Six strains of Eschericha coli and fifteen strains of Klebsiella pneumoniae transferred their plasmid mediated extended spectrum ${\beta}-lactamase$ genes to the recipient strain Eschericha coli J53 $Azid^{R}$. The plasmid mediated extended spectrum ${\beta}-lactamase$ genes were sequenced directly after PCR and the types were determined by the BCM Search Launcher and GenBank nucleotid database. Determined types of the plasmid mediated extended spectrum ${\beta}-lactamases$ were TEM-52 and SHV-12. TEM-52 was isolated from both Escherichia coli and Klebsiella pneumoniae. However SHV-12 was isolated from Klebsiella pneumoniae only. The results indicated that the plasmid mediated extended spectrum ${\beta}-lactamase$ producing bacteria spreded over the area of clinical to the nature in Korea.

• Journal of Radiation Industry
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• v.5 no.1
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• pp.63-67
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• 2011

A comparative experiment was conducted to compare the effects of persulfate with gamma radiation on the disinfection efficiencies against Escherichia coli K12. The microorganism used for the disinfection experiments were prepared by transferring a bacterial stock culture into a 50 ml nutrient broth an incubating for 24 hrs at $37^{\circ}C$. The initial concentration of the harvested culture was approximately $10^7$ to $10^9CFU\;ml^{-1}$. The culture solution was irradiated at different absorbed doses of 0.1, 0.2, 0.3, 0.4, 0.5, 0.7, and 1 kGy, respectively. The disinfection efficiency of persulfate with gamma radiation of 0.3 kGy against Escherichia coli K12 was 97.2% and while the gamma radiation only was 90.01% at 0.3 kGy. Therefore, it could be thought that addition of persulfate in the disinfection of Escherichia coli K12 can enhance the disinfection efficiency when it is used together with gamma radiation.

• Journal of Life Science
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• v.20 no.5
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• pp.676-682
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• 2010

This study focused on typing of the extended-spectrum $\beta$-lactamase (ESBL) produced in organisms isolated from a natural environment, rather than a clinical setting. Samples were collected from drain water issuing from a sewage plant in Kwanganri (Busan, Korea). Following double disk synergy testing, 29 strains were selected as potential ESBL positive strains. Of these, 15 strains were transconjugants of the sodium azide resistant recipient strain Escherichia coli J53 and analyzed biochemically including indole, methyl-red, Voges-Proskauer, Simmon's citrate, decarboxylase-dihydrolase and sugar-fermentation tests. The tests classified the 15 strains as Klebsiella pneumoniae (n=13) and Escherichia coli (n=2). The type of ESBL from each strain was deduced by isoelectric focusing point analysis and DNA sequencing. The results indicated that the types of ESBL were SHV-12 (n=4) and SHV-12/TEM-1 (n=9) from K. pneumoniae and TEM-1 (n=2) from E. coli strains.

• The Korean Journal of Food And Nutrition
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• v.19 no.4
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• pp.526-531
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• 2006

Minimum inhibition concentration(MIC), growth inhibition activity, and colony forming inhibitory activity of grapefruit seed extract against Bacillus cereus, Bacillus subtilis, Listeria monocytogenes, Escherichia coli, Salmonella enterifidis and Serratia marcescens were tested. MIC of grapefruit seed extract against Bacillus cereus, Bacillus subtilis, Listeria monocytogenes, Escherichia coli, Salmonella enteritidis and Serratia marcescens was 12.5, 12.5, 12.5, 50, 50, 100ppm, respectively. Growth inhibition concentration of grapefruit seed extract against Bacillus cereus, Bacillus subtilis, Listeria monocytogenes, Escherichia coli, Salmonella enteritidis and Serratia marcescens was below 1.0, 6.25, below 1.0, 6.25, 25, 25ppm, respectively. Colony forming inhibitory activity of grapefruit seed extract against Bacillus cereus, Bacillus subtilis, Listeria monocytogenes, Escherichia coli, Salmonella enteritidis and Serratia marcescens was 93.9, 94.0, 99.9, 4.4, 82.7, 86.4%, respectively. Colony forming inhibitory activities of grapefruit seed extract against Gram positive bacteria were higher than that against Gram negative bacteria.

• Biomolecules & Therapeutics
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• v.12 no.3
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• pp.179-184
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• 2004

The FimH subunit of type 1-fimbriated Escherichia coli has been determined as a major cause for urinary tract infections. In our previous study, the Adhesin/CTXA2B was expressed as soluble recombinant chimaeric protein derived from the uropathogenic Escherichia coli adhesin genetically coupled to cholera toxin A2B (CTXA2B) subunit in Escherichia coli. Since it is very important to optimize IPTG concentration and culture temperature to maximize cell growth and productivity, These optimal culture factors were determined to increase the productivity of the expressed Adhesin/CTXA2B chimaeric protein in Escherichia coli TB1 carrying pMALfimH/ctxa2b. Our data demonstrate that optimal concentration of IPTG for increased production of chimaeric protein was 0.5 mM. Additionally, culture time was 10 hours and temperature, 37${\circ}C$.

• Journal of Microbiology and Biotechnology
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• v.27 no.11
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• pp.2028-2036
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• 2017

The Escherichia coli K-12 and B strains are among the most frequently used bacterial hosts for scientific research and biotechnological applications. However, omics analyses have revealed that E. coli K-12 and B exhibit notably different genotypic and phenotypic attributes, even though they were derived from the same ancestor. In a previous study, we identified a limited number of proteins from the two strains using two-dimensional gel electrophoresis and tandem mass spectrometry (MS/MS). In this study, an in-depth analysis of the physiological behavior of the E. coli K-12 and B strains at the proteomic level was performed using six-plex isobaric tandem mass tag-based quantitative MS. Additionally, the best lysis buffer for increasing the efficiency of protein extraction was selected from three tested buffers prior to the quantitative proteomic analysis. This study identifies the largest number of proteins in the two E. coli strains reported to date and is the first to show the dynamics of these proteins. Notable differences in proteins associated with key cellular properties, including some metabolic pathways, the biosynthesis and degradation of amino acids, membrane integrity, cellular tolerance, and motility, were found between the two representative strains. Compared with previous studies, these proteomic results provide a more holistic view of the overall state of E. coli cells based on a single proteomic study and reveal significant insights into why the two strains show distinct phenotypes. Additionally, the resulting data provide in-depth information that will help fine-tune processes in the future.

• Korean Journal of Microbiology
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• v.45 no.2
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• pp.163-169
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• 2009

This study was performed to investigate the type of extended-spectrum $\beta$-lactamases (ESBL) produced by bacteria isolated from the sewage of wastewater treatment plant at Minragdong, Suyong-gu in Busan. The facility is located at sushi restaurants and guides its drain water to the wastewater treatment plant at Yonghodong, Nam-gu in Busan. Samples were collected on January, 2009. A total of 19 strains were selected as potential ESBL positive strains through a double disk synergy test. On the basis of the results from biochemical tests including indole, methyl-red, Voges-Proskauer, Simmon's citrate, decarboxylase-dihydrolase and sugar-fermentation tests, the 19 strains were identified with 16 strains of Escherichia coli and 3 strains of Klebsiella pneumoniae. Out of 19 strains, 4 transconjugants against Escherichia coli J53, which is sodium azide resistant recipient strain, were obtained. The plasmids isolated from transconjugants were used for PCR analysis. The type of each extended-spectrum $\beta$-lactamase (ESBL) produced by the strains was determined on the basis of isoelectric focusing analysis and DNA sequencing. The results indicated that the types of ESBL from Klebsiella pneumoniae were SHV-12 (3 strains), and Escherichia coli was SHV-12/TEM-1 (1 strain), respectively.

• Biomedical Science Letters
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• v.17 no.1
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• pp.7-12
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• 2011

Free-living amoebae ingest several kinds of bacteria. In other words, the bacteria can survive within free-living amoeba. To determine how Escherichia coli K1 isolate causing neonatal encephalitis and non-pathogenic K12 interact with free-living amoebae, e.g., Acanthamoeba castellanii (T1), A. astronyxis (T7), Naegleria fowleri, association, invasion and survival assays were performed. To understand pathogenicity of free-living amoebae, in vitro cytotoxicity assay were performed using murine macrophages. T1 destroyed macrophages about 64% but T7 did very few target cells. On the other hand, N. fowleri which needed other growth conditions rather than Acanthamoeba destroyed more than T1 as shown by lactate dehydrogenase (LDH) release assay. In association assays for E. coli binding to amoebae, the T7 exhibited significantly higher association with E. coli, compared with the T1 isolates (P<0.01). Interestingly, N. fowleri exhibited similar percentages of association as T1. Once E. coli bacteria attach or associate with free-living amoeba, they can penetrate into the amoebae. In invasion assays, the K1 (0.67%) within T1 was observed compared with K12 (0%). E. coli K1 and K12 exhibited high association with N. fowleri and bacterial CFU. To determine the fate of E. coli in long-term survival within free-living amoebae, intracellular survival assays were performed by incubating E. coli with free-living amoebae in PBS for 24 h. Intracellular E. coli K1 within T1 (2.5%) and T7 (1.8%) were recovered and grown, while K12 were not found. N. fowleri was not invaded and here it was not recovered.

• Korean Journal of Microbiology
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• v.26 no.2
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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.

• The Korean Journal of Food And Nutrition
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• v.6 no.3
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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.