• Journal of Food Hygiene and Safety
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• v.30 no.1
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• pp.92-97
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• 2015

The aim of this study is to examine the removal efficiency of pathogen (Escherichia coli O157:H7 and Salmonella typhimurium) on meat and fish products (packing condition: vacuum or not and storage temperature: $4^{\circ}C$ or $-20^{\circ}C$) repeatedly exposed at low-dose gamma irradiation. In case of meat products (beef and chicken), E. coli O157:H7 was not observed at the level of 2 kGy single gamma irradiation and 0.5 kGy repeated gamma irradiation and S. Typhimurium was not observed at the level of 2 kGy single gamma irradiation and 1 kGy repeated gamma irradiation. In case of fish products, E. coli O157:H7 and S. Typhimurium were not detected at the level of 0.5 kGy single and repeated gamma irradiation. These results showed that microorganisms on fish products were more efficiently removed than those of meat products with low-dose gamma irradiation. Generally, each packing condition made no difference. However, the products (fish and meat) stored at $-20^{\circ}C$ needed more higher dose gamma irradiation than products at $4^{\circ}C$.

• Microbiology and Biotechnology Letters
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• v.23 no.6
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• pp.665-670
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• 1995

A marine bacterium which produces extracelluar agarase was isolated from sea water. Isolated strain was identified as Pseudomonas sp. by the morphological and biochemical properties (1). HindIII restriction fragment of 3.2 kb from Pseudomonas genomic DNA was cloned into pUC19 to obtain recombinant plasmid pJA1 which enables E. coli JM83 to produce agarase. Most of agarase produced in E. coli was secreted into the culture medium. The enzyme (pJA1) showed the highest agarase activity during the stationary phase (20 hrs) of E. coli. The optimum temperature and pH were 40$\circ$C and 7.8, respectively. Restriction gene map anlaysis revealed that it has different restriction pattern with three kind of agarase gene reported.

• Journal of Microbiology and Biotechnology
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• v.27 no.6
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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.

• Nutrition Research and Practice
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• v.1 no.4
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• pp.273-278
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• 2007

The objective of this study was to evaluate the inhibitory activity of natural products, against growth of Escherichia coli (ATCC 25922) and Salmonella typhimurium (KCCM 11862). Chitosan, epigallocatechin gallate (EGCG), and garlic were used as natural bioactives for antibacterial activity. The testing method was carried out according to the disk diffusion method. All of chitosan, EGCG, and garlic showed inhibitory effect against the growth of E. coli and Salmonella typhi. To evaluate the antibacterial activity of natural products during storage, chicken skins were inoculated with $10^6$ of E. coli or Salmonella typhi. The inoculated chicken skins, treated with 0.5, 1, or 2% natural bioactives, were stored during 8 day at $4^{\circ}C$. The numbers of microorganisms were measured at 8 day. Both chitosan and EGCG showed significant decrease in the number of E. coli and Salmonella typhi in dose dependent manner (P < 0.05). These results suggest that natural bioactives such as chitosan, EGCG may be possible to be used as antimicrobial agents for the improvement of food safety.

• Journal of Microbiology and Biotechnology
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• v.5 no.6
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• pp.353-358
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• 1995

Escherichia coli causes intestinal and extraintestinal infections and has been an indicator of fecal pollution in water and food. BALB/c mouse was immunized by injection of somatic E. coli (ATCC 8739) cells to produce monoclonal antibodies. Splenocytes of mouse were fused with myeloma cells (Sp2/0-Ag14). Two hybridomas secreting monoclonal antibodies were established after being cloned. In SDS-PAGE analysis of E. coli antigens 37 protein profiles appeared from 14 kDa to 182 kDa. Western blot analysis using polyclonal antibodies demonstrated that protein antigens of 41 kDa, 38.2 kDa and 31.7 kDa were immunodominant. Monoclonal antibodies DY-CM1 and DY-CM2 recognized 31.7 kDa and 2.0 kDa antigens in Western blot analysis, respectely.

• Biotechnology and Bioprocess Engineering:BBE
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• v.3 no.1
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• pp.6-10
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• 1998

A plasmid vector containing two reporter genes, mer-lux and lac-GFP, was transformed to both Escherichia coli and Pseudomonas putida. Their cellular activities and biofilm characteristics were investigated in flow-cell units by measuring bioluminescent lights and fluorescent levels of GFP. Bioluminescence was effective to monitor temporal cell activities, whereas fluorescent level of GFP was useful to indicate the overall cell activities during biofilm development. The light production rates of E. coli and P. putida cultures were dependent upon concentrations of HgCl2. Mercury molecules entrapped in P. putida biofilms were hardly washed out in comparison with those in E. coli biofilms, indicating that P. putida biofilms may have higher affinity to mercury molecules than E. coli biofilms. It was observed that P. putida expressed GFP cDNA in biofilms but not in liquid cultures. This may indicate that the genetic mechanisms of P. putida were favorably altered in biofilm conditions to make a foreign gene expression possible.

• Childhood Kidney Diseases
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• v.16 no.1
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• pp.38-45
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• 2012

Purpose: The incidence of community-acquired urinary tract infection (UTI) due to extended-spectrum ${\beta}$-lactamase producing $Escherichia$ $coli$ (ESBL(+) $E.$ $coli$) has increased worldwide. ESBL causes resistance to various types of the newer ${\beta}$-lactam antibiotics, including the expanded spectrum cephalosporins and monobactams. We aimed to investigate the severity of UTI and associated genitourinary malformations in children with febrile UTI caused by ESBL(+) $E.$ $coli$. Methods: We retrospectively reviewed the medical records of 290 patients diagnosed as febrile UTI caused by $E.$ $coli$ between January 2008 and October 2010 at Korea University Medical center. We classified the patients into two groups with ESBL(+) and ESBL(-) $E.$ $coli$ group according to the sensitivity of urine culture. Fever duration, admission period, white blood cell (WBC) counts and C-reactive protein (CRP) in peripheral blood, the presence of hydronephrosis, cortical defects, vesicoureteral reflux (VUR) and renal scar were compared between the two groups. Results: Patients with ESBL(+) $E.$ $coli$ were 32, and those with ESBL(-) $E.$ $coli$ were 258. If we excluded those tested with a sterile urine bag, patients with ESBL(+) $E.$ $coli$ were 22, and those with ESBL(-) $E.$ $coli$ were 212. Whether the results of sterile urine bag tests were included or not, there was no significant difference in all parameters between the two groups statistically. Conclusion: Our data shows that ESBL(+) $E.$ $coli$ may not be related to the severity of UTI and associated genitourinary malformations.

• The Journal of the Korean Society for Microbiology
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• v.35 no.5_6
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• pp.337-339
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• 2000

MRSA, erythromycin-resistant S. pyogenes, penicillin non-susceptible pneumococci, PPNG, ESBL-producing E. coli and K. pneumoniae, class C ${\beta}$-lactamase-producing E. coli, fluoroquinolone-resistant E. coli, aminoglycoside-resistant A. baumannii and P. aeruginosa are all prevalent in Korea, which suggest the presence of high levels of antimicrobial selective pressure and nosocomial spread of resistant bacteria. Rapid increase of VRE and emergence of fluoroquinolone-resistant gonococci and VIM-2 metallo-${\beta}$-lactamase-producing P. aeruginosa are recently observed new threats in Korea.

• The Journal of the Korean Society for Microbiology
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• v.18 no.1
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• pp.53-58
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• 1983

Enterotoxigenic E. coli is one of causative agents of the infantile diarrhea and traveler's diarrhea. A modified infant mouse assay(IMA) was developed for the detection of heat stable enterotoxin (ST) of E. coli isolated from diarrheal and control infants and assay system was established with using enterotoxin producing reference strains. The supernatant of the 24 hour-shaking culture of E. coli in Casamino Acid Yeast Extract Salt Broth(CYES-2) was ingested orally into the 2-4 day old ICR mice. After the mice were kept at $25^{\circ}C$ for 4 hours, they were sacrificed and the gut weight body weight ratio(GW/BW) was taken as the index of fluid accumulation induced by heat stable enterotoxin of E. coli. The results obtained were as follows; 1. The GW/BW responses of IMA tested with enterotoxin reference strains of E. coli(E. coli O148H28:$ST^+LT^+$, E. coli $O78H^-:ST^+LT^+$, E. coli O15H11:$ST^-LT^+$, E. coli O1H7:$ST^-LT^-$) appeared ta be ST dose-dependent, and not LT-dependent. From the dose-response curve, $25{\mu}l$ of culture supernatant was determined as test amount of the IMA. 2. Frequency distribution of IMA result from 643 strain of E. coli showed normal distribution at low GW/BW ratio and dispersed pattern at high GW/BW ratio. The GW/BW ratios of $0.056{\pm}0.004(mean{\pm}SD)$ of normal distribution which distributed from 0.044 to 0.068(P<0.01) was considered as ST negative. Thus the GW/BW ratio above 0.069 could be regarded as ST positive.

• Biomedical Science Letters
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• v.10 no.3
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• pp.293-298
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• 2004

This study was performed to compare the growth rates, cellular fatty acid compositions and morphology by using electron microscope of Escherichia coli (E. coli) grown in various conditions including different concentrations of phenol, CdCl₂ and HgCl₂. Ninety eight E. coli strains were isolated from Naktong river and human feces. The content of unsaturated fatty acids, especially 16:1ω7c and 18:1ωc increased as the concentration of phenol and CdCl₂ increased. The content of unsaturated fatty acid increased up to 50 ppb of HgCl₂, but decreased at 75 ppb of HgCl₂. There were more unsaturated fatty acids than saturated fatty acid in the presence of toxic substances. However, the ration was reversed when the affected E. coli was transferred to toxic substance free fresh trypticase soy broth medium. Also, by using transmission electron microscope these cells were observed to various morphological deformation by heavy metals and their deposition on the surface. From these results, we suggested that the changes of major fatty acids composition and morphology of E. coli may be considered to indicate contaminated levels of heavy metals or organic solvents. The information presented here may be useful in predicting effects of heavy-metal and organic solvent contamination in streams and provides a basis for further studies of metal or organic solvent effects on microbial communities.