• Korean Journal of Veterinary Research
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• v.53 no.4
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• pp.199-205
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• 2013

Avian pathogenic Escherichia coli (APEC) is a causative agent for a number of extra intestinal diseases and account for significant losses to the poultry industry. Since protective immunity against APEC is largely directed to virulence antigens, we have individually expressed four different viulence antigens, papA, papG, IutA, and CS31A, using an attenuated Salmonella Typhimurium and a plasmid pBB244. Following oral immunization of mice with combination of two or four of these strains, serum IgG and mucosal IgA responses were elicited against each antigen represented in the mixture. The antigen-specific mucosal IgA responses were significantly higher in the group of mice immunized with the heat-labile Escherichia coli enterotoxin B subunit (LTB) strain than those in the group of mice immunized without the LTB strain. While, there was no significant difference between these two groups in antigen-specific serum IgG responses. The results showed that LTB could act as mucosal immune adjuvant. To assess the nature of immunity, the distribution of antigen-specific IgG isotypes was analyzed. All groups promoted Th1-type immunity as determined by the IgG2a/IgG1 ratio. Thus, our findings provided evidence that immunization with a combination of several vaccine strains is one of the strategies of developing effective vaccines against APEC.

• Korean Journal of Veterinary Research
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• v.38 no.1
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• pp.173-181
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• 1998

Esherichia coli O157 : H7의 slt I, slt II, uid A 및 eaeA 4종 유전자를 동시에 검출하기 위한 multiplex PCR 기법을 확립하고 쇠고기중 직접 E coli O157 : H7 검출시험을 실시하였다. 4 set의 primers를 이용한 multiplex PCR 기법으로 31종의 장내세균에 대한 특이성을 조사한 결과 E coli O157 : H7 에서 1,087bp (eae A), 584bp (slt II), 348bp (slt I) 또는 252bp (uid A)크기의 DNA를 동시에 특이적으로 검출할 수 있었다. E coli O157 : H7 15주는 모두 uid A 및 eae A 유전자가 동시에 검출되었고, 다른 장내세균에서는 검출되지 않았다. slt I 또는 slt II 유전자를 가지고 있는 E coli 표준균주 24종을 이용하여 multiplex PCR 기법과 Vero cell cytotoxicity assay을 비교검사한 결과 베로톡신 산생능과 PCR법의 결과는 일치하였다. mutiplex PCR 기법의 쇠고기중 검출한계는 modified EC(mEC)에서 증균없이는 E coli O157 : H7균 $10^4cells/g$ 이상에서 검출이 가능하였으나 mEC에 1차 증균후 modified TSB 증균하였을 경우에는 10cells/g이하까지도 검출이 가능하였다. 개발된 multiplex PCR 기법을 쇠고기 40종에 직접 적용한 결과 E coli O157 : H7은 검출되지 않았으나 slt I 및 slt II유전자를 가지고 있는 E coli 4종이 검출되었으며, 이들의 혈청형은 O6, O112, O115 및 O139 였다. 이 연구에서 개발된 multiplex PCR은 쇠고기중 E coli O157 : H7을 신속하고 특이적으로 검출하는데 사용할 수 있을 것으로 사료된다.

• Korean Journal of Microbiology
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• v.28 no.2
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• pp.109-113
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• 1990

The mutagenesis-enhancing plasmid pKM101 and its mutant pSL4 were introduced into Escherichia coli B/r strains possessing different DNA repair capacities ($phr^{-}, recA^{-}, uvrA^{-}, uvrB^{-}$) and determined the protection effect and mutagenecity for UV and MNNG. The mutability and protection effect of plasmid pKM101 and pSL4 were affected by different DNA repair capacity. The mutagenecity and resistance of two plasmids were increased against UV and MNNG, and plasmid pSL4 had a higher effect than pKM101. We suggest that the functional differences between pKM101 and pSL4 is due to the variety of mutator gene.

• The Journal of the Korean Society for Microbiology
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• v.22 no.2
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• pp.131-137
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• 1987

The incidnce of enterotoxigenic Esherichia coli(ETEC) was investigated in E. coli strains isolated from Korean infants less than two years old. Over a period of 12 months, ETEC strains have been isolated from 45(45.0%) of 100 children with acute diarrhea and from 9(20.5%) of 44 children without diarrhea. In the group with diarrhea, 41(41.0%) strains produced heat-stable toxin, 3(3.1%) produced heat-labile toxin, and 1(1.0%) produced both heat-stable and heat-labile toxins. In the control group, 7(15.9%) released heat-stable toxin, 2(4.5%) released heat-labile toxin and none released both. A statistical association of strains releasing heat-stable toxin was significant(P<0.025).

• Korean Journal of Food Science and Technology
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• v.53 no.6
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• pp.819-822
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• 2021

To enhance phage endolysin-mediated cell wall disruption of Escherichia coli O157:H7, the cells were co-treated with aromatic compounds, namely thymol or eugenol, found in essential oils and endolysin LysECP26. Interestingly, the minimal inhibitory concentrations of LysECP26 was four times lower when used in combination with either of the two compounds than when it was used alone. This synergistic activity was also confirmed by viable cell counting. Within 1 h of LysECP26 and eugenol or thymol co-treatment to the cells, there was a 2.3 or 3.8 log CFU/mL reductions, respectively. Additionally, field emission scanning electron microscopy showed cell wall disruption and severe morphological alterations of the cells in case of the combination treatments. Therefore, endolysin and thymol or eugenol co-treatment can help in developing efficient bio-control strategies against gram-negative pathogen E. coli O157:H7.

• Korean Journal of Microbiology
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• v.34 no.4
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• pp.248-253
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• 1998

Bacteriophage N4, a lytic phage specific for Esherichia coli K12 strain encodes single-stranded DNA-binding protein, N4SSB (bacteriophage N4-coded single-stranded DNA-binding protein). N4SSB protein is originally identified as a protein required for N4 DNA replication. N4SSB protein is also required for N4 late transcription, which is catalyzed by E. coli ${\sigma}^{70}$ RNA polymerase. N4 late transcription does not occur until N4SSB protein is synthesized. Recently it is reported that N4SSB protein is essential for N4 DNA recombination. Therefore N 4SSB protein is a multifunctional protein required for N4 DNA replication, late transcription, and N4 DNA recombination. In this study, a variety of mutant N4SSB proteins containing internal deletions or substitutions were constructed to define and characterize domains important for N4 DNA replication, late transcription, and N4 DNA recombination. Test for the ill vivo activity of these mutant N4SSBs for N4 DNA replication, late transcription, and N4 DNA recombination was examined. The results suggest that C-terminal 7 amino acid residues are important for the activity of N4SSB. Three lysine residues, which are contained in this region play important roles on N4SSB activity.

• Fisheries and Aquatic Sciences
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• v.2 no.1
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• pp.93-97
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• 1999

The promoter region of alginate lyase gene (aly) from Pseudomonas sp. W7 was used for the high expression of gilthead seabream (Sparus aurata) growth hormone (GH) gene in Esherichia coli. PCR product encoding the premature segment of the growth hormone. was cloned to the downstream of aly promoter. GH was overexpressed With 46 ammo acid of alginate lyase as fusion protein. GH was immunoreactive and production of GH was repressed with supplementation of $0.4\%$ glucose into culture media.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.202-205
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• 2000

A gene coding $endo-{\beta}$,-1, 4 glucanase from Actinomyces sp. KNG40 and phytase from Hansenula polymorpha were cloned into Esherichia coli JM101 by using E. coli/Lactobacillus shuttle vector pNZ3004 and pNZ123. The plasmid p3PS(1-4) and p123(1-4) have slpA promoter and slpA signal sequence. So, I constructed expression vectors, p3PS(1-4)Endo, phy and p123(1-4)Endo, phy. These constructed vector was transformed in target host Lactobacillus gasseri and reutri. These transformed host expressed endoglucanase and phytase as extracellular fraction. In the enzyme activity of the same vector, host L, gasseri was higher activity than L. reuteri. This indicates that L. gasseri recongnize promoter and signal sequence very well.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.174-174
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• 2012

The nature of feed gas is essential for the active species formed in the nonthermal plasma jets, which would induce various biological phenomena. We investigated the different physiological effects of atmospheric pressure soft-plasma jets on Esherichia coli and blood cells according to the feed gas. Cell death rate, growth curve, membrane molecular changes and induced genes were examined. The relationship between cellular reactions and active species generated by discharge will be discussed.

• Fisheries and Aquatic Sciences
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• v.7 no.2
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• pp.64-69
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• 2004

A bacteriological survey for 20 large grocery stores (M 1 to M20) in Korea was investigated for one year. The average detection rate of Esherichia coli was $22\%$ (166/763) for 7 kinds of ready-to-eat food through the year, where each grocery store and each type of food showed different detection rates. Eleven grocery stores showed lower detection rates, while 9 grocery stores showed a higher than average rate. Especially, M3 showed a rate that was twice as high as the average and one which was 7 times higher than M14, which had the lowest rate of $6\%$ E. coli detection. The detection rate for each type of food was: $38\%$ (41/109) for Kimbop, $31\%$ (34/109) for vegetable salad, $19\%$ (21/109) for bean-curd, $18\%$ (20/109) for the cooked materials used in making Kimbop, $17\%$ (19/109) for Hoe (sliced raw fish) and Sushi (Japanese vinegared rice delicacies), and $11\%$ (12/109) for cooked pork hock. During the summer, the E. coli detection rate averaged $43\%$ (71/166), which was twice as high as other seasons. Most (89/100) of the food contacting surfaces contained more than the critical limit $(1.3\;log_{10}\;CFU/10cm^2)$ of aerobic viable cell counts (AVC). The $log_{10}$ AVC and $log_{10}$ coliform count (CC) of 218 meat samples (beef, pork, and chicken) ranged between 4.6-7.1 CFU/g and 1.9-6.4 CFU/g, except for 41 meat samples $(19\%)$ which were found to contain no coliform. There was a definite correlation between the $log_{10}$ AVC and $log_{10}$ CC, and the values of $log_{10}$ CC made a more accurate straight than the $log_{10}$ AVC, which are variable. From these results, it is suggested that a detection rating of less than 2.1 CFU/g of $log_{10}$ CC (correspond to 5.0 CFU/g of $log_{10}$ AVC) is the critical point of freshness, and a rating of more than 6.3 CFU/g of $log_{10}$ CC (correspond to 7.0 CFU/g of $log_{10}$ AVC) can be considered an initial spoilage point.