• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.6
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• pp.1173-1176
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• 1998

Glycogen synthetase[EC 2.4.1.21] in E. coli B was isolated and purified by sonication, ultracentri fugation, DEAE cellulose chromatography and gel chromatography. In the case of using glycogen or maltotriose as a primer in the enzyme reaction, 64% and 23.7% of labelled ADP glucose were incorporated into primer, respectively. 8.1% of labelled ADP glucose was polymerized into glycogen in enzymatic reaction without a primer.

• Journal of Microbiology
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• v.40 no.2
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• pp.98-103
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• 2002

Twenty-eight clinical isolates of Escherichia coil, composed of thirteen norfloxacin resistant isolates (MIC of >16${\mu}$g/ml), one intermediately resistant isolate (MIC of 8${\mu}$g/ml), and fourteen susceptible isolates (MIC of <4${\mu}$g/ml), were randomly selected to study the norfloxacin resistance mechanism and phylogeny in clinical isolates in Korea. Eleven nofloxacin resistant isolates and one susceptible isolate were multi-drug resistant (MDR). Every norfloxacin resistant isolate with MIC higher than 32${\mu}$g/ml had the same three mutations: Ser83\longrightarrowLeu and Asp87\longrightarrowAsn or Tyr in GyrA and Ser80\longrightarrowIle in ParC. Whereas a resistant isolate with MIC of 16${\mu}$g/ml had three mutations but Asp87 in GyrA was replaced with Gly instead of Asn. The intermediately resistant isolate had the same two mutations in GyrA but a different mutation in ParC, Glu84\longrightarrowLys. Among the susceptible isolates, two isolates with MIC of 4${\mu}$g/ml had one mutation: Ser83\longrightarrowiLeu in GyrA, and no mutation was found in the susceptible isolates. Resistant isolates showed higher efflux activity than the susceptible ones, with random amplification of polymorphic DNA (RAPD), six susceptible isolates form a separate group from the rest of the isolates.

• The Korean Journal of Zoology
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• v.38 no.4
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• pp.565-569
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• 1995

We have previoosly demonstrated that the RecA-like protein of Schizosaccharomyces pombe (S. pombe) is immunologically related to Escherichia coil (E. coil) RecA protein and that the cellular level of the protein is significantly increased by inhibitors of nucleotide pool-forming enzymes such as hydroxyurea (HU) and methotrexate (MTX) (lee and Park, 1994; lee et al., 1994). In this study, we report that the ribonudeotide redudase activity of S. pombe is inhibited by E. coil RecA antibody, as determined by thin layer chromatography using [5-$^3$H]CDP as a substrate. The relative activity of ribonucleotide reductase was dramatically inhibited by 100 mM of flu (26.4% reduction) in in vitro assay, compared to that of non-treated control. The ribonucleotide reductase activity was also inhibited by immunoprecipitation with E. coil RecA antibody (43.3% reduction). These results indicate that the strudure of S. pombe ribonucleotide reductase is in part similar to that of E. coil RecA protein.

• Korean Journal of Veterinary Service
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• v.15 no.2
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• pp.134-143
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• 1992

The present study was conducted to investigate the biochemical characteristics and anti-biotic resistance of Escherichia coli(E. coli) isolated from piglets with diarrhea in Kyongbuk province during the Period from February to November 1991. 368 E. coli strains were isolated from 382 piglets with diarrhea and the biochemical and cultural reaction were compared with the classification criteria of Edwards and Ewing. Tetracycline and sulfadimethoxine were found to be highly ineffective at in vitro inhibition of the E. coli of piglets origin. The majority of E. coli were susceptible to amikacin, chloramphenicol and gentamicine. 89 (89.0%) of 100 strains of E. coil were resistant to one or more drugs. The organisms resistant to 20 or 3 drugs were 54(60.6%) of 89 strains, whereas 16(17.9%) strains were found to be resistant to one drug. 55(61.8%) out of 89 drug resistance strains carried R factors($R^+$) which were transfer-able to the recipients by conjugation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.5
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• pp.1344-1348
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• 2008

Anti-microbial activities of Scutellariae Radix Extracts and Sophora flavecens Extracts was tested by formulation, such as skinsoftener, emulsion for 4 weeks. Control contained no preservative, test group contained 1.00% Scutellariae Radix extracts and 1.00% Sophora flavecens extracts and positive control contained parabens and imidazolidinyl urea. To determine the anti-microbial activity of these extract, the 4 germs such as Escherichia coil, Pseudomonas aeruginosa, Staphylococcus aures, Canida albicans were used. The test groups showed significant anti-microbial activities against the 4 germs at 2 and 3 weeks as compared with control. Anti-microbial activities of these extracts were similar to positive control. Considering that the Scutellariae Radix Extracts and the Sophora flavecens Extracts have a significant anti-microbial activities against 4 germs, it is possible as natural preservative in cosmetics.

• Journal of Microbiology
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• v.40 no.2
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• pp.91-97
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• 2002

Enteroaggregative E. coil (EAEC) is an important aethiological causal agent of diarrhea in people of developed and undeveloped countries. Different in vitro and in vivo models have been proposed to study the pathdgenic and immune mechanisms of EAEC infaction. The aim of this study was to analyze whether BALB/c mice could be used as an animal model to study EAEC pathogenesis Six-week-old BALB/c mice were inoculated with EAEC strain 042 (044:H88) nalidixic acid resistant, and re-inoc-ulated ten days after. Mice feces were monitored for the presence of the EAEC strain over a period of 20 days . Bacteria were enumerated on MacConkey agar containing 100$\mu$g of nalidixic acid per ml. Results showed that 35% of the animals were colonized for 3 days, 15% for 5 and 10% for more than 7 days . After re-inoculation only 16% of the animals remained colonized for more than 3 days. During the necropsy, the intestinal fluid of same of the infected animals presented mucus and blood. Six of these fluids showed the presence of IgA antibodies againset Pet toxin and IgG natibodies raised against the toxin were also detected in the animal serum. Histopathologic evidence confirms the stimulation of mucus hypersecretion, an increased amount of goblet cells and the presence of bacterial aggregates in the apical surfaces of intestinal epithelial cells. Edema was present in the submucosa. These results suggest that BALB/c mice could be used as an animal model for in vivo study of EAEC infection.

• Korean Journal of Veterinary Research
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• v.36 no.2
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• pp.379-387
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• 1996

The objects of the present study were to establish the method of purification, subunit dissociation of verotoxin-2 (VT2) produced by Escherichia coli O157:H7, and to investigate the characteristics of purified verotoxin-2 such as molecular weight and composition of amino acid. The results were summerized as follows; Verotoxin-2 was extracted by addition of polymyxin B sulfate into bacterial cell lysate prepared from Escherichia coli O157:H7(KSC109). As an initial step, the bacterial cell lysate was precipitated with 30% saturated ammonium sulfate. The precipitated crude toxin was then subjected to anion-exchange, chromatofocusing and cation-exchange chromatography. Using this scheme, we obtained highly purified toxin with a specific activity of $1.1{\times}10^9$ $CD_{50}/mg$. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE) for purified VT2 showed two protein bands. The upper band, approximately 32 Kd, was supposed as A subunit and the lower band, approximately 7.7 Kd, was supposed as B subunit. When the toxin was separated in the subunit-dissociating solution, two peaks emerged with retention times of 15 and 28 min by HPLC. These peaks represented A subunit and B subunit, respectively. The amino acid composition of purified VT2 were made up in order of glutamic acid, histamine, asparaginic acid, histidine, lysine, alanine and leucine etc. The largest amount among the amino acid composing VT2 was methionine.

• Korean Journal of Food Science and Technology
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• v.32 no.1
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• pp.218-224
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• 2000

The antimicrobial activities of chitosan oligosaccharide(chitohexaose) and two types of chitosans M.W.(10,000 and M.W. 100,000) were examined against Escherichia coli O157 : H7(ATCC 43894), Staphylococcus aureus(ATCC 144458) and Candida albicans(KFRI 432). Chitosan with molecular weight of 10,000 showed the strongest antimicrobial activities to E. coil O157 : H7 and S. aureus, whereas chitohexaose acted most strongly against C. albicans. The most effective concentration of chitosan was measured to be 0.1 mg/mL for E. coil O157 : H7 and S. aureus, and that of chitohexaose to be 1 mg/mL for C. albicans. Antimicrobial activities of chitosans and chitohexaose were maintained for 60 min after their treatment. They were found to induce leakage of intracellular proteins and nucleic acids from treated microorganisms. The efflux determined by assaying the ${\beta}-galactosidase$ leaked from the lactose-induced E. coli O157 : H7 cells was observed to reach the highest level within 60 min after treatment with the antimicrobial agents and chitosan with 10,000 molecular weight gave the highest ${\beta}-galactosidase$ activity. Therefore, it is supposed that the antimicrobial activity of chitosan with its unique polycationic nature might be caused by its binding to anionic component(s) of the cell envelope and thereby inhibiting the membrane metabolism and/or leaking intracellular materials.

• Korean Journal of Veterinary Research
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• v.26 no.1
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• pp.69-77
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• 1986

The purpose of this study was the examination for presence of K99 antigen (K99), enterotoxigenicity, 0-groups, colicin and antibiotic susceptibility among E. coil isolated from calves and cows. A total of 49(18.7%) among 262 strains, isolated from 30(26.5%) out of 113 calves and cows, possesed K99, and thirty three of 49 $K99^+$ strains produced ST. Of the strains of diarrheal calf origin which less than 15 days old, a high correlation was observed between enterotoxigenic ability and K99: 92.3% of the $K99^+$ strains produced heat stable enterotoxin(ST). In O group typing of 33 $ST^+$ strains, they belonged to O20(48.4%), O8(9.1%), O9(6.1%), O139(6.1%), O149(6.1%), O101(3.0%), O115(3.0%), except six which were untypable or autoagglutinable. Of 262 E. coil isolates, 30 strains(13.3%) produced colicin and K99 were detected in 6 strains. One hundred eighty eight strains(71.8%) of 262 E. coil isolates were resistance to ampicillin, chloramphenicol, gentamicin, kanamycin, streptomycin, tetracycline, alone or in combination thereof. One hundred and fourteen(60.6%) out of 188 drug resistance strains carried R factor($R^+$) which were transferable to the recipients by conjugation. Sixty five $R^+$ strains(57.0%) carried thermo-sensitive R plasmid.

• Korean Journal of Veterinary Research
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• v.26 no.1
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• pp.103-108
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• 1986

The oil emulsion and alhydrogel pilli vaccines were prepared from a strain(O9: K35, K99, F41) of enterotoxigenic Escherichia coli isolated from calves with diarrhea and their immunogenicity was tested in guinea-pigs, pregnant goats and cows. Serum antibody responses to K99 and F41 antigens in guinea-pigs given experimental oil and gel vaccines peaked at 4 and 6 weeks after vaccinations. At that time, the mean hemagglutination inhibition titers to K99 and F41 antigens in guinea-pigs given oil vaccine were 1:25 and 1:1, 218 and those given gel vaccine were 1:54 and 1:724 respectively. Agglutinin titers in pregnant goats given the oil vaccine were significantly higher(mean 1:2,347) compared to those of control group(mean 1:160). Less than 12.5% of goatlings from vaccinated goats developed scours compared to nearly 100% in control group after oral challenge with enterotoxigenic Escherichia coil within 24 hours after birth. The highest agglutinin titers of cow serum and colostrum and of the serum of calves 48 hours after birth from cows given oil vaccine were 1:256, 1:512 and 1:64 respectively. On the other hand, those titers of serum and colostrum and of the serum of nursing calves from nonvaccinated cows were 1:8, 1:16 and 1:20 respectively. The protective efficacy of the oil emulsion vaccine was 72.1% under field conditions. These results strongly indicated that the vaccine could be applied for protection of diarrhea caused by enterotoxigenic Escherichia coli in calves.