• Food Science and Biotechnology
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• v.17 no.4
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• pp.878-882
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• 2008

The efficacy of citric acid-aqueous chlorine dioxide ($ClO_2$) treatment of radish seeds artificially contaminated with Escherichia coli was studied. Radish seeds were inoculated with E. coli. Following inoculation, samples were stored at $4^{\circ}C$ and soaked in citric acid or aqueous $ClO_2$ for 10 min. The treatment of radish seeds using 200 ppm aqueous $ClO_2$ solution caused a 1.5 log CFU/g reduction in the population of E. coli. Compared to the aqueous $ClO_2$ treatment, soaking radish seeds in 2.0% citric acid solution for 10 min was more effective in reducing E. coli populations on radish seeds. The efficacy of spray application of chlorine (100 ppm) or 0.5% citric acid to eliminate E. coli during the germination and growth of radish was investigated. Radish seed inoculated with E. coli was treated for the duration of the growth period. Although it resulted in a decrease in the E. coli population, the spray application of 100 ppm chlorine during the growth period was not significantly effective. In contrast, the combined treatment of seeds using 200 ppm aqueous $ClO_2$ and treatment of sprouts with 0.5% citric acid solution during sprout growth was hardly effective in eliminating E. coli.

• Journal of Dairy Science and Biotechnology
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• v.39 no.2
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• pp.51-62
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• 2021

Escherichia coli are the predominant facultative bacteria found in the gastrointestinal tract of animals and humans. Some strains of E. coli that acquire virulence factors and cause foodborne and waterborne diseases in humans are called pathogenic E. coli and can be divided into five pathotypes according to the virulence mechanism: EAEC, EHEC, EIEC, EPEC, and ETEC. Although selective media have been developed to detect E. coli, distinguishing pathogenic strains from non-pathogenic ones is difficult because of their similar biochemical properties. Therefore, it is very important to find a new and effective diagnostic method to identify pathogenic E. coli. With recent advances in molecular biology and whole genome sequencing, the use of polymerase chain reaction (PCR) is increasing rapidly. In this review paper, we provide an overview of pathogenic E. coli and present a review on PCR detection methods that can be used to diagnose pathogenic E. coli. In addition, the possibility of real-time PCR incorporating IAC is introduced. Consequently, this review paper will contribute to solving the current challenges related to the detection of pathogenic E. coli.

• Microbiology and Biotechnology Letters
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• v.16 no.4
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• pp.316-319
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• 1988

Pectate Lyase (PL) was cloned from alkali-tolerant Bacillus sp. YA-14 into Escherichia coli MB1000 by inserting HindIII-generated DNA fragment into the HindIII site of pBR322 and then screening recombinant transformant for the ability to hydrolyze sodium polypectate on agar plate, The recombinant plasmid, called pYPC29, was isolated, and the size of the cloned HindIII fragment was found to be 1.6 kb. The PL gene was stablely maintained and expressed efficiently in Escherichia coli. The Pt accumulated largely in the periplasmic space of Escherichia coli clones.

• Bulletin of the Korean Chemical Society
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• v.30 no.8
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• pp.1891-1892
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• 2009

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.3
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• pp.571-575
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• 2004

Escherichia coli O157:H7 cause hemorrhagic colitis and the extraintestinal complication of hemolytic-uremic syndrome, with their higher incidence occurring in children. Lipopolysaccharide (LPS) of E. coli O157:H7 is very important to make IgG anti-LPS with bactericidal activity. To identify the characteristic of E. coli OI57:H7, we isolated 60 MDa plasmid and amplified stx genes of shiga-like toxin (Stx) 1, 2 of E. coli O157:H7 by polymerase chain reaction (PCR) method. Using the simple purification method which contained phenol extract, ethanol precipitation and gel filtration steps, the LPS of E. coli O157:H7 was isolated and purified. Finally, we confirmed the purity of LPS through SDS-PAGE and silver nitrate staining.

• Pediatric Infection and Vaccine
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• v.22 no.3
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• pp.194-200
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• 2015

Purpose: Urinary tract infection (UTI) is a common bacterial infection in children and Escherichia coli is a predominant pathogen. The purpose of this study is to evaluate phylogenetic groups and virulence factors of E. coli causing UTI in children in Korea. Methods: From October 2010 to April 2013, urinary E. coli strains were isolated from the 33 pediatric patients of UTI. Multiplex polymerase chain reactions were performed to evaluate the phylogenetic groups and 5 virulence factor genes (fimH, sfa, papA, hylA, and cnf1) of E. coli. Distribution of molecular characteristics of E. coli was analyzed by clinical diagnosis and accompanying vesicoureteral reflux (VUR). Results: Most (84.8%) uropathogenic E. coli were belonged to phylogenetics group B2 and the others (15.2%) were belonged to group D. The virulence factors were distributed as: fimH (100%), sfa (100%), hylA (63.6%), cnfI (63.6%), and papA (36.4%). According to clinical diagnosis, phylogenetic distribution of E. coli strain was 92.3% of B2 and 7.7% of D in acute pyelonephritis and 57.1% of B2 and 42.9% of D in cystitis. Distribution of virulence factors was similar in both groups. In patients with acute pyelonephritis, phylogenetic distribution was similar in VUR and non-VUR group, but proportion of papA genes were lower in VUR group than that of non-VUR group (43.8% vs. 20.0%, P=0.399). Conclusions: This study provides current epidemiologic molecular data of E. coli causing pediatric UTI in Korea and will be a fundamental for understanding the pathogenesis of pediatric UTI.

• Journal of Food Hygiene and Safety
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• v.16 no.2
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• pp.89-95
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• 2001

This study was conducted to find material having antibacterial activity. The effects of preservatives, antibiotics and oriental medicines on growth of teated microorganisms were investigated. The growth of all tested bacteria was inhibited by water extract of Schizandra chinensis. Antibacterial activity on the concentration of Schizandra chinensis extract was tested. The growth of Escherichia coli W3110, Enterobacter colacae MG82 and Salmonella typhimurium was extraordinarily inhibited by more than 0.2% concentration of Schizandra chinensis extract. The specific growth rate of Escherichia coli W3110, Enterobacter cloacae ME82 and Salmonella typhimurium under control conditin had mean values of 0.514(hr￣), 0.381(hr￣) and 0.489(hr￣), respectively. When 0.2% of Schizandra chinensis extract was added, specific growth rates of Escherichia coli W3110, Enterobacter colacae MG82 and Salmonella typhimurium wre decreased, compared to contorl, in 1.26, 2.23 and 1.50 fold, respectivley. Minimal inhibiotory concentration of Schizandra chinensis extract was 0.25% on the tested microorganisms The growth of Enterobacter cloacae MG82 was more inhibited by Schizandra chinensis extract than other tested microorganisms.

• 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 Veterinary Research
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• v.26 no.1
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• pp.97-102
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• 1986

The prevalence of diarrhea caused by enterotoxigenic Escherichia coli was surveyed on 445 calves in 6 farms which were located in the central part of Korea. The incidence of enterotoxigenic Escherichia coli in calves with diarrhea was investigated by detecting the K99 and F41 antigens from the isolated strains of Escherichia coli The incidence of colibacillosis in calves was 23.3%. Of 238 strains of Escherichia coli isolated from calves with diarrhea, 73 strains(30.6%) were proved possessing the K99 antigen by mannose-resistant hemagglutination(MRHA) using horse red blood cells and 79(33.1%) possessing F41 antigens by MRHA using guinea-pig red blood cells. The minca medium, nutrient broth, tryptic soy broth and brain heart infusion were tested for yield of K99 and F41 pili. The production of pili was greatest in minea medium. The best detachment method of the K99 and F41 pili from the cells was heat treatment for 20 minutes at $60^{\circ}C$ and concentration by precipitation with ammonium sulfate. The purified antigens of K99 and F41 were polypeptides with molecular weights of 18,500 and 29,500, respectively by sodium dodecyl sulfate-polyacrylamide gel electrophoresis.

• Korean Journal of Microbiology
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• v.39 no.2
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• pp.83-88
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• 2003

We cloned a gene encoding acetyl xylan esterase(axeA) of Streptomyces coelicolor A3(2) and studied its expression pattern in Escherichia coli. The full sequence of axeA was amplified by PCR. Sequence analysis of the PCR product revealed an open reading frame of 1,008 nucleotides encoding a protein consisted of 335 amino acid residues, with a calculated molecular mass of about 38 kDa. The base sequence showed 98% homology to the same gene of Streptomyces lividans. Two different kinds of acetyl xylan esterases were produced in Escherichia coli(pLacI) by IPTG induction; their molecular weights were 38 kDa and 34 kDa, respectively. Of these, 38 kDa protein seemed to be a total protein holding N-terminal signal peptide region, whereas 34 kDa protein seemed to be a matured protein without signal peptide which was produced by peptide bond cleavage between two amino acid residues of alanine 41 and alanine 42.