• KSBB Journal
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• v.13 no.2
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• pp.168-173
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• 1998

Gamma irradiated and non-irradiated Agrimonia pilosa Ledebour were extracted by 70% ethanol. The combined effects of the Agrimonia pilosa Ledebour extract and NaCl on survival of Escherichia coli O157:H7 in tryptic soy broth were investigated. E. coli O157:H7 decreased ca 1 log cycle by the addition of 2% sample extract, and the anthbacterial activity was increased as the concentration of sample extract was increased. The irradiation effect of the sample on antibacterial activity was not observed. On the treatment of NaCl alone, E. coli O157:H7 was inactivated (ca 3~4 log cycle reduction within 48 hr) in more than 7% NaCl. The higher inactivation(ca 5 log cycle reduction within 48 hr) occurred in the presence of 2% sample extract and 5% NaCl than in the addition of each alone. The extracted antibacterial substance was stable in the pH range of 4.0 to 7.0, heat treatment at 121$^\circ C$ for 15 min, and freezing at -18$^\circ C$ and thawing at 37$^\circ C$. There fore, the sample extract, would substantially increase the food-safety in terms of E. coli O157:H7.

• Journal of Microbiology and Biotechnology
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• v.26 no.12
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• pp.2060-2065
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• 2016

Characteristics of E. coli O157:H7-specific infection bacteriophages (O157 coliphages) and broad-host-range bacteriophages for other E. coli serotypes (broad-host coliphages) were compared. The burst sizes of the two groups ranged from 40 to 176 PFU/infected cell. Distributions of the virulence factors stx1, stx2, ehxA, and saa between the two groups were not differentiated. Broad-host-range coliphages showed lower stability at $70^{\circ}C$, in relation to O157 coliphages. However, O157 coliphages showed high acid and ethanol tolerance by reduction of only 22% and 11% phages, respectively, under pH 3 and 70% ethanol for 1 h exposure. Therefore, these results revealed that the O157 coliphages might be more stable under harsh environments, which might explain their effective infection of the acid-tolerant E. coli O157:H7.

• Korean Journal of Food Science and Technology
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• v.50 no.4
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• pp.414-419
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• 2018

Escherichia coli O157:H7 is one of the most common foodborne pathogens responsible for outbreaks of hemorrhagic colitis, which can lead to the life-threatening hemolytic-uremic syndrome. In this study, we identified phytochemicals that specifically inhibit the expression of LEE operon in E. coli O157:H7. Among phytochemicals, diosmin decreased the adherence of E. coli O157:H7 towards Caco-2 cells in vitro (p<0.01) and its biofilm formation activity (p<0.05). Quantitative RT-PCR analysis revealed that the transcripts of Ler-regulated genes and genes related to curli production were significantly reduced in the presence of diosmin. However, diosmin does not affect bacterial viability, indicating that the resistance rate to diosmin was remarkably low. Overall, these results provide significant insights into the development of a novel anti-infective agent that is different from conventional antibiotics.

• Korean Journal of Soil Science and Fertilizer
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• v.47 no.6
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• pp.432-436
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• 2014

While searching for healthier diets, people became more attentive to agricultural organic products. However, organic foods may be more susceptible to microbiological contamination because of the use of livestock manure compost and liquid manure, potential sources of pathogenic bacteria. This study was undertaken to investigate the persistence of Salmonella enterica, Escherichia coli O157:H7, and Listeria monocytogenes in soil, liquid manure amended soil, and liquid manure. Loamy soil, liquid manure amended soil, and liquid manure were inoculated with S. enterica, E. coli O157:H7, and L. monocytogenes. Samples were incubated in consistent moisture content at $25^{\circ}C$. Samples had been periodically collected during 120 days depending on the given conditions. S. enterica and E. coli O157:H7 survived over 120 days in loamy soil and over 60 days in liquid manure amended soil, respectively. L. monocytogenes decreased faster than other pathogens in soil. S. enterica, E. coli O157:H7, and L. monocytogenes survived for up to 5 days in liquid manure. S. enterica and E. coli O157:H7 in soil decreased by 2 to $2.5log\;CFU\;g^{-1}$ for 120 days. S. enterica and E. coli O157:H7 in liquid manure amended soil decreased slowly for 21 days. However, S. enterica, E. coli O157:H7, and L. monocytogenes sharply decreased after 21 days. S. enterica, E. coli O157:H7, and L. monocytogenes in soil increased by 0.5 to $1.0log\;CFU\;g^{-1}$ for 7 days. Foodborne pathogens in soil and liquid manure amended soil gradually decreased over time.

• Journal of Biosystems Engineering
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• v.38 no.4
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• pp.335-340
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• 2013

Purpose: This study was performed to develop a lateral flow strip sensor for the detection of pathogenic Escherichia coli O157:H7 in various samples. Also, feasibility of using an image analysis method to improve the interpretation of the strip sensor was evaluated. Methods: The lateral flow strip sensor has been fabricated based on nitrocellulose lateral-flow membrane. Colloidal gold and E. coli O157:H7 antibodies were used as a tag and a receptor, respectively. Manually spotted E. coli O157:H7 antibody and anti-mouse antibody on nitrocellulose membrane were used as test and control dots, respectively. Feasibility of the lateral flow strip sensor to detect E. coli O157:H7 were evaluated with serially diluted E. coli O157:H7 cells in PBS or food samples. Test results of the lateral flow strip sensor were measured with an image analysis method. Results: The intensity of the test dot started to increase with higher concentration of the cells were introduced. The sensitivities of the sensor were both $10^4$ CFU/mL Escherichia coli O157:H7 spiked in PBS and in chicken meat extract, respectively. Conclusions: The lateral flow strip sensor and image analysis method could detect E. coli O157:H7 in 20 min, which is significantly quicker than conventional plate counting method.

• Journal of Microbiology and Biotechnology
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• v.12 no.5
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• pp.780-786
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• 2002

An immunosensor based on surface plasmon resonance (SPR) with a self-assembled protein G layer was developed for the detection of Escherichia coli O157:H7. A self-assembled protein C layer on a gold (Au) surface was fabricated by adsorbing the mixture of 11-mercaptoundecanoic acid (MUA) and hexanethiol at various molar ratios and by activating chemical binding between free amine (-$NH_2$) of protein G and 11-(MUA) using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDAC) in series. The formation of a self-assembled protein G layer on an Au substrate and the binding of the antibody and antigen in series were confirmed by SPR spectroscopy. The surface morphology analyses of the self-assembled protein G layer on the Au substrate, monoclonal antibody (Mab) against E. coli O157:H7 which was immobilized on protein G, and bound E. coli O157:H7 extracts on Immobilized Mab against E. coii O157:H7 were performed by atomic force microscopy (AFM). The detection limit of the SPR-based immunosensor for E. coli O157:H7 was found to be about $10^4$ cells/ml.

• Journal of Food Hygiene and Safety
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• v.12 no.1
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• pp.78-82
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• 1997

Surface swab samples from beef (188), pork (240) and chicken (95) carcasses were collected from slaughterhouse in Kangwon and Kyunggi areas from March through July 1996. The samples were examined on the level of E. coli biotype I relevant to fecal contamination due to unsanitary processing control and the existence of verocytotoxin-producing E. coli (VTEC). E. coli biotype I were confirmed from 38.8% of beef, 40.0% of pork, and 69.5% of chicken carcasses. Little variation was noted among three sampling points; rump, flank and neck of beef, ham, belly and jowls of pork. coli O157:H7 was only confirmed from 2 of 188 beef carcasses. E. coli biotype I. All the isolated E. coli O157 showed positive for vero cell cytotoxicity test. Isolation rate of E. coli O157 in summer was higher than in spring. In case of pork and chicken carcasses, E. coli O157 was isolated in summer only.

• Journal of Food Hygiene and Safety
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• v.25 no.1
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• pp.1-5
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• 2010

The present study was evaluated the antibacterial effect of the combination of Coptidis rhizoma, Lonicerae Flos, and Paeonia japonica (1:1:1) extracts (CLP1000). Also, the effectiveness of CLP1000, dioctahedral smectite (DHS), and the combination of CLP1000 and DHS (CLPS1000) against E. coli O157:H7 infection was studied using ICR female mice. During the incubation period, the dose of 10% and 20% CLP1000 were inhibited the growth of E. coli O157:H7 by 30% and 47%, respectively. For 7 days after single challenge with E. coli O157:H7, forty female ICR mice were divided into four experimental groups which were orally administered with saline, 10% CLP1000, 10% DHS, and 10% CLPS1000, respectively. On the 3rd day, the number of E. coli O157:H7 in mouse feces was significantly decreased by administration of CLP1000 (p < 0.05), DHS (p < 0.05) and CLPS1000 (p < 0.001). On the 7th day, CLP1000 (p < 0.05) and CLPS1000 p < 0.001) administration significantly decreased the number of E. coli O157:H7. According to the results of the present study, administration of CLPS1000 to mice can reduce the severity of E. coli O157:H7 infection. Also, it is suggested that CLPS100 represents a good candidate for the treatment of enteric infections in domestic animals.

• Biomedical Science Letters
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• v.4 no.1
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• pp.43-56
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• 1998

A multiplex PCR method was designed by employing primers specific for the eaeA gene, conserved sequences of Shiga-like toxins (SLT-I.II), and the 60-MDa plasmid of enterohemorrhagic E. coli (EHEC) O157:H7 strain. A set of six synthetic oligonucleotide primers derived from sequences of the SLT-I.II, eaeA, and 60-MDa plasmid genes of E. coli O157:H7 were used in a multiplex PCR amplification procedure to detect these genes in the same enteric pathogens. In two enterohemorrhagic E. coli O157:H7 (ATCC 35150, ATCC 43894) reference strains, PCR products of 317bps (eaeA), 228bps (SLT-I.II), and 167bps (60-MDa plasmid) were successfully amplified simultaneously in a single reaction. However, the specific PCR products were not amplified in control strains of other enteric bacteria. The sensitivity of the multiplex PCR assay for detection of the SLT-I.II, eaeA, and 60-MDa plasmid genes of E. coli O157:H7 was found to be 2.5$\times$10$^{6}$ of bacteria in diarrheal stool to amplify all three bands. The multiplex PCR technology will allow large-scale screening of many clinical specimens or contaminated foods, and will be a very useful method for the detection of a wide range of microorganisms present in the environment, including EHEC O157:H7 in various types of specimens. The multiplex PCR assay has the potential to be used as a specific and rapid method for clinical diagnosis of disease caused by EHEC O157:H7.

• Korean Journal of Food Science and Technology
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• v.29 no.4
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• pp.771-775
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• 1997

Treatment with electron beam irradiation was investigated for the elimination of Escherichia coli O157:H7 which has been linked to outbreaks of foodborne illness on undercooked and raw meat. Before treatment, the maximum populations were observed at 16 hr when E. coli O157:H7 was incubated in TSB at $37^{\circ}C$. Incubation at $4^{\circ}C$ did not influence survival and growth of the strain. The numbers of E. coli O157:H7 were present about $10^{7}\;CFU/mL$ in the log $(6\;hr\;at\;37^{\circ}C)$ and stationary phase $(16\;hr\;at\;37^{\circ}C)$ of cells, respectively. Freezing $(24\;hr\;at\;-18^{\circ})$ had a more marked lethal effect. The $D_{10}$ value at $-18^{\circ}C$ of E. coli O157:H7 contaminated in frozen beef was 0.45 kGy, and inactivation factor were $6.67{\sim}11.11$ at the radiation doses of $3{\sim}5\;kGy$. Therefore, electron beam irradiation was an effective method to eleminate of E. coli O157:H7.