• Korean Journal of Veterinary Service
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• v.28 no.1
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• pp.71-79
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• 2005

In this study, a total of 2,119 samples was taken from bovine feces and carcass from March 2002 to December 2003. And those were examined for the presence of enterohemorrhagic E coli O157:H7. The properties of the isolates were characterized for biochemical features, serotypes, virulence genes and antimicrobial susceptibility. Forty five strains($3.7\%$) of E coli O157:H7 were isolated from 1,208 fecal samples and were not detected in carcass using immunomagnetic separation technique and selective media. In multiplex PCR using stx1, stx2, eaeA and hlyA primers, the amplified bands at 180 bp, 255bp, 384bp and 534bp were observed, respectively. In antimicrobial susceptibility test, all isolates were susceptible to amoxicillin/clavulanic acid and cefazolin. The isolates were most resistant to sulfisoxazole($24.4\%$), followed by streptomycin($22.2\%$), tetracycline($20.0\%$). Eight strains($17.8\%$) of 45 isolates showed the multi-resistant patterns with over 3 drugs.

• Journal of Microbiology
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• v.44 no.1
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• pp.92-97
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• 2006

We developed an mPCR assay for the simultaneous detection, in one tube, of Escherichia coli O157:H7, Salmonella spp., Staphylococcus aureus and Listeria monocytogenes using species-specific primers. The mPCR employed the E. coli O157:H7 specific primer Stx2A, Salmonella spp. specific primer Its, S. aureus specific primer Cap8A-B and L. monocytogenes specific primer Hly. Amplification with these primers produced products of 553, 312, 405 and 210 bp, respectively. All PCR products were easily detected by agarose gel electrophoresis, and the sequences of the specific amplicons assessed. Potential pathogenic bacteria, in laboratory-prepared and four commercially available kimchi products, were using this mPCR assay, and the amplicons cloned and sequenced. The results correlated exactly with sequences derived for amplicons obtained during preliminry tests with known organisms. The sensitivity of the assay was determined for the purified pathogen DNAs from four strains. The mPCR detected pathogen DNA at concentrations ranging from approximately 0.45 to $0.05\;pM/{\mu}l$. Thus, this mPCR assay may allow for the rapid, reliable and cost-effective identification of four potentially pathogens present in the mixed bacterial communities of commercially available kimchi.

• Food Science and Preservation
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• v.7 no.1
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• pp.124-131
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• 2000

Antibacterial activities of powdered spices(garlic , ginger, cinnamon and clove) against pathogenic Escherichia coli )157:H7 and Staphyloccus auresus were investigated. Spice powder was added in was exponetial phase of each bacterial culture . Growth inhibition was determined by the absorbance at 660nm and morphological changes of the cells were observed by transmission electron microscope (TEM). Ginger powder has the highest antibacterial activity, following cinnamon , clove and garlic has the least activity.Growth of Escherichia coli O157:H7 and Staphyloccus aureus were completely inhibited within 5 hours after addition of 1 % of garlic , 0.3% of ginger or cinnamon , 0.5% of clove powder on the exponential phase of the cells. Spice untreated cells of E. coli and S. aureus, the cytoplasm was entirely surrounded by rigid cell wall and cell walls formed a smooth layer well attached to the plasma membrane. In the cells of E. coli and S. aureus treated with spice powder, cell wall and plasma membrane were lysed and severely damaged. E.coli cells growth in the presence of spice powder showed plammolysis, the loss of electron dense material, the formation of extra cellular blebs and cytoplasm burst out from the cell. S .sureus cells grown in the presence of spice powder showed swell of cell wall, the loss of electron dense material , coagulation of cell cytoplasm and formation of extra cellular blebs. Severely damaged cells of S. aureus lost whole cytoplasm and left as ghost of the cell. Spice powder stimulated autolyssi and induced cell death.

• Journal of Dairy Science and Biotechnology
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• v.40 no.4
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• pp.151-162
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• 2022

Although many developed countries (USA, Canada, and several EU countries) allow raw milk cheese to be aged more than 60 days, these countries have strict standards for the aging conditions, such as temperature, of raw milk cheese. Spiking experiments were conducted with Camembert cheese made from raw milk, to assess the microbiological safety of raw milk cheese aged for more than 60 days. We spiked Escherichia coli O157:H7 into raw milk with different inoculation levels (high, medium, and low). Camembert cheese was prepared from the inoculated raw milk, then aged in an incubator for up to 9 weeks (63 days). There were no significant differences in pH and water activity (aW) between uninoculated cheese and cheese samples inoculated with E. coli O157:H7 (p<0.05). The pH and aWof the Camembert cheese decreased throughout the storage period. In conclusion, E. coli O157:H7 did not affect the pH and aW of the cheese samples. Cell counts were conducted every week using the agar-plating method. Inoculated cells were completely eliminated, especially in Camembert cheese, after 60 days, and the reduction rate of cells was much faster in Camembert cheese.

• Preventive Nutrition and Food Science
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• v.5 no.3
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• pp.131-135
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• 2000

The inhibitory effect of various organic acids on the growth and survival of Escherichia coli O157:H7 in tryptic soy broth with 0.6% yeast extract at 37$^{\circ}C$ or 4$^{\circ}C$ was determined. Minimal inhibitory pHs of acetic acid, citric acid, fumaric acid, hydrochloric acid and lactic acid were 5.0, 4.0, 4.5, 4.0 and 4.5, respectively. Acetic acid (0.012 m) showed the strongest antimicrobial activity, based on the pH values or equivalent molar concentrations, followed by lactic acid (0.0006 M), fumaric acid (0.004M) and citirc acid (0.004 M), respectively, E. coli O157:H7 with an initial inoculum of {TEX}$10^{7}${/TEX} CFU/ml and {TEX}$10^{5}{/TEX} CFU/ml in tryptic soy broth supplemented with 0.6% yeast extract, acidified to target pH with citric, fumaric and lactic acids at 37$^{\circ}C$, was completely inactivated after 7 d and 5 d incubation, respectively, except for the acetic acid (9 d). The bactericidal effect decreased at the same pH when the incubation temperature a was reduced from 37$^{\circ}C$ to 4$^{\circ}C$. The pH values of 0.2% acetic (pH 5.1), 0.6% citric (pH 4.2) and 0.4% lactic acid (pH 4.3) in TSBYE were almost correspondent to the minimal inhibitory pH values on E. coli O157:H7 of acetic (pH 4.0), citric (pH 4.0) and lactic acids (pH 4.5).

• Korean journal of food and cookery science
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• v.27 no.4
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• pp.17-26
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• 2011

This study was performed to analyze the antibacterial activity against food hazardous microorganisms and antimutagenic effects of Sanguisorba officinalis L. ethanol extracts on Salmonella Typhimurium TA100. The antibacterial activity was evaluated by paper disc diffusion assay, minimum inhibition concentration (MIC), and optical density of the culture with the ethanol extract for 24 hr. Antibacterial activity was tested with seven microorganisms including Escherichia coli, Escherichia coli O157:H7, Pseudomonas aeruginosa, Salmonella Typhimurium, Listeria monocytogenes, Bacillus cereus, and Staphylococcus aureus. The paper disc diffusion assay showed distinct clear inhibition zones around the discs treated with the extract for five microorganisms, except Escherichia coli and Escherichia coli O157:H7. MIC values were 0.625-2.5 mg/mL for these five strains that showed clear zones. The time-kill assay was consistent with the results from the paper disc diffusion assay and MIC test. Additionally, antimutagenicity of the extract was determined using the Ames test. The ethanol extract at 5 mg/plate inhibited 72.42% and 89.85% of mutagenicity induced by 4-nitroquinoline 1-oxide and sodium azide, respectively. These results demonstrate that the ethanol extract from S. officinalis L. has remarkable antibacterial activity and antimutagenicity.

• Korean Journal of Food Science and Technology
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• v.47 no.5
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• pp.593-598
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• 2015

This study determined the thermal resistance of Bacillus cereus, Escherichia coli O157:H7, and Listeria monocytogenes in multi-grain soymilk and proposes processing conditions that meet the national standard for retort food products in Korea. D and z values were calculated from thermal inactivation kinetic curves after heating at 55, 60, and $65^{\circ}C$. The D value for B. cereus at $55^{\circ}C$ was the highest (22.8 min), followed by that for E. coli O157:H7 (18.8 min) and L. monocytogenes (17.6 min). At $60-65^{\circ}C$, the order was L. monocytogenes ($D_{60-65^{\circ}C}=3.4-0.9min$), E. coli O157:H7 (3.0-0.3 min), and B. cereus (1.2-0.3 min). The z values for these species were 5.2, 5.5, and $7.7^{\circ}C$, respectively. The Korean national standard for retort food products was achieved by thermal processing at $124{\pm}2^{\circ}C$ for 0.3-2.2 min. This study provides useful data for ensuring both the microbiological safety and product quality of multi-grain soymilk products.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.10
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• pp.1265-1269
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• 2017

This study was performed to evaluate the effects of combined treatment of clove bud essential oil (CBEO) and mild heat (MH) on inactivation of Escherichia coli O157:H7 inoculated onto red oak leaves. Combined treatment of 0.2% CBEO with MH at $50^{\circ}C$ exhibited the highest inhibitory effect against E. coli O157:H7 among treatments, resulting in 1.45 log reduction compared with water washing treatment. In addition, inhibitory effect of the combined treatment was maintained during storage of red oak leaves at $4^{\circ}C$ for 9 days, showing 1.67~2.25 log reductions compared with non-treated samples. Thus, these results indicate that combined treatment with CBEO/MH can be used to ensure the microbiological safety of fresh leaf vegetables such as red oak leaves during storage.

• Food Science and Preservation
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• v.6 no.2
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• pp.239-244
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• 1999

Antimicrobial activity to the extracts of Perilla frutescens Briton var. acuta Kudo was investigated against various foodborne pathogenes or food poisioning microorganisms(Aspergillus flavus KCTC 6143 and KCTC 6961, Aspergillus niger ATCC 4695, Listeria monocytogenes ATCC 15313, Staphylococcus aureus 196E ATCC 13565, Escherichia coli O157:H7 ATCC 43895, Salmonella typhimurium ATCC 13311 and Yersinia enterocolitica). The ethanol extract of Perilla frutescens Briton var. acuta Kudo was very stable over heat at $121^{\circ}C$ for 15 min. In concentration of $1000\mu\textrm{g}$/mL into culture broth(TSB), the ethanol extract of Perilla frutescens Briton var. acuta Kudo showed the strongest antimicrobial activities against Listeria monocytogenes, followed by Staphylococcus aureus 196E, Salmonella typhimurium. Gram negative bacteria(Escherichia coli O157:H7, Salmonella 쇼phimurium, Yersinia enterocolitica) were less sensitive than Cram positive bacteria but the growth of Escherichia coli O157:H7 and Yersinia exterocolitica were inhibited with increasing concentrations of the extract in culture broth.

• Journal of Food Hygiene and Safety
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• v.28 no.1
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• pp.36-40
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• 2013

This study was performed to determine the ranking foods and related foodborne pathogens for the impact of climate change, e.g., increasing temperature, on microbiological food safety. To do this, we developed an impact-ranking model comprising an Excel spreadsheet by using Risk Ranger. Because of a lack of data, input values in this model were determined on the basis of an expert's opinion. These values also were converted to normal distribution, and the developed model was simulated using @RISK. In conclusion, the 5 superior ranking foods and related foodborne pathogens for climate change impact were as follows: ready-to-eat foods (RTE) (Staphylococcus aureus, Salmonella spp., and Escherichia coli O157:H7); bread and rice cakes (S. aureus and Bacillus cereus); meat and egg products (Salmonella spp., E. coli O157:H7, and S. aureus); tofu (bean curds) and jellies (B. cereus, E. coli O157:H7, and S. aureus); and fish products (S. aureus, Vibrio spp., and E. coli O157:H7).