• Fisheries and Aquatic Sciences
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• v.5 no.2
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• pp.79-86
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• 2002

Listeria spp. were isolated from the samples submitted from various seafood plants such as raw materials, products, swab samples of plants floor and conveyor belts through the whole processing procedures. All the samples were collected from 3 kinds of seafood plants such as a imitation crab meat plant, jeotgal plant and frozen seafood plant. And also serotypes of the identified L. monocytogenes were determined. Among the 301 strains of isolated Llsteria spp., 96 strains, 179 strains and 26 strains were identified as L. monocytogenes, L. innocua and L. welshimeri, respectively. While among the 145 strains of Listeria spp. isolated from the imitation crab meat plant, $74\;(51.0\%)$ strains, $64\;(44.1\%)$ strains and $7\;(4.8\%)$ strains were identified as L. monocytogenes, L. innocua and L. welshimeri, respectively. In the case of the 126 strains of Listeria spp. isolated from the frozen seafood plant, $22\;(17.5\%)$ strains of L. monocytogenes,$93\;(73.8\%)$ strains of L. innocua, and $11\;(8.5\%)$ strains of L. wdshimeri were detected. Among the 30 strains isolated from a jeotgal plant, $22\;(73.3\%)$ strains of L. innocua and $8\;(26.7\%)$ strains of L. welshimeri were detected. The detection rates of L. monocytogenes, one of the very important food poisoning bacteria especially in frozen and/or refrigerated seafoods, were relatively high as $77.1\%$ (74/96 strains) in a imitation crab meat plant and $22.9\%$ (22/96 strains) in a frozen seafood plant, but not detected from jeotgal plant. Distribution of L. monocytogenes serotypes and characterization were examined. The serotypes of 96 L. monocytogenes isolated from pork skin, pork fat, the floor and conveyor belts were 1/2a $(59.4\%)$, l/2b $(6.2\%)$, 1/2c $(12.5\%)$ and unknown serotypes $(21.9\%)$. Unknown serotypes were divided into three specific groups by the O antigen they have.

• 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.

• Journal of Food Hygiene and Safety
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• v.23 no.3
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• pp.248-256
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• 2008

To investigate the epidemiological characteristics of 68 Listeria monocytogenes isolates, including 11 reference strains and 57 isolates from imported US beef, domestic meats(beef, pork, chicken meat), raw milk, and milk plants. L. monocytogenes was to evaluate the production of virulence proteins, such as hemolysin(LLO) and lecithinase(LCP), the adsorption of Congo red(CRA), and to detect virulence genes using the polymerase chain reaction(PCR). In the study of virulence protein production, 68(100%), 62(91.2%), and 54(79.4%) of the 68 L. monocytogenes strains were positive for LLO production, the LCP test, and the CRA test, respectively, while strains of other species, such as L. innocua, L. gray, L. murrayi, and L. welshimeri, were not. There were no significant differences between L. monocytogenes serotypes and the ability to produce LLO or LCP. L. monocytogenesstrains had very high hemolytic titers(2 to 16 fold), while the other Listeria species, other than L. ivanovii and L. seeligeri, did not. The hemolysin activities of L. monocytogenes, L. ivanovii, and L. seeligeri usually exceeded 1.0 HU/mg, while those of other Listeria spp. were less than 0.04 HU/mg. In the PCR assay, all of the L. monocytogenes strains contained the hlyA, plcA, plcB, inlA, and inlB virulence genes and produced a product of the expected size. In the PCR of the actA gene, the expected 385-bp product was seen in 39(57.4%) L. monocytogenesstrains, while an unexpected 268-bp product was seen in 29(42.6%) strains. Most L. monocytogenes strains isolated from Hanwoo beef produced the 385-bp actA gene product, while strains of imported US beef usually produced the 268-bp actA gene product. By contrast, no virulence gene products were amplified in the other Listeria spp.

• The Korean Journal of Food And Nutrition
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• v.17 no.3
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• pp.254-259
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• 2004

Rapid detection of foodbome pathogens is becoming increasingly important. The requirement for faster, more reliable tests has lead to the development of a wide range of rapid methods. Among these methods, the use of systems based on nucleic acid based detection has been increasing since they offer advantages of reduction in test time and more reliable detection or identification. Random Amplification Polymorphic DNA(RAPD) method has been used to fingerprint foodbome microorganisms; Listeria monocytogenes. In this study, 10-mer primer OPG-13(5'-CTCTCCGCCA-3') was used to generate RAPD-PCR for detection of pathogenic L. monocytogenes of Listeria spp. Among 20 primers tested, OPG-13 showed on acceptable result for the differentiation of a pathogenic Listeria from non-pathogenic microorganisms. Pathogenic Listeria, L. monocytogenes(ATCC 15313, 19111, 19112, 19113) showed two bands for 700 bp and 1,500 bp while non-pathogenic bacteria, L. ivanovii, L. grayi, L. murrayi, L. innocua, L. welshimeri, and L. seeligeri had only one band sizing from 2,000 to 2,300 bp. This RAPD method proved to be a valuable to gain important information on sources of pathogenic bacteria in food industry.

• Korean Journal of Veterinary Research
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• v.31 no.3
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• pp.279-284
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• 1991

To investigate the epidemiological aspects of listeriosis, serotypes of L monocytogenes and antimicrobial susceptibilities of Listeria spp isolated from chicken carcases and chicken slaughter house environmental specimens were determined. Of 28 L monocytogenes strains, 12 strains(42.9%) were serotype 4, and the remaining 16 strains were untypable. Peak distributions of minimum inhibitory concentration$({\mu}g/ml)$ of the isolates were $0.78{\mu}g/ml$ for ampicillin, $0.39{\mu}g/ml$ for erythromycin and penicillin G, $1.56{\mu}g/ml$ for tetracycline and $6.25{\mu}g/ml$ or $12.5{\mu}g/ml$ for chloramphenicol, and $3.13{\mu}g/ml$ to > $100{\mu}g/ml$ for kanamycin and neomycin. Most of 214 isolates were sensitive to ampicillin and erythromycin, but 20. 1~78. 0% of the strains were resistant to tetracycline, kanamycin, penicillin-G and neomycin. Single or double drug resistance were observed in 75.8% of the resistant strains. The most common resistance patterns were Nm P-G(37.4%) in double pattern and P-G(23.7%) in single pattern.

• Korean Journal of Veterinary Service
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• v.25 no.1
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• pp.31-37
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• 2002

Major hazards existed in slaughterhouse are pathogenic microorganisms originated from intestinal microflora of slaughtered animals. This study was intended for the identification of microbial contamination sources during pork slaughtering in small plants. Total aerobic bacteria, Coliform group, Salmonella spp, Listeria monocytogenes, and Campylobacter jejuni/coli were isolated from the surface sample of pork carcasses. Contamination level among different sampling points of ham, belly and neck did not showed statistical differences. Therefore, the mixed sampling from belly and neck of carcass could be effective for microbiological monitoring. Isolation rates of pathogenic microorganisms showed Salmonella spp 20.9%, Listeria monocytogenes 10.5%, and Campylobacter jejuni/coli 8.1% from 296 sampling points. High prevalence rate of Salmonella spp indicated that the contamination of intestinal microflora occurred due to unsanitary processing control, which required HACCP system in small plants. It was recommended that the prerequisite program should be a key factor for a successful HACCP system implementation especially in small size slaughterhouse.

• Journal of Food Hygiene and Safety
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• v.30 no.1
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• pp.103-108
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• 2015

Weissella spp. from traditional Korean foods of Kimchi were isolated and characterized against food-borne pathogenic Listeria monocytogens. The isolates were identified as W. cibaria 0D17 and W. confusa 0D23 from Kimchi by the biochemical characteristics and 16S DNA sequencing. The culture solutions of the isolates adjusted to pH 7.0 showed L. monocytogens inhibition. To analyze the quantitative detection of L. monocytogenes, real-time PCR was performed according to the SYBR Green I method. The isolates grew well and L. monocytogens did not grow during the co-culture with those strains at $37^{\circ}C$. Therefore, W. cibaria 0D17 and W. confusa 0D23 might be the candidates as the functional lactic acid bacteria for improving food safety.

• Fisheries and Aquatic Sciences
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• v.5 no.1
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• pp.54-58
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• 2002

The polymerase chain reaction (PCR) amplification technique was used for comparison of Listeria monocytogenes serotypes. PCR primers for the fragment of invasion-associated protein (iap) gene were highly specific for all the serotypes of L. monocytogenes. Other Listeria spp., such as Listeria ivanovii and Listeria innocua were not produced the PCR fragments by above primer set. The nucleotide sequences of PCR products showed high homologies in comparison of all the isolated serotypes except unknown type II-2. The deduced amino acid sequences of the PCR products also showed similar to one another. The various region of the PCR products, called a Thr-Asn repeat region was presented. All of isolated L. monocytogenes serotypes possessed 16 to 20 Thr-Asn repeats.

• Food Science and Preservation
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• v.30 no.2
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• pp.262-271
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• 2023

The objective of this study is to compare and assess the effectiveness of real-time polymerase chain reaction (RT-PCR), loop-mediated isothermal amplification (LAMP), and the selective agar plate method for the detection of Salmonella spp. and Listeria monocytogenes in ready-to-eat (RTE) foods. In RTE foods, the detection performance of the three methods (RT-PCR [SureTect^TM kit and PowerChek^TM kit], LAMP [3M MDS], selective agar) were similar at 0-10, 10-50, 50-100, and 100- CFU/mL of Salmonella spp. and L. monocytogenes. We found that with RT-PCR, the Ct value of salad was significantly higher (p<0.05) than other RTE foods, indicating that fiber plays a critical role as an obstacle to the rapid detection of Salmonella spp. However, the Ct value displayed a mixed pattern according to the inoculation level of L. monocytogenes. The use of rapid detection kits and machines mostly depends on the user's choice, with accuracy, ease of use, and economy being the primary considerations. As an RT-PCR kit, SureTect^TM and PowerChek^TM showed high accuracy in detecting Salmonella spp. and L. monocytogenes in RTE foods, showing that they can replace the existing RT-PCR kits available. Additionally, LAMP also showed excellent detection performance, suggesting that it has the potential to be used as a food safety management tool.

• Korean Journal of Veterinary Research
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• v.45 no.3
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• pp.359-367
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• 2005

This study was carried out to understand the contamination patterns of Listeria in pork processing plants. A total of 402 samples were collected from carcass, pork during processing, surfaces of equipment and environment, and 238 isolates of Listeria species were identified. L. innocua was found in 64.7% of the isolates, L. monocytogenes in 33.2%, and L. welshimeri in 2.1%. Random amplified polymorphic DNA (RAPD) analysis performed to investigate the origin and routes of Listeria contamination, showed 21 composite types of L. monocytogenes and 26 composite types of L. innocua. It was confirmed that Listeria contamination begins with contaminated incoming carcass and ever-present contaminants in the processing environments. The persistence and dissemination of the same strain of L. monocytogenes and L. innocua throughout the processing line revealed that the sanitation standard operating procedure should be implemented to minimize the risk of colonization in the workplace. Molecular subtyping of L. innocua allowed us to tracing the possibility of cross-contamination during processing.