• Food Science of Animal Resources
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• v.38 no.4
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• pp.727-736
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• 2018

In this study, an immuno-magnetic bead (IMB)-based assay was developed to simultaneously detect Escherichia coli, Staphylococcus aureus, and Salmonella spp. and was tested in four animal-derived foods: beef, ham, egg, and ricotta cheese. The IMB-based assay exhibited good specificity by binding to five E. coli serotypes [capture efficiency (CE) average (avg.) 90.4%], five S. aureus strains (CE avg. 91.4%), and five Salmonella serotypes (CE avg. 95.4%) but not binding to non-target bacteria (CE<10%). Furthermore, the assay detected all three pathogens with a detection limit of 10 CFU/g without the need for enrichment or additional platforms. Since the results demonstrated that the IMB-based assay can effectively separate and enrich target bacteria from a variety of animal-derived food matrixes, the assay exhibits good specificity for potential use in providing rapid, immunological, presumptive identification of pathogenic bacteria.

• Food Science and Biotechnology
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• v.16 no.3
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• pp.337-342
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• 2007

Conventional methods for pathogen detection and identification are labor-intensive and take days to complete. Biosensors have shown great potential for the rapid detection of foodborne pathogens. Fiber-optic biosensors have been used to rapidly detect pathogens because they can be very sensitive and are simple to operate. However, many fiber-optic biosensors rely on manual sensor handling and the sandwich assay, which require more effort and are less sensitive. To increase the simplicity of operation and detection sensitivity, a binding inhibition assay method for detecting Listeria monocytogenes in food samples was developed using an automated, fiber-optic-based immunosensor: RAPTOR (Research International, Monroe, WA, USA). For the assay, fiber-optic biosensors were developed by the immobilization of Listeria antibodies on polystyrene fiber waveguides through a biotin-avidin reaction. Developed fiber-optic biosensors were incorporated into the RAPTOR to evaluate the detection of L. monocytogenes in frankfurter samples. The binding inhibition method combined with RAPTOR was sensitive enough to detect L. monocytogenes ($5.4{\times}10^7\;CFU/mL$) in a frankfurter sample.

• Journal of Microbiology and Biotechnology
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• v.20 no.4
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• pp.757-762
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• 2010

Cronobacter is a major foodborne pathogen in powdered infant formula and can lead to serious developmental after-effect and death to infants. The contamination of Cronobacter may be a high risk for the powdered foods. To isolate and identify Cronobacter from the powdered foods such as powdered infant formula and Saengsik in Korea, a conventional culture method, rapid identification system, PCR, and 16S rDNA sequencing were performed. As the results of isolation, seven Cronobacter spp. were isolated from seven out of 102 powdered infant formulas and 41 Cronobacter were isolated from 41 out of 86 Saengsiks. Forty-eight Cronobacter isolates were identified to be C. sakazakii and C. dublenisis by 16S rDNA sequence analysis. Most of the isolates were C. sakazakii and 13% of the isolates were C. dublinesis. One fourth of the C. sakazakii isolates showed different biochemical characteristics of negative nitrate reduction and nonmotility activities compared with the other strains reported previously.

• Neonatal Medicine
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• v.16 no.1
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• pp.94-98
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• 2009

Listeria monocytogenes (L. monocytogenes) is a foodborne anaerobic gram-positive rod and the third most common pathogen for neonatal meningitis. Although the mortality and morbidity of L. monocytogenes infections are high, thus causing serious problems in Western populations, neonatal listeriosis is relatively rare in Eastern countries, including Korea. Possible routes for intrauterine infection or vertical transmission of L. monocytogenes include infected placentas and the reproductive tract. Intrauterine infections may cause chorioamnionitis, preterm labor, spontaneous abortion, stillbirth, or neonatal infection. A high index of suspicion and early empirical antibiotic treatment are critical to achieve a favorable prognosis for neonatal listeriosis. We managed a case of L. monocytogenes sepsis and pneumonia in a premature neonate born at 26 weeks of gestational age from an asymptomatic mother with culture-proven placental infection. The neonate was successively treated with ampicillin and gentamicin.

• Journal of Microbiology and Biotechnology
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• v.20 no.1
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• pp.5-14
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• 2010

Enterohemorrhagic Escherichia coli O157:H7 is a major foodborne pathogen causing severe disease in humans worldwide. Healthy cattle are a reservoir of E. coli O157:H7, and bovine food products and fresh produce contaminated with bovine waste are the most common sources for disease outbreaks in the United States. E. coli O157:H7 also survives well in the environment. The abilities to cause human disease, colonize the bovine gastrointestinal tract, and survive in the environment require that E. coli O157:H7 adapt to a wide variety of conditions. Three major virulence factors of E. coli O157:H7 have been identified including Shiga toxins, products of the pathogenicity island called the locus of enterocyte effacement, and products of the F-like plasmid pO157. Among these virulence factors, the role of pO157 is least understood. This review provides a board overview of E. coli O157:H7 with an emphasis on pO157.

• Journal of Microbiology and Biotechnology
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• v.17 no.7
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• pp.1059-1070
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• 2007

Prion diseases, often called transmissible spongiform encephalopathies (TSEs), are infectious diseases that accompany neurological dysfunctions in many mammalian hosts. Prion diseases include Creutzfeldt-Jakob disease (CJD) in humans, bovine spongiform encephalopathy (BSE, "mad cow disease") in cattle, scrapie in sheep, and chronic wasting disease (CWD) in deer and elks. The cause of these fatal diseases is a proteinaceous pathogen termed prion that lacks functional nucleic acids. As demonstrated in the BSE outbreak and its transmission to humans, the onset of disease is not limited to a certain species but can be transmissible from one host species to another. Such a striking nature of prions has generated huge concerns in public health and attracted serious attention in the scientific communities. To date, the potential transmission of prions to humans via foodborne infection and iatrogenic routes has not been alleviated. Rather, the possible transmission of human to human or cervids to human aggravates the terrifying situation across the globe. In this review, basic features about prion diseases including clinical and pathological characteristics, etiology, and transmission of diseases are described. Based on recently accumulated evidences, the molecular and biochemical aspects of prions, with an emphasis on the molecular interactions involved in prion conversion that is critical during prion replication and pathogenesis, are also addressed.

• Bulletin of Food Technology
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• v.18 no.2
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• pp.99-108
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• 2005

As an alternative to gaseous sanitizer which having penetrating and diffusing capacities, aerosolsanitizer’s effect on killing pathogens was investigated. To test the efficacy of aerosolized sanitizer, peroxyacetic acid was aerosolized($5.42-11.42\mum$) by nebulizer(Royal-G Enterprise, ShenZhen,China) in a model cabinet against artificially inoculated target microorganisms on lettuce. Lettuceleaves were inoculated with a cocktail of three strains each of Escherichia coli O157:H7, Listeriamonocytogenes, and Salmonella Typhimurium and treated with sanitizer aerosol for 10 min, 30 and60 min in a model aerosol cabinet at room temperature($22\pm2^\circC$). After treatment, surviving cellsincluding injured cells were enumerated on appropriate selective agar or using the over-lay agar method, respectively. Inoculated lettuce leaves exposed to antimicrobial aerosol for 10 min experienceda 0.8 log reduction in E. coli O157:H7, a 0.3 log reduction in Salmonella Typhimurium and a 2.5 logreduction in L. monocytogenes when compared to the control. After 30 min treatment, the threepathogens were reduced in number of CFU by 2.2, 3.3, and 2.7-log and after 60 min, the reductions were 3.4, 4.5, and 3.8-log, respectively. Aerosolization can be new antimicrobial agents deliverysystem in food sanitizing.

• Proceedings of the Microbiological Society of Korea Conference
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• 2008.05a
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• pp.135-135
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• 2008

Various biosensors were evaluated for identifying and detecting foodborne pathogens in a rapid and effective manner. First, five strains of Escherichia coli and six strains of Salmonella were identified using Fourier transform infrared spectroscopy and a statistical program. For doing this, lipopolysaccharides (LPSs) and outer membrane proteins (OMPs) were extracted from a cell wall of each bacterial strain. As a result, each strain was identifed at the level of 97% for E. coli and 100% for Salmonella. Second, E. coli O157:H7, S. Enteritidis, and Listeria monocytogenes were identified by multiplex PCR products from four specific genes of each bacteria using a capillary electrophoresis (CE). Also, ground beef for E. coli O157:H7, lettuce for S. Enteritidis, and hot dog for L. monocytogenes were used to determine the possibility of detecting pathogens in foods. Foods inoculated with respective pathogen were cultivated for six hours and multiplex PCR products were obtained and assessed. The minimum detection levels of tested bacteria were <10 cells/g, <10 cells/g, and $10^4$ cells/g for E. coli O157:H7, S. Enteritidis, and L. monocytogenes, respectively. Third, it was possible to detect S. Typhimurium in a pure culture and lettuce by a bioluminescence-based detection assay using both recombinant bacteriophage P22::luxI and a bioluminescent bioreporter. In addition, bacteriophage T4 was quantitatively monitored using E. coli including luxCDABE genes.

• Journal of Microbiology and Biotechnology
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• v.22 no.6
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• pp.780-787
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• 2012

The maize pathogen Gibberella moniliformis produces fumonisins, a group of mycotoxins associated with several disorders in animals and humans, including cancer. The current focus of our research is to understand the regulatory mechanisms involved in fumonisin biosynthesis. In this study, we employed a proteomics approach to identify novel genes involved in the fumonisin biosynthesis under nitrogen stress. The combination of genome sequence, mutant strains, EST database, microarrays, and proteomics offers an opportunity to advance our understanding of this process. We investigated the response of the G. moniliformis proteome in limited nitrogen (N0, fumonisin-inducing) and excess nitrogen (N+, fumonisin-repressing) conditions by one- and two-dimensional electrophoresis. We selected 11 differentially expressed proteins, six from limited nitrogen conditions and five from excess nitrogen conditions, and determined the sequences by peptide mass fingerprinting and MS/MS spectrophotometry. Subsequently, we identified the EST sequences corresponding to the proteins and studied their expression profiles in different culture conditions. Through the comparative analysis of gene and protein expression data, we identified three candidate genes for functional analysis and our results provided valuable clues regarding the regulatory mechanisms of fumonisin biosynthesis.

• Journal of Animal Science and Technology
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• v.63 no.1
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• pp.194-197
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• 2021

Salmonella enterica is a representative foodborne pathogen in the world. The S. enterica strain K_SA184 was isolated from the lamb (Ovis aries), which was collected from a local traditional market in South Korea. In this study, the S. enterica strain K_SA184 was sequenced using PacBio RS II and Illumina NextSeq 500 platforms. The final complete genome of the S. enterica strain K_SA184 consist of one circular chromosome (4,725,087 bp) with 52.3% of guanine + cytosine (G + C) content, 4,363 of coding sequence (CDS), 85 of tRNA, and 22 of rRNA genes. The S. enterica strain K_SA184 genome includes encoding virulence genes, such as Type III secretion systems and multidrug resistance related genes.