• Journal of Microbiology and Biotechnology
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• v.29 no.6
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• pp.887-896
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• 2019

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS)-based pathogen identification relies on the ribosomal protein spectra provided in the proprietary database. Although these mass spectra can discern various pathogens at species level, the spectra-based method still has limitations in identifying closely-related microbial species. In this study, to overcome the limits of the current MALDI-TOF MS identification method using ribosomal protein spectra, we applied MALDI-TOF MS of low-mass profiling to the identification of two genetically related Bacillus species, the food-borne pathogen Bacillus cereus, and the insect pathogen Bacillus thuringiensis. The mass spectra of small molecules from 17 type strains of two bacilli were compared to the morphological, biochemical, and genetic identification methods of pathogens. The specific mass peaks in the low-mass range (m/z 500-3,000) successfully identified various closely-related strains belonging to these two reference species. The intensity profiles of the MALDI-TOF mass spectra clearly revealed the differences between the two genetically-related species at strain level. We suggest that small molecules with low molecular weight, 714.2 and 906.5 m/z can be potential mass biomarkers used for reliable identification of B. cereus and B. thuringiensis.

• Food Science and Biotechnology
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• v.18 no.1
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• pp.12-17
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• 2009

The effect of kimchi, traditional Korean fermented vegetables, on inactivating food-borne pathogens and the kimchi factors affecting the antimicrobial activity were investigated. More cells of Listeria monocytogenes, Staphylococcus aureus, Escherichia coli O157:H7, and Salmonella typhimurium were inactivated in the kimchi that had low pH and high titratable acidity. Of the raw ingredients in kimchi, raw garlic showed the strongest antimicrobial activity against the pathogens. When kimchi was fermented at 0, 4, 10, or $20^{\circ}C$ to pH 4.4, higher kimchi fermentation temperature resulted in higher titratable acidity. The greatest inactivation of S. typhimurium occurred in kimchi fermented at $20^{\circ}C$, while L. monocytogenes were inactivated in kimchi fermented at $0^{\circ}C$ in situ. This study showed that appropriately fermented kimchi can inactivate various food-borne pathogens and that the fermentation temperature of the kimchi is an important factor in determining the ability of the kimchi to inactivate specific pathogens. Lactic acid bacteria (LAB) multiplication and organic acids produced according to LAB metabolism play a role in inactivating food-borne pathogens in kimchi.

• Proceedings of the Korean Society of Food Hygiene and Safety Conference
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• 1999.10a
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• pp.1-27
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• 1999

• Journal of Dairy Science and Biotechnology
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• v.31 no.2
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• pp.165-170
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• 2013

Milk and dairy products are not only excellent foods for humans, providing plentiful varied nutrients, but are also a good medium for detrimental food-borne pathogens. Although the food safety field has stabilized due to standardization of food processing, such as the hazard analysis critical control point (HACCP), outbreaks and cases caused by food-borne pathogens still occur at high rates. In approximately 30% of cases, the disease-causing pathogenic organism is undetermined. Recently, a biosensor was developed that has a simple and fast response and overcomes the problems of conventional methods such as cultivation, immuno-assay, polymerase chain reaction, and microarray. Due to the high selectivity and sensitivity of optical biosensors, it is a suitable method for the immediate detection of food-borne pathogens in milk and dairy products.

• Journal of Environmental Health Sciences
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• v.38 no.5
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• pp.415-423
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• 2012

Objectives: This study was performed in order to evaluate antibiotic resistance and analyze the multiple antibiotic resistance of food-borne pathogens isolated from indoor air and an air cleaner at a lunch room in a child care center. Methods: An antibiotic test of food-borne pathogens, including four Staphylococcus aureus and 23 Bacillus cereus was conducted through the disk diffusion method from Clinical and Laboratory Standard Institute. Results: All Staph. aureus was resistant to Ampicillin and Penicillin, while B. cereus was also resistant to Ampicillin, Cefepime and Penicillin. All isolates showed Vancomycin susceptibility but three out of four Staph. aureus and all B. cereus were resistant to Oxacillin. Staph. aureus and B. cereus presented two or more multiple antibiotic resistances. Conclusions: The results indicated that food-borne pathogens isolated from indoor air and an air cleaner at a lunch room in a child care center showed multiple antibiotic resistances. The repeated control of indoor environment quality is required and continuous surveillance of antibiotic resistant strains is demanded.

• Journal of Microbiology and Biotechnology
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• v.26 no.12
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• pp.2030-2035
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• 2016

Bacillus cereus causes food-borne illness through contaminated foods; therefore, its pathogenicity and genome sequences have been analyzed in several studies. We sequenced and analyzed B. cereus strain FORC_021 isolated from a sashimi restaurant. The genome sequence consists of 5,373,294 bp with 35.36% GC contents, 5,350 predicted CDSs, 42 rRNA genes, and 107 tRNA genes. Based on in silico DNA-DNA hybridization values, B. cereus ATCC $14579^T$ was closest to FORC_021 among the complete genome-sequenced strains. Three major enterotoxins were detected in FORC_021. Comparative genomic analysis of FORC_021 with ATCC $14579^T$ revealed that FORC_021 harbored an additional genomic region encoding virulence factors, such as putative ADP-ribosylating toxin, spore germination protein, internalin, and sortase. Furthermore, in vitro cytotoxicity testing showed that FORC_021 exhibited a high level of cytotoxicity toward INT-407 human epithelial cells. This genomic information of FORC_021 will help us to understand its pathogenesis and assist in managing food contamination.

• Journal of Dairy Science and Biotechnology
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• v.31 no.2
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• pp.171-177
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• 2013

The dairy industry has consistently grown via the expansion of dairy-based food categories. Dairy product consumption is stable since the nutrient composition in dairy products is ideal for human health. However, dairy products are highly susceptible to food-borne pathogens. Controlling the safety of dairy products is thus important when considering the nutrient-rich matrix of this food category. Currently, immunoassays or molecular biology techniques have been used to evaluate the safety of dairy products in Korea. These methods are based on the detection of proteins and thus have low reproducibility and sensitivity. Recent techniques to detect food-borne pathogens have focused on genetic analyses. Rapid detection methods for food-borne pathogens in milk and dairy products using polymerase chain reaction (PCR) techniques, such as conventional PCR, real-time PCR, repetitive sequence-based (rep)-PCR, PCR-denaturing gradient gel electrophoresis (DGGE), and digital PCR, are reviewed in this article. The aim of this review was to contribute knowledge of the relationship between microflora and the quality of dairy products. This study will also assist in the immediate monitoring of food-borne pathogens in milk and dairy products when an outbreak related to this food category occurs.

• The Plant Pathology Journal
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• v.35 no.2
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• pp.156-163
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• 2019

Our study investigated the available chlorine content, contact time and difference among strains of each pathogen for sodium hypochlorite (NaOCl) to control chemically against soil-borne fungal pathogens, such as Phytophthora rot by Phytophthora cactorum, violet root rot by Helicobasidium mompa, and white root rot by Rosellinia necatrix, causing die-back symptom on apple trees. As a result, the colony growth of Phytophthora cactorum was inhibited completely by soaking over 5 s in 31.25 ml/l available chlorine content of NaOCl. Those of H. mompa and R. necatrix were inhibited entirely by soaking over 160 s in 62.5 and 125 ml/l available chlorine content in NaOCl, respectively. Also, inhibition effect on available chlorine in NaOCl among strains of each soil-borne pathogen showed no significant difference and was similar to or better than that of fungicides.

• Journal of Microbiology and Biotechnology
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• v.27 no.2
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• pp.262-270
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• 2017

Yersinia enterocolitica is a well-known foodborne pathogen causing gastrointestinal infections worldwide. The strain Y. enterocolitica FORC_002 was isolated from the gill of flatfish (plaice) and its genome was sequenced. The genomic DNA consists of 4,837,317 bp with a GC content of 47.1%, and is predicted to contain 4,221 open reading frames, 81 tRNA genes, and 26 rRNA genes. Interestingly, genomic analysis revealed pathogenesis and host immune evasion-associated genes encoding guanylate cyclase (Yst), invasin (Ail and Inv), outer membrane protein (Yops), autotransporter adhesin A (YadA), RTX-like toxins, and a type III secretion system. In particular, guanylate cyclase is a heat-stable enterotoxin causing Yersinia-associated diarrhea, and RTX-like toxins are responsible for attachment to integrin on the target cell for cytotoxic action. This genome can be used to identify virulence factors that can be applied for the development of novel biomarkers for the rapid detection of this pathogen in foods.

• Food Science and Biotechnology
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• v.15 no.2
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• pp.324-327
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• 2006

The food-borne pathogen Listeria monocytogenes is commonly associated with meats and unpasteurized dairy products. To identify this pathogen in meats more efficiently than has been done in the past, we purchased meats from Korean markets and performed sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and serotyping analysis on Listeria organisms isolated from meat samples. Each Listeria species showed specific protein band patterns on SDS-PAGE. Whole-cell protein SDS-PAGE profiles indicated that the organisms isolated from meats sold in local Korean markets were L. monocytogenes with the serotypes 1/2a, 1/2b, 1/2c, and 4b. We suggest that it is possible to carry out molecular subtyping of L. monocytogenes using SDS-PAGE.