• Journal of Biosystems Engineering
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• 제34권4호
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• pp.254-259
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• 2009

Conventional methods for pathogen detection and identification are labor-intensive and take several days to complete. Recently developed biosensors have shown potential for the rapid detection of foodborne pathogens. In this study, an impedimetric biosensor was developed for rapid detection of Salmonella typhimurium. To develop the biosensor, an interdigitated microelectrode (IME) was fabricated by using semiconductor fabrication process. Anti-Salmonella antibodies were immobilized based on either avidin-biotin binding or self assembled monolayer (SAM) on the surface of the IME to form an active sensing layer. To evaluate effect of antibody immobilization methods on sensitivity of the sensor, detection limit of the biosensor was analyzed with Salmonella samples innoculated in phosphate buffered saline (PBS) or food extract. The impedimetric biosensor based on SAM immobilization method produced better detection limit. The biosensor could detect 107 CFU/mL of Salmonella in pork meat extract. This method may provide a simple, rapid, and sensitive method to detect foodborne pathogens.

• Preventive Nutrition and Food Science
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• 제15권3호
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• pp.233-238
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• 2010

The aim of this study was to determine microbiological contamination of fresh-red pepper and packaged-red pepper powder commercially available in South Korea. Thirty-seven fresh-red peppers were collected from 5 farms and 31 packaged-red pepper powders were purchased from retail markets in South Korea. Foodborne pathogens (Escherichia coli, Salmonella spp., Listeria monocytogenes, Staphylococcus aureus and Bacillus cereus), total viable counts, Enterobacteriaceae, coliforms, yeast and mold, and Aspergillus flavus were determined. Detection percentage of contamination of Bacillus cereus in fresh-red pepper was 8.1%, which was lower than the 39% of detection rate in packaged-red pepper powder. The contamination level of Bacillus cereus was 1～3 log CFU/g in packaged-red pepper powder. Escherichia coli was detected in 5.4% of fresh-red pepper samples and was not detected in packaged-red pepper powder. Enterobacteriaceae and coliforms were detected in both of fresh-red pepper and packaged-red pepper powders. Foodborne pathogens, except Bacillus cereus and Escherichia coli, were not detected.

• Journal of Dairy Science and Biotechnology
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• 제29권2호
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• pp.59-68
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• 2011

In Korea, there are a couple of risk assessment organizations: The Animal Plant and Fisheries Quarantine and Inspection Agency(QIA) and the Korea Food and Drug Administration (KFDA). The major food laws include the Food Sanitation Act (FSA), the Livestock Product Processing Act (LPPA), and the Agricultural Products Quality Control Act (APQCA). Milk and dairy products are mostly controlled by the Food Sanitation Act and the Livestock Product Processing Act. This study was carried out to estimate the current standard methods of foodborne pathogens for dairy products, comparing the Livestock Products Processing Act with the Food Sanitation Act. The standard methods of foodborne pathogens for dairy products are composed by growth culture, isolation culture, and identification, however, standard methods of QIA and KFDA are different at the using of medium and inspection stage. Therefore, consolidation of risk management and risk assessment methods are regarded important to provide safe dairy products to consumer.

• Journal of Microbiology and Biotechnology
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• 제31권9호
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• pp.1323-1329
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• 2021

Micro-scale magnetic beads are widely used for isolation of proteins, DNA, and cells, leading to the development of in vitro diagnostics. Efficient isolation of target biomolecules is one of the keys to developing a simple and rapid point-of-care diagnostic. A zinc finger protein (ZFP) is a double-stranded (ds) DNA-binding domain, providing a useful scaffold for direct reading of the sequence information. Here, we utilized two engineered ZFPs (Stx2-268 and SEB-435) to detect the Shiga toxin (stx2) gene and the staphylococcal enterotoxin B (seb) gene present in foodborne pathogens, Escherichia coli O157 and Staphylococcus aureus, respectively. Engineered ZFPs are immobilized on a paramagnetic bead as a detection platform to efficiently isolate the target dsDNA-ZFP bound complex. The small paramagnetic beads provide a high surface area to volume ratio, allowing more ZFPs to be immobilized on the beads, which leads to increased target DNA detection. The fluorescence signal was measured upon ZFP binding to fluorophore-labeled target dsDNA. In this study, our system provided a detection limit of ≤ 60 fmol and demonstrated high specificity with multiplexing capability, suggesting a potential for development into a simple and reliable diagnostic for detecting multiple pathogens without target amplification.

• 산업식품공학
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• 제21권3호
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• pp.191-200
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• 2017

There have been great efforts to develop a rapid and sensitive detection method to monitor the presence of pathogenic bacteria in food. While a number of methods have been reported for bacterial detection with a detection limit to a single digit, most of them are suitable only for the bacteria in pure culture or buffered solution. On the other hand, foods are composed of highly complicated matrices containing carbohydrate, fat, protein, fibers, and many other components whose composition varies from one food to the other. Furthermore, many components in food interfere with the downstream detection process, which significantly affect the sensitivity and selectivity of the detection. Therefore, isolating and concentrating the target pathogenic bacteria from food matrices are of importance to enhance the detection power of the system. The present review provides an introduction to the representative sample preparation strategies to isolate target pathogenic bacteria from food sample. We further describe the nucleic acid-based detection methods, such as PCR, real-time PCR, NASBA, RCA, LCR, and LAMP. Nucleic acid-based methods are by far the most sensitive and effective for the detection of a low number of target pathogens whose performance is greatly improved by combining with the sample preparation methods.

• 한국약용작물학회지
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• 제24권4호
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• pp.303-308
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• 2016

Background: This study aimed to investigate the antioxidat and antimicrobial activities of the methanol extract and its fractions prepared from the roots of Sanguisorba officinalis L. Methods and Results: The antioxidant activities were compared by evaluating the DPPH radical and nitric oxide (NO) scavenging ability. Measurement of DPPH radical scavenging ability showed that the $SC_{50}$ values of the ethyl acetate fraction was $3.85{\mu}g/m{\ell}$. The ethyl acetate fraction exhibited the most effective DPPH radical scavenging ability compared with the other samples. As for the NO scavenging ability, at all tested concentrations, the ethyl acetate fraction showed a higher scavenging activity than that of the extract and other fractions. These results are related to the total phenolic compound and flavonoid contents of the ethyl acetate fraction. Antimicrobial activity against foodborne pathogens was investigated using the disc diffusion assay. The ethyl acetate fraction showed the highest antimicrobial activity against gram-positive Staphylococcus aureus and Bacillus cereus. However, the chloroform fraction had a higher antimicrobial activity against gram-negative Vibrio vulnificus than that of the extract and other fractions. Conclusions: The results show that the ethyl acetate fraction had a higher antioxidant as well as antimicrobial activity, than did the other samples. Therefore, the ethyl acetate fraction has potential application in the food industry.

• 한국식품영양과학회지
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• 제33권3호
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• pp.463-468
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• 2004

병원성 식중독 미생물에 대한 참나무류 6종의 부위 별 항균력을 검색한 결과, 참나무류 부위별 에탄올 추출물의 항균력은 그람양성 세균과 음성 세균에 대해 높은 항균 활성을 나타내었으며, 그람음성균인 E. coli 0157:H7이나 S. typhimurium보다 그람양성균인 B. cereus, L. monocytogenes, S. aureus균에 대하여 더 강한 항균력을 나타내었다. 반면에, 효모와 곰팡이에 대해서는 항균력을 나타내지 않았다. 수종별 항균 활성은 갈참, 떡갈 신갈나무 에탄올 추출물이 졸참, 상수리, 굴참나무 에탄올 추출물보다 더 강하였으며, 부위별로는 잎이 가장 높은 항균활성을 나타내었고 수피와 목질부는 유사한 항균력을 나타내었다. 6종의 부위별 참나무수종 중에서 갈참나무 잎 에탄올 추출물이 가장 강한 항균력을 나타내었으며, B. cereus ATCC 9634와 L. monocytogenes ATCC 19111에서는 500 $\mu\textrm{g}$/mL에서, E. coli O157:H7는 1 mg/mL의 농도에서 생육저해효과를 나타내었다.

• 한국식품위생안전성학회지
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• 제30권1호
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• pp.98-102
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• 2015

Oleanolic acid는 다수의 식물 종에서 분리 되어 왔고 주로 유해한 영향이 없는 과일과 약초에 존재하기 때문에 전세계적으로 많은 나라에서 안전하게 소비되고 있으며, 현재는 화장품이나 약품에 사용되고 있다. Oleanolic acid는 peptidoglycan을 표적으로 하기 때문에 petidoglycan이 세균외막에 덮여있는 그람음성세균인 E. coli, Y. enterocolitica, S. flexneri, S. sonnei와 같은 세균에는 뚜렷한 oleanolic acid 항균활성이 관찰되지 않았다. 하지만 oleanolic acid의 유도체를 사용할 경우 그람음성세균에 대한 항균활성도 증가하였다. 반면 S. aureus와 L. monocytogenes와 같은 그람양성세균의 경우 peptidoglycan층이 세균외막에 덮여 있지 않기 때문에 oleanolic acid에 매우 민감하였다. 또한 oleanolic acid는 사람에 대한 세포독성 실험에서도 그 독성이 낮은 것으로 판단되었기 때문에 식중독 세균제어를 목적으로 연구를 진행할 필요가 있으며, 이 결과들은 식품에 적용되거나 항생제 대체를 위한 치료목적으로도 사용될 수 있을 것으로 사료된다.

• Journal of Biosystems Engineering
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• 제39권4호
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• pp.345-351
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• 2014

Purpose: Rapid detection of bacteria is very important in agricultural and food industries to prevent many foodborne illnesses. The objective of this study was to develop a portable nuclear magnetic resonance (NMR)-based system to detect foodborne pathogens (E. coli). This study was focused on developing a method to detect low concentrations of magnetic nanoparticles using NMR techniques. Methods: NMR relaxometry was performed to examine the NMR properties of iron nanoparticle mixtures with different concentrations by using a 1 T permanent magnet magnetic resonance imaging system. Exponential curve fitting (ECF) and inverse Laplace transform (ILT) methods were used to estimate the NMR relaxation time constants, $T_1$ and $T_2$, of guar gum solutions with different iron nanoparticle concentrations (0, $10^{-3}$, $10^{-4}$, $10^{-5}$, $10^{-6}$, and $10^{-7}M$). Results: The ECF and ILT methods did not show much difference in these values. Analysis of the NMR relaxation data showed that the ILT method is comparable to the classical ECF method and is more sensitive to the presence of iron nanoparticles. This study also showed that the spin-spin relaxation time constants acquired by a Carr-Purcell-Meiboom-Gill (CPMG) pulse sequence are more useful for determining the concentration of iron nanoparticle solutions comparwith the spin-lattice relaxation time constants acquired by an inversion recovery pulse sequence. Conclusions: We conclude that NMR relaxometry that utilizes CPMG pulse sequence and ILT analysis is more suitable for detecting foodborne pathogens bound to magnetic nanoparticles in agricultural and food products than using inversion recovery pulse sequence and ECF analysis.

• 한국미생물·생명공학회지
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• 제47권2호
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• pp.183-194
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• 2019

The consumption of fresh vegetables has been related to recurrent outbreaks of foodborne diseases (FBD) worldwide. Therefore, the development of effective alternative technologies is necessary to improve the safety of these products. This study aimed to isolate and identify epiphytic lactic acid bacteria (LAB) from fresh fruits and leafy vegetables and characterize their antagonistic capacity due to their ability to produce bacteriocins or antibacterial compounds. For this, 92 LAB isolates from fruits and leafy vegetables were screened for antagonistic activity. Two strains with the highest and broadest antagonistic activities were selected for further characterization; one from cantaloupe melon (strain CM175) and one from cilantro leaves (strain C15). The cell-free supernatants (CFS) of CM175 and C15 were found to exhibit antagonistic activity against FBD-causing pathogens. The CM175 and C15 strains were identified as Pediococcus pentosaceus and Lactobacillus graminis, respectively. Notably, the P. pentosaceus CM175 CFS stopped the growth of Salmonella Typhimurium, Salmonella Saintpaul, Staphylococcus aureus, and Listeria monocytogenes, and delayed Escherichia coli O157:H7 growth. Moreover, L. graminis C15 CFS delayed the growth of all indicator pathogens, but did not completely stop it. Organic acids and bacteriocin-like molecules were determined to be possibly exerting the observed antagonistic activity of the identified LAB strains. Thus, application of the antagonistic compounds produced by Pediococcus pentosaceus and Lactobacillus graminis could be a novel and ecological strategy in developing antimicrobial biopreservatives for the food industry and mitigating FBD by reducing the biological contamination in fruit and vegetable orchards, mainly via their potential in controlling both gram-negative and gram-positive pathogenic bacteria.