• Journal of Environmental Health Sciences
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• v.45 no.5
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• pp.511-519
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• 2019

Objectives: The standard method for the enumeration of environmental Legionella is culturing, which has several disadvantages, including long incubation and poor sensitivity. The purpose of this study is to demonstrate the usefulness of real-time PCR and to improve the standard method. Methods: In 200 environmental water samples, a real-time PCR and culture were conducted to detect and quantify Legionella. Using with the results of the survey, we compared the real-time PCR with the culture. Results: Each real-time PCR assay had 100% specificity and excellent sensitivity (5 GU/reaction). In the culture, 36 samples were positive and 164 samples were negative. Based on the results of the culture, real-time PCR showed a high negative predictive value of 99%, 35 samples were true positive, 105 samples were true negative, 59 samples were false positive and one sample was a false negative. Quantitative analysis of the two methods indicated a weak linear correlation ($r^2=0.29$, $r^2=0.61$, respectively). Conclusions: Although it is difficult to directly apply quantitative analysis results of real-time PCR in the enumeration of environmental Legionella, it can be used as a complementary means of culturing to rapidly screen negative samples and to improve the accuracy of diagnosis.

• Journal of Plant Biotechnology
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• v.47 no.4
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• pp.309-315
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• 2020

Advances in biotechnology have led to progress in crop genetic engineering to improve agricultural productivity. The use of genetically modified (GM) crops has increased, as have consumers' and regulators' concerns about the safety of GM crops to human health, and ecological biodiversity. As such, the identification of GM crops is a critical issue for developers and distributors, and their labeling is mandatory. Multiplex polymerase chain reaction (PCR) has been developed and its use validated for the detection and identification of GM crops in quarantine. Herein, we established a simultaneous detection method to identify four GM maize events. Event-specific primers were designed between the junction region of transgene and genome of four GM maize lines, namely 5307, DAS-40278-9, MON87460, and MON87427. To verify the efficiency and accuracy of the multiplex PCR we used specificity analysis, limit of detection evaluation, and mixed certified reference materials identification. The multiplex PCR method was applied to analyze 29 living, modified maize volunteers collected in South Korea in 2018 and 2019. We performed multiplex PCR analysis to identify events and confirmed the result by simplex PCR using each event-specific primer. As a result, rather than detecting each event individually, the simultaneous detection PCR method enabled the rapid analysis of 29 GM maize volunteers. Thus, the novel multiplex PCR method is applicable for living modified organism volunteer identification.

• Korean Journal of Plant Taxonomy
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• v.41 no.2
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• pp.119-129
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• 2011

Phylogenetic studies were conducted to evaluate the taxonomic relationships among 27 taxa, including 2 outgroups of Korean Campanulaceae, using PCR-RFLP analysis and ITS sequences. In the PCR-RFLP analysis, 15 restriction endonucleases produced 244 restriction sites and size variations from the chloroplast DNA, and 59 restriction sites (24%) showed polymorphism. The length of the ITS regions ranged from 588 bp to 797 bp. The sequence divergence including the outgroups is 0-39.36%. Phylogenetic analyses based on PCR-RFLP and ITS data suggest that Campanulaceae is monophyletic; Codonopsis and Platycodon forms an independent clade; the Peracarpa and Asyneuma clade is a sister to the Adenophora-Hanabusaya clade; Campanula is monophyletic; and Wahlenbergia basally branches within the ITS tree, whereas they are placed between Campanula and the Codonopsis-Platycodon clade in the PCR-RFLP tree; Hanabusaya is placed within the Adenophora clade; and Adenophora is paraphyletic and shows discordance to the infrageneric classifications based on morphological data. The present results show two data sets, largely congruent at the generic level, but their phylogenetic positions, in particular the Wahlenbergia and Hanabusaya and the infrageneric classifications in Adenophora, show some incongruence.

• Pediatric Infection and Vaccine
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• v.23 no.3
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• pp.194-201
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• 2016

Purpose: Monitoring pneumococcal carriage rates is important. We developed and evaluated the accuracy of a real-time reverse transcription polymerase chain reaction (RT-PCR) protocol for the detection of Streptococcus pneumoniae. Methods: In October 2014, 157 nasopharyngeal aspirates were collected from patients aged <18 years admitted to Chung-Ang University Hospital. We developed and evaluated a real-time PCR method for detecting S. pneumoniae by comparing culture findings with the results of the real-time PCR using genomic DNA (gDNA). Of 157 samples, 20 specimens were analyzed in order to compare the results of cultures, real-time PCR, and real-time RT-PCR. Results: The concordance rate between culture findings and the results of real-time PCR was 0.922 (P<0.01, Fisher exact test). The 133 culture-negative samples were confirmed to be negative for S. pneumoniae using real-time PCR. Of the remaining 24 culture-positive samples, 21 were identified as S. pneumonia -positive using real-time PCR. The results of real-time RT-PCR and real-time PCR from 20 specimens were consistent with culture findings for all S. pneumoniae -positive samples except one. Culture and real-time RT-PCR required 26.5 and 4.5 hours to perform, respectively. Conclusions: This study established a real-time RT-PCR method for the detection of pneumococcal carriage in the nasopharynx. Real-time RT-PCR is an accurate, convenient, and time-saving method; therefore, it may be useful for collecting epidemiologic data regarding pneumococcal carriage in children.

• Journal of Dairy Science and Biotechnology
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• v.39 no.2
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• pp.51-62
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• 2021

Escherichia coli are the predominant facultative bacteria found in the gastrointestinal tract of animals and humans. Some strains of E. coli that acquire virulence factors and cause foodborne and waterborne diseases in humans are called pathogenic E. coli and can be divided into five pathotypes according to the virulence mechanism: EAEC, EHEC, EIEC, EPEC, and ETEC. Although selective media have been developed to detect E. coli, distinguishing pathogenic strains from non-pathogenic ones is difficult because of their similar biochemical properties. Therefore, it is very important to find a new and effective diagnostic method to identify pathogenic E. coli. With recent advances in molecular biology and whole genome sequencing, the use of polymerase chain reaction (PCR) is increasing rapidly. In this review paper, we provide an overview of pathogenic E. coli and present a review on PCR detection methods that can be used to diagnose pathogenic E. coli. In addition, the possibility of real-time PCR incorporating IAC is introduced. Consequently, this review paper will contribute to solving the current challenges related to the detection of pathogenic E. coli.

• The Plant Pathology Journal
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• v.30 no.4
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• pp.440-444
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• 2014

Iris yellow spot virus (IYSV) is a plant pathogenic virus which has been reported to continuously occur in onion bulbs, allium field crops, seed crops, lisianthus, and irises. In South Korea, IYSV is a "controlled" virus that has not been reported, and inspection is performed when crops of the genus Iris are imported into South Korea. In this study, reverse-transcription polymerase chain reaction (RT-PCR) and nested PCR inspection methods, which can detect IYSV, from imported crops of the genus Iris at quarantine sites, were developed. In addition, a modified positive plasmid, which can be used as a positive control during inspection, was developed. This modified plasmid can facilitate a more accurate inspection by enabling the examination of a laboratory contamination in an inspection system. The inspection methods that were developed in this study are expected to contribute, through the prompt and accurate inspection of IYSV at quarantine sites to the plant quarantine in South Korea.

• Biomedical Science Letters
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• v.14 no.2
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• pp.115-118
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• 2008

Salmonella typhi is frequent causes of foodborne illness and its detection is important for monitoring disease progression. In this study, by using general PCR and novel LAMP (Loop Mediated Isothermal Amplification) assay, we evaluated the usefulness of LAMP assay for detection of Salmonella typhi. In this LAMP assay, forward inner primer (FIP) and back inner primer (BIP) was specially designed for recognizing target invA gene. Target DNA was amplified and visualized as ladder-like pattern of bands on agarose gel within 60 min under isothermal conditions at $65^{\circ}C$. When the sensitivity and reproducibility of LAMP were compared to general PCR, there was no difference of reproducibility but sensitivity of LAMP assay was more efficient than PCR (the detection limit of LAMP assay was 30 fg, while the PCR assay was 3 pg). These results indicate that the LAMP assay is a potential and valuable means for detection of Salmonella typhi, especially for its rapidity, simplicity and low cost.

• BMB Reports
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• v.35 no.2
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• pp.248-250
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• 2002

Discrimination between the amplification of mRNA and contaminating genomic DNA is a common problem when performing a reverse transcriptase-polymerase chain reaction (RT-PCR). Even after treatment of the samples with DNAse, it is possible that negative controls (samples in which no reverse transcriptase was added) will give positive results. This indicates that there was amplification of DNA, which was not generated during the reverse transcriptase step. The possibility exists that Taq DNA polymerase acts as a reverse transcriptase, generating cDNA from RNA during the PCR step. In order to test this hypothesis, we incubated samples with a DNAse-free RNAse after the cDNA synthesis. Comparison of the results that were obtained from these samples (incubated with or without DNAse-free RNAse) confirms that the reverse transcriptase activity of Taq DNA polymerase I is a possible source of false positive results when performing RT-PCR from intronless genes. Moreover, we describe here a simple and rapid method to overcome the false positive results that originate by this activity of Taq polymerase.

• BMB Reports
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• v.40 no.1
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• pp.7-14
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• 2007

Helicases are ubiquitous enzymes, which utilize the energy liberated during nucleotide triphosphate hydrolysis to separate double-stranded nucleic acids into single strands. These enzymes are very attractive targets for the development of new antibacterial compounds. The PcrA DNA helicase from Staphylococcus aureus is a good candidate for drug discovery. This enzyme is unique in the genome of S. aureus and essential for this bacterium. Furthermore, it has recently been published that it is possible to identify inhibitors of DNA helicases such as PcrA. In this report, we study the properties of recombinant PcrA from S. aureus purified from Escherichia coli to develop ATPase and helicase assays to screen for inhibitors.

• Journal of Microbiology
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• v.41 no.2
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• pp.157-160
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• 2003

To estimate genetic relationships within the genus Rhizopus, genetic variations in 20 strains were investigated by DGGE and PCR-RFLP of rDNA ITS region (ITSI, ITS2,5.8S). The size of the amplified products showed the interspecific polymorphisms, 650 bp,700 bp, and 900 bp. The DGGE approach allowed the separation of PCR amplicons of the same length according to their sequence variations. When the rDNA ITS region was digested with six restriction enzymes, 20 strains were classified into five RFLP haplotypes. The range of similarity between the 20 strains by PCR-RFLP was 42.3-100%. Based on the results of DGGE aud PCR-RFLP, the 20 strains were divided into four groups, R. oryzae, R. stolonifer, R. microsporus and R. homothallicus. Further study of R. homothallicus is required.