• Journal of Microbiology and Biotechnology
• /
• v.11 no.2
• /
• pp.287-293
• /
• 2001

A fast and easy PCR-SSCP method was developed and assessed for the early detection of rifampin-resistant Mycobacterium leprae in skin biopsy samples from Korean leprosy patients. The 190 bp of the rpoB gene, in which mutation is known to cause resistance to rifampin, was amplified by PCR and then analyzed by SSCP and DNA sequencing, All PCR products showing mobility shift on PCR-SSCP contained mutations, demonstrating that this method can be used for an early diagnositic method to detect a putative rifampin-resistant M. leprae strain. DNA sequence analysis revealed that 19 of 34 patient samples contained M. leprae strains with missense mutations in the rpoB gene: five were the same mutations previously reported to cause rifampin resistance and eight were the new type of mutatios that likely cause rifampin resistance. These newly identified dmutations, whose all five cytosine bases of four amino acids were substitued with thymine, were found at different sites from those reported in Mycobacterium tuberculosis or M. leprae. Therefore, they may provide additional clues to understand the molecular biological basis on the rifampin resistance of M. leprae.

• Tuberculosis and Respiratory Diseases
• /
• v.50 no.1
• /
• pp.29-41
• /
• 2001

Background : The appearance of multiple-drug-resistant Mycobacterium tuberculosis strains has been seriously compromising successful control of tuberculosis. Rifampin-resistance, caused by mutations in the rpoB gene, can be indicative of multiple-drug-resistance, and its detection is of great importance. The present study aimed to develop an oligonucleotide chip for accurate and convenient screening of drug-resistance. Methods : In order to detect point mutations in the rpoB gene, an oligonucleotide chip was prepared by immobilizing specific probe DNA to a microscopic slide glass by a chemical reaction. The probe DNA that was selected from the 81 bp core region of the rpoB gene was designed to have mutation sites at the center. A total of 17 mutant probes related to rifampin-resistance including 8 rifabutin-sensitive mutant probes were used in this study. For accurate determination, wild type probes were prepared for each mutation position with an equal length, which enabled a direct comparison of the hybridization intensities between the mutant and wild type. Results : Mycobacterial genomic DNA from clinical samples was tested with the oligonucleotide chip and the results were compared with those of the drug-susceptibility test in addition to sequencing and INNO-LiPA Rif. TB kit test in some cases. Out of 15 samples, the oligonucleotide chip results of 13 samples showed good agreement with the rifabutin-sensitivity results. The two samples with conflicting result also showed a discrepancy between the other tests, suggesting such possibilities as existence of mixed strains and difference in drug-sensitivity. Further verification of these samples in addition to more case studies are required before the final evaluation of the oligonucleotide chip can be made. Conlcusion : An oligonucleotide chip was developed for the detection of rpoB gene mutations related to drugsusceptibility. The results to date show the potential for using the oligonucleotide chip for accurate and convenient screening of drug-resistance to provide useful information in antituberculosis drug therapy.

• Tuberculosis and Respiratory Diseases
• /
• v.49 no.5
• /
• pp.546-557
• /
• 2000

Background : Oligonucleotide chip technology has proven to be a very useful tool in the rapid diagnosis of infectious disease. Rifampin resistance is considered as a useful marker of multidrug-resistance in tuberculosis. Mutations in the rpoB gene coding $\beta$ subunit of RNA polymerase represent the main mechanism of rifampin resistance. The purpose of this study was to develop a diagnosis kit using oligonucleotide chip for the rapid and accurate detection of rifampin-resistance in Mycobacterium tuberculosis. Method : The sequence specific probes for mutations in the rpoB gene were designed and spotted onto the glass slide, oligonucleotide chip. 38 clinical isolates of Mycobacterium were tested. A part of rpoB was amplified, labelled, and hybridized on the oligonucleotide chip with probes. Results were analyzed with a laser scanner. Direct sequencing was done to verify the results. Result : The low-density oligonucleotide chip design어 to determine the specific mutations in the rpoB gene of M. tuberculosis accurately detected rifampin resistance associated with mutations in 28 clinical isolates. Mutations at codons 531, 526, and 513 were confirmed by direct sequencing analysis. Conclusion : Mutant detection using oligonucleotide chip technology is a reliable and useful diagnostic tool for the detection of multidrug-resistance in M. tuberculosis.

• Korean Journal of Veterinary Research
• /
• v.55 no.1
• /
• pp.31-39
• /
• 2015

The present study was conducted to determine the full rpoB and eight house-keeping gene sequences of 78 and 35, respectively, avian pathogenic E. coli (APEC) strains. Phylogenetic comparison with 66 E. coli and Shigella strains from GenBank and EMBL was also conducted. Based on the full rpoB sequence, 50 different rpoB sequence types (RSTs) were identified. RST 1 was assigned to a major RST that included 34.7% (50/144) of the analyzed strains. RST 2 to RST 50 were then assigned to other strains with higher nucleotide sequence similarity to RST 1 in order. RST 1, 11, and 23 were mixed with APEC along with human commensal and pathogenic strains while RST 2, 6, 9, 13-15, 22, 24, 25, 33, 34, 36, and 41 were unique to APEC strains. Only five APEC strains grouped into RST 32 and 47, which contained human pathogenic E. coli (HPEC). Thus, most of the APEC strains had genetic backgrounds different from HPEC strains. However, the minor APEC strains similar to HPEC should be considered potential zoonotic risks. The resolution power of multi-locus sequence typing (MLST) was better than RST testing. Nevertheless, phylogenetic analysis of rpoB was simpler and more economic than MLST.

• The Journal of the Korean Society for Microbiology
• /
• v.34 no.6
• /
• pp.561-571
• /
• 1999

Diagnosis of mycobacterial infection is dependent upon the isolation and identification of causative agents. The procedures involved are time consuming and technically demanding. To improve the laborious identification process mycobacterial systematics supported by gene analysis is feasible, being particularly useful for slowly growing or uncultivable mycobacteria. To complement genetic analysis for the differentiation and identification of mycobacterial species, an alternative marker gene, rpoB encoding the ${\beta}$ subunit of RNA polymerase, was investigated. rpoB DNAs (342 bp) were amplified from 52 reference strains of mycobacteria including Mycobacterium tuberculosis H37Rv (ATCC 27294) and clinical isolates by the PCR. The nucleotide sequences were directly determined (306 bp) and aligned using the multiple alignment algorithm in the MegAlign package (DNASTAR) and MEGA program. A phylogenetic tree was constructed with a neighborhood joining method. Comparative sequence analysis of rpoB DNA provided the basis for species differentiation. By being grouped into species-specific clusters with low sequence divergence among strains belonging to same species, all the clinical isolates could be easily identified. Furthermore RFLP analysis enabled rapid identification of clinical isolates.

• Journal of the Korean Wood Science and Technology
• /
• v.46 no.4
• /
• pp.402-414
• /
• 2018

Species identification of wood provides important information for archaeology, restoration of cultural assets, preventing illegal logging, and more. Wood species are usually identified based on their anatomical features with the use of a microscope. However, this method may not be able to distinguish between anatomically similar species or subspecies. To overcome this problem, wood species need to be identified at the molecular level using DNA sequencing. However, unlike living plant cells, wood is difficult to pulverize using a mortar, and DNA extraction from dried wood is challenging. To solve these problems, we propose a pretreatment method in which wood is pulverized using 60-grit sandpaper and hydrated with water for 2 days. Using this method, we were able to stably amplify the rpoB gene from the extracted DNA of Pinus rigida. In addition, sequence analysis of the rpoB gene revealed six single nucleotide polymorphisms (SNPs), which classified the rpoB sequences in the genus Pinus into five groups. Our data indicate that although these SNPs were not suitable for species identification, they can potentially be used to determine the origin of different wood subspecies or individual samples of wood.

• Journal of fish pathology
• /
• v.22 no.3
• /
• pp.391-400
• /
• 2009

Genetic identification of 17 fish-derived Aeromonas strains was attempted using 5 housekeeping genes. 16S rRNA, gyrB, rpoD, dnaJ and recA genes from the 17 strains were amplified, and total of 85 amplicons were sequenced. DNA sequences of the strains and type strains of the 17 Aeromonas homology groups were used for genetic identification and phylogenetic analyses. None of the strains was identified as a single species using the 16S rRNA gene, showing the same identities (average = 99.7%) with several Aeromonas species. According to gyrB, rpoD, dnaJ, and recA, 9 strains and RFAS-1 used in this study were identified as A. hydrophila and A. salmonicida, respectively. However, the other strains were closely related to 2 or more Aeromonas species (i.e., A. salmonicida, A. veronii, A. jandaei, A. media and A. troda) depending on the genetic marker used. In this study, gyrB, rpoD, dnaJ and recA gene sequences proved to be advantageous over 16S rRNA for the identification of field Aeromonas isolates obtained from fish. However, there are discrepancies between analyses of different phylogenetic markers, indicating there are still difficulties in genetic identification of the genus Aeromonas using the housekeeping genes used in this study. Advantages and disadvantages of each housekeeping gene should be taken into account when the gene is used for identification of Aeromonas species.

• Korean Journal of Microbiology
• /
• v.32 no.4
• /
• pp.264-270
• /
• 1994

A gene coding for a novel putative $\sigma$ factor of RNA polymerase has been identified from Streptomyces coelicolor A3(2) using Escherichia coli rpoS gene fragment as a probe. The 486 bp rpoS gene fragment was amplified from E. coli genomic DNA by PCR with two synthetic oligonucleotides, the sequences of which were deduced from the amino acid sequences in the regions 2.3 and 4.2 conserved among various bacterial factors. When E. coli genomic DNA fragments were hybridized with cloned rpoS probe, only one band corresponding to rpoS gene (3.2 kb PvuII fragment or 2.3 kb KpnI fragment) was detected. In S. coelicolor, however, two bands were detected both in PvuII digested DNA and SalI digested DNA. 3.5 kb PvuII fragment which binds the rpoS gene probe was cloned (pMS1) from the sublibrary, and the nucleotide sequences of 1.0 kb BamH'/HincII subclone (pBH2) was partially determined. The nucleotide sequences revealed extensive similarity to other $\sigma$ factor genes of S. coelicolor (hrdA, hrdB, hrdC, hrdD), S. aureofaciens (hrdA, hrdB, hrdC, hrdD), Synechococcus species, Pseudomonas aeruginosa, Stigmatella aurantiaca, and Anabaena species. The nucleotide sequences in regions 1.2 and 4 were compared with the corresponding regions of 5 known ${\sigma}$ factor genes of S. coelicolor by multiple alignment. It turned out that the cloned gene is most closely related to hrdA showing 88% amino acid similarity in region 1.2 and 75% in region 4.

• Journal of Microbiology and Biotechnology
• /
• v.29 no.8
• /
• pp.1299-1309
• /
• 2019

As an opportunistic bacterial pathogen, Pseudomonas aeruginosa PAO1 contains two phenazine-producing gene operons, phzA1B1C1D1E1F1G1 (phz1) and phzA2B2C2D2E2F2G2 (phz2), each of which is independently capable of encoding all enzymes for biosynthesizing phenazines, including phenazine-1-carboxylic acid and its derivatives. Other previous study reported that the RpoS-deficient mutant SS24 overproduced pyocyanin, a derivative of phenazine-1-carboxylic acid. However, it is not known how RpoS mediates the expression of two phz operons and regulates pyocyanin biosynthesis in detail. In this study, with deletion of the rpoS gene in the $PA{\Delta}phz1$ mutant and the $PA{\Delta}phz2$ mutant respectively, we demonstrated that RpoS exerted opposite regulatory roles on the expression of the phz1and phz2 operons. We also confirmed that the phz1 operon played a critical role and especially biosynthesized much more phenazines than the phz2 operon when the rpoS gene was knocked out in P. aeruginosa. By constructing the translational reporter fusion vector lasR'-'lacZ and the chromosomal fusion mutant $PA{\Delta}lasR::lacZ$, we verified that RpoS deficiency caused increased expression of lasR, a transcription regulator gene in a first quorum sensing system (las) that activates overexpression of the phz1 operon, suggesting that in the absence of RpoS, LasR might act as an intermediate in overproduction of phenazine biosynthesis mediated by the phz1 operon in P. aeruginosa.

• Korean Journal of Veterinary Research
• /
• v.58 no.1
• /
• pp.51-55
• /
• 2018

Bovine mastitis (BM) has resulted in enormous economic loss in the dairy industry and coagulase-negative staphylococci (CNS) have caused subclinical BM. Although VITEK 2 GP ID card (VITEK 2) has been used for CNS identification, the probability of identification varies. The rpoB sequence typing (RSTing) method has been used for molecular diagnosis and epidemiology of bacterial infections. In this study, we undertook RSTing of CNS and compared the results with those of VITEK2 and 16S rRNA gene sequencing. As compared VITEK2, the molecular-based methods were more reliable for species identification; moreover, RSTing provided more molecular epidemiological information than that from 16S rRNA gene sequencing.