• KSBB Journal
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• v.19 no.1
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• pp.72-77
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• 2004

The aim of this study was to isolate and identify the spoilage bacteria in the low salt cucumber brine. The PCR amplicons comprising a portion of the 16S rRNA gene of the isolated colonies were directly sequenced and the untrimmed whole sequencing results of the unknown strains were aligned with the type strains using BLAST of NCBI. Then Sequence Aligner and Sequence Match of RDP confirmed the outcome. The identified isolates were eight species and belong to three genuses: Clostridium, Lactobacillus, and Bacillus. The RFLP pattern of the 16S rRNA gene of isolates verified the identified species. From now on the complex spoiling process of law salt fermented cucumber could be analyzed using the isolated species individually or with certain combinations.

• Journal of Microbiology and Biotechnology
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• v.20 no.1
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• pp.21-29
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• 2010

The phenolic compounds are a major contaminant class often found in industrial wastewaters and the biological treatment is an alternative tool commonly employed for their removal. In this sense, monitoring microbial community dynamics is crucial for a successful wastewater treatment. This work aimed to monitor the structure and activity of the bacterial community during the operation of a laboratory-scale continuous submerged membrane bioreactor (SMBR), using PCR and RT-PCR followed by denaturing gradient gel electrophoresis (DGGE) and 16S rRNA libraries. Multivariate analyses carried out using DGGE profiles showed significant changes in the total and metabolically active dominant community members during the 4-week treatment period, explained mainly by phenol and ammonium input. Gene libraries were assembled using 16S rDNA and 16S rRNA PCR products from the fourth week of treatment. Sequencing and phylogenetic analyses of clones from the 16S rDNA library revealed a high diversity of taxa for the total bacterial community, with predominance of Thauera genus (ca. 50%). On the other hand, a lower diversity was found for metabolically active bacteria, which were mostly represented by members of Betaproteobacteria (Thauera and Comamonas), suggesting that these groups have a relevant role in the phenol degradation during the final phase of the SMBR operation.

• Korean Journal of Microbiology
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• v.44 no.3
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• pp.251-257
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• 2008

Four potential microcystin-producing cyanobacteria were isolated from large reservoirs which act as sources of drinking water supply in Korea. Strain DC-2, YD-l, and YD-6 were closely related to Microcystis aeruginosa based on the analysis of l6S rRNA gene and mcyA gene sequences. mcyA gene sequence of YDS2-3, isolated from Yongdam Reservoir, was closed to that of M. aeruginosa, whereas l6S rRNA gene sequence was not related to the known sequences of microcystin-producing cyanobacteria indicating this strain can be a novel cyanobacterium belonging to the genus Microcystis. When mcyA gene sequences of isolated cyanobacteria were compared with the mcyA gene sequence library of two reservoirs, the sequence of DC-2 matched with the dominant ones.

• Journal of Microbiology
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• v.45 no.5
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• pp.418-421
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• 2007

The nucleotide at position 791(G791) of E. coli 16S rRNA was previously identified as an invariant residue for ribosomal function. In order to characterize the functional role of G791, base substitutions were introduced at this position, and mutant ribosomes were analyzed with regard to their protein synthesis ability, via the use of a specialized ribosome system. These ribosomal RNA mutations attenuated the ability of ribosomes to conduct protein synthesis by more than 65%. A transition mutation (G to A) exerted a moderate effect on ribosomal function, whereas a transversion mutation (G to C or U) resulted in a loss of protein synthesis ability of more than 90%. The sucrose gradient profiles of ribosomes and primer extension analysis showed that the loss of protein-synthesis ability of mutant ribosomes harboring a base substitution from G to U at position 791 stems partially from its inability to form 70S ribosomes. These findings show the involvement of the nucleotide at position 791 in the association of ribosomal subunits and protein synthesis steps after 70S formation, as well as the possibility of using 16S rRNA mutated at position 791 for the selection of second-site revertants in order to identify ligands that interact with G791 in protein synthesis.

• Journal of Periodontal and Implant Science
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• v.28 no.4
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• pp.691-703
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• 1998

The 16S rRNA analyzing method is a bacterial identification method that is useful in identifying bacteria which is difficult to do by other means. The following 7 types of bacteria which are Treponema, A. actinomycetemcomitans, P. gingivalis, Fusobacterium, B. forsythus, P. intermedia, P. micros were evaluated in order to study their distribution among patients with adult periodontitis. The 16S rRNA analyzing method was used to compare bacterial distribution among 3 groups. Subgingival plaque acquired from the affected sites(pocket depth ${\geq}6mm$) of 29 patients with adult periodontitis were grouped as the experimental group while plaque from the non-affected sites(pocket depth ${\leq}3mm$) were grouped as control 2 and finally plaque acquired from students with healthy periodontal tissues were grouped as control 1. The results are as follows ; 1. The distribution of Treponema was 12.5% for control 1, 21.4% for control 2 and 75.4% for the experimental group. For A. actinomycetemcomitans the distribution was 0.5%, 19.0%, 44.4% in respect to the order of groups mentioned above. P.gingivalis showed 10.5%, 43.1%, 94.0% distribution, Fusobacterium 33.0%, 48.3%, 81.0% distribution, B. forsythus 9.5%, 17.2%, 65.9% distribution, P. intermedia 1.0%, 12.1%, 26.3% distribution and finally P. micros 5.0%, 19.0%, 48.7% respectively. In all 7 types of bacteria, the experimental group showed higher bacterial distribution compared to the other two groups with statistically significant difference. 2. In the case of Treponema, A. actinomycetemcomitans, gingivalis,Fusobacterium, B. forsythus, P. intermedia, P. micros showed significant difference between control 1 and 2. These results suggest that the 16S rRNA analyzing method which was applied on Koreans for the first time could be utilized and useful in finding potential pathogens of periodontal disease.

• Biomedical Science Letters
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• v.9 no.3
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• pp.139-144
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• 2003

Since water borne infection causes acute diseases and results in spread of diseases by secondary infection, the prevention is very important. Therefore, it is necessary to have a method that is rapid and effective to monitor pathogenic bacteria in drinking water. In this study, we employed a systematic method, Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) analysis, to develop an effective monitoring system for possible bacterial contaminants in drinking water. For this purpose, PCR primers were derived from 992 bp region of the 16s rRNA gene that is highly conserved through the different species of prokaryotes. To test whether the PCR primers designed are indeed useful for detecting all the possible microbial contaminants in the water, the primers were used to amplify 16s rRNA regions of different microbial water-borne pathogens such as E. coli, Salmonella, Yersinia, Listeria, and Staphylococcus. As expected, all of tested microorganisms amplified expected size of PCR products indicating designed PCR primers for 16s rRNA indeed can be useful to amplify all different microbial water-borne pathogens in the water. Furthermore, to test whether these 16s rRNA based PCR primers can detect bacterial populations present in the water, water samples taken from diverse sources, such as river, tap, and sewage, were used for amplification. PCR products were for then subjected for cloning into a T-vector to generate a library containing 16s rRNA sequences from various bacteria. With cloned PCR products, RFLP analysis was done using PCR products digested with restriction enzyme such as Hae III to obtain species-specific RFLP profiles. After PCR-RFLP, the bacterial clones which showed the same RFLP profiles were regarded as the same ones, and the clones which showed distinctive RFLP profiles were subsequently subjected for sequence analysis for species identification. By this PCR-RFLP analysis, we were able to reveal diverse populations of bacteria living in water. In brief, in unsterilized natural river water, over 60 different species of bacteria were found. On the other hand, no PCR products were detected in drinking tap-water. The results from this study clearly indicate that the PCR-RFLP-sequence analysis can be a useful method for monitoring diverse, perhaps pathogenic bacteria contaminated in water in a rapid fashion.

• Journal of Korean society of Dental Hygiene
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• v.18 no.5
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• pp.843-852
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• 2018

Objectives: The study aimed to isolate the abundant bacteria in dental caries in children and to investigate the bacterial species involved in addition to those that have been previously reported. Methods: The specimens were collected from the supragingival plaques of each dental caries area, pit and fissure caries, deep dentinal caries, smooth surface caries, and dental caries, and from healthy subjects in the control group. Bacteria were cultured from these specimens, DNA was extracted from the isolated bacteria, and the 16S rRNA gene sequences were analyzed and identified. Results: Based on the results of the 16S rRNA gene sequence analysis for the 90 strains of dominant bacteria from the 45 specimens, 5, 7, 8, 7, and 13 species were identified from the supragingival plaques from healthy teeth, pit and fissure caries, deep dentinal caries, smooth surface caries, and dental caries, respectively. In healthy teeth, Actinomyces naeslundii dominated. Corynebacterium durum, Ralstonia pickettii, and Streptococcus intermedius showed equal distribution. The dominant bacterial species in dental caries, S. sanguinis, showed the greatest difference in prevalence in pit and fissure caries. In deep dentinal caries, S. mutans and Lactobacillus rhamnosus were dominant; in smooth surface caries, S. mutans and S. sanguinis were dominant; and in the supragingival plaques of dental caries, S. sanguinis and S. mutans were dominant. Conclusions: The bacterial species isolated from dental caries encompassed four phyla, eight genera, and 22 species. In addition, the SS1-2 strain, belonging to the genus Neisseria, was identified as a new species from among the isolated strains.

• KSBB Journal
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• v.18 no.1
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• pp.39-44
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• 2003

A Gene content phylogenetic tree and a 16s rRNA based phylogenetic tree were compared for 33 whole-genome sequenced procaryotes, neighbor joining and bootstrap methods (n=1,000). Ratio of conserved COG (clusters of orthologous groups of proteins) to orthologs revealed that they were within the range of 4.60% (Mezorhizobium loti) or 56.57% (Mycopiasma genitalium). This meant that the ratio was diverse among analyzed procaryotes and indicated the possibility of searching for useful genes. Over 20% of orthologs were independent among the same species. The gene content tree and the 16s rDNA tree showed coincidence and discordance in Archaeabacteria, Proteobacteria and Firmicutes. This might have resulted from non-conservative genes in the gene content phylogenetic tree and horizontal gene transfer. The COG based gene content tree could be regarded as a midway phylogeny based on biochemical tests and nucleotide sequences.

• International Journal of Industrial Entomology and Biomaterials
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• v.2 no.1
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• pp.37-53
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• 2001

Two regions of mtDNA genome, cytochrome oxidase subunit I (COI) and 165 ribosomal RNA (165 rRNA) genes, were sequenced for 15 species of the long-horned beetle belonging to four subfamilies and geographic samples of mulberry longicorn beetle, Apriona germari, from two localities in Korea. Ten samples of A. germari collected from Suwon and Busan revealed three COI haplotypes ranging in nucleotide divergence of 0.3% to 0.5%, and the two populations shared one common COI haplotype (80%). The sequence divergence among 15 species of the long-horned beetle was much higher in COI gene (12.3%∼39.4%) than 16S rRNA gene (7.2% to 23.1), and the maximum value in the COI gene is exceptional compared with other relevant studies, including that of Coleoptera. The greatly increased divergence in the COI gene, in facto was stemmed from a peculiar sequence of Prionus insularis belonging to Prioninne, divergence of which ranges from 31.2% to 39.3% from other species. We discussed possible reason of the divergence in this species. Due to the abnormality of COI gene divergence, decrease in phylogenetic signal was severe in COI nucleotide and, subsequently, the converted amino acid sequences, rendering us to put more confidence on the 16S5 rRNA gene data. Although the molecular phylogeny confidently supports the monophyletic origin of Lepturinae, the presence of discrepancy between molecular data and traditional taxonomic views also is a testable hyothesis. One such discrepancy includes taxonomic position of Sophronica obrioides and Theophilea cylindricollis belonging to Lamiinae.

• Journal of Microbiology and Biotechnology
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• v.17 no.8
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• pp.1262-1270
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• 2007

Some hot springs located in the west of Turkey were investigated with respect to the presence of thermophilic microorganisms. Based on phenotyping characteristics and 16S rRNA gene sequence analysis, 16 of the isolates belonged to the genus Geobacillus and grew optimally at about $60^{\circ}C$ on nutrient agar. 16S rRNA gene sequence analysis showed that these isolates resembled Geobacillus species by ${\ge}97%$, but SDS-PAGE profiles of these 16 isolates differ from some of the other species of the genus Geobacillus. However, it is also known that analysis of 16S rRNA gene sequences may be insufficient to distinguish between some species. It is proposed that recN sequence comparisons could accurately measure genome similarities for the Geobacillus genus. Based on recN sequence analysis, isolates 11, IT3, and 12 are strains of G stearothermophilus; isolate 14.3 is a strain of G thermodenitrificans; isolates 9.1, IT4.1, and 4.5 are uncertain and it is required to make further analysis. The presence of xylanase and arabinofuranosidase activities, and their optimum temperature and pH were also investigated. These results showed that 7 of the strains have both xylanase and arabinofuranosidase activities, 4 of them has only xylanase, and the remaning 5 strains have neither of these activities. The isolates 9.1, 7.1, and 3.3 have the highest temperature optima ($80^{\circ}C$), and 7.2, 9.1, AO4, 9.2, and AO17 have the highest pH optima (pH 8) of xylanase. Isolates 7.2, AO4, AC15, and 12 have optimum arabinofuranosidase activities at $75^{\circ}C$, and only isolate AC15 has the lowest pH of 5.5.