• Microbiology and Biotechnology Letters
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• v.44 no.4
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• pp.470-478
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• 2016

A bacterium producing a large amount of chitinolytic enzyme was isolated from the intestinal tract of earthworm. The isolate was identified as Bacillus licheniformis by 16S ribosomal RNA analysis and designated as B. licheniformis GA9. The enzyme was purified by 40-60% ammonium sulfate precipitation, diethyl-aminoethyl groups exchange chromatography, and gel filtration chromatography. The molecular weight was estimated to be 52.1 kDa and the N-terminal amino acid sequence was D-S-G-K-N-G-K-I-I-R-Y-YP-I-R. The optimum activity of the purified chitinolytic enzyme was shown at pH 5.0 and $40^{\circ}C$, and the enzyme was stable in the ranges of $20-50^{\circ}C$ and pH 5.0-6.0. Enzyme activity was increased by $Co^{2+}$, while it was inhibited by $Cu^{2+}$ and $Fe^{2+}$. But it was recovered by chelating metals with ethylenediaminetetraacetic acid. The $K_m$ and $V_{max}$ values of the purified enzyme were 4.02 mg/ml and 0.52 mg/min, respectively. The chitinolytic enzyme characterized in this study has potential applications in areas such as biotechnology, biomedicine, agriculture, and nutrition.

• Korean Journal of Clinical Laboratory Science
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• v.48 no.3
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• pp.230-236
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• 2016

Economic growth has increased the living standards around the world. Water pollution, in particular, is a public relations issue because it poses a direct threat to everyone's lives. As of recently, the production of taste and odor (T&O) compounds has been a common problem in the water industry. The adsorption process using granular activated carbon (GAC) has been the most widely used process. The objectives of this study were to evaluate the microorganisms before and after the backwashing of GAC and to identify the species of the microorganisms found. Five dominants microorganisms were confirmed after the microfiltration process from backwashing of GAC, and the dominant bacterial species were found to be ${\beta}$-proteobacterium species, Porphyrobacter donghaensis, Polaromonas rhizophaerae, Hydrogenophaga species, and Pseudonocardia species. However, when UV treatment after microfiltration was performed, Hydrogenophaga species and Psedonocardia species were eliminated. Herein, I conclude that the UV treatment post microfiltration process is more efficient than microfiltration process alone. The findings of this study may provide useful information regarding the management of microfiltration process.

• Journal of Periodontal and Implant Science
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• v.53 no.3
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• pp.233-244
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• 2023

Purpose: An implant-supported prosthesis consists of an implant fixture, an abutment, an internal screw that connects the abutment to the implant fixture, and the upper prosthesis. Numerous studies have investigated the microorganisms present on the implant surface, surrounding tissues, and the subgingival microflora associated with peri-implantitis. However, there is limited information regarding the microbiome within the internal screw space. In this study, microbial samples were collected from the supragingival surfaces of natural teeth, the peri-implant sulcus, and the implant-abutment screw hole, in order to characterize the microbiome of the internal screw space in healthy subjects. Methods: Samples were obtained from the supragingival region of natural teeth, the peri-implant sulcus, and the implant screw hole in 20 healthy subjects. DNA was extracted, and the V3-V4 region of the 16S ribosomal RNA was sequenced for microbiome analysis. Alpha diversity, beta diversity, linear discriminant analysis effect size (LEfSe), and network analysis were employed to compare the characteristics of the microbiomes. Results: We observed significant differences in beta diversity among the samples. Upon analyzing the significant taxa using LEfSe, the microbial composition of the implant-abutment screw hole's microbiome was found to be similar to that of the other sampling sites' microbiomes. Moreover, the microbiome network analysis revealed a unique network complexity in samples obtained from the implant screw hole compared to those from the other sampling sites. Conclusions: The bacterial composition of the biofilm collected from the implant-abutment screw hole exhibited significant differences compared to the supra-structure of the implant. Therefore, long-term monitoring and management of not only the peri-implant tissue but also the implant screw are necessary.

• Microbiology and Biotechnology Letters
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• v.49 no.1
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• pp.111-119
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• 2021

A bacterial strain isolated from a Malva verticillata leaf was identified as Bacillus velezensis MV2 based on the 16S rRNA sequencing results. Complete genome sequencing revealed that B. velezensis MV2 possessed a single 4,191,702-bp contig with 45.57% GC content. Generally, Bacillus spp. are known to produce diverse antimicrobial compounds including bacteriocins, polyketides, and non-ribosomal peptides. Antimicrobial compounds in the B. velezensis MV2 were extracted from culture supernatants using hydrophobic interaction chromatography. The crude extracts showed antimicrobial activity against both gram-positive bacteria and gram-negative bacteria; however, they were more effective against gram-positive bacteria. The extracts also showed antifungal activity against phytopathogenic fungi such as Fusarium fujikuroi and F. graminearum. In time-kill assays, these antimicrobial compounds showed bactericidal activity against Bacillus cereus, used as indicator strain. To predict the type of antimicrobial compounds produced by this strain, we used the antiSMASH algorithm. Forty-seven secondary metabolites were predicted to be synthesized in MV2, and among them, fourteen were identified with a similarity of 80% or more with those previously identified. Based on the antimicrobial properties, the antimicrobial compounds may be nonribosomal peptides or polyketides. These compounds possess the potential to be used as biopesticides in the food and agricultural industry as an alternative to antibiotics.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.3
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• pp.434-440
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• 2013

This study was conducted to screen the characteristics and alginate-degrading activity of marine bacterium isolated from brown seaweed (Sargassum thunbergii). The results of 16S ribosomal RNA sequence analysis the strain the genus Vibrio and the strain was subsequently named Vibrio sp. PKA 1003. The optimum culture conditions for the growth of Vibrio sp. PKA 1003 were at pH 7, 3% NaCl, $25^{\circ}C$, and 6% alginic acid, with a 48-hour incubation time. A crude enzyme preparation from Vibrio sp. PKA 1003, showed its highest levels of alginate-degradation activity when cultured at pH 9, $30^{\circ}C$, and 6% alginic acid, with a 63-hour incubation time. Thin layer chromatography analyses confirmed that the crude enzyme released monomers or oligomers from sodium alginate, and results from trypsin treatment showed that the alginate degrading activity depends on this enzyme produced by Vibrio sp. PKA 1003. These results suggest that Vibrio sp. PKA 1003 and its alginate-degrading crude enzyme is useful for the production of alginate oligosaccharides.

• Microbiology and Biotechnology Letters
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• v.39 no.2
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• pp.104-110
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• 2011

Actinomycetes, Gram positive soil bacteria, are valuable microorganisms which produce useful secondary metabolites including antibiotics, antiparasitic substances, anti-cancer drugs, and immunosuppressants. Although a major family of actinomycetes, known as streptomycetes, has been intensively investigated at the molecular level for several decades, a potentially valuable and only recently isolated non-streptomycetes rare actinomycetes (NSRA) family has been poorly characterized due to lack of proper genetic manipulation systems. Here we report that a PCR-based genome screening strategy was performed with approximately 180 independently isolated actinomycetes strains to isolate potentially valuable NSRA strains. Thanks to this simple PCR-based genome screening strategy we were able to identify only seven NSRA strains, followed by 16S rRNA sequencing for confirmation. Through further bioassays, one potentially valuable NSRA strain (tentatively named Nocardiopsis species MMBL010) was identified which possessed both antifungal and antibacterial activities, along with the presence of polyketide synthase and non-ribosomal peptide synthase genes. Moreover, Nocardiopsis species MMBL010, which was intrinsically recalcitrant to genetic manipulation, was successfully transformed via E. coli-driven conjugation. These results suggest that PCR-based genome screening, followed by the establishment of an E. coli-driven conjugation system, is an efficient strategy to maximize potentially valuable compounds and their biosynthetic genes from NSRA strains isolated from various environments.

• Tuberculosis and Respiratory Diseases
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• v.79 no.3
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• pp.165-178
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• 2016

Background: Although recent metagenomic approaches have characterized the distinguished microbial compositions in airways of asthmatics, these results did not reach a consensus due to the small sample size, non-standardization of specimens and medication status. We conducted a metagenomics approach by using terminal restriction fragment length polymorphism (T-RFLP) analysis of the induced whole sputum representing both the cellular and fluid phases in a relative large number of steroid $na{\ddot{i}}ve$ asthmatics. Methods: Induced whole sputum samples obtained from 36 healthy subjects and 89 steroid-$na{\ddot{i}}ve$ asthma patients were analyzed through T-RFLP analysis. Results: In contrast to previous reports about microbiota in the asthmatic airways, the diversity of microbial composition was not significantly different between the controls and asthma patients (p=0.937). In an analysis of similarities, the global R-value showed a statistically significant difference but a very low separation (0.148, p=0.002). The dissimilarity in the bacterial communities between groups was 28.74%, and operational taxonomic units (OTUs) contributing to this difference were as follows: OTU 789 (Lachnospiraceae), 517 (Comamonadaceae, Acetobacteraceae, and Chloroplast), 633 (Prevotella), 645 (Actinobacteria and Propionibacterium acnes), 607 (Lactobacillus buchneri, Lactobacillus otakiensis, Lactobacillus sunkii, and Rhodobacteraceae), and 661 (Acinetobacter, Pseudomonas, and Leptotrichiaceae), and they were significantly more prevalent in the sputum of asthma patients than in the sputum of the controls. Conclusion: Before starting anti-asthmatic treatment, the microbiota in the whole sputum of patients with asthma showed a marginal difference from the microbiota in the whole sputum of the controls.

• The Korea Journal of Herbology
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• v.30 no.3
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• pp.41-47
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• 2015

Objectives : Due to the morphological similarity of the pericarp and description of multi-species in National Pharmacopoeia of Korea and China, the Zanthoxylum Pericarpium is difficult to authenticate adulterant in species levels. Therefore, we introduced the sequence analysis of DNA barcode and identification of single nucleotide polymorphism(SNP) to establish a reliable tool for the distinction of Zanthoxylum Pericarpium from its adulterants. Methods : To analyze DNA barcode region, genomic DNA was extracted from twenty-four specimens of authentic Zanthoxylum species and inauthentic adulterant and the individual internal transcribed spacer regions (rDNA-ITS and ITS2) of nuclear ribosomal RNA gene were amplified using ITS1, ITS2-S2F, and ITS4 primer. For identification of species-specific sequences, a comparative analysis was performed using entire DNA barcode sequences. Results : In comparison of four Zanthoxylum ITS2 sequences, we identified 16, 4, 6, and 4 distinct species-specific nucleotides enough to distinguish Z. schinifolium, Z. bungeanum, Z. piperitum, and Z. simulans, respectively. The sequence differences were available genetic marker to discriminate four species. Futhermore, phylogenetic relationship revealed a clear classification between different Zanthoxylum species showing 4 different clusters. These results indicated that comparative analysis of ITS2 DNA barcode was an useful genetic marker to authenticate Zanthoxylum Pericarpium in species levels. Conclusions : The marker nucleotides, enough to distinguish Z. schinifolium, Z. piperitum, Z. bungeanum, and Z. simulans, were obtained at 30 SNP marker nucleotides from ITS2 sequences. These differences could be used to authenticate official Zanthoxylum Pericarpium from its adulterants as well as discriminating each four species.

• Journal of Microbiology and Biotechnology
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• v.24 no.1
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• pp.106-112
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• 2014

Very few plant growth-promoting rhizobacteria (PGPR) are known to produce gibberellins (GAs). The current study aimed to isolate a phytohormone-producing PGP rhizobacterium from soil and assess its potential to enhance plant growth. The newly isolated bacterium was identified as Leifsonia soli sp. SE134 on the basis of partial 16S ribosomal RNA gene sequence. Application of L. soli culture filtrate significantly increased the biomass, hypocotyl, and root lengths of cucumber seeds as compared with non-inoculated sole medium and distilled water treated controls. Furthermore, the PGPR culture was applied to the GA-deficient mutant rice cultivar Waito-C. Treatment with L. soli SE134 significantly increased the growth of Waito-C rice seedlings as compared with controls. Upon chromatographic analysis of L. soli culture, we isolated, detected and quantified different GAs; namely, $GA_1$ ($0.61{\pm}0.15$), $GA_4$ ($1.58{\pm}0.26$), $GA_7$ ($0.54{\pm}0.18$), $GA_8$ ($0.98{\pm}0.15$), $GA_9$ ($0.45{\pm}0.17$), $GA_{12}$ ($0.64{\pm}0.21$), $GA_{19}$ ($0.18{\pm}0.09$), $GA_{20}$ ($0.78{\pm}0.15$), $GA_{24}$ ($0.38{\pm}0.09$), $GA_{34}$ ($0.35{\pm}0.10$), and $GA_{53}$ ($0.17{\pm}0.05$). Plant growth promotion in cucumber, tomato, and young radish plants further evidenced the potential of this strain as a PGP bacterium. The results suggest that GA secretion by L. soli SE134 might prove advantageous for its ameliorative role in crop growth. These findings can be extended for improving the productivity of different crops under diverse environmental conditions.

• Microbiology and Biotechnology Letters
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• v.42 no.1
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• pp.18-24
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• 2014

This study was conducted to investigate optimum conditions for the production of cellulose-degrading crude enzymes by an isolated marine bacterium. A marine microorganism producing an extracellular cellulose-degrading enzyme was isolated from the red seaweed, Grateloupia elliptica Holmes. The isolated bacterium was identified as Cellulophaga lytica by 16S ribosomal RNA gene sequence analysis and physiological profiling and designated as Cellulophaga lytica PKA 1005. The optimum conditions for the growth of Cellulophaga lytica PKA 1005 were pH 7, 2% NaCl, and $30^{\circ}C$ with 36 h incubation time. To obtain the crude enzyme, the culture medium of the strain was centrifuged for 30 min at $12,000{\times}g$ and $4^{\circ}C$, and the supernatant was used as crude enzyme. The optimum conditions for the production of the cellulose-degrading crude enzyme were pH 8, $35^{\circ}C$, 8% carboxyl methyl cellulose, and 60 h reaction time.