• 미생물학회지
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• 제50권2호
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• pp.158-163
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• 2014

된장으로부터 mannanase 생산균으로 산성 배지에서 분리된 YB-1402는 그람양성 간균으로 포자를 형성하며, 16S rDNA 염기서열과 생화학적 성질이 Bacillus amyloliquefaciens와 가장 높은 유사도를 보였다. 분리균 YB-1402는 konjac을 3% 첨가한 LB 액체배지에서 약 150 U/ml의 최대 mannanase 생산성을 보였다. 분리균의 배양상등액을 사용하여 SDS-PAGE 활성염색을 실시한 결과 분자량이 약 38 kDa로 추정되는 한 종류의 mannanase만이 관찰되었으며, $55^{\circ}C$와 pH 5.5 반응조건에서 mannanase의 최대활성을 보였다. 특히 mannanase는 pH 3.0-10의 범위에서 1시간 방치하였을 때 실활되지 않은 특성을 지니고 있었다. Locust bean gum과 mannooligosaccharides를 mannanase로 분해하였을 때 mannose, mannobiose와 mannotriose가 최종 분해산물로 관찰되었으며 mannotriose 이상의 중합도를 갖는 mannooligosaccharides를 분해하는 것으로 확인되었다.

• 미생물학회지
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• 제40권2호
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• pp.115-120
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• 2004

시안세균(Anabaena cylindrica)의 생장을 효과적으로 억제하는 세균을 분리하여 NG-2로 구분하였다. 이 세균은 그람 음성의 막대형 세균으로서 1.3∼$1.8{\times}0.35{\mu}m$ 정도의 크기를 보였으며, 카탈라제와 옥시다제 양성 반응을 나타내었고, 35∼$40^{\circ}C$아 pH 9.0의 적정생장 조건을 보였다. A.cylindrica의 NG-2를 JM 배지에서 혼합배양할 경우 두 미생물군은 서로 반비례적으로 성장하였으며, 24시간 이내에 A. cylindrica의 영양세포가 거의 완전히 소멸하였다. NG-2는 빛이 있는 조건에서만 효과적으로 A. cylindrica를 분해하였는데, 이는 NG-2의 A. cylindrica 분해활성이 숙주의 광합성 작용에 매우 의존적임을 의미한다. 분리세균의 A. cylindlica 분해작용을 현미경으로 관찰한 결과 NG-2는 숙주세포에 부착하지 않고 배지 내에 산재한 상태에서 영양세포를 분해하였으며, 이형세포는 분해되지 않았다. 또한 영양세포의 세포벽이 분해되면 분해세균들이 filament 주위에 집중적으로 부착하는 콜로니를 형성함으로써 A. cylindrica를 완전히 분해하는 것이 확인되었다. A. cylindrica에 대한 NG-2의 분해활성은 인공배지 뿐만 아니라 강물에서도 유사한 결과를 나타내었다. 또한 발포 polystyrene 재질의 bead에 세균을 부착함으로써 A. cylindrica 분해 효율을 더 상승시킬 수 있었다.

• 한국생명과학회:학술대회논문집
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• 한국생명과학회 2000년도 제28회 학술심포지엄
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• pp.3-8
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• 2000

The complete genome sequence of a Gram-positive bacterium .Bacillus subtilis has recently been reported and it is now clear that more than 50% of its ORFs have no known function (1). To study the global gene expression in B. subtilis at single gene resolution, we have tested the glass DNA microarrays in a step-wise fashion. As a preliminary experiment, we have created arrays of PCR products for 14 ORF whose transcription patterns have been well established through transcriptional mapping analysis. We measured changes in mRNA transcript levels between early exponential and stationary phase by hybridizing fluorescently labeled cDNA (with Cy3-UTP and Cy5-UTP) onto the array. We then compared the microarray data to confirm that the transcription patterns of these genes are well consistent with the known Northern analysis data. Since the preliminary test has been successful, we scaled up the experiments to ${\sim}$94% of the 4,100 annotated ORFs for the complete genome sequence of B. subtilis. Using this whole genomic microarray, we searched genes that are catabolite-repressive and those that are under the control of ${\sigma}^{Y}$, one of the functionally unknown ECF sigma factors. From these results, we here report that we have established DNA microarray techniques that are applicable for the whole genome of B. subtilis.

• Journal of Microbiology and Biotechnology
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• 제8권6호
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• pp.606-612
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• 1998

A microbial flocculant-producing gram-positive bacterium, strain TE11, was isolated from soil samples, and was identified as Bacillus subtilis by using the Midi system, the Biolog system, 16S rDNA sequence analysis, and some physiological and morphological characteristics. The maximum flocculant capsular biopolymer of TE11 strain (BCP, 4.9mg/ml) was obtained when it was grown in GA broth medium containing 3% glutamic acid, 2% glycerol, 0.5% citric acid, 0.5% $NH_4$Cl, 0.05% $MgSO_4.7H_2O,\; 0.05%\;K_2HPO_4\;,\; and\; 0.004%\; FeC1_3. 6H_2O,\; pH 7.2,\; at\; 30^{\circ}C$ for 70 h with shaking. When glycerol was used as an additional carbon source in the GA medium, TE11 produced only flocculant BCP without any by-product. The flocculant (BCP) was found to aggregate suspended kaolin and activated charcoal powder without cations, and its flocculating activity was significantly enhanced by the addition of bivalent cations such as $Ca^{2＋}.Zn^{2},\; and\; Mn^{2＋}$. The flocculation activity by addition of $Ca^{2+}$ was high in an acidic pH 4.0. In the case of $Zn^{2＋}$, high flocculating activity remained without significant loss in the broad range of pH 4.0 to 9.0.

• Journal of Microbiology and Biotechnology
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• 제10권4호
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• pp.522-528
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• 2000

A total of about 300 fungal isolates from forest havitats were screened for inhibitors of tobacco mosaic virus (TMV) infection using its local lesion host, Nicotiana tabacum cv. Xanthi nc. Ine of the isolates, 14T, showed a strong activity against TMV infection, and was identified as an Apiocrea sp. based on its morphological characterstics. Rice was an optimum culture medium for its fermentation, and two antiviral compounds, KGT 141 and KGT 142, were resolved from the rice culture through column chromatography, TLC, and HPLC. By NMR and FAB-MS, the two compounds were identified as chrysospermins B (KGT 141) and D (KGT 142), both of which are peptaibols with 19-mer amino acids possessing an acetylated N-terminus and a hydroxy-amino acid (tryptophanol) at the C-terminus. Both compounds showed inhibitory activities against TMV infection, but chrysospermin D showed the stronger activity than chrysospermin B. The former of $100{\;}\mu\textrm{g}/ml$ and 54.7% at $10{\;}\mu\textrm{g}/ml$, respectively. Furthermore, the chrysospermins were highly cytotoxic toward cancer cell lines of PC-3 (prostrate) and K562 (leukemia), and inhibited growth of the Gram-positive bacteria tested, especially the plant pathogenic bacterium Corynebacterium lilium. To the best of our knowledge, this is the first report on the inhibition of plant virus infection by antimicrobial peptaibols.

• Journal of Microbiology and Biotechnology
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• 제27권1호
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• pp.19-25
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• 2017

Staphylococcus aureus (S. aureus) is a common gram-positive bacterium that causes serious infections in humans and animals. With the continuous emergence of methicillin-resistant S. aureus (MRSA) strains, antibiotics have limited efficacy in treating MRSA infections. Accordingly, novel agents that act on new targets are desperately needed to combat these infections. S. aureus alpha-hemolysin plays an indispensable role in its pathogenicity. In this study, we demonstrate that sclareol, a fragrant chemical compound found in clary sage, can prominently decrease alpha-hemolysin secretion in S. aureus strain USA300 at sub-inhibitory concentrations. Hemolysis assays, western-blotting, and RT-PCR were used to detect the production of alpha-hemolysin in the culture supernatant. When USA300 was co-cultured with A549 epithelial cells, sclareol could protect the A549 cells at a final concentration of $8{\mu}g/ml$. The protective capability of sclareol against the USA300-mediated injury of A549 cells was further shown by cytotoxicity assays and live/dead analysis. In conclusion, sclareol was shown to inhibit the production of S. aureus alpha-hemolysin. Sclareol has potential for development as a new agent to treat S. aureus infections.

• Journal of Microbiology and Biotechnology
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• 제16권11호
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• pp.1728-1733
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• 2006

A Gram-negative, strictly aerobic, nonmotile, and nonspore-forming bacterial strain, designated $T5-12^T$, was isolated from compost and characterized using a polyphasic taxonomical approach. The isolate was positive for catalase and oxidase tests. It could degrade DNA, but was negative for degradation of macromolecules such as casein, collagen, starch, chitin, cellulose, and xylan. The DNA G+C content was 36.0 mol%. The predominant isoprenoid quinone was menaquinone 7 (MK-7). The major fatty acids were $iso-C_{15:0}$ (45.6%), $iso-C_{17:0}$ 3OH (17.2%), and summed feature 4 ($C_{16:0}\;{\omega}7c$ and/or $iso-C_{15:0}$ 2OH, 14.9%). Comparative 16S rRNA gene sequence analysis showed that strain $T5-12^T$ fell within the radiation of the cluster comprising members of the genus Sphingobacterium. Strain $T5-12^T$ exhibited lower than 94% of 16S rRNA gene sequence similarity with respect to the type strains of recognized Sphingobacterium species. On the basis of its phenotypic properties and phylogenetic distinctiveness, strain $T5-12^T$ ($=KCTC\;12578^T=LMG\;23401^T=CCUG\;52467^T$) should be classified in the genus Sphingobacterium as the type strain of a novel species, for which the name Sphingobacterium composti sp. novo is proposed.

• Journal of Microbiology and Biotechnology
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• 제25권7호
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• pp.1007-1014
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• 2015

Plectasin, the first defensin extracted from a fungus (the saprophytic ascomycete Pseudoplectania nigrella), is attractive as a prospective antimicrobial agent. The purpose of this study was to establish a bacterium-based production system and evaluate the antimicrobial activity of the resulting plectasin. A gene encoding plectasin, with the codon preference of Escherichia coli, was optimized based on its amino acid sequence, synthesized using genesplicing with overlap extension PCR, and inserted into the expression vector pGEX-4T-1. The fusion protein was expressed in the soluble fraction of E. coli and purified using glutathione Stransferase affinity chromatography. Plectasin was cleaved from the fusion protein with thrombin and purified by ultrafiltration. The purified plectasin showed strong, concentrationdependent antimicrobial activity against gram-positive bacteria, including antibiotic-resistant bacteria, especially penicillin-resistant Enterococcus faecium. This antimicrobial activity was equal to chemically synthesized plectasin and was maintained over a wide range of pH and temperatures. This soluble recombinant expression system in E. coli is effective for producing plectasin at a relatively lower cost, and higher purity and efficiency than prior systems, and might provide a foundation for developing a large-scale production system. Overall, plectasin shows potential as a novel, high-performance, and safe antibiotic for the treatment of refractory diseases caused by drug-resistant bacterial strains.

• Journal of Microbiology and Biotechnology
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• 제18권2호
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• pp.189-193
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• 2008

A Gram-positive and endospore-forming strain, $JH8^T$, was isolated from deep-sea sediment and identified as a member of the genus Paenibacillus on the basis of 16S rRNA gene sequence and phenotypic analyses. According to a phylogenetic analysis, the most closely related species was Paenibacillus wynnii LMG $22176^T$ (96.9%). Strain $JH8^T$ was also facultatively anaerobic and grew optimally at $20-25^{\circ}C$. The major cellular fatty acid was anteiso-$C_{15:0}$, and the DNA G+C content was 53.1mol%. The DNA-DNA relatedness between the isolate and Paenibacillus wynnii LMG $22176^T$ was 7.6%, indicating that strain $JH8^T$ and P. wynnii belong to different species. Based on the phylogenetic, phenotypic, and chemotaxonomic characteristics, strain $JH8^T$ would appear to belong to a novel species, for which the name Paenibacillus donghaensis sp. novo is proposed (type strain=KCTC $13049^T=LMG\;237S0^T$).

• Journal of Microbiology and Biotechnology
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• 제23권10호
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• pp.1357-1364
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• 2013

Human skin is continuously exposed to ultraviolet (UV)-induced photoaging. UVA increases the activity of MMP-1 in dermal fibroblasts through mitogen-activated protein kinase (MAPK), p38, signaling. The irradiation of keratinocytes by UVA results in the secretion of the inflammatory cytokine, tumor necrosis factor-${\alpha}$ (TNF-${\alpha}$), and the stimulation of MMP-1 in normal human dermal fibroblasts (NHDFs). Lipoteichoic acid (LTA) is a component of the cell wall of gram-positive Lactobacillus spp. of bacteria. LTA is well known as an anti-inflammation molecule. LTA of the bacterium Lactobacillus plantarum has an anti-photoaging effect, but the potential anti-photoaging effect of the other bacteria has not been examined to date. The current study showed that L. sakei LTA (sLTA) has an immune modulating effect in human monocyte cells. Our object was whether inhibitory effects of sLTA on MMP-1 are caused from reducing the MAPK signal in NHDFs. It inhibits MMP-1 and MAPK signaling induced by UVA in NHDFs. We also confirmed effects of sLTA suppressing TNF-${\alpha}$ inducing MMP-1 in NHDFs.