• Molecules and Cells
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• 제38권12호
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• pp.1086-1095
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• 2015

The psychrophilic organism Colwellia psychrerythraea strain 34H produces extracellular polysaccharide substances to tolerate cold environments. Sedoheptulose 7-phosphate isomerase (GmhA) is essential for producing $\small{D}$-glycero-$\small{D}$-mannoheptose 7-phosphate, a key mediator in the lipopolysaccharide biosynthetic pathway. We determined the crystal structure of GmhA from C. psychrerythraea strain 34H (CpsGmhA, UniProtKB code: Q47VU0) at a resolution of $2.8{\AA}$. The tetrameric structure is similar to that of homologous GmhA structures. Interestingly, one of the catalytic residues, glutamate, which has been reported to be critical for the activity of other homologous GmhA enzymes, is replaced by a glutamine residue in the CpsGmhA protein. We also found differences in the conformations of several other catalytic residues. Extensive structural and sequence analyses reveal that CpsGmhA shows high similarity to Escherichia coli DnaA initiatorassociating protein A (DiaA). Therefore, the CpsGmhA structure reported here may provide insight into the structural and functional correlations between GmhA and DiaA among specific microorganisms.

• Journal of Ginseng Research
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• 제41권2호
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• pp.180-187
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• 2017

Background: The incidence of halitosis has a prevalence of 22-50% throughout the world and is generally caused by anaerobic oral microorganisms, such as Fusobacterium nucleatum, Clostridium perfringens, and Porphyromonas gingivalis. Previous investigations on the structure-activity relationships of ginsenosides have led to contrasting results. Particularly, the antibacterial activity of less polar ginsenosides against halitosis-related bacteria has not been reported. Methods: Crude saponins extracted from the Panax quinquefolius leaf-stem (AGS) were treated at $130^{\circ}C$ for 3 h to obtain heat-transformed saponins (HTS). Five ginsenoside-enriched fractions (HTS-1, HTS-2, HTS-3, HTS-4, and HTS-5) and less polar ginsenosides were separated by HP-20 resin absorption and HPLC, and the antimicrobial activity and mechanism were investigated. Results: HPLC with diode-array detection analysis revealed that heat treatment induced an extensive conversion of polar ginsenosides (-Rg1/Re, -Rc, -Rb2, and -Rd) to less polar compounds (-Rg2, -Rg3, -Rg6, -F4, -Rg5, and -Rk1). The antimicrobial assays showed that HTS, HTS-3, and HTS-4 were effective at inhibiting the growth of F. nucleatum, C. perfringens, and P. gingivalis. Ginsenosides-Rg5 showed the best antimicrobial activity against the three bacteria, with the lowest values of minimum inhibitory concentration and minimum bactericidal concentration. One major reason for this result is that less polar ginsenosides can more easily damage membrane integrity. Conclusion: The results indicated that the less polar ginsenoside-enriched fraction from heat transformation can be used as an antibacterial agent to control halitosis.

• Ocean and Polar Research
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• 제23권4호
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• pp.401-410
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• 2001

Global climate change will alter many such properties of the Southern Ocean as temperature, circulation, stratification, and sea-ice extent. Such changes are likely to influence the species composition and activity of Antarctic marine microorganisms (protists and bacteria) which playa major role in deter-mining the concentration of atmospheric $CO_2$ and producing precursors of cloud condensation nuclei. Direct impacts of climate change on Antarctic marine microorganisms have been determined for very few species. Increasing water temperature would be expected to result in a southward spread of pelagic cyanobacteria, coccolithophorids and others. Growth rates of many species would be expected to increase slightly but nutrient limitation, especially micronutrients, is likely to result in a negligible increase in biomass. The extent of habitats would be reduced for those organisms presently living close to the upper limit of their thermal tolerance. Increased UVB irradiance is likely to favour the growth of those organisms tolerant of UVB and may change the trophic structure of marine communities. Indirect effects, especially those as a consequence of a diminution of the amount of sea-ice and increased upper ocean stratification, are predicted to lead to a change in species composition and impacts on both trophodynamics and vertical carbon flux.

• 미생물학회지
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• 제46권1호
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• pp.73-79
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• 2010

극지연구소(KOPRI)는 국내외적으로 유일하게 남북극 지역에서 분리한 저온적응성 박테리아 균주를 대상으로 culture collection(약 6,300균주)을 구축하여 운영하고 있다. 보유 중인 프로테아제(protease) 생산 균주들(총 874균주) 중에서 활성이 높은 프로테아제를 생산하는 78개의 균주들을 1차 선발한 후, 1% skim milk가 포함된 0.1${\times}$ ZoBell 고체배지에 접종하고 다양한 온도($5-30^{\circ}C$)에서 배양하면서 세포외분비성 프로테아제의 활성을 비교하였다. 위의 신속하고 직접적인 균주 스크리닝 방법을 통해서, 최종적으로 저온활성 프로테아제를 생산하는 15개의 저온적응성 균주들을 선발하였다. 최종 선발된 균주들은 16S rRNA 유전자의 분석결과 Pseudoalteromonas (13균주)와 Flavobacterium (2균주) 속(genus)으로 분류되었고, $5-15^{\circ}C$ 저온에서도 활성을 나타내는 저온성 프로테아제를 생산하였다. 15개 균주들이 생산하는 각각의 프로테아제는 특이적 화합물에 의한 효소활성 억제 정도에 따라 5개의 그룹(serine protease, aspartic protease, cysteine protease, metalloprotease, 그리고 미분류 프로테아제)으로 분류되었다. 본 실험을 통해서 선발한 남북극 유래 박테리아 균주들은 새로운 저온활성 프로테아제를 발굴하기 위한 유용한 생물자원으로서의 가치를 가지고 있다.

• Natural Product Sciences
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• 제5권3호
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• pp.151-153
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• 1999

(+)-Hernandulcin is a sweet bisabolane-type sesquiterpene first isolated from Lippia dulcis Trev. (Verbenaceae). This oily compound is 1000-1500 times sweeter than sucrose but with poor solubility in water. Microbial transformation was employed to improve its water solubility, and a variety of microorganisms were screened for their ability to convert (+)-hernandulcin to more polar metabolites. Scale-up fermentation with Glomerella cinguiata, a fungal strain, has resulted in the isolation of a more polar metabolite (2).

• Ocean and Polar Research
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• 제24권1호
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• pp.47-53
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• 2002

To evaluate the effect of reed population on the distribution and activities of microorganisms, vertical distribution of heterotrophic bacteria, degradation rate of cellulose, extracellular aminopeptidase activity (APA) and metabolic diversity based on GN2 Microlog plate were measured at two salt marsh stations in Hogok-ri, Namyang Bay, west coast of Korea. The number of heterotrophic bacteria at station 1 (reed population inhabited area) showed 2 to 6 times higher than that of station 2 (exposed area) with exception in the surface layer. Cellulose degradation rates in station 1 showed more than 50%. month-I and higher than that of station 2 (10.2 to 38.4%. $month^{-1}$). Yet the APA at two stations did not show difference except surface layer and suggested that APA might not be a significant factor in degrading marsh plant debris. Lipid class compounds, cell wall polymers and L-alanine were widely used by microorganisms. The number and activities of bacterial populations especially concerned in plant debris degradation seemed to be stimulated by the reed communities.

• 한국미생물·생명공학회지
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• 제40권4호
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• pp.333-338
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• 2012

지의류는 곰팡이, 조류 및 남조균류의 공생체이다. 본 연구팀은 최근 북극 지의류로부터 분리한 몇몇 미생물 종의 항산화 활성에 대하여 연구하였고, 그들의 높은 항산화 활성을 확인하였다. 본 연구에서는 Cladonia sp., Sterocaulon sp., Umbilicaria sp. 및 Cetraria sp. 총 4종류의 지의류로부터 5종의 미생물을 새롭게 분리하였고 배양 후, 다양한 용매 추출법으로 그들의 항산화능을 조사하였다. DPPH와 ABTS 자유 라디컬 소거능 측정법 및 FRAP 분석 등을 수행하였다. 또한 총 폴리페놀함량과 총플라보노이드 함량 분석 역시 수행하였다. 지의류 유래 미생물 배양 추출액 중, Burkholderia sordidicola S5-B(T) 유사 미생물 종의 에틸아세테이트 추출액은 DPPH 분석에서 대조군인 아스코르빈산 (51.3%)에 비해 72.9%로 높은 항산화 활성을 보였을 뿐만 아니라, 높은 플라보노이드와 폴리페놀 함량을 나타내었다. 결과적으로, 이러한 지의류 유래 미생물 종들은 잠재적으로 천연 항산화제의 원천소재로서 이용가능할 것이다.

• Journal of Microbiology and Biotechnology
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• 제20권4호
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• pp.809-816
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• 2010

Microbial biotransformations can be used to predict mammalian drug metabolism. The present investigation deals with microbial biotransformation of valdecoxib using microbial cultures. Thirty-nine bacterial, fungal, and yeast cultures were used to elucidate the biotransformation pathway of valdecoxib. A number of microorganisms metabolized valdecoxib to various levels to yield nine metabolites, which were identified by HPLC-DAD and LC-MS-MS analyses. HPLC analysis of biotransformed products indicated that a majority of the metabolites are more polar than the substrate valdecoxib. Basing on LC-MS-MS analysis, the major metabolite was identified as a hydroxymethyl metabolite of valdecoxib, whereas the remaining metabolites were produced by carboxylation, demethylation, ring hydroxylation, N-acetylation, or a combination of these reactions. The hydroxymethyl and carboxylic acid metabolites were known to be produced in metabolism by mammals. From the results, it can be concluded that microbial cultures, particularly fungi, can be used to predict mammalian drug metabolism.

• 미생물학회지
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• 제41권3호
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• pp.157-163
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• 2005

요각류 Paracyclopina nana Acetate Kinase를 클로닝하였다. 전체 open reading frame은 1,200 bp이었으며, poly(A) signal sequence가 ORF에 내재되어 있었다. 분자계통학적 분석결과 P. nana acetate kinase 유전자는 진핵생물계 곰팡이류인 Aspegillus와 같은 branch를 형성하였고, P. nana acetate kinase가 다른 원핵미생물들의 acetate kinase와는 구별되며 fungi와 같은 branch에 존재하는 것을 확인하였다. 또한, E. coli를 이용하여 원핵세포 발현벡터를 이용한 단백질 발현 유도를 통하여 P. nana acetate kinase 단백질 분자량이 약 50 kDa에 이르는 것을 확인하였다. 이 자료는 본 요각류와 다른 생물의 acetate kinase 단백질의 생화학적 특성비교에 유용하게 쓰이리라 사료된다.

• Ocean and Polar Research
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• 제27권2호
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• pp.205-214
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• 2005

From ancient Antarctic glacier ice, we extracted total genomic DNA that was suitable for prokaryotic 16S rDNA gene cloning and sequencing, and bacterial artificial chromosome (BAC) library and end-sequencing. The ice samples were from the Dry Valley region. Age dating by $^{40}Ar/^{39}Ar$ analysis on the volcanic ashes deposited in situ indicated the ice samples are minimum 100,000-300,000 yr (sample DLE) and 8 million years (sample EME) old. Further assay proved the ice survived freeze-thaw cycles or other re-working processes. EME, which was from a small lobe of the basal Taylor glacier, is the oldest known ice on Earth. Microorganisms, preserved frozen in glacier ice and isolated from the rest of the world over a geological time scale, can provide valuable data or insight for the diversity, distribution, survival strategy, and evolutionary relationships to the extant relatives. From the 16S gene cloning study, we detected no PCR amplicons with Archaea-specific primers, however we found many phylotypes belonging to Bacteria divisions, such as Actinobacteria, Acidobacteria, Proteobacteria $({\alpha},\;{\beta},\;and\;{\gamma})$, Firmicutes, and Cytophaga-Flavobacterium-Bacteroid$. BAC cloning and sequencing revealed protein codings highly identical to phenylacetic acid degradation protein paaA, chromosome segregation ATPases, or cold shock protein B of present day bacteria. Throughput sequencing of the BAC clones is underway. Viable and culturable cells were recovered from the DLE sample, and characterized by their 16S rDNA sequences. Further investigation on the survivorship and functional genes from the past should help unveil the evolution of life on Earth, or elsewhere, if any.