• 한국산학기술학회논문지
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• 제18권1호
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• pp.141-147
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• 2017

본 연구에서는 클로닝과 생어 염기서열 분석으로 획득된 16S rRNA 유전자 염기서열을 메타분석하여 반려견 분변 박테리아를 조사하였다. 이러한 메타분석을 위해서 RDP 데이터베이스(Release 11, Update 3)에 등록되어 있는 반려견 분변 박테리아 유래 16S rRNA 유전자 염기서열 검색하여 획득하였다. RDP 데이터베이스에서 총 420개의 반려견 분변 박테리아 유래 16S rRNA 유전자 염기서열이 확인되었고, 그 중에서 42개 유전자 염기서열이 배양가능한 박테리아에서 유래한 것으로 확인되었다. 이러한 420개의 유전자 염기서열은 박테리아 분류학상의 '문'(phylum)에서 총 5개(Firmicutes, Bacteroidetes, Actinobacteria, Fusobacteria, Proteobacteria)로 분류되었다. 그 중에서 Firmicutes가 가장 우점하는 '문'이었고, 총 420개 유전자 중에서 55.2%를 차지하였다. Bacteroidetes는 32.1%로 두 번째로 우점하는 '문'이였고, 다음으로 Actinobacteria(6.4%), Fusobacteria(3.8%), Proteobacteria(2.4%)가 우점하였다. 박테리아 분류학상의 '속'(genus)에서는 Bacteroidetes의 하위 단계인 Bacteroides가 가장 우점하였고 총 420개 유전자 중에서 30.0%를 차지하였다. 반면에 Firmicutes의 하위 단계인 Clostridium XI는 두 번째로 우점하는 '속'으로 총 420개 유전자 중에서 27.4%를 차지하였다. 추정상의 '종'(species)인 Operational taxonomic units의 수는 82개로 확인되었다. 본 연구의 결과는 반려견 분변 내 미생물 다양성을 이해하는데 도움을 줄 수 있을 것이고, 향후 반려견의 건강과 웰빙에 관한 연구에 활용될 수 있을 것이다.

• 자원환경지질
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• 제57권3호
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• pp.305-317
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• 2024

토양 내 미생물 군집의 변화가 비소 용출에 미치는 영향을 파악하기 위해 비소 오염 토양(F1, G7, G10)을 대상으로 실험을 수행하였다. 실험은 혐기적 조건에서 비소 오염 토양을 ① BAC: 멸균토양 + Bacillus fungorum, ② IND: 토착균 토양, ③ MIX: 토착균 토양 + B. fungorum으로 나누어 혐기적 조건에서 유산염을 탄소원으로 하여 7주간 배양하였다. 실험 결과, 토착균 군집이 존재하는 IND와 MIX에서 BAC에 비하여 높은 함량의 비소가 용출되었으며, pH가 높은 G10 토양에서 F1과 G7 토양에 비해 비소 용출량이 월등히 높았다. G10 토양의 경우, 다른 토양과 달리 용출된 비소 중 As(III) 함량의 비율이 낮았다. 이러한 결과는 토양에 따라 상이하게 나타나는 미생물 군집의 차이에 기인할 수도 있다. IND와 MIX는 7주차에 이르러 미생물의 다양성이 크게 감소하였으며 실험 조건에 적응한 Eubacteriales 및 Bacillales 등의 우점목이 번성하였다. F1 토양의 7주차 MIX에서는 Bacteroidales, G7 토양의 7주차 IND와 MIX에서는 Rummelibaciilus가 번성하였다. G10 토양의 IND와 MIX에서는 Enterobacterales가 우점목 중 하나를 차지하였다. 현재로서는 미생물 군집의 변화가 비소의 지구화학적 거동에 어떠한 메커니즘으로 영향을 미치는지에 관한 정보가 부족하나, 이러한 결과는 토양 내 마이크로바이옴이 비소의 용출을 조절하는 요인 중 하나로 기능할 수 있음을 나타낸다.

• BMB Reports
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• 제42권9호
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• pp.586-592
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• 2009

The bactenecin is an antibacterial peptide with an intramolecular disulfide bond. We recently found that homodimeric bactenecin exhibits more potent antibacterial activity than the monomeric form and retains its activity at physiological conditions. Here we assess the difference in the modes of antibiotic action of homodimeric and monomeric bactenecins. Both monomeric and dimeric bactenecins almost completely killed both Staphylococcus aureus and E. coli within 10-30 min at concentrations of $8-16\;{\mu}M$. However, exposure to liposomes elicited an increase in the fluorescence quantum yield from a tryptophan-containing monomeric analog, while the homodimeric analog showed a significant reduction in fluorescence intensity. Moreover, unlike the monomer, the homodimer displayed apparent membrane-lytic activity enabling release of various sized dyes from liposomes, and rapidly and fully depolarized the S. aureus membrane. Together, our results suggest that homodimeric bactenecin forms pores in the bacterial membrane, while monomeric one penetrates through the membrane to target intracellular molecules/organelles.

• The Plant Pathology Journal
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• 제34권1호
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• pp.44-58
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• 2018

Pseudomonas chlororaphis 30-84 is a biological control agent selected for its ability to suppress diseases caused by fungal pathogens. P. chlororaphis 30-84 produces three phenazines: phenazine-1-carboxylic acid (PCA), 2-hydroxy-phenazine-1-carboxylic acid (2OHPCA) and a small amount of 2-hydroxy-phenazine (2OHPHZ), and these are required for fungal pathogen inhibition and wheat rhizosphere competence. The two, 2-hydroxy derivatives are produced from PCA via the activity of a phenazine-modifying enzyme encoded by phzO. In addition to the seven biosynthetic genes responsible for the production of PCA, many other Pseudomonas strains possess one or more modifying genes, which encode enzymes that act independently or together to convert PCA into other phenazine derivatives. In order to understand the fitness effects of producing different phenazines, we constructed isogenic derivatives of P. chlororaphis 30-84 that differed only in the type of phenazines produced. Altering the type of phenazines produced by P. chlororaphis 30-84 enhanced the spectrum of fungal pathogens inhibited and altered the degree of take-all disease suppression. These strains also differed in their ability to promote extracellular DNA release, which may contribute to the observed differences in the amount of biofilm produced. All derivatives were equally important for survival over repeated plant/harvest cycles, indicating that the type of phenazines produced is less important for persistence in the wheat rhizosphere than whether or not cells produce phenazines. These findings provide a better understanding of the effects of different phenazines on functions important for biological control activity with implications for applications that rely on introduced or native phenazine producing populations.

• BMB Reports
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• 제48권1호
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• pp.36-41
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• 2015

Recently, we demonstrated that human serum amyloid P component (SAP) specifically recognizes exposed bacterial peptidoglycan (PGN) of wall teichoic acid (WTA)-deficient Staphylococcus aureus ${\Delta}$tagO mutant cells and then induces complement-independent phagocytosis. In our preliminary experiments, we found the existence of human serum immunoglobulins that recognize S. aureus PGN (anti-PGNIgGs), which may be involved in complement-dependent opsonophagocytosis against infected S. aureus cells. We assumed that purified serum anti-PGN-IgGs and S. aureus ${\Delta}$tagO mutant cells are good tools to study the molecular mechanism of anti-PGN-IgG-mediated phagocytosis. Therefore, we tried to identify the intracellular molecule(s) that is involved in the anti-PGN-IgG-mediated phagocytosis using purified human serum anti-PGN-IgGs and different S. aureus mutant cells. Here, we show that anti-PGN-IgG-mediated phagocytosis in phorbol myristate acetate-treated U937 cells is mediated by $Ca^{2+}$ release from intracellular $Ca^{2+}$ stores and anti-PGN-IgGdependent $Ca^{2+}$ mobilization is controlled via a phospholipase C${\gamma}$-2-mediated pathway.

• Journal of Pharmaceutical Investigation
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• 제22권3호spc1호
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• pp.35-47
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• 1992

Hydrogel coated ring shaped ocular inserts (containing the antibiotic, tylosin tartrate) were used in an evaluation of the effectiveness of polymeric ocular drug release devices for treating infectious bovine keratoconjunctivitis. The in vivo experiments represent the first experiments using hydrogel ocular inserts containing an antibiotic for treating infectious bovine keratoconjunctivitis. In the infection tests, ten calves. were challenged with $2.4{\times}10^8{\sim}1.6{\times}10^9$ Moraxella bovis (a bacterium) colonies per eye following two ten minute ultraviolet radiation eye preconditioning exposures. Ninety five percent of the eyes (19 of 20 eyes) were successfully infected by this method. All infected eyes were monitored for the presence of the bacteria quantitiatively, and clinical observations were made for 14 days. The test was performed by three consecutive steps: 1) inoculation with 2 ultraviolet (UV) radiations, 2) growth of bacterial colonies and 3) treatment with medicated ring-shaped devices. The first. bacteriological measurements after 2 UV exposures were performed at day 3 of the tests. At day 7 after inoculation of both eyes of a calf with M. bovis, a medicated or a non-medicated ring-shaped device was inserted into each eye of a calf. The eye receiving the non-medicated ring was taken as a control for comparison with the eye that received a medicated ring. During the next 7 day period following a medicated ring insertion, the number of bacteria in the treated eyes dropped dramatically to negligible levels (0 to 30 colony forming units/swab), while the control eyes which received a non-medicated ring still exhibited a relatively high number of bacteria ($10^3\;to\;10^6$ colony forming units/swab). The number of bacteria was significantly reduced by the antibiotic released from the medicated ocular insert.

• Journal of Microbiology and Biotechnology
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• 제11권2호
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• pp.259-265
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• 2001

Staphylococal infection still remains to be one of the most serious infections, having various complications in the clinical use of indwelling polymeric medical devices. However, there are a few promising systems showing a high antibacterial effect without causing any demage of polymer backbone under biological environments such as blood or body fluid. In order to resolve this problem, we have designed a new antibiotic releasing system via a hydrolysis mechanism. The surface of biomedical polyurethane (PU) was modified by using 1,6-diisocyanatohexane (HMDI) to immobilize the rifampicon. Also, the immobilized rifampicin was designed to be released by a selective cleavage of the unstable carbamate linkage that exists on the rifampicin-immobilized polyurethane (PHR). The immobilization of rifampicin on the surface of polyurethane was confirmed by the disappearance of the characteristics IR absorbance peak of the isocyanate (-NCO) group at $2,267\;cm^{-1}$. The PHR showed a continuous rifampicin release profile under an aqueous environment of 10 mM of PBS (phosphate-buffered saline) for ove 6 days. The rifampicin molecules, which are released from PHR under an optimal bacterial infection environment, had a higher antibacterial activity against both S. aureus and S. epidermidis than rifampicin-incorporated polyurethane (RIP). In addition, the PHR maintained a stable antibacterial effect under a blood-mimic aqueous environment such as bovine calf serum.

• 농업과학연구
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• 제46권4호
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• pp.981-989
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• 2019

Coffee is a popular beverage worldwide, and the scale of consumption is growing rapidly. Many studies have shown that increased coffee consumption has various effects on human health, including beneficial effects on liver diseases, clinical type 2 diabetes, and Parkinson's disease. However, the influences of coffee or caffeine (a component of coffee) on the gut microbiota have not been examined in detail. Here, we tested whether caffeine could alter the antimicrobial activity of L. casei against E. coli. Interestingly, we found that treatment with 0.3 mg/mL caffeine increased the antimicrobial activity of L. casei against E. coli. This activity was not associated with the release of lactic acid but did appear to be related to a heat-labile factor present in the L. casei culture supernatant. Our analyses suggest that the putative antimicrobial factor found in the culture supernatant of L. casei treated with caffeine may be bacteriocin. Taken together, our results suggest that caffeine, which is an ingredient of coffee, increases the antimicrobial activity of L. casei against E. coli through the enhanced production of bacteriocin. These findings also suggest that coffee consumption affects the ability of beneficial bacteria to decrease pathogenic bacteria and/or prevent the progression of bacterial infection-associated diseases in the gut.

• Molecules and Cells
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• 제43권4호
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• pp.350-359
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• 2020

Pathogenic aminoacyl-tRNA synthetases (ARSs) are attractive targets for anti-infective agents because their catalytic active sites are different from those of human ARSs. Mupirocin is a topical antibiotic that specifically inhibits bacterial isoleucyl-tRNA synthetase (IleRS), resulting in a block to protein synthesis. Previous studies on Thermus thermophilus IleRS indicated that mupirocin-resistance of eukaryotic IleRS is primarily due to differences in two amino acids, His581 and Leu583, in the active site. However, without a eukaryotic IleRS structure, the structural basis for mupirocin-resistance of eukaryotic IleRS remains elusive. Herein, we determined the crystal structure of Candida albicans IleRS complexed with Ile-AMP at 2.9 A resolution. The largest difference between eukaryotic and prokaryotic IleRS enzymes is closure of the active site pocket by Phe55 in the HIGH loop; Arg410 in the CP core loop; and the second Lys in the KMSKR loop. The Ile-AMP product is lodged in a closed active site, which may restrict its release and thereby enhance catalytic efficiency. The compact active site also prevents the optimal positioning of the 9-hydroxynonanoic acid of mupirocin and plays a critical role in resistance of eukaryotic IleRS to anti-infective agents.

• Membrane and Water Treatment
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• 제9권3호
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• pp.181-188
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• 2018

A sidestream contains the filtrate or concentrate from the belt filter press, filter backwash and supernatant from sludge digesters. The sidestream flow, which heads back into the sewage treatment train, is about 1-3% less than the influent flow. However, the sidestream can increase the nutrient load since it contains high concentrations of phosphorus and nitrogen. In this study, the removal of PO4-P with organic matter characteristics and bacteriological changes during the sidestream treatment via ladle furnace (LF) slag was investigated. The sidestream used in this study consisted of 11-14% PO4-P and 3.2-3.6% soluble chemical oxygen demand in influent loading rates. LF slag, which had a relatively high $Ca^{2+}$ release compared to other slags, was used to remove $PO_4-P$ from the sidestream. The phosphate removal rates increased as the slag particle size decreased 19.1% (2.0-4.0 mm, 25.2% (1.0-2.0 mm) and 79.9% (0.5-1.0 mm). The removal rates of dissolved organic carbon, soluble chemical oxygen demand, color and aromatic organic matter ($UV_{254}$) were 17.6, 41.7, 90.2 and 77.3%, respectively. Fluorescence excitation-emission matrices and liquid chromatography-organic carbon detection demonstrated that the sidestream treatment via LF slag was effective in the removal of biopolymers. However, the removal of dissolved organic matter was not significant during the treatment. The intact bacterial biomass decreased from $1.64{\times}10^8cells/mL$ to $1.05{\times}10^8cells/mL$. The use of LF slag was effective for the removal of phosphate and the removal efficiency of phosphate was greater than 80% for up to 100 bed volumes.