• 한국미생물·생명공학회지
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• 제50권2호
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• pp.193-201
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• 2022

Methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-susceptible S. aureus (MSSA) are major causes of hospital- and community-acquired infections. The treatment of biofilm-related infections caused by these bacteria is a global healthcare challenge. Therefore, the development of alternative therapeutics is required. An essential oil extracted from Curcuma zedoaria (CZ) Rosc, also known as white turmeric, has been reported to possess various antimicrobial activities. In the present study, we evaluated the antibiofilm activities of an ethanolic extract of the CZ rhizome against MRSA and MSSA. The results showed that the CZ extract with the highest sub-minimum inhibitory concentration (sub-MIC), 1/2 MIC (0.312 mg/ml), significantly inhibited biofilm production by up to 80-90% in both tested strains. Subsequently, we evaluated the ability of the CZ extract to prevent cell-surface attachment to a 96-well plate and extracellular DNA (eDNA) release from the biofilm. The CZ extract demonstrated an inhibitory effect on bacterial attachment and eDNA release from the biofilm biomass. The CZ extract may inhibit biofilm formation by preventing eDNA release and cell-surface attachment. Therefore, this CZ extract is a potential candidate for the development of alternative treatments for biofilm-associated MRSA and MSSA infections.

• Journal of Microbiology and Biotechnology
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• 제33권1호
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• pp.15-27
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• 2023

The incidence of melioidosis cases caused by the gram-negative pathogen Burkholderia pseudomallei (BP) is seeing an increasing trend that has spread beyond its previously known endemic regions. Biofilms produced by BP have been associated with antimicrobial therapy limitation and relapse melioidosis, thus making it urgently necessary to understand the mechanisms of biofilm formation and their role in BP biology. Microbial cells aggregate and enclose within a self-produced matrix of extracellular polymeric substances (EPSs) to form biofilm. The transition mechanism of bacterial cells from planktonic state to initiate biofilm formation, which involves the formation of surface attachment microcolonies and the maturation of the biofilm matrix, is a dynamic and complex process. Despite the emerging findings on the biofilm formation process, systemic knowledge on the molecular mechanisms of biofilm formation in BP remains fractured. This review provides insights into the signaling systems, matrix composition, and the biosynthesis regulation of EPSs (exopolysaccharide, eDNA and proteins) that facilitate the formation of biofilms in order to present an overview of our current knowledge and the questions that remain regarding BP biofilms.

• Biotechnology and Bioprocess Engineering:BBE
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• 제3권1호
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• pp.6-10
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• 1998

A plasmid vector containing two reporter genes, mer-lux and lac-GFP, was transformed to both Escherichia coli and Pseudomonas putida. Their cellular activities and biofilm characteristics were investigated in flow-cell units by measuring bioluminescent lights and fluorescent levels of GFP. Bioluminescence was effective to monitor temporal cell activities, whereas fluorescent level of GFP was useful to indicate the overall cell activities during biofilm development. The light production rates of E. coli and P. putida cultures were dependent upon concentrations of HgCl2. Mercury molecules entrapped in P. putida biofilms were hardly washed out in comparison with those in E. coli biofilms, indicating that P. putida biofilms may have higher affinity to mercury molecules than E. coli biofilms. It was observed that P. putida expressed GFP cDNA in biofilms but not in liquid cultures. This may indicate that the genetic mechanisms of P. putida were favorably altered in biofilm conditions to make a foreign gene expression possible.

• Journal of Microbiology
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• 제45권6호
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• pp.558-565
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• 2007

Using microarray analysis, we determined those Salmonella genes induced at the entry of stationary phase, and subsequently discovered that uncharacterized yliH was induced most dramatically. We set out to establish the molecular mechanism underlying the stationary phase induction of yliH under the standard culture condition, LB with vigorous aeration, by analyzing its promoter activity in various mutant backgrounds, lacking stationary phase ${\sigma}$, $RpoS^-$, or stringent signal molecules ppGpp, ${\Delta}relA$ ${\Delta}spoT$. It was found that the stationary phase induction of yliHp was partially dependent on rpoS but entirely dependent on ppGpp. DNA sequence analysis revealed that the Salmonella yliH gene is composed of 381 base-pair nucleotides, with overall amino acid sequence revealing 76.38% amino acid identity and 88.98% similarity with Escherichia coli yliH, although no motif from data base was noted for its possible role. Recently however, it has been reported that yliH in E. coli was implicated in biofilm formation and motility by repressing these activities (Domka et al., 2006). We have constructed a mutant Salmonella deleting yliH gene by allele replacement and examined its phenotype, and found that the yliH in Salmonella more or less affects motility and adherence by enhancing these activities. The effect on biofilm formation in Salmonella was uncertain. Moreover, addition of cloned yliH of E. coli into Salmonella did not reduce motility or adherence. Taken together, it appears that the pathways implicating yliH for biofilm formation and motility in E. coli and in Salmonella are somewhat different.

• 생태와환경
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• 제56권3호
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• pp.250-258
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• 2023

담수해파리는 담수에서만 발견되는 해파리로써 다양성은 낮지만 전 세계적으로 보고 되고있다. 하지만 이들의 생태 및 발생 원인에 대해서는 정확하게 밝혀진 바가 없다. 따라서 모니터링을 통해 유생에서 폴립(polyp)단계를 통해 성장하는 담수해파리의 분포를 파악하는 것은 이들의 생태를 이해하는 데 중요하다. 본 연구는 미호강 수계 생물막(biofilm)의 환경유전자(eDNA)를 이용하여 담수해파리의 COI 유전자를 탐색하고 환경유전자를 이용한 담수해파리 탐색 가능성을 확인하고자 하였다. 미호강 수계 내 12개 지점 중 8개 지점에서 담수해파리 유전자가 확인되었으며, 대부분 상류에 저수지가 위치한 특성을 보였다. 이들 유전자는 대표적인 담수해파리로 알려진 소워비꽃모자해파리(Craspedacusta sowerbii)의 유전자로 확인되었으며 미호강 조사 지점에서 발견된 C. sowerbii는 이탈리아에서 발견된 종과 같은 계통이었다. 결과적으로 생물막의 환경유전자를 이용한 담수해파리 유전자 탐색방법은 담수해파리 출현 가능성이 높은 지역을 선택적으로 빠르게 선별(screening)할 수 있으며 이는 국내 담수해파리의 분포와 발생기작을 이해하는 데 중요한 단서를 제공할 수 있을 것으로 판단된다.

• Journal of Veterinary Science
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• 제25권2호
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• pp.30.1-30.16
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• 2024

Background: Biofilms, such as those from Staphylococcus epidermidis, are generally insensitive to traditional antimicrobial agents, making it difficult to inhibit their formation. Although quercetin has excellent antibiofilm effects, its clinical applications are limited by the lack of sustained and targeted release at the site of S. epidermidis infection. Objectives: Polyethylene glycol-quercetin nanoparticles (PQ-NPs)-loaded gelatin-N,O-carboxymethyl chitosan (N,O-CMCS) composite nanogels were prepared and assessed for the on-demand release potential for reducing S. epidermidis biofilm formation. Methods: The formation mechanism, physicochemical characterization, and antibiofilm activity of PQ-nanogels against S. epidermidis were studied. Results: Physicochemical characterization confirmed that PQ-nanogels had been prepared by the electrostatic interactions between gelatin and N,O-CMCS with sodium tripolyphosphate. The PQ-nanogels exhibited obvious pH and gelatinase-responsive to achieve on-demand release in the micro-environment (pH 5.5 and gelatinase) of S. epidermidis. In addition, PQ-nanogels had excellent antibiofilm activity, and the potential antibiofilm mechanism may enhance its antibiofilm activity by reducing its relative biofilm formation, surface hydrophobicity, exopolysaccharides production, and eDNA production. Conclusions: This study will guide the development of the dual responsiveness (pH and gelatinase) of nanogels to achieve on-demand release for reducing S. epidermidis biofilm formation.

• 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.

• Ocean and Polar Research
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• 제27권2호
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• pp.215-219
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• 2005

We isolated and identified three protease-producing bacteria that had inhabited the region around the Korean Arctic Research Station Dasan located at Ny-Alesund, Svalbard, Norway $(79^{\circ}N,\;12^{\circ}E)$. Biofilms were collected from the surface of a floating pier and from dead brown algae in a tide pool near the seashore. The biofilm samples were transported to the Korea Polar Research Institute (KOPRI) under frozen conditions, diluted in sterilized seawater, and cultured on Zobell agar plates with 1% skim milk at $10^{\circ}C$. Three clear zone forming colonies were selected as protease-producing bacteria. Phylogenetic analysis based on 16S rDNA sequences showed that these three stains shared high sequence similarities with Pseudoalteromonas elyakovii, Exiguobacterium oxidotofewm Pseudomonas jessenii, respectively. We expect these Arctic bacteria may be used to develop new varieties of protease that are active at low temperatures.

• Restorative Dentistry and Endodontics
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• 제47권1호
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• pp.11.1-11.11
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• 2022

This study aimed to describe the outcomes of the GentleWave system (GW) (Sonendo) on root canal treatment. Published articles were collected from scientific databases (MEDLINE/PubMed platform, Web of Science, Scopus, Science Direct and Embase). A total of 24 studies were collected from August/2014 to July/2021, 20 in vitro and 4 clinical. GW System was not associated with extrusion of the irrigant, promoted faster organic dissolution than conventional syringe irrigation (CSI), passive ultrasonic irrigation (PUI) continuous ultrasonic irrigation (CUI) and EndoVac, reduced more bacterial DNA and biofilm than PUI and CUI, promoted higher penetration of sodium hypochlorite into dentinal tubules than PUI and CUI in vitro, and removed more intracanal medication than CSI and PUI. GW was able to remove pulp tissue and calcifications. Moreover, its ability to remove hard-tissue debris and smear layer was better than that of CSI, and its ability to remove root canal obturation residues was lower or similar to that of PUI, and similar to that of CSI and EndoVac. Regarding root canal obturation of minimally instrumented molar canals, GW was associated with high-quality obturation. Clinically, the success rate of endodontic treatment using GW was 97.3%, and the short-term postoperative pain in the GW group was not different from CSI. Further research, mainly clinical, is needed to establish whether GW has any advantages over other available irrigation methods.

• 생명과학회지
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• 제22권5호
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• pp.605-612
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• 2012

포자형성균은 사람과 동물용의 프로바이오틱 제제로서 사용되어져 왔다. 포자형성균의 낮은 pH에 대한 안정성과 위내 생육저해 환경에 생존능은 프로바이오틱 제제로서 매력적이다. 본 연구는, 한국 전통 대두 발효 식품의 종균인 BCNU 9028균주를 메주로부터 분리하였다. 생리학적, 생화학적 특성과 16S 리보좀 DNA 염기서열 분석 결과 BCNU 9028균주는 $Bacillus$에 속하는 것을 확인하였다. $Bacillus$ sp. BCNU 9028은 pH 2.5에서 92%의 생존률을 보였으며, 0.3% 담즙산에서도 저항성을 나타냈다. 그리고, 식품 병원성균과의 응집정도와 자가결합능에 의해 $Bacillus$ sp. BCNU 9028는 $Listeria$ $monocytogenes$, $S.$ $aureus$ 및 $E.$ $coli$와 같은 식품 병원성균의 생물막형성과 부착을 저해할 수 있는 것을 확인하였다. BCNU 9028의 소수성 특성(63.3%)은 장관내 부착능이 우수할 것으로 나타났다. 특히, $Bacillus$ sp. BCNU 9028 균주는 그람양성 및 그람음성 병원성균 모두에 항균력을 갖는 것을 확인하였다. 이상의 결과로 $Bacillus$ sp. BCNU 9028균주가 프로바이오틱스로서 이용가능성이 있음을 제시하였다.