• 미생물학회지
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• 제50권2호
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• pp.108-113
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• 2014

녹농균(Pseudomonas aeruginosa)과 비브리오 불니피쿠스균(Vibrio vulnificus)은 그람 음성의 병원균들로써, quorum sensing(QS) 기전을 통해 병원성을 발현하는 세균들이다. 이들 병원균의 감염은 많은 경우 생물막 형성에 의해 매개된다고 알려져 있는데, 이에 본 연구에서는 P. aeruginosa와 V. vulnificus를 대상으로 QS 기전의 유무에 따른 생물막 형성의 시간적 추이를 분석해 보았다. 그 결과 P. aeruginosa의 경우 QS 기전이 결핍된 균주가 야생형에 비해 초기 부착은 더 잘 하였으나, 이후 생물막 구조의 성숙 능력은 야생형에 비해 현저히 떨어짐을 알 수 있었다. 이러한 특성 때문에 야생형과 QS 결핍 균주의 생물막 형성을 시간의 추이에 따라 정량적으로 비교해 보면 초기 10시간 정도 까지는 QS 결핍 균주가 더 많은 생물막을 형성하다가, 이후 야생형이 더 많이 생물막을 형성하는 역전 현상이 관찰되었다. V. vulnificus는 P. aeruginosa와는 달리 QS 결핍 균주가 야생형보다 더 많은 생물막을 형성한다고 보고된 균주이다. 이 균주에서 같은 방식으로 생물막 형성을 조사해 본 결과, 108시간의 장시간 동안에도 항상 QS 결핍 균주가 야생형 보다 더 많은 생물막을 형성하여, 역전 현상은 관찰되지 않았다. 이 결과는 P. aeruginosa의 경우에는 QS 기전이 초기 부착은 저해하는 방향으로, 성숙과정은 촉진시키는 방향으로 작용하며, V. vulnificus에서는 일관되게 생물막 형성을 저해하는 방향으로 작용함을 보여주는 것이다. 따라서 생물막 제어를 위한 타겟으로 QS기전을 이용할 때에는 제어하고자 하는 생물막 형성 단계와 세균 종을 함께 고려하여야 한다고 제안한다.

• Journal of Microbiology and Biotechnology
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• 제15권6호
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• pp.1221-1228
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• 2005

Carbon electrode was applied to a wastewater treatment system as biofilm media. The spatial distribution of heterotrophic bacteria in aerobic wastewater biofilm grown on carbon electrode was investigated by scanning electron microscopy, atomic force microscopy, and biomass measurement. Five volts of electric oxidation and reduction potential were charged to the carbon anode and cathode of the bioelectrochemical system, respectively, but were not charged to electrodes of a conventional system. To correlate the biofilm architecture of bacterial populations with their activity, the bacterial treatment efficiency of organic carbons was measured in the bioelectrochemical system and compared with that in the conventional system. In the SEM image, the biofilm on the anodic medium of the bioelectrochemical system looked intact and active; however, that on the carbon medium of the conventional system appeared to be shrinking or damaging. In the AFM image, the thickness of biofilm formed on the carbon medium was about two times of those on the anodic medium. The bacterial treatment efficiency of organic carbons in the bioelectrochemical system was about 1.5 times higher than that in the conventional system. Some denitrifying bacteria can metabolically oxidize $H_{2}$, coupled to reduction of $NO_{3}^{-}\;to\;N_{2}$. $H_{2}$ was produced from the cathode in the bioelectrochemical system by electrolysis of water but was not so in the conventional system. The denitrification efficiency was less than $22\%$ in the conventional system and more than $77\%$ in the bioelectrochemical system. From these results, we found that the electrochemical coupling reactions between aerobic and anaerobic reactors may be a useful tool for improvement of wastewater treatment and denitrification efficiency, without special manipulations such as bacterial growth condition control, C/N ratio (the ratio of carbon to nitrogen) control, MLSS returning, or biofilm refreshing.

• Journal of Microbiology and Biotechnology
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• 제23권12호
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• pp.1673-1682
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• 2013

Citrobacter sp. is a cause of significant opportunistic nosocomial infection and is frequently found in human and animal feces, soil, and sewage water, and even in industrial waste or putrefaction. Biofilm formation is an important virulence trait of Citrobacter sp. pathogens but the process and characteristics of this formation are unclear. Therefore, we employed in vitro assays to study the nutritional and environmental parameters that might influence biofilm formation of C. werkmanii BF-6 using 96-well microtiter plates. In addition, we detected the relative transcript levels of biofilm formation genes by RT-PCR. Our results indicated that the capacity of C. werkmanii BF-6 to form biofilms was affected by culture temperature, media, time, pH, and the osmotic agents glucose, sucrose, NaCl, and KCl. Confocal laser scanning microscopy results illustrated that the structure of biofilms and extracellular polysaccharide was influenced by 100 mM NaCl or 100 mM KCl. In addition, nine biofilm formation genes (bsmA, bssR, bssS, csgD, csgE, csgF, mrkA, mrkB, and mrkE) were found to contribute to planktonic and biofilm growth. Our data suggest that biofilm formation by C. werkmanii BF-6 is affected by nutritional and environmental factors, which could pave the way to the prevention and elimination of biofilm formation using proper strategies.

• Journal of Animal Science and Technology
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• 제59권2호
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• pp.4.1-4.5
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• 2017

Background: Biofilms were the third-dimensional structure in the solid surface of bacteria. Bacterial biofilms were difficult to control by host defenses and antibiotic therapies. Escherichia coli (E. coli) and Salmonella were popular pathogenic bacteria that live in human and animal intestines. Essential oils are aromatic oily liquids from plant materials and well known for their antibacterial activities. Method: This study was conducted to determine effect of essential oil on anti-biological biofilm formation of E. coli and Salmonella strains in in vitro experiment. Two kinds of bacterial strains were separated from 0.2 g pig feces. Bacterial strains were distributed in 24 plates per treatment and each plates as a replication. The sample was coated with a Bacterial biofilm formation was. Result: Photographic result, Escherichia coli (E. coli) and Salmonella bacteria colony surface were thick smooth surface in control. However, colony surface in blended and single essential oil treatment has shown crack surface layer compared with colony surfaces in control. Conclusion: In conclusion, this study could confirm that essential oils have some interesting effect on anti-biofilm formation of E. coli and Salmonella strains from pig feces.

• 한국미생물·생명공학회지
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• 제33권1호
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• pp.1-8
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• 2005

Since Anton van Leeuwen­hoek first observed a surface-associated multicellular structure of bacterial cells in the 17th century, it has been shown to exhibit an ability to form a biofilm by numerous bacterial species. The biofilm formation is composed of distinct developmental stages, which include an attachment/adhesion of a single cell, a proliferation toward monolayered coverage, a propagation to aggregated microcolony, a maturation to 3-dimensional structure, and subsequently a local degradation. Investigation to identify the essential factors for bacterial biofilm formation has been performed via classical genetic approaches as well as recently developed technologies. The initial stage requires bacterial motility provided by a flagellum, and outermembrane components for surface signal interaction. Type IV-pilus and autoaggregation factors, e.g., type I-fimbriae or Ag43, are necessary to reach the stages of monolayer and micro colony. The mature biofilm is equipped with extracellular polymeric matrix and internal water-filled channels. This complex architecture can be achieved by differential expressions of several hundred genes, among which the most studied are the genes encoding exopolysaccharide biosyntheses and quorum-sensing regulatory components. The status of our knowledge for the biofilms found in humans and natural ecosystems is discussed in this minireview.

• 미생물학회지
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• 제52권1호
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• pp.49-58
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• 2016

부유 세균의 군집과 구별되는 생물막내 세균 군집은 다양한 수생태계에서 중요한 생태학적 역할을 수행한다. 자연계에서 생물막이 생태학적으로 중요함에도 불구하고, 남극 해양 환경에서 생물막 형성 과정 동안의 세균 군집 구조와 그들의 변화에 대한 연구는 수행되지 않았다. 본 연구에서, 남극 해양 환경에서 생물막 형성 초기 단계에서의 세균 군집 구조 변화를 16S rRNA 유전자의 pyrosequencing을 통해 수행하였다. 생물막내 전반적인 세균 군집은 주변의 해수의 군집과 매우 달랐다. 전체 세균 군집의 78.8%에서 88.3%를 차지한 Gammaproteobacteria와 Bacteroidetes의 상대적 풍부도는 생물막의 형성에 따라 급격하게 변하였다. Gammaproteobacteria는 생물막 형성 진행에 따라 증가하다가 (4일째에 75.7%), 7일째에 46.1%로 감소하였다. 반면, Bacteroidetes는 초기에서 중기로 갈수록 감소하다가 다시 증가하는 양상을 보이며, Gammaproteobacteria와 반대의 변화 양상을 나타내었다. 생물막 형성의 초기 과정에 우점 하는 OTU (>1%)들의 변화 양상은 시기에 따라 뚜렷한 차이를 보였다. Gammaproteobacteria에 속하는 종의 경우, 4일째까지 증가한 반면, 첫째날 가장 우점 하였던 문인 Bacteroidetes에 속하는 종은 4일째까지 감소한 후, 다시 증가하는 양상을 보였다. 흥미롭게, Pseudoalteromonas prydzensis가 67.4%를 차지하며 우점 하였는데, 이는 생물막 형성에 이 종이 중요한 역할을 수행함을 시사하는 것으로 보인다.

• The Journal of Advanced Prosthodontics
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• 제5권2호
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• pp.140-146
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• 2013

PURPOSE. The aim of this study was to investigate the destructive effects of biofilm formation and/or biocorrosive activity of 6 different oral microorganisms. MATERIALS AND METHODS. Three different heat polymerized acrylic resins (Ivocap Plus, Lucitone 550, QC 20) were used to prepare three different types of samples. Type "A" samples with "V" type notch was used to measure the fracture strength, "B" type to evaluate the surfaces with scanning electron microscopy and "C" type for quantitative biofilm assay. Development and calculation of biofilm covered surfaces on denture base materials were accomplished by SEM and quantitative biofilm assay. According to normality assumptions ANOVA or Kruskal-Wallis was selected for statistical analysis (${\alpha}$=0.05). RESULTS. Significant differences were obtained among the adhesion potential of 6 different microorganisms and there were significant differences among their adhesion onto 3 different denture base materials. Compared to the control groups after contamination with the microorganisms, the three point bending test values of denture base materials decreased significantly (P<.05); microorganisms diffused at least 52% of the denture base surface. The highest median quantitative biofilm value within all the denture base materials was obtained with P. aeruginosa on Lucitone 550. The type of denture base material did not alter the diffusion potential of the microorganisms significantly (P>.05). CONCLUSION. All the tested microorganisms had destructive effect over the structure and composition of the denture base materials.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2001년도 추계학술발표대회
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• pp.282-285
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• 2001

질산화 생물여과 시스템 내 생물막 안에 존재하는 ammonia oxidizers 및 nitrite oxidizers의 군집 구조 및 공간적 분포를 조사하였다. FISH 분석 결과 생물막 내 숫적으로 우점종을 이루는 미생물은 ammonia oxidizer인 Nitrosomonas spp.로 나타났으며 nitrite oxidizer 인 Nilrospira spp.에 비해 3 ${\sim}$ 5 정도 더 많이 존재하였다. 이는 실협 기간동안 완전한 질산화를 보였지만 반응기가 2 년 이상 nitrite 축적을 위해 높은 free ammonia 농도 빛 낮은 용존 산소 상태에서 운선되어 nitrite oxidizers에 저해를 주었기 때문인 것으로 사료된다. FISH와 결합된 CLSM 관찰 결과 생물막 전체에 걸쳐 ammonia oxidizer가 분포하는 반면 안쪽으로 갈수록 nitrite oxidizers가 분포함을 보였다. 이는 폐수의 ammonium 을 생물막 내 ammon ia oxidizer가 먼저 nitrite로 산화시키고 이를 nitrite oxidizers가 곧바로 nitrate로 산화시키기 때문이다.

• Journal of Microbiology and Biotechnology
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• 제15권5호
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• pp.938-945
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• 2005

For elucidating excessive growth of biofilm that subsequently leads to the clogging problem in a small town's sewer lines of Wisconsin, the FISH method was employed. At the beginning of the simulated experiments, ${\beta}$-subclass proteobacteria prevailed in runs fed with industrial wastewater, while ${\gamma}$-subclass proteobacteria dominated in runs with domestic wastewater. However, the bacterial community structure changed significantly over six weeks; Cytophaga-Flavobacterium (CF)­group bacteria dominated in most runs fed with the small town's wastewater regardless of their source, while CF-group decreased strongly in run fed with domestic sewage from another city (Madison). It was also microscopically confirmed that most of those clogging materials was toilet tissue, which in turn may lead to vigorous growth of cellulose-degrading CF-group bacteria. This dominant presence of CF-group bacteria in the small town's sewer indicates that the main constituent of biofilm, toilet tissue (cellulose) in sewage, might have induced the unique pattern of their microbial community structure. Therefore, it suggests that molecular technique is useful for monitoring the clogging problems in sewer lines.

• Journal of Microbiology and Biotechnology
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• 제26권2호
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• pp.373-384
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• 2016

The membrane-aerated biofilm reactor (MABR) is a promising municipal wastewater treatment process. In this study, two cross-flow MABRs were constructed to explore the carbon and nitrogen removal performance and bacterial succession, along with changes of influent loading shock comprising flow velocity, COD, and NH₄-N concentrations. Redundancy analysis revealed that the function of high flow velocity was mainly embodied in facilitating contaminants diffusion and biosorption rather than the success of overall bacterial populations (p > 0.05). In contrast, the influent NH₄-N concentration contributed most to the variance of reactor efficiency and community structure (p < 0.05). Pyrosequencing results showed that Anaerolineae, and Beta- and Alphaproteobacteria were the dominant groups in biofilms for COD and NH₄-N removal. Among the identified genera, Nitrosomonas and Nitrospira were the main nitrifiers, and Hyphomicrobium, Hydrogenophaga, and Rhodobacter were the key denitrifiers. Meanwhile, principal component analysis indicated that bacterial shift in MABR was probably the combination of stochastic and deterministic processes.