• Bulletin of the Korean Chemical Society
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• 제32권10호
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• pp.3726-3729
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• 2011

Biofilm formation is inevitable in a bioelectrochemical system in which microorganisms act as a sole biocatalyst. Cathodic biofilm (CBF) works as a double-edged sword in the performance of the air-cathode microbial fuel cells (MFCs). Proton and oxygen crossover through the CBF are limited by the robust structure of extracellular polymeric substances, composition of available constituents and environmental condition from which the biofilm is formed. The MFC performance in terms of power, current and coulombic efficiency is influenced by the nature and origin of CBF. Development of CBF from different ecological environment while keeping the same anode inoculums, contributes additional charge transfer resistance to the total internal resistance, with increase in coulombic efficiency at the expense of power reduction. This study demonstrates that MFC operation conditions need to be optimized on the choice of initial inoculum medium that leads to the biofilm formation on the air cathode.

• Restorative Dentistry and Endodontics
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• 제44권1호
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• pp.7.1-7.10
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• 2019

Apical periodontitis is a biofilm-mediated infection. The biofilm protects bacteria from host defenses and increase their resistance to intracanal disinfecting protocols. Understanding the virulence of these endodontic microbiota within biofilm is essential for the development of novel therapeutic procedures for intracanal disinfection. Both the disruption of biofilms and the killing of their bacteria are necessary to effectively treat apical periodontitis. Accordingly, a review of endodontic biofilm types, antimicrobial resistance mechanisms, and current and future therapeutic procedures for endodontic biofilm is provided.

• Environmental Engineering Research
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• 제15권2호
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• pp.71-78
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• 2010

To understand the effects of acclimation schemes on the formation of anode biofilms, different electrical performances are characterized in this study, with the roles of suspended and attached bacteria in single-chamber microbial fuel cells (MFCs). The results show that the generation of current in single-chamber MFCs is significantly affected by the development of a biofilm matrix on the anode surface containing abundant immobilized microorganisms. The long-term operation with suspended microorganisms was demonstrated to form a dense biofilm matrix that was able to reduce the activation loss in MFCs. Also, a Pt-coated anode was not favorable for the initial or long-term bacterial attachment due to its high hydrophobicity (contact angle = $124^{\circ}$), which promotes easy detachment of the biofilm from the anode surface. Maximum power ($655.0\;mW/m^2$) was obtained at a current density of $3,358.8\;mA/m^2$ in the MFCs with longer acclimation periods. It was found that a dense biofilm was able to enhance the charge transfer rates due to the complex development of a biofilm matrix anchoring the electrochemically active microorganisms together on the anode surface. Among the major components of the extracellular polymeric substance, carbohydrates ($85.7\;mg/m^2_{anode}$) and proteins ($81.0\;mg/m^2_{anode}$) in the dense anode biofilm accounted for 17 and 19%, respectively, which are greater than those in the sparse anode biofilm.

• 미생물학회지
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• 제54권2호
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• pp.167-168
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• 2018

Staphylococcus xylosus는 일반적으로 포유동물의 피부에 존재하며 식품가공설비와 의료기기 등에서도 발견이 보고되었다. 본 연구에서는 강력한 생물막 생성 특성을 가지는 Staphylococcus xylosus S170의 전체 유전체 서열을 분석하여 보고한다. 이 유전체는 2,910,005 bp 크기, 2,674개의 단백질 코딩 서열과 22개의 rRNA, 57개의 tRNA유전자를 포함한다. 본 연구에서 제공하는 유전체 정보는 생물막 관련 유전자 분석으로 생물막 형성 기작을 좀 더 잘 이해하는데 도움이 될 수 있다.

• 치위생과학회지
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• 제19권3호
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• pp.162-169
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• 2019

Background: Oral diseases are caused by various systemic and local factors, the most closely related being the biofilm. However, the challenges involved in removing an established biofilm necessitate professional care for its removal. This study aimed to evaluate and compare the effects of professional self and professional biofilm care in healthy patients to prevent the development of periodontal diseases. Methods: Thirty-seven patients who visited the dental clinic between September 2018 and February 2019 were included in this study. Self-biofilm care was performed by routine tooth brushing and professional biofilm care was provided using the toothpick method (TPM) or the oral prophylaxis (OP) method using a rubber cup. Subgingival bacterial motility and halitosis (levels of hydrogen sulfide, $H_2S$; methyl mercaptan, $CH_3SH$; and di-methyl sulfide, $(CH_3)_2S$) were measured before, immediately after, and 5 hours after the preventive treatment in the three groups. Repeated measures analysis of variance test was performed to determine significant differences among the groups. Results: TPM was effective immediately after the prevention treatment, whereas OP was more effective after 5 hours (proximal surfaces, F=16.353, p<0.001; smooth surfaces, F=66.575, p<0.001). The three components responsible for halitosis were effectively reduced by professional biofilm care immediately after the preventive treatment; however, self-biofilm care was more effective after 5 hours ($H_2S$, F=3.564, p=0.011; $CH_3SH$, F=6.657, p<0.001; $(CH_3)_2S$, F=21.135, p<0.001). Conclusion: To prevent oral diseases, it is critical to monitor the biofilm. The dental hygienist should check the oral hygiene status and the ability of the patient to administer oral care. Professional biofilm care should be provided by assessing and treating each surface of the tooth. We hope to strengthen our professional in biofilm care through continuous clinical research.

• 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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• 제28권5호
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• pp.748-756
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• 2018

Biofilms are of vital significance in bioconversion and biotechnological processes. In this work, sugarcane molasses was used to enhance biofilms for the improvement of the production of fumigaclavine C (FC), a conidiation-associated ergot alkaloid with strong anti-inflammatory activities. Biofilm formation was more greatly induced by the addition of molasses than the addition of other reported biofilm inducers. With the optimal molasses concentration (400 g/l), the biofilm biomass was 6-fold higher than that with sucrose, and FC and conidia production was increased by 5.8- and 3.1-fold, respectively. Moreover, the global secondary metabolism regulatory gene laeA, FC biosynthetic gene fgaOx3, and asexual central regulatory genes brlA and wetA were upregulated in molasses-based biofilms, suggesting the upregulation of both asexual development and FC biosynthesis. This study provides novel insight into the stimulatory effects of molasses on biofilm formation and supports the widespread application of molasses as an inexpensive raw material and effective inducer for biofilm production.

• 동의생리병리학회지
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• 제26권1호
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• pp.74-80
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• 2012

Candida albicans is a common opportunistic pathogen and is frequently associated with biofilm formation occurring on the surfaces of host tissues and medical devices. On account of the distinct resistance of C. albicans biofilms to the conventional antifungal agents, new strategies are required to cope with these infections. The root of Polygonum cuspidatum has been used for medicinal purposes in East Asia. The aim of this study was to assess the anticandidal potential of the P. cuspidatum ethanol extract by evaluating biofilm formation, integrity of the cell membranes of C. albicans and adhesion of C. albicans cells to polystyrene surfaces. The growth and development of the biofilm was assessed using an XTT reduction assay, and the extract (0.39 mg/ml) significantly reduced ($41.1{\pm}17.8%$) biofilm formation of 11 C. albicans strains. The extract damaged the cell membranes of C. albicans and remarkably inhibited cell adhesion to polystyrene surfaces. The plant extract displayed fungistatic activity without significant hemolytic activity. Based on the results of this study, the P. cuspidatum extract has promising potential for use in treating biofilm-associated Candida infection.

• 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.

• 상하수도학회지
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• 제26권6호
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• pp.767-777
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• 2012

Annular Biofilm Reactor (ABR) equipped with coupons of three different pipe materials (STS 304, PVC, PE) was used to generate drinking water biofilm samples. The level of assimilable organic carbon (AOC) during the sample generation period was $37.3{\mu}g/L$, and this level did not seem to be low enough to limit the formation of biofilm in this study. Terminal-restriction fragment length polymorphism (T-RFLP) analyses determined T-RF profile as early as 3 h of exposure on PVC coupons. Average surface roughness ($R_a$) measured by atomic force microscopic analyses was 125.7 nm for PVC, and this value was higher than for STS (71.6 nm) and PE (74.0 nm). However, biofilm formation was faster on STS (6 h) than on PE (12 h), which indicated that surface roughness might not be the only factor that controlled the initiation of biofilm development. Upon detection of the T-RF peaks, richness (S) and diversity indices such as Shannon (H) and Simpson (1/D) demonstrated a rather slow increase until 48 h followed by rapid increase regardless of the pipe materials. Differences of microbial community structures among the biofilm samples were determined based on the cluster analysis using Jaccard coefficients (Sj). Biofilm communities could be divided into two distinct groups according to the exposure time regardless of the pipe materials. First group contained a young (< 48 h) biofilm samples (10 out of 11) but second group contained a mature (${\geq}$ 48 h) samples (11 out of 14). Results suggested that, due to the complexity of biofilm, the targeting of the first group of cluster was crucial for optimizing the management of drinking water distribution systems and controlling microbial growth.