• 한국미생물학회:학술대회논문집
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• 한국미생물학회 2005년도 International Meeting of the Microbiological Society of Korea
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• pp.182.4-182
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• 2005

• 한국미생물생명공학회:학술대회논문집
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• 한국미생물생명공학회 2003년도 2003 Annual Meeting, BioExhibition and International Symposium
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• pp.161-163
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• 2003

• Environmental Engineering Research
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• 제15권3호
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• pp.141-147
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• 2010

The objective of this study was to assess the biofouling characteristics of the Bacillus biofilm formed on reverse osmosis (RO) membranes. For the study, a sporogenic Bacillus sp. was isolated from the seawater intake to a RO process, with two distinct sets of experiments performed to grow the Bacillus biofilm on the RO membrane using a lab-scale crossflow membrane test unit. Two operational feds were used, 9 L sterile-filtered seawater and 109 Bacillus cells, with flow rates of 1 L/min, and a constant 800 psi-pressure and pH 7.6. From the results, the membrane with more fouling, in which the observed permeate flux decreased to 33% of its initial value, showed about 10 and 100 times greater extracellular polymeric substances and spoOA genes expressions, respectively, than the those of the less fouled membrane (flux declined to 20% of its initial value). Interestingly; however, the number of culturable Bacillus sp. in the more fouled membrane was about 10 times less than that of the less fouled membrane. This indicated that while the number of Bacillus had less relevance with respect to the extent of biofouling, the activation of the genes of interest, which is initiative of biofilm development, had a more positive effect on biofouling than the mass of an individual Bacillus bacterium.

• 대한환경공학회지
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• 제22권5호
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• pp.971-980
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• 2000

가용성 메탄산화효소를 분비하는 혼합 메탄자화균총을 celite R-635에 고정화시켜 TCE 분해를 위한 새로운 형식의 가압 산기식 혼합 메탄자화균총 고정층 생물막 반응기를 설계하였다. Celite R-635에서 용출되는 용액의 pH는 약 4시간 후부터 안정화되어서 중성 영역에 도달하므로 더 이상 중화할 필요가 없었다. 혼합 메탄자화균 생물막을 완전히 형성하기 위해서는 130일이 걸렸으며, 처음에 흰색을 띠고 있었던 celite는 점차 붉게 변해 갔었다. 생물막이 형성된 후에는 메탄과 산소를 각각 2.5~4, 8~10 ppm씩 공급할 때 하루 동안 체류한 후 0.5~1, 1~2 ppm 정도로 농도가 낮아졌다. 초기에 2 ppm의 TCE를 메탄자화균 고정층 생물막 반응기에서 10시간 동안 체류시켰을 때 79.9%의 분해 효율을 보였다.

• 대한기계학회논문집B
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• 제36권11호
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• pp.1119-1126
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• 2012

세균의 집단 행동은 생물막의 형성에 중요한 역할을 하고 있다. 본 연구에서는 대장균(E. coli) 및 고초균(B. subtilis) 군집에서 형성된 유동성 생물막의 유체역학적 특성을 비교하고자 초기에 아가 플레이트 내에서 층을 이루다가 성장하는 군집 표면 위로 자발적으로 분포되는 200 nm의 형광입자를 가시화 하였다. 대장균 군집에서는 유동하지 않는 200 nm 크기의 형광입자를 이용하여 성장하는 세균 군집의 3차원 형상 프로파일을 측정하였다. 고초균 군집의 경계에서 나타나는 와류 패턴은 고초균이 분비하는 계면활성제 내에서 유동하는 형광입자를 추적하여 가시화하였다. 본 연구는 세균의 생리 기능을 조절하는 새로운 물리적인 요소를 밝혀내고 세균의 증식 및 군집 이동에 영향을 미치는 유동성 생물막의 효과를 파악하는 첫걸음이 될 것이다.

• Journal of Microbiology and Biotechnology
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• 제28권3호
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• pp.482-490
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• 2018

Candida albicans infections are often problematic to treat owing to antifungal resistance, as such infections are mostly associated with biofilms. The ability of C. albicans to switch from a budding yeast to filamentous hyphae and to adhere to host cells or various surfaces supports biofilm formation. Previously, the ethanol extract from Paeonia lactiflora was reported to inhibit cell wall synthesis and cause depolarization and permeabilization of the cell membrane in C. albicans. In this study, the P. lactiflora extract was found to significantly reduce the initial stage of C. albicans biofilms from 12 clinical isolates by 38.4%. Thus, to assess the action mechanism, the effect of the P. lactiflora extract on the adhesion of C. albicans cells to polystyrene and germ tube formation was investigated using a microscopic analysis. The density of the adherent cells was diminished following incubation with the P. lactiflora extract in an acidic medium. Additionally, the P. lactiflora-treated C. albicans cells were mostly composed of less virulent pseudohyphae, and ruptured debris was found in the serum-containing medium. A quantitative real-time PCR analysis indicated that P. lactiflora downregulated the expression of C. albicans hypha-specific genes: ALS3 by 65% (p = 0.004), ECE1 by 34.9% (p = 0.001), HWP1 by 29.2% (p = 0.002), and SAP1 by 37.5% (p = 0.001), matching the microscopic analysis of the P. lactiflora action on biofilm formation. Therefore, the current findings demonstrate that the P. lactiflora ethanol extract is effective in inhibiting C. albicans biofilms in vitro, suggesting its therapeutic potential for the treatment of biofilm-associated infections.

• Journal of Microbiology and Biotechnology
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• 제15권5호
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• pp.952-964
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• 2005

The diesel-degrading activities of biofilms sampled from petroleum-contaminated groundwaters in urban subway drainage systems were examined in liquid cultures, and the microbial populations of the biofilms were characterized by denaturing gel gradient electrophoresis (DGGE) and 16S rDNA sequence analysis. Biofilm samples derived from two sites (19 K and 20 K) at subway Station N and Station I could degrade around $80\%$ of applied diesel within 20 and 40 days, respectively, at $15^{\circ}C$, and these results were strongly correlated with the growth patterns of the biofilms. The closest phylogenetic neighbor of a dominant component in the 19 K biofilm was Thiothrix fructosivorans strain Q ($100\%$ similarity). Four dominant strains in the 20 K biofilm were closely related to Thiothrix fructosivorans strain Q ($100\%$ similarity), Thiothrix sp. CC-5 ($100\%$ similarity), Sphaerotilus sp. IF14 ($99\%$ similarity), and Cytophaga-Flexibacter-Bacterioides (CFB) group bacterium RW262 ($98\%$ similarity). Three dominant members in the Station I biofilms were very similar to uncultured Cytophagales clone CRE-PA82 ($91\%$ similarity), Pseudomonas sp. WDL5 ($97\%$ similarity), and uncultured CFB group bacterium LCK-64 ($94\%$ similarity). The microbial components of the biofilms differed depending on the sampling site. This is the first report on the isolation of clones highly similar to Thiothrix fructosivorans and Thiothrix sp. from biofilms in petroleum-polluted groundwaters, and the first evidence that these organisms may play major roles in petroleum degradation and/or biofilm-development.

• 한국식품과학회지
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• 제25권3호
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• pp.210-213
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• 1993

본 실험의 목적은 공극률과 상향유속의 관계에서 세입자의 유동특성을 고찰하는 데 있다 Column 내경은 유동층의 유속과 공극률과의 관계에 큰 영향을 미치지 못했으며 유속과 공극률과의 관계는 다음과 같다. $\frac{u}{u_t}={\varepsilon}^{3.703}$----모래$\frac{u}{u_t}={\varepsilon}^{3.5665}$----이온 교환수지$\frac{u}{u_t}={\varepsilon}^{4.066}$---GAC 또 유동층 매질입자는 구형을 사용하는 것이 일정유속에서 공극률을 낮게 유지할 수 있어 좋았고 실제로 미생물막 유동층 반응기에서는 미생물막이 매질에 부착되면 비중이 감소하므로 매질의 비중이 높을수록 유동층을 유지하기가 쉽다.

• 한국미생물·생명공학회지
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• 제13권3호
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• pp.273-278
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• 1985

새로운 페니실린 발효방법으로서, Penicillin chrysogenum의 포자를 담체의 미세구멍 조직에 흡착시킨 후 배양하여 얻은 균사증식담체를 이용하여 페니실린 발효를 시도하였다. 고정화 담체로써는 Celite가 가장 효율적이었으며, 이때 균사는 담체의 내부에서부터 포자가 발아하여 담체의 표면에서 증식하기 때문에 매우 안정된 biofilm growth를 얻을 수 있었다. 프라스크 배양에서 담체의 양을 5-10% 첨가하였을 때 세포의 증식과 페니실린의 생산이 전통적인 dispersed filamentous growth 에 의한 발효방법보다 현저히 증가되었다. 그러나 두 경우 모두 세포의 활성은 1900 unit/mg-cellㆍhr로 일정하였다. 균사증식 담체를 이용하여 유동층 발효조에서 반연속식으로 발효를 진행시킨 결과 페니실린의 연속생산이 가능함을 발견하였다. 그러나 발효조내에서 biofilm growth시 film두께의 조절과 페니실린 생산성을 일정수준으로 오랫동안 유지시킬 수 있는 방법이 앞으로 연구되어야 할 것으로 판단되었다.

• Journal of Microbiology and Biotechnology
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• 제31권1호
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• pp.130-136
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• 2021

Persister cell formation and biofilms of pathogens are extensively involved in the development of chronic infectious diseases. Eradicating persister cells is challenging, owing to their tolerance to conventional antibiotics, which cannot kill cells in a metabolically dormant state. A high frequency of persisters in biofilms makes inactivating biofilm cells more difficult, because the biofilm matrix inhibits antibiotic penetration. Fatty acids may be promising candidates as antipersister or antibiofilm agents, because some fatty acids exhibit antimicrobial effects. We previously reported that fatty acid ethyl esters effectively inhibit Escherichia coli persister formation by regulating an antitoxin. In this study, we screened a fatty acid library consisting of 65 different fatty acid molecules for altered persister formation. We found that undecanoic acid, lauric acid, and N-tridecanoic acid inhibited E. coli BW25113 persister cell formation by 25-, 58-, and 44-fold, respectively. Similarly, these fatty acids repressed persisters of enterohemorrhagic E. coli EDL933. These fatty acids were all medium-chain saturated forms. Furthermore, the fatty acids repressed Enterohemorrhagic E. coli (EHEC) biofilm formation (for example, by 8-fold for lauric acid) without having antimicrobial activity. This study demonstrates that medium-chain saturated fatty acids can serve as antipersister and antibiofilm agents that may be applied to treat bacterial infections.