• Journal of Microbiology and Biotechnology
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• 제25권11호
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• pp.1871-1879
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• 2015

The complex roles of flagella in the pathogenesis of Campylobacter jejuni, a major cause of worldwide foodborne diarrheal disease, are important. Compared with the wild-type, an insertional mutation of the flgA gene (cj0769c) demonstrated significant decrease in the biofilm formation of C. jejuni NCTC11168 on major food contact surfaces, such as polystyrene, stainless steel, and borosilicate glass. The flgA mutant was completely devoid of flagella and non-motile whereas the wild-type displayed the full-length flagella and motility. In addition, the biofilm formation of the wild-type was inversely dependent on the viscosity of the media. These results support that flagellar-mediated motility plays a significant role in the biofilm formation of C. jejuni NCTC11168. Moreover, our adhesion assay suggests that it plays an important role during biofilm maturation after initial attachment. Furthermore, C. jejuni NCTC11168 wild-type formed biofilm with a net-like structure of extracellular fiber-like material, but such a structure was significantly reduced in the biofilm of the flgA mutant. It supports that the extracellular fiber-like material may play a significant role in the biofilm formation of C. jejuni. This study demonstrated that flgA is essential for flagellar biosynthesis and motility, and plays a significant role in the biofilm formation of C. jejuni NCTC11168.

• Journal of Microbiology and Biotechnology
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• 제18권8호
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• pp.1459-1469
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• 2008

Using a rotating biological contactor modified with a sequencing bath reactor system (SBRBC) designed and operated to remove phosphate and nitrogen [58], the microbial community structure of the biofilm from the SBRBC system was characterized based on the extracellular polymeric substance (EPS) constituents, electron microscopy, and molecular techniques. Protein and carbohydrate were identified as the major EPS constituents at three different biofilm thicknesses, where the amount of EPS and bacterial cell number were highest in the initial thickness of 0-100${\mu}m$. However, the percent of carbohydrate in the total amount of EPS decreased by about 11.23%, whereas the percent of protein increased by about 11.15% as the biofilm grew. Thus, an abundant quantity of EPS and cell mass, as well as a specific quality of EPS were apparently needed to attach to the substratum in the first step of the biofilm growth. A FISH analysis revealed that the dominant phylogenetic group was $\beta$- and $\gamma$-Proteobacteria, where a significant subclass of Proteobacteria for removing phosphate and/or nitrate was found within a biofilm thickness of 0-250${\mu}m$. In addition, 16S rDNA clone libraries revealed that Klebsiella sp. and Citrobacter sp. were most dominant within the initial biofilm thickness of 0-250${\mu}m$, whereas sulfur-oxidizing bacteria, such as Beggiatoa sp. and Thiothrix sp., were detected in a biofilm thickness over 250${\mu}m$. The results of the bacterial community structure analysis using molecular techniques agreed with the results of the morphological structure based on scanning electron microscopy. Therefore, the overall results indicated that coliform bacteria participated in the nitrate and phosphorus removal when using the SBRBC system. Moreover, the structure of the biofilm was also found to be related to the EPS constituents, as well as the nitrogen and phosphate removal efficiency. Consequently, since this is the first identification of the bacterial community and structure of the biofilm from an RBC simultaneously removing nitrogen and phosphate from domestic wastewater, and it is hoped that the present results may provide a foundation for understanding nitrate and phosphate removal by an RBC system.

• 한국미생물·생명공학회지
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• 제35권1호
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• pp.73-80
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• 2007

생물막 매개체를 도자기 격막으로 구획된 오수처리 반응기에 장착하고 직류 2volt의 전압을 부과하여 생물막 매개체가 산화 전위를 유지할 수 있게 유도하였다. 반면 대조실험을 위해 사용한 반응조의 생물막 매개체에는 전압을 부과하지 않았다 ABM-반응기와 CBM-반응기에서 배양시간에 따른 생물막의 구조, 생물량의 변화, 오수처리 효율 등을 측정하여 상호 차이를 비교하였다. 전자현미경으로 관찰한 ABM의 생물막은 CBM의 생물막에 비해 분산성이 크고 미생물이 과밀하게 성장하지 않았으나 CBM의 생물막은 배양 시간에 비례하여 지속적으로 성장하면서 생물막 매개체를 완전히 덮어 과밀 생물막을 형성하였다. ABM의 ORP는 CBM의 ORP 100 mV에 비해 매우 큰 차이를 보이는 800 mV를 유지하였으며, 반응액의 ORP 또한 ABM과 CBM의 영향을 받아 각각 550 mV와 400 mV를 유지하였다. ABM-반응기에서 오수처리 효율은 CBM-반응기에서 오수처리 효율의 약 2배 정도의 차이를 나타내었다. 이러한 결과로부터 생물막 매개체에 부과한 양전위의 전기 에너지는 생물막을 구성하는 미생물 과밀현상을 억제하고 매개체의 ORP를 높게 유지함으로서 미생물의 대사 활성을 촉진하고 결과적으로 오수내 함유된 유기물의 산화효율을 증가시키는 작용이 있는 것으로 확인되었다.

• Journal of Microbiology and Biotechnology
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• 제26권12호
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• pp.2116-2126
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• 2016

Bacterial biofilms are spatially structured communities that contain bacterial cells with a wide range of physiological states. The spatial distribution and speciation of copper in unsaturated Pseudomonas putida CZ1 biofilms that accumulated 147.0 mg copper per g dry weight were determined by transmission electron microscopy coupled with energy dispersive X-ray analysis, and micro-X-ray fluorescence microscopy coupled with micro-X-ray absorption near edge structure (micro-XANES) analysis. It was found that copper was mainly precipitated in a $75{\mu}m$ thick layer as copper phosphate in the middle of the biofilm, while there were two living cell layers in the air-biofilm and biofilm-medium interfaces, respectively, distinguished from the copper precipitation layer by two interfaces. The X-ray absorption fine structure analysis of biofilm revealed that species resembling $Cu_3(PO_4)_2$ predominated in biofilm, followed by Cu-Citrate- and Cu-Glutathione-like species. Further analysis by micro-XANES revealed that 94.4% of copper were $Cu_3(PO_4)_2$-like species in the layer next to the air interface, whereas the copper species of the layer next to the medium interface were composed by 75.4% $Cu_3(PO_4)_2$, 10.9% Cu-Citrate-like species, and 11.2% Cu-Glutathione-like species. Thereby, it was suggested that copper was initially acquired by cells in the biofilm-air interface as a citrate complex, and then transported out and bound by out membranes of cells, released from the copper-bound membranes, and finally precipitated with phosphate in the extracellular matrix of the biofilm. These results revealed a clear spatial pattern of copper precipitation in unsaturated biofilm, which was responsible for the high copper tolerance and accumulation of the biofilm.

• 상하수도학회지
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• 제18권2호
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• pp.181-187
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• 2004

The purpose of this study is to investigate the biofilm reactors capable of doing high efficiency treatment. Vertical fluidized bed biofilm reactor(VFBBR) and spiral fluidized bed biofilm reactor(SFBBR) was used for their performence in biodegradation of artificial sewage. The factors influencing the efficiency of those reactors were compared with difference of physical condition. They had same size but different structure to gain access of its unique characteristics. When recycle solution with flow rate of 22 mL/min and artificial sewage with flow rate of 2~10 mL/min were fed into two reactors in aerobic state, the average $COD_{cr}$, removal rate for biodegradation of SFBBR was greater than VFBBR. After reactor feed sewage was constantly maintained as flow rate of 4 mL/min and the recycle solution were changed to 10~32 mL/min respectively, the average $COD_{cr}$ removal rate of artificial sewage in SFBBR was greater than VFBBR. In this experiment for addition of support media into two reactors SFBBR was 4.1% excellent than VFBBR. Above all, SFBBR excelled VFBBR in boidegradation of organic matter in sewage.

• 한국환경보건학회지
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• 제37권2호
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• pp.124-132
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• 2011

Biofilm and aeration tank of pilot and full RABC (rotating activated Bacillus contactor) plant were analyzed to characterize and determine bacterial community structure in food wastewater treatment system at winter. Concentration of heterotrophic bacteria and Bacillus group was $10^7$ and $10^5$ CFU/ml, respectively, at biofilm of pilot-plant while others represented $10^6$ and $10^4$ CFU/ml, respectively. Five and eight phyla were detected at biofilm of pilot- and full-plant, respectively, by 16S rDNA sequencing. Biofilm of pilot-plant was dominated by ${\beta}$-Proteobacteria (38.8%), ${\gamma}$-Proteobacteria (22.4%), and Bacteroidetes (12.2%), and the most dominant genus was Zoogloeae genus (22.4%). Candidate division TM7 (12.5%) was only detected at biofilm of full-plant and it was dominated by Bacteroidetes (33.3%), ${\gamma}$-Proteobacteria (29.2%), and ${\beta}$-Proteobacteria (20.8%). Clostridium genus specific primer set enabled to detect the sequences of Clostridium genus. These suggested that anaerobic and aerobic bacteria were coexisted even from the initial period of biofilm formation and ${\beta}$-Proteobacteria, ${\gamma}$-Proteobacteria and Bacteroidetes were major phyla in biofilm of food wastewater treatment system at winter.

• 상하수도학회지
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• 제36권2호
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• pp.97-106
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• 2022

Recently microplastic (MP) biofilm is being attracted as an important environmental issue because it can act as a pollutant carrier in aqueous system. Therefore, this study investigated the MP biofilm communities originated from freshwater. The results showed the bacterial community structure of MP biofilm was distinctively different from the freshwater regardless of biofilm-forming condition and MP type. For MP biofilm communities exposed to raw freshwater, Solimonas variicoloris-like microbe, Frigidibacter albus-like microbe, Nitrospirillum amazonense-like microbe, and Pseudochroococcus couteii-like microbe became abundant, while Acinetobacter johnsonii, Macellibacteroides fermentans, and Sedimentibacter acidaminivorans-like microbe were found as major bacteria for MP biofilm communities exposed to organic rich condition. The results of this study suggest that the unique freshwater biofilm community could be formed on the MP surface.

• 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.

• Journal of Microbiology and Biotechnology
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• 제16권3호
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• pp.399-407
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• 2006

In this study, an electrical conductive carbon fiber was used as a biofilter matrix to electrochemically improve the biofilter function. A bioreactor system was composed of carbon fiber (anode), titanium ring, porcelain ring, inorganic nutrient reservoir, and VOC reservoir. Electric DC power of 1.5 volt was charged to the carbon fiber anode (CFA) to induce the electrochemical oxidation potential on the biofilter matrix, but not to the carbon fiber (CF). We tested the effects of electrochemical oxidation potential charged to the CFA on the biofilm structure, the bacterial growth, and the activity for metabolic oxidation of VOCs to $CO_2$, According to the SEM image, the biofilm structure developed in the CFA appeared to be greatly different from that in the CF. The bacterial growth, VOCs degradation, and metabolic oxidation of VOCs to $CO_2$ in the CFA were more activated than those in the CF. On the basis of these results, we propose that the biofilm structure can be improved, and the bacterial growth and the bacterial oxidation activity of VOCs can be activated by the electrochemical oxidation potential charged to a biofilter matrix.

• 상하수도학회지
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• 제20권5호
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• pp.685-690
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• 2006

The differences in microbial community structures between planktonic microorganism and biofilm in rivers were investigated using respiratory quinone profiles. The compositions of microbial quinone for 4 tributaries of the Kyongan Stream located in/flowing through Yongin City, Gyeonggi-Do were analyzed. Ubiquinone(UQ)-8, UQ-9, menaquinone(MK)-6 and Plastoquinone(PQ)-9 were observed in all samples of planktonic microorganism and biofilm for the sites investigated, Most planktonic microorganism and biofilm had UQ-8(15 to 30%) and PQ-9(over 30%) as the dominant quinone type. These results indicated that oxygenic phototrophic microbes(cyanobacteria and/or eukaryotic phytoplankton) and UQ-8 containing proteobacteria constituted major microbial populations in the river. The quinone concentration in the river waters tested, which reflects the concentration of planktonic microorganisms, increases with increasing DOC. Further research into this is required. The microbial diversities of planktonic microorganism and biofilm calculated based on the composition of all quinones were in the range from 4.2 to 7.5, which was lower than those for activated sludge(ranging from 11 to 14.8) and soils(ranging from 13.4 to 16.8). The use of quinone profile appears to be a useful tool for the analysis of microbial community structure in river.