• Journal of Microbiology and Biotechnology
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• v.24 no.10
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• pp.1327-1336
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• 2014

Bacillus amyloliquefaciens strain NJZJSB3 has shown antagonism of several phytopathogens in vitro, especially Sclerotinia sclerotiorum. Both the broth culture and cell suspension of strain NJZJSB3 could completely protect the detached leaves of canola (Brassica napus) from S. sclerotiorum infection. In pot experiments, the application of strain NJZJSB3 cell suspension ($10^8CFU/ml$) decreased the disease incidence by 83.3%, a result similar to commercially available fungicide (Dimetachlone). In order to investigate the potential biocontrol mechanisms of strain NJZJSB3, the nonvolatile antifungal compounds it produces were identified as iturin homologs using HPLC-ESI-MS. Antifungal volatile organic compounds were identified by gas chromatography-mass spectrometry. The detected volatiles toluene, phenol, and benzothiazole showed antifungal effects against S. sclerotiorum in chemical control experiments. Strain NJZJSB3 also produced biofilm, siderophores and cell-wall-degrading enzymes (protease and ${\beta}$-1,3-glucanase). These results suggest that strain NJZJSB3 can be a tremendous potential agent for the biological control of sclerotinia stem rot.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.09a
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• pp.75-78
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• 2001

Authors evaluated the feasibility of a permeable reactive biobarrier (PRB) treated with biofilm formed by Beijerinckia indica (B.indica). This study focused on evaluating two potentials of B.indica for the requirements of PRB: reducing the hydraulic conductivity and degrading the polycyclic aromatic hydrocarbons (PAHs). The hydraulic conductivity was estimated by rigid wall column test and finally the values were converted to the values of intrinsic permeability. The nutrient solution was passed through the biobarrier column to activate the bacterium and then leachate was in turn carried into the column to evaluate the durability of the biobarrier. Phenanthrene was selected as a representative substance of PAHs. The ability of degrading phenanthrene by B.indica was evaluated by two-phase partitioning bioreactor after estimating the possibility with two pretests: observing the colony formation and the optical density on glucose-free medium containing phenanthrene. With the results, B.indica produced large amount of strongly adhesive exopolysaccharides (EPS) and reduced several orders of magnitude of the hydraulic conductivity after 2 weeks of cultivation. Furthermore, about 1000mg/1 of phenanthrene could be degraded by B.indica in the two-phase partitioning bioreactor. In conclusion, the application of the bacterium, B.indica, was found to have a potential role of a PRB to retain and remove contaminants in porous media.

• Journal of Environmental Science International
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• v.16 no.1
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• pp.121-128
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• 2007

This study performed in order to evaluate the effects of pipe materials on corrosion and bacteria regrowth using a laboratory scale batch test. Two varieties of feed water with different microbial conditions were selected: tap water, surface river water (Han River water), and five pipe materials; carbon steel, copper, galvanized iron, stainless steel, and PVC, Carbon steel and galvanized iron pipes showed higher corrosion rates than other materials. In terms of attached bacterial growth, pipes with PVC and stainless steel showed higher bacteria concentration compared to other materials. Pseudomonas vesicularis was the predominant bacteria found on biofilm. The behavior of bacterial growth in the pipes was observed using a scanning electron microscope.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.520-523
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• 2000

Phenol and other phenolic compounds are common constituents of aqueous effluents from processes such as polymeric resin production, oil refining and cokeing plants. Phenol is a both toxic and lethal of fish at relatively low concentrations e.g. 5-25 mg/L and imparts objectionable tastes to drinking water at far lower concentration. Therefore, the treatment of phenol effluent is important. Among the various techniques of phenol wastewater treatment, microbial teratment is a popular process. The breakdown of phenols by microorganisms has recived considerable attention, because of its biochemical interest and its industrial importance in effluent treatment. This research was performed to investigate the dynamics of microbial community, biofilm growth and the comparison of phenol removal efficiency by RBC (Rotating Biological Contactor) using Rhodococcus sp. EL-GT The experiment was carried out at rotating speed of 10ppm and hydraulic retention time of 7 hours. As time passed, phenol removal efficiency was gained highly. The RBC using Rhodococcus sp. EL-GT completely degraded 15 mM.

• International Journal of Oral Biology
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• v.39 no.1
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• pp.41-47
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• 2014

Streptococcus mutans (S. mutans) is a facultative anaerobic bacterium mainly found in the oral cavity and is known to contribute to tooth decay and gingivitis. Recent studies on intestinal microbiota have revealed that microorganisms forming a biofilm play important roles in maintaining tissue homeostasis through their own metabolism. However, the physiological roles of oral microorganisms such as S. mutans are still unclear. In our current study, we identified that constituents released from S. mutans (CR) reduce arecoline-mediated cytotoxicity without producing toxic effects themselves. Arecoline, as a major alkaloid of areca nut, is known to mediate cytotoxicity on oral epithelial cells and induces a sustained intracellular $Ca^{2+}$ ($[Ca^{2+}]_i$) increase that is cytotoxic. The exposure of human gingival fibroblast (HGF) cells to CR not only inhibited the sustained $[Ca^{2+}]_i$ increase but also the initial $[Ca^{2+}]_i$ elevation. In contrast, CR had no effects on the gene regulation mediated by arecoline. These results demonstrate that S. mutans has physiological role in reducing cytotoxicity in HGF cells and may be considered a novel pharmaceutical candidate.

• KSBB Journal
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• v.27 no.3
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• pp.145-150
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• 2012

This study was accomplished using packed bed column reactors that contain nonsurface-modified polypropylene media and surface-modified media from hydrophobic surface property into hydrophilic property by ion beam irradiation. The objectives of this research was investigated the characteristics of organic compounds removal and microbe attachment from sewage of school cafeteria in these reactors. In 736.8 mg/L of the average inflow $COD_{Cr}$ concentration the reactors with and without surface modification showed 81.8% and 70.3% of average $COD_{Cr}$ removal efficiencies, respectively, which proves the $COD_{Cr}$ removal efficiency of surface-modified media reactor is higher than that of nonsurface-modified media reactor. After 90 days, there were maximum differences between modified system and non-modified system. In that time the maximum removal efficiency of $COD_{Cr}$ was 96.5% in modified system and was 85.2% in non-modified system that showed removal efficiency of surface-modified media system is 11.3% higher than that of nonsurface-modified media system. The average removal efficiency of SS was 80.4% for the surface modified system and 61.6% for the non-modified system under same condition. Also, the reactor of surface-modified media has advantage on microbe attachment and biofilm formation.

• Journal of Dairy Science and Biotechnology
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• v.31 no.2
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• pp.179-186
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• 2013

Pseudomonas spp. are Gram-negative psychrophilic bacteria, which can proliferate at refrigeration temperature. The bacteria produce heat-stable enzymes that can degrade fat and protein in foods. Hence, Pseudomonas spp. are related to the spoilage of milk, dairy products, and meat products under cold storage, causing economic loss. In the food industry, various methods have been used to remove bacteria including Pseudomonas spp. in food-related conditions, but they can be resistant to antimicrobials and sanitizers because they form biofilms regulated by quorum sensing (cell density-dependent cell-to-cell signaling). Since Pseudomonas cells in biofilms can cross-contaminate foods resulting in food spoilage and the survival of food-borne pathogens in food-related conditions, efficient decontamination technology and microbiological criteria should be established to reduce the occurrence of food spoilage by Pseudomonas spp.

• Journal of Korean Society of Water and Wastewater
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• v.25 no.3
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• pp.335-342
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• 2011

Secondary effluent contains particle compounds which are comprised of microorganisms that occurs membrane fouling when the water is reused. This study evaluates the characteristics of membrane fouling of secondary effluent reuse. Effects of chemical backwashing are analyzed to reduce membrane fouling by regular chemical backwashing. As the result, major membrane foulants are verified EPS materials which include protein and polysaccharide that cause biofilm cake layer on the membrane. Also, sodium hypochlorite is applied to chemical backwashing. The backwashing improves recover rate when injected chemical concentration is increased and chemical backwashing cycle is amplified. Chemical backwashing cycle affects more than injected chemical concentration yet idle time does not noticeably influence on reducing membrane fouling.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.4
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• pp.497-502
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• 2012

Anaerobic Digestion Process is evaluated as efficient wastewater treatment process with the removal of high concentrations of organic waste and production of biogas. This study was performed using hybrid anaerobic hybrid reactor (AHR) which consists of anaerobic sludge blanket (UASB) and biofilm-coated filter media was applied for Palm Oil Mill Effluent (POME) for 80 days to know optimum removal efficiency and production of biogas by comparing each part which divided changing Organic Loading Rate (OLR). As a result of this study, the removal efficiency was 90.4 % when the organic loading rate of influent was 15 kg COD/$m^3$/day. Since organic loading rate was up to 20 kg COD/$m^3$/day, the removal rate declined 80.7%. Over loading of influent caused sludge expansion and overproduction of microorganism. Amount of biogas was collected 82.3 L/day and pH was remained 6.9 constantly with balance of alkalinity.

• BMB Reports
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• v.44 no.1
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• pp.1-10
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• 2011

Inter-cellular communication via diffusible small molecules is a defining character not only of multicellular forms of life but also of single-celled organisms. A large number of bacterial genes are regulated by the change of chemical milieu mediated by the local population density of its own species or others. The cell density-dependent "autoinducer" molecules regulate the expression of those genes involved in genetic competence, biofilm formation and persistence, virulence, sporulation, bioluminescence, antibiotic production, and many others. Recent innovations in recombinant DNA technology and micro-/nano-fluidics systems render the genetic circuitry responsible for cell-to-cell communication feasible to and malleable via synthetic biological approaches. Here we review the current understanding of the molecular biology of bacterial intercellular communication and the novel experimental protocols and platforms used to investigate this phenomenon. A particular emphasis is given to the genetic regulatory circuits that provide the standard building blocks which constitute the syntax of the biochemical communication network. Thus, this review gives focus to the engineering principles necessary for rewiring bacterial chemo-communication for various applications, ranging from population-level gene expression control to the study of host-pathogen interactions.