• Journal of Microbiology and Biotechnology
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• v.16 no.6
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• pp.939-945
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• 2006

The physiological characteristics and function of the exopolysaccharide (EPS) produced by Lactobacillus rhamnosus ATCC 9595 were determined. The total quantity of EPS was rapidly increased to 496$\pm$20 mg/l during the exponential phase, and then maintained steadily during the stationary phase. During the exponential phase (18 h), the total EPS consisted of 61% cell-bound EPS (cb-EPS) and 39% released EPS (r-EPS), whereas the relative proportion of EPS during the stationary phase (48 h) was convered to 23% cb-EPS and 77% r-EPS. On gel permeation chromatography, cb-EPS was fractionated as a single peak of 8.6$\times10^6$ Da, whereas r-EPS was fractionated as two peaks with average molecular weights of 4.3$\times$10$^4$ and 8.6$\times10^6$ Da. Interestingly, both EPS species exhibited anticancer properties and cholera toxin-binding activities. Our results suggest that the EPS generated by L. rhamnosus ATCC 9595 might be suitable for use as a functional food or food supplement.

• Journal of Microbiology and Biotechnology
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• v.31 no.8
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• pp.1144-1153
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• 2021

A released exopolysaccharide (rEPS)-producing strain (LM187) with good acid resistance, bile salt resistance, and cholesterol-lowering properties was isolated from Sichuan paocai and identified as Leuconostoc mesenteroides subsp. mesenteroides. The purified rEPS, designated as rEPS414, had a uniform molecular weight of 7.757 × 10⁵ Da. Analysis of the monosaccharide composition revealed that the molecule was mainly composed of glucose. The Fourier transform-infrared spectrum showed that rEPS414 contained both α-type and β-type glycosidic bonds. ¹H and ¹³C nuclear magnetic resonance spectra analysis showed that the purified rEPS contained arabinose, galactose, and rhamnose, but less uronic acid. Scanning electron microscopy demonstrated that the exopolysaccharide displayed a large number of scattered, fluffy, porous cellular network flake structures. In addition, rEPS414 exhibited strong in vitro antioxidant activity. These results showed that strain LM187 and its rEPS are promising probiotics with broad prospects in industry.

• KSBB Journal
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• v.23 no.1
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• pp.18-22
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• 2008

Various probiotic Lactobacillus spp. are known to produce exopolysaccharide (EPS) which has potential health promoting functionality. A Lactobacillus paracasei strain producing EPS was isolated from healthy human. This strain, named L. paracasei KLB58, was grown on modified MRS medium. Experiments were conducted under various growth conditions to optimize the EPS production. Our study showed that incubation temperature played an important role in EPS production. When incubation temperature was changed from $37^{\circ}C$ to $25^{\circ}C$, the increase of EPS production (28.1 mg/ml) was the highest in our experiment. The type of carbon source in the medium also affected EPS production. Galactose was the most effective for EPS production among the carbon sources examined. Using galactose, glucose, lactose and sucrose, the amount of released EPS was 38.9 mg/ml, 35.6 mg/ml, 21.76 mg/ml and 16.9 mg/ml, respectively. However, acidity in growth medium inhibited EPS productivity due to the low growth yield. When grown at pH 4, L. paracasei KLB58 could only produce EPS of 14.6 mg/ml. When the initial amounts of nitrogen and carbon sources were examined, EPS production was not significantly affected by nitrogen source while carbon source affected considerably.

• Journal of Microbiology and Biotechnology
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• v.21 no.11
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• pp.1174-1178
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• 2011

Exopolysaccharides (EPSs) are microbial polysaccharides that are released outside of the bacterial cell wall. There have been few studies on EPS-producing lactic acid bacteria that can enhance macrophage activity and the underlying signaling mechanism for cytokine expression. In the current study, EPS-overproducing Lactobacillus (L.) paracasei KB28 was isolated from kimchi and cultivated in conditioned media containing glucose, sucrose, and lactose. The whole bacterial cells were obtained with their EPS being attached, and the cytokine-inducing activities of these cells were investigated. Gas chromatography analysis showed the presence of glucose, galactose, mannose, xylose, arabinose, and rhamnose in EPS composition. EPS-producing L. paracasei KB28 induced the expression of tumor necrosis factor (TNF)-${\alpha}$, interleukin (IL)-6, and IL-12 in mouse macrophages. This strain also caused the degradation of $I{\kappa}B{\alpha}$ and phosphorylation of the major MAPKs: Jun N-terminal kinase (JNK), p38, and extracellular signal-regulated kinase (ERK)1/2. The use of pharmacological inhibitors showed that different signaling pathways were involved in the induction of TNF-${\alpha}$, IL-6 and IL-12 by L. paracasei KB28. Our results provide information for a better understanding of the molecular mechanisms of the immunomodulatory effect of food-derived EPS-producing lactic acid bacteria.

• Journal of Applied Biological Chemistry
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• v.50 no.2
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• pp.41-45
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• 2007

Polaromonas naphthalenivorans CJ2, responsible for naphthalene degradation at a coal tar contaminated site, was isolated on MSB agar media supplied with naphthalene vapor as the sole carbon source at $10^{\circ}C$. The strain is not isolated under the same isolation condition using the same soil sediment at $20^{\circ}C$ although its optimum temperature is about $20^{\circ}C$. In this work we explored the reason why strain CJ2 could not have been isolated on MSB agar with naphthalene vapor at $20^{\circ}C$. Dispersed CJ2 cells in PBS buffer formed colonies on MSB agar with naphthalene vapor at $10^{\circ}C$ with low naphthalene vapor pressure, but not at $20^{\circ}C$ with high naphthalene vapor pressure. However, streaked cells without resuspension grew on MSB agar with naphthalene vapor at $10^{\circ}C,\;20^{\circ}C$, and even $25^{\circ}C$. Investigation of scanning electron microscopy showed that CJ2 cells formed extracellular polysaccharide (EPS) capsules, which were released easily from CJ2 cells by just dispersion. Therefore, it is concluded that strain CJ2 is able to overcome the naphthalene toxicity by forming a capsule-type barrier around the cells although it is susceptible to naphthalene toxicity at high temperature.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.3
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• pp.248-255
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• 2010

This study was carried out to assess the feasibility of the electron beam irradiation as a mean of red tide control in coastal water. Prorocentrum minimum, Prorocentrum micans, Cochlodinium polykrikoides, Heterosigma akashiwo, Alexnadrium catenella were selected and cultured for experiments, and red tide occurring in Tongyeong(2007. 8. 15) was also tested under the same conditions. The irradiation dose were 1 kGy, 2 kGy, 4 kGy and 8 kGy. The result showed 50~65% extinction in red tide cells was observed right after irradiation dose of 1 kGy and 86~97% within 1 day after irradiation, compared with control. Chlorophyll-a concentration of red tide was reduced by 50~64% immediately and it was drastically reduced up to 86~97% 1 day after irradiation. When the culture was irradiated at 1 kGy, 28~47% of s-protein was released immediately, and 77~138% was released 1day after irradiation. 77~212% of s-carbohydrate was excreted after 1 day while 16~45% of s-carbohydrate was excreted immediately. A transmission electron microscope(TEM) observation for the irradiated red tide revealed that the cell was destroyed and intracellular biopolymeric substance was leached out from the damaged cell as a result of electron beam irradiation. These results imply that electron beam irradiation is enable to control red tide by flocculation with extracellular biopolymer. The paralytic shellfish poisoning(PSP) toxin contents produced by Alexandrium catenella was decreased 48% by 1 kGy of electron beam irradiation compared with the unirradiated cells. As a result, electron beam irradiation was effective for detoxication as well as destruction of red tide.

• New & Renewable Energy
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• v.19 no.1
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• pp.1-11
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• 2023

A large amount of carbon monoxide (CO) is generated in circulating fluidized bed combustion, the process whereby a hot cyclone separates unburned fuel. However, calcium sulfate (CaSO₄), when combined with a high CO content, can cause fouling on the surface of the steam tube installed inside the integrated recycle heat exchangers (INTREX). In this study, CaSO₄ decomposition was investigated using 0.2-3.2 vol.% CO and 1-3 vol.% oxygen (O₂) at 850℃ for 20 min in a lab-scale fluidized bed reactor. The results show that CaSO₄ decomposes into CaS and CaO when CO gas is supplied, and SO₂ emissions increase from 135 ppm to 1021 ppm with increasing CO concentration. However, the O₂ supply delayed SO₂ emissions because the reaction between CO and O₂ is faster than that of CaSO₄; nevertheless, when supplied with CaCO₃, the intermediate product, SO₂ was significantly released, regardless of the CO and O₂ supply. In addition, agglomerated solids and yellow sulfur power were observed after solid recovery, and the reactor distributor was corroded. Consequently, a sufficient O₂ supply is important and can prevent fouling formation on the INTREX surface by suppressing CaSO₄ degradation.

• 전자공학회논문지 IE
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• v.46 no.4
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• pp.1-7
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• 2009

The final goal of ITS and ETC will be to improve the traffic efficiency and mobile safety without new road construction. DSRC system is emerging nowadays as a solution of them. China DSRC standard which was released in May 2007 has low bit rate, short message and simple MAC control. The DSRC system users want a long lifetime over 1 year with just one battery. In this paper, we propose the SoC of very low power consumption architecture. Several digital logic concept and analog power control logics were used for very low power consumption. The SoC operation mode and clock speed, operation voltage range, wakeup signal detector, analog comparator and Internal Voltage Regulator & External Power Switch were designed. We confirmed that the SoC power consumption is under 8.5mA@20Mhz, 0.9mA@1Mhz in active mode, and under 5uA in power down mode, by computer simulation. The design of SoC was finished on Aug. 2008, and fabricated on Nov. 2008 with $0.18{\mu}m$ CMOS process.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.6
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• pp.323-328
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• 2016

Pressurized membrane used for side-stream MBR process requires fouling control strategy both for normal and abnormal operation conditions for stable operation of the facilities. In this study, $85m^3/day$ of pilot-scale side-stream MBR process was constructed for the evaluation of fouling mitigation by air bubble injection into the membrane module. In addition, fouling phenomena at abnormal operation conditions of low influent and/or loading rate were also investigated. Injection of air bubble was found to be effective in delaying transmembrane pressure (TMP) increase mainly due to scouring effect on the membrane surface, resulting in expanded filtration cycle at a high flux of $40L/m^2{\cdot}h$ (LMH). At abnormal operation condition, injection of PACl (53 mg/L as Al) into the bioreactor showed 19% reduction of TMP increase. However, inhibition of nitrifying bacteria by continuous PACl injection was observed from batch experiments. In contrast, injection of powdered activated carbon (PAC, 0.6 g/L) was able to maintain the initial TMP of $0.2kg/cm^2$ for 5 days at the abnormal conditions. It may have been caused from the adsorption of extracellular polymeric substances (EPS), which was known to be excessively released during growth inhibition condition and act as the major foulants in MBR operations.

• Korean Journal of Environmental Agriculture
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• v.30 no.3
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• pp.295-303
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• 2011

BACKGROUND: Anaerobic digestion process is recently adapted technology for treatment of organic waste such as animal manure because the energy embedded in the waste can be recovered from the waste while the organic waste were digested. Ever increased demand for consumption of meat resulted in the excessive use of antimicrobials to the livestocks for more food production. Most antimicrobials administered to animals are excreted through urine and feces, which might highly affect the biological treatment processes of the animal manure. The aim of this study was to investigate the effects of antimicrobials on the efficiency of anaerobic digestion process and to clarify the interactions between antimicrobials and anaerobes. METHODS AND RESULTS: The experiment was consisted of two parts 1) batch test to investigate the effects of individual antibiotic compounds on production of methane and VFAs(volatile fatty acids), and removal efficiency of organic matter, and 2) the continuous reactor test to elucidate the effects of mixed antimicrobials on the whole anaerobic digestion process. The batch test showed no inhibitions in the rate of methane and VFAs production, and the rate of organic removal were observed with treatment at 1~10 mg/L of antimicrobials while temporary inhibition was observed at 50 mg/L treatment. In contrast, treatment of 100 mg/L antimicrobials resulted in continuous decreased in the rate of methane production and organic removal efficiency. The continuous reactor test conduced to see the influence of the mixed antimicrobials showed only small declines in the methane production and organic matter removal when 1~10 mg/L of combined antimicrobials were applied but this was not significant. In contrast, with the treatment of 50 mg/L of combined antimicrobials, the rate of organic removal efficiency in effluent decreased by 2~15% and the rate of biogas production decreased by 30%. CONCLUSION(s): The antimicrobials remained in the animal manure might not be removed during the anaerobic digestion process and hence, is likely to be released to the natural ecosystem. Therefore, the efforts to decline the usage of antimicrobials for animal farming would be highly recommended.