Biomedical subjects

Seung-Wook Kim

Publications and source records attributed to Seung-Wook Kim.

9 recordsLinked to original sources

PubMed2006

Purification and characterization of prodigiosin produced by integrated bioreactor from Serratia sp. KH-95.

To date, prodigiosin and its analogues which have been shown to have anticancer, cytotoxic and immunosuppressive activities have been isolated from Serratia, Pseudomonas and Streptomyces species, and chemically synthesized. In a previous study, the red pigment content in Serratia sp. KH-95 was enhanced using a casein-enriched medium. Recently, an integrated bioreactor with an internal adsorbent has been developed to increase the production yield and allow easy recovery of the pigment. Thus, this study focused on both purifying and identifying a single red pigment from several pigments attached to the adsorbent in an integrated bioreactor. The red pigment was extracted directly from the internal adsorbent using acidified methanol and phase separation. Subsequently, it was purified by silica gel chromatography and high performance liquid chromatograph (HPLC). As a result, pure prodigiosin was identified by structural studies as a pigment. Also, this downstream procedure that uses the integrated bioreactor can be applied to the direct production and purification of other prodigiosin analogues and hydrophobic alkaloid compounds from several microorganisms.

Bioreactors↗

PubMed2005

Nonclassical action of retinoic acid on the activation of the cAMP response element-binding protein in normal human bronchial epithelial cells.

Vitamin A (retinol) is essential for normal regulation of cell growth and differentiation. We have shown that the retinol metabolite retinoic acid (RA) induces mucous cell differentiation of normal human tracheobronchial epithelial (NHTBE) cells. However, early biological effects of RA in the differentiation of bronchial epithelia are largely unknown. Here, we showed that RA rapidly activated cAMP response element-binding protein (CREB). However, RA did not use the conventional retinoic acid receptor (RAR)/retinoid X receptor (RXR) to activate CREB. RA activated CREB in NHTBE and H1734 cells in which RARs/RXR were silenced with small interfering RNA (siRNA) targeting RAR/RXR expression or deactivated by antagonist. Inhibition of protein kinase C (PKC) or extracellular regulated kinase (ERK1/2) blocked the RA-mediated activation of CREB. In addition, depletion of p90 ribosomal S6 kinase (RSK) via siRSK1/2 completely abolished the activation, suggesting that PKC, ERK, and RSK are required for the activation. Altogether, this study provides the first evidence that RA rapidly activates CREB transcription factor via PKC, ERK, and RSK in a retinoid receptor-independent manner in normal bronchial epithelial cells. This noncanonical RA signaling pathway may play an important role in mediating early biological effects in the mucociliary differentiation of bronchial epithelia.

Bronchi↗

PubMed2005

High-level production of astaxanthin by Xanthophyllomyces dendrorhous mutant JH1 using statistical experimental designs.

Medium composition was optimized for high-level production of astaxanthin by Xanthophyllomyces dendrorhous mutant JH1 using statistical experimental designs. Glucose and yeast extract were the most important factors affecting astaxanthin production. Glucose 3.89%, yeast extract 0.29%, KH2PO4 0.25%, MgSO4 0.05%, MnSO4 0.02%, and CaCl2 0.01% were optimum for high-level production of astaxanthin. Under optimized conditions, the maximum concentration of astaxanthin obtained after 7 d of cultivation was 36.06 mg/l. The concentration of astaxanthin predicted by a polynomial model was 36.16 mg/l.

Basidiomycota↗

PubMed2003

Bioremediation of 2,4,6-trinitrotoluene contaminated soil in slurry and column reactors.

The bioremediation of 2,4,6-trinitrotoluene (TNT) contaminated soil was performed on a laboratory scale. To compare bioremediation methods, a soil slurry reactor and a soil column reactor were operated and the effects of supplemental sources were investigated. Optimal conditions for the two bioremediation systems for the removal of TNT were obtained. In the soil slurry reactor, about 60% of the 1000 mg/kg TNT contaminated soil was degraded after 10 d, nearly complete biodegradation (>99%) was achieved within 25 d, and the microorganisms grew and reached a maximum of 9.5 x 10(9) CFU/ml at 15 d. In the soil column reactor, about 50% of the 1000 mg/kg TNT contaminated soil was degraded after 25 d and nearly complete biodegradation (>99%) was achieved within 60 d. Microorganisms grew and reached a maximum of 9.8 x 10(10) CFU/g soil at 40 d. These results should help in determining the best bioremediation method and improving the design and operation of large scale clean up of contaminated sites by bioremediation systems.

Journal Article↗

PubMed2003

Effects of various pretreatments for enhanced anaerobic digestion with waste activated sludge.

The purpose of this study was to enhance the efficiency of anaerobic digestion with waste activated sludge (WAS) by batch experiments. We studied the effects of various pretreatment methods (thermal, chemical, ultrasonic and thermochemical pretreatments) on the biogas production and pollutants reduction owing to solubilization enhancement, particle size reduction, increased soluble protein, and increased soluble COD. The thermochemical pretreatment gave the best results, i.e., the production of methane increased by more than 34.3% and soluble COD (SCOD) removal also increased by more than 67.8% over the control. In this case, the biogas production, methane production and the SCOD removal efficiency were about 5037 l biogas/m3 WAS, 3367 l methane/m3 WAS and 61.4%, respectively. Therefore, it is recognized that higher digestion efficiencies of the WAS were obtained through thermochemical pretreatment of the sludge.

Journal Article↗

PubMed2003

COD reduction and decolorization of textile effluent using a combined process.

This study showed the effectiveness of biological pretreatment involving appropriate microorganisms and suitable support media in a combined process. The combined process consists of biological pretreatment, chemical coagulation and electrochemical oxidation. COD and color were reduced by 95.4% and 98.5% by the combined process, respectively.

Journal Article↗

PubMed2003

Optimization for biodegradation of 2,4,6-trinitrotoluene (TNT) by Pseudomonas putida.

In this study, a strain of Pseudomonas putida KP-T202, isolated from the soil in a contaminated site, degraded 2,4,6-trinitrotoluene (TNT). In order to make this biodegradation process commercially feasible and reduce biodegradation time, optimal environmental factors are determined. At an initial concentration of 100 mg/l, TNT was totally degraded within 15 h under aerobic conditions. The optimal conditions for the biodegradation of TNT were found to be 30 degrees C, pH 7, 1% corn steep liquor (CSL), 0.025% NH,CI and 0.1% Tween 80; the reaction rate constant was 0.348 h(-1) These environmental conditions can be used to improve the efficiency of large-scale reactors for the treatment of TNT-contaminated wastewater and soil. In addition, the intermediates were identified as 2-amino-4,6-dinitrotoluene, 4-amino-2,6-dinitrotoluene, 2,4-dinitrotoluene and 2,6-dinitrotoluene.

Journal Article↗

PubMed2002

Effects of SO2 and NO on growth of Chlorella sp. KR-1.

Effects of the toxic compounds in flue gas, SOx and NOx, on growth of Chlorella sp. KR-1 have been determined. Although growth of KR-1 was suppressed by the toxic compounds, KR-1 exhibited excellent tolerances to SOx compared to other algal strains. When Chlorella KR-1 was cultured with the model gas containing 60 ppm SO2, the linear growth rate was 1.24 g/l day which is about 25% lower than that of the control culture aerated with the gas mixture containing no toxic compounds, SO2 and NO. KR-1 could grow even with the model gas containing 100 ppm SO2 and the linear growth rate of KR-1 in the culture was 0.78 g/l day. The period for lag phase was increased with increasing of SO2 concentration that also resulted in the decrease of the linear growth rate and the maximum cell concentration. Direct CO2 fixation by Chlorella KR-1 has been successfully done using actual flue gases from a liquified natural gas (LNG)- or diesel-fueled boiler. These results indicated that Chlorella KR-1 may be applied for direct CO2 fixation from actual flue gas.

Air Pollutants↗

PubMed2002

Biokinetic parameter estimation for degradation of 2,4,6-trinitrotoluene (TNT) with Pseudomonas putida KP-T201.

The purpose of this study is to determine the biodegradation kinetics of 2,4,6-trinitrotoluene (TNT) by a newly isolated microorganism. Hundreds of microorganisms were isolated from explosives-contaminated soil in Korea. Examination of culture tests revealed that a few species of microorganisms have good ability to degrade TNT. The most efficient one was selected and identified as Pseudomonas putida KP-T201. Biodegradation of TNT was tested in a batch reactor using a pure culture of P. putida KP-T201. The effect of different concentrations of TNT on the rate of bacterial biodegradation was investigated. The Haldane equation seems to be an adequate expression for the cell growth data, and the kinetic constants obtained were mu(m)=0.65 h(-1), K(S)=0.62 mgl(-1), and K(i)=115 mgl(-1). The dependence of the bacterial specific growth rate on the concentration of TNT could be explained as a conventional model of substrate inhibition.

Journal Article↗