• Microbiology and Biotechnology Letters
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• v.48 no.3
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• pp.328-336
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• 2020

Parachlorella sp. is an efficient fatty acid producer that can be used in the production of biofuels, feeds, and fertilizers. Microalgae show varying responses to culture conditions, even those within the same species. In this study, growth and fatty acid composition of a newly isolated Parachlorella sp. from the Nakdong river of Korea in different culture media were investigated. The microalga was cultivated in 400 ml bubble column photobioreactors using BG-11, BBM, TAP, and modified TAP (MTAP) media. It was shown that using BBM led to greater fatty acid accumulation (34%), while using TAP medium led to greater biomass productivity (0.34 g/l/day). Composition of the TAP medium was modified to have the N:P ratio of BBM while also varying concentrations of N and P to improve fatty acid productivity. One of the modified TAP media, MTAP-1 (104.8 mgN/l, 135.2 mgP/l, N:P ratio = 0.77), showed the highest fatty acid concentration of 0.69 ± 0.04 g/l, while those from TAP and BBM were 0.48 ± 0.06 g/l and 0.40 ± 0.02 g/l, respectively. The results showed that microalgal fatty acid productivity could be enhanced by changing the N:P ratio and concentrations.

• Applied Chemistry for Engineering
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• v.26 no.5
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• pp.587-592
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• 2015

Activated carbons (ACs) were treated by fluorination to improve the adsorption property of toluene gas among volatile organic compounds (VOCs). The pore characteristics and surface properties of these activated carbons were evaluated by BET and XPS and the adsorption property and removal efficiency of toluene gas was investigated by gas chromatography. The breakthrough time of fluorinated ACs was increased about 27% compared to that of untreated ACs when the toluene gas of 100 ppm was flowed at a flow rate of $300cm^3/min$. Fluorinated AC of 0.1 g adsorbent totally adsorbed toluene gas in 100 ppm to 100 % during the adsorption time in 19 h. These results can be used as a treatment technology or removal of carcinogenic materials such as toluene.

• Journal of Microbiology and Biotechnology
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• v.34 no.2
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• pp.467-475
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• 2024

ρ-Hydroxyacetophenone is an important and versatile compound that has been widely used in medicine, cosmetics, new materials, and other fields. At present, there are two ways to obtain ρ-hydroxyacetophenone. One is to extract it from plants, such as Artemisia capillaris Thunb and Cynanchum otophyllum Schneid, and the other is to synthesize it by using chemical methods. Of these two methods, the second is the main one, although it has problems, such as flammable and explosive reagents, difficult separation of by-products, and harsh reaction conditions. To solve these issues, we adopted genetic engineering in this study to construct engineered Escherichia coli containing Hped gene or EbA309 gene. Whole-cell biotransformation was conducted under the same conditions to select the engineered E. coli with the higher activity. Orthogonal tests were conducted to determine the optimal biotransformation condition of the engineered E. coli. The results showed that the optimal condition was as follows: substrate concentration of 40 mmol/l, IPTG concentration of 0.1 mmol/l, an induction temperature of 25℃, and a transformation temperature of 35℃. Under this condition, the effects of transformation time on the ρ-hydroxyacetophenone concentration and cell growth were further studied. We found that as the transformation time extended, the ρ-hydroxyacetophenone concentration showed a gradually increasing trend. However, when the ρ-hydroxyacetophenone concentration increased to 1583.19 ± 44.34 mg/l in 24 h, cell growth was inhibited and then entered a plateau. In this research, we realized the synthesis of ρ-hydroxyacetophenone by biotransformation, and our findings lay a preliminary foundation for further improving and developing this method.

• Journal of Microbiology and Biotechnology
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• v.28 no.2
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• pp.267-274
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• 2018

Lipids in microalgae are energy-rich compounds and considered as an attractive feedstock for biodiesel production. To redirect carbon flux from competing pathways to the fatty acid synthesis pathway of Tetraselmis sp., we used three types of chemical inhibitors that can block the starch synthesis pathway or photorespiration, under nitrogen-sufficient and nitrogen-deficient conditions. The starch synthesis pathway in chloroplasts and the cytosol can be inhibited by 3-(3,4-dichlorophenyl)-1,1-dimethylurea and 1,2-cyclohexane diamine tetraacetic acid (CDTA), respectively. Degradation of glycine into ammonia during photorespiration was blocked by aminooxyacetate (AOA) to maintain biomass concentration. Inhibition of starch synthesis pathways in the cytosol by CDTA increased fatty acid productivity by 27% under nitrogen deficiency, whereas the blocking of photorespiration in mitochondria by AOA was increased by 35% under nitrogen-sufficient conditions. The results of this study indicate that blocking starch or photorespiration pathways may redirect the carbon flux to fatty acid synthesis.

• Journal of Korean Society on Water Environment
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• v.32 no.3
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• pp.303-309
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• 2016

This study aimed to assay the biological removal of TDS (total dissolved solids) from RO (reverse osmosis) rejected water. Following bio-sorption of TDS with AGS (aerobic granular sludge), the effects of TDS on biological nitrogen removal were examined. The bio-sorption of TDS after AGS treatment was confirmed by checking for TDS removal efficiency and surface analysis of microorganisms with SEM and EDS. Then, the effects of TDS on biological nitrogen removal and the denitrification efficiency were evaluated using the MBR reactor. According to the results, the bio-sorption of TDS with AGS was 0.1 mg TDS/mg AGS, and we confirmed that the microorganism surfaces had adsorbed the TDS. Biological nitrogen removal efficiency was measured at inhibiting denitrification at 4,000 mg/L of TDS-injected material. Based on this study, it is necessary to pretreat TDS-containing RO rejected water and to maintain TDS concentration lower than a specific value (≤4,000 mg/L), when considering biological nitrogen removal.

• 한국생물공학회:학술대회논문집
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• 2005.10a
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• pp.904-909
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• 2005

To optimize the removal of free fatty acid in crude vegetable oil, response surface methodology was applied to determine the effects of five level-four factors and their reciprocal interactions on removal of free fatty acid. A total of 30 individual experiments were performed, which were designed to study reaction temperature, reaction time, catalyst amount and methanol amount. A statistical model predicted that the highest removal yield of free fatty acid was 99.8%, at the following optimized reaction conditions: a reaction temperature of 64.99$^{\circ}C$, a reaction time of 36.20 mins., an catalyst amount of 13.01% (w/v), and a methanol amount of 15% (v/v). Using these optimal factor values under experimental conditions in three independent replicates, the average removal yield was well within the value predicted by the model.

• Molecules and Cells
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• v.25 no.4
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• pp.494-503
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• 2008

Many therapeutic glycoproteins have been successfully generated in plants. Plants have advantages regarding practical and economic concerns, and safety of protein production over other existing systems. However, plants are not ideal expression systems for the production of biopharmaceutical proteins, due to the fact that they are incapable of the authentic human N-glycosylation process. The majority of therapeutic proteins are glycoproteins which harbor N-glycans, which are often essential for their stability, folding, and biological activity. Thus, several glyco-engineering strategies have emerged for the tailor-making of N-glycosylation in plants, including glycoprotein subcellular targeting, the inhibition of plant specific glycosyltranferases, or the addition of human specific glycosyltransferases. This article focuses on plant N-glycosylation structure, glycosylation variation in plant cell, plant expression system of glycoproteins, and impact of glycosylation on immunological function. Furthermore, plant glyco-engineering techniques currently being developed to overcome the limitations of plant expression systems in the production of therapeutic glycoproteins will be discussed in this review.

• Applied Chemistry for Engineering
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• v.21 no.3
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• pp.243-251
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• 2010

Nitrogen oxides (NOx) in combustion flue gas are currently mitigated by chemical processes such as catalytic reduction, absorption and adsorption. However, development of environmentally sustainable biological processes is necessary in the near future. In this paper, the up-to-dated R&D trend of biological methodologies regarding NOx removal was reviewed, and their advantages and disadvantages were discussed. The principles and applications of bacterial system including nitrification and denitrification and photosynthetic microalgae system were compared. In order to enhance biological treatment rate and performance, the insoluble nitric oxide (NO) should be first absorbed using a proper solubilization agent, and then microbial degradation or fixation is to be followed. The use of microalgal system has a good prospect because it can fix $CO_2$ and NOx simultaneously and requires no additional carbon for energy source.

• 한국생물공학회:학술대회논문집
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• 2005.10a
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• pp.842-842
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• 2005

• 한국당과학회:학술대회논문집
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• 2006.11a
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• pp.61-62
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• 2006