• 한국생물공학회:학술대회논문집
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• 2005.10a
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• pp.659-660
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• 2005

• Proceedings of the Korean Society of Life Science Conference
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• 2003.10a
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• pp.88-88
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• 2003

• Journal of Microbiology and Biotechnology
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• v.28 no.3
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• pp.432-438
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• 2018

Microalgae hold promise as a renewable energy source for the production of biofuel, as they can convert light energy into chemical energy through photosynthesis. However, cost-efficient harvest of microalgae remains a major challenge to commercial-scale algal biofuel production. We first investigated the potential of electrolytic water as a flocculant for harvesting Tetraselmis sp. Alkaline electrolyzed water (AEW) is produced at the cathode through water electrolysis. It contains mineral ions such as $Na^+$, $K^+$, $Ca^{2+}$, and $Mg^{2+}$ that can act as flocculants. The flocculation activity with AEW was evaluated via culture density, AEW concentration, medium pH, settling time, and ionic strength analyses. The flocculation efficiency was 88.7% at 20% AEW (pH 8, 10 min) with a biomass concentration of 2 g/l. The initial biomass concentration and medium pH had significant influences on the flocculation activity of AEW. A viability test of flocculated microalgal cells was conducted using Evans blue stain, and the cells appeared intact. Furthermore, the growth rate of Tetraselmis sp. in recycled flocculation medium was similar to the growth rate in fresh F/2 medium. Our results suggested that AEW flocculation could be a very useful and affordable methodology for fresh biomass harvesting with environmentally friendly easy operation in part of the algal biofuel production process.

• Journal of Marine Bioscience and Biotechnology
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• v.9 no.2
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• pp.35-42
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• 2017

Hydrothermal liquefaction of lipid-extracted Tetraselmis sp. feedstock containing 80 wt.% water was conducted in a batch reactor at different temperatures (300, 325, and $350^{\circ}C$) and reaction times (5, 10, 20, 40, and 60 min). The biocrude yield, elemental composition and higher heating value obtained at various reaction conditions were used to predict the optimum conditions for maximizing energy recovery of biocrude with good quality. A maximum energy recovery of 67.6% was obtained at $325^{\circ}C$ and 40 min with a high energy density of 31.8 MJ/kg and lower contents of nitrogen and oxygen. Results showed that reaction conditions of $325^{\circ}C$, 40 min was most suitable for maximizing energy recovery while at the same time achieving improved quality of biocrude.

• Journal of Microbiology and Biotechnology
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• v.28 no.6
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• pp.931-937
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• 2018

Glycosyltransferases (GTs) from microbes are an emerging and rich source for efficient glycol-transformation of natural/unnatural compounds. Here, we probed the catalytic capability and substrate promiscuity of BmmGT1 from marine-derived Bacillus methylotrophicus B-9987. The regioselectivity of BmmGT1 on macrolactin A (1) was explored by optimization of the reaction conditions, in which a series of O-glycosylated macrolactins (1a-1e) were generated, including two new di/tri-O-glucosyl analogs (1b and 1e). Furthermore, BmmGT1 was able to catalyze the glycosylation of the thiol (S-) or amine (N-) sites of phenolic compounds (2 and 3), leading to the generation of N- (2a) or S-glycosides (3a and 3b). The present study demonstrates that BmmGT1 could serve as a potential enzyme tool for O-, N-, or S-glycosyl structural diversification of compounds for drug discovery.

• Journal of Marine Bioscience and Biotechnology
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• v.6 no.2
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• pp.62-67
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• 2014

In this study, we investigated the bioactive substances of the Alcalase hydrolysate obtained from fishery processing by-products in Jeju by measuring bioactivities including radical scavenging acitivty, cytoprotective activity against 2,2-azobis-(2-amidino-propane) dihydrochloride (AAPH), and ACE inhibitory activity. This study is important because of utilization of unused fishery processing by-products in Jeju. The Alcalase hydrolysate was prepared through the hot water extraction and enzymatic hydrolysis, and then further separation of the Alcalase hydrolysate was performed by ultrafiltration using 10 kDa molecular weight cut-off membrane. The Alcalase hydrolysate showed the relatively higher DPPH and peroxyl radical scavenging activity ($IC_{50}$ value; 1.30 mg/ml and 0.888 mg/ml, respectively). Also, the Alcalase hydrolysate showed the ACE inhibitory activity with 1.87 mg/ml of $IC_{50}$ value. These biological activities are increased over 1.2 or 2.5 times through the ultrafiltration of the Alcalase hydrolysate. Therefore, the Alcalase hydrolysate obtained from fishery processing by-products in Jeju and the different molecular weight fractions should be given consideration for food and cosmetics ingredient. Furthermore, this research on the utility of fishery processing by-products might be a useful tool into the industry.

• Journal of Marine Bioscience and Biotechnology
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• v.11 no.1
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• pp.23-28
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• 2019

For successful microalgal biodiesel production, the strain should be selected carefully. Fast growth rate and high fatty acid contents are desired traits for algal biodiesel production. In ocean cultivation of microalgae, seawater temperature slowly changes over seasons, and rotating algal strains in accordance with their optimal temperature could improve overall productivity. Additionally, use of indigenous strain is preferred to alleviate potential impacts on the environment. In this study, five strains of Tetraselmis sp. from nearshore of Youngheung Island, Incheon, Korea, were isolated during winter and characterized for their growth patterns and fatty acid compositions in the low temperatures ($5-15^{\circ}C$). The five strains showed various characteristics in optimal growth temperature, fatty acid contents, and compositions. Compared with a strain of Tetraselmis sp., isolated from Ganghwa island in a previous study, a rapid-growing strain with 237% higher biomass productivity and an oleaginous strain with twice higher fatty acid contents at $10^{\circ}C$ were isolated. The oleaginous Tetraselmis strain showed the highest fatty acid productivity among the strains, having 438% higher productivity than the previous strain. Using the new isolates in the seasons with low seawater temperature would improve microalgal fatty acid productivity in ocean cultivation.

• Journal of Microbiology and Biotechnology
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• v.27 no.6
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• pp.1078-1089
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• 2017

Biofilm formation of Staphylococcus aureus is one of its mechanisms of drug resistance. Anti-biofilm screening of 106 compounds from marine-derived fungi displayed that 12 compounds inhibited S. aureus biofilm formation by >50% at the concentration of $100{\mu}g/ml$, and only secalonic acid D (SAD) and B inhibited by >90% at $6.25{\mu}g/ml$ without inhibiting cell growth after 24-h incubation. Meanwhile, it was found that the double bond between C-1 and C-10 of citrinin derivatives and the C-C connection position of two chromone monomers may be important for their anti-biofilm activities. Moreover, SAD slightly facilitated biofilm eradication and influenced its architecture. Furthermore, SAD slowed the cell growth rate in the preceding 18-h incubation and differentially regulated transcriptional expression of several genes, such as agr, isaA, icaA, and icaD, associated with biofilm formation in planktonic and biofilm cells, which may be the reason for the anti-biofilm activity of SAD. Finally, SAD acted synergistically against S. aureus growth and biofilm formation with other antibiotics. These findings indicated that various natural products from marine-derived fungi, such as SAD, could be used as a potential biofilm inhibitor against S. aureus.

• Korean Journal of Food Science and Technology
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• v.43 no.4
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• pp.464-468
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• 2011

Halocynthia roretzi is one of the most important cultured marine species on the southern coast of Korea. Samples were extracted using methanol (ME), ethanol (EE) and water (WE) to evaluate the antioxidant activities and antilipase activity in Halocynthia roretzi extracts. Antioxidant potentials of the samples were determined by poly-phenol content, flavonoid content, free radical scavenging activity, reducing potential, and chelating activity. The ME showed significant scavenging activity (1176 ${\mu}g/mL$ IC50 for DPPH, and 895 ${\mu}g/mL$ IC50 for ABTS assay). The IC50 for lipase inhibition activity was 12,021, 6,004, and 14,979 ${\mu}g/mL$ in the ME, EE, and WE, respectively. In conclusion, Halocynthia roretzi extracts exhibited antioxidant activities and anti-lipase activity. These results suggest that Halocynthia roretzi extracts can be potentially used as a source of antioxidant and antiobesity agents.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.3
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• pp.408-412
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• 1997

The cytogenetic analysis of river puffer, Takifugu obscurus belongs to Family Tetraodontidae, was performed. The chromosome number of T. obscurus was 44 and the fundamental number was 64. Heteromorphic sex chromosomes were not found. The mean cellular size and nuclear size were $11.01\times7.95{\mu}m$ and $4.05\times3.15{\mu}m$, respectively. The mean surface area and volume in cell and nucleus were $68.76{\mu}m^2\;and\;366.00{\mu}m^3,\;10.06{\mu}m^2\;and\;21.36{\mu}m^3$, respectively. The number of erythrocyte of both female and male was $12\~13\times10^5/m\ell$. Gill tissues from diploid individuals had cells with one or two nucleoli. These cytogenetic studies should be used for cytotaxonomy and as a valuable estimation of polyploidy to come in T. obscurus.