• 한국생물공학회:학술대회논문집
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• 2005.10a
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• pp.216-217
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• 2005

• Environmental Engineering Research
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• v.21 no.3
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• pp.265-275
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• 2016

In this study, the microalga Neochloris oleoabundans was cultivated in a sustainable manner using diluted anaerobic digestate to produce biomass as a potential biofuel feedstock. Prior to microalgae cultivation, the anaerobic digestate was characterized and several pretreatment methods including hydrogen peroxide treatment, filtration, and supernatant extraction were investigated and their impact on the removal of suspended solids as well as other organic and inorganic matter was evaluated. It was found that the supernatant extraction was the most convenient pretreatment method and was used afterwards to prepare the nutrient media for microalgae cultivation. A bench-scale experiment was conducted using multiple dilutions of the supernatant and filtered anaerobic digestate in 16 mm round glass vials. The results indicated that the highest growth of the microalga N. oleoabundans was achieved with a total nitrogen concentration of 100 mg N/L in the 2.29% diluted supernatant in comparison to the filtered digestate and other dilutions.

• Journal of Marine Bioscience and Biotechnology
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• v.8 no.1
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• pp.39-44
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• 2016

The microalgae have been studied for a source of biodiesel production. It is important to select the microalgae, which grows rapidly in local environmental conditions such as temperature range and ingredient of local seawater. The aim of this study was isolating microalga, which has rapid growth rate and high FAME contents in wide temperature ranges, for microalgal offshore cultivation in Korea, one of the country with four distinct seasons. Firstly, we had isolated a green microalga, Tetraselmis sp. KCTC12236BP, which has faster growth rate in low temperature (5 and $10^{\circ}C$) than Tetraselmis suecica and Dunaliella tertiolecta LB999 from Young Heung Island, Incheon, Korea. This microalga was cultivated in outdoor circulated tank photobioreactor (CT-PBR). As a result, this microalga could grow in wide temperature ranges (6 to $29^{\circ}C$), outdoors. After that, the biomass was recovered, and 13.2 g biodiesel could be acquired from 110 g dry biomass. These results indicate that the isolated microalga, Tetraselmis sp. KCTC12236BP is proper to biodiesel production using outdoor cultivation in Korea for all seasons.

• Journal of Microbiology and Biotechnology
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• v.25 no.2
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• pp.238-246
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• 2015

A unicellular red microalga was isolated from environmental freshwater in Korea, and its morphological, molecular, and biochemical properties were characterized. Morphological analysis revealed that the isolate was a unicellular biflagellated green microalga that formed a non-motile, thick-walled palmelloid or red aplanospore. To determine the taxonomical position of the isolate, its 18S rRNA and rbcL genes were sequenced and phylogenetic analysis was performed. We found that the isolate was clustered together with other related Haematococcus strains showing differences in the rbcL gene. Therefore, the isolated microalga was classified into the genus Haematococcus, and finally designated Haematococcus sp. KORDI03. The microalga could be cultivated in various culture media under a broad range of pH and temperature conditions. Compositions of the microalgal cellular components were analyzed, and its protein, carbohydrate, and lipid compositions were estimated to be 21.1 ± 0.2%, 48.8 ± 1.8%, and 22.2 ± 0.9%, respectively. In addition, D-glucose and D-mannose were the dominant monosaccharides in the isolate, and its amino acids were composed mainly of aspartic acid, glutamic acid, alanine, and leucine. Moreover, several polyunsaturated fatty acids accounted for about 80% of the total fatty acids in Haematococcus sp. KORDI03, and the astaxanthin content in the red aplanospores was estimated to be 1.8% of the dry cell weight. To the best of our knowledge, this is the first report of an Haematococcus sp. isolated from Korea, which may be used for bioresource production in the microalgal industry.

• Natural Product Sciences
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• v.6 no.3
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• pp.122-125
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• 2000

Allenic and epoxy carotenoid, fucoxanthin (1) was isolated from the marine bacillariophycean microalga Hantzschia marina and the structure was assigned on the basis of comprehensive spectroscopic analyses. Fucoxanthin was detected only from diatom among three families (green algae, diatom and blue-green algae) of the marine microalgae tested. Fucoxanthin showed free radical scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) and peroxynitrite $(ONOO^-)$ with $IC_{50}$ values of $32\;{\mu}M\;and\;60\;{\mu}M$, respectively.

• Fisheries and Aquatic Sciences
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• v.16 no.3
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• pp.187-194
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• 2013

Microalgae are sensitive indicators of environmental changes, and hence they are widely used in environmental risk assessments and for the development of discharge guidelines. Here we evaluated the toxicity of metals and endocrine-disrupting chemicals (EDCs) to the marine green microalga, Tetraselmis suecica. The toxicants investigated included the metals, Cu, Ni, and Pb; and the EDCs, bisphenol A (BPA), endosulfan (ES), and polychlorinated biphenyl (PCB). The endpoints were variations in cell counts and chlorophyll a levels. T. suecica displayed a varied pattern of sensitivity to the toxicants. Based on the 72-h median effective concentration ($EC_{50}$), ES (0.045 mg/L) was most toxic to T. suecica, followed by PCB (3.96 mg/L) and Pb (9.62 mg/L). Interestingly, T. suecica was relatively tolerant to Cu (43.03 mg/L). The 72-h $EC_{50}$ values of Ni and BPA were approximately 16 mg/L. Our data suggest that this species may be relatively tolerant to most of the chemicals within their permissible limits in the environment.

• Fisheries and Aquatic Sciences
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• v.8 no.1
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• pp.1-5
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• 2005

Cell growth of the marine microalga Tetraselmis suecica was regulated by the addition of seaweed extracts in its culture medium. Of 26 species of seaweed tested, water-soluble extracts from Monostroma nitidum and Pachymeniopsis elliptica and methanol-soluble extract from Sargassum confilsum enhanced the growth of T suecica cells. The water extract of M. nitidum was the most effective, producing up to a 2-fold increase in cell density with the addition of 1 mg/mL of extract to the culture medium. Cell size, gross biochemical composition, fatty acids, and digestion efficiency all differed marginally between cultures of T suecica grown with and without the M. nitidum extract.

• Journal of Microbiology and Biotechnology
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• v.24 no.4
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• pp.522-533
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• 2014

Bionanotechnology has revolutionized nanomaterial synthesis by providing a green synthetic platform using biological systems. Among such biological systems, microalgae have tremendous potential to take up metal ions and produce nanoparticles by a detoxification process. The present study explores the intracellular and extracellular biogenic syntheses of silver nanoparticles (SNPs) using the unicellular green microalga Scenedesmus sp. Biosynthesized SNPs were characterized by AAS, UV-Vis spectroscopy, TEM, XRD, FTIR, DLS, and TGA studies and finally checked for antibacterial activity. Intracellular nanoparticle biosynthesis was initiated by a high rate of $Ag^+$ ion accumulation in the microalgal biomass and subsequent formation of spherical crystalline SNPs (average size, 15-20 nm) due to the biochemical reduction of $Ag^+$ ions. The synthesized nanoparticles were intracellular, as confirmed by the UV-Vis spectra of the outside medium. Furthermore, extracellular synthesis using boiled extract showed the formation of well scattered, highly stable, spherical SNPs with an average size of 5-10 nm. The size and morphology of the nanoparticles were confirmed by TEM. The crystalline nature of the SNPs was evident from the diffraction peaks of XRD and bright circular ring pattern of SAED. FTIR and UV-Vis spectra showed that biomolecules, proteins and peptides, are mainly responsible for the formation and stabilization of SNPs. Furthermore, the synthesized nanoparticles exhibited high antimicrobial activity against pathogenic gram-negative and gram-positive bacteria. Use of such a microalgal system provides a simple, cost-effective alternative template for the biosynthesis of nanomaterials in a large-scale system that could be of great use in biomedical applications.

• Biotechnology and Bioprocess Engineering:BBE
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• v.8 no.6
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• pp.331-337
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• 2003

Unicellular green algae of the genus Dunaliella thrive in extreme environmental conditions such as high salinity, low pH, high irradiance and subzero temperatures. Species of Dunaliella are well known in the alga biotechnological industry and are employed widely for the production of valuable biochemicals, such as carotenoids. Some strains of Dunaliella are cultivated commercially in large outdoor ponds and are harvested to produce dry algal meals, such as polyunsaturated fatty acids and oils for the health food industry, and coloring agents for the food and cosmetic industries. During the past decade, the advances in molecular biology and biochemistry of microalgae, along with the advances in biotechnology of microalgal mass cultivation, enabled this microalga to become a staple of commercial exploitation. In particular, the advent of molecular biology and mutagenesis in Dunaliella has permitted enhancements in the carotenoids content of this green alga, making it more attractive for biotechnological applications. Accordingly, the present review summarizes the recent developments and advances in biotechnology of carotenoid production in Dunaliella.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.181-184
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• 2001

The biological fixation of carbon dioxide using microalgae have many advantages over chemicals and remove carbon dioxide simultaneously. A ketocarotenoid astaxanthin is hyper-accumulated in the green freshwater microalga, Haematococcus pluvialis. In the present study, the combine effects of carbon dioxide concentration and light intensity on the growth of H. pluvilais were investigated. The carbon dioxide concentration above 10% caused a severe inhibition and around 5% is optimal for growth. Adaptation to high concentration of carbon dioxide enhanced the $CO_2$ tolerance. Specific growth rate calculated differently based upon cell number or dry weight because of the distinctive life cycle patterns of H. pluvialis : small-sized motile green cell and thick cell walled red cyst cell. Based on the light dependence of H. pluvialis, internally illuminated air-lift photobioreactor was designed and operated. Gradual increase of light supply gave more active growth and more effective productivity of astaxanthin than constant light supply.