• ALGAE
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• 제19권3호
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• pp.161-174
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• 2004

Phonological, morphological and molecular characteristics of Spatoglossum pacificum Yendo are examined. S. pacificum has an annual life cycle composed of saprophytes with apparent absence of male and female gametophytes in Korea. The seasonal growth of this species explains that the annual growth is closely related to the monthly variation of water temperature. S. pacificum has protruding reproductive structures above the outmost cortical layer. Although this observation is restricted to several species, reproductive structures on the thallus can make S. pacificurn distinguishable from S. crassum and S. lacturn. The morphogenesis of a midrib at the base of S. pacificum in this study is the same as those of Dictyopteris but different from those of S. crassum and S. lacturn, suggesting that S. pacificum is closely related to Dictyopteris. In the comparison of plastid gene sequences among species of Spatoglossum and Dictyopteris, S. pacificum is more similar to D. divaricata and D. undulate than those of S. crassum in rbcL, rbcS, psbA and psaA. This result is congruent with the anatomical characteristic of a midrib at the base of the thallus and the protrusion of reproductive organs on the thallus. The phylogenetic relationship based on these plastid genes also shows that S. pacifism is included in Dictyotpteris Glade and separated from S. crassum. We propose the new combination of Dictyopteris pacifica (Yendo) I.K. Hwang, H.S. Kim et W.J. Lee, comb. nov. based on the differences of anatomical characteristics of the midrib, the existence of reproductive organs on thallus and the molecular analyses.

• ALGAE
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• 제35권3호
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• pp.277-292
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• 2020

Omega-3 fatty acids, including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are polyunsaturated fatty acids beneficial to human health. A limited number of microalgae have been used for commercial omega-3 production, which necessitates the identification of new microalgae with high omega-3 contents. We explored the fatty acid composition and EPA and DHA contents of the mixotrophic dinoflagellate Gymnodinium smaydae fed with the optimal algal prey species Heterocapsa rotundata. Cells of G. smaydae were found to be rich in omega-3 fatty acids. In particular, the DHA content of G. smaydae was 21 mg g^-1 dry weight, accounting for 43% of the total fatty acid content. The percentage of DHA in the total fatty acid content of G. smaydae was the highest among the reported microalgae except for Crypthecodinium cohnii. Moreover, to determine if the prey supply interval affected the growth rate of G. smaydae and its fatty acid content, three different prey supply intervals (daily, once every 2 d, and once for 4 d) were tested. Daily prey supply yielded the highest total fatty acid and DHA contents in G. smaydae. Furthermore, we successfully produced high-density G. smaydae cultures semi-continuously for 43 d with daily prey supply. During the semi-continuous cultivation period, the highest density of G. smaydae was 57,000 cells mL^-1, with an average growth rate of 0.7 d^-1. Taken together, the percentage of EPA and DHA in the total fatty acid content was maintained in the range of 54.2-56.9%. The results of this study support G. smaydae as a promising microalgal candidate for commercial DHA production and demonstrate that daily supply of prey can efficiently produce high-density G. smaydae cultures for more than a month.

• Journal of Plant Biotechnology
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• 제44권3호
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• pp.287-295
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• 2017

Water temperature is one of the major factors that impacts the growth and life cycle of Pyropia tenera, one of the most valuable and cultivated marine red algae belonging to Bangiales (Rhodophytes). We analyzed transcriptome from gametophyte of P. tenera under normal and high temperature conditions, and identified four small heat shock proteins (sHSPs). They have no significant amino acid sequence homology with known proteins in public databases except PhsHSP22 from Pyropia haitanensis. PtsHSP19.3 gene responded to high temperature but slightly or not to desiccation, freezing or high salt condition. When the PtsHSP19.3 gene was overexpressed in Chlamydomonas reinhardtii, transformed Chlamydomonas lines revealed much higher growth rate than that of control cells under heat stress condition. Transformed cells also grew well in those of the control cell onto the medium containing high salt or $H_2O_2$. When the PtsHSP19.3 was fused to GFP and introduced into tobacco protoplast, fluorescence was detected at several spots. Results indicate that PtsHSP19.3 may form super-molecular assembles and be involved in tolerance to heat stress.

• 한국양식학회지
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• 제18권2호
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• pp.86-91
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• 2005

I. galbana, P. parvum 및 P. patelliferum 등 3종의 착편모조를 각각 먹이로서 급이 하면서 각각의 먹이에 따른 해산 요각류 T. japonicus의 nauplius 및 copepodid 유생의 개체수 증식 양상과 재포란 암컷의 개체수 변화 양상, 그리고 배양 도중 사망한 성체 암컷의 개체수를 서로 비교하였으며, 또한 각 계수일에 측정한 배 양수내의 먹이로서 급이한 3종의 착편모조의 세포수 변화 양상을 관찰하였다. 비교구로서 먹이를 전혀 공급하지 않은 실험구의 T. japonicus는 고압 멸균한 자연 해수만을 이용하여 배양하였다. 실험 결과 3종의 착편모조 중 I. galbana를 급이한 경우에는 T. japonicus의 정상적인 유생 발생과 함께 적극적인 I. galbana의 섭이를 관찰할 수 있었으나, P. parvum과 P. patelliferum을 급이한 경우에는 갓 부화한 nauplius 유생이 거의 100% 사망하였고 암컷 성체의 재포란율 또한 거의 0 (zero)임이 관찰되었다. 더욱이 15일간의 실험기간 중에 암컷 성체의 사망을 관찰하였다. 위와 같은 일련의 실험 결과로 볼 때, 독성을 가지며 적조의 원인종으로 알려진 착편모조 P. parvum과 P. patelliferum은 요각류 T. japonicus에 대해서 유해함을 알 수 있었다.

• ALGAE
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• 제37권2호
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• pp.175-183
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• 2022

Polar microorganisms produce physiologically active substances to adapt to harsh environments, and these substances can be used as biomedical compounds. The green microalga Micractinium variabile KSF0031, which was isolated from Antarctica, produced phytol, a natural antimicrobial agent. Furthermore, several polyunsaturated fatty acids (PUFAs), including omega-3, exhibit antioxidant properties. Here statistical methods (Plackett-Burman design and Box-Behnken design) were used to optimize the culture medium of KSF0031 to improve biomass production, and K₂HPO₄, MgSO₄·7H ₂O, and ammonium ferric citrate green (AFCg) were selected as significant components of the culture medium. Changes in the concentration of K₂HPO₄ and MgSO₄·7H ₂O as positive factors and AFCg as a negative factor affected cell growth to a remarkable degree. The biomass production in a 100 L culture using the optimized medium for 24 d at 18℃ was improved by 37.5% compared to that obtained using the original BG-11 medium. The quantities of PUFAs and phytol obtained were 13 mg g^-1 dry cell weight (DCW) and 10.98 mg g^-1 DCW, which represent improved yields of 11.70% and 48.78%, respectively. The results of this study could contribute to an improved production of phytol and fatty acids from Antarctic microalgae in the biomedical industry.

• 전기전자학회논문지
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• 제22권1호
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• pp.93-97
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• 2018

본 논문에서는 자동화 시스템을 이용하여 지속적으로 녹조를 제거하고 워터펌프를 이용하여 산소를 물속에 주입하여 녹조 생성이 잘 이루어지지 않도록 하는 시스템을 개발하였다. 제안한 녹조제거 자동화 시스템은 기계에 부착된 MCU(micro processor unit)를 이용하여 GPS와 초음파센서, 카메라등을 제어함으로 자동조정운행을 할 수 있고, 컨베이어 벨트, 워터 펌프등을 이용하여 녹조를 자동으로 제거할 수 있다. 또한 스마트폰의 어플리케이션과 연동하여 녹조제거 자동화 시스템의 위치를 추적하고 상황에 따라 사용자가 시스템을 직접 운영 할 수 있도록 하였다.

• ALGAE
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• 제28권1호
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• pp.93-99
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• 2013

A freshwater cyanobacterium, Phormidium autumnale KNUA026, was isolated from puddles of icy water in Gyeongsan City, South Korea and its potential as a biofuel feedstock was investigated. Maximal growth was obtained when the culture was incubated at $25^{\circ}C$ and around pH 9.0. The total lipid content of the isolate was approximately 14.0% of dry weight and it was found that strain KNUA026 was able to autotrophically synthesize heptadecane ($C_{17}H_{36}$) which can be directly used as fuel without requiring a transesterification step. As this benthic cyanobacterium was capable of forming thick mats, it could be easily harvested by gravitational settling and this property may reduce the cost of production in commercial applications. Hence, P. autumnale KNUA026 appears to be a promising resource for use in the production of microalgae-based biofuels.

• 동력기계공학회지
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• 제19권2호
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• pp.84-89
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• 2015

The occurrence of algae caused by eutrophication of fresh water is a pollution source to destroy the aquatic environment. When the high voltage electric field is applied in the water, When a high voltage is applied to the electric field in the water, the algae can be broken the balance of cell membranes, and is dead. In this paper, we develop a water quality improvement system for generating an electric field having a higher energy than the zeta potential when a high voltage is applied to 4,000V. To ensure the mobility of the water quality improvement system, we designed the PV generation system using the optimal size technique that is based on the model of power lack ratio. By evaluating the output characteristics of the water quality improvement system, power generation characteristics of the PV generation system, and battery charging characteristics, we can show that the proposed system can be applicable to the water quality improvement system inhibiting the growth rate of the algae in the fresh water.

• ALGAE
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• 제26권1호
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• pp.3-20
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• 2011

The physiology of the unicellular green alga Dunaliella salina in response to abiotic stress has been studied for several decades. Early D. salina research focused on its remarkable salinity tolerance and ability, upon exposure to various abiotic stresses, to accumulate high concentrations of $\beta$-carotene and other carotenoid pigments valued highly as nutraceuticals. The simple life cycle and growth requirements of D. salina make this organism one of the large-scale commercially exploited microalgae for natural carotenoids. Recent advances in genomics and proteomics now allow investigation of abiotic stress responses at the molecular level. Detailed knowledge of isoprenoid biosynthesis mechanisms and the development of molecular tools and techniques for D. salina will allow the improvement of physiological characteristics of algal strains and the use of transgenic algae in bioreactors. Here we review D. salina isoprenoid and carotenoid biosynthesis regulation, and also the biotechnological and genetic transformation procedures developed for this alga that set the stage for its future use as a production system.

• ALGAE
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• 제27권3호
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• pp.197-203
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• 2012

A eukaryotic microalga, Asterarcys quadricellulare KNUA020, was isolated from garden soil at Kyungpook National University in Daegu, South Korea and its biotechnological potential was assessed. Optimal growth was obtained when the culture was incubated at $25^{\circ}C$ and around pH 7.0. The total lipid content of the isolate was 15.5% of dry weight and its most abundant fatty acid was nutritionally important C18:3 ${\omega}3$ (${\alpha}$-linolenic acid, ALA). In addition, a high-value fatty alcohol, hexadecenol ($C_{20}H_{40}O$), was also identified in this photosynthetic microorganism. Hence, A. quadricellulare KNUA020 appears to be promising for use in the production of microalgae-based biochemicals.