• ALGAE
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• 제17권2호
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• pp.117-125
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• 2002

Five microalgal species isolated from the Jeju coast and four microalgal stock strains in hatchery were cultured in order to investigate their adapation to extreme changes in environmental factors such as salinity, water temperatue, adn nutrients. In case of salinity variation, Nitzschia sp. of Bacillariophyceae, Isochrysis galbana of Haptophyceae and Tetraselmis gracilis of Prasinophyceae showed optimum growth at the low salinity of 20 and 25 psu. Amphora coffeaeformis and Chetoceros simplex of Bacillariophyceae, and Pavlova lutheri of Haptophyceae adapted well at the relatively high salinities of 30 and 35 psu. However Phaeodactylum tricornutum of Bacillariophyceae and Chlorella sp. of Chlorophyceae showed euryhaline property In case of water temperature variation, most of all the species studied wer inhibited at 10℃. C. simplex, Nitzschia sp., p. tricornutum, Chlorella sp. and T. gracilis grew well at above 20℃. A. coffeaeformis, I. galbana and P. lutheri adapted also at the high temperature of 30℃. Each microalgal strain showed different growth rates and its maximum biomass. Generally microalgal populations from the Jeju coast grow well in relatively high salinity and high water temperature. Their growth were inhibited at low water temperature, but not likely affected at low salinity. This study indicates that the microalgal populations could not be affected by abnormally low salinity phenomena, which have happened occasionally around the west Jeju coast in summer and have led macrobenthic animals to mass mortality.

• 한국수산과학회지
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• 제40권1호
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• pp.8-15
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• 2007

This study selected the optimal microalgal species for mass culture of a brackish water copepod Paracyclopina nana. Fifteen microalgal species were tested to examine nauplius production and the survival and maturation of brood females. Total and daily nauplius production were highest in P. nana fed Tetraselmis suecica followed Isochrysis galbana, Dunaliella tertiolecta, and Phaeodactylum tricornutum. With a monospecific microalgal diet, the total density was highest with P. nana fed I. galbana, at 63.3 inds./mL. With a mixed microalgal diet, the total density of P. nana fed T. suecica+I. galbana was higher than that fed other mixed diets, although there was no difference between a monospecific diet of I. galbana and a mixed diet of T. suecica+I. galbana. Examining the fatty acid composition of P. nana, the eicosapentaenoic acid (EPA) was highest in P. nana fed T. suecica at 5.4% while the docosahexaenoic acid (DHA) content was highest I. galbana diet at 31.9%. Although no DHA was detected in T. suecica, P. nana fed this microalgal species had a high DHA composition of 24.3%. We suggest that the optimal microalgal species for the mass culture of P. nana is T. suecica which is easy to culture on masse and has a high linolenic acid content.

• Fisheries and Aquatic Sciences
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• 제14권4호
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• pp.339-345
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• 2011

Although culture techniques for the abalone Haliotis discus hannai are well known, mass culture of the benthic microalgae that are essential live food for the abalone larvae is still not practiced. This study was conducted to identify the microalgal species suitable for the growth of early larvae of H. discus hannai. The growth and attachment rates of 31 microalgal species were examined. Acrylic plates were used as the substrate. Among the 31 microalgal species, nine showing high growth and attachment rates were selected and tested for their dietary values via factors including settlement, metamorphosis, and survival rates of abalone larvae. Tetraselmis hazeni and Rhaphoneis sp. induced the highest settlement rate (65-69%) in abalone larvae. The metamorphosis rate was highest (57%) in larvae fed Rhaphoneis sp. and was also significantly higher in larvae fed Oscillatoria splendida (29%) and T. hazeni (22%) than in those fed other species. The highest survival rate of the larvae during the 15 days after metamorphosis was 67% in those fed Rhaphoneis sp., followed by T. hazeni (42%) and O. splendida (35%). In conclusion, Rhaphoneis sp. is the most suitable diatom for use as a live food for the culture of early larvae of H. discus hannai. In addition, T. hazeni and O. splendida are also potential species to be further developed and utilized in larval culture.

• Journal of Microbiology and Biotechnology
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• 제25권5호
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• pp.637-647
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• 2015

In this study, we attempted to understand signaling pathways behind lipid biosynthesis by employing a chemical genetics approach based on small molecule inhibitors. Specific signaling inhibitors of MAP kinase or modulators of cAMP signaling were selected to evaluate the functional roles of each of the key signaling pathways in three different microalgal species: Chlamydomonas reinhardtii, Chlorella vulgaris, and Haematococcus pluvialis. Our results clearly indicate that cAMP signaling pathways are indeed positively associated with microalgal lipid biosynthesis. In contrast, MAP kinase pathways in three microalgal species are all negatively implicated in both lipid and carotenoid biosynthesis.

• 환경생물
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• 제31권2호
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• pp.61-68
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• 2013

Microalgae can grow autotrophically with the supply of light, carbon dioxide and inorganic nutrients in water through photosynthesis. Generally, microalgal growth is limited by the concentrations and relative ratio of nitrogen (N) and phosphorus (P) among the nutrients in the aquatic environment. Each microalga has its specific optimum N : P ratio resulting in dominance in a particular water having similar nutrient composition. Algal bloom is an immense growth of certain microalga commonly cyanobacterium and can be sequestrated by reducing the limiting nutrient, generally P in the freshwater. Moreover, dominance of a less toxic blooming strain can be established by manipulating N : P ratio in the water. On the other hand, microalgal biomass of a certain species can be enhanced by increasing limiting nutrient and adjusting the N : P ratio to the target species. The above-mentioned eco-physiological features of microalgae can be more completely interpreted in connection with their genomic informations. Consequently, microalgal growth regulation which can be achieved on the basis of its eco-physiological and further genomic insights would be helpful not only in the control of algal bloom, but also for an increased yield of algal biomass.

• 한국패류학회지
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• 제27권2호
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• pp.143-148
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• 2011

연구는 양질의 피조개 수정란 확보와 안정적 종묘생산을 위하여 피조개 모패의 먹이생물로 미세조류 3종 (Isochrysis galbana, Tetraselmis tetrathele, Phaeodactylum tricornutum) 을 단독 또는 혼합 공급하여 먹이생물에 따른 피조개 모패의 비만도, 생식소발달, 성숙유도율 및 생존율을 조사하였다. 사육 45일 경과 후 피조개 모패의 완숙기 출현율, 성숙유도율 및 생존율은 3종의 미세조류를 혼합 공급하거나 T. tetrathele를 단독공급한 실험구에서 가장 높았다.

• 한국패류학회지
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• 제28권4호
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• pp.293-303
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• 2012

I. galbana, P. lutheri 및 C. simplex 3종을 먹이로 공급하며, 미세조류 종류에 따른 피조개 유생과 부착치패의 성장과 생존율 등을 비교하였다. 서로 다른 미세조류 3종을 단일 또는 혼합하여 먹이로 공급한 피조개 유생의 성장은 혼합 공급구에서 가장 빠르게 나타내었고, 단일 공급구 중에서 C. simplex 공급구에서 가장 높은 성장을 보였다. 또 유생의 생존율은 혼합 공급구에서 $27.4{\pm}5.3%$로 가장 높게 나타내었고, 단일 공급구 중에서 C. simplex 공급구에서 $14.5{\pm}2.3%$로 가장 높았다. I. galbana, P. lutheri, C. simplex 3종을 단일 또는 동일비율로 혼합한 미세조류의 지방산 조성은 EPA의 경우 C. simplex에서만 $25.9{\pm}0.64%$로 나타났고, 다불포화지방산(PUFA)과 n-3 HUFA 함량은 C. simplex에서 가장 높게 나타났다. 또 이들 미세조류를 먹이로 공급한 피조개 부착치패의 경우 C. simplex 공급구에서 포화지방산과 AA 함량이 유의하게 높았다. 이와 같은 C. simplex의 지방산 조성이 피조개 유생과 부착치패의 성장과 생존율의 원인으로 판단된다. 따라서 단일종으로는 C. simplex가 가장 적합하나 3종을 혼합하여 공급하는 것이 더 좋은 먹이효율을 유도할 수 있다.

• 한국환경과학회지
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• 제12권7호
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• pp.715-724
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• 2003

Distributional patterns of microalgae were studied in the tidal flats of Gamami Beach(Young-Gwang, Korea) from November 1999 to 2000 July. The tidal flats of Gamami Beach was composed mainly of sandy sediment. The concentrations of nutrients were low compared with other tidal flats. In the present study, 68 species of microalgal flora were identified. These were comprised of 25 species of benthic microalgae and 59 species of planktonic microalgae. Diatoms predominated the benthic microalgae with 96.0% of total species occurred. Dominant species were Amphora sp., Cocconeis sp., Coscinodiscus asteromphalus, Coscinodiscus sp., Nitzschia sigma var. intermedia, Nitzschia distans, Navicula spp., Paralia sulcata, Pleurosigma sp. Skeletonema coastatum, and Surirella sp. Among them, Amphora sp., Paralia sulcata, and species of Pleurosigma and Nitzschia were observed throughout the studied period. Planktonic microalgae of Gamami Beach was also predominated by diatoms. They occupied 88.1% of total planktonic microalgae. The density of microalgal population was higher in silty sediment than in sandy sediment. The population density of microalgae was higher in high tide zone than that in low tide zone. The density of the benthic microalgae in the surface layer of tidal flats showed increasing tendency for 2 hours after the beginning of ebb tide. On the contrary, benthic microalgal density of subsurface layer was decreased during the period. Concentrations of chlorophyll ${\alpha}$ from sediment and water were not synchronized during the study period. Therefore, the distributional patterns of the benthic microalgae and planktonic algae seemed not to be related. Chlorophyll ${\alpha}$ of water was highly related with the concentration of NH$_4$-N, whereas, chlorophyll ${\alpha}$ of sediment uas related with NO$_3$-N concentration.

• 한국수산과학회지
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• 제42권3호
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• pp.268-275
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• 2009

The survival and growth of marine benthic invertebrate larvae such as abalone depend on the nutritional value of micro algae. However, it is difficult to determine the dietary value of the many microalgal species used for food by benthic larvae. Therefore, we tested the benthic copepod, Tigriopus japonicus, which grazes microalgae on substrata in a manner similar to abalone larvae. It also has short generation time and is easy to rear which makes to be easier to examine the dietary value of each micro algal species. We measured the daily production of nauplii from gravid females of T. japonicus fed 26 microalgal species separately. Amino acid and fatty acid content of the micro algae and the copepod was also analyzed. The nauplii production of T. japonicus was the highest (10.7) when they were fed Navicula sp. (B-394) and the lowest (0.8) when they were fed Scrippsiella trochoidea. In Tetraselmis suecica the nauplii production was so high (8.2), which was not significantly different with the diatom group. We determined that Navicula sp. (B-394), Rhaphoneis sp. and T. suecica were good sources of food for T. japonicus. We suggest that a diet of with a mixture of these three micro algal species may be also good for invertebrate larvae such as abalone.

• Fisheries and Aquatic Sciences
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• 제14권4호
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• pp.323-332
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• 2011

To find seasonally optimal microalgae for mass culture of the rotifer Brachionus plicatilis, the growth rates of 12 microalgal species (two marine Chlorella spp., five marine Nannochloris spp., two marine Nannochloropsis spp., one estuarine Nannochloropsis sp., and two estuarine Chlorella spp.) were compared at $25^{\circ}C$ at 15 psu and 30 psu. Among these, six species showing high growth rates were chosen and examined again at high ($30^{\circ}C$ and $32^{\circ}C$) and low ($10^{\circ}C$) temperatures. Their amino and fatty acids and the dietary value of the rotifers that fed on each microalgal species were examined. Nannochloris sp. (KMMCC-119) and Chlorella vulgaris (KMMCC-120) showed the highest growth rates at temperatures over $30^{\circ}C$ and at $10^{\circ}C$, respectively. The growth rate of Nannochloris was higher than those of Chlorella and Nannochloropsis at high temperatures, but lower than those of the latter at low temperatures. The growth rate of rotifers fed on Nannochloropsis was highest and that of those fed on Chlorella was lowest. Levels of eicosapentaenoic acid and docosahexaenoic acid were highest in Nannochloropsis and lowest in Nannochloris. However, total amino acid content was highest in Nannochloris and lowest in Chlorella. In conclusion, Nannochloropsis sp. (KMMCC-33) was the best microalgal species for the mass culture of the rotifer. However, during high- or low-temperature seasons in which Nannochloropsis does not grow well, Nannochloris spp. (KMMCC-119, 395) and C. vulgaris (KMMCC-120) would adequately replace Nannochloropsis sp. (KMMCC-33).