• KSBB Journal
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• v.26 no.3
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• pp.206-210
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• 2011

The growth effect of Nannochloropsis oculata (N.oculata), unicellular microalgae, by alginate was investigated. Alginate was depolymerized with sulfuric acid ($H_2SO_4$) and heat ($121^{\circ}C$), simultaneously. Addition of 0.75% alginate oligomer depolymerized with 0.2 N $H_2SO_4$ showed the maximum yield and the growth rate of N. oculata. Chlorophyll content and reducing sugar was increased by alginate oligomer in a dose-dependent manner. Alginate oligomer promoted the growth of N. oculata, whereas the original alginate polysaccharides had no significant effect. Laminaria japonica (L. japonica) extract containing high level of alginate was also increased growth rate and chlorophyll content. $CO_2$ supply addition to L. japonica extract showed no change the growth rate, although addition to alginate oligomer showed prominently increased. N. oculata could use more saccharides in presence of $CO_2$ according to reducing sugar determination. From these results, it is useful to establish optimal condition for high cell density cultivation of N. oculata.

• Applied Chemistry for Engineering
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• v.25 no.3
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• pp.324-329
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• 2014

Microalgae Nannochloropsis oculata (N. oculta) and Chlorella vulgaris (C. vulgaris) are important sources for biodisel because of the high content of neutral lipids. Stable nano bubble is maintained for a long time and therefore it is possible for use in biotechnology. In this study, effects of nano bubble oxygen or hydrogen water on the microalgae growth were characterized. The cell growth in nano bubble water was similar to that of control, and the total lipid content was rather low. But, chlorophyll content of N. oculata grown in nanno bubble oxygen and hydrogen water increased 54% and 30%, and increased 59%, 39% in C. vulgaris. Carotenoid content also increased 21%, 25% in N. oculata and 49%, 29% in C. vulgaris grown in nano bubble oxygen and hydrogen water. From these results, nano bubble water seems to enhance the photosynthetic capacity of microalgae.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.3
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• pp.260-267
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• 2001

The biochemical composition and antioxidative activity of marine microalgae were investigated for the effective utilization of marine resources. Two species of marine microalgae, Nannochloris oculata (N. oculata) of Chlorophyceae and Phaeodactylum tricornutum (P. tricornutum) of Bacillariophyceae, were selected. Because these species showed the high growth rate and easy to continuous culture. The contents of crude protein, lipid, and carbohydrate were $54.91\%,\;11.29\%,\;and\;10.15\%$, for N. oculata and $38.07\%,\;13.19\%,\;and\;7.13\%$, for P. tricornutum, respectively. Glutamic acid was the highest concentration for both species. Galactose (3,712.02 mg/100g), fucose (1,966.03 mg/100g), and glucose (1,814.35 mg/100g) were the major carbohydrates for N. oculatae, and glucose (5,295.45 mg/100g) and mannose (841.34 mg/100g) were for P. tricornutum. K (12,906.86 mg/100g), Mg (1,039.15 mg/100g), Ca (882.57 mg/100g) and Fe (747.20 mg/100g) were the major minerals for N. oculata, and K (11,718.65 mg/100g), Ca (2,003.32 mg/100g), Mg (1,570.84 mg/100g) and Fe (552.58 mg/100g) were for P. tricornutum. In the composition of nucleotides, ADP ($4.77{\mu}mol/g$) was the highest in N. oculata and hypoxanthine (11.74{\mu}mol/g) in P. tricornutum. Large amount of linoleic acid (18: 2, $\omega-6$) was contained in N. oculata. In contrast 16: 1 ($\omega-7$) and 20: 5 ($\omega-3$) were major fatty acid in P. tricornutum. The antioxidative activities of organic solvent extracts of two microalgae were measured by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay method. The chloroform extract obtained from P. tricornutum was identified to be the most effective in DPPH radical scavenging activity.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.3
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• pp.252-258
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• 2013

The quality and quantity of food organisms in fish seed production are important. The marine microalgae Nannochloropsis oculata are used as initial food organisms in the field. We investigated the effects of salinity (0, 10, 20, 30, 40 and 50 psu) on the lipid and fatty acid composition of N. oculata. Cultivation of N. oculata at varying salinities showed the highest growth rate at 20 psu. Total lipid content ranged from 17.26 to 18.63% at salinities from 0 to 50 psu). The nonpolar lipid content increased markedly at 30 psu and was highest at 15.55%. The polar lipid content was lowest at 30 psu, by 84.45%. It was also found that the omega-3 and EPA contents were inversely proportional to salt concentration. For the polar and nonpolar lipid compositions, there was no significant effect of salinity. Omega-3 polyunsaturated fatty acid content especially the content of EPA in the seawater larvae is the essential fatty acid in this food organism. It is thus advantageous to culture N. oculata at 20 psu.

• Journal of Marine Bioscience and Biotechnology
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• v.8 no.2
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• pp.45-53
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• 2016

Most of microalgae shift their metabolic pathways toward the fatty acid biosynthesis following nitrogen deprivation. Recent studies on Nannochloropsis species, oleaginous microalgae, have been performed to investigate the regulation of contents and compositions of fatty acids under stressful condition. The objective of this experiment is to identify the effect of nitrogen on cell growth and fatty acids production in Nannochloropsis oculata K-1281 and compare fatty acid composition response to nitrogen deficiency between N. oculata LB2164 and K-1281. The fatty acids content in N. oculata K-1281 was increased up to 210%, while the growth rate was decreased under nitrogen deficient condition. The contents of C16:0 and C16:1 increased dramatically in both N. oculata K-1281 and LB2164, while the contents of C20:4 and C20:5 increased in N. oculata LB2164. The fatty acids content and composition in N. oculata K-1281 returned following addition of nitrogen after nitrogen starvation. These results demonstrated that fatty acid contents and compositions under nitrogen deficiency will provide the understanding of fatty acid synthesis in microalgae.

• Fisheries and Aquatic Sciences
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• v.8 no.4
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• pp.201-206
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• 2005

Microalgae are widely used for mass culture of the rotifer Brachionus plicatilis in aquaculture. Since the nutritional value of the rotifer is closely related to its food, the nutritional value of its food should be known in detail. Chlorella ellipsoidea and Nannochloris oculata are re­presentative food organisms for rotifers that are easily cultured. Therefore, the nutritional values of these micro algae were examined for ultrasmall, small, and large rotifers and Artemia nauplii. Chlorella ellipsoidea contained seven times more total fatty acids than N. oculata. The three types of rotifer fed N. oculata contained more amino acids than those fed C. ellipsoidea. However, the total fatty acids of the rotifers fed each microalga species differed according to the type of rotifer. Newly hatched Artemia nauplii contained more protein and had a higher dry weight than those fed microalgae for 6 h. As with the rotifers, the Artemia nauplii fed N. oculata contained more protein and amino acids than those fed C. ellipsoidea, while the reverse was true for the total fatty acid content. Our results suggest that N. oculata is a good supply of protein, while C. ellipsoidea is a good source of lipids as food organisms for rotifers and Artemia nauplii in aquaculture.

• KSBB Journal
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• v.25 no.6
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• pp.553-558
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• 2010

Increasing demands on fossil fuel have led to the unprecedented attraction to microalgal biofuel as an alternative energy. In this study, we investigated growth and lipid productions of microalga Nannochloris oculata under various carbon dioxide or nitrogen source concentrations and irradiance conditions. Biomass production of N. oculata was highest under 2% $CO_2$ with 0.3 flow rate (vvm). In addition, biomass productivities were proportional to the concentration of nitrogen source, whereas lipid biosynthesis was suppressed under higher nitrogen concentration (up to 50 mg/L). High irradiation ($160{\sim}180\;{\mu}mol/m^2{\cdot}s$) enhanced growth rate and lipid production of N. oculata.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.5
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• pp.437-444
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• 2010

Extracts of the marine microalgae Nannochloropsis oculata were obtained using 80% methanol (MeOH) and water. The 80% MeOH extract was further fractionated with n-hexane, chloroform, ethyl acetate (EtOAc), n-butanol (n-BuOH), and water to isolate the active fraction. Seven samples were prepared and their angiotensin converting enzyme (ACE), $\alpha$-glucosidase, and cancer cell growth inhibitory activities in vitro were determined. The most profound ACE inhibitory activity was observed in the chloroform fraction, while the others had moderate effects. By contrast, greater $\alpha$-glucosidase inhibitory activity was found in the EtOAc fraction, n-hexane fraction, and water extract of N. oculata. The antiproliferative effects of the extracts and fractions against HL-60, U937, CT-26, and SK-Hep1 cancer cells were also determined. The n-BuOH fraction had the strongest antiproliferative effects on CT-26 cells in a time-dependant manner (P<0.05). These results suggest that the extracts and fractions from N. oculata could be used as a potential functional food or as pharmaceutical ingredients.

• Applied Chemistry for Engineering
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• v.24 no.2
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• pp.155-160
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• 2013

Research on mutant generation and isolation for microalgae yielding enhanced lipid accumulation is an important issue for the production of economic biodiesel. In the present study, ultraviolet (UV-B type) ray induced mutant generation was tried using a photosynthetic microalgae, Nannochloropsis oculata (N. oculata), for the production of biodiesel. The resulting colonies were isolated and further cultured with both liquid and solid state f/2 media. After a few week cultivation, changes of cell growth rate, dry cell weight, and several important intracellular components (chlorophyll, carotenoid, and lipid) were investigated. Two mutants among thousands colonies showed an increased cell growth and high lipid accumulation as compared to those of wild type. It was also observed that the increased cell growth rate is associated with the overexpressed intracellular proteins. However, the mutants showed a decrease in the chlorophyll biosynthesis.

• Animal Systematics, Evolution and Diversity
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• v.23 no.2
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• pp.169-173
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• 2007

Two new marine sponges in the family Chalinidae, Haliclona (Haliclona) uljinensis n. sp. and Haliclona (Reniera) hongdoensis n. sp., are collected from Uljin and Hongdo Island, Korea during 2004-2007. H. (H.) uljinensis n. sp. is closely related to H. (H.) oculata in type of spicules. However, ectosomal skeleton of H. (H.) uljinensis n. sp. is reticulated and isodictyal reticulated type but H. (H.) oculata has not any dermal specialization in skeleton. The growth form of H. (H.) uljinensis n. sp. is thin encrusting with numerous cylindrical tubes on the surface but H. (H.) oculata is solid branch form. Haliclona (R.) hongdoensis n. sp. is closely related to H. (R.) aquaeductus in skeletal structure and growth form. However, oxeas of H. (R.) hongdoensis n. sp. are larger than H. (R.) aquaeductus's.