• Ocean and Polar Research
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• v.35 no.1
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• pp.39-50
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• 2013

Biomass and community composition of microphytobentos in tidal flats were studied by HPLC analysis and also investigated to examine the relationship between microphytobenthic pigments and Adenosine-5' triphosphate (ATP) as an index of total microbial biomass in intertidal environments (muddy and sandy sediment) of Gyeonggi Bay, west coast of Korea. Microphytobenthic pigments and ATP concentration in muddy sediment were the highest at the surface while the biomass of microphytobenthos in sandy sediment was the highest at the sub-surface (0.75 cm sediment depth). The detected pigments of microphytobenthos were chlorophyll a, b (euglenophytes), $c_3$, peridinin (dinoflagellates), fucoxanthin (diatom or chrysophytes), diadinoxanthin, alloxanthin (cryptophytes), diatoxanthin, zeaxanthin (cyanobacteria), ${\beta}$-carotein, and pheophytin a (the degraded product of chlorophyll a). Among the pigments which were detected, the concentration of fucoxanthin was the highest, indicating that diatoms dominated in the microphytobenthic community of the tidal flats. There was little significant correlation between OC (Organic Carbon) and ATP in both sediments. However, a positive correlation between chlorophyll a concentration and ATP concentration was found in sandy sediment, suggesting that microbial biomass could be affected by labile OC derived from microphytobenthos. These results provide information that may help us understand the relationship between microphytobenthos and microbial biomass in different intertidal sediment environments.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.40 no.1
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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.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.3
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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.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.12
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• pp.6208-6214
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• 2012

The most essential but missing components to understand and use toxic substances from marine microalgae are developing the fast, easy and economical determining technology for detecting it. In this paper we produced the antibodies against saxitoxin (STX). Mariculture keyhole limpet hemocyanin (mcKLH) and ovalbumin (OVA) were used as carrier proteins. mcKLH-STX conjugates were injected into the peritonial cavity of BALB/c mouse for immunization. After bleeding from mouse, anti-STX antiserum was isolated. Indirect enzyme-linked immunosorbent assays (ELISA) was performed to determine antiserum titer using the microtiter plate coated with free STX and OVA-STX. A goat anti-mouse IgG-phosphatase conjugate was used as secondary antibody to enable chromogenic reaction. Reactions of anti-STX antiserum were very specific on the OVA-STX and free STX. Sensitivity of anti-STX antiserum on STX was very high and STX detection limit was to be 64.9 ng/kg for indirect ELISA.

• Microbiology and Biotechnology Letters
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• v.48 no.3
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• pp.337-343
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• 2020

In this study, the medium optimization for cell growth and metabolite formation of Haematococcus sp. under mixotrophic cultivation was investigated. As a result, modified MS medium was selected as the basal medium; glucose was selected as the carbon source, with an optimum concentration of 10 g/l, and potassium nitrate was chosen as the nitrogen source, with an optimum concentration of 1.9 g/l. Under optimum conditions, Haematococcus sp. demonstrated an increase in biomass concentration from 0.18 gDW/l to 5.58 gDW/l in 14 days, after which there was a 31-fold increase in its growth. At the same time, the concentrations of chlorophyll and carotenoids were 172.16 mg/l and 42.33 mg/l, respectively. This work will contribute to the basic data for mass cultivation of microalgae.

• Korean Chemical Engineering Research
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• v.56 no.3
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• pp.376-380
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• 2018

The astaxanthin recovery efficiencies were compared in acetonitrile, acetone, methanol, dichloromethane : methanol (1:3, v/v) and ethylacetate : ethanol (1:1, v/v) as a extraction solvent after the grinding of the H. pluvialis cells. The astaxanthin extraction yield in acetone was 1.13~1.29 times higher than other extraction solvents. It was also found that 96.7% of astaxanthin accumulated in H. pluvialis could be recovered by a single extraction. Since astaxanthin exists mainly as astaxanthin esters in H. pluvialis, a gradient reversed-phase HPLC analysis was carried out for the separation of astaxanthin esters from the extracts of H. pluvialis. Among the astaxanthin inside the H. pluvialis cell, free astaxanthin was 45.9% and astaxanthin esters were the rest.

• Korean Journal of Pharmacognosy
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• v.31 no.2
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• pp.252-255
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• 2000

In order to screen new radical scavenging principle which is expected to be antiaging drug lead, we have investigated 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity of the marine microalgae, greenalgae(10 speices), diatom (10 speices) and blue-green algae (10 speices). The significant activities$(IC_{50}:\;<100\;{mu}g/ml)$ were observed in 4 species of green algae (MA002, 006, 009, 010), 1 species of diatom (MA015) and 5 species of blue-green algae (MA017, 018, 019, 024, 025). Within the scope of family tested, MA009 $(IC_{50}:\;=78\;{mu}g/ml)$, MA015 $(IC_{50}:\;=38\;{mu}g/ml)$ and MA019 $(IC_{50}:\;=41\;{mu}g/ml)$ displayed the most significant activity. Among the marine microalgae tested at family level, cyanophycean blue-green algae was shown to be the most active family on screening of new bioactive compounds.

• 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 Marine Bioscience and Biotechnology
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• v.9 no.1
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• pp.8-13
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• 2017

Cost-effective microalgae harvesting methods are necessary for economical production of algal biodiesel. In this study, membranes with various pore sizes and materials were examined for their potentials in application to gravity-filtration of Tetraselmis sp. KCTC12432BP. For this test, 10 L of Tetraselmis sp. culture (2 g/L) was loaded on each membrane and filtration rates were measured. Among the tested materials, a woven cotton fabric showed the fastest water drain rate (0.73 L/hr) without serious cell leakage. Cell density of the concentrates after filtration was 6.8 g/L, indicating 3.4-fold concentration compared with the initial algal culture. The result suggests that the woven cotton fabric could serve as filtration membrane for harvesting Tetraselmis sp. among the tested ones.

• Korean Journal of Environmental Agriculture
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• v.26 no.1
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• pp.7-16
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• 2007

The objective of this research was to review the correlation between microalgae and agricultural water quality. Although microalgae has been considered as an essential factor for control1ing of water ecosystem, little attention has been paid for evaluating of microalgae as an important factor for water quality management. But it can be use to make us know the water pollution state at saprobic system, LTSI (Lake Tropic State Index), DAIpo (Diatom Assemblage Index to Organic Pollution), and AGP (Algal growth potential). In saprobic system, it is used microalgae such as Actinastrum hantzschii var. fluviatile, Asterionella gracillima, Coelastrum microporum, Synedra acus, Dictyosphaerium pulchellum, Micractinium pusillum, Cyclotella meneghiniana, Microcystis aeruginosa, Scenedesmus quadricauda, and Nitzschia palea for assessment water quality. In addition, they have ecologically significant characteristics such as dominant species, cosmopolitan species, redtide causative species etc. Also, microalgae such as Botryococcus braunii, B. sp., Chlorella vulgaris, C. sp., Phormidium sp., Scenedesmus quadricauda, Selenastrum capricornutum, Spirulina maxima, and S. platensis have an effect on improvement of water quality.