• Fisheries and Aquatic Sciences
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• v.14 no.4
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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).

• Journal of Microbiology and Biotechnology
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• v.18 no.12
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• pp.1919-1926
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• 2008

Statistical experimental designs; involving (i) a fractional factorial design (FFD) and (ii) a central composite design (CCD) were applied to optimize the culture medium constituents for production of a unique antifreeze protein by the Antartic micro algae Chaetoceros neogracile. The results of the FFD suggested that NaCl, KCl, $MgCl_2$, and ${Na}_{2}{SiO}_{3}$ were significant variables that highly influenced the growth rate and biomass production. The optimum culture medium for the production of an antifreeze protein from C. neogracile was found to be Kalle's artificial seawater, pH of $7.0{\pm}0.5$, consisting of 28.566 g/l of NaCl, 3.887 g/l of $MgCl_2$, 1.787 g/l of $MgSO_4$, 1.308 g/l of $CaSO_4$, 0.832 g/l of ${K_2}{SO_4}$, 0.124 g/l of $CaCO_3$, 0.103 g/l of KBr, 0.0288 g/l of $SrSO_4$, and 0.0282 g/l of ${H_3}{BO_3}$. The antifreeze activity significantly increased after cells were treated with cold shock (at $-5^{\circ}C$) for 14 h. To the best of our knowledge, this is the first report demonstrating an antifreeze-like protein of C. neogracile.

• The Plant Pathology Journal
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• v.20 no.2
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• pp.158-163
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• 2004

Chlorella is a eukaryotic microalgae which shares metabolic pathways with higher plants. These charac-teristics make chlorella a potential candidate for eukaryotic overexpression systems. Recently, a foreign flounder growth hormone gene was stably introduced and expressed in transformed Chlorella ellipsoidea by using a modified plant transformation vector that contains cauliflower mosaic virus (CaMV) 35S pro-moter and the phleomycin resistant Sh ble gene as a selection marker. In this study, this same vector was modified by incorporating a promoter and a 3' UTR region of the 33kDa peptide gene from a chlorella virus that was isolated in our laboratory. The 33kDa gene promoter was used to replace the 35S promoter and the 3' UTR was introduced to separate the target gene and downstream Sh ble gene. Three different chlorella transformation vectors containing human erythropoietin (EPO) gene were constructed. The mp335EPO vector consists of a promoter from the 33kDa peptide gene, whereas the mp3353EPO vector contains the same promoter from the 33kDa peptide gene and its 3' UTR. The mp35S33pEPO vector contains the 35S promoter and the 3' UTR from the 33 kDa peptide gene. There was no significant difference in the expression levels of EPO protein in chlorella cells transformed with either of three of the transformation vectors. These data indicate that the promoters from the chlorella virus are comparable to the most common CaMV 35S promoter. Furthermore, these data suggest that other promoters from this virus can be used in future construction of chlorella transformation system for higher expression of target proteins.

• Journal of Korean Society of Water and Wastewater
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• v.28 no.6
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• pp.691-698
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• 2014

This study investigated the effect of a co-culture of Scenedesmus dimorphus and nitrifiers using artificial wastewater on the removal of ammonium, nitrate and phosphate in the advanced treatment. To test the synergistic effect of the co-culture, we compared the co-culture treatment with the cultures using S. dimorphus-only and nitrifiers-only treatment as controls. After 6 days of incubation, nitrate was removed only in the co-culture treatment and total amount of N removal was 1.3 times and 1.6 times higher in the co-culture treatment compared to those in the S. dimorphus- and nitrifiers-only treatments, respectively. In case of total amount of P, co-culture treatment removed 1.2 times and 12 times more P than the S. dimorphus -and nitrifiers-only conditions, respectively. This indicates that the co-culture improved removal rates for ammonium, nitrate, and phosphate. This further implies that there was no need for denitrification of nitrate and luxury uptake of P processes because nitrate and phosphate can be removed from the uptake by S. dimorphus. In addition, co-culture condition maintained high DO above 7 mg/L without artificial aeration, which is enough for nitrification, implying that co-culture has a potential to decrease or remove aeration cost in the wastewater treatment plants.

• Korean Journal of Environmental Biology
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• v.38 no.3
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• pp.424-432
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• 2020

The present study aimed to analyze the metaproteome of the microbial community comprising harmful algal bloom (HAB) in the Daechung reservoir, Korea. HAB samples located at GPS coordinates of 36°29'N latitude and 127°28'E longitude were harvested in October 2013. Microscopic observation of the HAB samples revealed red signals that were presumably caused by the autofluorescence of chlorophyll and phycocyanin in viable cyanobacteria. Metaproteomic analysis was performed by a gelbased shotgun proteomic method. Protein identification was conducted through a two-step analysis including a forward search strategy (FSS) (random search with the National Center for Biotechnology Information (NCBI), Cyanobase, and Phytozome), and a subsequent reverse search strategy (RSS) (additional Cyanobase search with a decoy database). The total number of proteins identified by the two-step analysis (FSS and RSS) was 1.8-fold higher than that by one-step analysis (FSS only). A total of 194 proteins were assigned to 12 cyanobacterial species (99 mol%) and one green algae species (1 mol%). Among the species identified, the toxic microcystin-producing Microcystis aeruginosa NIES-843 (62.3%) species was the most dominant. The largest functional category was proteins belonging to the energy category (39%), followed by metabolism (15%), and translation (12%). This study will be a good reference for monitoring ecological variations at the meta-protein level of aquatic microalgae for understanding HAB.

• Journal of Life Science
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• v.14 no.4
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• pp.593-607
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• 2004

The nucleotide sequence for a nuclear-encoded small subunit rDNA (SSU rDNA) was determined for 43 species of the class Dinophyceae, including harmful algae Cochlodinium polykrikoides and Gyrodinium aureolum. These sequences and data analyses were performed by parsimony, distances and maximum likelihood methods in PHYLIP (Phylogenetic Inference Package) version 3.573c. The species Noctiluca scintillans, Gonyaulax spinifern and Crypthecodinium cohnii occupied a basal position within the Dino- phyceae in our analyses. The genera Alexandrium and Symbiodinium were monophyletic (supported by a bootstrap value of >70%), whereas the genera Gymnedinium and Gyrodinium formed polyphyletic nodes, for which bootstrap support was strong (>70%) in the neighbor-joining and maximum likelihood methods except for the PHYLIP parsimony analysis (=59%). The sequence divergence between G. aureolum and G. dorsum/ G. galathenum was the largest at 7.4% (45 bp), whereas G. aureolum and G. mikimotoi showed an extremely low value of genetic divergence of 0.9% (5 bp). The genetic divergence between C. polykrikoides and G. aureolum was a low value of 5.2% (31 bp). In the phylogenetic analysis, the placement of G. aureolum and C. polykrikoides was closer to the genus Gymnodinium than to the genus Gyrodinium, which was supported by a moderate bootstrap value.

• Journal of Life Science
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• v.14 no.4
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• pp.589-592
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• 2004

The growth response of the fish-killing dinoflagellate Cochlodinium polykrikoides was studied in cultures, using the treatment of Ceratium extracts by a methanol, a water-soluble, and a cell-free medium. The cell-free medium had the most increasing on the growth of C. polykrikoides cultures, enriched with $\geq$ 25% Ceratium, whereas the methanol and water-souble fractions did not affect the growth of C. polykrikoides exposed to even higher concentration. In particular, the cell-free medium also increased the growth of Gyrodinium impudicum and Chaetoceros sp., similar species to C. polykrikoides. In contrast to C. polykrikoides, G. impudicum and Chaetoceros sp., the growth of Alexandrium tamarense was inhibited significantly, and there was no great effect on the growth of Prorocentrum minimum. These results imply that Ceratium extracts may play an important role in the stimulatory effect of C. polykrikoides, and they have to affect the interaction between C. polykrikoides and Ceratium when co-existing.

• Korean Journal of Ecology and Environment
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• v.35 no.2 s.98
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• pp.133-140
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• 2002

This study was performed in lab scaled oxidation pond. The removal efficiency of pollutant on the influence of changes of hydraulic retention time and pond style was investigated. The correlation between organic removal efficiency and dissolved oxygen concentration on algal photosynthesis showed the light time revealed a higher relationship more than the dark time, and the squares of the correlation coefficient of 15 days retention time were higher than that of 5 days in single pond. The variation of dissolved oxygen concentration of a series pond was from 4.2 to 19.8 mg/l under 5 days retention time, the concentration of dissolved oxygen increased with increasing step of series pond. Between the single pond and a series of pond system, a series of pond system showed better organic removal efficiency. Average removal efficiency range of $TBOD_5$ and $SBOD_5$ was $49{\sim}83%$ and $87{\sim}92%$, respectively. Algae should be removed appropriately to increase the removal efficiency of organic matter.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.3
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• pp.259-265
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• 2013

The marine microalgae Nannochloropsis sp. was cultured under a metal halide lamp (MH) or light-emitting diodes (LEDs) of various wavelengths (blue, LB; red, LR; yellow, LY; green, LG; white, LW); changes in growth, total carotenoid, chlorophyll a, amino acid and fatty acid profiles were investigated. LB-exposed cultures exhibited the highest specific growth rate (SGR) (0.32), whereas LY-exposed cultures showed the lowest SGR (0.18). After cultivation for 9 days, the maximum dry cell weight (g/L) of LB-exposed cultures was significantly higher than that of those exposed to other light conditions (LB>MH>LW$${\geq_-}LG{\geq_-}$$LR>LY). The essential amino acid (EAA, %) contents of cultures exposed to LG, LB, LR and MH were higher than those exposed to LY and LW (P<0.05). Eicosapentaenoic acid and n-3 highly unsaturated fatty acid levels were significantly higher in MH-exposed cultures compared to those exposed to LY (P<0.05), with no marked difference compared to those exposed to LB, LG, LR and LW (P>0.05). The total carotenoid content was highest in LR-exposed cultures (18.0 mg/L), whereas MH showed the lowest (11.8 mg/L; P<0.05). Chlorophyll a content was highest in cultures exposed to LR compared to other light sources. These results suggest consistent differences in growth and biochemical composition after exposure to light of different wavelengths.

• KSBB Journal
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• v.14 no.4
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• pp.414-421
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• 1999

The influenced of light intensity, cell density, and light pathlength on photosynthetic activity of Chlorella vulgaris were investigated. Since the light respon curve varied according to reaction conditions, the parameters estimated from nonlinear regression were proved to be apparent and could not be applied to various situations. The light response model incorporating the light penetration through the microalgal suspension was developed based upon the spatial distribution of the photosynthetic activity. This model showed a good agreement with experimental data at different cell densities and light intensities. Using the model the effects of cell density and light pathlenth were simulated and some dicussions about optimization of operation conditions of photobioreactors were carried out. Concludingly, the developed model can be useful for predicting microalgal photosynthesis and for determining the optimal operating conditions.