• ALGAE
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• v.17 no.3
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• pp.171-185
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• 2002

The standing crop of genus Microcystis, microcystin concentrations and environmental factors were monitored at stations of the lower reaches of the Nakdong River in 1998 and 1999 during the periods of its occurrence. The Microcystis were observed from May to Octorber, and the cell density was highest at Station Seonam up to 250,000 cells${\cdot}ml^{-1}$ forming scum over the water surface. There were signigicant relationships between the standing crop of Microcystis and nitrate nitrogen, total phosphorus concentrations and Ph. Presumably these parameters were important in the succession to Microcystis dominated phytoplankton community in the summer period in the river. However, Ammonium nitrogen, phosphate phosphorus concentrations and N/P ratio were not critical factors. The Microcystis bloom was notable above $25^{\circ}C$ of surface water temperature. Microcystins were detected from May to November in the algal materials from the river. The 84.2% of algal materials with Microcystis exhibited the microcystin with the maximum of 1711.8 ${\mu}g{\cdot}g^{-1}$ dw. The microcystin concentrations in the algal materials were significantly related to the stading crop of Microcystis, which was the primary determinant factor in the toxin levle of algal materials. The concentrations were also significantly related to pH of the water column in the positive pattern.

• Journal of Environmental Science International
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• v.9 no.3
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• pp.267-273
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• 2000

In order to understand the impact for decomposition of blue-green algae Microcystis on water quality, the algae were cultivated with collection of natural population during approximately one month, when water-bloom of Microcystis dominated at August 31, 1999 in the lower part of the Okchon Stream. The enrichment of inorganic NㆍP nutrients didn't in algal assay and the effect of Microcystis on water duality was assessed from the variation of nutrients by algal senescence. Microcystis population seemed to play a temporary role of sink for nutrients in the water body. Initial algal density of Microcystis was 2.3×10/sup 6/ cells/㎖. When Microcystis population died out under light condition, algal NㆍP nutrients between 9∼12 days affected to increase of biomass after reuse by other algal growth as soon as release to the ambient water. However, cellular nutrients under dark condition were almost moved into the water during algal cultivation. NH₄, NO₃ and SRP concentration were highly increased with 160, 17 and 79 folds, respectively relative to the early. As a result, the senescence of Microcystis population seemed to be an important biological factor in which cause more eutrophy and increase of explosive algal development by a lot of nutrients transfer to water body. There are significantly observed an effort of reduce for production of inner organic matters such a phytoplankton as well as load pollutants from watershed in side of the water quality management of reservoir.

• Korean Journal of Environmental Biology
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• v.21 no.2
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• pp.216-221
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• 2003

Various physico-chemical and biological methods have been used to remove. cyanobacteria which causes blooms and releases toxin. The purpose of the following experiment is aimed finding out which cyanobacteria are affected by $_L-lysine $ and what concentration of$_L-lysine $ inhibits cyanobacteria. The 20 samples of Microcystis sp. have been tested. To prove the growth inhibition on Microcystis sp., double-layered agar method and microplate method have been used. When the concentration of $_L-lysine $ is as heavy as 100 ${\mu}g\; ml^{-1}$~300 ${\mu}g\; ml^{-1}$, some Microcystis sp. have made halo zone. Some Microcystis sp. have shown so high activity as to be inhibited in their growth by the $_{L}$-lysine of concentration 10 ${\mu}g\; ml^{-1}$ with microplate method. These activities are various in accordance with every species. In additions, the microplate method has been proven to be an easy way which examine the lytic activity on the species of algae.e.

• Korean Journal of Microbiology
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• v.46 no.3
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• pp.296-302
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• 2010

Microcystis (Cyanobacteria, Chroococcales) is one of the green tide-causing organisms in freshwaters, and some species produce microcystin that is hepatotoxin. In the aspects of freshwater quality controls and health concerns, therefore it is necessary to manage the harmful organisms. In the present study, RNA polymerase beta subunit (rpoB) gene sequences of Microcystis were determined and characterized in order to use a potential marker for the molecular detections of the species. Microcystis rpoB showed high divergences of DNA similarity and genetic distances when compared with those of 16S rRNA, and the molecular differences were statistically significant (Student t-test, p<0.05). Parsimony analyses showed the rpoB gene evolves more than 2-fold faster than 16S rRNA. In addition, phylogeny of the rpoB gene separated each M. aeruginosa strain more clearly compared with a 16S rRNA tree. This study found that the order Chroococcales, including Microcystis, has approximately two rRNA operons and single copy of the rpoB gene in their chromosomes. These results suggest that the rpoB gene is a useful marker for the molecular phylogenetics and the detection of Microcystis.

• Journal of Environmental Science International
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• v.12 no.9
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• pp.935-941
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• 2003

To investigate the interaction of bacteria and Microcystis isolated from a hypertrophic reservoir(Seo-Nakdong River), the response of five bacteria in relation to the different treatment of Microcystis and microcystin production by addition of dominant bacteria Staphylococcus sciuri were examined. Five bacteria (S. sciuri, S. capitis, S. epidermis, Pseudomonas aeruginosa and Aeromonas aimonicida) were identified from the reservoir. In the experiment of bacterial response, two types of bacterial growth pattern were observed. All bacteria showed active growth in heated Microcystis-added media. Especially, three species of bacteria (S. sciuri, S. capitis and P. aeruginosa) among them showed active growth in live Microcystis-added media. In Microcystis response, increase of microcystin production showed when dominant bacteria, S. sciuri was added.

• ALGAE
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• v.17 no.3
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• pp.153-159
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• 2002

Partial 16S rRNA gene sequences of seven cyanophycean strains from the National Instiute of Environmental Research of Korea - Microcystis aeruginosa, M. aeruginosa f. aeruginosa, M. ichthyoblade, M. viridis, Anabaena flos-aquae, and Oscillatoria sancta - were analyzed and the phylogenetic relationship of Microcystis among Cyanophyceae were evaluated. Based on sequence analysis results, Microcystis is monophyletic, the clade of which supported 100% bootstrap tress, and distinguished clearly from the other taxa. Therefore, the partial 16S rRNA gene sequences can be a useful and efficient tool for distinguishing Microcystis from other cyanophycean without axenic culture or cloning.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.10
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• pp.556-560
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• 2017

This research carried out to evaluate the disadvantage of pre-chlorination and the effect of polyamine as coagulant aids for treating the blooming water with Microcystis sp.. Pre-chlorination on blooming water makes the colony of Microcystis sp. to the smaller size. Coagulation with polyamine advanced treatment efficiency not only turbidity but also particulate matters especially less then $5{\mu}m$ size for the blooming water compared with using alum alone. Particle count was more sensitive than turbidity on water quality management of settlement and filtrate.

• Korean Journal of Ecology and Environment
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• v.37 no.1 s.106
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• pp.64-69
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• 2004

Growth inhibition of Microcystis aeruginosa was examined with single-or mixed treatment of algicidal bacterium Streptomyces neyagawensis and heterotrich ciliate Stentor roeseli, which isolated from natural freshwater. The harmful Cyanobac-terium, Microcystis aeruginosa density was effectively suppressed by the algicidal bacterium Streptomyces neyagawensis, and the bacterial biomass was few changed. The heterotrich ciliate S, roegeji isolated from the eutrophic Pal'tang riverine, Korea suppressed the algal biomass effectively. But mixed-treatment of both bio-agents was less effective, leading to an increase in algal density.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.3
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• pp.505-510
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• 2000

In this study the effects of pre-chlorination on the coagulation of water which contain Microcystis aeruginosa. were investigated on the laboratory scale. We prepared the sample of $10^5cell/mL$ Microcystis aeruginosa and then applied 0.2, 1.0, 10 mg-Cl/L chlorine on the sample After reaction period(1 minute and 1 hour), each sample was coagulated. As a result, after 0.4 mg-Al/L coagulant dose, turbidities of all samples were below 2 mg-Kaolin/L. Turbidity was not affected by chlorine dose. As the dose of chlorine was increased, the residual aluminum was decreased, but result of $UV_{254}$ was adverse.

• Journal of Environmental Science International
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• v.11 no.7
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• pp.705-711
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• 2002

In order to determine the factors causing Microcystis spp. bloom in the lower Nakdong River (Mulgum), we prepared wide ranges of pH, nutrient(N, P) concentration and the light through an enclosure experiment far 10days (pH gradient. 6.5, 7.5, 8.5, 9.5; gradient of N, P: ${\frac{1}{2}}DW+{\frac{1}{2}}River$ Water (RW), RW only; four different levels of nutrient addition/day; light: 100, 85, 60, 30, 15% of full sun light). From three days, the difference of Microcystis density in each enclosures was observed. The high density of Microcystis was maintained in the treatments over pH 9.5 and 85% of full sun light. However, in all nutrient treatments, relatively lower cell density than that of pH and light treatments was observed. These results suggested that pH and light input may play more important roles than nutrients in the early development of Microcystis bloom in the eutrophic lower Nakdong River.