• Biotechnology and Bioprocess Engineering:BBE
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• v.5 no.6
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• pp.418-421
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• 2000

A new direct colorimetric assay of microcystin in water and algal samples is proposed consisting of two procedures as follows: 1) the elimination of phosphorus in the sample and concentration of microcystin using a C(sub)18 cartridge, 2) the detection of the released phosphorus by the ascorbic acid method and determination of protein phosphatase (PP) inhibition by microcystin. The optimum amounts of phosphorylase ${\alpha}$ and PP-1 in 50 ${\mu}$L concentrated sample were 50$\mu\textrm{g}$/50${\mu}$L buffer and 1.0unit/50${\mu}$L buffer, respectively, for the best assay. The pH for the maximum activity of PP-1 was 8. The minimum detectable concentration for this method was about 0.02$\mu\textrm{g}$/L, which is sufficient to meet the proposed guideline level of 1$\mu\textrm{g}$ microcystin/L in drinking water. Consequently, it would seem that the proposed direct colorimetric assay using PP is a rapid, easy, and convenient method for the detection of microcystin in water and algal samples.

• Korean Journal of Ecology and Environment
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• v.34 no.3 s.95
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• pp.175-184
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• 2001

The temporal and diel changes of cyanobacterial cell density, species composition, and cyanobacterial toxins (microcystin-RR, -YR, -LR) were examined for the outflow water of Lake Suwa in Japan from May to October, 1998. The highest total cell densities of Microcystis were observed in July and September, when the dominant phytoplankton was Microcystis ichthyoblabe and M. viridis, respectively. Both the species composition and total cell density of Microcystis affected the variation of the concentration of three microcystin variants. Only microcystin-RR(MC-RR) and -LR (MC-LR) were detected in July when Microcystis ichthyoblabe dominated, while microcystin-RR, -YR (MC-YR) and -LR were detected in August and October when Microcystis viridis dominated. The microcystin concentration and the cell density of Microcystis in the outflow water showed diel variations; the ratio of maximum to minimum value was $3{\sim}20$ fold far microcystin concentration, and $5{\sim}31$ fold for cell density. The diel variations of toxin concentration as well as Microcystis cell density was closely related to the diel variation of wind. During the windy period, when higher speeds occurred in the afternoon hours than morning hours, both the cell density of Microcystis and microcystin concentration tended to increase in the morning and decrease in the afternoon. The results of this study suggest that controlling the timing of lake discharge at the floodgate or intake tower can be useful for water resource management with respect to decreasing cyanobacteria biomass within intake water.

• Journal of environmental and Sanitary engineering
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• v.20 no.2 s.56
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• pp.1-11
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• 2005

Cyanotoxin, microcystins commonly produced by cyanobacterial affect various aquatic organisms and even human health. Kinds, structures, measurement analysis, toxicity and removal of Microcystin-LR were explained and discussed.

• Journal of Environmental Science International
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• v.26 no.3
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• pp.345-362
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• 2017

The primary purpose of this study was to determine the risk of various disease outcomes due to exposure to cyanobacteria toxin (microcystin-LR) through drinking water in a Korean watershed. In order to determine the risk in a more quantitative way, the risk assessment framework developed by the National Research Council (NRC) of the United States (US) - hazard identification, dose-response relationship, exposure assessment, and risk characterization - was used in this study. For dose-response relationships, a computer software (BenchMark Dose Software (BMDS)) developed by the US Environmental Protection Agency (EPA) was used to fit the data from previous studies showing the relationship between the concentration of microcystin-LR and various disease outcomes into various dose-response models. For exposure assessment, the concentrations of microcystin-LR in the source water and finished water in a Korean watershed obtained from a recent study conducted by the Ministry of Environment of Korea were used. Finally, the risk of various disease outcomes due to exposure to cyanobacteria toxin (microcystin-LR) through drinking water was characterized by Monte-Carlo simulation using Crystall Ball program (Oracle Inc.) for adults and children. The results of this study suggest that the risk of disease due to microcystin-LR toxin through drinking water is very low and it appears that current water treatment practice should be able to protect the public from the harmful effects of cyanobacteria toxin (microcystin-LR) through drinking water.

• Korean Journal of Ecology and Environment
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• v.33 no.1 s.89
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• pp.9-22
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• 2000

The decomposition processes of Microcystis aeruginosa under the light and dark conditions were investigated in relation to the change of microcystins, physicochemical and biological factors. Cyanobacterial cells from upper stream of Lake Dae-chong were collected and incubated in the matrix of raw water under the light and dark conditions without additional nutrients. The decomposition of Microcystis cells started from beginning of the experiment and most of the cells were decomposed on 12th day. Under the light condition the concentration of toxins in filtrate fractionwas increased with the increase of viscosity as the decomposition of algal cells proceed whereas no significant change was observed under the dark condition. Microcystin- RR was most labile toxin than the other two microcystins because it was identified mainly in lyophilized cells but detected at trace level in the filtratefraction.

• Korean Journal of Ecology and Environment
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• v.49 no.4
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• pp.393-399
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• 2016

This study was conducted to investigate whether the presence of mcy gene and microcystin production are related to morphological characteristics of Korean Microcystis species. We isolated 6 different species of Microcystis (M. aeruginosa, M. ichthyoblabe, M. flos-aquae, M. novacekii, M. viridis and M. wesenbergii) from drinking water supply dams (Yeongchun, Ankei, Gachang), and used microscopic method for morphological identification, molecular method for amplifying a partial region of mcyB gene and ELISA method for microcystin analysis. In the present study, 80% of M. aeruginosa strains contained mcy gene, followed by 45% (10 strains) of M. icthyoblabe, 33% (1 strain) of M. wesenbergii, and 11% (4 strains) of M. flos-aquae. Each percentage of mcy gene in Microcystis morphospecies was similar to that of microcystin production in Microcystis morophospecies. In conclusion, the present study shows that molecular method using mcy gene primers can be used as an indirect indicator for the monitoring of toxic cyanobacteria (Microcystis).

• Journal of Korean Society on Water Environment
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• v.18 no.3
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• pp.321-326
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• 2002

On this study, removal method for microcystin, toxic substance released from the blue-green algae, using chloride was investigated. 82 ~ 98% of Microsystin were removed within 1 hr when sample had microsystin only. However, if the sample had algae cell removal efficiency was decreased to 50%, except the concentration of chloride $10Cl-mg/{\ell}$. As a result, intermediate-chlorination which dose chloride after coagulation process is considered the optimum method for the removal of microcystin because most of algae cell could remove during the coagulation process.

• Journal of the Korean Chemical Society
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• v.45 no.6
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• pp.524-531
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• 2001

Micro-HPLC/IS/MS after solid phase extraction has been employed to enhance the accu-racy in the determination of toxic microcystins, such as microcystin-LR, -YR and -RR. The absorbance at 238 nm in HPLC/UV and characteristic spectra of 135 m/z and $[M+H]^+$ m/z in MS have been widely monitored to identify those microcystin-LR, -YR and -RR. In this study, new lines at 507 m/z for LR, 520 m/z for RR and 532 m/z for YR have been additionally detected in the micro-HPLC/IS/MS spectrum, corresponding to double charge. The micro-HPLC/IS/MS methodology has been applied to investigate the presence of the toxic microcystins in Taecheong lake.

• Korean Journal of Microbiology
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• v.44 no.3
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• pp.251-257
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• 2008

Four potential microcystin-producing cyanobacteria were isolated from large reservoirs which act as sources of drinking water supply in Korea. Strain DC-2, YD-l, and YD-6 were closely related to Microcystis aeruginosa based on the analysis of l6S rRNA gene and mcyA gene sequences. mcyA gene sequence of YDS2-3, isolated from Yongdam Reservoir, was closed to that of M. aeruginosa, whereas l6S rRNA gene sequence was not related to the known sequences of microcystin-producing cyanobacteria indicating this strain can be a novel cyanobacterium belonging to the genus Microcystis. When mcyA gene sequences of isolated cyanobacteria were compared with the mcyA gene sequence library of two reservoirs, the sequence of DC-2 matched with the dominant ones.

• Korean Journal of Ecology and Environment
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• v.47 no.spc
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• pp.19-30
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• 2014

Microcystins (MCs) produced by cyanobacteria are severe hepatotoxins for mammalian and protein phosphatase inhibitors. Irrigation water for grain and vegetables is often contaminated with cyanobacteria and microcystin during warm seasons. We assessed the effects of various concentrations (0, 0.01 to $10{\mu}gmL^{-1}$) of microcystin-LR (MC-LR) and microcystin-RR (MC-RR) exposure on Oryza sativa (rice) and Brassica oleraces var. italica (broccoli). The $EC_{50}$ of leaves and roots of rice was 0.9 and $1.1{\mu}gMC-LRmL^{-1}$, respectively. The no observed effect level (NOEL) of rice was less than $0.1{\mu}gmL^{-1}$ ($100{\mu}gL^{-1}$). The $EC_{50}$ of the stems and roots of broccoli was 8.7 and $7.2{\mu}gMC-RRmL^{-1}$, respectively. There was no difference in the germination rate of broccoli among microcystin-RR concentrations. After exposure to 0, 0.01 to $10{\mu}gmL^{-1}$ MC-RR for seven days, 14, 89 and 154 ng mg-1 (dry weight) MC-RR accumulated in B. oleracea. These $EC_{50}$ values showed that microcystin-LR and -RR affected the growth of rice and broccoli. These findings suggest that MC is carried into terrestrial ecosystems via irrigation, and that the biota of higher ecological niches can be influenced by MC through bioaccumulation. Therefore, a guideline for MC concentrations in irrigation water should be set using the NOEL.