• ALGAE
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• v.34 no.4
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• pp.267-275
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• 2019

Three new species of the genus Micractinium were collected from five localities on the South Shetland Islands in maritime Antarctica, and their morphological and molecular characteristics were investigated. The vegetative cells are spherical to ellipsoidal and a single chloroplast is parietal with a pyrenoid. Because of their simple morphology, no conspicuous morphological characters of new species were recognized under light microscopy. However, molecular phylogenetic relationships were inferred from the concatenated small subunit rDNA, and internal transcribed spacer (ITS) sequence data indicated that the Antarctic microalgal strains are strongly allied to the well-supported genus Micractinium, including M. pusillum, the type species of the genus, and three other species in the genus. The secondary structure of ITS2 and compensatory base changes were used to identify and describe six Antarctic Micractinium strains. Based on their morphological and molecular characteristics, we characterized three new species of Micractinium: M. simplicissimum sp. nov., M. singularis sp. nov., and M. variabile sp. nov.

• Korean Journal of Ecology and Environment
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• v.34 no.2 s.94
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• pp.90-97
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• 2001

The seasonal changes in phytoplankton standing crops, species composition, dominant species, species diversity and physico-chemical characteristics in Woopo and Mokpo swamps were studied from January to December, 1998. Phytoplankton of a total 353 taxa were identified, the composition of phytoplankton community was characetrized by green algae and diatoms and quantity composition of standing crops was dominated by green alga Oscillatoria sp. was especially prominent. The standing crops varied from 108 cells/ml and 118 cells/ml to 19,178 cells and 38,393 cells/ml in Woopo and Mokpo swamps, respectively. The maximum algal density was observed in November, Micractinium pusillum and Oscillatoria sp. usually contributed 83.2% to total cell numbers in Woopo swamp. However, the maximum density occurred in May when Oscillatoria sp. formed bloom in Mokpo swamp. The low species diversity of the phytoplankton coincided with maximum standing crops of the filamentous blue-green alga Oscillatoria sp. and green alga Micractinium pusillum in May and November.

• Korean Journal of Environmental Biology
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• v.38 no.1
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• pp.61-70
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• 2020

A eukaryotic microalga was isolated from seawater in Janghang Harbor, Korea and its morphological, molecular, and physiological characteristics were investigated. Due to its simple morphology, no distinctive characters were found by morphological observation, such as light microscope or scanning/transmission electron microscopy (S/TEM). However, molecular phylogenetic evidence inferred from the concatenated small subunit (SSU) 18S rRNA and internal transcribed spacer (ITS) sequence data indicated that the isolate belonged to the newly described Micractinium singularis. Furthermore, it was clustered with Antarctic Micractinium strains and it also showed a psychrotolerant property, surviving at temperatures as low as 5℃. However, its optimal growth temperatures range from 15℃ to 25℃, indicating that this microalga is a mesophile. Additionally, gas chromatography-mass spectrometry (GC/MS) analysis showed that the isolate was rich in nutritionally important omega-3 polyunsaturated fatty acid, and high-performance liquid chromatography analysis (HPLC) revealed that the high-value antioxidant lutein was biosynthesized as an accessory pigment by this microalga, with glucose as the major monosaccharide. Therefore, in this study, a Korean marine M. singularis species was discovered, characterized, and described. It was subsequently added to the national culture collections.

• ALGAE
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• v.37 no.2
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• pp.175-183
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• 2022

Polar microorganisms produce physiologically active substances to adapt to harsh environments, and these substances can be used as biomedical compounds. The green microalga Micractinium variabile KSF0031, which was isolated from Antarctica, produced phytol, a natural antimicrobial agent. Furthermore, several polyunsaturated fatty acids (PUFAs), including omega-3, exhibit antioxidant properties. Here statistical methods (Plackett-Burman design and Box-Behnken design) were used to optimize the culture medium of KSF0031 to improve biomass production, and K₂HPO₄, MgSO₄·7H ₂O, and ammonium ferric citrate green (AFCg) were selected as significant components of the culture medium. Changes in the concentration of K₂HPO₄ and MgSO₄·7H ₂O as positive factors and AFCg as a negative factor affected cell growth to a remarkable degree. The biomass production in a 100 L culture using the optimized medium for 24 d at 18℃ was improved by 37.5% compared to that obtained using the original BG-11 medium. The quantities of PUFAs and phytol obtained were 13 mg g^-1 dry cell weight (DCW) and 10.98 mg g^-1 DCW, which represent improved yields of 11.70% and 48.78%, respectively. The results of this study could contribute to an improved production of phytol and fatty acids from Antarctic microalgae in the biomedical industry.

• Journal of Environmental Science International
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• v.4 no.3
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• pp.167-176
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• 1995

A study on phytoplankton community was carried out from June, 1992 to May, 1993 at selected stations in Hoedong Reservoir. The phytoplankton are identified as 176 taxa including 5 phylum, 67 genera. The important species in this reservoir were Asterionella formosa, C meneghiniana, Dictyosphaerium plilchellum, Fragilaria crotonensis, Melosira distans, M grantulata, M. granulata var. angustissima, M. granulate var. angntissima f. spirdis, Micractinium pussillum, Microcystis aeruginosa, Pundorina morn, Pediastrum boryanum, P. duplex, Peridinium sp., Scenedesmus quadriauda, Synedra acus, S. rumpens and S. ulna. The causative species of water bloom were identified as Microcystis aeruginsa, Trahellomonas hispida, Ceratium hirwdinella, Peridinium sp., Melosira italica, Staurastrum dorsidentiferum var. onatum in the area. During the study periods standing crcps of phytoplankton were maximum in August, 1992 and minimum in December 1992. The species dominance index and diversity index were ranged 24.7-99.9, 0.001-3.06, respectively. Key Words : phytoplankton community, causative species of water bloom, standing crops. dominance index, species diversity index.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.2
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• pp.247-253
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• 2004

Major species of Lake Deganuma has varied depending on the season. Namely, there are Micractinium pusillum, chlorella., Scenedesmus sp. shown up in spring season, Microcystis aeruginosa, Microcystis wesenbergii, Anabena spiroides in summer and autumn season and Cyclostephanos invisitatus, Diatoma in winter season in the Lake. As the number of plankton increased, the zeta potential on their surface of them decreased. For this reason, they were dispersed in the lake though the population increased. Zeta potential of M. aeruginosa showed -20mV when their outer size got smaller. As for coagulant dosing in DAF, large amount of coagulant was effective to get lots of sludge during water treatment.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.4
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• pp.289-293
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• 2013

The changes of phytoplankton community in downstream of the Nakdong River from 2002 to 2012 was investigated. Phytoplankton biomass (chlorophyll-a concentration) was gradually increased, but dominant species cell number was gradually decreased. In changes of percentage of dominant species cell number from 2002 to 2012, Diatoms was gradually decreased, but blue-green algae was gradually increased. In changes of annual percentage of dominant period, Diatoms showed high percentage from November to May, and dominant period (%) of diatoms was 56%~74% from June to September, also dominant period of diatoms was about 300 days every year. Percentage of dominant species cell number and dominant period of blue-green algae was 68%~94% and 26%~ 36% from June to September, respectively. And green-algae showed low percentage from April to September. In the transition patterns of diatoms and blue-green algae, Stephanodiscus spp. was the highest dominant species, from December to May, and Aulacoseira spp. and Fragilaria spp. were showed high dominant percentage from May to October. In the case of blue-green algae, Microcystis spp. was the highest dominant species, from May to November, also in the case of green algae, Actinastrum spp., Pediastrum spp., Micractinium spp. and Pandorina spp. were dominant species from April to September.

• ALGAE
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• v.18 no.3
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• pp.207-215
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• 2003

Dynamics of phytoplankton communities were investigated at five stations in Youngsan River from December 1995 to November 1996. Phytoplankton were identified to the total of 466 taxa, which were composed of 136 genera, 438 species, 27 varieties and 1 forma. The standing crops ranged 1,163-50,765 cells ${\cdot}ml^{-1}$ during the investigation periods. The variation of classes was in order to Chrysophyceae - Bascillariophyceae - Chlorophyceae at St. 1 and was only Bacillariophyceae at the other stations. The dominant species were 12 taxa including Aulacoseira ambigua, A. garnulata, Cyclotella meneghiniana, C. pseudostelligera, Chlorella vulgaris, Dinobryon sertularia, Flagilaria elliptica, Monoraphidium contortum, Micractinium pusillum, Nitzschia palea, Scenedesmus grahneisii and Stephanodiscus hantzschii f. tenuis. The standing crops of dominant species ranged from 10.6% to 94.7%. The genus Dinobryon in Chrysophyceae was dominant species at St. 1 in December 1995, but not recorded in the other months. The dominant species were composed with the planktonic diatoms from winter to spring and were the tychoplanktonic and the benthic species at St. 2-5 from summer to fall. The relationships between total standing crops and water temperature, pH, $NH_4$, $NO_2$, $NO_3$ and $PO_4$ showed low positive or negative coefficients. Stephanodiscus hantzschii f. tenuis had low positive or negative coefficients with water temperature, $NH_4$, $NO_2$, $NO_3$ and $PO_4$. The fluctuations of standing crops in the Youngsan river phytoplankton community were not caused by a single factor but controlled by the complex factors with interaction between phytoplankton community and envirowmental factors.

• Journal of Korean Society of Water and Wastewater
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• v.36 no.5
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• pp.249-260
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• 2022

The effect of permanganate oxidation was investigated as water treatment strategy with a focus on comparing the reaction characteristics of NaOCl and sodium permanganate (NaMnO₄) in algae (Monoraphidium sp., Micractinium inermum, Microcystis aeruginosa)-contained water. Flow cytometry explained that chlorine exposure easily damaged algae cells. Damaged algae cells release intracellular organic matter, which increases the concentration of organic matter in the water, which is higher than by NaMnO₄. The oxidation reaction resulted in the release of toxin (microcystin-LR, MC-LR) in water, and the reaction of algal organic matter with NaOCl resulted in trihalomethanes (THMs) concentration increase. The oxidation results by NaMnO₄ significantly improved the concentration reduction of THMs and MC-LR. Therefore, this study suggests that NaMnO₄ is effective as a pre-oxidant for reducing algae damage and byproducts in water treatment process.

• 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.