• Korean Journal of Environmental Biology
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• v.30 no.1
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• pp.54-63
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• 2012

This study characterizes three $Anabaena$ strains and 5 $Trichormus$ strains isolated from Korean waters and 3 $Anabaena$ $flos-aquae$ strains procured from the UTEX based on morphological features and molecular analyses. The $Anabaena$ and $Trichormus$ isolates were morphologically assigned to $A.$ $variabilis$ K$\ddot{u}$tzing and $T.$ $variabilis$(K$\ddot{u}$tzing ex Bornet et Flahault) Kom$\acute{a}$rek et Anagnostidis, respectively. The $Anabaena$ and $Trichormus$ strains differed significantly in the mean length of their vegetative cells. The 16S rRNA genes from the $Anabaena$ strains showed a 100% identity to that from $A.$ $variabilis$ ATCC 29413, while the 16S rRNA genes from the $Trichormus$ strains showed a 99.9% identity to that from $T.$ $variabilis$ GREIFSWALD. The overall topology was in agreement for the 16S rRNA gene and $cpcBA$-IGS trees in the both tree-constructing methods. In a neighbor-joining tree based on the 16S rRNA gene, the 3 $Anabaena$ strains were asso-ciated with $A.$ $variabilis$, the 5 $Trichormus$ strains with $T.$ $variabilis$, and the 3 $Anabaena$ (UTEX) strains were with $Nostoc$. To date, this is the first report on $A.$ $variabilis$ and $T.$ $variabilis$ strains originating from Korea.

• The Korean Journal of Ecology
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• v.14 no.1
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• pp.87-99
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• 1991

Changes of phycobiliproteins(PBP) quantity and ferredoxin-NADP reductase(FNR) activity were investigated in various light illuminated cyanobacteria, Anabaena variabilis. PBP components were increased under blue light illumination, whereas decreased under red light illumination. PBP contents were twofolds in blue light than in red light. In view of the PBP composition, allophycocyanin(APC) in red light was higher 5.5% and phycoerythrocyanin(PEC) in blue light was higher 2.2% than in white light-illuminated PBP. It was suggested that PBP changes in bule light be the results of regulation of photosysthetic efficiency and protection of photosystem, whereas PBP changes in red light be effected by adaptation of adequate harvesting of light energy in photosystem. Changes of FNR activity were highest in red light, and sequenced lower to blue light and green light. It means that light-dependent production rate of NADP is the highest in red light. The difference of values was larger than that of values in comparison of red and blue light. It was suggested that increasing of FNR activity be due not to the function of isozyme, but to the synthesis of enzymes. Because of NAD/NADP regulation-effect to metabolism, it was considered that FNR activity might influence the metabolism indirectly and explain the probability of regulation in pathways of key enzyme activation. FNR activity was directly proportional to intensity of light. Optimum temperature and pH were about 25℃ and 7.5, respectively.

• Korean Journal of Microbiology
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• v.30 no.5
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• pp.391-396
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• 1992

Anabaena variabilis A TCC 29413. a photoautotrophic and nitrogen fixing cyanobacteria. was investigated on the environmental factors regulating the growth and nitrogen lixation activity. A good growth of cyanobacteria] cells was observed due to nitrogen t1xation by the heterocyst differentiation in nitrogen free Allen and Arnon (]/8) medium. The nitrogenase activity was appeared to be in proportion to the cell growth lor 6 days then drastically decreased in the later growth period when the nitraTe was accumulated to high level in the culture to cause the inhibition. The optima] conditions lilr the cell growth and nitrogenase activity of A. varillbili.l were anaerobic. IO.OO0 lux. $30^{\circ}C$ and pH 8 with the nitrogen Cree minimal medium. The activity was significantly inhihited by the low concentrations of ammonium and nitrate. but was stimulated b) the ]ow Ieve] of phosphate and carbonate sources. The treatments of several toxic heavy metals showed strong inhibition of the cell growth and nitrogenase activity by O.3~10 ppm in the order of $Hg^{2+}$ > $Cd^{2+}$ > $Co^{2+}$ > $Zn^{2+}$ > $Ph^{2+}$, and the concentrations for 50% inhibition of the maximum activity were 0.41. 0.47. 0.5 L 0.66 and 8.1 ppm. respectively. The addition of carbohydrates (0.5~ 1.0%) in the dark condition stimulated the growth and activity in the order of sucrose > fructose > glucose.

• Journal of Microbiology and Biotechnology
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• v.12 no.1
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• pp.137-141
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• 2002

Anabaena variabilis ATCC 29413 grew in chromium (Cr) containing Chu-10 (basal) and nitrate-supplemented media, and the growth of the organism in $100{\mu}M$ chromium was found to be 50% of that in control medium. The growth in nitrate $({NO_3}^-)$ supplemented cultures was better as compared to cultures grown in basal medium. Free cells from basal and nitrate-supplemented media removed 5.2 and 7.4 nmol of chromium $mg^{-1}$protein in 8 h, respectively, from the medium containing $30{\mu}M$ chromium. The efficiency of chromium removal increased 7-fold in imidazole buffer (0.2 M, pH 7.0). A cell density equivalent to $100{\mu}g$ protein $ml^{-1}$ was found to be optimum for maximum Cr removal. Entrapment of cells in calcium-alginate beads did not affect the rate of Cr uptake by the cells. The efficiency of the laboratory-scale continuous flow bioreactor $(12.5{\times}2cm)$ loaded with alginate-immobilized cells (10 mg protein) and fed with $30{\mu}M$ chromium solution was compared at different flow rates. The efficiency of the bioreactor varied with flow rates. In terms of percent removal of Cr from influent, a flow rate of 0.1 ml $min^{-1}$ was found to be optimum for 6 h (54% Cr removal efficiency). Maximum amount of Cr (883 nmol) was removed by the cells in 3 h at a flow rate of 0.5 ml $min^{-1}$. The potential use of A. variabilis in removing Cr from industrial effluents is discussed.

• Korean Journal of Environmental Biology
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• v.34 no.2
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• pp.91-96
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• 2016

This study presents the potentiality of harmful algal bloom (HAB) control through the zooplankton, Daphnia magna. In case of co-cultivated D. magna with cyanobacteriums (Microcystis aeruginosa, Anabaena variabilis, and Limnothrix planctonica), the D. magna showed the $80.2{\pm}4.2%$, $39.7{\pm}4.0%$, and $25.9{\pm}10.9%$ of control efficiency for M. aeruginosa, A. variabilis and L. planctonica, respectively. Furthermore, algal control was investigated by using supernatant including metabolite/secretion of D. magna. The algal control efficiencies of supernatant were recorded as $24.9{\pm}9.9%$ and $8.9{\pm}4.0%$ for M. aeruginosa and A. variabilis, respectively. From the results of present study, it may be possible to provide a feasible way for development of eco-friendly HAB control methods.

• International Journal of Industrial Entomology and Biomaterials
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• v.28 no.2
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• pp.32-38
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• 2014

Food consumption and conversion efficiency of eri silkworm Samia ricini Donovan were studied during $4^{th}$ and $5^{th}$ larval instars by feeding castor leaves fortified with 100, 200, 300, 400 and 500 ppm concentrations of aqueous extracts of cyanobacteria Anabaena variabilis. The nutritional indices viz., ingesta, digesta, approximate digestibility (%), reference ratio and efficiency parameters like ECI and ECD were recorded which were significantly high at 400 ppm concentration treated batches of $4^{th}$ instar larvae over control batches. The decline in nutritional efficiency parameters of $5^{th}$ instar treated larvae might be due to higher utilization of the digested food for metabolic activities. Significant difference of ECI to cocoon % and non-significant difference of ECD to cocoon% and shell were observed between the treatments and control. Cyanabacteria feed supplement contains antibiotic and nutritions factors which has reflective effect on the biological parameters in eri silkworm and therefore has greater application in commercial eri silkworm rearing.

• Journal of Microbiology and Biotechnology
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• v.18 no.5
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• pp.918-925
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• 2008

Controlling the light energy and major nutrients is important for high cell density culture of cyanobacterial cells. The growth phase of Anabaena variabilis can be divided into an exponential growth phase and a deceleration phase. In this study, the cell growth in the deceleration phase showed a linear growth pattern. Both the period of the exponential growth phase and the average cell growth rate in the deceleration phase increased by controlling the light intensity. To control the light intensity, the specific irradiation rate was maintained above $10\;{\mu}mol/s/g$ dry cell by increasing the incident light intensity stepwise. The final cell density increased by controlling the nutrient supply. For the control of the nutrient supply, nitrate, phosphate, and sulfate were intermittently added based on the growth yield, along with the combined control of light intensity and nutrient concentration. Under these control conditions, both final cell concentration and cell productivity increased, to 8.2 g/l and 1.9 g/l/day, respectively.

• Microbiology and Biotechnology Letters
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• v.48 no.2
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• pp.205-214
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• 2020

Cyanobacteria are microorganisms which have important roles in the nitrogen cycle due to their ability to fix nitrogen in water and soil ecosystems. They also produce valuable materials that may be used in various industries. However, some species of cyanobacteria may limit the use of water resources by causing harmful algal blooms in water ecosystems. Many culture collection depositories provide cyanobacterial strains for research, but their systematic preservation is not well-developed in Korea. In this study, we developed a method for the cryopreservation of the cyanobacteria Trichormus variabilis (syn. Anabaena variabilis), using alginate microcapsules. Two approaches were used for the experiments and their outputs were compared. One of the methods involved the cryopreservation of cells using only a cryoprotectant and the other used the cryoprotectant within microcapsules. After cryopreservation for 35 days, cells preserved with both methods were successfully regenerated from the initial 1.0 × 10⁵ cells/ml to a final concentration of 6.7 × 10⁶ cells/ml and 1.1 × 10⁷ cells/ml. Irregular T. variabilis shapes were found after 14 days of regeneration. T. variabilis internal structures were observed by transmission electron microscopy (TEM), revealing that lipid droplets were reduced after cryopreservation. The expression of the mreB gene, known to be related to cell morphology, was downregulated (54.7%) after cryopreservation. Cryopreservation using cryoprotectant alone or with microcapsules is expected to be applicable to other filamentous cyanobacteria in the future.

• Bulletin of the Korean Chemical Society
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• v.34 no.2
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• pp.379-383
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• 2013

For the production of ethanol from freshwater cyanobacteria, a new pretreatment method using supercritical fluid was introduced. In this study, it was found that the supercritical fluid could penetrate inside the cell wall and help to liberate starch from cyanobacterial cells which resulted in the increase of the efficiency of ethanol production. For Microcystis aeruginosa, supercritical fluid pretreatment increased the amount of ethanol produced from cyanobacteria from 1.53 g/L to 2.66 g/L. For Anabaena variabilis, the amount of ethanol was increased from 1.25 g/L to 2.28 g/L. With use of supercritical fluid pretreatment, the efficiency of the process to obtain higher ethanol yields from freshwater cyanobacteria was improved upto 80%. The optimum temperature and pressure conditions for supercritical fluid pretreatment were determined as the temperature of $40^{\circ}C$ and the pressure of 120 atm. This study demonstrates the feasibility of using supercritical fluid pretreatment for ethanol production using freshwater cyanobacteria.

• Journal of Microbiology and Biotechnology
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• v.29 no.1
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• pp.59-65
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• 2019

Fusaricidin analogs, produced by Paenibacillus polymyxa, were tested for selective control of a major bloom-forming cyanobacterium, Microcystis sp. Fusaricidin (A and B mixtures) and four analogs were isolated from P. polymyxa E681 and investigated for their inhibition of cyanobacterial cell growth. Among the four fusaricidin analogs, fraction 915 Da (designated as Fus901) showed growth inhibition activity for Microcystis aeruginosa but not for Anabaena variabilis and Scenedesmus acutus. Microcystin concentration decreased up to 70% and its content per cell also decreased over 50% after 3 days. Fusaricidin exhibited growth inhibition against Gram-positive bacteria but Fus901 did not. Molecular weights of fusaricidin A and B were 883 Da and 897 Da, whereas that of Fus901 was 915 Da. Structure analysis by a ring-opening method revealed a linear form for Fus901. Expression of the pod gene related to oxidative stress was increased 2.1-fold by Fus901 and that of mcyD decreased up to 40%. These results indicate that Fus901 exerts oxidative stress against M. aeruginosa. Thus, Fus901 can be used as a selective cyanobactericide without disturbing the ecological system and could help in decreasing the microcystin concentration.