• ALGAE
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• v.18 no.3
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• pp.233-238
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• 2003

Cyanobacteria were dominant from June to September in the Nakdong River and the Hoedong Reservoir. Microcystis aeruginosa was dominant from June to September; Anabaena flos-aquae from June to August and Aphanizomenon flos-aquae from July to August. Cyanobacterial neurotoxins, Anatoxin-a and saxitoxin were analyzed by electrospray ionization-mass spectrometry with strains of Aphanizomenon flos-aquae NIES-81 and Anabaena flosaquae NIER-10002. Anatoxin-a was not detected from the cultured Anabaena flos-aquae nor from the wild samples. Low levels of saxitoxin were detected in the cultured Aphanizomenon flos-aquae however, those of field samples were below the detection limit.

• Journal of Korean Society on Water Environment
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• v.33 no.5
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• pp.538-545
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• 2017

The purpose of this study is to investigate growth response and toxigenicity under various temperature and nutritional conditions, in order to understand the physioecological characteristics of Aphanizomenon flos-aquae, which is a bloom-forming cyanobacterium in the Nakdong River. The strain was inoculated into media under combinations of four temperatures (4, 12, 21, $30^{\circ}C$) and three nutrients (modified CB medium, P-depleted CB medium, N-depleted CB medium) for 28 days. The algae-inhibition tests were performed to assess the potential allelopathic effects of the strains' filtrates on the growth of four algae strains (Microcystis aeruginosa, Aulacoseria ambigua f. spiralis, Aphanizomenon flos-aquae, Scenedesmus obliquus). Toxin production of a strain was measured by Enzyme-Linked ImmunoSolbent Assay (ELISA). The optimal growth temperature (Topt) of strains was $19.9^{\circ}C$ ($18.3-21.2^{\circ}C$), and the temperature range for growth was from $-0.3^{\circ}C$ to $34.3^{\circ}C$. Specific growth rate (${\mu}$) in modified CB medium varied from 0.10 to $0.16day^{-1}$, and the maximum growth rate (${\mu}_{max}$) was $0.17day^{-1}$. Although growth curves under N-existed and N-depleted conditions were almost the same, growth under N-depleted condition was relatively slowed (${\mu}=0.09$ to $0.14day^{-1}$), with a decreased maximum cell density. However, growth under the P-depleted condition was restricted for all temperatures, Two stains of Aphanizomenon flos-aquae were confirmed as not producing toxins, because saxitoxin and cylindrospermopsin were not detected by ELISA. The exudates or filtrates from the Aphanizomenon flos-aquae (DGUC003) resulted in significant inhibition of algal growth on the Aulacoseira ambigua f. spiralis (DGUD001) and Aphanizomenon flos-aquae (DGUC001) (p < 0.01).

• Journal of Food Hygiene and Safety
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• v.28 no.2
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• pp.188-193
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• 2013

Anatoxin-a, saxitoxin and neosaxitoxin are produced by Aphanizomenon flos-aquae that is a sort of the cyanobacteria phylum. Therefore, it is not permitted for food materials in Korea. Traditionally, the classification of cyanobacteria has been based on morphological characters such as trichome width, cell size, division planes, shape, and the presence of character such as gas vacuole. But, some diagnostic features, such as gas vacuole or akinetes, can show variation with different environmental or growth conditions and even be lost during cultivation. Therefore, we developed detection method for functional foods containing Aph. flos-aquae by PCR. To design the primer, 16S rRNA region of Aph. flos-aquae, Spirulina laxissima, and Spirulina spp. registered in the GeneBank (www.ncbi.nlm.nih.gov) have been used and for comparative analysis, BioEdit ver. 7.0.9.0. was used. As a result, we was design AFA-F1/AFA-R1 (363 bp) primer for the differentiation Aph. flos-aquae from chlorella, spirulina, green tea, and spinach. Also, it could be distinguished chlorella and spirulina products those are made to contain 1% Aph. flos-aquae.

• Journal of Ecology and Environment
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• v.40 no.3
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• pp.144-152
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• 2016

Background: The purpose of this study is to describe the morphological characteristics of the Aphanizomenon spp. and related species from the natural samples collected in the Nakdong River of South Korea. Results: Morphological characteristics in the four species classified into the genera Aphanizomenon Morren ex Bornet et Flahault 1888 and Cuspidothrix Rajaniemi et al. 2005 were observed by light microscopy. The following four taxa were identified: Aphanizomenon flos-aquae Ralfs ex Bornet et Flahault, Aphanizomenon klebahnii Elenkin ex Pechar, Aphanizomenon skujae $Kom{\acute{a}}rkov{\acute{a}}-Legnerov{\acute{a}}$ et Cronberg, and Cuspidothrix issatschenkoi ($Usa{\check{c}}ev$) Rajaniemi et al. Aph. flos-aquae and Aph. klebahnii always formed in fascicles; the others only occurred in solitary. Aph. flos-aquae was similar to Aph. klebahnii, whereas these species differed from each other by the size and shape of fascicles, which was macroscopic in Aph. flos-aquae and microscopic in the Aph. klebahnii. One of their characteristics was that trichomes are easily disintegrating during microscopic examination. C. issatschenkoi could be clearly distinguished from other species by hair-shaped terminal cell. Its terminal cell was almost hyaline and markedly pointed. Young populations of the species without heterocytes run a risk of a misidentification. Aph. skujae was characterized by akinete. Morphological variability of akinetes from natural samples collected in the Nakdong River was rather smaller than those reported by previous study. Conclusions: C. issatschenkoi are described for the first time in the Nakdong River. In addition, Aph. klebahnii and Aph. skujae are new to South Korea.

• Korean Journal of Ecology and Environment
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• v.50 no.1
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• pp.137-147
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• 2017

The identity of toxin producers remains only hypothesis unless there were identified by strain isolation and analytical confirmation of both the cyanotoxin production and the genetic identity of the monoculture. The purposes of this study were to identify a morphologic and phylogenetic classification in Aphanizomenon flos-aquae strains isolated from the Nakdong River and to investigate the potential ability of the strains to produce toxins such as saxitoxin and cylindrospermopsin using target genes. The 16S rRNA and sxtA, sxtI, cyrA, cyrJ genes were analyzed on two strains (DGUC001, DGUC003) isolated from the Nakdong River. Morphological features of the strains were observed a shape of aggregated trichomes in parallel fascicles which can reach up to macroscopic size and a hyaline terminal cell without aerotope. In addition, the 16S rRNA phylogenetic analyses showed that the strains were identified as the same species with high genetic similarity of 98.4% and grouped within a monospecific andsupported cluster I of Aphanizomenon flos-aquae selected from GenBank of the NCBI. The cyrA and cyrJ genes encoding for the cylindrospermopsin-biosynthesis were not detected in the present study. The sxtA gene was in detected both the two strains, whereas the sxtI gene which had been suggested as a suitable molecular marker to detect saxitoxin-producing cyanobacteria was not found both the strains. Thus, the two strains isolated from Nakdong River were identified as the same species of Aphanizomenon flos-aquae Ralfs ex Bornet et Flahault 1888, the two strains were confirmed as potential non-producing strains of the saxitoxin and cylindrospermopsin.

• Korean Journal of Microbiology
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• v.40 no.3
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• pp.205-210
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• 2004

The change of bacterial communities during cyanobacterial bloom was analyzed by DGGE in Daechung Reservoir from July to October in 2003. The traditional morphological analysis showed that the genera of Microcystis, Chroococcus, Oscillatoria, and Phormidium were dominated. The most frequent band in the DGGE profile by 16S rDNA sequence analysis was identified as Microcystis flos-aquae and the cyanobacterial bloom was peaked on September 2. Oscillatoria spp. were also identified and Aphanizomenon flos-aquae dominated in the middle of August. Judging from the analysis of the digitalized DGGE profiles using the cluster analysis technique, the microbial community on September 2 was considerably different from others. Consequently, it seems that the gene fingerprinting method can give not only the similar results to the traditional morphological method but also additional information on the bacterial species and similarity among the examined microbial communities.

• ALGAE
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• v.20 no.2
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• pp.133-140
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• 2005

Daily variation of phytoplankton community and environmental parameters were investigated at the lower Nakdong River (Mulgum) from January 2002 to December 2003 to investigate the dynamics of a phytoplankton community in detail. The daily results of water quality in this investigation showed pH (8.1 $\pm$ 0.7), DO (10.3 $\pm$ 2.7 $mg{\cdot}l^{-1}$), water temp. (18.8 $\pm$ 7.4°C), BOD (2.4 $\pm$ 1.0 $mg{\cdot}l^{-1}$), COD (5.3 $\pm$ 1.2 $mg{\cdot}l^{-1}$) and chl. a (43.5 $\pm$ 35.1 mg ${\cdot}m^{-3}$). The results of nutrient factors were the following: TN (3.1 $\pm$ 0.8 $mg{\cdot}l^{-1}$), NO3-N (2.5 $\pm$ 0.5 $mg{\cdot}l^{-1}$), TP (90 $\pm$ 48 ${\mu}g\;{\cdot}\;l^{-1}$), PO4-P (43 $\pm$ 30 ${\mu}g\;{\cdot}\;l^{-1}$). Dominant phytoplankton species during the study period were diatom (Stephanodiscus hantzschii, Aulacoseira granulata var. angustissima and A. italica) and cyanobacteria (Microcystis aeruginosa, Aphanizomenon flos-aquae). The small centric diatom, Stephanodiscus hantzschii, was repeatedly dominant from late fall to the following spring (mean and maximum cell density, 2.3 × 103 $\pm$ 3.8 × 103, 4.5 × 105 cells $ml^{-1}$, respectively). Pinnate diatom, Aulacoseira granulata var. angustissima and A. italica, were frequently observed all season except January to March. Cyanobacteria, Microcystis aeruginosa and Aphanizomenon flos-aquae, proliferated in summer of 2002 except in 2003 due to heavy precipitation. The dominant zooplankton species (March-early May) was rotifer (Brachionus, Keratella, Polyarthra) and cladocerans (Diaphanosoma). The daily observed dynamics of the phytoplankton community in the lower Nakdong River in this study may play an important role in increasing the detailed resolution of limnological information and serving as ecological data for future studies.

• ALGAE
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• v.21 no.1
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• pp.125-131
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• 2006

Long-term preservation of bloom-forming cyanobacteria was evaluated using cryopreservation and freeze-drying of nine strains belonging to four genera and seven species. All test strains, except Aphanizomenon flos-aquae NIER- 10028, showed partial or complete survival following cryopreservation and freeze-drying. Frozen and freeze-dried strains were preserved for more than two years and were revived monthly. Most strains showed higher post-thaw viability after cryopreservation, especially without cryoprotectant compared to freeze-drying. Microcystis aeruginosa NIER-10010, M. viridis NIER-10020, M. ichthyoblabe NIER-10023, M. novacekii NIER-10029 and Oscillatoria sancta NIER-10027 were revived after 2.5 years of cryopreservation. These results suggest that cryopreservation may be an easy and timesaving long-term preservation method for bloom-forming cyanobacteria.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2005.05a
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• pp.257-259
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• 2005

서낙동강에서 조사된 식물플랑크톤은 6강 31과 128종류로 녹조류(Chlorophyceae)가 49종류(38.3%), 규조류(Bacillariophyceae)가 44종류(34.4%)였다. 계절별로는 여름에 최고 80종, 겨울에 최소 47종으로 출현하였으나 일반적인 경우와는 상이한 결과였다. 정점별로는 여름에 정점 1에서 63종류로 가장 많은 종수를, 가을과 겨울의 정점 4에서 18종류로 가장 적은 종수로 조사되어 계절별, 정점별 출현종수의 차이는 크게 나타났다. 생태적 주요종은 모두 63종류였고 Actinastrum hantzschii var. fluviatile을 비롯한 33종류가 광분포종, 오수지표종은 Ankistrodesmus falcatus를 비롯하여 28종류, 적조원인종은 Aulacoseira garanulata var. angustissima for. spiralis를 비롯하여 23종류, 우점종으로는 Aphanizomenon flos-aquae를 비롯하여 8종류, 출현빈번종은 Asterionella formosa를 비롯하여 7종이었다. Jaccard's coefficient에 의한 집괴분석을 실시한 결과, 거의 모든 계절에서 서낙동교를 중심으로 서낙동교 상부지역(st. 1 ${\sim}$ st. 3)과 하부지역(st. 4 ${\sim}$ st. 6)으로 구분되거나 또는 담수지역(st. 1 ${\sim}$ st. 4)과 해수의 영향이 미칠 것으로 예상되는 지역(st. 5 ${\sim}$ st. 6)의 두그룹으로 그룹지어졌다.

• Korean Journal of Environmental Biology
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• v.24 no.3
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• pp.221-229
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• 2006

The effects of ultrasonication on phytoplankton were investigated in two ponds in which physicochemical and biological water quality was similar, one as a treatment and the other as a control. The samples were collected from August 18 to September 30 in 2003. Traditional morphological analysis showed that Bacillariophyceae dominated phytoplankton community in both ponds. The abundance of Cyanophyceae was lower in the phytoplankton community of the sonicated pond than that of control pond. We used DGGE (denaturing gradient gel electrophoresis) to analyze the diversity and change of phytoplankton community in two ponds. The DGGE banding patterns of 16S rRNA gene and sequence analysis demonstrated that Oscillatoria acuminata and CFB (Cytophaga-Flavobacterium-Bacteroides) group bacterium appeared in the treated pond, and the control pond was dominated by Synechococcus sp. and Aphanizomenon flos-aquae. Especially, Pseudanabaena sp. dominated during the ultrasonic cessation in the treated pond. The DGGE profiles of 18S rRNA gene and sequence analysis showed that the treated pond was dominated by Chlamydomonas reinhardtii and the control pond by C. reinhardtii and Pteromonas protracta. In conclusion, the ultrasonication affected the reduced growth of cyanobacteria, particularly Pseudanabaena.