Cyanobacterial harmful algal blooms (Cyano-HABs) are an international environmental problem that negatively affects the ecosystem as well as the safety of water resources by discharging cyanotoxins. In particular, the discharge of microcystins (MCs), a highly toxic substance, has been studied most actively, and various water treatment methods have been proposed for this purpose. In this paper, we reviewed adsorption technology, which is recognized as the most feasible, economical, and efficient method among suggested treatment methods for removing MCs. Activated carbons (AC) are widely used adsorbents for MCs removal, and excellent MCs adsorption performance has been reported. Research on alternative adsorption materials for AC such as biochar and biosorbents has been conducted, however, their performance was lower compared to activated carbon. The impacts of adsorbent properties (characteristics of pore surface chemistry) and environmental factors (solution pH, temperature, natural organic matter, and ionic strength) on the MCs adsorption performance were also discussed. In addition, toward effective control of MCs, the possibility of the direct removal of harmful cyanobacteria as well as the removal of dissolved MCs using adsorption strategy was examined. However, to fully utilize the adsorption for the removal of MCs, the application and optimization under actual environmental conditions are still required, thereby meeting the environmental and economic standards. From this study, crucial insights could be provided for the development and selection of effective adsorbent and subsequent adsorption processes for the removal of MCs from water resources.

Cyanobacterial resting cells, such as akinetes, are important seed cells for cyanobacteria’s early development and bloom. Due to their importance, various methods have been attempted to isolate resting cells present in the sediment. Ludox is a solution mainly used for cell separation in marine sediments, but finding an accurate method for use in freshwater is difficult. This study compared the two most commonly used Ludox methods (direct sediment treatment and sediment distilled water suspension treatment). Furthermore, we proposed a highly efficient method for isolating cyanobacterial resting cells and eDNA amplification from freshwater sediments. Most of the resting cells found in the sediment were akinete to the Nostocale and were similar to those of Dolichospermum, Cylindrospermum, and Aphanizomenon. Twenty times more akinetes were found in the conical tube column using the sediment that had no treatment than in the sample treated by suspending the sediment in distilled water. Akinete separated through Ludox were mainly spread over the upper and lower layers in the column rather than concentrated at a specific depth in the column layer. The mibC, Geo, and 16S rDNA genes were successfully amplified using the sediment directly in the sample. However, the amplification products of all genes were not found in the sample in which the sediment was suspended in distilled water. Therefore, 5 g to 10 g of sediment is used without pretreatment when isolating cyanobacterial resting cells from freshwater sediment. Cell isolation and gene amplification efficiency are high when four times the volume of Ludox is added. The Ludox treatment method presented in this study isolates cyanobacterial resting cells in freshwater sediment, and the same efficiency may not appear in other biotas. Therefore, to apply Ludox to the separation of other biotas, it is necessary to conduct a pre-experiment to determine the sediment pretreatment method and the water layer where the target organism exists.

Targeting Microcystin (MC), which is most abundantly detected in the North-Han River water area, we analyzed the relationship between the MC biosynthesis gene (mcyA gene), cyanobacteria cell density, and MC concentration, derived an RNA-MC conversion formula, and derived the cyanobacteria. The concentration of MC present in cells was predicted. In the North-Han River waters, the mcyA gene was found mainly at downstream sites of the North-Han River after Muk-Hyeon Stream junction, and higher copy numbers were found on average than other sites. In the Uiam Lake waters upstream of the North-Han River, the mcyA gene copy number increased at the Kong-Ji Stream point, and after September, the mcyA gene copy number decreased throughout the North-Han River waters. The expression of the mcyA gene was concentrated in the short period of summer due to the spatio-temporal difference between upstream and downstream water bodies. The mcyA gene expression level was not only highly correlated with MC concentration, but also correlated with the cell density of Microcystis aeruginosa and Dolichospermum circinale, which are known to biosynthesize MC. Six conversion formulas derived based on the RNA-MC relationship showed statistical significance (p<0.05) and exhibited high correlation coefficients (r) of 0.9 or higher. The expression level of MC biosynthesis gene present in eRNA determines the synthesis of cyanotoxin substances in water, quickly quantifies gene activity, and can be fully utilized for early warning of MC development.

Biological phosphorus removal is accomplished by exposing PAO(phosphorus accumulating organisms) to anaerobic-aerobic conversion conditions. In the anaerobic condition, PAO synthesize PHB(polyhydroxybutyrate) and simultaneously hydrolysis of poly-p resulting phosphorus(Pi) release. In aerobic condition, PAO uptake phosphorus(Pi) more than they have released. In this study, cyanobacteria Synechococcus sp., which is known to be able to synthesize PHB like PAO, was exposed to anaerobic-aerobic conversion. If Synechococcus sp. can remove excess phosphorus by the same mechanism as PAO, synergistic effects can occur through photosynthesis. Moreover, Synechococcus sp. is known to be capable of synthesizing PHB using inorganic carbon as well as organic carbon, so even if the available capacity of organic carbon decreases, it was expected to show stable phosphorus removal efficiency. In 6 hours of anaerobic condition, phosphorus release occurred in both inorganic and organic carbon conditions but SPRR(specific phosphorus release rate) of both conditions was 10 mg-P/g-MLSS/day, which was significantly lower than that of PAO. When converting to aerobic conditions, SPUR(specific phosphorus uptake rate) was about 9 mg-P/g-MLSS/day in both conditions, showing a higher uptake rate than the control condition showing SPUR of 6.4 mg-P/g-MLSS/day. But there was no difference in terms of the total amount of removal. According to this study, at least, it seems to be inappropriate to apply Synechococcus sp. to luxury uptake process for phosphorus removal.

본 연구는 2005년부터 2018년까지 14년간 주암호에서 출현한 남조류의 천이 양상을 분석하여, 남조류에 영향을 미친 주요 환경요인과의 관계를 파악하고자 연구를 수행하였다. 특히 2012년 이후 유해남조류 (Harmful algae) 출현량 급감의 원인을 파악하고자 하였다. 조사기간 동안 두 지점의 유해남조류 현존량은 주암댐: 10~24,891 cells mL-1, 신평: 13~26,043 cells mL-1의 범위로 출현하였다. 전반기 시기 두 지점의 평균 현존량은 각각 2,575 cells mL-1, 2,557 cells mL-1로, 이는 후반기 시기 평균 현존량 (42 cells mL- 1, 82 cells mL-1)에 비해 약 60배, 30배의 큰 세포수 차이를 보였다. 남조류가 상대적으로 많이 출현하는 여름 시기 (6~9월)를 대상으로 상관분석을 실시한 결과, 유해남조류는 TN, 방류량, 저수량과 양의 상관관계를 보였고, 전기전도도와는 음의 상관관계를 보였다. t-검정 결과 TN, EC, 체류시간의 유의미한 차이를 확인하였다. 특히 TN은 0.566~1.292 mg L-1의 범위로 평균 0.862 mg L-1로 보였다. 전반기, 후반기 평균 TN은 전반기 0.912 mg L-1, 후반기 0.811 mg L-1로 감소하였다. 또한 유의확률은 다소 떨어지지만, TP의 경우 평균 차이는 없으나 표준편차가 비교적 큰 차이를 보여 변동성이 큼을 알 수 있었다. 강우량이 집중된 여름 (6~9월) 시기의 전반기와 후반기 강우량 감소하는 패턴이 원인인 것으로 판단된다 (전반기 263.3 mm, 후반기 219.9 mm). 즉, 전반기에 비해 강우량은 감소 하였으며, 이로 인해 TP의 변동성이 감소되었다고 판단된다. TP의 변동성의 감소로 인해 전반기에 남조류의 luxury consumption이 가능하여 남조류의 성장률이 높았을 것으로 추측된다. 따라서 주암호 유해남조류 감소 원인은 강우량의 감소로 인한 영양염의 감소 (TN) 및 변동성의 감소 (TP)의 결과로 사료된다.

국내 금강수계의 하구역에 위치한 하제항 암벽으로부터 기중성 남세균이 채집되어, 단조류 배양되었다. 2개의 남세균 배양주로부터 형태적 형질과 TEM에 의한 세포 미세구조 특징을 관찰하였다. 또한 16S rDNA 염기서열을 규명하여 BLAST 검색, 염기서열 유사도, 유전거리 및 계통 분석을 실시하였다. 국내 배양주는 Wilmottia murrayi와 계통학적으로 동일한 clade를 형성하였고, 99% 이상의 유사도를 나타냈다. TEM을 통한 세포 미세구조는 틸라코이드가 여러겹으로 세포막 주변에 분포하는 특징을 나타냄으로써 Coleofasciculaceae과의 특징과 일치하였다. 이상의 결과를 통해 W. murrayi를 국내 미기록속 및 미기록종으로 보고하였다.

Samples were collected from planktonic habitats of the fresh and brackish waters in Korea from August 2016 to May 2018. As a result, three genera and nine species were newly recorded in Korea. The unrecorded indigenous genera were Anathece, Chondrocystis and Geminocystis, and nine species were Anabaenopsis arnoldii, Anathece smithii, Chondrocystis dermochroa, Coelosphaerium aerugineum, Eucapsis microscopica, Geminocystis herdmanii, Microcystis panniformis, Synechococcus nidulans and Woronichinia karelica. Anathece smithii, Coelosphaerium aerugineum, Eucapsis microscopica, Microcystis panniformis and Synechococcus nidulans had been reported to inhabit freshwater, but these were found in brackish water in this study. Microcystis panniformis, which is a potential genus for causing green-tide, is taxonomically valuable in Korea.

Samples were collected from benthic and subaerophytic habitats of fresh and brackish water in Korea from April 2017 to April 2018. Accordingly, three genera and seven species were newly recorded in Korea. Three unrecorded genera were Cephalothrix, Cyanophanon and Toxifilum, and seven species were Anagnostidinema pseudacutissimum, Calothrix elenkinii, Cephalothrix komarekiana, Cyanophanon mirabile, Cyanosarcina chroococcoides, Leptolyngbya ectocarpi and Toxifilum mysidocida. Anagnostidinema pseudacutissimum and Cephalothrix komarekiana had been previously reported to inhabit freshwater, but these were found to be present in brackish water during the period of the present study. Also, Cyanosarcina chroococcoides previously reported to inhabit moorland waters and swamps, were found to be present in subaerophytic habitat.

Although physiological and ecological characteristics of cyanobacteria have been studied extensively for decades, unknown areas still remain greater than the already known. Recently, the development of omics techniques based on molecular biology has made it possible to view the ecosystem from a new and holistic perspective. The molecular mechanism of toxin production is being widely investigated, by comparative genomics and the transcriptomic studies. Biological interaction between bacteria and cyanobacteria is also explored: how their interactions and genetic biodiversity change depending on seasons and environmental factors, and how these interactions finally affect each component of ecosystem. Bioinformatics techniques have combined with ecoinformatics and omics data, enabling us to understand the underlying complex mechanisms of ecosystems. Particularly omics started to provide a whole picture of biological responses, occurring from all layers of hierarchical processes from DNA to metabolites. The expectation is growing further that algal blooms could be controlled more effectively in the near future. And an important insight for the successful bloom control would come from a novel blueprint drawn by omics studies.

Samples were collected between August 2016 and May 2017 at Sangju-si, Gyeongsangbuk- do, Jeju-do, and Uljin-gun, Gangwon-do. As a result, one genus and six species were newly recorded in Korea. The unrecorded indigenous genus was Borzia, and the six species were Anagnostidinema acutissimum, Komvophoron bourrellyi, Hydrocoleum stankovicii, Borzia trilocularis, Phormidium tinctorium and Pseudanabaena lohchoides. Phormidium tinctorium and Pseudanabaena lohchoides had been reported to inhabit freshwater, but in this study, these were found in brackish water. It had also been reported that B. trilocularis trichomes are composed of up to 8 cells, but in this study, a maximum of 10 cells was observed.

To evaluate the relationship between dynamics of cyanobacteria and odorous compounds, a monthly monitoring of water quality and phytoplankton were conducted at the three serial lakes (Lake Ui-am, Lake Cheong-pyeong and Lake Pal-dang) in the North Han River for 11 times from May 2014 to March 2015. In the three serial lakes, phytoplankton communities showed that seasonal changes in Bacillariophyceae- Cyanophyceae-Bacillariophyceae. Anabaena and Pseudanabaena were dominant species in August and September 2014. At the same time the odors (Geosmin, 2-MIB) were also detected with high concentration. Relationship between environmental factors and cyanobacterial abundance showed a significant correlation with Anabaena circinalis and geosmin (r=0.983, p<0.01). In the case of Pseudanabaena limnetica showed a significant correlation of total nitrogen (r=0.685, p<0.01) and NO3-N (r=0.723, p<0.01). In addition, similarly Pseudanabaena limnetica and 2-MIB (r=0.717, p<0.01) was high. The odorous compounds appeared in the North Han River water were considered to be a direct relationship with cyanobacteria.

본 연구는 초음파의 주파수별 노출 시간이 녹조현상을 일으키는 Microcystis sp.의 군체에 미치는 영향을 알아보고자 하였다. 각 조사 지점 내의 녹조 생물은 남조강(Cyanophyceae)인 Microcystis sp.가 전체 조류의 약 99.5%를 차지하였다. 초음파의 노출에 따른 녹조류의 chlorophyll-a 농도를 분석해보면 노출시간이 길어짐에 따라 점차적으로 감소하였으며, 특히 70 kHz의 주파수 영역에서 녹조 생물이 세포분열을 통한 생물량의 증가를 억제하는 데 효과적인 것으로 조사되었다. 초음파에 노출되기 전 Microcystis sp.는 단세포가 점액성 물질에 조밀하게 쌓여 있는 군체의 형태로 관찰되었으나 70 kHz 초음파에 노출된 후 Microcystis sp.의 군체의 결속이 약화되고 세포가 군체에서 떨어져 나가는 것으로 나타났다. 또한 초음파는 동∙식물성 플랑크톤의 형태적 변화와 운동성에 영향을 미치지 않아 다른 수중 미생물에는 부정적인 영향을 주지 않는 것으로 확인되었다. 따라서 초음파는 Microcystis sp.의 군체와 형태적 변화를 유발하고 세포를 파괴시켜 녹조현상을 일으키는 조류의 생물량을 감소시키는 데 효과적으로 작용할 것으로 사료된다.

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 Kützing and T. variabilis (Kützing ex Bornet et Flahault) Komárek 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.

남조류에 의한 수화가 발생한 과림, 도창, 물왕 저수지로부터 시료를 채수 하여 남조류 분해 균주의 분리를 시도하였다. BG-11배지에 Anabaena cylindrica를 double layer method를 이용하여 남조류 lawn을 만들어 각각의 시료를 100μl씩 smearing하였다. 28˚C 3,000 Lux light chamber에서 13일간 배양하여 도창 저수지 시료를 접종한 Anabaena cylindrica

1996년과 1997년에 남조류가 발생한 여러 호수에서 microcystin-RR, microcystin-LR, microcystin-YR의 함량을 정량하였고, 쥐를 이용하여 독성 검사를 실시하였다. 소양호를 제외한 모든 호수에서 Microcystis속의 종 들이 우점하였으며 전체 남조류 발생 호수의 시료에 대한 독소 검출의 빈도는 85%이였다. 조류세포내 총 microcystin의 함량은 0.29~2.61 mg/g이었으며 수중의 농도로 환산하면 0.4~21.6 μg/l이였다. 독소 함량은 1996년 보다 1997년에 높았고, 세 종류의 microcystin중 microcystin-RR이 가장 많이 검출되었다. 각 시료의 쥐에 대한 LD50은 총 microcystin함량과 LD50의 상관관계식에 의해 계산되었다. 화학분석에 의해 microcystin이 검출된 시료의 추출물이 주입되었을 때 쥐의 치사효과가 나타난 것으로 보아 microcystin 함량의 화학분석결 과와 bioassay 결과는 잘 일치하는 것으로 보이며, 영랑호 시료를 대상으로 실측한 LD50은 경험식으로 계산된 LD50과 일치하였다. 대상호수의 LD50은 27~338 mg/kg 의 범위로서 국내외에서 보고된 것에 비하여 높은 독성을 나타냈다.

본 연구는 대청호에서 식물플랑크톤의 우점종 변화양상과 취기물질 생산종을 밝히기 위해 1998년 5월부터 11월까지 월별로 2개 정점(추동, 회남교)을 선정하여 이 화학적 수질과 식물플랑크톤의 분포를 조사하였으며, 대표적 취기물질인 geosmin과 2-methylisoborneol (MIB) 의 분포를 purge & trap concentrator가 장착된 gas chromatograph로 조사하였다. 조사기간에 나타난 식물 플랑크톤의 계절적 분포는 수온, pH 및 총질소/총인 등과 상관관계가 있는 것으로 분석되었다. 조사된 식물플랑크톤 중에서 cyanobacteria가 평균 54% (세포수 기준)의 우점을 나타낸 추동수역(정점 1)에서는 geosmin이 7 월, 8월 하순에 세포건량기준으로 각기 1.1 ng/mg, 18.1 ng/mg이 검출되었고, 63% 이상의 우점을 보인 회남교수 역(정점 2)에서는 geosmin이 7월, 8월 하순에 각각 0.7 ng/mg 및 69.8 ng/mg, MIB가 7월 하순에 0.6 ng/mg 검 출되었다. 따라서 geosmin과 MIB는 조사기간중 cyanobacteria가 우점하게 되는 7월, 8월에 주로 Anabaena에 의해 생산되는 것으로 판단된다.