• ALGAE
• /
• 제37권4호
• /
• pp.281-291
• /
• 2022

Quantifying the abundance of Chattonella species is necessary to effectively manage the threats from ichthyotoxic raphidophytes, which can cause large-scale mortality of aquacultured fish in temperate waters. The identification and cell counting of Chattonella species have been conducted primarily on living cells without fixation by light microscopy because routine fixatives do not retain their morphological features. Species belonging to the Chattonella marina complex, including C. marina and C. marina var. ovata, had high genetic similarities and the lack of clear morphological delimitations between the species. To estimate the abundance of C. marina complex in marine plankton samples, we developed a protocol based on the droplet digital polymerase chain reaction (ddPCR) assay, with C. marina complex-specific primers targeting the internal transcribed spacer (ITS) region of the rDNA. Cell abundance of the C. marina complex can be determined using the ITS copy number per cell, ranging from 25 ± 1 for C. marina to 112 ± 7 for C. marina var. ovata. There were no significant differences in ITS copies estimated by the ddPCR assay between environmental DNA samples from various localities spiked with the same number of cells of culture strains. This approach can be employed to improve the monitoring efficiency of various marine protists and to support the implementation of management for harmful algal blooms, which are difficult to analyze using microscopy alone.

• Membrane and Water Treatment
• /
• 제14권2호
• /
• pp.77-83
• /
• 2023

As a result of algal bloom, algal organic matters (AOMs) are rapidly increased in surface water. AOMs can act as precursors for the formation of harmful disinfection by-products (DBPs), which are serious problems in water treatment and human health. The main aim of this study is to characterize the formation of DBPs from AOMs produced by three different algae such as Oscillatoria sp., Anabaena sp., and Microcystis aeruginosa under different algal growth phases. In an effort to examine formation of DBPs during chlorination, chloroform (TCM), dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) were determined under various CT (product of disinfectant concentration and contact time, mg·min/L) values. Generally, the amounts of DBPs tended to increase with increasing CT values at the most growth phases. However, there was a significant difference between the amounts of DBPs produced by the three algal species at different growth phases. This result is likely due to the chemical composition variability of AOM from different algae at different growth phases. In addition, the effect of pre-ozonation on coagulation for the removal of AOMs from three algal species was investigated. The pre-ozonation had a positive effect on the coagulation/flocculation of AOMs.

• 한국습지학회지
• /
• 제25권4호
• /
• pp.267-273
• /
• 2023

조류는 생태계를 구성하는 중요한 요소이다. 그러나 남조류의 과도한 성장은 하천환경에 다양한 악영향을 발생시키고 규조류는 상수원과 정수장 공정관리에 영향을 미친다. 지속적이고 효율적인 조류 관리를 위해 조류 모니터링이 중요하다. 본 연구에서는 You Only Look Once (YOLO)의 최신 알고리즘 YOLO v8을 사용하여 조류경보제 기준에 사용하는 유해 남조류 4종과 정수처리공정에 영향이 큰 규조류 1종 총 5종의 이미지를 분류하는 이미지 분류모형을 구축하였다. 기본모형의 mAP는 64.4로 분석되었다. 모형의 학습에 사용된 원본 이미지에 회전, 확대, 축소를 수행하여 이미지의 다양성을 높인 5가지 모형을 구축하여 입력자료로 사용된 이미지의 구성에 따른 모형 성능의 변화를 비교하였다. 분석결과 회전, 확대, 축소를 모두 적용한 모형이 mAP 86.5로 가장 좋은 성능을 보이는 것을 확인하였다. 이미지의 회전만을 적용한 모형, 회전과 확대를 적용한 모형, 이미지의 회전과 축소만를 적용한 모형의 mAP는 각각 85.3, 82.3, 83.8로 분석되었다.

• 해양환경안전학회지
• /
• 제16권4호
• /
• pp.421-425
• /
• 2010

최근 지구온난화로 인한 수온상승과 해수면의 상승으로 인해 해양 생태계가 변화되고 있다고 보고되고 있다. 한반도 주변 해역에서도 수온과 해수면이 상승하고 플랑크톤의 종 조성이 변화되고 가시파래, 불가사리, 해파리 등의 유해 생물종의 출현 빈도가 증가되고 있고, 바다 사막화가 증가되는 등 해양 생태계의 변화로 어업활동이 어려워지고 어업생산량이 감소하여 어민 경제가 심각한 영향을 받고 있다. 본 보고서에서는 지구 온난화의 원인과 그 메커니즘을 소개하고, 지구 온난화에 따른 해양환경 변화와 해양 생태계에 미치는 영향과 그 대책에 관하여 보고하고자 하였다.

• 센서학회지
• /
• 제33권1호
• /
• pp.30-33
• /
• 2024

The occurrence of harmful algae on the coast of Korea has been a cause of damage to the aquaculture industry and deterioration of the coastal ecosystem environment. A method is required to predict their outbreak in real-time at the site. Therefore, this study attempted to develop a small hybrid optical sensor and real-time monitoring system based on LiDAR that can be used in the field and laboratory and can be applied to various platforms. FMS-L specifically suggested the amount of Chlorophyll a (Chl a) in the sample by measuring and analyzing the fluorescence emitted by the irradiating light. The accuracy of FMS-L was verified by measuring the concentrations of standard Chlorophyll a substances and Margalfidinium polykirkoids. In addition, the precision was verified by comparing the measurement results of FMS-L using commercial equipment Phyto-PAM-II. This equipment is compact and easy to move. Therefore, it can be easily applied to field surveys, allows short time measurements (10 s), and can be applied at a distance of 10 m from the measurement site.

• 한국물환경학회지
• /
• 제33권5호
• /
• pp.538-545
• /
• 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).

• 한국양식학회지
• /
• 제18권2호
• /
• pp.86-91
• /
• 2005

I. galbana, P. parvum 및 P. patelliferum 등 3종의 착편모조를 각각 먹이로서 급이 하면서 각각의 먹이에 따른 해산 요각류 T. japonicus의 nauplius 및 copepodid 유생의 개체수 증식 양상과 재포란 암컷의 개체수 변화 양상, 그리고 배양 도중 사망한 성체 암컷의 개체수를 서로 비교하였으며, 또한 각 계수일에 측정한 배 양수내의 먹이로서 급이한 3종의 착편모조의 세포수 변화 양상을 관찰하였다. 비교구로서 먹이를 전혀 공급하지 않은 실험구의 T. japonicus는 고압 멸균한 자연 해수만을 이용하여 배양하였다. 실험 결과 3종의 착편모조 중 I. galbana를 급이한 경우에는 T. japonicus의 정상적인 유생 발생과 함께 적극적인 I. galbana의 섭이를 관찰할 수 있었으나, P. parvum과 P. patelliferum을 급이한 경우에는 갓 부화한 nauplius 유생이 거의 100% 사망하였고 암컷 성체의 재포란율 또한 거의 0 (zero)임이 관찰되었다. 더욱이 15일간의 실험기간 중에 암컷 성체의 사망을 관찰하였다. 위와 같은 일련의 실험 결과로 볼 때, 독성을 가지며 적조의 원인종으로 알려진 착편모조 P. parvum과 P. patelliferum은 요각류 T. japonicus에 대해서 유해함을 알 수 있었다.

• 한국잡초학회지
• /
• 제30권3호
• /
• pp.233-242
• /
• 2010

본 연구에서는 1-alkyl-3-methylimidazolium chloride계 이온성 액체를 가지고 수생태계에서의 유해조류 방제제로서의 사용 가능성 및 활용시 예상되는 문제점 등을 알아보기 위하여 5종의 녹조류, 4종의 남조류, 1종의 규조류를 대상으로 이들의 생육에 미치는 이온성 액체의 선택적 영향을 검토해 보고자 실시하였다. 이온성 액체의 alkyl group 탄소수에 따라 활성이 달리 나타났는바, butyl < octy l< dodecyl 순으로 탄소수 길이가 길수록 살조활성이 증가되는 경향이었다. 공시된 조류종 전체를 비교해 보았을 때, Stephanodiscus hantzschii f. tenuis, Oscillatoria tenuis, Spirulina pratensis가 1-dodecyl-3-methylimidazolium chloride (MAIC12)에 민감한 생육억제 반응을 보이며 그 다음은 Microcystis aeruginosa이었고, 나머지 조류 종은 상대적으로 덜 민감하였다. 선택성 정도는 80% 억제농도를 기준하여 검토해 보았을 때 대략 10-20배 정도였다. 한편 자연상태와 비슷한 조건(온실조건의 퇴적물 존재)에서 이온성 액체가 수중에 처리되었을 때의 살조활성 지속성을 조사하였다. 그 결과 MAIC8 $1.0{\mu}g\;mL^{-1}$ 농도에서는 처리후 6일까지 생장이 중지되었다가 9일째에는 조류가 약간 발생하였으며 이후 생장이 뚜렷하게 증가하는 경향으로서 20일째에는 엽록소 함량이 $264.4{\mu}g\;L^{-1}$로서 무처리 대비 58.2% 생장을 나타냈다. MAIC12의 경우는 MAIC8 보다 약 5배 높은 활성을 나타내는 경향으로서 $0.2{\mu}g\;mL^{-1}$ 농도로 처리했을 때 처리후 6일까지 조류발생이 전혀 없었다가 9일째에는 조류가 약간 번식하였으며 이후 생장이 비교적 뚜렷하게 증가하여 20일째에는 엽록소 함량이 $251.2{\mu}g\;L^{-1}$로서 무처리 대비 55.2% 생장을 나타냈다. 결론적으로 1-alkyl-3-methylimidazolium chloride계 이온성 액체는 살조활성 특성 측면에서 볼 때는 우수한 효능, 선택적 살조활성 및 효과 지속성으로 인해 수생태계에서의 유해조류 선택적 방제제로서 사용될 수 있을 것 같았으나, 화합물 분해 측면에서 볼 때는 상대적으로 난분해성 특성을 가져 환경친화적으로 사용하기에는 개선될 필요성이 있는 것 같았다.

• Journal of Microbiology and Biotechnology
• /
• 제18권10호
• /
• pp.1621-1629
• /
• 2008

Harmful algal blooms (HABs), commonly called red tides, are caused by some toxic phytoplanktons, and have made massive economic losses as well as marine environmental disturbances. As an effective and environment-friendly strategy to control HAB outbreaks, biological methods using marine bacteria capable of killing the harmful algae or algicidal extracellular compounds from them have been given attention. A new member of the $\gamma$-Proteobacteria, Hahella chejuensis KCTC 2396, was originally isolated from the Korean seashore for its ability to secrete industrially useful polysaccharides, and was characterized to produce a red pigment. This pigment later was identified as an alkaloid compound, prodigiosin. During the past several decades, prodigiosin has been extensively studied for its medical potential as immunosuppressants and antitumor agents, owing to its antibiotic and cytotoxic activities. The lytic activity of this marvelous molecule against Cochlodinium polykrikoides cells at very low concentrations ($\sim$l ppb) was serendipitously detected, making H. chejuensis a strong candidate among the biological agents for HAB control. This review provides a brief overview of algicidal marine bacteria and their products, and describes in detail the algicidal characteristics, biosynthetic process, and genetic regulation of prodigiosin as a model among the compounds active against red-tide organisms from the biochemical and genetic viewpoints.

• 환경생물
• /
• 제38권3호
• /
• pp.424-432
• /
• 2020

The present study aimed to analyze the metaproteome of the microbial community comprising harmful algal bloom (HAB) in the Daechung reservoir, Korea. HAB samples located at GPS coordinates of 36°29'N latitude and 127°28'E longitude were harvested in October 2013. Microscopic observation of the HAB samples revealed red signals that were presumably caused by the autofluorescence of chlorophyll and phycocyanin in viable cyanobacteria. Metaproteomic analysis was performed by a gelbased shotgun proteomic method. Protein identification was conducted through a two-step analysis including a forward search strategy (FSS) (random search with the National Center for Biotechnology Information (NCBI), Cyanobase, and Phytozome), and a subsequent reverse search strategy (RSS) (additional Cyanobase search with a decoy database). The total number of proteins identified by the two-step analysis (FSS and RSS) was 1.8-fold higher than that by one-step analysis (FSS only). A total of 194 proteins were assigned to 12 cyanobacterial species (99 mol%) and one green algae species (1 mol%). Among the species identified, the toxic microcystin-producing Microcystis aeruginosa NIES-843 (62.3%) species was the most dominant. The largest functional category was proteins belonging to the energy category (39%), followed by metabolism (15%), and translation (12%). This study will be a good reference for monitoring ecological variations at the meta-protein level of aquatic microalgae for understanding HAB.