• Korean Journal of Environmental Biology
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• v.24 no.2 s.62
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• pp.147-154
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• 2006

Effects of water temperature, salinity and irradiance on the growth of toxic dinoflagellate Alexandrium catenella (AlCt-01) were investigated, which was isolated from Jinhae Bay, Korea. The maximum growth of A. catenella strain was obtained at $150{\mu}E\;m^{-2}s^{-1}$. The ranges of temperature and salinity for the growth of the strain were $15\sim25^{\circ}C$ and $20\sim34$ PSU. The maximum growth rate of A. catenella determined was $0.45d^{-1}$ at $20^{\circ}C$, 30 PSU and $150{\mu}E\;m^{-2}s^{-1}$ We also examined the Se and Fe effects on the toxic dinoflagellate A. catenella in optimal growth conditions. As Fe concentration of medium increased from 0 to $11.7{\mu}M$, growth rate of A. catenella increased and the maximum growth rate(k=0.48 $d^{-1}$) was obtained at $11.7{\mu}M$ of Fe cone. Growth of A. catenella were stimulated at> 1nM of Se.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.1
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• pp.119-126
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• 2021

In this study, the variability in paralytic shellfish poisoning (PSP) by the toxic dinoflagellate Alexandrium catenella (Group I) was analyzed under a variety of water temperatures and salinities. This dinoflagellate experienced optimum growth at temperatures and salinities of 20~30℃ and 20~30 psu, respectively. These findings indicate that A. catenella is an eurythermal and euryhaline organism. High toxin contents and toxicities were observed at low temperatures (10 and 15℃), where they were associated with low growth rates; salinity did not have any significant impact on toxicity parameters. Therefore, it is likely that A. catenaella contributes to the rapid intoxication of commercial bivalve when temperatures are ≤15℃. To better estimate PSP caused by A. catenalla, we suggest that the influence of various environmental factors controlling PSP should persist with other A. catenella stains and commercial bivalves.

• Journal of the Korean Society for Marine Environment & Energy
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• v.16 no.1
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• pp.25-35
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• 2013

Dominance and survival strategy of toxic dinoflagellate Alexandrium tamarense and A. catenella under the dissolved inorganic nitrogen (DIN) limited conditions were examined in the laboratory and field observations. In Masan Bay, DIN was limiting factor for growth of phytoplankton during spring to early summer when Alexandrium spp. have been observed. They have a disadvantageous position compared with diatoms because Ks of nitrate calculated from growth kinetics experiment of A. tamarense and A. catenella was higher than diatoms. However, A. tamarense and A. catenella were able to grow using dissolved organic nitrogen (DON) compounds such as urea and amino acids as well as DIN. Therefore, DON utilization of A. tamarense, A. catenella might contribute to not only their population growth but also dominance and interspecific competition in the DIN-limited conditions in Masan Bay.

• Journal of the korean society of oceanography
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• v.39 no.3
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• pp.163-171
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• 2004

Sequences of the large subunit ribosomal (LSD) rDNA D1-D2 region of Alexandrium catenella(=A. sp. cf. catenella) and A. tamarense isolates, which were collected along the Korea coasts, were analyzed to understand their phylogenetic relationships and geographical distributions. All A. catenella and A. tamarense isolates belonged to the A. tamarense/catenella/fundyense complex and were grouped with the North American and temperate Asian ribotypes, respectively, regardless of the presence or absence of a ventral pore in the first apical plate. A consistent and peculiar characteristic that differentiated the Alexandrium isolates was amplification of a second PCR product with a lower molecular weight in addition to the predicted one; ten A. catenella isolates belonging to the temperate Asian ribotype yielded this additional PCR product. Sequence alignment revealed that the shorter PCR product resulted from an unusual large deletion of 87 bp in the LSD rDNA D1 domain. The North American and temperate Asian ribotypes were prevalent along the Korean coasts without geographical separation. Given the high genetic homogeneity among widely distributed Alexandrium populations, each ribotype appeared to be pandemic rather than to constitute a distinct regional population.

• Fisheries and Aquatic Sciences
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• v.12 no.3
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• pp.227-235
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• 2009

The marine toxic dinoflagellate Alexandrium catenella has been implicated in numerous paralytic shellfish poisoning (PSP) events in many countries. Due to difficulties in rapidly identifying A. catenella, field-based study of this species has been problematic. The present study developed a TaqMan format A. catenella-specific probe for real-time PCR assay (specific to Korean genotype) based on LSU rDNA sequence information for studying geographic and temporal distribution of the species in surface sediments and water columns of Jinhae Bay, Korea. The field survey from 2007 to 2008 revealed that A. catenella occurred in most seasons at low densities, mostly below 1 cell $mL^{-1}$, and was more abundant in spring (maximum cell density of 2 cells $mL^{-1}$) when shellfish exceed the quarantine toxin level for PSP toxins in Jinhae Bay.

• ALGAE
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• v.17 no.1
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• pp.11-19
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• 2002

Twenty-nine culture strains belonging to the genus Alexandrium Halim (Dinophyceae) were established from water column or sediments in Korea. Seventeen isolates were identified as A. tamarense (Lebour) Balech, eight isolates as A. sp. cf. catenella and one as A. catenella (Whedon et Kofoid) Balech according to the presence or absence of a ventral pore, the shape of the posterior sulcal plate and the sulcal width. Three isolates were unable to be identified due to considerable distortion of thecal plates and lack of enough materials, but typical of A. tamarense and/or A. catenella. The overall cell shape of A. tamarense was usually longer than wide. The posterior sulcal plate was definitely longer than wide dorsoventrally, and sulcus extended posteriorly without apparent widening. They were distributed in three major coasts of Korea. In contrast, the cell shape of A. sp.cf. catenella was generally anterior-posteriorly flattened. The transversal axis of the posterior sulcal plate was always longer than the longitudinal, or both axes were nearly equal in length. Its sulcus was broader than that of A. tamarense and widened in the direction of antapex about 1.5 times. This morphotype existed in nearshore and offshore waters of the southern Korea sea. One of A. catenella isolates from Jinhae Bay showed no conspicuous differences with A. sp. cf. catenella except for the consistent absence of a ventral pore.

• Fisheries and Aquatic Sciences
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• v.7 no.3
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• pp.130-135
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• 2004

The marine dinoflagellate genus Alexandrium, which produces PSP toxins, has a global distribution. As human-assisted dispersal of the species has been suggested, it is important to develop molecular tools to trace the dispersal pathway. To screen population-specific DNA sequences that differentiate Korean and Japanese A. catenella, we targeted the area downstream of the chloroplast psbA gene using PCR with population-specific DNA primers followed by RFLP (restriction fragment length polymorphism) analysis and sequencing. The RFLP patterns of the PCR products divided Korean and Japanese A. catenella regional isolates into three types: Korean, Japanese, and type CMC3, isolated from Korea. We sequenced the PCR products, but found no similar gene in a homology search. The molecular phylogeny inferred from the sequences separated the Korean and Japanese A. catenella strains, as did the RFLP patterns. However, the Japanese isolates included two slightly different sequences (types J and K), while the Korean sequence was the same as the Japanese K type. In addition, a unique sequence was found in the Korean strains CMC2 and CMC3. Population-specific PCR amplification with Japanese A. catenella type-specific PCR primers designed from the type J sequence yielded PCR products for Japanese strains only, showing that the unknown gene can be used for a population analysis of Korean and Japanese A. catenella.

• Korean Journal of Environmental Agriculture
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• v.31 no.2
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• pp.175-184
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• 2012

BACKGROUND: The aim of this study was to isolate and identify algicidal bacterium that tends to kill the toxic dinoflagellate Alexandrium catenella, and to determine the algicidal activity. METHODS AND RESULTS: Among of four algicidal bacteria isolated in this study, NH-12 isolate was the strongest algicidal activity against A. catenella. NH-12 isolate was identified on the basis of biochemical characteristics and analysis of 16S rRNA gene sequences. The isolate showed 97.67% homology with Pseudoalteromonas prydzensis ACAM $620^T$ (U85855), and was designated Pseudoalteromonas sp. NH-12. The optimal culture conditions of this isolate were $25^{\circ}C$, initial pH 8.0, and 3.0% (w/v) NaCl concentration. The algicidal activity of NH-12 was significantly increased to maximum value in the late of logarithmic phase of bacterial culture. As a result of 'cell culture insert' experiment, NH-12 is assumed to produce secondary metabolites, as an indirect attacker. When 10% culture filtrate of NH-12 was applied to A. catenella, over 99% of algal cells were destroyed within 24 h. In addition, the killing effects were increased in dose and time dependent manners. CONCLUSION(S): Taken together, our results suggest that Pseudoalteromonas sp. NH-12 could be a candidate for controlling of toxic algal blooms.

• Journal of Environmental Science International
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• v.22 no.12
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• pp.1571-1577
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• 2013

The effects of irradiance on the growth of toxic dinoflagellates Alexandrium tamarense (Masan Bay strain) and Alexandrium catenella (Jinhae Bay strain) were investigated in the laboratory. At $15^{\circ}C$ and 30 psu for A. tamarense and $25^{\circ}C$ and 30 psu for A. catenella, the irradiance-growth curve showed the maximum growth rate (${\mu}_{max}$) of 0.31 $day^{-1}$ with half-saturation photon flux density (PFD) ($K_I$) of 44.53 ${\mu}molm^{-2}s^{-1}$, and a compensation PFD ($I_c$) was 20.67 ${\mu}molm^{-2}s^{-1}$ for A. tamarense, and ${\mu}_{max}$ of 0.38 $day^{-1}$ with $K_I$ of 59.53 ${\mu}molm^{-2}s^{-1}$, and $I_c$ was 40.80 ${\mu}molm^{-2}s^{-1}$ for A. catenella. The $I_c$ equated to a depth of 8~9 m from March to June for A. tamarense and 6~7 m from March to June for A. catenella. These responses suggested that irradiance at the depth near the middle layer in Masan Bay would provide favorable conditions for two species.

• Korean Journal of Environmental Agriculture
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• v.34 no.2
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• pp.139-148
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• 2015

BACKGROUND: The aim of this study was to isolate and identify algicidal bacterium that tends to kill the toxic dinoflagellate Alexandrium catenella, and to determine the algicidal activity and algicidal range of algicide. METHODS AND RESULTS: Among of algicidal bacteria isolated in this study, NH-3 isolate was the strongest algicidal activity against A. catenella. NH-3 isolate was identified on the basis of biochemical characteristics and analysis of 16S rRNA gene sequences. The NH-3 isolate showed over 99% homology with Arthrobacter oxydans, and was designated as Arthrobacter sp. NH-3. The optimal culture conditions were $25^{\circ}C$, initial pH 7.0, and 2.0% (w/v) NaCl concentration. The algicidal activity of Arthrobacter sp. NH-3 was significantly increased to maximum value in the late of logarithmic phase. Arthrobacter sp. NH-3 showed algicidal activity through indirect attack, which excreted active substance into the culture filtrate. When 10% culture filtrate of NH-3 was applied to A. catenella, 100% of algal cells were destroyed within 30 h. In addition, the algicidal activities were increased in dose and time dependent manners. The pure algicide was isolated from the ethyl acetate extract of the culture filtrate of NH-3 by using silica gel column chromatography and high performance liquid chromatography (HPLC). We investigated the algicidal activity of this algicide on the growth of harmful algal bloom (HAB) species, including A. catenella. As a result, it showed algicidal activity against several HAB species at a concentration of $100{\mu}g/mL$ and had a relatively wide host range. CONCLUSION: Taken together, our results suggest that Arthrobacter sp. NH-3 and its algicide could be a candidate for controlling of toxic and harmful algal blooms.