• Microbiology and Biotechnology Letters
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• v.45 no.3
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• pp.243-249
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• 2017

An agar-degrading bacterium, designated as the GNUM08123 strain, was isolated from samples of red algae collected from the Yongil Bay near East Sea, Korea. The isolated GNUM08123 strain was gram-negative, aerobic, motile, and beige-pigmented, with $C_{16:0}$ (25.9%) and summed feature 3 (comprising $C_{16:1}{\omega}7c/iso-C_{15:0}2-OH$, 34.4%) as its major cellular fatty acids. A similarity search based on the 16S rRNA gene sequence revealed that it belonged to class Gammaproteobacteria and shared 97.7% similarity with the type strain Vibrio chagasii $R-3712^T$. The DNA G+C content of strain $GNUM08123^T$ was 46.9 mol%. The major isoprenoid quinone was ubiquinone-8. The results of DNA-DNA relatedness and 16S rRNA sequence similarity analyses, in addition to its phenotypic and chemotaxonomic characteristics, suggest that strain GNUM08123 is a novel species within genus Vibrio, designated as Vibrio sp. GNUM08123. Agarase production by strain GNUM08123 was induced by agar and sucrose, but was repressed probably owing to carbon catabolite repression by glucose and maltose.

• Journal of Korean Society of Forest Science
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• v.24 no.1
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• pp.53-61
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• 1974

Pine forests existing in Hong-do island were examined as regarding such characteristics, tree form, needle length, branch diameter, bark colors, ratio of summer wood to springwood, location and number of resin canal and other measurements. Hong-do island, located the furthest west part of Korea, suports only Pinus densiflora but very few Pinus thunbergii, in fact the present authors could not find any black pine individuals at all through investigation. Checking 14 individual trees of red pine, more than age of 20, of the genetic contamination by black pine, in a certain degree, exist. Here, a very dense foliage type and a very sparse foliage type tree of red pine growing nearby was examined and the unique fact was that each of those type has only one (average number 1.3) accessory resin canal, while other trees have three as minimum or more. The present authors thought this island had not been covered by any Pinus thunbergii but by Pinus densiflora. It was thought that Pinus thunbergii stands grown along the sea-coast of Korean Peninsula are pollen donors to this island.

• ALGAE
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• v.21 no.3
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• pp.311-316
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• 2006

The effects of light quality and irradiance on the growth of Cochlodinium polykrikoides were investigated in the laboratory. At 25°C and 30 psu the irradiance-growth curve was described as μ = 0.34 (I-9.76)/(I+12.5), (r=0.98). This suggests half-saturation photon flux density (PFD) (Ks) of 32.0 μmol photons m–2 s–1, and a compensation PFD (Ic) of 9.76 μmol photons m–2 s–1. Because the Ic equates to a depth of ca. 15.4 m, these responses suggest that irradiance at the depth around and below the thermocline in Yeosuhae Bay would provide favorable conditions for C. polykrikoides. Photoinhibition did not occur at 300 μmol photons m–2 s–1, which was the maximum irradiance used in this study. Blue (450 nm), yellow (590 nm) and red (650 nm) light had different effects on the growth of C. polykrikoides: it grew well under blue light, but not under yellow light. This implies that C. polykrikoides is more likely to cause an outbreak of red tide in the open sea where blue-green wavelengths predominate, rather than in enclosed water bodies where suspended particles absorb most of the blue wavelengths, and yellow-orange wavelengths predominate.

• ALGAE
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• v.35 no.2
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• pp.145-155
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• 2020

Specimens of red algae corresponding to the peyssonnelioid genus Sonderophycus were collected at Kure Atoll, Hawai'i, at a depth range of 88-94 m depth during mesophotic surveys of the Papahānaumokuākea Marine National Monument, Hawaiian Islands, and were analyzed using morphological and molecular approaches. Analyses of mitochondrial cytochrome oxidase subunit 1 and chloroplast rbcL DNA sequences demonstrated that the Hawaiian specimens were identical to one another yet distinct from the three other species currently recognized within the genus (S. capensis [Montagne] M. J. Wynne, S. coriaceus [Womersley & Sinkora] M. J. Wynne, and S. fervens Dixon), as well as the likely congener, Peyssonnelia caulifera Okamura, and are proposed here as a new species: Sonderophycus copusii A. R. Sherwood. Sonderophycus copusii is morphologically distinct from other members of the genus by the following combination of characters: the presence of occasional secondary perithallial growth, emergence of rhizoids from the hypobasal cuticle at a strongly acute angle, a lack of horizontally directed filaments in the lower perithallus, and the lack of a stipe. This is the first record of the genus Sonderophycus in the Hawaiian Islands. Sonderophycus copusii was documented as a dominant member of the algal community at Kure Atoll, and thus may play a significant ecological role in the deep-water benthic community of Kure Atoll, along the lines of reports of deep water peyssonnelioid beds in the Mediterranean, Red Sea, and Caribbean. This study further highlights the unexplored diversity of the Peyssonneliales in Hawai'i, and emphasizes more generally the degree of as yet undiscovered biodiversity of algae at mesophotic depths.

• Microbiology and Biotechnology Letters
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• v.41 no.1
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• pp.8-16
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• 2013

An agar-hydrolyzing marine bacterium, strain GNUM08120, was isolated from Sargassum fulvellum collected from Yeongil bay of East Sea of Korea. The isolate was Gram-negative, aerobic, motile with single polar flagellum, and grew at 1-10% NaCl, pH 5.0-8.0, and $15-37^{\circ}C$. G+C content and the predominant respiratory quinone were 46.13 mol% and Q-8, respectively. The major cellular fatty acids were Summed feature 3 (24.5%), $C_{16:0}$ (21.7%), and $C_{18:1}{\omega}7c$ (12.5%). Based on 16S rRNA gene sequence similarity and DNA-DNA hybridization analyses, strain GNUM08120 was identified as a novel subspecies of Alteromonas macleodii, designated Alteromonas macleodii subsp. GNUM08120. Production of agarase by strain GNUM08120 was likely repressed by the effect of carbon catabolite repression caused by glucose. The crude agarase prepared from 12-h culture broth of strain GNUM08120 exhibited an optimum pH and temperature for agarase activity at 7.0 and $40^{\circ}C$, respectively. The crude enzyme produced (neo)agarobiose, (neo)agarotetraose, and (neo)agarohexaose as the hydrolyzed product of agarose.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.3 no.2
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• pp.90-93
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• 1998

Cultured isolates of Prorocentrum minimum, P. micans, P. triestinum, P. balticum, Gymnodinium sanguineum, Alexandrium catenella, Scrippsiella trochoidea, and Heterosigma akashiwo from red tides in southern coast of Korea were phylogenetically compared on the basis of their 24S rRNA genes. For each isolate approximately 700 bp of 24S rDNA, encompassing D1 and D2 hypervariable domains, was amplified using the polymerase chain reaction and sequenced. The sequences were aligned with those reported in Genbank by using ClustalW program and phylogenetic tree was generated to show that morphospecies designations in the Alexandrium and Prorocentrum species are congruent with terminal taxa defined by phylogenetic analysis of the 24S rRNA fragment. Our results suggest that the molecular phylogeny approach could facilitate identification of domestic dinoflagellates which have ambiguous morphologies.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.6
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• pp.716-722
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• 2003

This study determined the optimum dosage for coagulation reactions of red tide organisms (RTO) using a combination of ignited oyster shell powder (10sp) and loess and examined the electrokinetic and rheological characteristics of their flocs. Two kinds of RTO, Cylindrotheca closterium and Skeletonema costatum, were sampled in Masan Bay and cultured in the laboratory. Coagulation experiments were conducted using various concentrations of IOSP, loess, IOSP+1oess, RTO, and a jar tester RTO cell numbers were counted for both the supernatant and RTO culture solution. The removal rates increased rapidly with increasing IOSP concentrations up to 50 mg/L and loess concentrations up to 800 mg/L. A removal rate of $100\%$ was reached at 400 mg/L of IOSP and 6,400 mg/L of loess. The highest increment $(16.7\%)$ of the rates of coagulation reaction occurred using both IOSP and loess (50+200 mg/L) in comparison with IOSP alone. The rate of coagulation reaction using both IOSP and loess (50+200 mg/L), $90.6\%,$ was similar to employing either IOSP of 150 mg/L or loess of 3,200 mg/L. All of the coagulation liquids for RTO, IOSP (200 mg/L), loess (200 ma/L), and IOSP+1oess (200+200 mg/L) revealed non-Newtonian fluid properties and therefore their shear rate vs. shear stress curves were non-linear. The coagulation liquids revealed elastic body properties at a lower shear rate increasing in the following order: RTO, IOSP (200 mg/L), loess (200 mg/L), and IOSP+1oess (200+200 mg/L. IOSP+1oess (200+200 mg/L) especially demonstrated plastic flow properties at a lower shear rate.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.6
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• pp.1007-1016
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• 2021

This study examined the characteristics and seasonal distribution patterns of subtidal marine algal communities along the east coast of Korea, from 2016 to 2017, and recorded the coverage ratio (%) by the algal type. During the study period, 134 marine algae species (16 green, 29 brown, and 89 red) were identified at the survey sites. The maximum number of species was observed at the Nagok site (70 species), and the minimum at the Gisamoon site (50 species). The total average biomass (dry weight) during the survey period was 66.22 g/m², including green algae (2.19 g/m²), brown algae (38.10 g/m²), and red algae (25.94 g/m²). The dominant seaweeds in the vertical distribution based on coverage rates (%) were Sargassum yezoense and Dictyopteris divaricata at the upper, Symphyocladia latiuscula and Undaria pinnatifida at the middle, and Agarum clathratum subsp. yakishiriense and Plocamium telfairiae at the lower sections of the distribution. Richness, evenness, and diversity index, calculated based on the biomass of the abundant species, were estimated to be 6.36, 0.55, and 1.98, respectively, over the entire sea area. Based on the evaluation of the environmental states using community indices, the ecological evaluation index (EEI-c) of subtidal marine algal communities along the east coast of Korea was marked as 'good-moderate'.

• Journal of Marine Life Science
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• v.7 no.2
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• pp.94-101
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• 2022

In this study, the marine medaka Oryzias javanicus was exposed to two concentrations of non-toxin-producing red tide dinoflagellate C. polykrikoides (1,000 and 2,000 cells ml^-1) for 96 h, and the time-course biochemical responses of antioxidant and immunity parameters were analyzed in the liver tissue. Significant ichthyotoxicity with increasing cell concentrations of C. polykrikoides and exposure period was observed for 96 h. Opercular respiratory rate was lowered in marine medaka exposed to 2,000 cells ml^-1 of C. polykrikoides. Intracellular malondialdehyde (MDA) content significantly elevated in response to both cell concentrations. In the case of glutathione (GSH) content, the levels were significantly elevated by 1,000 cells ml^-1 of C. polykrikoides, but the contents significantly depleted upon exposure to 2,000 cells ml^-1 of C. polykrikoides. Similarly, enzymatic activities of catalase (CAT) and superoxide dismutase (SOD) were increased by 1,000 cells ml^-1 of C. polykrikoides, whereas their activities were lowered by 2,000 cells ml^-1 of C. polykrikoides. Analysis of the two immunity parameters, alternative complement pathway and lysozyme, showed significantly lowered activities in 2,000 cells ml^-1 of C. polykrikoides-exposed liver tissue. These biochemical effects of C. polykrikoides on marine medaka would be helpful for understanding its acute effects in marine fish.

• Mycobiology
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• v.51 no.6
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• pp.401-409
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• 2023

Nigrospora (Xylariales, Apiosporaceae) consists of species of terrestrial plant endophytes and pathogens. Nigrospora has also been reported in marine environments such as mangroves, sea fans, and macroalgae. However, limited research has been conducted on Nigrospora associated with macroalgae. Here, we isolated Nigrospora species from three types of algae (brown, green, and red algae) from Korean islands (Chuja, Jeju, and Ulleung) based on phylogenetic analyses of multigenetic markers: the internal transcribed spacers (ITS), beta-tubulin (BenA), and translation elongation factor 1 (TEF1-α). A total of 17 Nigrospora strains were isolated from macroalgae and identified as nine distinct species. The majority of Nigrospora species (seven) were found on brown algae, followed by red algae (three), and then green algae (two). To our understanding, this study represents the first account of N. cooperae, N. covidalis, N. guilinensis, N. lacticolonia, N. osmanthi, N. pyriformis, and N. rubi occurring in marine environments. Additionally, this study provides the first report of the occurrence of N. cooperae, N. covidalis, N. guilinensis, N. lacticolonia, and N. osmanthi in South Korea. This study will provide valuable insights for future research exploring the functions of fungi in macroalgal communities.