• Journal of Microbiology
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• v.45 no.3
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• pp.205-212
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• 2007

Anoxygenic photosynthesis, performed primarily by anoxygenic photosynthetic bacteria (APB), has been supposed to arise on Earth more than 3 billion years ago. The long established APB are distributed in almost every corner where light can reach. However, the relationship between APB phylogeny and source environments has been largely unexplored. Here we retrieved the pufM sequences and related source information of 89 pufM containing species from the public database. Phylogenetic analysis revealed that horizontal gene transfer (HGT) most likely occurred within 11 out of a total 21 pufM subgroups, not only among species within the same class but also among species of different phyla or subphyla. A clear source environment feature related phylogenetic distribution pattern was observed, with all species from oxic habitats and those from anoxic habitats clustering into independent subgroups, respectively. HGT among ancient APB and subsequent long term evolution and adaptation to separated niches may have contributed to the coupling of environment and pufM phylogeny.

• Journal of Species Research
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• v.10 no.4
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• pp.356-363
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• 2021

Heterotrophic nanoflagellates (HNFs, 2-20 ㎛ in size) are substantially capable of controlling bacterial abundance in aquatic environments, and microbial taxonomists have studied ecologically important and abundant HNFs for a long time. However, the classifications of HNFs have rarely been reported in Korea on the basis of morphology and 18S rDNA sequencing. Here, previously reported five HNFs from non-Korean habitats were isolated from Korean coastal seawater or intertidal sediments for the first time. Light microscopic observations and 18S rDNA phylogenetic trees revealed that the five isolated species were Cafeteria burkhardae strain PH003, Cafeteria graefeae strain UL001, Aplanochytrium minuta (formerly Labyrinthuloides minuta) strain PH004, Neobodo curvifilus strain KM017 (formerly Procryptobia sorokini), and Ancyromonas micra (formerly Planomonas micra) strain IG005. Being morphologically and phylogenetically indistinct from its closest species, all isolates from Korea were therefore regarded as identical species detected in other countries. Thus, this result indicates an expansion of known habitats that range from those of the five isolates in natural ecosystems on Earth.

• Journal of Korean Society of Disaster and Security
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• v.16 no.4
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• pp.109-121
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• 2023

Squr dikes in rivers can enhance various ecological environments, contributing to the improvement of the river's environmental functions. However, the alterations in flow caused by squr dikes not only enhance environmental functions but can also have adverse effects. Therefore, this study aimed to analyze the flow changes induced by the installation of squr dikes through flume experiments and assess their impact on fish habitats. Key factors in the fish habitat environment include flow velocity, turbulence kinetic energy, and recirculation zones. Among these, particular emphasis was placed on examining turbulence kinetic energy and recirculation zones. Experimental conditions were set by varying the interval and submergence of the squr dikes, resulting in a total of eight experimental cases. The results revealed that shorter interval and lower submergence of the squr dikes led to increased turbulence kinetic energy and recirculation zone sizes, significantly impacting fish habitats.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.6
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• pp.501-507
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• 2000

Distribution and habitat characteristics of Zostera (Zosteraceae) in the eastern coast of Korea were examined along with plant monohology, sediment composition and physicochemical factors of seawater from June 1998 to July 2000, The results showed that three species, Zostera marina, Z. asiatica and Z, caespitosa were found in specific habitats. The depth of habitat for Z. asiatica was deeper ($8.5{\~}15.0 m$) than that of Z. marina ($1.3{\~}5.6 m$) and Z. caespitosa ($3.2{\~}5.2 m$). Z. marina beds were observed at brackish-water, port and inner bay with the sediment type of sand or muddy sand. Habitats of Z. asiatica were restricted to the open bay with the sediment type of sand, Zostera have been described with regard to different growth forms of vegetation, flowering shoot and life history. Vegetation and flowering shoot length varied significantly with habitats; values ranged $66.8{\~}110.0 cm$ and $128.0{\~}217,8 cm$, respectively. Morphology of Z. marina varied with water depth and different substrates. Morphological characteristics of Z. asiatica showed a new phenotype at the deeper water depth. Vegetation and flowering shoots of Z. caespitosa were not significantly different between study sites (values ranged from 64.9 cm to 70.3 cm). Nutrient concentrations of seawater were higher at southern part than at middle part of the eastern coast of Korea. Distribution of Zostera in the eastern coast of Korea was dependent upon differences in water depth and habitat environments, by which affected the morphological differences were affected.

• Journal of Microbiology
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• v.45 no.4
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• pp.281-285
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• 2007

Cold environments, including polar and alpine regions, are colonized by a wide diversity of micro-organisms able to thrive at low temperatures. There is evidence of a wide range of metabolic activities in alpine cold ecosystems. Like polar microorganisms, alpine microorganisms playa key ecological role in their natural habitats for nutrient cycling, litter degradation, and many other processes. A number of studies have demonstrated the capacity of alpine microorganisms to degrade efficiently a wide range of hydrocarbons, including phenol, phenol-related compounds and petroleum hydrocarbons, and the feasibility of low-temperature bioremediation of European alpine soils by stimulating the degradation capacity of indigenous microorganisms has also been shown.

• Mycobiology
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• v.47 no.3
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• pp.261-272
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• 2019

Oomycetes are widely distributed in various environments, including desert and polar regions. Depending upon different habits and hosts, they have evolved with both saprophytic and pathogenic nutritional modes. Freshwater ecosystem is one of the most important habitats for members of oomycetes. Most studies on oomycete diversity, however, have been biased mostly towards terrestrial phytopathogenic species, rather than aquatic species, although their roles as saprophytes and parasites are essential for freshwater ecosystems. In this study, we isolated oomycete strains from soil sediment, algae, and decaying plant debris in freshwater streams of Korea. The strains were identified based on cultural and morphological characteristics, as well as molecular phylogenetic analyses of ITS rDNA, cox1, and cox2 mtDNA sequences. As a result, we discovered eight oomycete species previously unknown in Korea, namely Phytopythium chamaehyphon, Phytopythium litorale, Phytopythium vexans, Pythium diclinum, Pythium heterothallicum, Pythium inflatum, Pythium intermedium, and Pythium oopapillum. Diversity and ecology of freshwater oomycetes in Korea are poorly understood. This study could contribute to understand their distribution and ecological function in freshwater ecosystem.

• The Korean Journal of Mycology
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• v.49 no.3
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• pp.351-362
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• 2021

Penicillium is the most common fungal genus in various terrestrial and marine environments. The number of new and unrecorded Penicillium species from various substrates and habitats are continuously increasing. As part of a project to discover indigenous fungi in South Korea, three unrecorded Penicillium species were isolated from mudflats and seaweeds. Based on morphological characteristics and phylogenetic analyses of β-tubulin and calmodulin loci, they were identified as P. amaliae, P. infrabuccalum, and P. manginii. Here, we provide a detailed morphological description and sequence information of these previously unrecorded species.

• Mycobiology
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• v.50 no.6
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• pp.420-428
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• 2022

Plastic wastes have a negative impact on marine environments; however, they can be used as carbon sources and habitats by certain microbes. Microbes in the marine plastisphere can migrate worldwide through the ocean and cause serious environmental problems when they encounter suitable environments. Therefore, efforts to investigate the microbes inhabiting the marine plastisphere are increasing. In the present study, fungal strains were isolated from plastic wastes buried in Korean sea sands and mudflats and identified using molecular and morphological analyses. Five species were identified that were previously unrecorded from South Korea: Cladosporium funiculosum, Neosetophoma poaceicola, Neosetophoma rosigena, Parasarocladium gamsii, and Trichoderma fomiticola. Their molecular phylogenies and morphological characteristics are described in this study.

• Journal of Microbiology and Biotechnology
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• v.31 no.2
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• pp.240-249
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• 2021

Phenotypic plasticity is a rapid response mechanism that enables organisms to acclimate and survive in changing environments. The Chinese mitten crab (Eriocheir sinensis) survives and thrives in different and even introduced habitats, thereby indicating its high phenotypic plasticity. However, the underpinnings of the high plasticity of E. sinensis have not been comprehensively investigated. In this study, we conducted an integrated gut microbiome and muscle metabolome analysis on E. sinensis collected from three different environments, namely, an artificial pond, Yangcheng Lake, and Yangtze River, to uncover the mechanism of its high phenotypic plasticity. Our study presents three divergent gut microbiotas and muscle metabolic profiles that corresponded to the three environments. The composition and diversity of the core gut microbiota (Proteobacteria, Bacteroidetes, Tenericutes, and Firmicutes) varied among the different environments while the metabolites associated with amino acids, fatty acids, and terpene compounds displayed significantly different concentration levels. The results revealed that the gut microbiome community and muscle metabolome were significantly affected by the habitat environments. Our findings indicate the high phenotypic plasticity in terms of gut microbiome and muscle metabolome of E. sinensis when it faces environmental changes, which would also facilitate its acclimation and adaptation to diverse and even introduced environments.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.4
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• pp.462-472
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• 2023

We investigated the physio-chemical and geochemical parameters in the spraying shellfish aquacultures (Yeoja and Gangjin Bay) to establish the systematic strategy for effective environmental management. Spatial variation of each parameter showed partially significant difference (P<0.05) between Yeoja and Ganjin Bay, inferring the discriminative progress (i.e., accumulation and degradation) of the autochthonous organic matter within the aquaculture environments. We additionally integrated various properties (e.g., water/sediment quality, natural hazard, and biological health) which may affect the biological growth within the aquaculture habitats based on the biogeochemical cycles related to environmental components and aquaculture species. We used a screening approach (i.e., one out-all out; OOAO) which can permit the assessment of the health levels of aquaculture species, the scoring for other parameters (seawater, sediment, and natural hazard) as three levels (excellent, moderate and poor) depending on the complex interactive properties occurring in the aquaculture environments. Actual, discriminative scores obtained via our case studies may confirm that these stepwise processes are effectively evaluated for optimal health conditions within the aquaculture habitats. Thus, this approach may provide valuable insights for effective environmental management and sustainable growth of aquaculture operation.