• Journal of Species Research
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• v.7 no.3
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• pp.187-192
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• 2018

During a comprehensive study of indigenous prokaryotic species in South Korea, nine bacterial species in the phylum Bacteroidetes were isolated from freshwater environmental samples that were collected from three major rivers in the Republic of Korea. High 16S rRNA gene sequence similarity (${\geq}98.7%$) and robust phylogenetic clades with the closely related species suggest that each strain was correctly assigned to an independent and predefined bacterial species. There were no previous reports of these nine species in Korea. Within the phylum Bacteroidetes, four species were assigned to the genus Flavobacterium, order Flavobacteriales, and five species to three genera of two families in the order Cytophagales. Gram reaction, colony and cell morphology, basic biochemical characteristics, isolation source, and strain IDs are described in the species description section.

• Biomedical Science Letters
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• v.22 no.4
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• pp.150-159
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• 2016

Knowledge of the distribution and biodiversity of environmental bacteria and the ecosystem that influences them is crucial for predicting an ecosystem. However, bacterial culture methods can only analyze approximately 0.1% of the existing microorganisms, those that are readily cultured under laboratory conditions. By contrast, next-generation sequencing (NGS) has generally been known to obtain more diverse profiling of bacterial composition. We compared the bacterial communities using both a culture-dependent (MALDI-TOF) and culture-independent (NGS) methods. Environmental specimens were obtained from both freshwater and seawater. Water samples were also analyzed by both pyrosequencing and MiSeq sequencing, in order to select one NGS platform which could analyze comparatively more diverse microbiota. Bacterial distribution analyzed with MALDI-TOF showed no difference between the microbiota of freshwater and seawater, whereas the results analyzed with NGS distinguished between the two. The diversity indexes of MiSeq sequencing were higher than for Pyrosequencing. This indicated that MiSeq sequencing is capable of analyzing a comparatively wider diversity of bacteria. The genus of Flavobacterium and Planktophila were identified as being unique to freshwater, whereas EU801223 and OM43 were found in the seawater. Difference between the bacterial composition of the freshwater and seawater environments was identified by MiSeq sequencing analysis.

• Mycobiology
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• v.50 no.5
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• pp.326-344
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• 2022

The fungal-like family Saprolegniaceae (Oomycota), also called "water mold," includes mostly aquatic saprophytes as well as notorious aquatic animal pathogens. Most studies on Saprolegniaceae have been biased toward pathogenic species that are important to aquaculture rather than saprotrophic species, despite the latter's crucial roles in carbon cycling of freshwater ecosystems. Few attempts have been made to study the diversity and ecology of Saprolegniaceae; thus, their ecological role is not well-known. During a survey of oomycetes between 2016 and 2021, we investigated the diversity and distribution of culturable Saprolegniaceae species in freshwater ecosystems of Korea. In the present study, members of Saprolegniaceae were isolated and identified at species level based on their cultural, morphological, and molecular phylogenetic analyses. Furthermore, substrate preference and seasonal dynamics for each were examined. Most of the species were previously reported as animal pathogens; however, in the present study, they were often isolated from other freshwater substrates, such as plant debris, algae, water, and soil sediment. The relative abundance of Saprolegniaceae was higher in the cold to cool season than that in the warm to hot season of Korea. This study enhances our understanding of the diversity and ecological attributes of Saprolegniaceae in freshwater ecosystems.

• Journal of Species Research
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• v.5 no.3
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• pp.539-540
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• 2016

Microturbellarians, small free-living Platyhelminthes are rich in freshwater environments. They are useful as indicator of water quality. There has never been a record of microturbellarians in Korea. Here I report a microturbellarian species, Catenula confusa Nuttycombe, 1956. Although specimens in this study show some differences with those of the original description of C. confusa in length and width of zooid, they conform to the specific diagnosis of this species.

• Journal of environmental and Sanitary engineering
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• v.11 no.3
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• pp.9-12
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• 1996

Polychlorinated biphenyl (PCBs) is one of major toxic pollutants in marine environments, This artificial chlorinated compound has been found in freshwater, seawater, soil, sediments and organismes living in various environments. Because of its toxicity and degradability, its uses in industrial processes have been banned after 1984 in Korea. Coastal area is an important environment for agriculture, industry, transportation, reduction of pollution loads through biogeochemical processes, cycling of nutrients and recreation. Input of pollutants from land and freshwater has been occurring through runoff, rivers and estuaries. Concentrations of PCBs were determined with GC-ECD. Concentrations of PCBs were in the range of 1.0 - 19.2 ng/g-dry weight of sediment(g-d.w.) at Ulsan, 4.5 -8,2 ng/g-d.w. at Onsan, 2.7 - 33.5 ng/g-d.w. at Masan and 4.0 - 60.7 ng/g-d.w. in Kwangyang, In Inchon area, PCBs were not detected in sediments. In sediments of Nakdong estuary, the distribution of PCBs' concentrations was 0.19 - 303 ng/g-d.w.

• The Korean Journal of Mycology
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• v.48 no.2
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• pp.103-116
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• 2020

Freshwater ecosystems provide a complex environment for microorganisms. In this study, we isolated diverse fungal strains from plant litter in freshwaters. These strains were identified using molecular phylogenetic analyses of rDNA and/or other gene sequences (TUB, GAPDH, and EF1). In addition, we examined their morphological characteristics by microscopy and cultural characteristics on several media. We identified six previously unrecorded Sordariomycetes species in Korea, i.e., Colletotrichum godetiae, Discosia rubi, Robillarda sessilis, Monochaetia dimorphospora, Idriella lunata, and Phialemoniopsis endophytica. Of these, D. rubi and M. dimorphospora exhibited high extracellular amylase, lipase, and protease activities, suggesting that these fungal isolates might play an important role as decomposers in freshwater ecosystems. Plant litter could thus be a good source for isolating and investigating previously undocumented fungal species in freshwater environments.

• Mycobiology
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• v.47 no.2
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• pp.135-142
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• 2019

Many members of the Saprolegniales (Oomycete) cause mycoses and disorders of fishes, of which Achlya and Saprolegnia are most ubiquitous genera worldwide. During a survey of the diversity of freshwater oomycetes in Korea, we collected seven isolates of Achlya, for which morphological and molecular phylogenetic analyses enabled them to identify as Achlya americana and Achlya bisexualis. In Korea, only a species of Achlya, A. prolifera, has been previously found to cause seedling rot on rice (Oryza sativa), but none of the two species have been reported yet. Importantly, A. bisexualis was isolated from a live fish, namely rice fish (Oryzias sinensis), as well as freshwater, and this is the first report of Achlya-causing mycoses on freshwater fishes in Korea. The presence of A. americana and A. bisexualis on live fish in Korea should be closely monitored, as considering the well-known broad infectivity of these species it has the potential to cause an important emerging disease on aquaculture industry.

• The Korean Journal of Mycology
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• v.46 no.1
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• pp.1-8
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• 2018

Three fungal isolates, NNIBRFG108, 1139, and 1480, were isolated from freshwater environments; NNIBRFG108 from plant litter in Samcheok, Gangwon and NNIBRFG1139 and 1480 from the soil in Jeju & Gimcheon, Gyeongbuk, Korea. Based on the morphological characteristics and phylogenetic analysis of internal tanscribed spacer (ITS), 28S rDNA region, and ${\beta}$-tubulin gene, NNIBRFG108, NNIBRFG1139, and NNIBRFG1480 isolates were confirmed as Didymella segeticola, D. ellipsoidea, and D. aeria, respectively. Neither species has previously been described in Korea.

• Animal Systematics, Evolution and Diversity
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• v.33 no.1
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• pp.37-44
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• 2017

The present census on freshwater bryozoans in the Han River, Geum River and in lentic water bodies in Gangwon Province revealed three gymnolaemate species. Two of them-Hislopia prolixa Hirose and Mawatari, 2011 and Victorella pavida Saville Kent, 1870 were recorded for the first time from South Korea. Paludicella articulata (Ehrenberg, 1831), on the other hand, had already been documented from a few sites since 1941. The bryozoans, all belonging to the order of Ctenostomata, were found on a variety of substrates in freshwater (H. prolixa and P. articulata) and brackish habitats (V. pavida). Hislopia prolixa had recently been established as a new species and this is the first record for an occurrence outside of Japan, where it had been newly described from Lake Biwa and nearby satellite lakes.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2001.10a
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• pp.313-314
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• 2001

The palaemonid shrimp Exopazaemon modestus inhabits the freshwater of the Indo-West Pacific, Siberia, Manchuira, Korea, China, Taiwan (Holthuis, 1980) and is abundant in the fresh water areas of southwest of Korea. Palaemonid shrimps are adapted to a variety of habitats in freshwater, brackish and marine environments. They play important role in the ecosystem of fresh, brackish and marine waters, acting as predators feeding on algae, detritus, crustaceans and meiofauna (Bell and Coull, 1978) and in turn, as preys for fishes and other predators (Anderson, 1985). (omitted)