https://repository.kopri.re.kr/handle/201206/5534 2026-04-15T04:38:05Z https://repository.kopri.re.kr/handle/201206/6713 Title: Bacterial Communities of Surface Mixed Layer in the Pacific Sector of the Western Arctic Ocean during Sea-Ice Melting Authors: Lee, Yoo Kyung; Han, Dukki; Kang, Ilnam; Ha, Ho Kyung; Kim, Hyun-cheol; Kim, Ok-Sun; Lee, Bang Yong; Cho, Jang-Cheon; Hur, Hor-Gil Abstract: From July to August 2010, the IBRV ARAON journeyed to the Pacific sector of the Arctic Ocean to monitor bacterial variation in Arctic summer surface-waters, and temperature, salinity, fluorescence, and nutrient concentrations were determined during the ice-melting season. Among the measured physicochemical parameters, we observed a strong negative correlation between temperature and salinity, and consequently hypothesized that the melting ice decreased water salinity. The bacterial community compositions of 15 samples, includicng seawater, sea-ice, and melting pond water, were determined using a pyrosequencing approach and were categorized into three habitats: (1) surface seawater, (2) ice core, and (3) melting pond. Analysis of these samples indicated the presence of local bacterial communities;a deduction that was further corroborated by the discovery of seawater- and ice-specific bacterial phylotypes. In all samples, the Alphaproteobacteria, Flavobacteria, and Gammaproteobacteria taxa composed the majority of the bacterial communities. Among these, Alphaproteobacteria was the most abundant and present in all samples, and its variation differed among the habitats studied. Linear regression analysis suggested that changes in salinity could affect the relative proportion of Alphaproteobacteria in the surface water. In addition, the species-sorting model was applied to evaluate the population dynamics and environmental heterogeneity in the bacterial communities of surface mixed layer in the Arctic Ocean during sea-ice melting. 2014-01-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/8511 Title: Bacterial Community Shift in Depth Profiles of Permafrost Soil in Alaska Authors: Lee, Yoo Kyung; Nam, Sungjin; Kim, Ok-Sun; Lee, Bang Yong; Chun, Jongsik; Han, Duk Ki; Kim, Hye Min Abstract: Despite the potential contribution of thawing permafrost soil to the global climate change, the research of the microbial diversity has been scarce. In this study, we investigate the bacterial community in active layer soil from the Alaskan high Arctic based on 16S rRNA genes. These bacterial habitats contained relatively low number of OTUs ranged from 397 to 1728 compared to the temperate habitats. Although the bacterial diversity was relatively low, 20 known divisions and 27 unknown divisions were detected. The phyla of Proteobacteria (35.2%), Actinobacteria (20.9%) and Acidobacteria (16.5%) were predominant. Community shift was observed significantly along the soil depth profiles, which certain increase or decrease of relative abundance was detected in some phyla. The comparison between communities based on PCoA indicated that the bacterial composition was separated at 15 cm depth. This suggests that certain environmental parameters drive the formation of bacterial composition in this habitat. This study provides new insight regarding the bacterial communities in the Alaskan high Arctic permafrost. 2011-01-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/8514 Title: PROKARYOTIC MICROBIAL DIVERSITY OF ACTIVE LAYER SOIL FROM ALASKA PERMAFROST Authors: Kim, Ok-Sun; Lee, Bang Yong; Lee, Yoo Kyung; Nam, Sungjin; Kim, Hye Min; Chae, Nam Yi; Han, Duk Ki Abstract: Permafrost thaw results in the organic matter decomposition of previously frozen organic carbon, which is considered a positive feedback of carbon from terrestrial ecosystem to atmosphere. Despite the organic matter decomposition is closely related with microbial community structure, the research of the microbial diversity in permafrost has been limited. In this study, we investigated the microbial diversity in the active layer soil from Alaska permafrost based on 16S rRNA genes using pyrosequencing. The phyla of Proteobacteria, Acidobacteria and Actinobacteria were frequently detected in the active layer soil. Species richness and species evenness were compared along the soil depth. Soil CO2 concentration, air CO2 concentration, soil temperature and water content were measured, and relationship of these environmental factors and microbial diversity was analyzed. In conclusion, microbial diversity in this ecosystem can be readily monitored by pyrosequencing of 16S rRNA gene. 2011-01-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/8510 Title: What I did, am doing, and will do??? Authors: Kim, Ok-Sun Abstract: 한국-일본 젊은과학자 분야에서 박사학위 과정 후의 진로 결정 및 현재의 연구 분야에 대한 소 개 2011-01-01T00:00:00Z