https://repository.kopri.re.kr/handle/201206/5357 2026-04-04T07:58:12Z https://repository.kopri.re.kr/handle/201206/7364 Title: Bacterial communities along stratified water columns at the Chukchi Borderland in the western Arctic Ocean Authors: Han, Dukki; Lee, Yoo Kyung; Hur, Hor-Gil; Lee, Bang Yong; Hwang, Chung Yeon; Ha, Ho Kyung Abstract: An expedition of the IBRV ARAON took place in the Arctic Ocean during the summer of 2010. To investigate the hydrographic features and bacterial variations in water columns, we categorized 16 water samples collected from distinct water masses in the Arctic Ocean. Bacterial diversity, relative abundance, and community composition were determined based on a pyrosequencing approach, and their relationship with water mass properties was considered. Alphaproteobacteria (43.2%), Gammaproteobacteria (16.7%), Flavobacteria (13.7%), and Deltaproteobacteria (12.0%) were the most common bacteria found in all samples, and the relative abundance of these predominant genera represent the population dynamics of bacterial communities in different water masses (from the euphotic to the sub-euphotic zone) in the Arctic Ocean. Furthermore, the relative abundance of Alphaproteobacteria and its subgroup, SAR11 group I, were significantly related to depth change in water columns, suggesting that environmental heterogeneity caused by changes in depth may play an important role in bacterial population dynamics. In this study, bacterial communities in the Arctic Ocean exhibit biogeographic patterns according to the type of water mass. The halocline layer between the Pacific winter water and Atlantic water exhibits a variation in the composition of bacterial communities, which may be influenced by mixing of Pacific winter water and Atlantic water. 2015-01-01T00:00:00Z 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/201206/5612 Title: Isolation of facultatively anaerobic soil bacteria from Ny-A° lesund, Svalbard Authors: Jung, Ji Young; Chae, Nam Yi; Kim, Hye Min; Lee, Yoo Kyung Abstract: Anaerobic conditions in soil commonly occur even in upland environments. Physiological and biogeochemical properties of individual anaerobic bacteria, however, have been poorly understood due to difficulties in culture. This study aimed to isolate anaerobic bacteria in the Arctic tundra soil and to identify their physiological characteristics. Anaerobic culture and 16S rRNA gene sequence-based phylogenetic analysis showed that total 33 bacterial strains were affiliated with 15 species from the following 8 genera: Bacillus, Carnobacterium, Clostridium, Paenibacillus, and Trichococcus (Firmicutes), Pseudomonas and Rahnella (Gamma-proteobacteria) and Cellulomonas (Actinobacteria). All isolates were identified as facultatively anaerobic bacteria this finding might be partially attributed to the characteristics of sampling sites, which temporarily developed anaerobic conditions because of the presence of stagnant melting snow. Six of the 33 bacterial strains were revived subsequently from glycerol stocks held -80 °C, and these were used for the physiological study: four isolates from Firmicutes, one isolate from Gamma-proteobacteria and one isolate from Actinobacteria. Five isolates except KOPRI 80146 (Bacillus sp.) could grow at either 4 °C or 10 °C within a week. All six isolates showed cellulase or protease activities at 10 °C or 15 °C. Endospores were observed from four isolates belonging to Firmicutes. These physiological characteristics may contribute to the survival of these organisms at low temperatures and to their involvement in biogeochemical cycles in the tundra soil. These isolates may be used for further detailed studies for identifying their cold-adaptation mechanisms and ecological roles in the Arctic. 2013-01-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/5611 Title: Inclined Lidar observations of boundary layer aerosol particles above the Kongsfjord, Svalbard Authors: ritter C.; Strom J.; Lampert A.; Chae, Nam Yi; Yoon, Young Jun; Neuber R.; Shiobara M. Abstract: A lidar system was used as a link between the observatory at the ridge of Zeppelin Mountain (475 m asl) and the observatories at sea level in Ny-？lesund, Svalbard. We report on the observation of aerosol layers directly above the Kongsfjord for two particular days, 29 April and 1 May 2007. On 29 April 2007, a layer of enhanced backscatter was observed in the lowest 25 m above the water surface from 10:00 until 13:00 UTC. The depolarization was low, indicating spherical particles like hydrated aerosol or water droplets. In the afternoon, this layer disappeared. The particle concentration at Zeppelin station was low all day (around 250 cm-3 for particles with diameter bigger than 10 nm, around 300 cm-3 for particles larger than 3 nm). At Corbel station (sea level, near the Kongsfjord), a similar concentration of particles larger than 2.5 nm was monitored.Kongsfjord for two particular days, 29 April and 1 May 2007. On 29 April 2007, a layer of enhanced backscatter was observed in the lowest 25 m above the water surface from 10:00 until 13:00 UTC. The depolarization was low, indicating spherical particles like hydrated aerosol or water droplets. In the afternoon, this layer disappeared. The particle concentration at Zeppelin station was low all day (around 250 cm-3 for particles with diameter bigger than 10 nm, around 300 cm-3 for particles larger than 3 nm). At Corbel station (sea level, near the Kongsfjord), a similar concentration of particles larger than 2.5 nm was monitored. 2012-01-01T00:00:00Z