https://repository.kopri.re.kr/handle/201206/5361 2026-04-17T15:15:22Z https://repository.kopri.re.kr/handle/201206/6358 Title: Variations in bacterial and archaeal communities along depth profiles of Alaskan soil cores Authors: Binu, M.; Lee, Yoo Kyung; Ahn, Jinho; Yang, Ji-Woong; Byun, Eunji; Kim, Yongwon; Kim, Mincheol Abstract: Understating the microbial communities and ecological processes that influence their structure in permafrost soils is crucial for predicting the consequences of climate change. In this study we investigated the bacterial and archaeal communities along depth profiles of four soil cores collected across Alaska. The bacterial and archaeal diversity (amplicon sequencing) overall decreased along the soil depth but the depth-wise pattern of their abundances (qPCR) varied by sites. The community structure of bacteria and archaea displayed site-specific pattern, with a greater role of soil geochemical characteristics rather than soil depth. In particular, we found significant positive correlations between methane trapped in cores and relative abundance of methanogenic archaeal genera, indicating a strong association between microbial activity and methane production in subsurface soils. We observed that bacterial phylogenetic community assembly tended to be more clustered in surface soils than in deeper soils. Analyses of phylogenetic community turnover among depth profiles across cores indicated that the relative influence of deterministic and stochastic processes was mainly determined by soil properties rather than depth. Overall, our findings emphasize that the vertical distributions of bacterial and archaeal communities in permafrost soils are to a large extent determined by the variation in sitespecific soil properties. 2018-01-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/8278 Title: Snow depth manipulation experiments in dry and moist tundra Authors: 권민정; Ioan Wagner; Nam, Sungjin; Lee, Yoo Kyung; Kim, Mincheol; Jung, Ji Young; Claudia I. Czimczik Abstract: As a result of global warming, precipitation in the Arctic is expected to increase by 25-50% by the end of this century, mostly in the form of snow. However, precipitation patterns vary considerable in space and time, and future precipitation patterns are highly uncertain at local and regional scales. The amount of snowfall (or snow depth) influences a number of ecosystem properties in Arctic ecosystems, such as soil temperature over winter and soil moisture in the following growing season. These modifications then affect rates of carbon-related soil processes and photosynthesis, thus CO2 exchange rates between terrestrial ecosystems and the atmosphere. In this study, we investigate the effects of snow depth on the magnitude, sources and temporal dynamics of CO2 fluxes. We installed snow fences in a dry dwarf-shrub (Cambridge Bay, Canada; 69° N, 105° W) and a moist low-shrub (Council, Alaska, USA; 64° N, 165° W) tundra in summer 2017, and established control, and increased and reduced snow depth plots at each snow fence. Summertime CO2 flux rates (net ecosystem exchange, ecosystem respiration, gross primary production) and the fractions of autotrophic and heterotrophic respiration to ecosystem respiration were measured using manual chambers and radiocarbon signatures. Wintertime CO2 flux rates will be measured using soda lime adsorption technique and forced diffusion chambers. Soil temperature and moisture at multiple depths, as well as changes in soil properties and microbial communities will be also observed, to research whether these changes affect CO2 flux rates or patterns. Our study will elucidate how future snow depth and its impact on soil physical and biogeochemical properties influence the magnitude and sources of tundra-atmosphere CO2 exchange in the rapidly warming Arctic. 2017-01-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/5860 Title: Crystal Structure and Functional Characterization of an Esterase (EaEST) from Exiguobacterium antarcticum Authors: Lee, Chang Woo; Lee, Jun Hyuck; T. Doohun Kim; Park, Hyun; Sunghwan Kim; Shin, Seung Chul; Kim, Han-Woo; Bum Han Ryu; Wanki Yoo; Boo-Young Kim; Park, Sun-Ha; Sena Kwon Abstract: A novel microbial esterase, EaEST, from a psychrophilic bacterium Exiguobacterium antarcticum B7, was identified and characterized. To our knowledge, this is the first report describing structural analysis and biochemical characterization of an esterase isolated from the genus Exiguobacterium. Crystal structure of EaEST, determined at a resolution of 1.9 A, showed that the enzyme has a canonical α/β hydrolase fold with an α-helical cap domain and a catalytic triad consisting of Ser96, Asp220, and His248. Interestingly, the active site of the structure of EaEST is occupied by a peracetate molecule, which is the product of perhydrolysis of acetate. This result suggests that EaEST may have perhydrolase activity. The activity assay showed that EaEST has significant perhydrolase and esterase activity with respect to short-chain p-nitrophenyl esters (≤C8), naphthyl derivatives, phenyl acetate, and glyceryl tributyrate. However, the S96A single mutant had low esterase and perhydrolase activity. Moreover, the L27A mutant showed low levels of protein expression and solubility as well as preference for different substrates. On conducting an enantioselectivity analysis using R- and S-methyl-3-hydroxy-2-methylpropionate, a preference for R-enantiomers was observed. Surprisingly, immobilized EaEST was found to not only retain 200% of its initial activity after incubation for 1 h at 80°C, but also retained more than 60% of its initial activity after 20 cycles of reutilization. This research will serve as basis for future engineering of this esterase for biotechnological and industrial applications. 2017-01-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/8248 Title: Arctic Monitoring of KOREA Authors: Lee, Yoo Kyung Abstract: Since 2010, Korean scientists have performed the monitoring in various regions of the Arctic. As a member of the international community and good partner of the Arctic states, Korea has contributed the Arctic research to understand the impact of climate change on the Arctic environment. Korea Polar Research Institute (KOPRI), the leading organization of Arctic research, has an Ice Breaking Research Vessel, Araon. Using Araon, we have conducted multidisciplinary research in the Arctic Ocean. Since 2010, we have the Arctic expedition every year. Sea ice-covered area in the Pacific Central Arctic Ocean (CAO) is a major study site of the Korean Arctic program, regularly visited by its flagship and an icebreaker, Araon. We did Ocean-Sea Ice-Atmosphere Integrated Observations from 6-25 August 2017 in Northern Bering Sea to Southern Chukchi Sea, Chukchi shelf, and Chukchi Borderland to the East Siberian Sea. The aims of the cruise are to identify key environmental parameters in rapid transition due to the sea-ice decrease in the Pacific Central Arctic Ocean (CAO), to predict change patterns, and to understand sea ice dynamics and sea ice ecosystem. The chief scientist of this program is Dr. Sung-Ho Kang (shkang@kopri.re.kr), and 52 Scientists from 11 Countries (Korea, USA, Japan, China, France, Spain, UK, Germany, Italy, Croatia, Russia) have joined this cruise. KOPRI have provided a platform for international cooperation, welcoming numerous foreign scientists on board, providing instrument deployment opportunities and accommodating the ongoing and planned research initiatives. The second Arctic cruise is Arctic MArine Geoscience Expedition (AMAGE). To monitor methane releasing from the Arctic selves due to global warming, we have visited the Beaufort Sea during 27 August and 16 September 2017. This program has three main research questions: Is Arctic subsea permafrost/gas hydrate currently thawing? Is massive methane release really occurring from the Arctic Shelves? Can methane release in the Arctic Shelves cause the rapid global warming? We have also monitored environmental changes in Circum-Arctic Permafrost including Ny-Alesund in Svalbard, Council in Alaska, Cambridge Bay in Canada, Storhofdi observatory in Iceland, and Station Nord in Greenland. We have focused on green house gas that emitted from permafrost. We have operated greenhouse gas flux system and LED sensor to detect the color change of plants. We measured the net CO2 exchange, photosynthesis, and soil respiration. We have continued climate manipulation experiment more than 5 years. We have also monitored Dimethyl sulfide (DMS). In Russia, we started the monitoring of Greenhouse gas (and energy) fluxes exchanged between the atmosphere and permafrost in the Ice Base Cape Baranova in collaboration with AARI (Arctic & Antarctic Research Institute of Russia). In Svalbard, using Helmer Hanssen, we did Fjord cruise to understand paleo-environmental changes and glacial history. We are going to reconstruct paleo-environmental changes of Svalbard fjords since the last glacial maximum. We have also studied the chemical fate of Arctic pollutants trapped in various ice media and monitoring of new contaminants All the data are deposited at Korea Polar Data Centre belonged to Antarctic Master Directory managed by NASA. We share up to date information on the Arctic to stakeholders, researchers and anyone who is interested in Arctic through a website, Arctic Knowledge Center. As an observer state of the Arctic Council, we will sincerely continue to carry out the Arctic environmental monitoring with Arctic states. 2017-01-01T00:00:00Z