https://repository.kopri.re.kr/handle/201206/5541 Wed, 11 Mar 2026 14:18:25 GMT 2026-03-11T14:18:25Z https://repository.kopri.re.kr/handle/201206/6398 Title: Niche specialization of bacteria in permanently ice-covered lakes of the McMurdo Dry Valleys, Antarctica Authors: Kwon, Miye; Kim, Ok-Sun; John C Priscu; Kim, Sang Jong; Hong, Soon Gyu; Lee, Jaejin; Cristina Takacs-Vesbach; Kim, Mincheol Abstract: Perennially ice-covered lakes in the McMurdo Dry Valleys are chemically stratified with depth and have distinct biological gradients. Despite the long-term studies on these unique environments there remains a paucity of data on microbial community structure in the water columns of these lakes. We investigated bacterial diversity in five different ice-covered Antarctic lakes using 16S rRNA gene-based pyrosequencing. Distinct communities were present in each lake, paralleling the unique biogeochemical characteristics of each environment. Certain bacterial lineages were confined exclusively to a specific depth of each lake. For example, Candidate division WM88 occurred at 15 m depth of Lake Fryxell solely, while unknown lineages of Chlorobi are found only at the depth of 18 m in Lake Miers. The 30 m depth of East and West Lobe Bonney was occupied by two distinct Firmicutes classes. Redundancy analysis revealed that community variation of bacterioplankton was explained by the different chemistries unique to each lake and depth. In particular, assemblages from deeper layers beneath the chemocline had distinct biogeochemical associations differing from those of the upper layers. These patterns of community composition may represent bacterial adaptations to the extreme and unique biogeochemical gradients of ice-covered lakes in the McMurdo Dry Valleys. Sun, 01 Jan 2017 00:00:00 GMT https://repository.kopri.re.kr/handle/201206/6398 2017-01-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/7474 Title: Influence of Soil Characteristics and Proximity to Antarctic Research Stations on Abundance of Antibiotic Resistance Genes in Soils Authors: Robert D. Stedtfeld; Hyoun Soo Lim; Fang Wang; Sul, Woo Jun; James M. Tiedje; Syed A. Hashsham; Kim, Dockyu; Hong, Soon Gyu; Tiffany M. Stedtfeld; Luxi Yang; Benli Chai; Kim, Ok-Sun Abstract: Soil is an important environmental reservoir of antibiotic resistance genes (ARGs), which are increasingly recognized as environmental contaminants. Methods to assess the risks associated with the acquisition or transfer of resistance mechanisms are still underdeveloped. Quantification of background levels of antibiotic resistance genes and what alters those is a first step in understanding our environmental resistome. Towards this goal, 62 samples were collected over 3 years from soils near the 30-year old Gondwana Research Station and for 4 years before and during development of the new Jang Bogo Research Station, both at Terra Nova Bay in Antarctica. These sites reflect limited and more extensive human impact, respectively. A qPCR array with 384 primer sets targeting antibiotic resistance genes and mobile genetic elements (MGEs) was used to detect and quantify these genes. A total of 73 ARGs and MGEs encompassing eight major antibiotic resistance gene categories were detected, but most at very low levels. Antarctic soil appeared to be a common reservoir for seven ARGs since they were present in most samples (42%-88%). If the seven widespread genes were removed there was a correlation between the relative abundance of MGEs and ARGs, more typical of contaminated sites. There was a relationship between ARG content and distance from both research stations, with a significant effect at the Jang Bogo Station especially when excluding the seven widespread genes, however the relative abundance of ARGs did not increase over the 4 year period. Silt, clay, total organic carbon and SiO2 were the top edaphic factors that correlated with ARG abundance. Overall, this study identifies that human activity and certain soil characteristics correlate with antibiotic resistance genes in these oligotrophic Antarctic soils and provides as a baseline on ARGs and MGEs for future comparisons. Fri, 01 Jan 2016 00:00:00 GMT https://repository.kopri.re.kr/handle/201206/7474 2016-01-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/7303 Title: Highly heterogeneous soil bacterial communities around Terra Nova Bay of Northern Victoria Land, Antarctica Authors: Kim, Mincheol; Kim, Ok-Sun; Ahn, Tae Seok; Choi, Taejin; Lee, Joohan; Kim, Ji Hee; Hong, Soon Gyu; Lim, Hyoun Soo; Cho, Ahnna Abstract: Given the diminished role of biotic interactions in soils of the continental Antarctica, abiotic factors have been believed to be the most prevailing parameter in structuring microbial communities. Many ice-free regions still remain unexplored and little is understood about which environmental gradients dominate the variation of bacterial communities. In this study, we investigated the soil bacterial community around Terra Nova Bay of Victoria Land using pyrosequencing and determined which environmental variables govern the bacterial community structure at the local scale. Six bacterial phyla such as Actinobacteria, Proteobacteria, Acidobacteria, Chloroflexi, Cyanobacteria, and Bacteroidetes were dominant but their relative abundance greatly varied across locations. Bacterial community structures were little affected by spatial distance but structured more strongly by site difference which parallels to the variation of soil physicochemical compositions. At both phylum- and species levels, bacterial community structure was explained most by pH and water content and to a lesser extent certain earth elements and trace metals also had important roles in shaping community variation. The higher level of heterogeneity of bacterial community structure found in this local site indicates how soil bacterial communities have been distinctively adapted to different compositions of edaphic variables under extreme environmental conditions. Taken together, these findings will greatly advance our understanding about how soil bacterial populations have been adapted to this harsh environment and how they will respond to changing climates in the future. Thu, 01 Jan 2015 00:00:00 GMT https://repository.kopri.re.kr/handle/201206/7303 2015-01-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/8359 Title: Comparative analysis of bacterial taxonomic and functional diversity in terrestrial environments of Barton Peninsula in King George Island Authors: Oh, Jung Soo; Lim, Hyounsoo; Hong, Soon Gyu; Noh, Hyun-Ju; Cho, Ahnna; Kim, Ok-Sun Abstract: Recent applications of molecular methods to study of microbial ecology have allowed the extension of our knowledge that terrestrial environments in Antarctica contain unexpected high diversity of microorganisms. In the present study, we conducted a comparative analysis of bacterial communities in soil samples from Barton Peninsular in King George Island, the maritime Antarctic. Total 43 samples with different soil types near King Sejong Station were collected in December, 2010. On the basis of the 16S rRNA genes using pyrosequencing, 5,924 OTUs from total 85,078 bacterial sequences were detected using 97% similarity cutoff. Twenty known divisions and 20 unknown divisions were recognized, where the phyla of Proteobacteria (20.7%), Actinobacteria (18.6%) and AD3 (13.4%) were dominant. Interestingly, unexpected diverse phylotypes of AD3 with 99 OTUs were detected, which found only from environments. The bacterial taxonomic and functional diversity was deeply affected by various physicochemical conditions. These findings imply new perspectives of the relationship between microbial ecology and environmental characters in this unique ecosystem. conducted a comparative analysis of bacterial communities in soil samples from Barton Peninsular in King George Island, the maritime Antarctic. Total 43 samples with different soil types near King Sejong Station were collected in December, 2010. On the basis of the 16S rRNA genes using pyrosequencing, 5,924 OTUs from total 85,078 bacterial sequences were detected using 97% similarity cutoff. Twenty known divisions and 20 unknown divisions were recognized, where the phyla of Proteobacteria (20.7%), Actinobacteria (18.6%) and AD3 (13.4%) were dominant. Interestingly, unexpected diverse phylotypes of AD3 with 99 OTUs were detected, which found only from environments. The bacterial taxonomic and functional diversity was deeply affected by various physicochemical conditions. These findings imply new Sun, 01 Jan 2012 00:00:00 GMT https://repository.kopri.re.kr/handle/201206/8359 2012-01-01T00:00:00Z