https://repository.kopri.re.kr/handle/201206/9764 Fri, 17 Apr 2026 14:10:18 GMT 2026-04-17T14:10:18Z https://repository.kopri.re.kr/handle/201206/16130 Title: Genetic isolation and metabolic complexity of an Antarctic subglacial microbiome Authors: Hwang, Kyuin; Kim, Kyung Mo; Lee, Hanbyul; Cho, Ahnna; Davis Christina L.; Christner Brent C.; Priscu John C.; Kim, Ok-Sun Abstract: Microbes inhabiting and evolving in aquatic ecosystems beneath polar ice sheets subsist under energy-limited conditions while in relative isolation from surface gene pools and their common ancestral populations of origin. Samples obtained from beneath West Antarctic Ice Sheet (WAIS) allowed us to examine evolutionary relationships of and identify metabolic pathways in microbial genomes recovered from the Mercer Subglacial Lake (SLM) ecosystem. We obtained 1,374 single-cell amplified genomes (SAGs) from individual bacterial and archaeal cells that were isolated from samples of SLM's water column and sediments. These genomes reveal that a diversity of microorganisms including Patescibacteria exists in SLM. Comparative analyses show that most genomes correspond to new species and taxonomic groups, with phylogenomic and functional evidence supporting their genetic isolation from marine and surface biomes. Genomic data reveal diverse metabolisms in SLM that are capable of oxidizing organic and inorganic compounds via aerobic or anaerobic respiration. Distinct metabolic guild structures are observed for the subglacial populations, where trophic shifts from organotrophy to chemolithotrophy may depend on oxygen availability. Our SAG data suggest versatile metabolic capabilities in the characterized microbial assemblage, reveal key energy-generating strategies in the subglacial aquatic ecosystem, and provide a framework to assess microbial evolution beneath WAIS. Fri, 01 Aug 2025 00:00:00 GMT https://repository.kopri.re.kr/handle/201206/16130 2025-08-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/16223 Title: Microbial assemblages and associated biogeochemical processes in Lake Bonney, a permanently ice-covered lake in the McMurdo Dry Valleys, Antarctica Authors: Lee, Hanbyul; Hwang, Kyuin; Cho, Ahnna; Kim, Soyeon; Kim, Minkyung; Morgan-Kiss Rachael; Priscu John C.; Kim, Kyung Mo; Kim, Ok-Sun Abstract: BackgroundLake Bonney, which is divided into a west lobe (WLB) and an east lobe (ELB), is a perennially ice-covered lake located in the McMurdo Dry Valleys of Antarctica. Despite previous reports on the microbial community dynamics of ice-covered lakes in this region, there is a paucity of information on the relationship between microbial genomic diversity and associated nutrient cycling. Here, we applied gene- and genome-centric approaches to investigate the microbial ecology and reconstruct microbial metabolic potential along the depth gradient in Lake Bonney.ResultsLake Bonney is strongly chemically stratified with three distinct redox zones, yielding different microbial niches. Our genome enabled approach revealed that in the sunlit and relatively freshwater epilimnion, oxygenic photosynthetic production by the cyanobacterium Pseudanabaena and a diversity of protists and microalgae may provide new organic carbon to the environment. CO-oxidizing bacteria, such as Acidimicrobiales, Nanopelagicales, and Burkholderiaceae were also prominent in the epilimnion and their ability to oxidize carbon monoxide to carbon dioxide may serve as a supplementary energy conservation strategy. In the more saline metalimnion of ELB, an accumulation of inorganic nitrogen and phosphorus supports photosynthesis despite relatively low light levels. Conversely, in WLB the release of organic rich subglacial discharge from Taylor Glacier into WLB would be implicated in the possible high abundance of heterotrophs supported by increased potential for glycolysis, beta-oxidation, and glycoside hydrolase and may contribute to the growth of iron reducers in the dark and extremely saline hypolimnion of WLB. The suboxic and subzero temperature zones beneath the metalimnia in both lobes supported microorganisms capable of utilizing reduced nitrogens and sulfurs as electron donors. Heterotrophs, including nitrate reducing sulfur oxidizing bacteria, such as Acidimicrobiales (MAG72) and Salinisphaeraceae (MAG109), and denitrifying bacteria, such as Gracilimonas (MAG7), Acidimicrobiales (MAG72) and Salinisphaeraceae (MAG109), dominated the hypolimnion of WLB, whereas the environmental harshness of the hypolimnion of ELB was supported by the relatively low in metabolic potential, as well as the abundance of halophile Halomonas and endospore-forming Virgibacillus.ConclusionsThe vertical distribution of microbially driven C, N and S cycling genes/pathways in Lake Bonney reveals the importance of geochemical gradients to microbial diversity and biogeochemical cycles with the vertical water column. Mon, 01 Jan 2024 00:00:00 GMT https://repository.kopri.re.kr/handle/201206/16223 2024-01-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/12097 Title: Methane production in the oxygenated water column of a perennially ice-covered Antarctic lake Authors: Li, Wei; Dore, John E.; Steigmeyer, August J.; Cho, Yong-Joon; Kim, Ok-Sun; Liu, Yongqin; Morgan-Kiss, Rachael M.; Skidmore, Mark L.; Priscu, John C. Abstract: Aerobic methane production in aquatic ecosystems impacts the global atmospheric budget of methane, but the extent, mechanism, and taxa responsible for producing this greenhouse gas remain unclear. Lake Bonney (LB), a perennially ice-covered Antarctic lake, has cold hypersaline waters underlying an oxygenated freshwater layer. We present temporal methane concentration profiles in LB indicating methane production in the oxygenated (>200% air saturation) water. Experiments amended with methylphosphonate (MPn) yielded methane generation, suggesting in situ methanogenesis via the carbonphosphorus (C-P) lyase pathway. Enrichment cultures from the lake were used to isolate five bacterial strains capable of generating methane when supplied with MPn as the sole P source. Based on 16S rRNA gene sequencing, the isolates belong to the Proteobacteria (closely related to Marinomonas, Hoeflea and Marinobacter genera) and Bacteroidetes (Algoriphagus genus). 16S rRNA metagenomic sequencing confirms the presence of these taxa in LB. None of the isolated species were reported to be capable to produce methane. In addition, orthologs of the phosphoenolpyruvate mutase gene (PepM) and methylphosphonate synthase (MPnS), enzymes involved in phosphonate and methylphosphonate biosynthesis, were widely spread in the LB shotgun metagenomic libraries; genes related to C-P lyase pathways (phn gene clusters) were also abundant. Anaerobic methanogenic 16S rRNA and mcrA genes were absent in both 16S rRNA and metagenomics libraries. These data reveal that in situ aerobic biological methane production is likely a significant source of methane in LB. Wed, 01 Jan 2020 00:00:00 GMT https://repository.kopri.re.kr/handle/201206/12097 2020-01-01T00:00:00Z