Microbial assemblages and associated biogeochemical processes in Lake Bonney, a permanently ice-covered lake in the McMurdo Dry Valleys, Antarctica

• Published in: Environmental Microbiome
• Main Authors: Hanbyul Lee, Kyuin Hwang, Ahnna Cho, Soyeon Kim, Minkyung Kim, Rachael Morgan-Kiss, John C. Priscu, Kyung Mo Kim, Ok-Sun Kim
• Format: Article in Journal/Newspaper
• Language: English
• Published: BMC 2024
• Subjects: Hypersaline; Cryosphere; Metagenomics; Biogeochemical cycles; Microbial metabolism; Environmental sciences; GE1-350; Microbiology; QR1-502; Bonney; Lake Bonney; McMurdo Dry Valleys; Taylor Glacier; Antarc*; Antarctica
• Online Access: https://doi.org/10.1186/s40793-024-00605-1; https://doaj.org/article/5b6d66b27cd8431691ce0b1d31b00092

Abstract Background Lake 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. Results Lake 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 ...