Microbial Community Profiling and Metagenome Analysis in Ice-covered Lake Fryxell of the McMurdo Dry Valleys, Antarctica

Abstract

Perennially ice-covered lake Fryxell in McMurdo dry valleys is chemically stratified and characterized by its own distinct limnology and biogeochemistry. The bottom of the lake is brackish, anoxic, and high concentrations of sulfide and methane. Despite the long history of microbiological research in these extreme environments, detailed information about what microbes reside and what they have potential function are still little understood. This study investigated bacterial community composition and their metabolic possibility in the bottom depth of lake Fryxell using 16S rRNA gene-based pyrosequencing and Illumina Miseq platform, respectively. Bacterial communities are overall distinctive.For example, all candidate phyla constitute more than half of total bacteria in this bottom depth including WM88, JS1, OD1, SAR406 and WS5, etc. Also, the high quality of 120 million reads were recovered from the sample with metagenome data, and 16S rRNA gene sequences was extracted about four thousands reads. The ratio of each bacterial community in pyrosequencing was differently shown from metagenome data. The metagenome data showed several metabolic pathways, including nitrogen and sulfur metabolism. Strong associations of bacterial community with various physicochemical variables would give additional information about ecology and metabolic potential of these bacteria, which would be consequences of their long-lasting adaptations to the extreme and unique environments of lake Fryxell in Antarctica.