An international team of scientists has reported the discovery of previously unknown microbial communities living beneath the Antarctic ice sheet in Mercer Subglacial Lake. The research, which involved drilling more than 1,000 meters into the ice to reach the lake, was part of the Subglacial Antarctic Lake Scientific Access (SALSA) project and included collaboration between Korean and U.S. researchers.
Mercer Subglacial Lake is located under 1,085 meters of ice in West Antarctica and has been cut off from surface conditions for thousands of years. To avoid contamination, researchers used a clean hot-water drilling system to collect water and sediment samples. Genetic analysis identified 1,374 single-cell amplified genomes (SAGs), most of which belong to species not previously documented in marine or surface environments.
The study found that microbial communities in the lake have developed various survival strategies based on oxygen levels. These include both heterotrophy—using organic matter—and chemoautotrophy—gaining energy from inorganic compounds.
“Microbes in the subglacial lake have evolved to survive without sunlight, in total darkness, and with extremely limited energy sources,” said co-first author Dr. Kyuin Hwang of KOPRI. “They display a range of metabolic strategies — oxidizing either organic matter or inorganic compounds depending on oxygen availability — and this metabolic flexibility is likely the key to their survival.”
The SALSA project was supported by KOPRI’s institutional program and funding from the U.S. National Science Foundation (NSF). The team included Prof. John Priscu (Montana State University / Desert Research Institute, Chief Scientist), Prof. Brent Christner (University of Florida), Dr. Ok-Sun Kim (KOPRI, Co-PI), and Christina L. Davis (University of Florida; research scientist).
This expedition marks only the second successful effort to access an Antarctic subglacial lake without contamination; Whillans Subglacial Lake was accessed similarly in 2013 by a U.S.-led team.
The findings may also have implications for astrobiology by informing searches for life on icy moons such as Europa and Enceladus, which are believed to have subsurface oceans beneath their icy surfaces.
“This is the world’s first successful single-cell genomic analysis from a subglacial lake, revealing microbial adaptation and evolution in darkness, low-nutrient, and high-pressure environments,” said President Hyung Chul Shin of KOPRI. “Of more than 600 known Antarctic subglacial lakes, only two have yielded samples, making this a landmark achievement in polar science. We will continue to lead global efforts to explore and understand Earth’s least-known ecosystems.”