The long term focus of our research is to examine the diversity and survival of microorganisms in cold environments and weave together information about their identity, habitats, and metabolism.
Recently we developed a comprehensive picture of the microbial diversity in ice core samples from the 3 km deep Greenland ice sheet where microbial life and past climates have been preserved chronologically. We recovered a large collection of ultrasmall bacterial isolates that had remained viable for over 100,000 years at temperatures as low as minus 35°C and described novel bacterial species Herminiimonas glaciei and Chryseobacterium greenlandense.
We explored the possibility that the historically prevalent climate conditions may have altered the microbial abundance and composition resulting in different diversity patterns. Because these results are important for determining whether in situ microbial metabolism could influence trace gases trapped in ice cores used to determine past climate records, we expanded these studies to include long term monitoring and detecting microbial activity of ice core samples and model organisms at sub-zero temperatures down to -32oC.
A new focus of our research is determining the extent and sources of contamination with exogenous microbes during ice core drilling that may compromise the authenticity of the indigenous microbial populations. We used the recent Greenland North Eemian (NEEM) drilling project as a first-time opportunity to assess potential microbial contamination throughout the drilling process by: a) microbiological and molecular analyses of the drilling fluid; b) tracking the penetration of the drilling fluid along the grain boundaries, and c) deployment of fluorescent microspheres as surrogates of potential microbial contaminants in the borehole at different depths representing major ice structures (bubbly, brittle and clathrated ice).
Our research will create a more comprehensive picture of the microbial populations within the largest ice sheet in the Northern hemisphere and help answer important questions about the limits of microbial life, mechanisms of survival, and metabolism within glacial ice. The development of strategies to detect contamination of ice cores during the drilling process will be valuable to both future microbiologists and others searching for extraterrestrial life and biosignatures.