Biosignatures in ICY EnVIRONMENTS
Ice structure differs when formed in the presence of organics. Brine ice (A) is coarser than brine + exopolmeric substances (EPS) ammended ice (B) Contrast imaging shows brine vein networks sizes and connectivity are modified by the addition of EPS (C, D). Image from: Krembs et al. (2011).
Patterned microbial growths (dark grey curvilinear structures) are called biovermiculations. They are considered biosignatures of extant life.
Here we demonstrate their formation in response to nutrient limitation in the laboratory.
MicroHabitable environments in ice
When Malaska et al (2020) looked at ice cores in Greenland, they observed patchy distributions of life and organics in ice. In sea ice on Earth, organics, including carbohydrates, influence the formation of brine channels in ice, which provide habitats for microorganisms within ice (Krembs et al., 2011).
This new project seeks to understand how organics influence the formation and maintenance of these microhabitable environments in ice under Enceladus and Europa-like conditions. At the end of the project, we will have quantified the potential habitable volume of ice in Ocean Worlds ice shells.
Stay tuned for updates on our research progress.
nutrient availability drives snow algae growth and biosignature formation
Snow algae and bacterial communities occur in icy environments on Earth. It has been suggested that they weather minerals to overcome nutrient limitation. My work examines these processes and how their dissolution of primary mineral phases and precipitation of secondary mineral phases results in the formation of mineral biosignatures. I also study how nutrient limitation influences organic compounds in snow algae, and therefore, potential organic biosignature formation.
The image here is of snow algae consortia associated with forsterite weathering. They gain iron from the olivine to support their growth.
Biovermiculation Patterns in icy planetary environments
Factors that influence habitability of icy planetary environments
Snow algae preferentially grow on Fe-phases and produce secondary Fe-phases