Doctoral Dissertations

Date of Award


Degree Type


Degree Name

Doctor of Philosophy



Major Professor

Jill Mikucki

Committee Members

Steven Wilhelm, Alison Buchan, Tim Sparer, Mona Papes


Microbiology of cryosphere systems are understudied and at risk as Earth’s climate continues to change. These systems are often at extreme boundaries to what microbial life can withstand and as such require adaptations that enable life to survive and thrive in some of Earth’s harshest conditions. The microorganisms in these environments may play a large yet not fully understood role in the global carbon budget. In order to understand the microbiology of these systems, their bioprospecting potential, and their role in global biogeochemical cycles, it is imperative to gain access to and study these parts of the cryosphere before they are lost to global climate change.

This dissertation investigates the cryosphere from three different environments utilizing a variety of microbiological techniques, including multi-omics bioinformatic approaches, cultured based approaches, field-based measurements, and instrument development. Access to ice-covered environments remains a physical and logistical challenge, Chapter 1 of this dissertation explores mechanisms of possible contamination when melting through ice with a novel probe used for sample acquisition. The work provides the first controlled melt probe experiments to investigate particle and microbial cell movement as it relates to contamination and melt probe descent for subglacial lakes and astrobiological targets. Chapter 2 explores the life cycle of snow algae from the Pacific Northwest and the potential role that the life cycle has on snow microbial ecology and the carbon budget of snowpack. The final chapter investigates adaptations of the phototrophic inhabitants of a microbial mat near Don Juan Pond, one of the most hypersaline liquid features on Earth, which are exposed low temperatures, elevated calcium chloride conditions, as well as both low and high light irradiances. The phototrophic genetic potential of the mat is compared to other polyextreme environments. Collectively this dissertation investigates the genetic potential, community composition, and activity in remote cryosphere locations that are in danger of being lost to climate change.

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