Master of Science Greta Daae Sandsdalen will Friday August 21st, 2026, at 12:15 hold her Thesis Defense for the PhD degree in Science. The title of the thesis is:
« CRISPR in the Cold: Discovery and Development of Cold-Active Genome Editing Systems »
CRISPR-Cas technology provides a versatile platform for genome editing and engineering, yet most enzyme effectors are derived from and optimized for mesophilic organisms. This limits their utility in applications where low temperatures are unavoidable or advantageous. To address this gap, we look to nature’s solutions to cold catalysis. Microbes from polar and other cold environments maintain enzyme function at low temperatures, positioning cold-adapted bacteria as reservoirs of cold-active CRISPR systems. This thesis set out to explore the diversity of CRISPR-Cas systems in cold-adapted bacteria and to develop genome editing tools optimized for low temperatures.
In Paper I, a bioinformatics analysis of 938 high-quality genomes from cold-adapted bacteria revealed an antiphage defense landscape dominated by restriction-modification systems, with complete CRISPR-Cas systems present in only 17.7% of genomes. Several cold-adapted CRISPR-Cas enzymes, such as Cas9 and Cas12a, were identified for further study. Paper II experimentally characterized a novel CRISPR-Cas12a enzyme from a cold-adapted bacteria, which demonstrated robust activity across a broad temperature range (1–50°C) and outperformed an engineered mesophilic variant at 4°C. Paper III investigated the structural and functional adaptations of cold-adapted Cas9 enzymes, revealing localized flexibility and electrostatic tuning that may facilitate DNA engagement at low temperatures.
Collectively, this thesis provides (i) the first comprehensive map of antiphage defense systems in cold-adapted bacteria, (ii) a validated cold-tolerant Cas12a enzyme, (iii) insights into the molecular adaptations of cold-adapted Cas9 enzymes, and (iv) practical strategies for Cas enzyme recombinant production. These findings expand the CRISPR toolbox and show potential for enhancing the genome editing performance in cold-adapted organisms and other low-temperature workflows.
1st Opponent: Assistant Professor Rafael Pinilla-Redondo, Section of Microbiology, University of Copenhagen, Denmark
2nd Opponent: Professor Morten Sørlie, Faculty of Chemistry, Biotechnology, and Food Science, Norwegian University of Life Sciences, NMBU, Ås, Norway
Internal member and leader of the committee: Professor Richard Engh, Department of Chemistry, UiT, Norway
The defence and trial lecture will be streamed from these following links at Panopto:
Defence (12:15 - 16:00)
Trial Lecture (10:15 - 11:15)
The abstract of the thesis is available at Munin Here.