Master of Science Mikkel Christensen will Thursday January 29th, 2026, at 12:15 hold his Thesis Defense for the PhD degree in Science. The title of the thesis is:
« Characterization of Arctic marine γ-proteobacteria for sustainable production of polyhydroxyalkanoates (PHA) »
Polyhydroxyalkanoates (PHA) are polyesters produced by bacteria with potential use as biodegradable bioplastics. In this work, γ-proteobacteria isolated from the Arctic littoral environment by our group (Cobetia sp. MC34 and Halomonas sp. MC140), retrieved from UiT’s culture collections (Halomonas sp. R5-57 and Pseudomonas sp. MR4-99), and a marine (non-Arctic) genus type-strain (Cobetia marina DSM 4741T) were initially screened and subsequently characterized for PHA biosynthesis. Characterization included carbon source utilization phenotype, genetic and phylogenetic analyses, and chemical analyses of the PHA polymers. Production of short chain length-PHA (scl-PHA) was confirmed for Halomonas and Cobetia, while mcl-PHA was confirmed for Pseudomonas, consistent with previous studies of PHA production in these genera. Genetic analyses identified a genus-specific polyhydroxyalkanoate synthase variant (PhaC2) in Cobetia, which is hypothesized to be involved in DNA-binding.
The carbon source characterization results are furthermore discussed in the context of sustainable routes for microbiological production of PHA, and these phenotypes lay the foundation for further optimization of PHA production, such as the use of second-generation waste substrates, and outlines the potential of using Arctic marine bacteria as a resource for production of PHA biodegradable bioplastics.
A method for use of Fourier-transform infrared spectroscopy (FTIR) combined with small-scale cultivation was demonstrated, and FTIR analyses furthermore enabled differentiation between different types of PHA produced. Demonstration of FTIR for the purpose of predictive modeling of PHA content in bacteria was also accomplished. These methodological advancements highlight the potential of FTIR as a rapid and efficient tool for PHA screening and production optimization.
1st Opponent: Professor Izabela Radecka, Faculty of Science and Engineering, University of Wolverhampton, UK
2nd Opponent: Professor Helga Ertesvåg, Department of Biotechnology and Food Science, NTNU
Internal member and leader of the committee: Researcher Dr. Espen Åbert, IK, NT Faculty, UiT