Developing an Evolutionary Roadmap to High Lipid Accumulating Diatoms: A Systematic Appraisal of Amphora Sensu Lato

Stepanek, Joshua G.

Graduate Thesis Or Dissertation

Developing an Evolutionary Roadmap to High Lipid Accumulating Diatoms: A Systematic Appraisal of Amphora Sensu Lato Public Deposited

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Citeable URL: https://scholar.colorado.edu/concern/graduate_thesis_or_dissertations/xs55mc089

Abstract

Products derived from microalgal lipids have long been touted as an efficient and renewable alternative to the plant, animal and petroleum based products currently available. The great promise provided by algae as a biomass feedstock stems from their ubiquitous distribution, metabolic diversity, high productivity and ability to be grown on non-agricultural lands utilizing brackish and saltwater sources. Although promising, commercial production of algal products has not reached levels predicted by early investigators. Despite 40 years of algal biomass research, our basic understanding of the diversity and evolutionary history of these organisms remains in its infancy. If the great potential of algal derived products are to be realized, a biologically relevant approach to strain selection must be adopted. Presented here is a systematic investigation into the taxonomic, evolutionary and lipid accumulation diversity within the oleaginous diatom genus Amphora sensu lato. This is approached by first examining the taxonomic diversity of Amphora present within coastal and inland waters. From environmental collections made at these sites, a molecular phylogeny is produced to serve as the backbone for lipid accumulation experiments and comparisons. Based on the taxonomic and phylogenetic results, the Halamphora group within Amphora sensu lato was selected for a phylogenetically based appraisal of lipid production across cultured strains. This appraisal has demonstrated that ecological preference and cellular lipid accumulation within Halamphora exhibits a significant phylogenetic signal and therefore evolutionary relationships can be used as predictors of trait expression. The ecological and lipid data taken together with the taxonomic and phylogenetic data make for a predictive evolutionary based tool for the selection of high lipid accumulating lineages within Halamphora as well as laying the groundwork for future comparative research.

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