Investigations into the concomitant production of triacylglycerides and carotenoids by Rhodotorula diobovata

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dc.contributor.authorFakankun, Irene
dc.contributor.examiningcommitteeCicek, Nazim (Biosystems Engineering) Court, Deborah (Microbiology) Fristensky, Brian (Plant Science)en_US
dc.contributor.supervisorLevin, David (Biosystems Engineering)en_US
dc.date.accessioned2021-07-28T14:24:51Z
dc.date.available2021-07-28T14:24:51Z
dc.date.copyright2021-06-11
dc.date.issued2021-06en_US
dc.date.submitted2021-06-11T18:50:23Zen_US
dc.degree.disciplineBiosystems Engineeringen_US
dc.degree.levelDoctor of Philosophy (Ph.D.)en_US
dc.description.abstractOleaginous red yeasts are capable of producing an array of useful bioproducts including triacylglycerides (TAGs) for biodiesel and carotenoids for nutraceuticals. The previously under-characterized oleaginous red yeast, Rhodotorula diobovata, was the focus of this research. This study first examines the effect of aeration on R. diobovata grown under nitrogen-limiting conditions. Results showed a link between nitrogen-limitation and the onset of TAG synthesis, and a link between oxygen-limitation and the onset of carotenoid synthesis. To understand the molecular basis of these results, and R. diobovata’s productivity under varying culture conditions, the genome was sequenced, assembled, annotated and compared with other oleaginous yeasts in relation to their TAG and carotenoid biosynthesis. Amino acid sequence alignments of key proteins in the de novo fatty acid and carotenoid biosynthesis pathways revealed core differences between R. diobovata and other oleaginous non-carotenogenic yeasts such as Yarrowia lipolytica and Lipomyces starkeyi. A dot-plot analysis of the nucleotide sequences of key genes in the de novo fatty acid and carotenoid biosynthesis pathways revealed multiple inversions and frame shifts between the phenotypically similar R. graminis WP1 and R. diobovata. The availability of the annotated genome allowed for a robust proteomic investigation of R. diobovata conditions across growth phases under nitrogen- and oxygen- limiting conditions. Nitrogen- and oxygen-limitation across growth phases resulted in elevated levels of NADPH supplying proteins and downregulation of acetyl-CoA supplying proteins, which resulted in an overall reduction of fatty acid synthesis. The carotenoid biosynthetic pathways were however upregulated resulting in increased concentrations of carotenoids. This implies that the flux of acetyl-CoA favoured isoprenoid biosynthesis over fatty acid biosynthesis under nitrogen- and oxygen- limiting conditions across growth curve. Overall, this work presents the first publicly available whole genome sequence and annotation of R. diobovata. It provides valuable data on comparative genomics and proteomics analyses, which can be utilized in the engineering of Rhodotorula diobovata to maximize their TAG and carotenoid productivity.en_US
dc.description.noteOctober 2021en_US
dc.identifier.citationFakankun, I., Fristensky, B., & Levin, D. B. (2021). Genome sequence analysis of the oleaginous yeast, Rhodotorula diobovata, and comparison of the carotenogenic and oleaginous pathway genes and gene products with other oleaginous yeasts. Journal of Fungi, 7(4), 320en_US
dc.identifier.citationFakankun, I., Spicer, V., & Levin, D. B. (2021). Proteomic analyses of the oleaginous and carotenogenic yeast Rhodotorula diobovata across growth phases under nitrogen-and oxygen-limited conditions. Journal of Biotechnology, 332, 11-19en_US
dc.identifier.citationFakankun, I., Mirzaei, M., and Levin, D. B. (2019). Impact of culture conditions on neutral lipid production by oleaginous yeast. In Microbial Lipid Production (pp. 311-325). Humana, New York, NY. vol. 1995 pp. 311-325. . https://doi.org/10.1007/978-14939-9484-7_18.en_US
dc.identifier.urihttp://hdl.handle.net/1993/35757
dc.rightsopen accessen_US
dc.subjectTriacylglyceridesen_US
dc.subjectCarotenoidsen_US
dc.subjectProteomicsen_US
dc.subjectGenomicsen_US
dc.subjectOleaginous yeasten_US
dc.titleInvestigations into the concomitant production of triacylglycerides and carotenoids by Rhodotorula diobovataen_US
dc.typedoctoral thesisen_US
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