Improving biomass of the marine microalga Nannochloropsis oculata by chemical elicitation

Marine microalgae are of particular interest due to their ability to biosynthesise specialised metabolites with a variety of important properties, such as antioxidant and antimicrobial potential. Neutral lipids produced by microalgae are also of huge importance because of their desirable characteristics for the development of new generation biofuels. Stress culture conditions, such as nitrogen starvation, are favourable for inducing the biosynthesis of certain metabolites (e.g., lipids), but supplementation with phytohormones is another viable method for promoting specialised metabolite accumulation. The eustigmatophyte Nannochloropsis oculata, an industrially used species, was cultured autotrophically in the presence of methyl jasmonate (MJ) and salicylic acid (SA) to determine the effects on growth and lipid biosynthesis. Interestingly, 100 μM of MJ added on day 21 of cultivation elicited a 34.3% higher accumulation of lipids than nitrogen starved conditions (0 mg/L NaNO3). Treatment with SA at 250 μM on day 21 promoted a high lipid accumulation in N. oculata (58.5%, p < 0.05) while having the least detrimental impact on cell growth (in comparison with MJ, p > 0.05). Phylogenetic analysis revealed that the distribution of lipid biosynthesis genes (LPAAT and DGAT) in Nannochloropsis were linked to the evolutionary relatedness (18s rRNA) of the strains. Phytohormones are effective at promoting high lipid accumulation in N. oculata, but it would be beneficial to implement a wider range of concentrations to further understand the impacts of high and low concentrations on growth. A transcriptomics approach would be valuable for providing a deeper understanding into the metabolic pathways that are influenced by phytohormone treatments. Phytohormone supplementation could be beneficial to the industry as it has shown to have minimal negative impacts on biomass while simultaneously promoting a high accumulation of intracellular lipids in comparison to traditional methods (nitrogen starvation).

Name dc:type.qualificationname

mres

Level dc:type.qualificationlevel

masters-pg

Grantor dc:publisher.institution

University of Strathclyde

Year dc:date.issued

2022

Author dc:creator

• McFadden, Constance Johanne

Advisor dc:contributor.advisor

• Duncan, Katherine R.

DOI

10.48730/psn2-p127

Identifier

T16320

Author Identifier

202073527

OAI identifier oai:identifier

oai:strathclyde:3b591908s