Ms. Hsu Yee Htet

Microalgal biotechnology offers opportunities for the growing market and sustainable production of health-beneficial molecules and key food ingredients. Long-chain polyunsaturated fatty acids (LC-PUFA) derived from microalgae are currently used as food and feed additives, offering numerous health benefits. LC-PUFA are key components of neuronal membranes and have an impact on cardiovascular health and inflammation. Some microalgae have high levels of omega-3 LC-PUFA, such as eicosapentaenoic acid (EPA), while accumulation of omega-6 LC-PUFA is uncommon. Oxidative stress conditions often occur during microalgae cultivation, which can impair productivity and deteriorate LC-PUFA content. In this study, we investigate the mechanisms of enhanced oxidative stress tolerance of the mutant strains of two LC-PUFA producing microalgae, Nannochloropsis oceanica and Lobosphaera incisa. Nannochloropsis oceanica accumulates eicosapentaenoic acid (EPA, 20:5 n-3) in polar lipids and Lobosphaera incisa sequesters exceptional amounts of arachidonic acid (ARA, 20:4 n-6) in the storage lipid triacylglycerol (TAG). The mutant strains of N. oceanica were isolated based on their resilience to the photosensitizer Rose Bengal, which is thought to promote singlet oxygen formation. The transgenic strains of L. incisa overexpress the hallmark protein of autophagy, ATG8. We perform a detailed screening of L. incisa strains responses to stress conditions to elucidate the role of autophagy enhancement in stress tolerance, fatty acid, and lipid production. The strains are cultivated under a range of specific conditions for the determination of growth and photosynthetic parameter and fatty acid abundance. The analysis of the proteome of N. oceanica RB mutants grown under high light is underway to identify potential protein candidates associated with increased resilience to high light.