Plant growth regulator triggered metabolomic profile leading to increased lipid accumulation in an edible marine microalga

Abstract

Omega-3 fatty acids containing microalgae are considered a promising feedstock for food and nutraceutical applications. To meet the commercial and nutritional demands of essential omega-3 fatty acids, different strategies are being implemented, including supplementation of plant growth regulators (PGRs). In the present study the effects of selected, PGRs, i.e., gibberellic acid (GA), and salicylic acid (SA), and malic acid (MA; TCA cycle intermediate), were studied on growth, lipid, and omega-3 fatty acid synthesis of Nannochloropsis oceanica CASA CC201. Significant increase in growth (10 ppm GA), a 1.9-fold increase in lipid production (40 ppm MA), and a 4-fold increase in EPA production by treatment with 10 ppm MA were found. To understand the mechanism behind significant changes in growth and metabolite production, we had analyzed the generation of oxidative stress, targeted metabolite, and amino acid profile of N. oceanica under PGR treatment. To elucidate the physiological role of key metabolic pathways and contribution to lipid synthesis, the targeted metabolites were selected from glycolysis, citric acid cycle, and pentose phosphate pathway. Metabolomics analysis revealed that there is a significant increase in ATP, NADPH, NADP, and NADH at cultures treated with high concentrations of selected PGRs and significant elevation of these metabolites are associated with increased lipid production.