Reconstruction and analysis of a genome-scale metabolic model of Nannochloropsis gaditana

Nannochloropsis gaditana is a promising marine microalga for biotechnological applications due to its capacity to accumulate large amounts of lipids and to synthesize valuable chemicals for the food industry. To identify the metabolic capabilities of this organism, a broad-level understanding of its metabolism is needed, which can be accomplished by a large-scale metabolic model. In this work, we present the first functional compartmentalized genome-scale metabolic model of this microalga, which we call iRJ1321. It includes 1321 genes, 1918 reactions, and 1862 metabolites and is thus the largest algal genome scale metabolic model to date in terms of number of genes and percentage gene coverage. The model-predicted growth rate matches reasonably well with the literature reported growth rate for photoautotrophic growth. The model was applied to capture the role of nitrogen limitation in remodeling N. gaditana metabolism. The flux distribution in iRJ1321 predicts C4-like carbon-concentrating co-existing with Calvin cycle. This model will be useful to researchers interested in understanding capabilities and limitations of N. gaditana metabolism and devising metabolic engineering strategies for synthetic pathway design for production of diverse molecules.