Nannochloropsis gaditana is well known for its potential for biofuel production due to its high lipid content. Numerous omics and biochemical studies have explored the overall molecular mechanisms underlying the responses of Nannochloropsis sp. to nutrient availability, primarily focusing on lipid metabolism. However, N. gaditana is able to synthesize other valuable products such as carotenoids, including violaxanthin, which has various biological functions and applications. In this study, we comparatively investigated the physiological, biochemical, and molecular responses of N. gaditana to nitrogen and phosphorus limitation, examining biomass production, photosynthetic activity, lipid, chlorophyll, and carotenoids content, and RNA-seq data. Nitrogen limitation decreased photosynthetic activity, chlorophyll content, and biomass production but increased lipid content. Phosphorus limitation substantially increased carotenoids content, with violaxanthin productivity of 10.24 mg/L, 3.38-fold greater than under the control condition, with little effect on biomass production or photosynthetic function. These results were generally consistent with the gene expression pattern observed in transcriptomic analysis. This integrated analysis shows that phosphorus limitation can be an economically competitive solution by enhancing valuable carotenoids while maintaining lipid and biomass production in N. gaditana.

Microalgae have garnered increasing attention as promising sources of diverse natural anti-inflammatory compounds, including carotenoids, phenolics, and unsaturated fatty acids. In this study, we aimed to examine the anti-inflammatory properties of the methanol extract of Nannochloropsis sp. G1-5 (NG15), a strain of marine microalgae isolated from the southern West Sea of the Republic of Korea. Pigment and metabolite analyses revealed that the extract contained various carotenoids and polyunsaturated fatty acids alongside significant quantities of phenolic and flavonoid compounds, which are known to have anti-inflammatory activities. Cytotoxicity assays confirmed that the extract was non-toxic to RAW 264.7 macrophage cells at concentrations up to 1 mg/mL. Upon lipopolysaccharide (LPS) stimulation of the macrophage cells, the NG15 extract significantly inhibited nitric oxide (NO) production in a dose-dependent manner up to 81%. In addition, the NG15 extract reduced the expression of iNOS, COX-2, TNF-α, and IL-6 in the LPS-stimulated cells. These findings suggest that NG15 methanol extract exerts anti-inflammatory effects primarily through the suppression of NO generation without inducing cytotoxicity. Overall, these results underscore NG15 as a promising natural resource for the development of non-toxic and effective anti-inflammatory agents with potential applications in the biomedical and cosmeceutical industries.