Nitzschia sp and Nanofrustulum shiloi (Diatoms, Bacillariophyta) are the group of photosynthetic eukaryotic microorganisms with the cell walls out of silica called frustules. It is believed that about eight thousands diatom species are described living in freshwater and marine habitats, especially marine diatoms are responsible for the primary production of phytoplankton. (DOI 10.1007/s13765-012-2108-3), doi: 10.1093/jxb/erv340.
Major (nitrogen, phosphorus, and silicon) and trace metal nutrients (cobalt, manganese, iron, copper and zinc) are regulated by productivity in the metabolism of diatoms. Nitrogen is used primarily by microalgae to synthesize proteins and nucleic acids. However, the trace metal effects are mostly less significant than those for iron. Iron stimulates as a cofactor for redox enzymes and for silicic acid transport molecules. Additionally, iron plays a major role in photosynthesis and leads to increasing growth ( ). But the nitrogen and iron deprivation, diatoms reprogram several metabolic pathways. The nitrogen and iron depletion have studied the effect on lipid accumulation, pigments, photosynthesis, carbon fixation in diatoms. doi: 10.1093/jxb/erv340. (https://doi.org/10.1016/j.foodchem.2011.08.062). DOI 10.1007/s13765-012-2108-3) (http://dx.doi.org/10.1016/j.anres.2017.02.004) https://doi.org/10.1016/j.biortech.2010.02.016
Diatoms and edible brown algae are major carotenoid pigments (orange colored) of fucoxanthin that plays a role in the light-harvesting pigments such as chlorophyll a, chlorophyll c, and fucoxanthin of photosystems (doi: 10.3390/md9101806). Fucoxanthin has exhibited many bioactivities, including antioxidant, anti-inflammatory, anticancer, antiobesity (type 2 diabetes with obesity), antidiabetic, antiangiogenic and antimalarial activities, and its protective effects on the liver, cardio-cerebrovascular, bones, skin, and eyes (doi: 10.3390/md9101806) (Mar Drugs. 2011;9(10):1806-28.), Cell Physiol Biochem 2015;37:2464-2475). Diatoms have proven to be important for industrial and commercial products such as biofuels, pharmaceuticals, live foods, biomolecules, materials relevant to nanotechnology, and bioremediations (doi: 10.3390/md13095847) (Spolaore et al., 2006). (DOI 10.1007/s13765-012-2108-3)
In the present study is focused on the effect of the nutrient stress (free and rich nitrogen and iron concentration) on the production of fucoxanthin, total lipid and fatty acid composition in two marine diatoms. The aim of the process is to increase the potential of marine diatoms as a source of high-value compounds for aquaculture feeds or other applications.