Regulation Of Envionmental Factors In The Process Of Lipid Accumulation Of A Marine Diatom

The studies of microalgae bioenergy are mainly focused on green algaes and diatoms, which are mainly freshwater microalgaes, while the studies of marine microalgaes for bio--energy are less, especially for red tide microalgaes. Using marine red tide microalgaes to produce bioenergy can not only save a lot of freshwater, we can also gain a lot of algae bi--omass in a short time once the rapid proliferation mechanism of red tide microalgaes be revealed and used by human, so we can reduce the cost of microalgae bioenergy. The gro--wth and biochemical composition of microalgaes are closely related to culture conditions, the growth and lipid accumulation of microalgae can be significantly effect by medium co--mposition and changes of temperature, light, salinity, and other ventilation conditions. In this article, effects of three nitrogens, silicon and iron on growth, photosynthetic activity a--nd lipid accumulation of a common red tide algae Skeletonema were studied.The results showed that the most suitable nitrogen for the growth of Skeletonema was ammonium, then urea and nitrate was the last. The optimum level of three nitrogen sources for Skeletonema growth all were4.4×10-4mol/L. The variation of photosynthetic activity of Skeletonema were consistent with that of growth rate.The most suitable nitrogen for lipid accumulation of Skeletonema was ammonium, and the level concentration was8.8×10-6mol/L, while the highest lipid content was31.07%.The most suitable silicon level for the growth of Skeletonema was1.7×10-4mol/L. L--ow silicon levels could promote the lipid accumulation in single cells of Skeletonema, but the promotion of total lipid content was not obvious. High silicon levels could significantly promote lipid accumulation of single cells and total lipid content, the most suitable silicon concentration for lipid accumulation of Skeletonema was4.3×10-4mol/L, while the highest lipid content was21.61%.The most suitable iron level for the growth of Skeletonema was6.0×10-5. High levels of iron didn’t promote the lipid accumulation of Skeletonema.Compared the optimized f/2medium consisted of the most suitable levels of ammon--ium, silicon and iron for lipid accumulation of Skeletonema with the standard f/2medium, the growth difference between the two mediums was little, but lipid accumulation of Skele--tonema in the optimized f/2medium was significantly higher than it in standard f/2medi--um. The lipid content of Skeletonema in the two mediums were43.75%and9.78%.