초록
<P><B>Highlights</B></P><P>► The lipid accumulation under N-repletion conditions. ► The carbohydrate accumulation under N-depletion conditions. ► <I>I. zhangjiangensis</I> is an ideal candidate for producing biodiesel using N-rich wastewater.</P> <P><B>Abstract</B></P><P>Effects of nitrate feeding on the cell growth and lipid accumulation of marine microalgae <I>Isochrysis zhangjiangensis</I> were investigated. When nitrate was supplied at interval of 24h, instead of 72h, a high lipid content of 40.9% and a biomass density of 3.1gL<SUP>−1</SUP> were obtained. To confirm whether <I>I</I>. <I>zhangjiangensis</I> accumulates lipid during nitrogen-repletion, a two-stage cultivation method was applied. This algal strain had a high lipid content during sustained nitrate addition and showed a high carbohydrate content under nitrate-depletion conditions. These results revealed that this algal strain can accumulate lipids under nitrogen-repletion conditions and accumulate carbohydrate under nitrogen-depletion conditions. When cultured in an extremely high nitrate concentration, 9gL<SUP>−1</SUP> at 24h intervals, the growth of algal cells was suppressed, but the highest lipid content of 53% was attained. This special characteristic of lipid accumulation makes <I>I</I>. <I>zhangjiangensis</I> an ideal candidate for producing biodiesel using N-rich wastewater.</P>