A two-stage model with nitrogen and silicon limitation enhances lipid productivity and biodiesel features of the marine bloom-forming diatom Skeletonema costatum

•N-Si-limitation increased lipid productivity by 76.7% for 6 h induction.•N-Si-limitation increased lipid productivity by 113.7% for 12 h induction.•N-Si-limitation enhanced the proportions of SFA and MUFA but reduced PUFA.•N-Si-limitation reduced iodine value by 33.7% for 6 h and 45.6% for 24 h induction.•N-Si-limitation increased cetane number by 6.4% for 6 h and 21.6% for 24 h induction. To enhance biodiesel production and quality from a bloom-forming diatom Skeletonema costatum, a two-stage model, in which cells were cultured in nutrient replete conditions first and then transferred to nutrient limitation conditions, was explored. Compared to one-stage model, nutrient limitation in the second stage significantly increased lipid content in spite of decreasing growth; consequently, Si-limitation and N-Si-limitation respectively increased lipid productivity by 37.6% and 76.7% for 6 h induction, and 42.8% and 113.7% for 12 induction. Nutrient limitation enhanced the proportions of saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA) but reduced polyunsaturated fatty acid (PUFA). Therefore, N-Si-limitation reduced iodine value by 33.7% and 45.6% but increased cetane number by 6.4% and 21.6% for 6 and 24 h induction, respectively. These findings indicate that the two-stage model with N-Si-limitation can enhance lipid productivity as well as biodiesel quality from diatoms.