Phosphorus plays an important role in enhancing biodiesel productivity of Chlorella vulgaris under nitrogen deficiency

► P is important to enhance algal lipid productivity under nitrogen deficiency (N−). ► Lipid productivity under N− with sufficient P supply is highest as 58.39 mg/L/day. ► P uptake rate under N− is 3.8 times faster than that of sufficient N&P supply. ► 31P NMR shows that uptake P is accumulated as polyphosphate in algal cells.