Phosphorus deficiency and high light treatment affect the photophysiology and lipid accumulation of Palmellococcus miniatus

Palmellococcus miniatus, a lipid-rich green microalgae, was selected as an experimental material. We exposed P. miniatus cultures to low (100 μmol·m^-2·s^-1) and high (600 μmol·m^-2·s^-1) light, and investigated the effect of phosphorus deficiency on the photophysiology and lipid accumulation in P. miniatus. Results showed that phosphorus deficiency decreased the photosystem Ⅱ maximum photochemical yield (F_v/F_m), inhibited the electron transfer from Q_A^- to Q_B, and lowered the protein content, thus resulting in a reduction in growth and biomass. However, phosphorus deficiency induced a significant accumulation of lipids. When supplemented with high light, the photosynthesis of P. miniatus was further suppressed and protein content was markedly decreased, whereas lipid content increased significantly. Our results show that the combined treatments of phosphorus deficiency and high light stimulated lipid accumulation in P. miniatus.