Chlorella is a unicellular microalga containing abundant nutritious substances such as carotenoids and antioxidants,and it is marketed as health food,speciality feed and source of pigments.As one of the major elements in the cell,phosphorus is an essential ingredient in microalgal culture media.Basal medium has been widely applied in the cultivation of microalgae since the 1950s.The overuse of phosphates is not only a waste of resources but also a possible factor leading to the eutrophication.Therefore,determination of phosphorus assimilation by Chlorella and adjustment of phosphate concentration in Basal medium are essential.