Significant influence of phosphorus resources on the growth and alkaline phosphatase activities of Microcystis aeruginosa.

It is well-accepted that phosphorus, particularly orthophosphate, is a determinant factor in aquatic eutrophication. However, numerous kinds of phosphorus sources exist in real world scenario, and limited studies have characterized the pairwise relationships among abundant different phosphorus sources and the physiological behaviour of algae. The present study developed a high-throughput assay to investigate the effects of 59 different phosphorus sources (equal initial concentration of total phosphorus) on the growth and alkaline phosphatase (AKP) activities of Microcystis aeruginosa, a model cyanobacteria whose predominance holds sway in lake eutrophication. M. aeruginosa cultivated with nucleoside monophosphates (NMPs) had higher growth, relative AKP activities and residual orthophosphate, which were positively intercorrelated. Oppositely, non-NMPs cultivation of M. aeruginosa led to negative relationships between the relative AKP activities and their growth or residual orthophosphate. These results indicated distinct mechanisms for M. aeruginosa to utilize different phosphorus sources in real-world scenario, and both phosphorus source and content are determinant factors on the growth and physiological behaviour of M. aeruginosa. Given the complicated and vast phosphorus pool in the natural environment, phosphorus resources might significantly alter the abundance and physiological behaviour of M. aeruginosa and other bloom-forming algae, then influence the phytoplanktonic community structure and affect the possibility and intensity of algal bloom. Our work hints the underestimation of the restriction factors in lake eutrophication and provides a new tool to study the driven forces of phytoplanktonic community dynamics as phosphorus from both internal and external sources.