Evaluation of changes in M. aeruginosa growth and microcystin production under phosphorus starvation via...

Phosphorus (P) is an important nutrient for the growth and metabolism of algae. Although P typically limits the growth of algae, little is known regarding the molecular response of Microcystis aeruginosa under P starvation. The transcriptomic and physiological responses of Microcystis aeruginosa to P starvation were investigated in this study. P starvation affected the growth, photosynthesis, and Microcystin (MC) production of Microcystis aeruginosa and triggered cellular P-stress responses for 7 days. In terms of physiology, P starvation inhibited the growth and MC production, while the slight promotion of photosynthesis in Microcystis aeruginosa compared to P-replete. For transcriptome, the down-regulation of genes related to MC production controlled by mcy genes and ribosome metabolism (17 genes encoding ribosomal proteins) was observed while transport genes (sphX and pstSAC) were significantly upregulated. In addition, some other genes are related to photosynthesis and the use of other forms of P displayed increases or decreases in transcripts abundance. These results suggested that the limitation of P had a diverse performance on aspects of growth and metabolism in M. aeruginosa and obviously enhanced the ability to adapt to the P stress environment. They provide a comprehensive understanding of the P physiology of Microcystis aeruginosa and theoretical support for eutrophication.