Md Nazmul Hasan

+ CFs] treatment could be a potential alternative for reducing the excess use of CF.

Algae can efficiently harvest phosphorus (P) and store this nutrient as intracellular polyphosphates (polyPs), an ability of industrial potential, such as P-removal during wastewater treatment. However, a better understanding of P metabolism is first needed before P-removal and recovery can be reliably engineered by triggering polyPs synthesis. The proteomic response of Chlamydomonas reinhardtii was therefore studied, for the first time, during growth under different condition of P availability. For this purpose, five biological replicates (controls) were grown on low P media for 18 days while five biological replicates (treatments) were grown under similar conditions until day 11, when they then received 10 mg-P·L−1. In the P-repleted treatments, the rapid increase in cellular P content (%P up to 2.14 g-P·g-DW−1) and granular polyP abundance evidenced an overplus response. Comparative analysis of the proteomes of P-repleted and P-depleted cultures evidenced P-depletion was associated with an increase in the abundance of proteins involved in P assimilation and storage, including polyP synthesis. Hence these cells were ready to rapidly uptake P and intracellularly accumulate polyP upon P-repletion, as verified experimentally. In contrast, P-repletion was associated with an increase in the abundance of proteins involved in ribosome structure and synthesis, and translation, but a decrease in the abundance of proteins associated with P assimilation and storage. Our findings corroborate, for the first time, data from past transcriptomics studies of P-related genes and therefore suggests that the transcriptomic and proteomic responses of P-related genes and proteins are synchronized in C. reinhardtii. These findings unify observations from independent past studies on C. reinhardtii and other microalgae species, suggesting a common evolution of P metabolism (including polyP synthesis) in microalgae. Importantly, the data also suggests that post-translational regulation of the vacuolar transport chaperone subunits control polyP synthesis in C. reinhardtii (rather than transcriptional regulation).